COTTON ENTOMOLOGY RESEARCH REPORT 2015

Transcription

1 TEXAS A&M AGRILIFE RESEARCH & EXTENSION CENTER AT LUBBOCK COTTON ENTOMOLOGY RESEARCH REPORT 2015 TECHNICAL REPORT 16-4 TEXAS A&M AGRILIFE RESEARCH, CRAIG NESSLER, DIRECTOR THE TEXAS A&M SYSTEM, COLLEGE STATION, TEXAS

2 COTTON ENTOMOLOGY PROGRAM RESEARCH ACTIVITY ANNUAL REPORT 2015 SUBMITTED TO: PLAINS COTTON IMPROVEMENT COMMITTEE PLAINS COTTON GROWERS, INC. JAROY MOORE, RESIDENT DIRECTOR TEXAS A&M AGRILIFE RESEARCH-LUBBOCK BY: Dr. Megh N. Prjulee Professor, Fculty Fellow, nd Texs A&M Regents Fellow Texs A&M AgriLife Reserch Cotton Entomology Progrm Luock, Texs Phone: (806) Fx: (806) Emil:

3 PARTICIPANTS MEGHA N. PARAJULEE, Texs A&M AgriLife Reserch-Luock ABDUL HAKEEM, Texs A&M AgriLife Reserch-Luock CHANDRA K. DHAKAL, Texs Tech University SEAN COYLE, Texs A&M AgriLife Reserch-Luock STANLEY C. CARROLL, Texs A&M AgriLife Reserch-Luock EDUARDO SEGARRA, Texs Tech University KELLY LANGE, Texs Tech University KATE HARRELL, Texs A&M University, College Sttion GREGORY SWORD, Texs A&M University, College Sttion GAYLON MORGAN, Texs A&M AgriLife Extension, College Sttion SARANYA GANAPATHY, Texs Tech University HONG ZHANG, Texs Tech University MICHAEL SAN FANCISCO, Texs Tech University RICHARD NORMAN, Texs A&M AgriLife Reserch-Luock MARK D. ARNOLD, Texs A&M AgriLife Reserch-Luock JANE K. DEVER, Texs A&M AgriLife Reserch-Luock JIM BORDOVSKY, Texs A&M AgriLife Reserch-Hlfwy WAYNE KEELING, Texs A&M AgriLife Reserch-Luock DANNY MEASON, Texs A&M AgriLife Reserch-Luock BEAU HENDERSON, Texs A&M AgriLife Reserch-Luock DYLAN WANN, Texs A&M AgriLife Reserch-Luock DANNY CARMICHAEL, Texs A&M AgriLife Reserch-Lmes MICHAEL BREWER, Texs A&M AgriLife Reserch-Corpus Christi FRED MUSSER, Mississippi Stte University, Mississippi Stte FENG GE, Chinese Acdemy of Sciences, Beijing, Chin BLAYNE REED, Texs A&M AgriLife Extension Service-Plinview JIM WILBORN, Texs A&M AgriLife Reserch-Chillicothe CASEY HARDIN, Texs A&M AgriLife Reserch-Hlfwy CALVIN TROSTLE, Texs A&M AgriLife Extension Service-Luock FUNDING AND LOGISTICAL SUPPORT USDA NIFA, Cotton Incorported Core Progrm, CI Stte Support Committee, Texs A&M AgriLife Reserch, Texs A&M AgriLife Extension Service, Plins Cotton Growers, Inc., ADAMA, StollerUSA

4 TABLE OF CONTENTS INTRODUCTION.. 1 SUMMARY HIGHLIGHTS OF SELECTED COTTON ENTOMOLOGY PROGRAM RESEARCH.. 2 EFFECT OF NITROGEN FERTILIZER ON COTTON FLEAHOPPER DAMAGE POTENTIAL AND CROP RESPONSE TO INJURY 3 COTTON YIELD RESPONSE TO COTTON FLEAHOPPER ACUTE INFESTATIONS AS INFLEUNCED BY IRRIGATION TREATMENTS IN LAMESA.. 4 EVALUATION OF COTTON FLEAHOPPER DAMAGE POTENTIAL AND CROP RESPONSE TO INJURY UNDER VARIABLE NITROGEN FERTILITY LEVEL... 7 DEVELOPMENT OF ECONOMIC THRESHOLD AND MANAGEMENT RECOMMENDATIONS FOR LYGUS IN TEXAS HIGH PLAINS COTTON CHARACTERIZATION OF COTTON CROP RESPONSE TO THRIPS INJURY FOR IMPROVED THRIPS MANAGEMENT IN TEXAS HIGH PLAINS COTTON THRIPS MANAGEMENT IN TEXAS HIGH PLAINS COTTON SEASONAL ABUNDANCE PATTERNS OF BOLLWORM, TOBACCO BUDWORM, AND BEET ARMYWORM MOTHS IN THE TEXAS HIGH PLAINS PHEROMONE TRAPPING OF HELICOVERPA MOTH SPECIES IN THE TEXAS HIGH PLAINS: INVESTIGATION OF POSSIBLE OLD WORLD BOLLWORM DETECTION EFFICACY OF NEONICOTINOID SEED TREATMENTS ON THRIPS IN COTTON.. 81 BREEDING VALUE OF HOST PLANT THRIPS RESISTANCE FOR NEW CULTIVAR DEVELOPMENT UTILIZATION OF NO-THRIPS CAGES TO QUANTIFY THRIPS-INDUCED LOSSES TO COTTON IN THE TEXAS HIGH PLAINS USE OF A MODIFIED-VIRAL GENE TO CONFER RESISTANCE AGAINST APHIDS IN TRANSGENIC PLANTS. 93 LATE SEASON LYGUS HESPERUS MANAGEMENT IN TEXAS COTTON. 94 UPDATE ON BOLLWORM PYRETHROID RESISTANCE MONITORING.. 98 MOISTURE CONDITIONS FOR LABORATORY REARING OF COTTON FLEAHOPPERS FROM OVERWINTERED EGGS LAID ON WOOLLY CROTON PLANTS 103 CROP DOMINANCE EXERTS SPECIFIC EFFECTS ON FOLIAGE-DWELLING ARTHROPODS IN BACILLUS THURINGIENSIS COTTON. 111

5 Introduction Plins Cotton Growers, Inc. (PCG) hs een strong supporter of cotton insect reserch nd extension ctivities in west Texs for mny yers. Most notly, PCG ws instrumentl in securing stte funds for the Boll Weevil Reserch Fcility t the Luock Center, nd provided oth finncil nd politicl support to conduct oll weevil iology nd ecology reserch even efore the oll weevil ecme significnt economic pest of the High Plins region. After the initil entry of the oll weevil into the estern edge of the High Plins, PCG promoted nd long with USDA-APHIS dministered the oll weevil dipuse suppression progrm involving tem effort tht continued to include Texs A&M University. PCG lso supported Texs Coopertive Extension (now Texs A&M AgriLife Extension Service) efforts to nnully evlute the dipuse suppression progrm, conduct pplied reserch trils to develop oll weevil mngement prctices tht would enhnce the dipuse suppression progrm s efforts nd in the 1990s supported n nnul survey of High Plins overwintering sites nd grid trpping of cotton cross the High Plins re. Under the strong nd coopertive ledership of PCG, the oll weevil erdiction progrm for the High Plins re progressed much more rpidly thn nticipted. Now, the successful oll weevil erdiction progrm hs eliminted the oll weevil from this region for over decde. In 2015, ll 11 West Texs zones (Southern Rolling Plins, El Pso/Trns Pecos, St. Lwrence, Permin Bsin, Rolling Plins Centrl, Western High Plins, Southern High Plins/Cprock, Northern Rolling Plins, Northern High Plins, Northwest Plins, nd Pnhndle) hve een declred oll weevil erdicted. The tem effort of PCG, Texs A&M AgriLife Reserch nd AgriLife Extension Service over severl decdes hs resulted in comprehensive understnding of oll weevil ecology nd ehvior. With successful oll weevil erdiction progrm nd incresed doption of the Bollgrd technology (now >70%), the cotton insect reserch nd extension progrm focus hs chnged considerly during the lst 15 yers. Our current reserch/extension focus is on developing ecologiclly intensive strtegies for cotton pest mngement, including crop phenology, cultivr, non-crop hitt, irrigtion, nd fertility mngement towrds reducing insect pest pressure. Our reserch hs demonstrted the need for continuing investigtion of sic ehvior nd life ptterns of insects while hving strong field-sed pplied reserch to ridge the gp etween sic, prolem-solving science nd producer-friendly mngement recommendtions. We hve ssemled strong group of people to work s tem to exmine multiple disciplines within the rod theme of Cotton IPM. We invest considerle time nd mnpower resources in investigting the ehvior nd ecology of mjor cotton pests of the High Plins with the gol of developing mngement thresholds sed on cotton production technology. Our Progrm hs successfully leverged reserch funds sed on the funding provided y PCIC to support our Technicin position. We re excited out nd gretly vlue our Cotton Entomology reserch nd extension prtnerships with multidisciplinry scientists t the Texs A&M AgriLife Center, together with re IPM gents in the region, to continue this prtnership s we chllenge ourselves to deliver the est cotton insect-pest mngement recommendtions to our Texs High Plins producers. 1

6 Texs A&M AgriLife Reserch & Extension Center t Luock COTTON ENTOMOLOGY PROGRAM Megh N. Prjulee, Ph.D. Professor, Fculty Fellow, nd Texs A&M Regents Fellow PROGRAM OVERVIEW: The Cotton Entomology Progrm t Luock comines sic nd pplied reserch with strong outrech, industry, nd grower prtnerships to produce informtion to enhnce the ility of the cotton industry in the Texs High Plins to mitigte cotton yield losses due to insect pests through the use of ecologiclly intensive integrted pest mngement. Selected projects of the Progrm re riefly highlighted in this exhiit. COTTON FLEAHOPPER POPULATION DYNAMICS AS AFFECTED BY NITROGEN FERTILITY; HALFWAY, TEXAS A multi-yer study investigting the effects of differentil nitrogen fertility on cotton flehopper popultion dynmics in typicl drip-irrigtion Texs High Plins cotton production system hs een initited from the 2014 growing seson. Differentil nitrogen fertility (0, 50, 100, 150, nd 200 ls N/cre) is eing exmined for its ffect on cotton plnt physiologicl prmeters, therey influencing cotton flehopper injury potentil nd plnt compenstion. Cotton flehopper ugmenttion in multi-plnt cges to quntify the response of vrile rtes of N to FH injury SEASONAL ABUNDANCE PATTERNS OF BOLLWORM, TOBACCO BUDWORM, AND BEET ARMYWORM MOTHS IN THE TEXAS HIGH PLAINS A long-term study hs een conducted in the Texs High Plins to investigte the yer-round weekly moth flight ctivity ptterns of ollworms, tocco udworms, nd eet rmyworms. These three species re importnt cotton pests in the High Plins. The regionl doption of cotton nd corn cultivrs incorporting Bt technology hs een instrumentl in reducing the current thret of these lepidoptern pests, yet diminishing underground wter vilility for irrigtion is necessitting lower crop inputs, such s trnsgenic seed costs, for our incresing drylnd crop production crege, incresing the importnce of these pests. Texs Pheromone (TP) nd Bucket trps used to monitor moths STATEWIDE SURVEY OF BOLLWORM MOTHS FOR POSSIBLE OLD WORLD BOLLWORM DETECTION IN TEXAS The ojective of this study is to conduct sttewide monitoring of Helicoverp rmiger in Texs which will e used to inform growers nd consultnts nd serve s the foundtion for the development of mngement strtegies. Plstic ucket trps nd pheromone lures will e used to collect moths; moths will e dissected to distinguish Old World nd New World ollworm sed on genitl chrcteristics. 2 DEVELOPMENT OF ECONOMIC THRESHOLD AND MANAGEMENT RECOMMENDATIONS FOR LYGUS BUG Texs A&M AgriLife Cotton Entomology Progrm hs een providing unique ledership in Lygus reserch cross the United Sttes cottonelt since We hve quntified the compenstion ility of cotton to Lygus-induced fruit loss nd the recommendtion hs een mde to our producers tht pesticide pplictions prior to 30% preflower nd 25% erly flower fruit shed my not e necessry. We lso hve developed lte-seson insecticide termintion guideline for Texs High Plins cotton growers, ccording to which, insecticide intervention for Lygus control my not e wrrnted when hrvestle olls ccumulte 350 het units or the oll is 3 cm in dimeter fter crop cut-out. Current effort concentrtes on developing economic thresholdsed mngement recommendtions for Lygus in Texs High Plins cotton, therey iming to minimize economic losses to producers. Continuing studies will exmine the effect of Lygus on drought-stressed nd limited irrigtion cotton. Lygus dults nd nymphs cuse dmge to squres, flowers, nd olls THRIPS MANAGEMENT IN TEXAS HIGH PLAINS COTTON: INSECTICIDE PRODUCT EVALUATION Multi-yer studies re eing conducted t three Texs loctions (Hle, Swisher, nd Wilrger counties) to represent cotton fields surrounded y vrile vegettion/crop complexes nd thrips popultion pressure in cotton. The study ojectives re to: 1) evlute the folir insecticide ppliction frequency in mnging thrips in seedling cotton, nd 2) evlute the efficcy, residul performnce, nd economic competitiveness of selected products in thrips mngement. Insecticides, including seed tretment (thimethoxm [Cruiser ] nd imidcloprid [Aeris ]) nd folir (Orthene, Bidrin, nd Vydte ) tretments re evluted for their efficcy nd cost effectiveness in mnging thrips popultions in cotton reltive to n untreted control. Field evlution of thrips insecticide products

7 EFFECT OF NITROGEN FERTILIZER ON COTTON FLEAHOPPER DAMAGE POTENTIAL AND CROP RESPONSE TO INJURY M.N. Prjulee, A. Hkeem, C.K. Dhkl, S.D. Coyle, S.C. Crroll, J.P. Bordovsky Ojective: The ojective ws to evlute the effect of nitrogen fertilizer ppliction rtes on cotton flehopper dmge potentil nd cotton s response to flehopper injury. Methodology: A high-yielding FierMx cultivr, FM 9180B2F, ws plnted t trgeted rte of 54,000 seeds/cre on My 18, The experiment ws split-plot rndomized lock design with five nitrogen fertility rte tretments s min plot, two insect ugmenttion tretments s su-plots, nd five replictions. The five min-plot tretments included pre-loom side-dress pplictions of ugmented nitrogen fertilizer rtes of 0, 50, 100, 150, nd 200 ls N/cre using soil pplictor injection rig on July 16. Pre-tretment soil smples (consisting of three soil cores; 0 to 24-inch depth), were collected from ech of the 25 experiment plots on June 26. Two 10-ft. sections of uniform cotton were flgged in the middle two rows of ech 16-row min-plot tht served s two insect tretment su-plots. The su-plot tretment included two cotton flehopper tretments (5 dults per plnt vs. no flehopper s control), contined in multi-plnt cges, within designted row sections pplied to ech of the five nitrogen rtes two weeks into cotton squring (July 21), the most criticl phenologicl stge of cotton for flehopper mngement in the Texs High Plins, to simulte n cute infesttion of cotton flehoppers. Crop growth nd fruiting ptterns were monitored during the crop seson. Results: Two weeks into squring, experimentl plnts hd pproximtely 9 squres per plnt. Cotton flehoppers induced ~25% squre scission cross ll N tretments (Fig. 1). All N ugmented plots hd higher lint yields thn on zero N plots, ut the crop response to vrition in N level ws not well defined (Fig. 2). Comined over ll N tretments, the cute infesttion of flehoppers rendered the lint yield reduction from 910 l/cre in the control to 877 l/cre in flehopper plots. Lint yield ws not significntly ffected y ~25% flehopper-induced squre loss t oth zero N nd 200 l/cre plots, either vi pruning of undesirle fruit lod (zero N) or compenstion (200 l N). On the other hnd, lint yield ws significntly lower in flehopper ugmented 100 l/cre plots compred to tht in uninfested plots, clerly suggesting tht the plnt response to cotton flehopper injury is gretly influenced y the villy of nitrogen fertility. Fig. 1. Per plnt squre lod t the time of cotton flehopper ugmenttion (top pnel) nd percent squre scission (ottom pnel) in control versus flehopper ugmented tretments, s influenced y vrile rtes of nitrogen ppliction, Fig. 2. Effect of nitrogen ugmenttion rtes on lint yield following single cute infesttion of cotton flehopper versus uninfested control,

8 TITLE: Cotton yield response to cotton flehopper cute infesttions s influenced y irrigtion level tretments, Lmes, TX, AUTHORS: Megh Prjulee Professor, Fculty Fellow, nd Regents Fellow Adul Hkeem Postdoctorl Associte Sen Coyle Technicin Chndr Dhkl Reserch Assistnt Stnley Crroll Reserch Scientist Wyne Keeling - Professor MATERIALS AND METHODS: Plot Size: 4 rows y 300 feet, 3 replictions Plnting dte: My 16, 2015 Fertilizer: Tretments: Cultivr: Irrigtion: Cotton flehopper: Deltpine 1454 B2RF FierMx 2011 GT Low: Pre-plnt = 0.8 inches; In-seson = 3.6 inches High: Pre-plnt = 0.8 inches; In-seson = 7.1 inches 2 insect stges (dults vs nymphs); 3 insect relese tretments [control (zero cotton flehopper), low flehopper density (2 ugs per plnt), high flehopper density (5 ugs per plnt), Hericides: Roundup PowerMx 1qt/A Jnury 28 Roundup PowerMx 1 qt/a + 2,4-D 1 qt/a April 9 Prowl 3 pt/a April 21 Roundup PowerMx 1 qt/a June 11 Roundup PowerMx 1 qt/a + Dul Mgnum 1 pt/a July 13 Insect relese dte: Plnt mpping dte: Hrvest dte: July 2, 2015 (flehopper susceptile stge) July 22, 2015 (in-seson); Octoer 14, 2015 (pre-hrvest) Octoer 26, 2015 (hnd-hrvested) Cotton flehopper feeding injury nd resulting cotton lint yield were evluted in two cotton cultivrs, s ffected y irrigtion level, insect stges, nd infesttion densities. Two sesonl irrigtion levels were evluted, High (7.9 ) nd Low (4.4 ), under center pivot irrigtion system. Lortory-rered nd/or field collected cotton flehoppers were relesed onto cotton terminls in 3-ft. (L) x 2-ft. (W) x 3 ft. (H) multi-plnt cges (dults; Fig. 1) or in the 3-ft sections of cotton rows on open field (nymphs). Ech section contined 7 plnts. Experimentl design consisted of two insect stges (dults versus nymphs), three insect relese tretments (high, low, nd control), two wter levels (high versus low), nd two cotton cultivrs (DP 1454 B2RF nd FM 2011 GT), replicted three times nd deployed in rndomized 4

9 complete lock design (totl 72 plots). Insect relese tretments, 1) control (zero flehopper ugmenttion), 2) two ugs per plnt (low density), nd 3) five ugs per plnt (high density), were deployed on July 2, 2015 (Fig. 1), nd then llowed to feed for one week in order to mimic nturl erly-seson cute infesttion. A single relese of cotton flehoppers ws timed to simulte the cute infesttion of cotton flehoppers while cotton ws highly vulnerle to the flehopper injury, which is pproximtely round the second week of cotton squring. Plnt mpping ws conducted efore nd fter cotton flehopper releses to monitor for ltered fruiting ptterns. Yield monitoring ws chieved vi hnd-hrvesting of ech experimentl plot on Octoer There ws no nturl infesttion of cotton flehoppers t the experimentl frm, so the control plots did not require ny insecticidl intervention. Post-relese dt collection included plnt mpping on July 22, pre-hrvest complete plnt mpping on Octoer 14, nd hrvesting on Octoer 26, RESULTS AND DISCUSSION: Averged cross cultivrs, irrigtion levels, nd insect stges, rtificil ugmenttion of cotton flehoppers cused 7.5 nd 12.2% squre loss following low nd high levels of infesttions, respectively, compred to 3.9% squre loss in control plots (Fig. 2). This level of squre loss in pre-flower cotton is considered low to moderte level of insect-induced erly fruit loss in Texs High Plins cotton. Overll, insect-induced squre loss did not vry etween the two cultivrs, ut cotton flehopper nymphs cused significntly greter squre loss compred to the dults. Interestingly, there ws significnt cultivr x insect stge interction in squre loss phenomenon; with significntly greter dmge y nymphs in DP 1454 B2RF thn dults while nymphs nd dults cused similr dmge to FM 2011 GT (Fig. 2). Flehopper crop dmge, s mesured y cotton squre loss, did not significntly vry etween the two wter levels. Although the crop ws t highly cotton flehopper susceptile stge, the ugmented cotton flehopper densities of 2 nd 5 per plnt cused lower levels (7.5 nd 12.2%) of fruit scission thn we hd nticipted. Nevertheless, lint yield ws significntly impcted y the flehopper ugmenttion tretment, with significntly lower yields in flehopper-ugmented plots (Fig. 3). Lint yield vlues were 1415, 1233, nd 1149 l/cre in control, low, nd high ug density tretments in high wter plots nd 1005, 890, 983 l/cre in low wter tretment plots, respectively (Fig. 4). The effect of flehopper on lint yield ws significnt under high irrigtion plots, ut no significnt effect of cotton flehopper ws oserved in low irrigtion plots, indicting plnts from low irrigtion plots llowed for lowering of the fruit lod vi insectinduced fruit loss. Figure 1. Multi-plnt cges deployed in the field to exmine the impct of cotton flehopper densities on cotton yield, Lmes, TX. 5

10 Figure 2. Averge percentge squre loss following simulted cute infesttion of cotton flehoppers, chieved y ugmenting 2 (low) nd 5 (high) ugs per plnt during the second week of squring, under low nd high irrigtion regimes in two cotton cultivrs, Lmes, Texs, Figure 3. Averge lint yield following simulted infesttion of cotton flehoppers, chieved y ugmenting 2 (low) nd 5 (high) ugs per plnt during the second week of squring, under low nd high irrigtion regimes in two cotton cultivrs, Lmes, Texs, Figure 4. Averge lint yield following simulted cute infesttion of cotton flehoppers under high nd low irrigtion regimes, Lmes, Texs,

11 ANNUAL REPORT 2015 Cotton Incorported Core Progrm Project Numer: Evlution of Cotton Flehopper Dmge Potentil nd Crop Response to Injury under Vrile Nitrogen Fertility Level Sumitted y: Megh N. Prjulee Professor, Fculty Fellow, nd Regents Fellow Texs A&M AgriLife Reserch nd Extension Center 1102 Est FM 1294 Luock, TX (806) Coopertors: Adul Hkeem, Postdoctorl Reserch Associte Sen Coyle, Technicin Stnley Crroll, Reserch Scientist 7

12 Evlution of Cotton Flehopper Dmge Potentil nd Crop Response to Injury under Vrile Nitrogen Fertility Level Project Summry The cotton flehopper, Pseudtomoscelis seritus (Reuter), is significnt economic pest of cotton in the Texs High Plins. Injury y cotton flehoppers to squring cotton often cuses excessive loss of smll squres during the erly fruiting period of plnt development (first 3 weeks of squring). Both dults nd immtures feed on new growth, including smll squres. Greter dmge is oserved on smooth lef vrieties thn on hirsute vrieties, which my extend the susceptile period into erly loom, especilly under high-input production regime. Cotton is ffected y cotton flehopper injury from out the fifth true-lef through first week fter initition of flowering. Squres up to pinhed size re most susceptile to dmge, nd yield loss is most likely from feeding during the first three weeks of fruiting. Cotton flehopper dmge lso delys crop mturity nd thus increses the vulnerility of cotton to lte seson pests such s heliothine cterpillrs nd Lygus ugs. The ojective of this study ws to evlute the cotton crop growth prmeters nd lint yield following cotton flehopper cute infesttions under rnge of nitrogen fertility rtes. The five min-plot tretments included pre-loom side-dress pplictions of ugmented nitrogen fertilizer rtes of 0, 50, 100, 150, nd 200 ls N/cre using soil pplictor injection rig on 23 July 2014 nd 16 July The su-plot tretment included two cotton flehopper ugmenttion tretments [5 cotton flehopper nymphs (2014) or dults (2015) per plnt versus no flehopper ugmenttion s control] pplied to ech of the five nitrogen fertility rtes two weeks into cotton squring, the most criticl phenologicl stge of cotton for cotton flehopper mngement in the Texs High Plins. Cotton flehopper infesttion tretments cused 14-27% nd 24-26% squre loss in 2014 nd 2015, respectively. Cotton flehopper induced fruit loss resulted in significnt crop mturity dely in 2014, s mesured y numer of unopened olls (7.7% non-hrvestle olls in the infested plots versus 1.8% in control plots) t hrvest. There ws no mturity dely penlty in 2015 due to n unsesonly wrmer fll. As expected, lint yield vried with N level regrdless of the cotton flehopper infesttion in oth yers. In uninfested control plots, lint yield displyed chrcteristic stircse effect of nitrogen rte, with lowest lint yield (862 l/cre) in zero N nd highest lint yield (1,081 l/cre) in 200 N tretments, with numericl increse in lint yield for ech incrementl nitrogen ppliction of 50 l/cre. In 2015, ll N ugmented plots hd higher lint yield thn on zero N plots, ut the N density response ws not well defined. Comined over ll N tretments, the cute infesttion of cotton flehoppers rendered the lint yield reduction from 975 nd 910 l/cre in the uninfested control to 846 nd 877 l/cre in flehopper ugmented tretments in 2014 nd 2015, respectively. In oth yers, cotton lint yield ws not significntly ffected y ~25% flehopper-induced squre loss three weeks into squring t oth zero N nd 200 l/cre plots, either vi pruning of undesirle fruit lod (zero N) or compenstion (200 l N), wheres lint yield ws significntly lower in flehopper ugmented 100 l/cre plots compred to tht in uninfested plots, clerly suggesting tht the plnt response to cotton flehopper injury is gretly influenced y nitrogen fertility. 8

13 Introduction The cotton flehopper, Pseudtomoscelis seritus (Reuter), is significnt economic pest of cotton in the Texs High Plins. Injury y cotton flehoppers to squring cotton often cuses excessive loss of smll squres during the erly fruiting period of plnt development (first 3 weeks of squring). Both dults nd immtures feed on new growth, including smll squres. Greter dmge is oserved on smooth lef vrieties thn on hirsute vrieties (Knutson et l. 2013), which my extend the susceptile period into erly loom, especilly under high-input production regime. Cotton is ffected y cotton flehopper injury from out the fifth true-lef through first week fter initition of flowering. Squres up to pinhed size re most susceptile to dmge, nd yield loss is most likely from feeding during the first three weeks of fruiting (Reinhrd 1926). Cotton flehopper dmge lso delys crop mturity nd thus increses the vulnerility of cotton to lte seson pests such s heliothine cterpillrs nd Lygus ugs, prticulrly when nturl enemies re destroyed y insecticides directed ginst cotton flehoppers (Chen et l. 2007). Predominntly, cotton flehoppers feed upon pinhed-sized or smller squres, which results in ortion of these young fruits, therey impcting yields. While cotton flehopper feeding preferences serve s seline for their mngement in cotton fields, detiled understnding of cotton plnt responses to flehopper dmge remins unchieved (Prjulee et l. 2006, Chen et l. 2007). Cotton plnt growth is sensitive to numerous environmentl nd mngement input fctors, prticulrly irrigtion nd nitrogen fertility. Cotton growth responses to vrious input fctors re well-documented nd growth models hve een developed. However, the specific cotton plnt responses to cotton flehopper injury under rnge of nitrogen fertility remin uninvestigted. This study ws designed to evlute the cotton crop growth prmeters nd lint yield following cotton flehopper cute infesttions under rnge of nitrogen fertility rtes. Mterils nd Methods This study ws conducted t the Texs A&M AgriLife Reserch frm ner Plinview, Texs. A 5-cre susurfce drip irrigtion system hs een in plce for 14 yers nd nitrogen fertility tretments hve een pplied in rndomized lock design with five replictions since 2002 (Fig. 1). The present study utilized the sme experimentl set up s for the lst 13 yers. Preplnt lnd preprtions on the field of 30-in row-spcings included n ppliction nd incorportion of Trefln 2 pints/cre on 19 Ferury 2014 nd 12 Jnury, The field did not receive pre-plnt fertility pplictions. The 2014 study ws plnted with FierMx 9063 B2R t trgeted rte of 54,000 seeds/cre on 16 June nd post-emergence hericide tretments were pplied on 27 June (Crop 32 oz/cre; 3 pints/cre) nd 7 July (Crop 40 oz/cre). The 2015 test ws plnted to Fiermx 9180 B2F t trgeted rte of 60,000 seeds/cre followed y n over-thetop Cprol 4L (prometryn; 3 pints/cre) ppliction immeditely fter plnting on 18 My, with post-emergence hericides pplictions on 30 June 32 oz/cre) nd 29 July (Wrrnt 3 pt/cre) for weed mngement. Experimentl plots were 16 rows wide x 120 ft long nd 5 ft lleys seprted the plots. The experiment ws split-plot rndomized lock design with five nitrogen fertility rte tretments s min plot, two insect ugmenttion tretments s su-plots, nd five replictions. The five min-plot tretments included pre-loom side-dress pplictions of ugmented nitrogen fertilizer rtes of 0, 50, 100, 150, nd 200 ls N/cre using soil pplictor injection rig on 23 July

14 nd 26 June The individul plots hve een receiving the sme nitrogen ugmenttion rtes for the pst 14 yers. The pre-tretment residul nitrogen soil smples were pulled on 10 July 2014 nd 26 June 2015 from ech of the 25 experimentl plots. The soil smples were quickly plced into n unused greenhouse to quickly remove the soil moisture. These dried smples were processed through soil grinder prior to shipment to Wrd Lortories (Kerney, NE) for residul nitrogen nlyses. The five fertility tretment pplictions were pplied y sidedressing the 25 experimentl plots with the pproprite nitrogen levels on 23 July 2014 nd 16 July Two 10-ft. sections of uniform cotton were flgged in the middle two rows of ech 16-row min-plot tht served s two insect tretment su-plots. The su-plot tretments included two cotton flehopper ugmenttion tretments (5 cotton flehopper nymphs per plnt uncged [2014] or 5 cotton flehopper dults per plnt in multi-plnt cges [2015] versus no flehopper ugmenttion s control) pplied to squring cotton within these designted row sections to simulte n cute infesttion of cotton flehoppers. This erly squring period is the most criticl phenologicl stge of cotton for cotton flehopper mngement in the Texs High Plins (Prjulee et l. 2006). Woolly croton ws hrvested from rngelnd sites ner College Sttion, Texs, in erly Ferury nd then plced into cold storge. Forty 1-gllon sheet metl cns (ends of cylinder-type cns covered with window screen), ech contining 4 ounces of dry croton twigs per cn, were initited to generte the required numer of cotton flehoppers for the experiment (Hkeem nd Prjulee 2015). Conditions conducive to cotton flehopper emergence were simulted in lortory environment in order to induce htching of overwintered eggs emedded in the croton stems, nd emerged cotton flehoppers were susequently rered on fresh green ens. Field collected cotton flehopper dults ugmented the lortory colony in The single relese of cotton flehoppers (nymphs in 2014 nd dults in 2015) mentioned ove ws timed to simulte the cute hevy infesttion of cotton flehoppers (4-5 dys of feeding) while cotton ws highly vulnerle to the flehopper injury. It ws plnned so tht this rrngement would ensure significntly high levels of flehopper-induced squre dmge on tretment plots to quntify the vrition in dmge potentil s influenced y soil pplied N. The relese ws ccomplished on 30 July 2014 nd 21 July 2015 y spirting third-instr flehopper nymphs or dults from the lortory rered nd/or dpted colonies, trnsferring them into 0.75 X 1.5 plstic vils, then cutiously depositing them onto the terminls of plnts in ech tretment plot t the rte of 5 cotton flehoppers per plnt; the control plots received no flehoppers nd were kept flehopperfree during the entire study period. Nturl infesttions of cotton flehoppers did not occur t our site due to the severe crop dely in 2014 nd frequent rin showers in Therefore, the control sections within ech of the 25 plots in 2014 did not receive supplementl insecticidl interventions until n Orthene 97UP insecticide ppliction ws pplied on 7 August 2014 to ll experimentl units (oth flehopper relese sections nd control sections within ech of the 25 min-plots) to ensure complete removl of ll cotton flehoppers following their relese nd feeding period. For 2015 study, 7-plnt unit ws cged within the mrked cotton row sections nd dult cotton flehoppers were relesed in ech cge, ut the cging of dult tretment section with lrge cges for <7 dys ws expected to hinder the plnt growth minimlly. Seven dys fter cotton flehopper ugmenttion, the entire test ws spryed with Orthene 12 oz cre on 28 July In oth yers, the entire test ws kept insect-free for the reminder of the study to isolte the effect of cotton flehopper injury only. All control nd flehopper-ugmented sections were monitored for flehopper-induced fruit loss on 14 August 2014 nd 6 August

15 Additionl dt collected included monitoring of plnt height, lef chlorophyll content, lef nitrogen content, nd squring ptterns in ll 50 experimentl units (5 N rtes x 2 insect tretments x 5 replictions), strting from the first week of squring (pre-relese dt) nd pproximtely weekly therefter well into the fll crop developmentl period. The dtes in which ten 5 th min stem leves (from the plnt top) were collected for chlorophyll redings, lef re mesurements, lef dry weights, nd end-of-study lortory lef nitrogen nlysis in 2014 included 25 July; 5, 22, nd 28 August; 5 nd 26 Septemer; nd 2 nd 8 Octoer 2014; the 2015 smples dtes for these prmeters were 30 July; 6, 13, 20, nd 27 August; nd 4 nd 11 Septemer In-seson plnt mpping nd plnt height dt from five rndomly selected plnts per plot were collected on 26 August 2014 nd 30 July Five rndomly selected plnts in ech of the 25 experimentl plots (125 totl plnts) were dug-up nd returned to the lortory for mesurement of detiled individul plnt iomss of the following: 1) root, 2) shoot, 3) leves, nd 4) fruits. Lter on 26 Septemer 2014 nd 20 August 2015, 15 rndomly selected olls were collected from the 5 th minstem node from the top of the plnts nd then the 375 totl olls (15 olls per plot X 25 plots) were plced into n ice chest nd returned to the lortory to mesure oll prmeters including: 1) oll dimeter, 2) oll fresh weight, 3) oll crpel wll puncture pressure, nd 4) oll dry weight following plcement into drying oven. The timing of crop cut-out within individul plots ws estimted y counting the Nodes Aove White Flower (NAWF) on series of rndomly selected plnts per plot on 28 August; nd 5 nd 19 Septemer 2014 nd 10, 13, 20, nd 27 August; nd 4 nd 11 Septemer The 2014 test ws prepred for hrvest y first sprying oll opener (Boll Buster 1 qurt per cre) nd defolint [ET (pyrflufen) 1.25 oz per cre] in tnk mix on 23 Octoer, followed y n ppliction of desiccnt (Helmqut 3SL 1 qurt per cre) to finish terminting the cotton plnts on 3 Novemer The 2015 test ws terminted y sprying oll opener (Boll Buster 1 qurt per cre) nd defolint [ET (pyrflufen) 1.25 oz per cre] in tnk mix on 14 Octoer, followed y n ppliction of desiccnt (Helmqut 3SL 1 qurt per cre) to terminte the plnts on 29 Novemer Finl plnt mpping nd hrvesting of test sections were performed on 20 Novemer 2014 nd 2 Novemer 2015 nd the ginned lint smples were sent to Cotton Incorported for fier qulity nlysis. Figure 1. Helms Frm nitrogen study experimentl plot lyout following five-tretment x fiverepliction rndomized lock design. Ech of the 25 plots received one of the five nitrogen ugmenttion tretments including 0, 50, 100, 150, or 200 ls N/cre, Hle County, TX. 11

16 Results nd Discussion Influence of N fertility level on cotton plnt growth prmeters. Soil residul N levels were much higher in 2014 compred to tht in 2015 (Fig. 2). The unusul hevy rinfll throughout spring of 2015 likely leched excess residul nitrogen uild-up from prior yers of drought conditions, resulting in much lower residul N in Residul N levels generlly incresed with incresed level of pplied N. In 2014, residul N levels were significntly higher in plots tht received the two highest ppliction rtes of N fertilizer versus plots receiving 50 l/cre N pplictions or no N ugmenttion; plots tht received 100 l N/cre hd n intermedite level of residul nitrogen (Fig. 2). The two highest N ugmenttion plots (150 nd 200 l/cre) resulted in three-times higher mount of soil residul N compred to tht in zero nd 50 l/cre plots. In 2015, plots receiving 150 nd 200 l/cre N hd ccumulted significntly higher residul N compred to tht in zero nd 50 l/cre N plots. These experimentl plots hd een receiving sme ssigned levels of pplied N for the previous 13 yers nd the reltionship etween pplied N rtes nd resulting residul N hs generlly followed this trend for ll previous yers. Vrition in residul N did not show significnt vrile effect on erly cotton growth prmeters, such s plnt height, lef re, nd chlorophyll content. However, the effect of N ppliction rte ws more pronounced s the seson progressed, especilly in drier yer such s 2014 (Fig. 3). However, in wet yer such s 2015, the effect of N ppliction rte did not vry temporlly within the seson (Fig. 4). In 2014, the effect of N ppliction rte ws less pronounced in lef surfce re compred to tht for chlorophyll concentrtion nd lef N content of the fifth minstem node lef. Mesured lef chlorophyll content vried with nitrogen ppliction level, nd lef chlorophyll contents from cotton in those plots which received 0 l N/cre were significntly lower thn ll others (Figs. 3-4). Chlorophyll concentrtion in zero N plots ws 5 or more units lower thn tht for 50 l N/cre plots throughout the growing seson, while the concentrtion further declined s the seson progressed, especilly in In 2015, ll N ugmented cotton plots exhiited reltively consistent lef prmeters ut significntly vried to tht in zero N plots (Fig. 4). It is noteworthy tht the lef chlorophyll content in zero N tretment plots declined precipitously eginning in lte August, when plnts egn llocting much of their resources to oll mturtion, wheres this phenomenon did not occur in plots tht received 50 l N/cre. In 2014, percentge lef nitrogen declined s the seson progressed, especilly when plnts egn diverting their energy to fruit mturtion (mid- to lte August). However, the lef nitrogen content in zero N plots egn to decline soon fter cotton egn flowering, ut it declined much more rpidly in zero N plots thn for N ugmented plots when plnts egn llocting much of their resources to oll mturtion (Fig. 3). In 2015, percentge lef nitrogen did not vry significntly s seson progressed, ut the lef nitrogen content in zero N plots remined consistently lower thn tht for N ugmented plots (Fig. 4). Plnt prmeter vlues such s plnt height, lef re (lef size), lef chlorophyll concentrtion, nd percentge lef nitrogen were much lower in zero N plots compred to tht in ll N ugmented plots y the time crop ttined full mturity (Figs. 5-8), indicting high degree of physiologicl stress on plnts receiving zero pounds of ugmented nitrogen. Lower rtes of N ugmenttion resulted in lower plnt prmeter vlues compred to tht for high rtes of N ugmenttion. 12

17 Vrile rtes of N ugmenttion ffecting plnt height, lef size, lef chlorophyll, nd lef nitrogen content correspondingly impcted lef dry weight nd oll dry weight t full crop mturity. Fifth minstem lef dry weight ws significntly lower t zero N plots (Figs. 8-9). Lef dry-weight vlues were similr in ll N ugmented plots lthough the two lower N ugmented tretments (50 nd 100 l/cre) hd numericlly lower lef dry weight compred to tht for two highest N rtes. Nitrogen fertility level lso influenced oll mturity. Plnts in zero N plots dvnced to reproductive phse erlier nd olls formed nd mtured significntly erlier thn in N ugmented plots. As result, dry weight of fifth minstem node olls ws significntly greter in zero N plots compred to tht for N ugmented plots (Fig. 9). Lortory mesurement of oll exocrp penetrility in 2014 showed tht the fifth minstem node olls from zero N ugmented plots required significntly greter pressure to puncture the exocrp versus tht required to do so for olls from N ugmented plots; however, hevy nd frequent rin events in 2015 eliminted the moisture stress in zero N plots during erly oll development phse, resulting in no significnt penetrility differences in olls cross ll N tretments (Fig. 10). Vrition in soil residul N levels, coupled with vrile N ppliction, resulted in phenotypic expression of nitrogen deficiency in cotton cross tretment plots, more pronouncedly etween zero N plots nd N ugmented plots, which were reflected on temporl chlorophyll contents of the fifth lef (Fig. 3). However, such phenotypic expression of N deficiency in zero or low N level tretments ws not oserved in N fertility level nd cotton flehopper infesttion. Cotton plnts were two weeks into squring when n cute infesttion of 5 cotton flehoppers per plnt ws deployed. Pre-relese monitoring of squring profiles showed tht plnts hd ~6 (2014) to ~9 (2015) squres per plnt cross ll N tretments. Totl squre density did not vry with N tretments prior to cotton flehopper infesttion (Figs ). This density (5 cotton flehoppers per plnt) is considered equivlent of 1 cotton flehopper per plnt, with 20% field survivorship nd visul oservtion retrievl of relesed nymphs or dults. The density is lso equivlent to 3-4 times current cotton flehopper threshold (25-30 cotton flehoppers per 100 plnts) for the Texs High Plins. One week of cotton flehopper infesttion resulted in significnt squre scission in cotton flehopper ugmented plots, ut negligile squre scission (2-4% or less) ws oserved in uninfested control plots (Figs ). While totl squre density did not vry cross N tretments, cotton flehopper-induced squre scission levels vried significntly with N ppliction rtes in 2014, ut it did not vry cross N tretments in In generl, higher N rte fvored lesser impct of cotton flehopper injury. In 2014, squre scission rte ws numericlly highest t zero N plots, followed numericlly y 50 nd 100 l N/cre plots, yet ll vlues were sttisticlly similr. However, scission rtes were reduced to 19 nd 14% in 150 nd 200 N tretments, respectively (Fig. 11). In 2015, squre scission rtes were similr t ~25% cross ll N tretments (Fig. 12). No iologicl or physiologicl resons re speculted for reduced squre scission oserved in the two highest N rte plots in In 2014, cotton flehopper infesttion cused noticele crop mturity dely, s mesured y numer of unopened olls (non-hrvestle olls) present t hrvest. Averged cross ll N tretments, percentge unopened olls were 7.7% in cotton flehopper ugmented plots compred with 1.8% unopened olls in uninfested (control) plots; N ugmenttion levels did not significntly influence the percentge oll opening t the time of hrvest (Fig. 13). Nevertheless, 13

18 ecuse the level of squre scission ws not excessive (14-27%) for pre-flower cotton (75% fruit set is considered lower limit for Texs High Plins cotton into the third week of squring), the crop did not suffer mjor crop mturity dely due to cotton flehopper infesttion. The 2015 crop seson ws chrcterized y frequent rin events throughout the spring nd erly summer months, followed y reltively wrmer nd extended fll, which llowed for full crop mturity cross ll N ppliction regimes. As expected, lint yield vried with N level regrdless of the cotton flehopper infesttion (Figs ). In uninfested control plots in 2014, lint yield displyed chrcteristic stircse effect of nitrogen ppliction rte, with lowest lint yield (862 l/cre) in zero N nd highest lint yield (1,081 l/cre) in 200 N tretments, with numericl increse in lint yield for ech incrementl nitrogen ppliction of 50 l/cre. In 2015, ll N ugmented plots hd higher lint yield thn on zero N plots, ut the crop response to vrition in N density ws not well defined. Comined over ll N tretments, the cute infesttion of cotton flehoppers rendered the lint yield reduction from 975 l/cre nd 910 l/cre in the uninfested control to 846 l/cre nd 877 l/cre in flehopper ugmented tretments in 2014 nd 2015, respectively. In oth yers, cotton lint yield ws not significntly ffected y ~25% flehopper-induced squre loss three weeks into squring t oth zero N nd 200 l/cre plots, either vi pruning of undesirle fruit lod (zero N) or compenstion (200 l N). On the other hnd, lint yield ws significntly lower in flehopper ugmented 100 l/cre plots compred to tht in uninfested plots, clerly suggesting tht the plnt response to cotton flehopper injury is gretly influenced y the villy of nitrogen fertility. Figure 2. Effect of prior yers N ppliction (0, 50, 100, 150, nd 200 l per cre) on residul N ccumultion in the soil for the current crop yer,

19 Figure 3. Temporl dynmics of lef growth (lef re), chlorophyll concentrtion, nd percentge lef nitrogen content mesured on fifth minstem lef s influenced y the vrile rtes of ugmented nitrogen (l N/cre), Figure 4. Temporl dynmics of lef growth (lef re), chlorophyll concentrtion, nd percentge lef nitrogen content mesured on fifth minstem lef s influenced y the vrile rtes of ugmented nitrogen (l N/cre),

20 Figure 5. Averge lef surfce re (left) nd chlorophyll concentrtion or SPAD vlues (right) of the fifth minstem node lef on full-cnopy crop s ffected y N tretments, August 26, Figure 6. Averge lef surfce re (left) nd chlorophyll concentrtion or SPAD vlues (right) of the fifth minstem node lef on mid-seson crop s ffected y N tretments, August 20,

21 Figure 7. Effect of vrile nitrogen tretments on cotton plnt height t full crop cnopy growth (August 26, 2014) nd mid-seson (July 30, 2015). Figure 8. Effect of vrile nitrogen on fifth minstem lef dry weight, verged over 6 smple weeks during the cotton growing seson, Hle Co., Texs,

22 Figure 9. Effect of vrile nitrogen on fifth minstem lef dry weight nd fifth minstem node oll dry-weight t full crop mturity, Septemer 26, Figure 10. Effect of vrile nitrogen on oll mturity s mesured y the pressure required to puncture the crpel wll of the fifth minstem node position olls, Septemer 26 (2014) nd August 20 (2015). 18

23 Figure 11. Totl squre density (numer of squres set per plnt) t the time of cotton flehopper ugmenttion (top pnel) nd percentge squre scission (ottom pnel) in control versus cotton flehopper ugmented tretments, s influenced y ugmented vrile rtes of nitrogen ppliction (0, 50, 100, 150, nd 200 l per cre), 2014, Hle County, TX. Figure 12. Totl squre density (numer of squres set per plnt) t the time of cotton flehopper ugmenttion (top pnel) nd percentge squre scission (ottom pnel) in control versus cotton flehopper ugmented tretments, s influenced y ugmented vrile rtes of nitrogen ppliction (0, 50, 100, 150, nd 200 l per cre), 2015, Hle County, TX. 19

24 Figure 13. Effect of nitrogen ugmenttion rtes (0, 50, 100, 150, nd 200 l per cre) on cotton mturity s mesured y numer of unopened (non-hrvestle) olls t hrvest, Novemer 20, 2014, Hle County, TX. Figure 14. Effect of nitrogen ugmenttion rtes (0, 50, 100, 150, nd 200 l per cre) on lint yield following single cute infesttion of cotton flehopper versus uninfested control, , Hle County, TX. 20

25 Figure 15. Effect of nitrogen ugmenttion rtes (0, 50, 100, 150, nd 200 l per cre) on cotton lint yield following single cute infesttion of cotton flehopper versus uninfested control, 2014, Hle County, TX. Figure 16. Effect of nitrogen ugmenttion rtes (0, 50, 100, 150, nd 200 l per cre) on cotton lint yield following single cute infesttion of cotton flehopper versus uninfested control, 2015, Hle County, TX. Acknowledgments Cotton Incorported Core Progrm nd Plins Cotton Growers, Inc. provided funding for this study. 21

26 References Chen, C., A. K. Brmn, nd M. N. Prjulee Cotton response to erly squre loss y the cotton flehopper in the Texs High Plins, pp Proceedings, Beltwide Cotton Conf., Ntionl Cotton Council, Memphis, TN. Hkeem, A., nd M. N. Prjulee Moisture conditions for lortory rering of cotton flehoppers from overwintered eggs lid on woolly croton plnts. Southwestern Entomologist 40: Knutson, A., K. Mekl, C. W. Smith, nd C. Cmpos Tolernce to feeding dmge y cotton flehopper (Hemipter: Miride) mong genotypes representing dpted germplsm pools of United Sttes uplnd cotton. J. Econ. Entomol. 106: Prjulee, M. N., R. B. Shresth, nd J. F. Leser Influence of tillge, plnting dte, nd Bt cultivr on sesonl undnce nd within-plnt distriution ptterns of thrips nd cotton flehoppers in cotton. Int. J. Pest Mnge. 52: Reinhrd, H. J The cotton flehopper. Texs Agric. Exp. St M Bull. 339, Agriculturl nd Mechnicl College of Texs, College Sttion, TX. 22

27 PROJECT FINAL REPORT Cotton Incorported/Texs Stte Support Progrm Project Numer: TX Development of Economic Threshold nd Mngement Recommendtions for Lygus in Texs High Plins Cotton Sumitted y: Megh N. Prjulee Texs A&M AgriLife Reserch 1102 Est FM 1294 Luock, TX (806) Coopertors: Adul Hkeem, Postdoctorl Reserch Associte Sen Coyle, Technicin Stnley C. Crroll, Reserch Scientist 23

28 Development of Economic Threshold nd Mngement Recommendtions for Lygus in Texs High Plins Cotton Megh N. Prjulee, Texs A&M AgriLife Reserch nd Extension Center, Luock PROJECT SUMMARY Western trnished plnt ug, Lygus hesperus, is the primry Lygus species inhiting cotton nd severl other crop hosts in the Texs High Plins. In Texs High Plins cotton, Lygus is generlly more pestiferous in the oll development stge thn in erly squring stge. Our recent study on oll dmge ssessment sed on het unit-delineted mturity provided oll-sfe cutoff vlue of 350 het units (~2-3 weeks from flowering), lthough Lygus dults nd nymphs oth cuse externl lesions on olls throughout oll development nd my give frmers flse impression of Lygus dmge. A four-yer Stte Support funded project reveled tht lte-instr nymphs cused significntly more dmge to mturing olls thn dults, nd inflicted 23, 29, nd 15% more loss in lint yield, seed weight, nd seed counts per oll, respectively, versus dults. Nevertheless, no economic threshold for Lygus oll mngement hs een developed for Texs cotton. The mjor gol of this project ws to develop economic threshold-sed mngement recommendtions for Lygus in Texs High Plins cotton, therey iming to minimize economic losses to producers. Specific ojectives were to: 1) determine the mximum potentil for Lygus to inflict dmge to cotton olls t vrious oll mturity levels (ges), 2) chrcterize the cotton oll preference ehvior of Lygus, nd 3) estlish the Lygus economic threshold for Texs cotton. Boll dmge potentil of Lygus hesperus ws determined in no-choice cup-cge study. Ten cohorts of cup-cged single olls (1-20 dys old) were ech exposed to Lygus dult for 48 hours nd the oll dmges were quntified. After olls reched out two weeks of ge, Lygus cused very little seed dmge, which s expected, lso did not result in significnt lint yield loss. Cotton olls were sfe from Lygus dmge when they reched >28 mm dimeter or their crpel wll hrdness ws 0.7 l per squre foot or greter. Cotton oll feeding preferences of Lygus hesperus, within-plnt oll distriution profile, nd Lygus dmge to cotton olls t vrious Lygus densities were determined in whole-plnt nd multi-plnt cge field studies. Cged cotton plnts were exposed to five levels of Lygus (0, 1, 2, 4, nd 6 dults per plnt) for one week when plnts were t two selected oll development stges (350 nd 550 HU fter first flower). When the crop mtured from 350 HU to 550 HU fter first flower, the percentge of olls vulnerle to Lygus feeding dmge ws reduced from 50% to 30%. Internl wrts were mostly limited to the olls mesuring <35 mm in dimeter. In this open-choice oll feeding sitution, Lygus preferred to feed on olls tht were mm in dimeter. Averged over four yers, on 1,200 l/cre crop, rtificil ugmenttion of 1, 2, 4, nd 6 Lygus per plnt t 350 HU fter first flower reduced the cotton lint yield y 199, 271, 407, nd 433 l/cre, respectively, wheres the yield reduction vlues for the sme Lygus densities were 52, 142, 229, nd 269 l/cre during the lte seson (550 HU from first flower). Thus, the Lygus yield reduction potentil significntly decresed when cotton mtured from 350 HU to 550 HU, with 71 l/cre lint reduction per Lygus per plnt infesttion in lte seson compred with 127 l/cre lint reduction per Lygus per plnt in mid-seson. Bsed on this study, Lygus mngement options for Texs High Plins cotton fter the initition of first flower re recommended s follows: creful monitoring of cotton crop nd djcent hitts for Lygus undnce nd movement ehvior nd voidnce of insecticide tretment for Lygus in cotton prior to 200 HU from first flower, 2-4 Lygus per 6 row-ft for mid-seson cotton, nd 4-6 Lygus per 6 row-ft for lte seson cotton. 24

29 Introduction Cotton, Gossypium hirsutum L., is mjor csh crop in the U.S. nd worldwide. The U.S. is the world s third lrgest cotton producer nd the U.S. cotton industry is vlued t more thn 25 illion dollrs per yer. In Texs, pproximtely six million cres of cotton hve een plnted nnully in recent yers, nd Texs is the lrgest cotton producing stte (Willims 2013). Lygus hesperus is n importnt economic pest of cotton in some regions of the United Sttes nd it is n emerging pest of Texs High Plins cotton. In 2012, 2.04% reduction in U.S. cotton yields ws ttriutle to rthropod pests 0.7% due to Lygus species, which ws rnked top mong other yield-reducing pests (Willims 2013) nd lso cost more per infested cre ecuse multiple pplictions were often required. In Texs, over 2 million cres of cotton were infested y Lygus in 2012 (Willims 2013). Lygus cn cuse severe cotton squre loss, nther dmge, nd seed dmge depending upon the crop growth stge the infesttion occurs. Both dult nd nymphl stges of Lygus cn inflict dmge to cotton fruiting structures. Lygus lte-instr nymphs re cple of inflicting greter internl dmge to mturing olls thn re dults, nd this ws especilly true for 1-2 week old ( HU) olls (Ju nd Crruth 1971, Prjulee et l. 2011). In the Texs High Plins region, Lygus generlly infest cotton fields during the ltter prt of the cropping seson, thus cusing mostly dmge to the cotton olls. Following the introduction of Bt-technology (Bollgrd cotton), outreks of lepidoptern pests hve een drsticlly reduced, nd in recent yers, secondry piercing-sucking pests such s Lygus re of incresing concern to Texs High Plins producers (Prjulee et l. 2008). Cotton oll profiles chnge s crop mtures, nd s result, the numer of Lygus susceptile nd/or tolernt olls to Lygus dmge lso chnge. As oll mturity profiles chnge, Lygus oll selection nd feeding ehvior my lso chnge which cn result in different levels of crop injury nd yield loss. There is strong reltionship etween oll mturity nd Lygus feeding dmge, thus understnding the oll mturtion profile nd chrcterizing Lygus dmge risk dynmics is very importnt. Becuse relile Lygus-resistnt or tolernt cotton cultivrs re unville, cotton producers primrily rely on pesticides for Lygus mngement. Current pesticide ppliction decisions re sed on field scouting, wherey spry pplictions re typiclly wrrnted when Lygus popultions exceed loclly estlished economic threshold (ET) levels. Oosterhuis nd Kim (2004) reported tht cotton olls tht ccumulted het units were sfe from piercing-sucking insects. It is expected tht Lygus hesperus my lso e unle to dmge cotton olls once certin oll mturity level hs een reched, fter which pesticide pplictions would not e necessry. However, the ctul oll dmge potentil of Lygus hesperus is lrgely unknown. One importnt question in this study ws: At wht point do mturing olls or the entire crop ecome sfe from Lygus feeding dmge, nd, consequently, when does insecticide use ecome unnecessry? Given the vilility of tools to identify when the olls re sfe, timing of insecticide use termintion my e refined to minimize unnecessry economic nd ecologicl costs. The ojectives of our field experiments were to: 1) determine the mximum potentil for Lygus to inflict dmge to cotton olls t vrious oll mturity levels (ges), 2) determine the cotton oll mturity profile during two oll development stges (t 350 nd 550 HU After First 25

30 Flowering [AFF]), 3) determine the oll feeding preference of Lygus hesperus dults s ffected y the chnge in oll mturity profile s the crop mtures from 350 HU to 550 HU AFF, nd 4) quntify the yield loss cused y five different levels of Lygus infesttions (0, 1, 2, 4, nd 6 Lygus dults per plnt). The overll gol ws to etter understnd the oll feeding iology nd ehvior of Lygus hesperus in order to further develop dynmic economic threshold for improved Lygus mngement in Texs High Plins cotton. Estimting Lygus Boll Dmge Potentil Mterils nd Methods A field study to quntify dult Lygus hesperus cotton oll dmge potentil ws conducted t the Texs A&M AgriLife Reserch nd Extension Center frm locted ner Luock, Texs. Cotton cultivr ST5458B2RF ws plnted on My 18 (2012), My 22 (2013), nd My 15 (2014), nd ST4946GLB2 on June 3 (2015) in drip-irrigted field with 40-inch row spcing. The trgeted seeding rte ws 56,000 seeds per cre. On June 2, the 2012 study ws treted with Orthene 97S for thrips t rte of 3.0 oz per cre nd with Cornerstone Plus hericide (41% glyphoste) t 32 oz per cre for weed mngement, wheres the 2013 nd 2014 study plots did not receive insecticide interventions for thrips control nd weeds were removed vi hnd-hoeing. In 2015, 32 oz/cre nd Wrrnt 3 pt/cre were pplied on June 30 nd July 29, respectively, for weed mngement Study. The experimentl design ws split-plot rndomized lock with three replictions. Ten cotton oll ge cohorts (1 to 20 dys from flowering t 1-dy increment) served s the min plot nd two Lygus infesttion levels (I: one dult Lygus feeding for 48 hours, nd II: control or zero ugs) served s suplots. Thus, there were 30 min plots (3 locks x 10 oll ge cohorts), ech of which consisted of 100 ft long cotton rows. In ech min plot, 20 rndomly selected white flowers were individully cup-cged using modified polystyrene fom nd cloth-net cup cges (Fig. 1). Thus, totl of 600 white flowers were cup-cged (30 min plots x 20 flowers per min plot). Two tretment levels (control nd single Lygus ug infesttion) were pplied in ech min plot. Ech plot contined 20 cup-cged olls of which 5 olls were used s controls, nd the remining 15 olls were exposed to Lygus feeding. Cotton olls in the Texs High Plins region typiclly ccumulte HU per dy in August; thus, in ten dys following cup-cging the fruit, on August 20, the August 1 st cup-cged olls hd received out 450 HU, wheres the August 10 th cup-cged olls hd ccumulted pproximtely 200 HU. Once the cotton olls received HU, individul Lygus dults were relesed in the pproprite cges nd llowed to feed for 48 hours. Lygus dults were initilly rered on rtificil diet, ut were trined on fresh green ens nd cotton squres for week prior to using them for the oll feeding experiment. Prior to relese into the cup-cges, the Lygus dults were strved for 4-5 h. Five Lygus infested olls from ech plot were used for oll size, weight, crpel wll hrdness nd Lygus dmge ssessment (internl nd externl Lygus dmge lesions), while the remining ten Lygus infested olls were kept for yield ssessments. Both control olls nd the olls kept for yield ssessment were hrvested during the first week of Novemer, Study. The study ws deployed in split-plot rndomized lock design with three replictions (locks) to quntify the effect of Lygus density nd infesttion timing on cotton yield nd qulity. The study consisted of two Lygus infesttion levels (one dult Lygus feeding for 48 hours versus zero ugs) s min plot fctors nd ten cotton oll ge cohorts (every-other-dy 26

31 cging of olls from Dy 1 to Dy 20) s suplot fctors. Thus, there were 60 experimentl units. Ech experimentl unit hd eight individully cged olls s susmples, thus, this study comprised of totl of 480 individully cged cotton olls (three locks x two Lygus infesttion levels x ten oll ge cohorts x eight susmples). Cotton field ws divided into three locks. Ech lock consisted of 10 cotton rows, representing 10 oll ge cohorts. Every two dys for period of 20 consecutive dys (July 29 to August 18), one cotton row ( min plot) ws rndomly selected nd twenty rndomly selected new, white flowers were individully tgged, yielding 10 cotton oll ge cohorts. On Dy 21 (August 19), ll 480 olls were cged using modified polystyrene fom nd cloth-net cup cges nd individul Lygus dults were relesed in the pproprite cges nd llowed to feed for 48 hours. Control cges received zero insect ugmenttion. After 48 hours, relesed Lygus ugs were killed in ll cges nd 50% of the infested olls from ech oll ge cohort were retrieved nd processed in the lortory to evlute internl nd externl Lygus dmge lesions, oll weight, dimeter, nd oll hrdness. The remining 50% of the infested olls were kept for hrvest to determine yield nd lint qulity Study. The study ws deployed in split-plot rndomized lock design with three replictions (locks) to quntify the dmge potentil of Lygus dults nd lte-instr nymphs with respect to cotton oll development stge. The study consisted of three Lygus infesttion levels (one dult Lygus feeding for 48 hours, one lte-instr nymph feeding for 48 hours, nd zero ugs per oll) s min plot fctors nd ten cotton oll ge cohorts (every-other-dy cging of white flowers, lso referred to s 1-dy old olls, from Dy 1 to Dy 20) s suplot fctors. Thus, there were 90 experimentl units. Ech experimentl unit hd four individully cged olls s susmples, thus, this study comprised of totl of 360 individully cged cotton olls (three locks x three Lygus infesttion levels x ten oll ge cohorts x four susmples). Cotton field ws divided into three locks. Ech lock consisted of 10 cotton rows, representing 10 oll ge cohorts. Every two dys for period of 20 consecutive dys (4 August to 22 August), one cotton row ( min plot) ws rndomly selected nd fifty rndomly selected new, white flowers were individully tgged, yielding 10 cotton oll ge cohorts. On Dy 20 (23 August), ll 360 olls were cged using modified polystyrene fom nd cloth-net cup cges nd individul Lygus dults or nymphs were relesed in the pproprite cges nd llowed to feed for 48 hours. Control cges received zero insect ugmenttion. After 48 hours, relesed Lygus ugs were killed in ll cges nd 25% of the infested olls from ech oll ge cohort were retrieved nd processed in the lortory to evlute internl nd externl Lygus dmge lesions, oll weight, dimeter, nd oll hrdness. The remining 75% of the infested olls were kept for hrvest to determine yield nd lint qulity. These individul olls were hrvest on Octoer Study. A split-plot rndomized lock field study ws deployed with replictions. The study ws n extensive undertking in which ten cotton oll ge cohorts (tgging of olls everyother-dy from Dy 1 to Dy 20) served s min plot nd three Lygus infesttion levels (I: one Lygus nymph feeding for 72 hours, II: one Lygus dult feeding for 72 hours, nd III: control or zero ugs) within ech oll ge served s suplots. Individully tgged (nd cged on Dy 21) olls served s replicte, thus, this study comprised of totl of 750 individully cged cotton olls (25 replictions x three Lygus infesttion levels x ten oll ge cohorts). To ensure the retention of 750 cged olls fter 20 dys of tgging, we tgged 1000 olls (100 olls per dy). Every two dys for period of 20 consecutive dys (July 27, 29, 31, August 2, 4, 6, 8, 10, 12, nd 14), one cotton row ws consecutively selected nd 100 rndomly selected new, white 27

32 flowers were individully tgged, yielding 10 cotton oll ge cohorts. Cotton olls in the Texs High Plins ccumulte n verge of 20 HU per dy, thus optimlly; the oldest cup-cged oll will (t 20 dys) hve ccumulted 400 HU. On Dy 21 (August 15), ll tgged olls were cged using modified polystyrene fom nd cloth-net cup cges. Individul Lygus dults (n=25 olls per oll-ge cohort) nd nymphs (n=12 olls per oll-ge cohort) were relesed in the pproprite cges nd llowed to feed for 72 hours. Control cges (n=13 olls per oll-ge cohort) received zero insect ugmenttion. After 72 hours, relesed Lygus ugs were killed in ll cges on August 19 nd 3 (control), 4 (nymph-ugmented), nd 6 (dult-ugmented) olls from ech oll ge cohort were retrieved nd processed in the lortory to evlute internl nd externl Lygus dmge lesions. The remining olls were kept for hrvest to determine yield nd lint qulity. These single olls were hrvested on Octoer 9. Figure 1. Deployment of cup-cges to enclose ge-specific olls for Lygus dmge potentil study, Luock, TX, Determintion of Boll Mturtion Profile, Feeding Preference nd Economic Threshold A field study ws conducted to quntify the effect of Lygus density nd infesttion timing on cotton yield nd fier qulity. Cotton plnting nd field mngement opertions were the sme s descried for Estimting Lygus Boll Dmge Potentil section ove. For studies, the experiment ws lid out in split-plot rndomized lock design with three replictions, two min plot fctors (two cotton oll developmentl stges [erly oll development nd lte oll development]), nd four suplot fctors (four levels of Lygus infesttion [control or zero ugs, one ug/plnt, two ugs/plnt, nd four or six ugs/plnt]). There were totl of 24 experimentl units. Ech experimentl unit hd 8 cotton plnts s susmples (3 used for dmge ssessment nd 5 for yield nd qulity ssessment). A totl of 192 whole-plnt sleeve-cged cotton plnts (three locks x two cotton oll stges x four Lygus densities x eight susmples) were used for this study (Fig. 2). The cotton field study site ws closely monitored nd kept virtully rthropod pest-free until cges were deployed on July 24, July 29, nd July 28 in 2012, 2013, nd 2014, respectively. When the cotton plnts reched the trget mturity level (350 HU >60 F fter first flower on August 7, August 13, nd August 17 in 2012, 2013, nd 2014, respectively, nd 550 HU >60 F fter first flower on August 21, August 29, nd August 27 in 2012, 2013, nd 2014, respectively), field-collected Lygus were relesed into the whole-plnt sleeve-cges t the rtes of 0, 1, 2, nd 4 Lygus/plnt in 2012 nd 2013; the infesttion densities were chnged to 0, 2, 4, nd 6 Lygus/plnt in 2014 to increse the dmge intensity. Lygus dults were collected from nery lflf field or from djcent counties nd then cclimtized in the lortory for 48 28

33 hours efore using them for the oll feeding experiment. Cotton plnts were exposed to the Lygus dults for ~7 dys, fter which time, the insects were killed vi pesticide ppliction. Three rndomly selected cotton plnts from ech plot were clipped ner the soil surfce nd rought to the lortory on August 13, August 19, nd August 27 for the 350 HU nd August 29, Septemer 2, nd Septemer 5 for the 550 HU plots in 2012, 2013, nd 2014, respectively. In 2015, the study lyout ws similr to tht for previous yers, ut we evluted three min plot fctors (three cotton oll developmentl stges [erly, mid, nd lte oll development]), nd five suplot fctors (five levels of Lygus infesttion [control or zero ugs, one ug/plnt, two ugs/plnt, four ugs/plnt, nd six ugs/plnt]), replicted four times. Three oll development stges were chrcterized s olls hving ccumulted 200 HU, 350 HU, nd 550 HU, representing erly, mid, nd lte Lygus oll infesttions, respectively. Forty-five plot sections (3-ft row section with >50% of the plnts with the first white flower on the plnt) were mrked on 27 July nd the dily het unit ccumultion (>60 o F) ws clculted to prepre for tretment deployment. Plnt stnd inside ech 3-ft section ws thinned to mintin 6 plnts per section (1 ws used for dmge ssessment nd 5 for yield nd qulity ssessment) on the dy of cge deployment. On 5 August, het unit ccumultions reched c. 200 HU. The experimentl cges were deployed on pre-selected 6-plnt sections nd the density tretments were pplied on this dte. Lygus dults nd nymphs were collected from nery lflf field nd 0, 1, 2, 4, or 6 Lygus per cge. Seprte studies were conducted for Lygus dults nd nymphs. Cges were removed on August 15, one plnt per cge ws removed for dmge ssessment, nd the remining plnts were spryed with n insecticide to kill ugmented Lygus. Lygus feeding on mid- nd lte oll development stges were evluted y relesing the sme Lygus density tretments s descried for erly oll development stge. Lygus density tretments were deployed on August 9 (350 HU) nd 18 (550 HU) nd terminted on August 19 nd 28 for mid nd lte oll development stges, respectively. The cotton crop ws defolited y sprying FOLEX 6EC (12 oz per cre) nd oll opener (Ethephon 6; 32 oz per cre) in tnk mix in , ut the 2015 crop ws terminted vi nturl freezing. After the crop ws redy to hrvest, the remining 5 cged plnts from ech plot, which hd een mintined pest-free, were hrvested mnully to evlute the lint yields nd fier qulity. Hrvested single-plnt smples ( ) or 5-plnt smple per cge (2015) were ginned individully vi tle-top gin nd smples were nlyzed for fier qulity (HVI) prmeters t Cotton Incorported. ANOVA, GLM model vi SAS (2010) ws used to evlute the tretment effects (α=0.1) nd tretment mens were compred y LSMEAN procedure. Figure 2. Field deployment of single-plnt cges ( ) nd multi-plnt cges (2015) for Lygus threshold study, Luock. 29

34 Results nd Discussion Boll Development vs. Lygus Dmge Potentil The Luock re cotton crop during the August 1-20 period in 2012 received 24 HU per dy nd olls developed rpidly. The dimeter of the cotton olls grew t n verge rte of 1.2 mm per dy nd gined n verge of 1.4 grms of weight per dy. As the olls mtured nd ecme lrger, the crpel wlls ecme hrder s evidenced y the pressure required to puncture the crpel wll, incresing t rte of l per squre foot per dy (Fig. 3). The 2013 nd 2014 oll development ptterns were similr to tht for When forced to feed on single oll, ech Lygus dult inflicted, verged cross ll oll ge cohorts, externl lesions per oll in 48 hours. Numerous externl lesions were found in ll olls, irrespective of their ge. It indictes tht in no-choice feeding sitution Lygus cn cuse externl feeding injury to ll olls, ut the ctul numer of dmged seeds ws significntly reduced s olls ecme older, lrger nd tougher to puncture. When olls reched n ge of 16 dys (2012) or 13 dys (2013), Lygus cused very little seed dmge (<2 seeds per oll) tht did not result in significnt lint yield reductions (Figs. 4-5). We were unle to derive this reltionship for 2014 dt due to field mngement filure prior to hrvest. When cotton olls received >350 HU fter first flower, they were sfe from Lygus-induced fier yield loss. Cotton olls were oserved to e sfe from Lygus dmge when the olls: 1) exceeded >28 mm in dimeter, 2) weighed >14 g, or 3) crpel wll puncture force exceeded 0.7 l per squre foot (Figs. 3-5). Boll dmge potentil significntly incresed s olls mture from Dy 1 to Dy 7, demonstrting tht the 1-wk old olls re the most sensitive to Lygus injury. The dmge potentil egins to decrese fter 7 dys, ut olls re still susceptile to Lygus injury for out nother 5-6 dys. Considering yer-to-yer vritions, it ppers tht the mturing olls re no longer susceptile to Lygus injury two weeks fter white flower (Figs. 4 nd 5). In multi-plnt cge study (2015), externl feeding mrk (sunken lesions on the externl surfce of the oll) numers were considerly higher in erly seson olls compred to tht in lte seson. Numer of externl lesions per oll incresed with incresed Lygus density, which is especilly pronounced during the erly seson period (Fig. 6). Four Lygus per plnt cused significntly higher externl lesions compred to the control nd the 1 nd 2 Lygus per plnt tretments; however, incresing the density to six Lygus per plnt did not increse the externl feeding injury mrks (Fig. 6). Our previous study suggested tht the survivorship of the fieldcollected nd cge-relesed Lygus dults in the Texs High Plins is out 20-25%. Therefore, our highest ctul density ws set round ugs per plnt. Internl injury followed the similr trend s for externl lesions, with n incresed numer of internl injury wrts s Lygus densities incresed. Regrdless of the crop s phenologicl stges, Lygus cused internl injuries to the olls compred to tht in control cges. However, density-dependent reltionship etween Lygus density nd internl oll dmge ws more evident in lte seson (Fig. 7). 30

35 Het units >60 o F y = 24.17x R² = 0.99 Boll dimeter (mm) y = 1.18x R² = Boll ge (dys) Boll ge (dys) Boll weight (g) y = 1.36x R² = 0.87 Crpel wll hrdness (l/ft 2 ) y = 0.018x R² = Boll ge (dys) Boll ge (dys) Figure 3. Cotton oll ge reltionships s ssocited to het unit ccumultions, oll size, oll weight, nd crpel wll hrdness, Luock, Texs, Externl lesions per oll Boll ge (dys) Figure 4. Cotton oll injury (externl lesions nd dmged seeds) t vrious oll ges following 48-h feeding of single Lygus dult, Luock, TX, Dmged seed per oll Boll ge (dys) 31

36 Figure 5. Single-oll lint yield (grms per oll) following 48 hours of feeding y single Lygus dult versus uninfested oll t oll ges rnging from Dy 1 to Dy 19, Luock, TX, * indictes tht the Lygus-infested olls resulted in significntly lower yield thn non-infested olls. Figure 6. Cotton oll externl injury (externl lesions) t two phenologicl stges of cotton following 7-dy exposure of vrious densities of Lygus dults in multi-plnt cges, Luock, TX,

37 Figure 7. Cotton oll internl injury (internl wrts) t two phenologicl stges of cotton following 7-dy exposure of vrious densities of Lygus dults in multi-plnt cges, Luock, TX, Fruiting Profile At 350 HU fter first flower, n verge of 57% fruit retention ws oserved, ut fruit retention ws decresed to 37% when cotton reched 550 HU fter first flower. Cotton plnts t 350 HU were oserved to hve 84% olls, 14% squres nd 2% flowers, while t 550 HU, the cotton plnts hd 99% olls, 1% squres, nd no flowers. Although there were higher percentge of cotton olls on 550 HU plnts, the ctul numer of olls per plnt decresed from n verge of 8.8 olls per plnt t 350 HU to 6.3 olls t 550 HU. Approximtely 28.4% of the olls were nturlly orted from the plnts s they mtured from the 350 HU to 550 HU stge (Fig. 8). Nodl position Nodl position Averge numer of fruit Averge numer of fruit Figure 8. Fruiting profile t 350 (left) nd 550 (right) HU fter first flower, Luock, TX,

38 Most of the olls were from first fruiting positions of the sympodil rnches. At 350 HU, 66%, 24%, 8%, nd 2% olls were from the first, second, third nd fourth sympodil rnch fruiting positions, respectively; while t 550 HU, 81%, 16%, 3%, nd 0% olls were from the first, second, third nd fourth sympodil rnch fruiting positions, respectively (Fig. 9). When the cotton plnts mtured from 350 HU to 550 HU, they dropped ll of the 4 th fruiting position nd most of the 3 rd fruiting position olls. Since 97% of the olls were on first nd second fruiting positions on the cotton plnts t the 550 HU stge, our smpling nd crop protection efforts should e focused on protecting primrily the first nd second position olls t this stge. However, fruiting profiles my vry with cotton cultivr, cotton growing region, nd crop mngement prctices nd input use ptterns. Nodl position 15 1st position 14 2nd position 13 3rd position Averge numer of olls Averge numer of olls Figure 9. Boll distriution on sympodil rnches t 350 (left) nd 550 (right) HU fter first flower, Luock, TX, Boll Mturtion Profile Thirty-two cotton plnts were hrvested (16 plnts ech from 350 HU nd 550 HU plots) from which 643 olls were retrieved. Boll dimeter ws mesured using Vernier cliper nd olls were ctegorized into 6 oll size groups (5-10, 11-15, 16-20, 21-25, nd mm). Our pst reserch indictes >25 mm dimeter sized cotton olls re sfe from Lygus dmge. Plnts t 350 HU hd 47% of the olls sfe from Lygus dmge (lrger thn 25 mm dimeter), wheres fter 2 dditionl weeks, cotton in the sme field hd 70% of the olls sfe from Lygus dmge. When the cotton crop mtured from 350 to 550 HU, the proportion of olls vulnerle to Lygus feeding dmge ws reduced from 53% to 30%. Therefore, it is likely tht with similr level of Lygus infesttion, Lygus my cuse greter mount of cotton yield loss when infesting midseson crop (350 HU) compred to tht for lte seson infesttion (550 HU). For our 2012 cotton crop, within-plnt cotton oll mturtion profile shows tht olls distriuted from the 5 th to 14 th nodes (Fig. 8). At the 350 HU stge, the top 4 olls (from th node) were <25 mm dimeter size nd were vulnerle to Lygus dmge if ugs were present (dt not Nodl position 34

39 shown). When the cotton reched 550 HU, only the top 3 olls (nodes 11-13) were <25 mm dimeter size nd therefore vulnerle to Lygus dmge, if present. Bolls from the 5 th to 9 th nodes were lrger nd less vulnerle to Lygus feeding dmge. There ws very strong positive reltionship etween oll size (dimeter) nd the hrdness of the oll crpel wll. As we move from the top to ottom nodes of cotton plnt, s expected, we found lrger olls with hrder crpel wlls (Fig. 10). The verticl oll profile suggests tht cotton growers or crop consultnts need to focus their Lygus dmge evlutions primrily during the HU, nd mostly on the top 3-4 olls, since they re the most vulnerle to Lygus feeding injury. The 2013 dt lso showed similr trends in terms of within-plnt oll mturtion distriution Nodl position (ottom to top) HU Dimeter 350 HU Dimeter Nodl position (ottom to top) HU Boll hrdiness 350 HU Boll hrdiness Boll dimeter (mm) Boll hrdness (l/sq ft) Figure 10. First position oll size profiles of 350 nd 550 HU cotton fter first flower, Luock, TX, Lygus Boll Feeding Preference nd Boll Dmge In the whole-plnt cging study, Lygus externl feeding lesions were found in olls of ll sizes, indicting Lygus ttempted to feed on cotton olls irrespective of oll size. Nevertheless, successful punctures nd the resulting internl wrts were limited to the olls <35 mm in dimeter. A significntly higher proportion of olls hd internl wrts (>20% of olls) for <30 mm olls, indicting tht in n open-choice sitution, Lygus preferred to feed on olls tht were <30 mm in dimeter (Fig. 11). Cotton plnts t the 350 HU hd 90% of the olls mesuring <30 mm in dimeter, wheres plnts t the 550 HU hd 78% of the olls t <30 mm dimeter (Fig. 35

40 11). The no-choice cup-cge study showed olls tht re >25 mm dimeter were sfe from Lygus dmge, wheres in the open-choice whole-plnt cging study, Lygus preferred to feed on olls up to 30 mm in dimeter. This slight discrepncy might e due to differences in cotton oll development inside cup-cges versus whole-plnt cges, or due to differences in Lygus ehvior in the presence of different oll size options nd continments. Evlution of internl lesions nd internl wrts suggests there is not significnt reltionship etween externl Lygus feeding lesions nd ctul seed dmge due to Lygus feeding (Fig. 12), ut there were strong reltionships etween the numer of internl wrts nd numer of Lygus dmged seed. It clerly indictes tht estimting Lygus dmge y using externl lesions cn e misleding; therefore, it is est to use the numer of internl wrts to estimte the degree of Lygus crop dmge. Percent infested olls Boll dimeter rnge (mm) Figure 11. Boll feeding preference of Lygus in whole-plnt cges sed upon the proportion of externl nd internl oll dmge. Luock County, TX, Numer of dmged seeds y = 0.19x R² = Externl lesions y = 1.01x R² = Figure 12. Reltionships etween the numer of dmged seeds per oll nd the numer of externl lesions or internl wrts, Luock, TX, Numer of dmged seeds Internl wrts 36

41 Yield Loss In generl, s expected, Lygus ugmenttion reduced the lint yield compred to tht in uninfested control cges (Figs ). However, the dmging effect of Lygus ws more pronounced during mid-seson (350 HU from first flower) compred to tht in lte seson (550 HU from first flower) for ll four yers of the study. In 2012, rtificil ugmenttion of 2-4 Lygus ugs per plnt t 350 HU fter first flower significntly reduced the cotton lint yield, ut the sme level of Lygus infesttion t 550 HU did not result in significnt lint yield reduction compred with tht in uninfested control plnts (Fig. 13). Augmenttion of 1, 2, nd 4 Lygus ugs per plnt t 350 HU fter first flower reduced the cotton lint yield y 116, 425, nd 580 l/cre, respectively, wheres the yield reductions for the sme Lygus densities were 125, 149, nd 185 l/cre during the lte seson (550 HU from first flower). These dt suggest tht the mturing olls re much more tolernt to Lygus injury when the plnt ttins 550 HU from first flower. It is lso possile tht Lygus ugs my choose to feed on superfluous olls or squres nd the yield contriuting fruits my not e significntly impcted y such lte infesttions. Becuse potentil yield loss risks due to certin Lygus density infesttions vry with oll mturtion profile, the Lygus mngement economic threshold should e optimized for dynmic ET to ccommodte for within-plnt fruit mturity profiles. In 2013, cotton lint yields in mid-seson plots (cges) were much lower thn in 2012, ut the ugmenttion of 1, 2, nd 4 Lygus ugs per plnt reduced the cotton lint yield y 157, 106, nd 281 l/cre, respectively (Fig. 14). While these lint yield reduction vlues were not sttisticlly significnt, owing to greter vrition in dt, the trend ws convincingly supportive of cler influence of Lygus ugmenttion on yield reduction nd the dt trend ws similr to tht in Overll, lint yield ws higher in lte-seson test plnts compred to tht in mid-seson test plnts, ut the ugmenttion of 1 Lygus per plnt did not result in significnt yield reduction, wheres 2 nd 4 Lygus per plnt reduced 143 nd 159 l/cre, respectively (Fig. 14). In 2014, ugmenttion of 2, 4, nd 6 Lygus per plnt t 350 HU fter first flower reduced the cotton lint yield y 407, 406, nd 516 l/cre, respectively, wheres the yield reductions for the sme Lygus densities were 282, 295, nd 415 l/cre during the lte seson (550 HU from first flower) (Fig. 15). Overll yield in 2014 ws higher thn in 2012 nd 2013, ut the dmge inflicted y 2 nd 4 Lygus per plnt on mid-seson cotton ws comprle to tht for 2012, wheres the dmge inflicted in lte seson cotton ws higher in 2014 compred to tht in 2012 or In 2015, overll, lint decresed for ech successive phenologicl stges of cotton due to n rtifct of experimentl logistics (Fig. 16). Ech cge contined out 12 plnts nd plnts were thinned to 6 per cges t the time of insect relese. As result, the erly seson test hd significntly more time to compenste for thinned plnt densities compred to when we thinned the densities in successive phenologicl stges. Within ech phenologicl stge, higher Lygus densities significntly reduced the lint yield compred to tht in control cges. Erly seson crop compensted for oll injury nd the yield in 0, 1, nd 2 Lygus-ugmented cges were similr. During mid-seson, Lygus infesttions reduced yield significntly for ll densities, indicting the greter vulnerility of the mid-seson crop to Lygus injury in the Texs High Plins. In lte 37

42 seson, low densities of Lygus (1 or 2 Lygus/plnt) overcompensted the yield s Lygus likely fed on young, non-hrvestle fruits which provided n opportunity for hrvestle olls to mture (Fig. 16). The seed yield followed the sme pttern s oserved for lint yield (Fig. 17). Lygus-induced lint yield reduction for given Lygus density ws lower for lte seson compred to tht for mid-seson infesttions in ll four yers of the study (Figs ). Averged over four yers, on 1,200 l/cre crop, rtificil ugmenttion of 1, 2, 4, nd 6 Lygus per plnt t 350 HU fter first flower reduced the cotton lint yield y 199, 271, 407, nd 433 l/cre, respectively, wheres the yield reduction vlues for the sme Lygus densities were 52, 142, 229, nd 269 l/cre during the lte seson (550 HU from first flower). Thus, the Lygus yield reduction potentil significntly decresed when cotton mtured from 350 HU to 550 HU. These dt clerly suggest tht the mturing olls re more tolernt to Lygus injury when the plnt ttins 550 HU from first flower. It is lso possile tht Lygus ugs my choose to feed on superfluous olls or squres nd the yield contriuting fruits my not e significntly impcted y such lte infesttions. Becuse potentil yield loss risks due to certin Lygus density infesttions vry with oll mturtion profile, the Lygus mngement economic threshold should e optimized for dynmic ET to ccommodte for within-plnt fruit mturity profiles. Regression nlysis of the four-yer dt suggests tht Lygus dults could inflict mximum lint losses of 127 nd 71 l/cre, respectively, for mid- versus lte seson infesttions of per unit (1 dult) Lygus per plnt (Fig. 18). Bsed on this study, Lygus mngement options for Texs High Plins cotton fter the initition of first flower re recommended s follows: 1) creful monitoring of cotton crop nd djcent hitts for Lygus undnce nd movement ehvior nd voidnce of insecticide tretment for Lygus in cotton prior to 200 HU from first flower, 2) 2-4 Lygus per 6 row-ft for mid-seson cotton, nd 3) 4-6 Lygus per 6 row-ft for lte seson cotton. Figure 13. Influence of vrying levels of Lygus infesttions on lint yields t two crop phenologicl stges, s mesured y het-unit ccumultion eyond first white flower, Luock County, TX,

43 Figure 14. Influence of vrying levels of Lygus infesttions on lint yields t two crop phenologicl stges, s mesured y het-unit ccumultion eyond first white flower, Luock County, TX, Figure 15. Influence of vrying levels of Lygus infesttions on lint yields t two crop phenologicl stges, s mesured y het-unit ccumultion eyond first white flower, Luock County, TX,

44 Figure 16. Cotton lint yield following 7-dy exposure of vrious densities of Lygus dults in multi-plnt cges t three cotton phenologicl stges, Luock, TX, Figure 17. Cotton seed yield following 7-dy exposure of vrious densities of Lygus dults in multi-plnt cges t three cotton phenologicl stges, Luock, TX,

45 Figure 18. Regression nlyses on verge of four yers of Lygus single, whole-plnt cge study dt ( ) nd 2015 dt on multi-plnt cge study showing the reltionship etween the mount of lint yield reduction nd Lygus density ugmenttion per plnt. Mid-seson infesttion, y= x (R 2 = 0.94); Lte seson infesttion, y= x (R 2 =0.99); x=numer of dult Lygus ugs ugmented per plnt, y=lint yield (l/cre). Summry There ws significnt chnge in oll composition (oll profile) etween the cotton plnts t 350 nd 550 HU from first flower. Despite sutle vrition etween no-choice (cup-cged single oll feeding) versus choice (single-plnt or multi-plnt cges with ccess to ll oll types for feeding) situtions, it ppered tht olls were reltively sfe t mm dimeter size or 350 HU, which ws pproximtely equivlent to 2-wk old olls. While yer-to-yer vrition exists nd the vrition in oll susceptiility is expected cross cropping system mngement (irrigtion, plnting dte, fertility, etc.), mturing olls should generlly e sfe from Lygus injury two weeks fter white flower, especilly for Lygus dults. Lygus-induced lint yield reduction for given Lygus density ws lower for lte seson compred to tht for mid-seson infesttions in ll four yers of the study. Erly seson (200 HU) dt were collected only during the 2015 seson, so there were insufficient dt to mke specific recommendtions for erly seson mngement. Averged over four yers, on 1,200 l/cre crop, rtificil ugmenttion of 1, 2, 4, nd 6 Lygus per plnt t 350 HU fter first flower reduced the cotton lint yield y 199, 271, 407, nd 433 l/cre, respectively, wheres the yield reduction vlues for the sme Lygus densities were 52, 142, 229, nd 269 l/cre during the lte seson (550 HU from first flower). Thus, the Lygus yield reduction potentil significntly decresed when cotton mtured from 350 HU to 550 HU. These dt clerly suggest tht the mturing olls re more tolernt to Lygus injury when the plnt ttins 550 HU from first flower. It is lso possile tht Lygus ugs my choose to feed on superfluous olls or squres nd the yield contriuting fruits my not e significntly impcted y such lte infesttions. Becuse potentil yield loss risks due to certin 41

46 Lygus density infesttions vry with oll mturtion profile, the Lygus mngement economic threshold should e optimized for dynmic ET to ccommodte for within-plnt fruit mturity profiles. Regression nlysis of our current four-yer dt suggests tht Lygus dults could inflict mximum lint losses of 127 nd 71 l/cre, respectively, for mid- versus lte seson infesttions of per unit (1 dult) Lygus per plnt (Fig. 18). Although this study used up to 6 Lygus per plnt to chrcterize the feeding ehvior nd to estlish the tretment thresholds, our previous studies suggest tht the survivorship of the field-collected nd cge-relesed Lygus dults in the Texs High Plins is out 20-25%. Therefore, our highest ctul density ws set round ugs per plnt. Bsed on this study, Lygus mngement options for Texs High Plins cotton fter the initition of first flower re recommended s follows: 1) creful monitoring of cotton crop nd djcent hitts for Lygus undnce nd movement ehvior nd voidnce of insecticide tretment for Lygus in cotton prior to 200 HU from first flower, 2) 2-4 Lygus per 6 row-ft for mid-seson cotton, nd 3) 4-6 Lygus per 6 row-ft for lte seson cotton. Acknowledgements We thnk our funding gencies including Cotton Incorported Texs Stte Support Committee nd Plins Cotton Growers, Inc. The uthors lso re indeted to Dr. R.B. Shresth, Richrd Normn, nd severl undergrdute students, whose technicl ssistnce in the field ws invlule. References Ju, Jr. G. L., nd L. A. Crruth Growth nd yield of cged cotton plnts infested with nymphs nd dults of Lygus hesperus. J. Econ. Entomol. 64: Oosterhuis, D. M., nd M. Kim Structurl nd iochemicl chnges in the oll wll in support of the NAWF het units rule, pp In Proceedings, Beltwide Cotton Conferences, Ntionl Cotton Council, Memphis, TN. Prjulee, M. N., R. B. Shresth, A. K. Brmn, nd S. C. Crroll Ecologiclly intensive pest mngement in cotton groecosystems: Lygus hesperus s model system. Egyptin Journl of Agriculturl Reserch 86: Prjulee, M. N., M. B. Adhikri, D. L. Kerns, R. B., Shresth, nd S. C. Crroll Insecticide termintion rule for western trnished plnt ug in the Texs High Plins, pp In Proceedings, Beltwide Cotton Conferences, Ntionl Cotton Council, Memphis, TN. Willims, M. R Cotton insect losses-2012, pp In Proceedings, Beltwide Cotton Conf., Ntionl Cotton Council, Memphis, TN. 42

47 PROJECT FINAL REPORT Cotton Incorported Core Progrm Project Numer: Chrcteriztion of Cotton Crop Response to Thrips Injury for Improved Thrips Mngement in Texs High Plins Cotton Sumitted y: Megh N. Prjulee Texs A&M AgriLife Reserch 1102 Est FM 1294 Luock, TX (806) Coopertors: Adul Hkeem, Postdoctorl Reserch Associte Sen Coyle, Technicin Stnley C. Crroll, Reserch Scientist 43

48 Chrcteriztion of Cotton Crop Response to Thrips Injury for Improved Thrips Mngement in Texs High Plins Cotton Megh N. Prjulee Texs A&M AgriLife Reserch nd Extension Center, Luock, Texs PROJECT SUMMARY The western flower thrips, Frnkliniell occidentlis Pergnde, is serious pest on seedling cotton in the Texs High Plins nd other regions of the U.S. cottonelt. Thrips re n erly seson pest which cn cuse severe dmge to seedling cotton. First three weeks of seedling stge is importnt ecuse thrips cn cuse significnt dmge during this period when plnts re 1-3 true-lef stge. Hevy infesttions cn cuse leves to shrivel, reduction in lef chlorophyll content nd lef re, nd ultimtely significnt yield reduction. The mnipultion of thrips popultions in cotton field setting is very chllenging nd mintining selected thrips densities on cotton seedlings in n open field condition re unmngele. Nevertheless, it is essentil to use field cges nd confine known numer of thrips per cged plnts to otin desired thrips density. Specific ojectives of this study were to: 1) evlute cotton vrietl response to nturl coloniztion of thrips in open field studies, 2) greenhouse evlution of cotton vrietl response to thrips ugmenttion, nd 3) design field cge prototype to determine the cotton crop dmge potentil of the western flower thrips for developing n economic threshold. The ultimte gol of the reserch project ws to develop new economic thresholds for thrips sed upon plnt response chrcteristics, vlidting or revising the current Texs High Plins thrips tretment threshold recommendtions, nd precisely chrcterizing the cotton crop response to vrious levels of thrips injury t different cotton seedling ges. In the greenhouse study, 0, 0.5, 1 nd 2 thrips per plnt were relesed t 1- to 2- true-lef stge. Twenty-two dys following the relese, seedlings were hrvested, wshed nd thrips counted. Significntly higher thrips densities were oserved from tretments where 1 or 2 thrips were relesed per seedling compred to 0.5 nd control. Visul rnking vlues of plnts from thrips densities 0 nd 0.5 were significntly superior (i.e., less visul dmge) compred to tht from thrips densities 1 nd 2. Similr densities were chieved in field cges vi thrips relese in NoThrips cges to compenste for 80% field mortlity. Significnt numers of thrips were recovered from ll thrips-ugmented tretments, with lowest numers recovered from control plnts. Lef re ws significntly higher in uninfested control compred to those in thripsugmented tretments. Seedling helth, mesured y visul rnking, declined progressively with incresed thrips densities. Thrips 0.5 thrips per plnt or greter significntly reduced plnt vigor. Thrips densities of 0.5, 1, nd 2 per plnt t erly seedling stge ll reduced lint yield significntly compred to tht in uninfested control plots. Similr densities were chieved in field cges vi thrips relese in No-Thrips cges to compenste for 80% field mortlity. Thrips densities of 0.5, 1, nd 2 per plnt t erly seedling stge ll reduced lint yield significntly compred to tht in uninfested control plots. 44

49 Introduction Thrips re economiclly importnt pests in Texs cotton. Thrips cn e found in cotton throughout the growing seson, ut cotton is most vulnerle to thrips dmge for the first thirty dys following plnting nd cotyledon emergence. In the U.S., thrips infested cumultive re equling 8.9 million cres in 2012 while thrips infested 3.8 million cres in Texs which cused loss of pproximtely 9,000 les in Texs (Willims 2013). Excessive feeding of thrips leds to the rowning of leves on the edges, development of silvery color, or curling upwrd from the edges (Fig. 1). Western flower thrips, flower thrips, soyen thrips, onion thrips, nd tocco thrips re five common thrips species found in U.S. cotton (Cook et l. 2011). Aleldño et l. (2008) hve reported nine species of thrips from Texs cotton. Western flower thrips [Frnkliniell occidentlis (Pergnde)] is key pest in Texs cotton (Greenerg et l. 2009) nd cuses severe dmge to cotton seedlings in infested fields, which re generlly vulnerle to thrips dmge up to the 4-5 true lef stge (Cook et l. 2011). Thrips cuse lef re destruction, delyed mturity, retrded plnt growth nd loss of picl dominnce (Reed et l. 2001, Sdrs nd Wilson 1998, Hrp nd Turner 1976). Previous thrips surveys reveled t lest eight thrips species in Texs cotton, ut Frnkliniell occidentlis (western flower thrips) nd Thrips tci (onion thrips) re the most common species, comprising more thn 75% of the thrips found in Texs cotton. The vrious thrips species in Texs, eing difficult to identify, hve typiclly een mnged s single complex, with single pproch eing rodly pplied. Differentil dmge potentil nd pesticide susceptiility mong these species remin unexmined, ut with the recent ldicr (Temik ) discontinution, their exmintion my ecome criticl. Lcking thrips-tolernt cotton cultivrs, cotton growers primrily use insecticides to control thrips. While severl seed tretment options re ville, soil-pplied ldicr hd een the most relile nd common method used for cotton seedling thrips control. With the discontinution of ldicr, cotton growers will need lterntive thrips mngement techniques, especilly in the Texs High Plins. Idelly, cotton growers should e empowered with the cpility to estimte the dily cost of delying folir insecticide pplictions for controlling thrips, further empowering them to finely djust nd chieve their cceptle, sustinle economic injury level for mximum enefits nd minimum costs. Proposed project outputs include informtion such s the specific reltionship etween the degree of thrips injury to cotton seedlings nd the resulting plnt response in terms of finl yield nd fier qulity, the specific cotton growth stge most vulnerle to thrips infesttion, n ccurte economic threshold for inititing thrips mngement ctions, nd the effect of infesttion durtion on cotton development nd lint yield, ll of which would e vlule to empower growers with such cpility, given EPA-mndted ldicr discontinution. Folir insecticide pplictions re likely to replce ldicr, nd re likely to increse in numer. Given such n increse, nd since informtion regrding specific thrips species, their dmge potentil, nd how cotton responds is unville, the risk of excessive or indequte insecticide use is likely to increse s well. Further, while Texs A&M AgriLife Extension currently provides generl thrips mngement thresholds, such rodly-pplicle thresholds re insufficient to ddress specific thrips species, different injury levels, infesttion durtion, nd their effects on the cotton crop growth response nd finl yield potentil. Therefore, the gol of this project is to develop pplicle informtion which will empower producers to optimize the timing nd extent of mngement ctions to mitigte thrips dmge while protecting the groecosystem, mximizing yields, nd minimizing production costs. In ddition to enefitting 45

50 producers, the outcome of this study will id crop consultnts nd county IPM gents in mking recommendtions to improve thrips mngement in Texs High Plins cotton. The mnipultion of thrips popultions in cotton field setting is very chllenging nd mintining selected thrips densities on cotton seedlings in n open field condition re unmngele. Nevertheless, we must use field cges nd confine known numer of thrips per cged plnt to get desired thrips density. Specific ojectives of the second yer of this study were to: 1) evlute cotton vrietl response to nturl coloniztion of thrips in open field studies, 2) greenhouse evlution of cotton vrietl response to thrips ugmenttion, nd 3) design field cge prototype to determine the cotton crop dmge potentil of the western flower thrips for developing economic thresholds. The ultimte gol of the reserch project is to develop new economic thresholds for thrips sed upon plnt response chrcteristics, vlidting or revising the current Texs High Plins thrips tretment threshold recommendtions, nd precisely chrcterizing the cotton crop response to vrious levels of thrips injury t different cotton seedling ges. A B C Figure 1. A) Adult western flower thrips, Frnkliniell occidentlis, B) Severe dmge cused y F. occidentlis to seedling cotton, C) Stunted cotton seedlings due to thrips injury. Mterils nd Methods Ojective 1. Cotton cultivr response to nturl coloniztion of thrips in the field This study ws conducted t the Texs A&M AgriLife Reserch frm locted ner Luock, Texs. The study ws deployed in rndomized lock design with four replictions nd six cultivr tretments. Experimentl plots were eight 40-inch rows wide x 90 ft long nd 5 ft lleys seprted the plots. Six cotton cultivrs (SSG-HQ-212-CT, DP 353, FM 1740 B2F, T CT 1205, T CT 1206, nd PHY 367 WRF) were plnted on My 9 (2013) nd June 3 (2014). Ech 8-row plot ws further divided to two 4-row plots nd ech of the two 4-row plots ws rndomly ssigned to control or spryed tretment. Thus, the entire study consisted of 48 experimentl units (six cultivrs x two tretments x four replictions) Study. Cotton germintion ws delyed due to cooler soil tempertures, ut the plnt emergence ws stisfctory in most plots. Poor crop stnd on some experimentl plots my e ttriuted to vritions in cultivr seedling vigor rther thn to the soil conditions. Plnt stnd counts were performed on My 23 nd June 3 y counting ll plnts in 3 row-ft per row in ll 48 plots. Thrips densities were monitored in ll 48 plots using ten-plnt thrips wshing technique. Thrips smpling dtes were My 23 (pre-tretment), My 25, June 3, June 10, nd June 17. An insecticide (Orthene 3.0 oz/cre) ws spryed in ll 24 spryed tretment plots fter 46

51 ech thrips smpling event on My 24, My 30, June 11, nd June 18, nd the entire test (ll 48 plots) ws spryed with this insecticide on June 26. Insecticide tretment ppliction ws skipped fter the thrips smpling event on June 3 due to spry logistic issues, ut the residul insecticides from previous week s ppliction kept the thrips popultions suppressed until the insecticide ppliction on June 11. Plnt response to thrips injury ws monitored y mesuring plnt height, shoot length, root length, totl lef re, nd totl dry iomss of cotton seedlings from ech plot on June 24. A 10-ft section ws mrked on ech of the two center rows within ech plot nd the flowering profile ws monitored 2-3 times per week. This type of phenologicl monitoring egn prior to the initition of flowering nd continued until crop cut-out. Flowering profiles were monitored on July 10, 12, 16, 19, 22, 24, 26, 30, August 13, nd 30. The two 10-ft sections from the middle two rows (20 totl row-ft/plot) tht were designted for plnt fruiting response were hrvested to estimte the cotton lint nd seed yields from ech experimentl plot. Plnt response to thrips injury ws monitored y mesuring shoot length, root length, shoot iomss, root iomss, totl lef re, nd totl dry iomss of cotton seedlings from ech plot. The study re received pproximtely 3.0 inches of rin on July which provided much needed rek from n extended drought. Nevertheless, the test plots received full complement of irrigtion nd the test hd not een exposed to wter-stress sitution. Frequent cultivtions kept the weeds under control s well. The crop received hrvest-id chemicls on Octoer 9 nd the crop ws hrvested on Novemer 4, followed y smple ginning on Novemer Study. The study site received frequent rins tht cooled the soil temperture. Thus, the erly crop growth ws extremely slow. Plnt stnd counts were performed on 13 June y counting ll plnts in 3 row-ft on ech of the four rows in ll 48 plots. Thrips densities were monitored in ll 48 plots using five-plnt thrips wshing technique in ech plot. Thrips smpling dtes were June 19 nd 25, nd July 8. An insecticide 3 oz. per cre) ws spryed in ll 24 spryed tretment plots on June 23, ut there were no visile thrips in susequent smpling events to wrrnt dditionl spry pplictions. Hrsh wether conditions followed y some unexplined hericide drift injury on most of the conventionl (non Roundup Redy) cotton lines in the region round the third week of June nd first week of July prevented the test crop from chieving norml growth. Test plots were rnked using 1-10 scle (1 eing ded nd 10 eing helthy plnts) on 16 July for crop vigor. Cultivr PHY 367 WRF nd FM 1740 B2F scored 8 nd 7.5, respectively, while SSG-HQ-212 CT scored the lowest t Overll, the stnd counts were poor. Monsnto representtives visited the test site to scertin the hericide injury. Similr symptoms hd een oserved in other regions of the Texs High Plins on cotton cultivrs tht did not possess the Roundup Redy technology. The crop vigor did not improve during much of the growing seson. No further pesticide ws pplied ecuse of low thrips presence nd stunted growth of the crop. Nevertheless, the crop ws hrvested nd ginned Study. A field study ws deployed in rndomized lock design with four replictions nd five cultivr tretments. Experimentl plots were eight 30-inch rows wide x 50-ft long nd 5-ft lleys seprted the plots. Five cotton cultivrs (FM 958, , , , AllTex Atls) were plnted on June 4, 2015 t the Texs A&M AgriLife Reserch frm in Hlfwy, TX. Ech 8-row plot ws further divided to two 4-row plots nd ech of the two 4-row plots ws rndomly ssigned to control or spryed tretment. Thus, the entire study consisted of 40 experimentl units (five cultivrs x two insecticide tretments x four replictions). 47

52 Thrips densities were monitored in ll 40 plots using five-plnt thrips wshing technique. Thrips smpling dtes were June 12, 24, nd July 3. An orgniclly pproved insecticide (Entrust 2 oz/cre) ws spryed in ll 20 spryed tretment plots on June 15, 29, nd July 3. Frequent rin events prevented from thrips coloniztion in the study site, which rendered the study filure. Ojective 2. Cotton cultivr response to different thrips densities in the greenhouse 2013 Study. A greenhouse study ws conducted to determine the mximum potentil effect of different densities of thrips on seedling cotton. Six cotton vrieties ( CT-1206, CT-1205, PHY367 WRF, SSG HQ212 NCT, FM 1740 B2RF nd ST 5458B2RF) were plnted in 16-oz Styrofom cups on Octoer 8, At the ottom of the Styrofom cups, 1-3 smll holes were mde to llow for wter dringe from the potting soil. The study ws deployed in completely rndomized lock design with four replictions, six cultivrs, nd four thrips densities. Ech experimentl unit contined 6 plnts. Thrips were field-collected from cotton nd rered on green ens in the lortory. Immture thrips were trnsported to the greenhouse in continers with green ens. A rush ws used to dislodge thrips from the green ens onto the cotton seedlings. Every effort ws mde to relese only immture thrips to void unintentionl movement of thrips etween tretments. Thrips densities relesed included: no thrips (control), ½ thrips per plnt (e.g., one thrips per two plnts), one thrips per plnt, nd two thrips per plnt t the 1- to 2-true lef stge. An utomtic sprinkler system ws progrmmed to wter the plnts three times per week for 8 minutes/cycle. In ddition, supplementl wter ws mnully pplied s needed. The greenhouse mient ir tempertures were recorded using smll ibutton dtlogger (Mxim Integrted, Sn Jose, CA). Visul lef tissue dmge rnkings of ll plnts were recorded prior to clipping. Rnking ws sed on scle of 1-10 (1 = helthy plnts nd no dmge symptoms nd 10 = plnts killed y thrips). Chlorophyll redings were lso recorded using chlorophyll meter to determine if tretments (thrips densities) nd/or tested cotton vrieties hd n impct on chlorophyll levels. Lef re from ech tretment ws lso recorded using lef re meter to test whether lef surfce res were influenced y the vrious thrips level tretments. Thrips were llowed to feed nd reproduce for three weeks (the durtion tht is equivlent to the western flower thrips lifecycle) efore plnts were clipped ner the soil surfce nd plced into dentured ethyl lcohol. Lter, the dult nd juvenile thrips were quntified vi plnt wshing technique s follows: All six plnts per unit were plced on fine sieve nd rinsed in wter until ll thrips could e dislodged from the leves nd terminls onto very fine sieve (No. 150), nd then thrips were wshed in slt solution. Snd nd hevy mterils were removed from the ottom opening of the seprtory funnel nd thrips were plced on filter pper. A vcuum system ws used to remove extr wter. Adults nd juveniles were counted using microscope t 10X or higher mgnifiction. Numers of thrips from ech tretment nd vriety were recorded nd used in the nlysis. Anlysis of vrince ws used to determine the effect of thrips densities on cultivrs Study. The identicl greenhouse study of 2013 ws repeted in Six cotton cultivrs were plnted in 16-oz Styrofom cups. The study ws deployed in complete rndomized lock design with four replictions. Ech experimentl unit contined six plnts. Thrips were rered on green ens purchsed from locl grocery stores. Four densities of thrips relesed onto 48

53 seedling cotton included: no thrips (control), ½ thrips per plnt (one thrips per two plnts), one thrips per plnt, nd two thrips per plnt t 1- to 2-true lef stge. On the control plnts, Orthene 97UP ws pplied twice weekly. Twenty-two dys following the thrips releses, the plnts were clipped ner the soil surfce nd stored in 90% ethyl lcohol for the thrips wshing procedure. Prior to clipping the plnts, visul lef dmge rnkings were conducted which ws sed on 1-10 scle (1 = norml helthy plnts nd 10 = plnts killed y thrips). Chlorophyll redings were recorded using chlorophyll meter nd lef re from ech tretment ws recorded using lef re meter. Adult nd juvenile thrips were quntified vi wshing technique nd counted using microscope t 10X or higher mgnifiction. Anlysis of vrince ws conducted to test if thrips densities hd n effect on tested vriles. Ojective 3. Developing thrips economic threshold for seedling cotton 2014 Study. Density-dependent threshold studies were conducted in seedling cotton t the Texs A&M AgriLife Reserch frm ner Luock. Rectngulr wooden-frme cges [98 cm (L) x 30 cm (W) x 44 cm (H)] with No-Thrips screen were constructed nd deployed in the field, with ech cge enclosing 8-13 cotton seedlings (Fig. 2). Silicone culk ws used to ttch no-thrips screen to the wooden frme. A sheet metl flshing (1-1½-in width) ws ttched t the ottom of the cge to restrict thrips movement from the ottom of the cge. A temperture sensor ws kept inside the cge to record the internl cge tempertures (Fig. 2). Freshly collected dult thrips, primrily western flower thrips, were relesed t vrious densities to generte dmge grdient cross density tretments. After the thrips were relesed nd the plnts cged, thrips were llowed to feed for 5-10 dys nd then the cges were removed. Two plnts from ech cge were removed nd wshed to retrieve thrips to estimte the thrips survivl. Within 24 h of cge removl, thrips ugmented plots were spryed with Orthene 97UP to kill ll remining thrips. Remining plnts were kept insect-free throughout the reminder of the growing seson; these plnts were hrvested nd ginned for lint yield estimtion. Three seprte studies were conducted to cpture within-seson vrition in seedling response to vrious thrips density tretments. Experimentl protocols were identicl in ll three tests. Figure 2. Wooden-frmed No-Thrips cges instlled in the field nd relese of thrips densities for threshold study (left); thrips infested cotton seedlings (right). 49

54 Test I. Cultivr ST 5458 B2RF, without the seed tretment for thrips mngement, ws plnted on My 15, Field cges were deployed nd six thrips density tretments were relesed onto plnts on June 6 when the cotton seedlings were t the 1-2 true-lef stge. Six density tretments included 0, 1, 2, 4, 6, nd 10 thrips per plnt, replicted five times (30 totl cges). Within four dys of thrips relese, the test site received 2.5 of rinfll. Therefore, we llowed the thrips exposure to continue for out 10 dys efore removing the cges. Two plnts from ech cge were hrvested nd wshed to retrieve thrips. After removl of cges, thrips ugmented rows were spryed with Orthene 97UP. Test II. Only 100 m from the Test I site, Test II ws conducted on the sme cotton cultivr using the sme cges. This cotton cultivr ST 5458 B2RF ws plnted on June 3 nd the test ws deployed on June 18 t the 1-2 true-lef stge. Thrips densities included 0, 1, 2, 4, 6, nd 10 thrips per plnt plus n uncged control. Cges were removed on June 23 nd two plnts from ech cge were clipped t the se nd wshed to retrieve thrips. After removl of cges, thrips ugmented rows were spryed with Orthene 97UP. Test III. Immeditely fter Test II ws terminted, Test III ws deployed in the sme experimentl field only 50 feet wy from Test II using the sme cges. Thrips cges were deployed nd thrips were relesed on 25 June. Becuse the seedlings were t the 4-5 true-lef stge, thrips relese densities were incresed. Tretments included 0, 2, 4, 10, 20 nd 30 thrips per plnt. Cges were removed on July 1, removed two plnts per cge to retrieve thrips vi plnt wshing, nd spryed Orthene 97UP to kill ugmented thrips on remining plnts. Following removl of the cges, ll plots were regulrly monitored such tht the study site could remin reltively pest-free for the reminder of the seson. Plnt-mpping dt were collected nd the cotton lint from the plnts ws hrvested to quntify the crop response to vrious levels of thrips infesttions. Density-dependent threshold studies were conducted in seedling cotton ner Luock. Rectngulr wooden-frme cges [98 cm (L) x 30 cm (W) x 44 cm (H)] with No-Thrips screen were constructed nd deployed in the field tht enclosed 8 seedlings per cge (Fig. 2). Silicon ws used to ttch no-thrips screen to the wooden frme. A thin metl flshing (1-1½-in width) ws ttched t the ottom of the cge to restrict thrips movement from the ottom of the cge. A temperture sensor ws kept inside the cge to record the tempertures Study. The study design ws ner-identicl to the 2014 study, except for thrips density djustment in Three seprte studies were conducted to cpture within-seson vrition in seedling response to vrious density tretments. Nevertheless, the experimentl protocols were identicl in ll three tests. Test I. Cultivr ST 4946 GLB2 ws plnted on My 27, Field cges were deployed nd thrips density tretments pplied on June 6 when cotton seedlings were t the cotyledon stge. Six density tretments included 0, 1, 2, 4, nd 6 thrips per plnt, replicted six times (totl 30 cges). Thrips were llowed to feed for 5 dys nd cges were removed on June 12, nd then thrips relese rows were treted with Orthene 97UP. Test II. Only 100 m from Test I experimentl site, Test II ws conducted on the sme cotton cultivr. This cotton ws plnted on My 27 nd test ws deployed on June 12 when seedlings were out 2 true-lef stge. Thrips density tretments included 0, 1, 2, 4, nd 6 thrips per plnt. Cges were removed on June 19. After removl of thrips cges, thrips ugmented rows were spryed with insecticide Orthene 97UP. Test III. Immeditely fter Test II ws terminted, Test III ws deployed in the sme 50

55 Numer of thrips per five plnts experimentl field only short distnce wy from Test II. Thrips cges were deployed nd thrips relesed on June 19. Becuse the seedlings were t out 4-5 true-lef stge, density tretments were 0, 5, 10, 15, 20, nd 25 thrips per plnt. Cges were removed on June 26. From ll three tests, two plnts per cge were removed nd wshed for thrips density estimtion. These test plots were monitored throughout the growing seson for ny other pests nd mintined the test res reltively pest free for the reminder of the seson. Test plots were hrvested the following week to quntify the crop response to vrious levels of thrips infesttions. In ddition to field-cge studies, n ttempt ws mde to compre thrips cge studies with openfield releses. Three sets of cge studies (noted ove) were mtched with identicl uncged tests next to ech study simultneously. One week fter ech relese, Orthene 97UP ws spryed to keep plnts free from thrips. Hrvested cotton ws ginned nd lint nd seed yields were recorded. Results nd Discussion Ojective 1. Cotton cultivr response to nturl coloniztion of thrips in the field 2013 Study. Visul thrips counts did not significntly vry etween tretments or cultivrs. Stnd counts etween tretments were lso non-significnt; however, plnt counts were significntly higher in CT1205, CT1206, DP353 nd PHY376 compred to FM1740 nd SSGHQ. Cultivr DP353 nd PHY367 hd significntly more thrips in control plots thn spryed plots (Fig. 3). However, drstic vrietl difference in plnt growth nd yield msked the sutle difference in thrips tolernce cross these tested vrieties. No significnt thrips popultion densities or lint yield differences were found etween the insecticide-treted nd untreted control portions of the other four cultivrs. Cultivr DP353 hd the longest flowering period nd pek flowering occurred lter in the seson compred with other cultivrs exmined (Fig. 4). In oth treted nd control plots, the highest numer of white flowers were oserved in PHY367 on July 30 (Fig. 4) nd pek flowering continued from mid-july through August. Severl significnt differences were oserved etween plnt iomss nd cultivr tretments (P<0.1) in control nd spryed plots (Tles 1 nd 2); however, interctions etween insecticide nd cultivr tretments were non-significnt. Significntly lower lint yield in untreted control plots (P<0.1) ws oserved etween spryed nd control plots in DP353 nd PHY367 which might e due to presence of significntly more thrips in control plots thn insecticide-spryed plots in these two cultivrs (Fig. 5). Significnt differences in seed yield ws oserved etween spryed nd control plots in DP353 only, wheres no significnt differences in seed yield were oserved etween spryed nd control plots in other cultivrs (Fig. 6). 8 Treted Untreted CT1205 CT1206 DP353 FM1740 PHY367 SSGHQ Figure 3. Thrips densities recovered using whole-plnt wshing procedure,

56 Figure 4. Flowering profile of cotton cultivrs in untreted control (upper pnel) nd insecticide spryed plots (lower pnel), Tle 1. Vrietl vrition in selected plnt prmeters oserved in control plots, Luock, TX, Vrieties/Lines Plnt Prmeters CT1205 CT1206 DP353 PHY367 FM1740 SSGHQ Shoot length (cm) Root length (cm) Shoot iomss (g) Root iomss (g) c 1.20c 1.49c 0.93c Lef iomss (g) Lef re (cm 2 ) Lef chlorophyll

57 Lint yield per cre (l) Tle 2. Vrietl vrition in selected plnt prmeters oserved in spryed plots, Luock, TX, Vrieties/Lines Plnt Prmeters CT1205 CT1206 DP353 PHY367 FM1740 SSGHQ Shoot length (cm) Root length (cm) Shoot iomss (g) Root iomss (g) Lef iomss (g) Lef re (cm 2 ) Lef chlorophyll Control Spryed CT1205 CT1206 DP353 FM1740 PHY367 SSGHQ Figure 5. Lint yield (l per cre) cross tested cultivrs nd reeding lines, Seed yield per cre (l) Control Spryed CT1205 CT1206 DP353 FM1740 PHY367 SSGHQ Cultivrs Figure 6. Seed yield (l per cre) cross tested cultivrs nd reeding lines, During this study, we oserved tht field coloniztion of thrips ws low during the study period, vried with cultivrs, with DP353 ttrcting the most dult thrips nd lowest densities oserved in FM1740 nd SSGHQ (Fig. 3). 53

58 2014 Study. Becuse the plnt growth ws compromised (see Mteril nd Method section ove) for this study for much of the erly growing seson, thrips coloniztion did not occur. As result, the study ws reduced to simple gronomic comprison of tested cultivrs nd germplsms. The test plots were hrvested on Decemer 15, 2014 nd ginned on Jnury 12, Lint yield vried significntly mong tested cultivrs, ut the seed yield did not vry mong the cultivrs (Fig. 7). Weight (g) B AB AB AB A PHY 367 DP 353 FM 1740 CT 1205 CT 1206 SSG-HQ AB A A A A A A Lint Weight Seed Weight Figure 7. Lint nd seed yield (l per cre) cross tested cultivrs nd reeding lines, Ojective 2. Cotton cultivr response to different thrips densities in the greenhouse In 2013, severl fctors were significnt etween relesed thrips densities nd thrips numers recovered. A significnt numer of thrips (dults + immtures) were recovered etween densities 0, 0.5, 1 nd 2 (Fig. 8). For oth dult nd immture thrips numers, thrips relese density 0 hd the lowest numers of thrips retrieved compred to the thrips ugmented tretments, indicting tht the thrips movement cross tretments ws miniml. Totl thrips retrieved were the highest t 1 thrips per plnt tretment, followed y 2 thrips per plnt, 0.5 thrips per plnt, nd the lowest numer in uninfested tretment, ll significntly different from ech other (Fig. 8). Totl thrips/6 plnts D C Thrips density relesed per plnt Figure 8. Recovery of totl thrips (dult nd immture) from seedling cotton using plnt wshing technique following greenhouse study, Adult thrips numers retrieved fter three weeks of study were highest in 0.5 nd 1 density tretments, followed y 2 thrips per plnt, nd the lowest numers in uninfested tretment (Fig. A B 54

59 9). Immture thrips densities incresed to 157 nd 104 per 6-plnt tretments t 1 nd 2 thrips per plnt densities, respectively, wheres 0.5 thrips per plnt resulted in 32 thrips per 6-plnt (Fig. 10). No significnt differences were found etween cultivrs on recovered totl thrips (dults + immtures), immtures only or dults only. In 2014, totl thrips were significntly higher in the 2 thrips per plnt relese tretment, followed y 1 nd 0.5 thrips per plnt tretments, nd n insignificnt numer in the uninfested tretment (Fig. 11). Adults/6 plnts A AB BC C Thrips density relesed per plnt Figure 9. Recovery of dult thrips (22 dys fter initil thrips releses) from seedling cotton using plnting wshing technique in greenhouse study, Immtures/6 plnts A B C C Thrips density relesed per plnt Figure 10. Recovery of immture thrips from seedling cotton using wshing technique in greenhouse study,

60 Numer of thrips recovered per tretment 70 A B B 10 0 C Thrips density relesed per plnt Figure 11. Recovery of totl thrips (dult nd immture) from seedling cotton using plnt wshing technique following greenhouse study, Lef re. Lef surfce re mesurements were significnt etween thrips density 0 nd oth 0.5 nd 2 tretments; however, no significnt differences in lef re were recorded etween thrips relese densities of 0 nd 1 per plnt; nd densities 1 nd 2 (Fig. 12). Additionlly, no significnt differences were found in lef re reduced y thrips mong the cultivrs tested. There ws cler indiction tht thrips infesttions, regrdless of the densities, tended to reduce the lef surfce re in seedling cotton. Visul rnking. Significnt differences were oserved in visul rnking of the cotton seedlings etween thrips densities relesed (P = ); however, no significnt differences (P>0.05) were recorded in visul rnking etween cultivrs. Visul injury rnking ws significntly lower (significntly less injury) in thrips densities 0 nd 0.5 compred with tht in thrips densities 1 nd 2; however, no significnt differences (P>0.05) were recorded in visul rnking etween thrips densities 1 nd 2 (Fig. 13). It is noteworthy tht 0.5 thrips per plnt exerted significntly higher injury, sed on visul rnking, compred with tht in no-thrips control plnts. Chlorophyll redings. In 2014, no significnt differences were oserved in chlorophyll redings of the indictor lef on seedlings etween thrips densities relesed (P>0.05) ut vrious significnt differences (P<0.05) were recorded in chlorophyll redings etween cultivrs tested (Fig. 14). Cultivr CT-1206 showed the highest chlorophyll redings, which were significntly different from ST 5458B2RF, PHY 367WRF nd HQ212NCT. No significnt differences (P>0.05) in chlorophyll levels were recorded mong cultivrs CT-1205, CT-1206 nd 1740B2RF. Also, no significnt differences (P>0.05) in chlorophyll levels were recorded mong ST 5458B2RF, PHY 367WRF nd HQ212NCT. Chlorophyll redings were not consistent etween 2013 nd 2014 cross cultivrs tested (Fig. 14). 56

61 400 A 350 Men lef re (cm 2 ) B AB B Thrips density relesed per plnt Figure 12. Effect of western flower thrips injury on lef surfce re of the cotton seedlings t vrious thrips densities in greenhouse study, A A 2 B 1 C Thrips density relesed per plnt Figure 13. Effect of western flower thrips injury on visul lef dmge rnking of the cotton seedlings t vrious thrips densities in greenhouse study,

62 Figure 14. Effect of western flower thrips injury on chlorophyll redings of the cotton seedlings of selected cultivrs in greenhouse study, 2013 (left) nd 2014 (right). Ojective 3. Determine the cotton crop dmge potentil of the western flower thrips for developing economic thresholds 2014 Study. No-thrips cges ppered to contin thrips in the field cges etter thn ny of the other field cge mterils (frics) tht we hve used in previous studies. Different mterils nd designs were used in the pst, including 1) trnsprent plstic cup cge, 2) wire mesh sleeve cge, 3) opque plstic cylinder, 4) trnsprent plstic jr without ventiltion, nd 5) trnsprent plstic jr with ventiltion (Fig. 15). None of these methods were suitle for thrips studies in the field ecuse of the excessive temperture uildup inside the cges, plus mteril of the screen ws unle to contin the thrips. However, the No-Thrips cge design provided stisfctory performnce. 6 Figure 15. Cge types evluted previously: 1) trnsprent plstic cup cge, 2) wire mesh sleeve cge, 3) opque plstic cylinder, 4) trnsprent plstic jr without ventiltion, nd 5) trnsprent plstic jr with ventiltion. Despite our preliminry study showing stisfctory thrips retention in the No-Thrips cge, 5- dy post-relese thrips retrievl ws much lower thn expected in ll three studies. We speculted tht frequent rin nd cool/wet wether might hve ttriuted to this lower thrips 58

63 retrievl from the cges. It ws lso suspected tht there might hve een greter mortlity once they were relesed into the cges. We do not elieve tht the lrge numer of thrips escped from the cges, ut smll numer of escpes is lwys possiility. Despite the low rte of retrievl, it ppers tht the thrips feeding hd exerted some effect on the plnts, resulting in reduced yield. On the first test, ll five thrips ugmented tretments hd lower verge lint yields (749 l/cre in 6 thrips/cge tretment to 964 l/cre in 4 thrips/cge tretment) compred to tht in control cges (1145 l/cre), lthough the vlues were not sttisticlly significnt owing to lrge vrince in the dt (Fig. 16). Test II lso suggested tht thrips feeding occurred, resulting in lower plnt height nd smller min-stem dimeter in ll thrips ugmented tretments compred to tht in control cges (Fig. 17). Nevertheless, the thrips feeding, if ny, during the seedling stge in this study did not significntly impct lint yields (Fig. 17). Test III ws conducted when plnts were ner the end of the thrips tolernt stge: 5-6 true-lef stge with good crop helth. Therefore, significnt yield-reducing effect of thrips ugmenttion ws not expected. Nevertheless, thrips ugmented tretment cges hd numericlly lower yield compred to tht in control cges (Fig. 18). Figure 16. Numer of thrips recovered t 5-dy post-relese into field cges nd lint yield from cotton infested with vrying densities of thrips in No-Thrips cges during the 1-2 true-lef stge, Luock, Texs, 2014 (Study I). 59

64 Figure 17. Numer of totl thrips (immtures plus dults) recovered t 5-dy post-relese into the field cges, plnt height, stem dimeter, nd lint yield from cotton infested with vrying densities of thrips in No-Thrips cges during the 1-2 true-lef stge, Luock, Texs, 2014 (Study II). Figure 18. Numer of thrips (immture, dult, nd totl) recovered t 5-dy post relese into the field cges nd lint yield from cotton infested with vrying densities of thrips in No-Thrips cges during the 5-6 true-lef stge, Luock, Texs, 2014 (Study III). 60

65 2015 Study. As noted erlier, the 2015 growing seson ws mrked y hevy nd frequent rinfll events, especilly during the seedling period when cotton ws most prone to thrips coloniztion nd vulnerle to thrips injury. As result, retrievl of thrips 7 dys post-relese, s proxy for thrips coloniztion, ws very low. Thrips releses t 5-6 true-lef stge, which is generlly considered s the cotton stge tht is no longer susceptile to thrips injury, ppered to colonize thrips on plnts, ut these numers were insignificntly low for this crop stge (Fig. 19). Seedling growth nd the totl folige surfce re incresed significntly when crop stge dvnced from 0-1 to 1-3 nd then from 1-3 to 5-6 true-lef stge (Fig. 20), rendering the crop less susceptile to thrips injury s crop stge dvnced. Becuse thrips densities were low nd there were no mesurle symptoms of thrips feeding, cotton lint yield did not generlly vry cross thrips density tretments, regrdless of the seedling stge tht the infesttions were ugmented. Nevertheless, cotyledon stge did pper to show some significnt yield reduction or trend towrd lint yield penlty in thrips ugmented tretments, except the highest density tretment hd no yield difference with tht in control plots (Fig. 21). The two-yer multi-plnt cge study suggested tht thrips density-dependent threshold studies cn e conducted in the Texs High Plins using the No-Thrips cges. However, severl considertions my e necessry to ccomplish the stted ojectives of developing tretment thresholds sed on such dt. First, 2-3 more yers of density-dependent dt need to e collected to estlish thrips feeding potentil nd plnt response to thrips feeding. Second, fctors responsile for thrips mortlity in cges need to e exmined more thoroughly, stgespecific thrips feeding potentil need to e chrcterized to ccount for thrips ge structure in the popultion. 61

66 Figure 19. Numer of thrips retrieved from cotton seedlings 7-dy post-relese into No-Thrips field cges t three seedling stges, Luock, Texs,

67 Figure 20. Lef re mesurements of seedling cotton t three different seedling stges (<1, 1-3, nd 5-6 true-lef stge), Luock, TX, Figure 21. Effect of vrious densities of thrips releses during three different seedling stges (<1, 1-3, nd 5-6 true-lef stge) on cotton lint yield, Luock, TX,

68 This four-yer project imed to chrcterize the thrips feeding ehvior nd estlish thrips density-dependent dmge reltionship of seedling cotton. The project invested the first two yers to devise thrips field reserch techniques vi exmining severl field cge options to effectively enclose thrips in the field. We re firly confident in our multi-plnt field cge with NoThrips screen mteril for thrips studies in the field. However, the hrsh environmentl conditions in the Texs High Plins region during the erly cotton growth stge, chrcterized y cool wether nd high wind speeds ssocited with sndstorms, prevented this project from chieving the type of dt tht were envisioned. Nevertheless, the 2013 nd 2014 dt from the greenhouse study clerly showed the importnce of thrips mngement in erly seedling stge (Fig. 22), ut the field vlidtion of the greenhouse study ws dversely influenced y hrsh wether conditions. The 2014 field cge study resulted in resonle reltionship etween field-ugmented thrips densities nd lint yield (Fig. 23). However, field ugmented thrips densities filed to estlish thrips on the plnt nd did not result in mesurle injuries to cotton seedlings in Figure 22. Thrips densities retrieved, effect of thrips on seedling growth (lef re), nd visul rnking of the cotton seedlings following thrips infesttion in the greenhouse, , Luock, TX. 64

69 Figure 23. Field vlidtion of the greenhouse study on thrips density ugmenttions nd resulting lint yield reduction, 2014, Luock, TX. Acknowledgement We thnk Cotton Incorported Core Progrm nd Plins Cotton Growers, Inc. Plins Cotton Improvement Progrm for funding. The uthors lso re indeted to Dr. R.B. Shresth, Richrd Normn, nd severl undergrdute students, whose technicl ssistnce in the field ws invlule. References Aleldño,W. A., J. E. Slosser, nd M. N., Prjulee Identifiction of thrips species on cotton on the Texs Rolling Plins. Southwest. Entomol. 33: Cook, D., A. Herert, D. S. Akin, nd J. Reed Biology, crop injury, nd mngement of thrips (Thysnopter: Thripide) infesting cotton seedlings in the United Sttes, J. Integ. Pest Mngement 2: 1-9. Greenerg, S. M., T. X. Liu, nd J. J. Admczyk Thrips (Thysnopter: Thripide) on cotton in the Lower Rio Grnde Vlley of Texs: Species composition, sesonl undnce, dmge, nd control. Southwest. Entomol. 34: Hrp, S. J., nd V. V. Turner Effects of thrips on cotton development in the Texs Blcklnds. Southwest. Entomol. 1: Reed, J., E. Burris, C. Allen, R. Bgwell, D. Cook, B. Freemn, G. Herzog, nd R. Leonrd Thrips (Thysnopter: Thripide) A multi-stte survey: Summry of oservtions for Arknss, Alm, Georgi, Louisin, Mississippi nd Tennessee, pp In Miss. Stte Exp. Stn. Reserch Report 22. Sdrs, V. O., nd L.J. Wilson Recovery of cotton crops fter erly seson dmge y thrips. Crop Sci. 38: Willims, M R Cotton Insect losses-2012, pp In Proceedings, Beltwide Cotton Conf., Ntionl Cotton, Sn Antonio, TX. 65

70 ANNUAL REPORT 2015 Cotton Incorported Texs Stte Support Committee Progrm Project Numer: TX Thrips Mngement in Texs High Plins Cotton Sumitted y: Megh N. Prjulee Texs A&M AgriLife Reserch 1102 Est FM 1294 Luock, TX (806) Coopertors: Adul Hkeem, Postdoctorl Reserch Associte Sen Coyle, Technicin Stnley C. Crroll, Reserch Scientist 66

71 Thrips Mngement in Texs High Plins Cotton Megh N. Prjulee Texs A&M AgriLife Reserch nd Extension Center, Luock PROJECT SUMMARY Thrips re the top-rnked economic insect pests in Texs High Plins cotton. Thrips cn e found in cotton throughout the crop seson, ut cotton is most vulnerle to thrips dmge within the first 30 dys following seedling emergence. Lcking thrips-resistnt cotton cultivrs leves no option for cotton growers ut to primrily use insecticides for thrips mngement. While severl seed tretment options re ville, soil-pplied ldicr hd een the most relile nd common method used for cotton seedling thrips control until the discontinution of ldicr in Folir-pplied insecticides such s spinosds, orgnophosphtes, nd neonicotinoids re the ovious lterntives, ut since these insecticides my negtively impct the groecosystem vi long-term excessive use, their use must e optimized for effectiveness ginst thrips nd miniml ecologicl impcts. Ojectives of this project were to: 1) evlute the folir insecticide ppliction frequency in mnging thrips in seedling cotton, nd 2) evlute the efficcy, residul performnce, nd economic competitiveness of selected products in thrips mngement. The experiment ws conducted t three Texs loctions (Hle County, Swisher County, nd Wilrger County) to represent cotton fields surrounded y vrile vegettion/crop complexes nd thrips popultion pressure in cotton. Thrips popultions sujected to vrious folir insecticide tretment regimes nd thresholds were monitored on cotton cultivr FM 4946GLB2. Insecticide tretments included: 1) untreted check, 2) one folir ppliction t cotyledon stge (100% seedling emergence), 3) folir pplictions t 100% seedling emergence nd 1-2 true lef stge, 4) folir pplictions t 100% seedling emergence, 1-2 true lef stge, nd 3-4 true lef stge, 5) folir pplictions t 1-2 true lef stge nd 3-4 true lef stge, 6) folir tretments sed on the current ction threshold (1 thrips per true lef), nd 7) folir tretments sed on 50% of the current ction threshold. Orthene 97UP t rte of 3.0 oz/cre ws used for ll folir pplictions. Seed tretment (thimethoxm [Avict ], imidcloprid [Aeris ]) nd folir (Orthene, Bidrin, Vydte ) insecticide tretments were evluted for their efficcy nd cost effectiveness in mnging thrips popultions in cotton reltive to n untreted control. The 2015 growing seson ws mrked y cool nd wet spring, frequent rin events during erly growing seson, dry mid-summer, nd wrm fll. Thrips were unle to colonize in ny of our test sites due to frequent rin events. Overll, Hlfwy (Hle Co.) site hd higher thrips undnce thn t Chillicothe (Wilrger Co.) site, ut the densities were fr elow economic threshold level of 1 thrips per lef. Thrips egn to colonize t the seed tretment nd folir insecticide study site ner Hlfwy y the first smpling dte, ut the densities did not sustin due to rin events. On verge, neonicotinoid seed tretments (imidcloprid nd thimethoxm) nd folir insecticide tretments oth significntly reduced thrips popultions compred to tht in untreted control plots; ll five insecticide products provided similr level of thrips popultion suppression. Thrips popultions did not develop t the Chillicothe site. Lint yield did not vry cross tretments t the Chillicothe site where no thrips infesttions occurred. Lint yield ws significntly lower in imidcloprid tretment plots compred to tht in thimethoxm plots t Hlfwy, ut we found no iologicl sis for such difference. Thrips densities were similr nd much elow ET level in ll insecticide tretments, so the yield ws expected to e similr cross ll tretments. 67

72 Introduction Thrips re the top-rnked economic insect pests in Texs High Plins cotton. Thrips cn e found in cotton throughout the growing seson, ut cotton is most vulnerle to thrips dmge within the first 30 dys following seedling emergence. In Texs, n verge of 4.5 million cres of cotton is infested with thrips nnully, nd pproximtely $1.2 million is spent nnully to control thrips in cotton. Thrips re economiclly dmging to Texs cotton, nd results in n verge of 70,000 les lost ech yer, equivlent to $33 million (Willims 2013). Previous thrips surveys reveled t lest eight thrips species in Texs cotton, ut Frnkliniell occidentlis (western flower thrips) nd Thrips tci (onion thrips) re the most common species, comprising more thn 75% of the thrips found in cotton (Aleldno et l. 2008). The vrious thrips species in Texs, eing difficult to identify, hve typiclly een mnged s single complex, with single pproch eing rodly pplied. Differentil dmge potentil nd pesticide susceptiility mong these species remin unexmined. Lcking thrips-resistnt cotton cultivrs leves no option for cotton growers ut to primrily use insecticides for thrips mngement. While severl seed tretment options re ville, soilpplied ldicr (Temik ) hd een the most relile nd common method used for cotton seedling thrips control until the discontinution of ldicr insecticide in Folir-pplied insecticides such s spinosds, orgnophosphtes, nd neonicotinoids re the ovious lterntives, ut since these insecticides my negtively impct the groecosystem vi long-term excessive use, their use must e optimized for effectiveness ginst thrips nd miniml environmentl impcts. Informtion is crucil in chieving such minimiztion, nd n understnding of cotton crop responses to vrious levels of thrips-induced injury throughout seedling development would e vlule for decision-mking relted to implementtion of thrips mngement ctions. Idelly, cotton growers should e empowered with the cpility to estimte the dily cost of delying folir insecticide pplictions for controlling thrips, further empowering them to finely djust nd chieve their cceptle, sustinle economic injury level for mximum enefits nd minimum costs. Specific ojectives of this project were to generte: 1) informtion on commercilly ville, effective nd lterntive chemicl products for thrips mngement, nd 2) informtion on economiclly vile delivery methods for chemicl control (e.g., seed tretment versus folir ppliction) of thrips under vrile growing conditions nd pest pressure. Such informtion is expected to empower Texs High Plins cotton growers to ddress thrips mngement in timely nd cost effective mnner. Mteril nd Methods Ojective 1. Evluting the folir insecticide ppliction frequency in mnging thrips in seedling cotton under vrile levels of pest pressure. The experiment ws conducted t three Texs loctions (Hle County, Swisher County, nd Wilrger County) to represent cotton fields surrounded y vrile vegettion/crop complexes nd thrips popultion pressure in cotton. Thrips popultions sujected to vrious folir insecticide tretment regimes nd thresholds were monitored on cotton cultivr FM 4946GLB2. The individul experimentl plots were 4 rows y 50 feet. Insecticide tretments long with their ssigned tretment numers included: 1) untreted check, 2) one folir ppliction t cotyledon stge (100% seedling emergence), 3) folir pplictions t 100% seedling emergence nd

73 true lef stge, 4) folir pplictions t 100% seedling emergence, 1-2 true lef stge, nd 3-4 true lef stge, 5) folir pplictions t 1-2 true lef stge nd 3-4 true lef stge, 6) folir tretments sed on the current ction threshold (1 thrips per true lef), nd 7) folir tretments sed on 50% of the current ction threshold. Orthene 97UP t rte of 3.0 oz/cre ws used for ll folir pplictions. A plnt wshing technique ws used for collecting nd estimting the thrips densities t ech study loction weekly until the cotton ws no longer considered susceptile to thrips dmge. Five cotton seedlings were selected rndomly from ech plot s smple unit. Plnts were clipped t the se nd plced in.9451-l jr contining pproximtely 100 ml of 70% ethnol. Smples were tken ck to the lortory nd were processed using the wshing technique descried y Burris et l. (1990). The jr ws filled with 500 ml of tp wter nd 10 ml of household lech, nd one drop of liquid detergent ws dded to rek the surfce tension of the wshing solution. The jr ws gitted vigorously for 30 seconds, nd the contents were poured into No. 25 sieve (U.S.A. stndrd testing sieve, Srgent Welch Scientific, Bufflo, NY) on the top of No. 230 sieve, nd the sieves were rinsed to dislodge ny remining thrips. Plnts were discrded nd the sediment ws ckwshed with 70% ethnol into 10 cm dimeter Büchner funnel lined with stndrd drip-coffee filter. The liquid ws then suctioned off using wter fucet vcuum spirtor. The coffee filter with its contents ws exmined under stereomicroscope, nd oth dult nd immture thrips were counted nd recorded seprtely. Study Site I - Wilrger Co. (Chillicothe). Cotton tril ws plnted on June 2, The first thrips smpling ws conducted on June 10, followed y the ppliction of spry tretments on the sme dy. Becuse no thrips were detected on this study site, tretments #6 nd #7 were not triggered. Rin events prevented the smpling crew to ccess this study site t regulr weekly intervl, ut the second smpling ws conducted on June 23, followed y the ppliction of spry tretments on the sme dy. Agin, frequent rin events prevented thrips coloniztion nd no thrips were detected t this site. While this test ws considered filed in regrds to providing relevnt informtion to ddress our reserch gol, the crop ws terminted with hrvest-ids nd hrvested on Novemer 3. Study Site II - Hle Co. (Hlfwy). Cotton tril ws plnted on My 27. The first thrips smpling ws conducted on June 8, followed y the ppliction of spry tretments on the sme dy. Becuse no thrips were detected on this study site, tretments #6 nd #7 were not triggered. Second smpling ws conducted on June 18, followed y the ppliction of the spry tretments. The re-wide frequent rin events prevented the thrips coloniztion t this test site s well. As result, the third smpling on June 26 lso filed to detect ny economiclly relevnt thrips densities to trigger tretments #6 nd #7. While this test ws lso considered filed in terms of providing relevnt informtion to ddress our reserch gol, the crop ws terminted with oll opener (Boll Buster 1 qurt per cre) nd defolint [ET (pyrflufen) 1.25 oz per cre] in tnk mix on Octoer 14 nd the test ws hnd-hrvested on Novemer 8, Study Site III - Swisher Co. Cotton tril ws plnted on June 3. The first thrips smpling ws conducted on June 12, followed y the ppliction of spry tretments on the sme dy. Becuse no thrips were detected on this study site, tretments #6 nd #7 were not triggered. Second smpling ws done on June 24, followed y the ppliction of the spry tretments. The re-wide frequent rin prevented the thrips coloniztion t this site s well. As result, the third smpling on July 3 lso filed to detect ny economiclly relevnt thrips densities to trigger 69

74 tretments #6 nd #7. This test ws completely filed due to recurring wether events. The test ws not hrvested. Ojective 2. Evluting the efficcy, residul performnce, nd economic competitiveness of selected products in thrips mngement Seed tretment (thimethoxm, imidcloprid) nd folir (Orthene, Bidrin, Vydte ) insecticide tretments were evluted for their efficcy nd cost effectiveness in mnging thrips popultions in cotton reltive to n untreted control. The study ws conducted t two different loctions within the Texs High Plins nd one loction in the Rolling Plins to represent cotton fields surrounded y vrile vegettion/crop complexes nd thrips popultion pressure in cotton. Cotton cultivr FM 4946GLB2 ws plnted (Hle Co., My 27; Wilrger Co., June 2; Swisher Co., June 5). Tretment plots with folir pplictions were plnted with the se (miniml seed tretment for wrehouse storge purposes only) seed nd the folir pplictions were sed on Texs A&M AgriLife Extension Service tretment thresholds for thrips. Adult nd immture thrips were smpled y thrips wshing of 5 cotton seedlings, once pre-tretment nd then weekly for three times fter the tretment deployment t Hlfwy (Hle County) loction nd two times t Chillicothe (Wilrger County) loction. Plns were lid-out for plnt dmge rtings nd lef re mesurements, ut no significnt thrips pressure occurred in ny of the three study loctions due to frequent, hevy rin events during the erly growth stge of cotton, except for some low density thrips t the Hlfwy site. Even without the thrips infesttion, we kept the tests t Hlfwy nd Chillicothe loctions for hrvesting to evlute the effect of seed tretments on yield. Test plots were hrvested on Novemer 3 nd 8 in Chillicothe nd Hlfwy, respectively. Hrvested smples were ginned nd lint smples hve een sent to Cotton Incorported for fier nlysis. Results nd Discussion Ojective 1. Evluting the folir insecticide ppliction frequency in mnging thrips in seedling cotton under vrile levels of pest pressure. The 2015 growing seson ws mrked y cool nd wet spring, frequent rin events during the erly cotton growing seson, dry mid-summer, nd wrm nd open fll. Becuse the cotton seedling stge, the susceptile stge for thrips infesttion nd injury, received frequent rin events, thrips were unle to colonize in ny of our test sites. Overll, the Hlfwy site hd higher thrips undnce thn t Chillicothe site, ut the densities were fr elow the current Extension recommended economic threshold level of 1 thrips per lef. At Hlfwy, verge thrips densities rnged from 1 to 3 thrips per 5-seedling smple on June 8, ut the density quickly declined y the next smpling dte. There were no significnt differences in phid densities cross seven folir ppliction tretments (Fig. 1). The Chillicothe study site hd no mesurle thrips densities. Becuse the thrips densities were very low (Hlfwy) to non-existent (Chillicothe), lint yield did not significntly vry with folir ppliction tretments tht were trgeted towrd thrips popultion suppression (Fig. 2). Lint yield ws lower t Hlfwy compred to tht t Chillicothe cross ll tretments. 70

75 Ojective 2. Evluting the efficcy, residul performnce, nd economic competitiveness of selected products in thrips mngement Thrips egn to colonize t the seed tretment nd folir insecticide study site in Hlfwy y the first smpling dte. On June 17 (second smpling dte), thrips undnce incresed nd mrginlly reched the economic threshold of 2 thrips per 2-lef seedling cotton (Fig. 3). However, hevy rin event fter the second smpling dte reduced thrips densities in ll tretment plots to ner zero. Thrips filed to recolonize eyond tht point. On verge, neonicotinoid seed tretments (imidcloprid nd thimethoxm) nd folir insecticide tretments oth significntly reduced thrips popultions compred to tht in untreted control plots (Fig. 3); ll five insecticide products provided similr level of thrips popultion suppression. Insecticide tretments significntly incresed lef re compred with tht in control plots, except for Vydte (Fig. 4). Thrips popultions did not develop t the Chillicothe site. Lint yield did not vry cross tretments t the Chillicothe site where no thrips infesttions occurred. Lint yield ws significntly lower in imidcloprid tretment plots compred to tht in thimethoxm plots t Hlfwy (Fig. 5), ut we found no iologicl sis for such difference. Thrips densities were similr nd much elow ET level in ll insecticide tretments, so the yield ws expected to e similr cross ll tretments. Figure 1. Numer of thrips per 5-plnt smples t two smpling dtes nd sesonl verge thrips densities t Hlfwy s ffected y folir ppliction of Orthene 97UP t different ppliction frequencies in mnging thrips in seedling cotton,

76 Figure 2. Lint yield (l/cre) s influenced y folir pplictions of Orthene 97UP t different ppliction frequencies in mnging thrips in seedling cotton t two loctions. Insecticide tretments numers re s follows: 1) untreted check, 2) one folir ppliction t cotyledon stge (100% seedling emergence), 3) folir pplictions t 100% seedling emergence nd 1-2 true lef stge, 4) folir pplictions t 100% seedling emergence, 1-2 true lef stge, nd 3-4 true lef stge, 5) folir pplictions t 1-2 true lef stge nd 3-4 true lef stge, 6) folir tretments sed on the current ction threshold (1 thrips per true lef), nd 7) folir tretments sed on 50% of the current ction threshold. Hlfwy nd Chillicothe, Figure 3. Numer of thrips per 5-plnt smples t two smpling dtes nd sesonl verge thrips densities t Hlfwy s ffected y seed tretment nd folir pplictions of selected thrips mngement products,

77 Figure 4. Totl lef re per 5-seedling smple s influenced y seed tretments nd folir pplictions of selected thrips mngement products, Hlfwy, TX, Figure 5. Lint yield (l/cre) s influenced y seed tretments (thimethoxm nd imidcloprid) nd folir pplictions (Orthene, Vydte, nd Bidrin ) of selected thrips mngement products t two loctions, References Aleldño, W. A., J. E. Slosser, nd M. N. Prjulee Identifiction of thrips species on cotton in the Texs Rolling Plins. Southwestern Entomologist 33: Burris, E., A. M. Pvloff, B. R. Leonrd, J. B. Grves, nd G. Church Evlution of two procedures for monitoring popultions of erly seson insect pests (Thysnopter: Thripide nd Homopter: Aphidide) in cotton under selected mngement prctices. J. Econ. Entomol. 83: Willims, M R Cotton Insect losses-2012, pp In Proceedings, Beltwide Cotton Conf., Ntionl Cotton, Sn Antonio, TX. 73

78 Sesonl undnce ptterns of ollworm, tocco udworm, nd eet rmyworm moths in the Texs High Plins Stnley C. Crroll nd Megh N. Prjulee Texs A&M AgriLife Reserch nd Extension Center, Luock, Texs INTRODUCTION A long-term study (14 yers nd continuing) study hs een conducted in the southern Texs High Plins (THP) region to investigte the yer-round weekly moth flight ctivity ptterns of cotton ollworm, Helicoverp ze (Boddie), tocco udworm, Heliothis virescens (F.), nd eet rmyworm, Spodopter exigu (Hüner). These three species re importnt cotton pests in the southern Texs High Plins, which is recognized s the most intensive cotton growing region of the world (Fig. 1). In this region, the ollworm is clssified s n importnt economic pest while the tocco udworm nd eet rmyworm re clssified s occsionl pests. The regionl doption of cotton nd corn crop cultivrs incorporting Bt technology hs een instrumentl in reducing the current thret of these lepidoptern pests, yet diminishing underground wter vilility for irrigtion is necessitting lower crop inputs, such s geneticlly modified seed costs, for our incresing drylnd crop production crege. Study Durtion: Mrch 2002 to Present Study Sites: Luock County, Texs MATERIALS & METHODS Pest Species Monitored: Cotton ollworm, tocco udworm, nd eet rmyworm Survey Protocol: Nine pheromone trps [3 lepidoptern species monitored X 3 study sites (replictions)] were plced in Luock County representing the pproximte center of the southern Texs High Plins (Fig. 1). The three sites were selected nd one trp for ech pest species ws plced, then ited nd monitored weekly (growing seson) to twice monthly (non-crop months) throughout the yer. Trp types included: 1) Texs pheromone trp (Fig. 2A, Hrtstck et l. 1979) for ollworms nd tocco udworms, nd 2) Bucket trps (green, Fig. 2B) for eet rmyworms. Pheromone ws secured from single source (Trece, Inc., Adir, OK). Trpping sites were selected nd recorded their GPS coordintes. RESULTS & DISCUSSION Sesonl undnce nd flight ptterns of cotton ollworm, tocco udworm, nd eet rmyworm moths were determined sed upon cptures in pheromone trps monitored ll months of the yer. For ech species, the ongoing 14-yer trpping study hs een su-divided into four successive periods, including: 1) , , , nd , representing oll weevil erdicted nd eginning of Bt cotton doption in THP, low Bt cotton crege (<50%), mjority Bt cotton (70%), nd the current two yers, respectively. 74

79 Figure 1. Texs High Plins pheromone trpping study site, Luock County, TX, Figure 2. S. Crroll services Texs pheromone (TP) trp to monitor ollworm nd tocco udworm moths (A). R. Shresth counts eet rmyworm moths in green ucket trp (B). Figure 3. Numer of ollworm (top-left), tocco udworm (top-right), nd eet rmyworm (ottom-center) moths cptured per week, verged cross four selected 2-4 consecutive-yer groupings spnning the 14-yer study, Luock County, TX,

80 Cotton Bollworm. The cumultive nnul numer of ollworm moths cptured per trp verged 10,618, 7,970, 4,071 nd 5,014 for , , , nd , respectively. The oserved trend suggests decresing, yet high ollworm numers during yers 2002 to 2009, followed y leveling off of numers eginning in 2010 to the present. Fig. 3 (topleft pnel) clerly illustrtes this trend of decresing trp cptures during the first 8 yers, followed y lower, yet firly level ollworm cptures from 2010 to Interestingly, lthough ollworm numers decresed over time, the flight profiles remined quite similr over the four periods. Tocco Budworm. The cumultive nnul numer of tocco udworm moths cptured per trp verged 953, 87, 209 nd 354 for , , , nd , respectively. Higher numers of tocco udworm moths were trpped during the erly period nd then numers decresed nd hve remined firly low in the pst 10 yers with the exception of one pek in erly Septemer (Fig. 3, top-right). Although the numer of trpped udworm moths vried etween the four defined periods, the overll flight ctivity ptterns hd somewht similr profiles with ctivity strting in lte April, pek ctivity during erly August to erly Octoer nd most trp response ending y lte Octoer. Beet Armyworm. The cumultive nnul numer of eet rmyworm moths cptured per trp verged 4,651, 1,790, 4,596, nd 656 for , , , nd , respectively. Although eet rmyworm moths were often cptured during ll months of the yer, they were primrily ctive during the period of mid-mrch to erly Decemer (Fig. 3, ottom-center pnel). Unlike decresing ollworm nd tocco udworm numers since the eginning of the study, no ovious popultion trends re evident. For exmple, high cumultive trpped eet rmyworm numers were oserved during two seprte periods of nd The lowest numers hve een oserved during the current yers. Figure 4. Cotton ollworm (top-left), tocco udworm (top-right), nd eet rmyworm (ottomcenter) moth sesonl flight profiles for: 1) Two study yers with the highest rinfll (2004 & 2015), nd 2) Two lowest rinfll yers (2003 & 2011). Luock County,

81 Influence of nnul rinfll on moth undnce nd flight profiles. Within the 14-yr study period, cumultive nnul rinfll rnged from 5.7-in. to 33.3-in. The two yers with the lowest rinfll were 2003 (8.8-in.) nd 2011 (5.7-in.), while the two highest rinfll yers were 2004 (33.3- in.) nd 2015 (29.5-in.). For ech pest species, the sesonl undnce nd flight profiles re plotted for the two highest nd two lowest rinfll yers (Fig. 4). Cotton Bollworm. The overll timing of the flight profiles were similr etween high nd low rinfll yers, except in regrd to the mgnitude of the pek numers of moths cptured (Fig. 4, topleft pnel). The highest cumultive numer cptured per trp per yer ws 7,254 for the low rinfll yers, while the numers in highest rinfll yers declined y 31.0% to 5,005 moths. Tocco Budworm. Agin, the overll timing of the flight profiles ws similr etween high nd low rinfll yers, ut more udworm moths were cptured during the low rinfll yers (Fig. 4, top-right pnel). The highest cumultive numer cptured per trp per yer ws 533 for the low rinfll yers, while the cumultive numer in the highest rinfll yers declined y 58.5% to 221 moths. Beet Armyworm. During the low rinfll yers, the eet rmyworm flight profile strted erlier nd lso extended lter into the erly winter period s compred to the flight ctive periods oserved during the high rinfll yers (Fig. 4, ottom-center pnel). The highest cumultive numer of eet rmyworm moths cptured per trp per yer ws 3,398 for the low rinfll yers, while the numers in highest rinfll yers declined y 47.8% to 1,773 moths. ACKNOWLEDGMENTS Funding for this study ws provided y Texs A&M AgriLife Reserch Htch Project We cknowledge nd thnk Bill nd Donn Lingren (Trece, Inc.) for their support of this long-term trpping study. REFERENCES Hrtstck, A. W., Jr., J. A. Witz, nd D. R. Buck Moth trps for the tocco udworm. J. Econ. Entomol. 72:

82 Pheromone Trpping of Helicoverp Moth Species in the Texs High Plins: Investigtion of Possile Old World Bollworm Detection Stnley C. Crroll nd Megh N. Prjulee Texs A&M AgriLife Reserch nd Extension Center, Luock, Texs INTRODUCTION An ongoing one-yer study hs een conducted in Luock County to investigte the sesonl moth flight ctivity ptterns of Helicoverp spp. cptured on the following trpping tretments: 1) Two different types of trps, nd 2) Species-specific pheromones otined from severl sources. The investigted insects included Helicoverp ze (Boddie), common key pest of numerous U.S. nd Texs High Plins crops, plus conceivle detection of new invsive old world pest, Helicoverp rmiger (Hüner), commonly referred to s the old world ollworm (OWB). A comprehensive pulished collection of H. rmiger informtion cn e found t the following link: This puliction reports recent OWB detections y scientists in Brzil (2013), Prguy (2013), Argentin (2014), nd most recently from Bolivi, Uruguy, Puerto Rico, nd the U.S. (Florid). The old world ollworm closely resemles the widespred cotton ollworm, H. ze. The dult mle moths of the two species hve slight morphologicl differences tht cn e used y trined individuls to distinguish the two species prt, yet the lrve of these closely relted species cnnot e distinguished prt, except vi DNA nlysis. To complicte mtters relted to species identifiction nd monitoring, the lortory synthesized H. rmiger pheromone incorported into lures produced in order to ttrct old world ollworms to trps is lso very ttrctive to H. ze. For this report, the numers of mle Helicoverp moths cptured per trp per dy re reported, ut genus species complex rekdowns for ech pheromone type or trp type hve not een processed to dte, due primrily to the difficulty nd time requirements of identifiction. We pln to conduct the dissection studies in 2016 in n ttempt to detect ny old world ollworm invsion to Texs. The primry ojectives of the following study were to: 1) Investigte the effectiveness of speciesspecific pheromone lures otined from two vendors, nd 2) Determine the efficiency of two different trp designs in cpturing Helicoverp spp. moths. Ultimte gol of the project is to dissect su-smples of these trpped moths towrds exmining for old world ollworm introduction to Texs. MATERIALS & METHODS Study Durtion: Yer 1 - August 2015 to Novemer 2015 Study Sites: Trgeted Pest Species Monitored: Four sites in Luock County, Texs 1) Cotton ollworm [Helicoverp ze (Boddie)] 2) Old world ollworm [Helicoverp rmiger (Hüner)] Trp Types Tested: 1) Texs trp 2) Bucket trp (green) Pheromone Types nd Sources: 1) Cotton ollworm (H. ze) lures from Trece, Inc. 78

83 Tretments: Trpping Protocol: 2) Old world ollworm (H. rmiger) lures from Trece, Inc. 3) Old world ollworm (H. rmiger) lures from USDA Coopertive Agriculturl Pest Survey (CAPS) Progrm 1) Texs Trp w/ Trece H. rmiger lure 2) Texs Trp w/ Trece H. ze lure 3) Bucket Trp w/ Trece H. ze lure 4) Bucket Trp w/ Trece H. rmiger lure 5) Bucket Trp w/ USDA CAPS H. rmiger lure Five pheromone trps, ech representing one of the study tretments (listed ove), were rndomly ssigned positions t ech of four seprted Luock County sites, ll locted long 21-mile est/west stretch of highwy FM 1294 in northern Luock County. At ech site, the five trps were evenly spced prt y positioning them ner five consecutive electricl utility poles. Plcing the test trps ner utility poles protected the trps from interfering with norml frming opertions in the djcent fields. These study trps were monitored nd the cptured moths counted pproximtely weekly during the study period of August to Novemer. All trps were re-ited with fresh lures pproximtely every two weeks. Exct trpping site loctions were determined vi GPS coordintes. RESULTS & DISCUSSION For ech trp inspection intervl (x-xis), Figure 1 illustrtes the men numer of dult mle moths cptured per trp per dy in trps representing comintions of two trp designs, two species-specific pheromones, nd two sources for the pheromone lures. The chrt clerly shows tht during periods of high Helicoverp flight ctivity, Texs (TP) trps cptured much higher numers of moths s compred to the Bucket trps, while during periods of reduced flight ctivity (e.g., cooler lte-seson period), the differences etween ll five tretments, regrdless of pheromone source or trp design, were reltively smll. Without exception, ucket trps ited with USDA CAPS H. rmiger lures ttrcted fewer moths thn identicl trps ited with Trece H. rmiger lures, which suggests the Trece formulted lure my hve superior properties. During periods of elevted moth flight ctivity, Texs trps ited with Trece H. rmiger pheromone lures tended to ttrct nd cpture more moths thn H. ze ited trps (Figure 2). During inspection intervls with diminished moth flight ctivity, the H. rmiger nd H. ze ited Texs trps oth cptured very few, yet similr numers of moths. Figure 3 illustrtes, s mentioned erlier, tht the green Bucket trps ited with Trece formulted H. rmiger lures (lue line) consistently cptured more moths thn identicl trps ited with the USDA CAPS H. rmiger lures (red line). When one compres the numer of moths cptured on Bucket trps ited with Trece H. rmiger lures versus Bucket trps ited with Trece H. ze lures, the trends re not s consistent s seen with the Texs trps, ut in most cses the H. rmiger ited trps cpture slightly higher numers of moths thn the H. ze ited trps. It should e noted tht most (or ll) of the moths cptured in trps ited with H. rmiger lures re likely H. ze moths; we pln to conduct dissection on su-smples of these collected moths to determine if H. rmiger were cptured in our study. 79

84 Figure 1. Averge numer of Helicoverp spp. mle moths cptured per trp per dy, Luock County, TX, Figure 2. Averge numer of Helicoverp moths cptured per dy per trp, ited with two Trece sourced lures, one for H. rmiger monitoring nd other for H. ze, Luock County, TX, Figure 3. Averge numer of Helicoverp spp. mle moths cptured per dy per trp on green Bucket trps, Luock County, TX,

85 2015 Beltwide Cotton Conferences, Sn Antonio, TX, Jnury 5-7, 2015 EFFICACY OF NEONICOTINOID SEED TREATMENTS ON THRIPS IN COTTON Kte Hrrell Texs A&M University College Sttion, Texs Apur Brmn Texs A&M Agrilife Extension Service Luock, Texs Megh Prjulee Texs A&M Agrilife Reserch Luock, Texs Greg Sword Texs A&M University College Sttion, Texs Gylon Morgn Texs A&M Agrilife Extension College Sttion, Texs Astrct Seed tretments re common nd effective pest control methods in mny crop systems. Cotton seed tretments re often used for control of erly seson pests. A mrket shift in seed tretments to neonicotinoid formultions followed the phsing out of ldicr (Temik ). Imidcloprid nd thimethoxm (Cruiser ) re two commonly used insecticide cotton seed tretments, ut concern lies with the possiility of vrying degrees of efficcy of these seed tretments on the different thrips species. The common thrips species tht infest cotton seedlings re tocco thrips (Frnkliniell fusc), flower thrips (Frnkliniell tritici), western flower thrips (Frnkliniell occidentlis), nd onion thrips (Thrips tci), nd ech of these exhiit different degrees of susceptiility to vrious insecticide formultions. It is necessry for us to evlute the thrips species composition in Texs cotton, s well s the impct of thimethoxm nd imidcloprid seed tretments on those species. The evluted loctions throughout Texs included: Chillicothe, College Sttion, Hlfwy, Kress, Lmes, nd Wll. These re representtive smple res of the High Plins, Rolling Plins, nd Centrl Texs res. Thrips popultions were low in Chillicothe, Lmes nd Wll, ut there were fewer thrips in treted seeds for most smpling dtes in College Sttion, Hlfwy nd Kress. Imidcloprid treted seed resulted in greter yield thn the control in College Sttion, which ws the only hrvested loction with thrips popultions exceeding tretment threshold (one visile thrips per true lef) levels. Greenhouse evlutions of thimethoxm nd imidcloprid seed tretments for western flower thrips provided informtion on mximum potentil efficcy of these products in more controlled environment. Introduction Thrips re n importnt erly seson insect pest on cotton throughout the U.S. cotton elt. In Texs, the thrips complex generlly rnks first in terms of cotton lint yield loss due to insect pests (Willims 2013). Until 2011, thrips were commonly mnged y using in-furrow pplictions of ldicr (Temik ) nd growers chieved stisfctory control. However, the removl of Temik from the mrket due to concern over its possile environmentl impct hs forced cotton producers to resort to other ville insecticide seed tretments. These seed tretment insecticides primrily elong to one insecticide group, the neonicotinoids. Currently, there re two neonicotinoid insecticides ville for use s cotton seed tretments. Although oth insecticides (imidcloprid nd thimethoxm) elong to the sme group, their physicl nd chemicl properties vry, which my result in differences in efficcy of these two products on the trget insect pest (thrips). Therefore, region-specific evlution of different seed tretment products is necessry to determine their effectiveness in mnging thrips popultions in respective regions. Also, product my not e eqully effective on ll the prevlent thrips species impcting cotton cross Texs production regions. For exmple, thrips popultion my e composed of individuls from different species. The common thrips species tht infest cotton seedlings re tocco thrips (Frnkliniell fusc), flower thrips (Frnkliniell tritici), western flower thrips (Frnkliniell occidentlis), nd onion thrips (Thrips tci). Ech of these thrips species could hve vrile levels of tolernce or susceptiility to ech of the ville insecticides. Western flower thrips popultions, for exmple, hve een found to e resistnt to oth orgnophosphtes nd pyrethroids in Austrli (Herron et l. 1996). Similrly, resistnce to pyrethroids within western flower thrips popultions hs een documented from Missouri nd Cliforni (Zho et l. 1995, Immrju et. l. 1995). Historiclly, western flower thrips hve shown to develop resistnce to 81

86 insecticides, s evident from the previous exmples nd numer of other reports from round the world. Therefore, it is possile tht western flower thrips in cotton could develop resistnce to the neonicotinoid seed tretments over time. While western flower thrips re potentil cndidte for developing resistnce to neonicotinoid seed tretments, there re lredy reports of resistnce development to thimethoxm in tocco thrips popultions s documented y severl reserchers from the mid-south of the U.S. (Stewrt 2013). Numer of thrips/10 plnts B B 2-lef stge A B B A AB B 4-lef stge A A ABC B Fig. 1. Numer of thrips recorded on cotton seedlings resulting from two different neonicotinoid insecticide treted seed plntings long with n untreted control; ll three tretments evluted t two plnt growth stges. The thimethoxm (Cruiser ) resistnce in tocco thrips is gret concern for U.S. cotton growers; not only in the mid-south, ut lso in Texs. There re lso some suggestions tht thrips popultions in south Texs, which is dominted y tocco thrips, is less susceptile to Cruiser (thimethoxm) s compred to imidcloprid (Fig. 1). The ove grphs represent the results from tril conducted in Mtgord Co., TX y Dr. Roy Prker nd oserved tht the thimethoxm (Cruiser ) treted cotton plots hd more thrips compred to the seedlings resulting from seed treted with imidcloprid (Gucho Grnde ). It is impertive for us to evlute this product (thimethoxm) more closely in different Texs cotton production regions in order to detect ny possile resistnce development in our thrips popultions. The two ojectives of this study will effectively ddress the possiility of vrying degrees of the neonicotinoid seed tretment efficcy on different species. Specificlly, surveying the thrips species present in Texs fields will provide informtion on the current nd chnging species composition of thrips in Texs cotton, while compring the seed tretments in different loctions will give us direct informtion on the current level of efficcy of the seed tretment insecticides, especilly thimethoxm. The finl gol of this project is to generte informtion regrding thrips popultions in Texs cotton production regions so tht our regionl growers nd consultnts hve useful informtion on wht thrips species re most likely to occur in their fields nd wht ville effective products e used to control those specific thrips species. Mterils nd Methods Greenhouse Trils To evlute the efficcy of thimethoxm nd imidcloprid in controlled environment, we conducted greenhouse study. Two weeks prior to plnting the cotton seeds, we plnted solid trys of whet in order to uild the western flower thrips popultions within the greenhouse. Metro-mix ws used s the potting medium for oth whet nd cotton. Prior experiments in the greenhouse hd highest success with plnting one try of whet for every 2 trys of cotton, so we plnted 48 trys of whet to ensure dequte thrips popultions. We plnted 288 FM 1944 GLB cotton seeds (one seed per experimentl cup), 96 of ech tretment (thimethoxm, imidcloprid, nd control). The seedlings were completely rndomized within trys contining 18 seedlings totl, 6 of ech tretment. Smples of 4 trys were tken t 7 dys fter emergence (DAE), 14 DAE, 21 DAE nd 28 DAE. The smples were tken y cutting the se of the seedlings, nd plcing 6 seedlings of ech tretment in qurt-sized mson jr contining 70% ethnol. Thrips were counted from these smples using the thrips wshing method (Burris et l. 1989). 82

87 Field Trils The field trils consisted of three tretments (thimethoxm, imidcloprid, nd control), with 4 replictions. Plot size ws 4 rows wide y 50 feet long, with 5 feet lleys seprting the plots. Ech tril consisted of 12 plots, rndomized within the repliction (lock). The sites for the field trils were ll locted in Texs, the loctions s follows: Kress (Swisher county), Hlfwy (Hle county), Lmes (Dwson county), Wll (Tom Green county), Chillicothe (Hrdemn county), nd College Sttion (Burleson county). All trils were conducted with sufficient irrigtion. The cotton vriety used ws the sme s we used in the greenhouse, FM 1944 GLB. This cotton vriety ws chosen s it is suited to the regions we chose for tril sites, s well s hving some tolernce to root-knot nemtodes. No nemticide ws pplied to the seeds in order to void ny possile interction with the insecticides we re testing. Plnting dtes were djusted in ech loction ccording to the loction s recommendtion, nd smpling took plce t the cotyledon, 1-2 true-lef nd 3-4 true- lef stges of the plnts. Idelly, smpling ws to tke plce t 7-dy intervls, ut inclement wether nd other mngement logistics forced us to devite from the 7-dy intervls in some cses. During smpling, 10 rndom seedlings from ech plot were plced in qurt-sized mson jr nd tken to the l to e processed using the thrips wshing method (Burris et l. 1989). We recorded the numer of thrips lrve, dults nd the totl numer of thrips from ech plot, nd plced the dults in 70% ethnol for species identifiction lter. Results nd Discussion In the greenhouse, we found no significnt difference etween tretments t ny time intervls, ut over the first 3 weeks the thrips popultions incresed. At the 3rd true lef stge, we hd out 42 thrips per seedling. Soil selection likely impcted our results, nd this tril is to e repeted using field soil rther thn potting soil mix in 2015 (Fig. 2). 83

88 At the frthest north loction, the Kress site, our untreted control plots hd over 20 thrips per plnt t the 1st true lef stge, while the treted plnts hd out 20 totl thrips on ll 10 seedlings. The 2nd smpling dte followed cool nd wet wether, nd we sw no difference in thrips numers etween tretments. This field site ws replnted to sorghum shortly following the 2nd smpling dte due to poor stnd fter dverse wether (Fig. 3). At the Hlfwy site, we oserved differences etween the two seed tretments nd the control t the first 2 smpling dtes. The control plnts for the first 2 smpling dtes hd out 1.3 thrips per plnt, ut y the third smpling dte, the thrips popultions hd decresed, nd were no longer significntly different (Fig. 4). 84

89 In College Sttion, we oserved difference etween control nd the 2 seed tretments t the first smpling dte. Thrips popultions hd declined y the 2nd smpling dte, following cool wether nd hevy rinfll (Fig. 5). The Wll, Lmes, nd Chillicothe sites showed no difference etween ny of the tretments, ut we lso did not oserve mny thrips t ny of these sites. (Figs. 6-8). 85

90 The College Sttion site ws the only one tht reched the threshold for thrips t ny point during the seson. This ws lso the only site we oserved difference in yield etween the tretments. Imidcloprid treted plots produced higher yield thn did the control plots, nd thimethoxm showed no significnt difference compred to imidcloprid or the control (Fig. 9). 86

91 Summry In conclusion, the seed tretments reduced thrips popultions in Kress, Hlfwy, nd College Sttion. The efficcy of these tretments decresed over time, s expected. Only one loction, College Sttion, hd thrips popultions to rech threshold nd influence yield significntly. At the College Sttion site, imidcloprid treted seed outyielded the control. Our greenhouse dt did not show significnt tretment effects, likely due to methodologicl resons with potting soil selection. In the future, we pln to repet the greenhouse trils with field soil insted of potting soil, nd repet the field trils in the sme loctions next yer. Acknowledgements This work ws conducted s prt of Kte Hrrell s MS thesis reserch. KH would like to thnk the Plins Cotton Growers ssocition, Cotton Incorporte nd the Texs A&M Agrilife Extension service for their support of this project. In ddition to my committee memers, I d lso like to thnk Mrk Arnold, Steven Biles, Stn Crroll, Tommy Doederlein, Jeffery Drymll, Jeff Hrrell, Cole Miller, Rick Minzenmyer, Richrd Normn, Pt Porter, Blyne Reed, Cesr Vlenci, Kerry Siders, Leslie Wells, nd Wending Zhou for their help with this reserch. References Burris E., K. J. Rtchford, A. M. Pvloff, D. J. Boquet, B. R. Willims, nd R. L. Rogers Thrips on seedling cotton: Relted prolems nd control. Louisin Agriculturl Experiment Sttion Bulletin 811. LSU AgCenter, Bton Rouge, LA. Herron, G. A., J. Rophil, nd G. C. Gullick Lortory-sed, insecticide efficcy studies on field-collected Frnkliniell occidentlis (Pergnde) (Thysnopter: Thripide) nd implictions for its mngement in Austrli. Austrlin Journl of Entomology 35: Immrju, J. A., T. D. Pine, J. A. Bethke, K. L. Ro, nd J. P. Newmn Western flower thrips (Thysnopter: Thripide) resistnce to insecticides in costl Cliforni greenhouses. Journl of Economic Entomology 85:

92 Stewrt, S Tocco thrips resistnce to Cruiser cotton seed tretment confirmed in Tennessee. Southest Frm Press, Novemer 8. Willims, M Cotton insect losses 2012, pp In Proc. Beltwide Cotton Conferences, Ntionl Cotton Council, Memphis, TN. Zho, G. Y., W. Liu, J. M. Brown, nd C. O. Knowles Insecticide resistnce in field nd lortory strins of western flower thrips (Thysnopter: Thripide). Journl of Economic Entomology 88:

93 BREEDING VALUE OF HOST PLANT THRIPS RESISTANCE FOR NEW CULTIVAR DEVELOPMENT D. Q. Wnn Texs A&M AgriLife Reserch nd Texs Tech University Luock, TX J. K. Dever M. N. Prjulee M. D. Arnold Texs A&M AgriLife Reserch Luock, TX Astrct Thrips (Thysnopter: Thripide) mngement is n importnt component of cotton production on the Texs High Plins. With the loss of systemic ldicr insecticides, host plnt resistnce cn e vlule tool for mitigting thrips injury to cotton seedlings. Understnding the nture nd reeding vlue of such resistnce is key for its utiliztion in cultivr development. Field nd greenhouse trils were conducted in to evlute genetic segregtion nd estimte rod sense heritility (H 2 ) nd ctul gin from selection (G s ). In 2011, n interspecific F 2 popultion ws grown in greenhouse tril to evlute genetic segregtion of the trit. Individul plnts were evluted for thrips feeding injury t 4-5 true leves, utilizing visul dmge rting scle. Phenotypic dt were continuously distriuted, nd susequent chi-squre nlyses confirmed tht the dt did not fit known single- or two-gene segregtion rtios (P < 0.05). A similr tril ws repeted t the field level in 2012, utilizing different interspecific F 2 popultion. Chi-squre nlyses gin suggested quntittive inheritnce of thrips resistnce (P < 0.05). Therefore, in , five fmilies, derived from interspecific crosses, were evluted in greenhouse trils to estimte the H 2 of thrips resistnce. Individul prent nd F 2 plnts were plnted nd visully ssessed for thrips dmge. H 2 vlues rnged 40-70%, depending on the fmily. F 2 nd F 3 popultions, resulting from n interspecific cross, were evluted t the field level in 2012 nd 2013, respectively, to estimte ctul gin per cycle of selection. A 10% selection intensity (SI) resulted in n pproximte 9% gin per cycle of selection; 5% SI resulted in 22% gin nd 1% SI resulted in only 3% gin. Given the potentil sensitivity of this trit to environmentl conditions, 5% SI ppered to optimize ctul genetic gin, wheres 1% SI ws likely too intense. Selection intensity should therefore e djusted ccording to mient thrips popultions in given loction, to ensure greter cpture of genetic effects through selection. These results suggest tht host plnt thrips resistnce in cotton is quntittively-inherited, with modertely high heritility. Significnt genetic improvement cn e therey chieved through visul selection, depending on selection intensity in given cycle. 89

94 2015 Beltwide Cotton Conferences, Sn Antonio, TX, Jnury 5-7, 2015 UTILIZATION OF NO-THRIPS CAGES TO QUANTIFY THRIPS-INDUCED LOSSES TO COTTON IN THE TEXAS HIGH PLAINS Adul Hkeem Megh Prjulee Texs A&M AgriLife Reserch nd Extension Center Luock, TX Texs produces 55% of U.S. cotton, of which, pproximtely 66% is produced in the Texs High Plins region. In 2013, rthropods cused 2.27% cotton yield loss in the U.S. Thrips infested 6.7 million cres of cotton in the U.S. in 2013, with 2.4 million cres infested in Texs. This infesttion cused 0.56% yield loss due to thrips nd rnked third mong rthropod-cused losses, with c. 7,000 les lost to thrips in Texs (Willims 2014). The western flower thrips, Frnkliniell occidentlis Pergnde, is mjor thrips pest on seedling cotton in Texs. Thrips re n erly seson pest which cn cuse severe dmge to seedling cotton. Thrips cuse dmge to seedling cotton nd excessive feeding leds to rowning of leves on the edges, develop silvery color, or curl upwrd from the edges nd cuse the loss of lef chlorophyll nd lef re. Thrips re very smll insects which mke it hrder to study them in enclosures. The ojective of this study ws to evlute No-Thrips cges (Green-Tek, Edgerton, WI) to study thrips ehvior. This study ws conducted t the Texs A&M AgriLife Reserch frm locted ner Luock, Texs. The study ws deployed in rndomized lock design with five replictions nd six tretments. Cotton cultivr ST 5458B2RF ws plnted on June 3, Rectngulr wooden-frme cges [98 cm (L) x 30 cm (W) x 44 cm (H)] with No-Thrips screen were constructed nd deployed in the field, with ech cge enclosing 8-13 cotton seedlings (Fig. 1). Silicone culk ws used to ttch No-Thrips screen to the wooden frme. A thin metl flshing ( cm) ws ttched t the ottom of the cge to restrict thrips movement from the ottom of the cge. A temperture sensor ws kept inside the cge to record the internl cge tempertures. Freshly collected dult thrips, primrily western flower thrips, were relesed t vrious densities to generte dmge grdient cross density tretments. Six thrips density tretments were relesed onto plnts on June 18 when the cotton seedlings were t the 1-2 true-lef stge. Six density tretments included 0, 1, 2, 4, 6, nd 10 thrips per plnt, replicted five times (totl 30 cges) plus n uncged control. Cges were removed on June 23 nd two plnts from ech cge were clipped t the se, secured in glss jr, nd wshed to retrieve thrips. After removl of cges, thrips ugmented rows were spryed with Orthene 97. The remining plnts from the cged sections were mintined reltively insect-free for the reminder of the growing seson, nd were hrvested upon crop mturity for lint yield. This study ws repeted for three phenologicl stges of cotton, ut only one dt set is presented in this pper. Figure 1. Wooden-frmed field cge covered with No-Thrips screen for threshold study (left); Instlltion of thrips cges in the field nd relese of thrips densities (right). No-thrips cges ppered to hold thrips in the field cges etter thn ny of the other field cge mterils (frics) tht we hve used in previous studies. Different mterils nd designs were used in the pst with very little success. Those designs included 1) trnsprent plstic cup cge, 2) wire mesh sleeve cge, 3) opque plstic cylinder, 4) trnsprent plstic jr without ventiltion, nd 5) trnsprent plstic jr with ventiltion (Fig. 2). None of these methods were suitle for thrips studies in the field ecuse of the excessive temperture uildup inside the cges, plus mteril of the screen ws unle to contin the thrips. However, the No-Thrips cge design provided stisfctory performnce. Unfortuntely, hevy rinfll within 48-hour of the thrips cge relese severely comprised our test in this study. Unusully cool wether during the thrips exposure period resulted in low thrips survivl nd reduced feeding on the cotton seedling tissues (Fig. 3). 90

95 6 Figure 2. Cge types evluted previously: 1) trnsprent plstic cup cge, 2) wire mesh sleeve cge, 3) opque plstic cylinder, 4) trnsprent plstic jr without ventiltion, nd 5) trnsprent plstic jr with ventiltion. Thrips recovered per tretment Thrips densities relesed per plnt Figure 3. Recovery of thrips from cotton seedlings 5-dys post-relese of vrying densities of thrips in No-Thrips cges. Although the thrips retrievl post-relese ws very low, it ppers tht the thrips feeding hd exerted some effect on plnt, resulting in reduced plnt height nd smller min-stem dimeter in ll thrips ugmented plnts compred to tht in control cges (Figs. 4-5). Nevertheless, the thrips feeding, if ny, during the seedling stge in this study did not significntly impct lint or seed yields (Figs. 6-7) Plnt height (cm) Thrips densities relesed per plnt Figure 4. Plnt height mesurements of cotton plnts t full mturity tht were infested with vrying densities of thrips in No-Thrips cges during the seedling stge. 91

96 13 Plnt dimeter (mm) Thrips densities relesed per plnt Figure 5. Plnt dimeter mesurements of cotton plnts t full mturity tht were infested with vrying densities of thrips in No-Thrips cges during the seedling stge. 170 Lint weight/tretment (g) Thrips densities relesed per plnt Figure 6. Lint weight from cotton infested with vrying densities of thrips in No-Thrips cges during the 1-2 truelef stge, Luock, Texs, Seed weight/tretment (g) Thrips densities relesed per plnt Figure 7. Seed weight from cotton plnts infested with vrying densities of thrips in No-Thrips cges during the 1-2 true-lef stge, Luock, Texs,

97 2015 Beltwide Cotton Conferences, Sn Antonio, TX, Jnury 5-7, 2015 USE OF A MODIFIED - VIRAL GENE TO CONFER RESISTANCE AGAINST APHIDS IN TRANSGENIC PLANTS Srny Gnpthy Megh N. Prjulee Hong Zhng Michel SnFrncisco Shn L. Bilimori Deprtment of Biologicl Sciences, Texs Tech University Luock, TX Astrct Use of chemicl insecticides, the predominnt control method thus fr, hs resulted in environmentl dmge, pest resurgence, nd negtive effects on non-trget species. Geneticlly modified crops offer promising lterntive, nd Bcillus thuringiensis toxin genes hve plyed mjor role in this respect. However, to overcome insect tolernce issues nd to roden the trget rnge, it is criticl to identify lterntive insecticidl toxins working through novel mechnism. Our group hs identified cot protein kinse from Chilo iridescent virus (CIV) tht hs insecticidl ctivity. The CIV toxin, expressed in yest systems, induces 50% mortlity in cotton phids nd 100% mortlity in green pech phids (GPAs). Our hypothesis is cloning this virl kinse gene into plnts will generte trnsgenic lines toxic for phids nd other pests. Expression of foreign genes in plnts is often complicted y codon usge, mrna instility, trnsltionl efficiency, nd proteolytic degrdtion. Therefore, the virl toxin gene ws codon optimized to fvor trnsltion nd stility in plnt. This optimized virl gene ws stly trnsformed into Aridopsis plnts. The stle lines expressing this toxin induced moderte to very high mortlity in GPAs nd significntly ffected its popultion growth. The phidicidl potentil of these trnsgenic Aridopsis lines will e presented. Our long term gol is to generte insect-resistnt cotton using the virl gene. This will ultimtely yield trnsgenic cotton cultivrs resistnt to pests other thn cterpillrs nd therefore e more profitle for US frmers in n incresingly competitive glol mrket. 93

98 2015 Beltwide Cotton Conferences, Sn Antonio, TX, Jnury 5-7, 2015 LATE SEASON LYGUS HESPERUS MANAGEMENT IN TEXAS COTTON Megh N. Prjulee Adul Hkeem Stnley C. Crroll Texs A&M AgriLife Reserch nd Extension Center Luock, TX Astrct A three-yer field cge study ws conducted to chrcterize the density-dependent oll feeding potentil of Lygus hesperus in Texs High Plins cotton. Lygus dmge to cotton olls t vrious Lygus densities ws determined. Individully cged cotton plnts were exposed to 4 levels of Lygus (0, 1, 2 nd 4 or 6 dults per cge) for one week when plnts were t two selected oll development stges (350 nd 550 HU >60 F fter first flower). When the crop mtured from 350 HU to 550 HU fter first flower, the percentge of olls vulnerle to Lygus feeding dmge ws reduced from 50% to 30%. Averged over three yers, rtificil ugmenttion of 1, 2, 4, nd 6 Lygus per plnt t 350 HU fter first flower reduced the cotton lint yield y 137, 313, 422, nd 516 l/cre, respectively, wheres the yield reduction vlues for the sme Lygus densities were 66, 191, 213, nd 415 l/cre during the lte seson (550 HU from first flower). Thus, the Lygus yield reduction potentil decresed y 52, 39, 50, nd 20% for 1, 2, 4, nd 6 Lygus per plnt infesttion when cotton mtured from 350 HU to 550 HU. A detiled understnding of Lygus oll feeding iology nd ehvior will e highly vlule in improving Lygus mngement decisions during the different oll developmentl stges. Introduction Cotton, Gossypium hirsutum L., is mjor csh crop in the U.S. nd worldwide. The U.S. is the world s third lrgest cotton producer nd the U.S. cotton industry is vlued t more thn $25 illion per yer. In Texs, pproximtely six million cres of cotton hve een plnted nnully in recent yers, nd Texs is the lrgest cotton producing stte (Willims 2013). Lygus hesperus is n importnt economic pest of cotton in some regions of the United Sttes nd it is n emerging pest of Texs High Plins cotton. In Texs, over 2 million cres of cotton were infested y Lygus in 2012 (Willims 2013). Lygus cn cuse severe cotton squre loss, nther dmge, nd seed dmge depending upon the crop growth stge the infesttion occurs. Both dult nd nymphl stges of Lygus cn inflict dmge to cotton fruiting structures. Lygus lte-instr nymphs re cple of inflicting greter internl dmge to mturing olls thn re dults, nd this ws especilly true for 1-2 week old ( HU) olls (Ju nd Crruth 1971, Prjulee et l. 2011). In the Texs High Plins region, Lygus generlly infest cotton fields during the ltter prt of the cropping seson, thus cusing dmge primrily to the cotton olls. Following the introduction of Bt-technology (Bollgrd cotton), outreks of lepidoptern pests hve een drsticlly reduced, nd in recent yers, secondry piercing-sucking pests such s Lygus re of incresing concern to Texs High Plins producers (Prjulee et l. 2008). Cotton oll profiles chnge s the crop mtures, nd s result, the numer of Lygus susceptile nd/or tolernt olls to Lygus dmge lso chnge. As oll mturity profiles chnge, Lygus oll selection nd feeding ehvior my lso chnge which cn result in different levels of crop injury nd yield loss. There is strong reltionship etween oll mturity nd Lygus feeding dmge, thus understnding the oll mturtion profile nd chrcterizing Lygus dmge risk dynmics is importnt. The ojective of this study ws to quntify the yield loss cused y 4 different levels of Lygus infesttions (0, 1, 2 nd 4 or 6 Lygus dults per plnt). The overll gol is to etter understnd the oll feeding iology nd ehvior of Lygus hesperus in order to further develop dynmic economic threshold for improved Lygus mngement in Texs High Plins cotton. Mterils nd Methods A field study ws conducted to quntify the effect of Lygus density nd infesttion timing on cotton yield nd fier qulity. Cotton cultivr ST 5458B2RF ws plnted on My 18 (2012), My 22 (2013), nd My 15 (2014) in dripirrigted field with 40-inch row spcing t the Texs A&M AgriLife Reserch frm locted ner Luock, Texs. The trgeted seeding rte ws 56,000 seeds per cre. On June 2, the 2012 study ws treted with Orthene 97S for thrips t rte of 3.0 oz per cre nd with Cornerstone Plus hericide (41% glyphoste) t 32 oz per cre for weed mngement, wheres the 2013 nd 2014 study plots did not receive insecticide interventions for thrips control nd weeds were removed vi cultivtion nd hnd-hoeing. 94

99 The field study ws lid out in split-plot rndomized lock design with three replictions, two min plot fctors [two cotton oll developmentl stges (erly oll development nd lte oll development)], nd four suplot fctors [four levels of Lygus infesttion (control or zero ugs, one ug/plnt, two ugs/plnt, nd four or six ugs/plnt)]. There were totl of 24 experimentl units. Ech experimentl unit hd 8 cotton plnts s susmples (3 used for dmge ssessment nd 5 for yield nd qulity ssessment). A totl of 192 whole-plnt sleeve-cged cotton plnts (three locks x two cotton oll stges x four Lygus densities x eight susmples) were used for this study (Fig. 1). Figure 1. Field deployment of whole-plnt cges for Lygus threshold study, Luock, TX, The cotton field study site ws closely monitored nd kept virtully rthropod pest-free until cges were deployed on July 24, July 29, nd July 28 in 2012, 2013, nd 2014, respectively. When the cotton plnts reched the trget mturity level (350 HU fter first flower on August 7, August 13, nd August 17 in 2012, 2013, nd 2014, respectively, nd 550 HU fter first flower on August 21, August 29, nd August 27 in 2012, 2013, nd 2014, respectively), l-rered Lygus were relesed into the whole-plnt sleeve-cges t the rtes of 0, 1, 2, nd 4 ugs/plnt in 2012 nd 2013; the infesttion densities were chnged to 0, 2, 4, nd 6 ugs/plnt in 2014 to increse the dmge intensity. Lygus dults were collected from nery lflf field or from lflf in djcent counties nd cclimtize in the lortory for 48 hours efore using them for the oll feeding experiment. Cotton plnts were exposed to the Lygus dults for ~7 dys, fter which time, the insects were killed vi pesticide ppliction. Three rndomly selected cotton plnts from ech plot were cut nd rought to the lortory on August 13, August 19, nd August 27 for the 350 HU nd August 29, Septemer 2, nd Septemer 5 for the 550 HU plots in 2012, 2013, nd 2014, respectively. The cotton crop ws defolited y sprying FOLEX 6EC (12 oz per cre) nd oll opener (Ethephon 6; 32 oz per cre) in tnk mix in ll three yers of the study. After the crop ws redy to hrvest, the remining 5 cged plnts from ech plot, which hd een mintined pest-free, were hrvested mnully to evlute the lint yields nd fier qulity. Hrvested singleplnt smples were ginned individully vi tle-top gin nd smples were nlyzed for fier qulity (HVI) prmeters t Cotton Incorported. Dt from the whole-plnt cge study were summrized y clculting verge nd stndrd errors. ANOVA, GLM model (SAS Institute 2010) ws used to evlute the tretment effects (α=0.1) nd tretment mens were compred y LSMEAN procedure. Results nd Discussion In generl, s expected, Lygus ugmenttion reduced the lint yield compred to tht in uninfested control cges (Figs. 2-4). However, the dmging effect of Lygus ws more pronounced during mid-seson (350 HU from first flower) compred to tht in lte seson (550 HU from first flower) for ll three yers of the study. Although yer-to-yer vrition existed, Lygus ugmenttion of 1 dult per cge did not significntly decrese the lint yield, ut the higher densities reduced the yield significntly compred to tht in uninfested cges. In 2012, rtificil ugmenttion of 1, 2, nd 4 Lygus ugs per plnt t 350 HU fter first flower reduced the cotton lint yield y 116, 425, nd 580 l/cre, respectively, wheres the yield reductions for the sme Lygus densities were 125, 149, nd 185 l/cre during the lte seson (550 HU from first flower) (Fig. 2). In 2013, cotton lint yields in mid-seson plots (cges) were much lower thn in 2012, ut the ugmenttion of 1, 2, nd 4 Lygus ugs per plnt reduced the cotton lint yield y 157, 106, nd 281 l/cre, respectively (Fig. 3). While these lint yield reduction vlues were not sttisticlly significnt, owing to greter vrition in dt, the trend ws convincingly supportive of cler influence of Lygus ugmenttion on yield reduction nd the dt trend ws similr to tht in Overll, lint yield ws higher in lte-seson test plnts compred to tht in mid-seson test plnts, ut 95

100 the ugmenttion of 1 Lygus per plnt did not result in significnt yield reduction, wheres 2 nd 4 Lygus per plnt reduced 143 nd 159 l/cre, respectively (Fig. 3). In 2014, ugmenttion of 2, 4, nd 6 Lygus per plnt t 350 HU fter first flower reduced the cotton lint yield y 407, 406, nd 516 l/cre, respectively, wheres the yield reductions for the sme Lygus densities were 282, 295, nd 415 l/cre during the lte seson (550 HU from first flower) (Fig. 4). Overll yield in 2014 ws higher thn in 2012 nd 2013, ut the dmge inflicted y 2 nd 4 Lygus per plnt on mid-seson cotton ws comprle to tht for 2012, wheres the dmge inflicted in lte seson cotton ws higher in 2014 compred to tht in 2012 or Lygus-induced lint yield reduction for given Lygus density ws lower for lte seson compred to tht for mid-seson infesttion in ll three yers of the study (Figs. 2-4). These dt clerly suggest tht the mturing olls re more tolernt to Lygus injury when the plnt ttins 550 HU from first flower. It is lso possile tht Lygus ugs my choose to feed on superfluous olls or squres nd the yield contriuting fruits my not e significntly impcted y such lte infesttion. Becuse potentil yield loss risks due to certin Lygus density infesttions vry with oll mturtion profile, the Lygus mngement economic threshold should e optimized for dynmic ET to ccommodte for withinplnt fruit mturity profiles. Figure 2. Influence (pounds of yield reduction) of vrying levels of Lygus infesttions on lint yield t two crop phenologicl stges, Luock County, TX, Figure 3. Influence (pounds of yield reduction) of vrying levels of Lygus infesttions on lint yield t two crop phenologicl stges, Luock County, TX,

101 Figure 4. Influence (pounds of yield reduction) of vrying levels of Lygus infesttions on lint yield t two crop phenologicl stges, Luock County, TX, Averged over three yers, rtificil ugmenttion of 1, 2, 4, nd 6 Lygus per plnt t 350 HU fter first flower reduced the cotton lint yield y 137, 313, 422, nd 516 l/cre, respectively, wheres the yield reduction vlues for the sme Lygus densities were 66, 191, 213, nd 415 l/cre during the lte seson (550 HU from first flower). Thus, the Lygus yield reduction potentil decresed y 52, 39, 50, nd 20% for 1, 2, 4, nd 6 Lygus per plnt infesttion when cotton mtured from 350 HU to 550 HU. Lte seson Lygus mngement progrm my consider decresing Lygus dmge potentil s seson progresses nd djust the economic threshold (ET) ccordingly. We re currently developing dynmic ET for Lygus mngement in the Texs High Plins. Acknowledgements We thnk the Cotton Incorported Texs Stte Support Committee nd Plins Cotton Growers, Inc. for funding of this reserch. The uthors lso re indeted to Richrd Normn, Jeffrey Drymll, Betsy Perfn, Sydnee Woodmn, Christy Hogue, nd Json Siz, whose technicl ssistnce in the field ws invlule. References Ju, Jr. G. L., nd L. A. Crruth Growth nd yield of cged cotton plnts infested with nymphs nd dults of Lygus hesperus. J. Econ. Entomol. 64: Prjulee, M. N., R. B. Shresth, A. K. Brmn, nd S. C. Crroll Ecologiclly intensive pest mngement in cotton groecosystems: Lygus hesperus s model system. Egyptin Journl of Agriculturl Reserch 86: Prjulee, M. N., M. B. Adhikri, D. L. Kerns, R. B., Shresth, nd S. C. Crroll Insecticide termintion rule for western trnished plnt ug in the Texs High Plins, pp In Proceedings, Beltwide Cotton Conferences, Ntionl Cotton Council, Memphis, TN. Willims, M. R Cotton insect losses-2012, pp In Proceedings, Beltwide Cotton Conf., Ntionl Cotton Council, Memphis, TN. 97

102 2015 Beltwide Cotton Conferences, Sn Antonio, TX, Jnury 5-7, 2015 UPDATE ON BOLLWORM PYRETHROID RESISTANCE MONITORING Fred R. Musser Mississippi Stte University Mississippi Stte, MS Jeremy K. Greene Clemson University Blckville, SC D. Ames Herert Virgini Tech Suffolk, VA Moneen Jones University of Missouri Portgeville, MO Dvid Kerns LSU AgCenter Winnsoro, LA Gus M. Lorenz University of Arknss Little Rock, AR Megh N. Prjulee Texs A&M AgriLife Reserch nd Extension Luock, TX Dominic Reisig North Crolin Stte University Plymouth, NC Phillip M. Roerts University of Georgi Tifton, GA Scott D. Stewrt The University of Tennessee, WTREC Jckson, TN Astrct Polyphgous ollworms re potentilly exposed to pyrethroid insecticides during ech genertion. Since cotton is host during the ltter prt of the growing seson, ny resistnce developed during the seson will reduce control relized in cotton. Pheromone trps hve een used spordiclly since the lte 1980s throughout the cotton elt to collect mle moths for testing resistnce to pyrethroid insecticide. Testing ws conducted cross the cotton elt in coordinted fshion from using concentrtion of 5 µg/vil of cypermethrin s the dignostic dose. Overll survivl during 2014 ws 18.8%, which ws somewht higher thn recent yers. However, resistnce ws not uniform cross ll sttes. Louisin nd Virgini hve regulrly hd higher survivl thn ll other sttes during recent yers. This yer Georgi joined them with ll hving yerly verge survivorship etween 30 nd 35%. In contrst, Missouri, South Crolin nd Tennessee ll hd verge survivl of less thn 10%. The other sttes fell etween these extremes. Introduction Bollworm, Helicoverp ze, is pest in numerous crops where it my e exposed to pyrethroid insecticides. Since it cn hve 5 or more genertions per yer in the southern U.S., it hs the potentil to develop lrge popultions nd insecticide resistnce hs the potentil to develop nd spred rpidly. One to two of these genertions occur in cotton, cusing sustntil economic loss. Becuse pyrethroid insecticides re reltively inexpensive, they re often the first choice of growers for folir control of ollworms. Knowledge of the susceptiility of ollworms to pyrethroid insecticides is therefore criticl to effective mngement of this pest. Monitoring pyrethroid resistnce in ollworms hs een conducted for numerous yers, eginning in 1988 in few sttes nd then coordinted throughout the cotton elt in (Rogers et l. 1990). Since then monitoring hs continued t vrious levels every yer. Regionl dt from previous yers cn e found in erlier Beltwide cotton 98

103 conference proceedings (Mrtin et l. 1999, 2000, Pyne et l. 2001, 2002, Musser et l. 2010, 2011, 2013). During this time the iossy methodology hs remined consistent. Mle moths re cptured in pheromone trp nd plced in glss vil tht ws previously treted with insecticide. Mortlity is recorded fter 24 h. A concentrtion of 5 µg cypermethrin / vil hs een used with seline survivl generlly less thn 10% (Mrtin et l. 1999). Mterils nd Methods Hrtstck pheromone trps were plced in vrious loctions in ten sttes cross the cotton elt from VA to TX. Pheromones (Luretpe with Zelure, Hercon Environmentl) were chnged every 2 weeks. Some trps were monitored t lest weekly from My until Septemer, ut most were monitored over shorter period when ollworms were undnt nd cotton ws susceptile to ollworm feeding. Helthy moths cught in these trps were susequently tested for pyrethroid resistnce. Moths were individully plced in 20 ml scintilltion vils tht hd een previously coted with 0 or 5 µg cypermethrin per vil. Vil preprtion for ll loctions except Louisin ws done t Strkville, MS nd shipped to coopertors s needed throughout the yer. Louisin dt re from vils prepred in Louisin. In ddition to rtes of 0 nd 5 µg cypermethrin per vil, Louisin lso tested survivl t 10 µg cypermethrin per vil. At ll loctions, moths were kept in the vils for 24 h nd then checked for mortlity. Moths were considered ded if they could no longer fly. Reported survivl ws corrected for control mortlity (Aott 1925). Results nd Discussion A totl of 8815 moths were ssyed during The fewest moths (169) were tested in North Crolin while the most moths (2539) were tested in Louisin. Averge survivl to the 5 µg cypermethrin / vil concentrtion ws 18.8% in 2014 (Tle 1), which ws the highest rte of survivl since 2007 (Fig. 1). As hs een consistently oserved in the pst, survivl during July ws higher thn during previous months. While lte seson moths re often more susceptile, survivl rtes during 2014 were mintined during August nd Septemer. Tle 1. Bollworm survivl to 5 µg cypermethrin per vil in 24-h vil tests during Totl ollworms Stte My June July Aug Sep Overll tested AR GA LA MS MO NC SC TN TX VA Averge

104 Fig. 1. Beltwide ollworm verge survivl per yer t 5 µg cypermethrin per vil from Most sttes hd survivl rtes similr to previous yers, put survivl in Georgi ws shrply higher during 2014, mking verge survivl in Georgi for the yer similr to Louisin nd Virgini, the two sttes tht hve hd the lest susceptile moths during the lst severl yers (Fig. 2). Whether this is one-yer spike like oserved in 2007, or long-term chnge in susceptiility remins to e seen. North Crolin hs lso hd higher survivl thn most sttes ech of the lst two yers, so it my e tht pyrethroid resistnce in ollworms is ecoming more common long the estern cost of the U.S. Fig. 2. Averge ollworm survivl y stte per yer t 5µg cypermethrin per vil from A comprison of ollworm susceptiility in Louisin t oth 5 µg nd 10 µg cypermethrin, revels tht the reltionship etween these concentrtions is not the sme throughout the yer. While survivl during My nd June ws similr t oth concentrtions, survivl continued to increse throughout the yer t 5 µg, ut styed stedy 100

105 etween 20% nd 30% survivl t 10 µg (Fig. 3). For point of reference, tocco udworm ws considered resistnt to pyrethroids when there ws 30% survivl of the moths t the 10 µg concentrtion. Louisin styed ner this line most of the yer, nd lrvl control of ollworms with pyrethroids is considered errtic. Fig. 3. Monthly ollworm survivl t 5 µg nd 10 µg cypermethrin per vil in Louisin during Bollworm dults re considered highly moile (Lingren et l. 1994, Beerwinkle et l. 1995), which would suggest tht pyrethroid resistnce would quickly spred from one region to nother. However, pyrethroid resistnce hs persisted in LA nd VA for numerous yers while popultions in djcent sttes remin lrgely susceptile. Field control of ollworm lrve is inconsistent throughout mny prts of the cotton elt, so it is likely tht numerous resistnce genes re present in popultions. It is likely tht resistnce is ssocited with high fitness costs, so resistnce is reduced every winter, nd spreds to new regions more slowly thn expected. However, monitoring from found verge survivl rtes of less thn 10%, while verge current survivl is pproching 20% nd exceeds 30% in some sttes. Even though pyrethroids my not e pplied s frequently in cotton s in the pst, there re still enough pplictions mde in the lndscpe to slowly decrese pyrethroid susceptiility, mking the selection of this clss of chemistry for trgeting ollworms risky decision. Conclusions Pyrethroid susceptiility in ollworms over the cotton elt ppers to e slowly decresing, ut the rte of decline is not uniform. Louisin nd Virgini hve hd the lowest susceptiility for severl yers. Georgi hs similr survivl to pyrethroids during Averge survivl on 5 µg cypermethrin over the entire cotton elt rose to 18.8% during 2014, which ws the highest survivl oserved since Acknowledgements The uthors thnk Cotton Inc. nd ll the cooperting universities for providing prtil funding for this project. References Aott, W. S A method of computing the effectiveness of n insecticide. J. Econ. Entomol. 18: Beerwinkle, K. R., J. D. Lopez, D. Cheng, P. D. Lingren, nd R. W. Meol Flight potentil of ferl Helicoverp ze (Lepidopter: Noctuide) mles mesured with 32-chnnel, computer-monitored, flight-mill system. Environ. Entomol. 24:

106 Lingren, P. D., J. K. Westrook, V. M. Brynt, J. R. Rulston, J. F. Esquivel, nd G. D. Jones Origin of corn erworm (Lepidopter: Noctuide) migrnts s determined y citrus pollen mrkers nd synoptic wether systems. Environ. Entomol. 23: Mrtin, S. H., R. D. Bgwell, M. L. Boyd, B. L. Freemn, G. A. Herzog, D. R. Johnson, M. B. Lyton, B. R. Leonrd, N. Liu, G. T. Pyne, P. V. Pietrntonio, M. E. Roof, M. J. Sullivn, J. W. Vn Duyn, nd J. R. Weeks Sttus of ollworm, Helicoverp ze, susceptiility to pyrethroids: IRAC-US 1998 updte, pp In: Proceedings, Beltwide Cotton Conferences. 3-7 Jnury, Orlndo, FL. Ntionl Cotton Council, Memphis, TN. Mrtin, S. H., J. S. Bchelor, R. D. Bgwell, M. L. Boyd, B. L. Freemn, G. A. Herzog, D. R. Johnson, M. B. Lyton, B. R. Leonrd, N. Liu, G. T. Pyne, P. V. Pietrntonio, M. E. Roof, R. Sewrd, R. K. Sprenkel, M. J. Sullivn, J. W. Vn Duyn, nd J. R. Weeks Sttus of ollworm, Helicoverp ze, susceptiility to pyrethroids in the mid-south nd southest: IRAC-US 1999 updte, pp In: Proceedings, Beltwide Cotton Conferences. 4-8, Jnury, Sn Antonio, TX. Ntionl Cotton Council, Memphis, TN. Musser, F. R., R. E. Jckson, J. K. Greene, B. R. Leonrd, S. D. Stewrt, M. N. Prjulee, J. J. Admczyk, G. M. Lorenz, D. S. Akin, K. V. Tindll, D. A. Herert, nd P. M. Roerts Pyrethroid resistnce monitoring of ollworms, pp In: Proceedings, Beltwide Cotton Conferences. Jn. 4-7, New Orlens, LA. Ntionl Cotton Council, Memphis, TN. Musser, F. R., R. E. Jckson, J. K. Greene, B. R. Leonrd, S. D. Stewrt, M. N. Prjulee, J. J. Admczyk, G. M. Lorenz, D. S. Akin, K. V. Tindll, D. A. Herert, nd P. M. Roerts pyrethroid resistnce monitoring of ollworms, pp In: Proceedings, Beltwide Cotton Conferences. Jn. 4-7, Atlnt, GA. Ntionl Cotton Council, Memphis, TN. Musser, F. R., R. E. Jckson, J. K. Greene, D. Kerns, S. D. Stewrt, M. N. Prjulee, R. D. Prker, G. M. Lorenz, A. Jones, D. A. Herert, nd P. M. Roerts Beltwide pyrethroid resistnce monitoring of ollworms, pp In: Proceedings, Beltwide Cotton Conferences. Jn. 7-10, Sn Antonio, TX. Ntionl Cotton Council, Memphis, TN. Pyne, G. T., J. S. Bchelor, J. W. Vn Duyn, R. D. Bgwell, B. R. Leonrd, M. L. Boyd, B. L. Freemn, N. Liu, J. R. Weeks, A. Herert, G. A. Herzog, D. R. Johnson, M. B. Lyton, G. L. Lentz, R. Sewrd, S. H. Mrtin, P. V. Pietrntonio, M. E. Roof, M. J. Sullivn, nd R. K. Sprenkel U.S. Cottonelt survey: testing the susceptiility of the ollworm, Helicoverp ze (Boddie) to pyrethroid insecticides, pp In: Proceedings, Beltwide Cotton Conferences Jnury, Anheim, CA. Ntionl Cotton Council, Memphis, TN. Pyne, G. T., J. Admczyk, J. S. Bchelor, R. D. Bgwell, M. L. Boyd, C. Brister, B. L. Freemn, A. Herert, G. A. Herzog, D. R. Johnson, M. B. Lyton, G. L. Lentz, B. R. Leonrd, N. Liu, S. H. Mrtin, P. V. Pietrntonio, M. E. Roof, R. K. Sprenkel, M. J. Sullivn, J. W. Vn Duyn, nd J. R. Weeks U.S. cottonelt survey: testing the susceptiility of the ollworm, Helicoverp ze (Boddie), to pyrethroid insecticides updte. In: Proceedings, Beltwide Cotton Conferences Jnury, Atlnt, GA. Ntionl Cotton Council, Memphis, TN. Rogers, B., H. D. Feese, S. L. Riley, C. A. Stetz, J. Whitehed, nd W. Mullins Heliothis resistnce monitoring in the cotton elt: PEG-US updte, pp In: Proceedings, Beltwide Cotton Conferences. Ls Vegs, NV. Ntionl Cotton Council, Memphis, TN. 102

107 VOL. 40, NO. 3 SOUTHWESTERN ENTOMOLOGIST SEP Moisture Conditions for Lortory Rering of Cotton Flehoppers 1 from Overwintered Eggs Lid on Woolly Croton Plnts Adul Hkeem nd Megh N. Prjulee* Texs A&M AgriLife Reserch nd Extension Center, 1102 E FM 1294, Luock, TX Astrct. The cotton flehopper, Pseudtomoscelis seritus (Reuter), is n economic pest of Texs cotton, Gossypium hirsutum L., tht feeds on nd cuses ortion of erly-stge squres. Cotton flehopper eggs re lid in lte fll nd overwinter on woolly croton, Croton cpittus Michx. Cotton flehoppers terminte dipuse in erly spring in response to minimum required temperture nd moisture conditions. A lortory study quntified the effects of different mounts of moisture (soking durtions of field-collected ded woolly croton plnts) on the emergence of cotton flehopper nymphs from dipused eggs. Five moisture tretments evluted were: 1) 24-hour initil soking nd no further moistening of the sustrte for the reminder of emergence durtion (T 1 ); 2) 2-hour initil soking followed y dily mist sprying of the sustrte (T 2 ); 3) 2-hour initil soking followed y 30-minute soking for the next 7 dys nd therefter mist sprying dily (T 3 ); 4) 2-hour initil soking followed y 30-minute soking for the next 7 dys nd therefter dipping the sustrte in wter dily (T 4 ); nd 5) soking for 15 minutes every other dy (T 5 ). Emergence of nymphs strted 6 dys fter initil incution in T 3, while the ltest emergence ws recorded from T 2. Pek nymphl emergence ws recorded 12-dys fter incution. Significntly more (P = 0.05) nymphs emerged from T 4 (n = 425) nd T 3 (n = 404) thn from T 1 (n = 173), T 2 (n = 290), or T 5 (n = 293). To mximize flehopper emergence from overwintered eggs in lortory, it ws recommended tht egg htching e ctivted y soking host sustrte (croton) for 30 minutes dily for out 7 dys nd keeping the sustrte moist throughout the emergence period. Introduction The cotton flehopper, Pseudtomoscelis seritus (Reuter) (Hemipter: Miride), is n importnt pest of cotton, Gossypium hirsutum L., in Texs nd Oklhom, nd n occsionl pest in Arknss, Louisin, New Mexico, nd other sttes in the mid-south (Wlker et l. 1970, Esquivel nd Esquivel 2009). Cotton flehopper is smll insect with piercing-sucking mouthprts tht feeds on erlystge (pinhed) cotton squres, cusing shedding of ffected squres nd potentil yield loss (Reinhrd 1926, Almnd 1974, Prjulee et l. 2006). At lest 160 plnt species in 35 fmilies including pinkldies, Oenother specios Nutt.; upright pririe 1 (Hemipter: Miride) *Corresponding uthor e-mil: m-prjulee@tmu.edu 103

108 coneflower, Rtiid columnifer (Nutt.) Woot. & Stndl.; silverlef nightshde, Solnum elegnifolium Cvnilles; nd woolly croton, Croton cpittus Michx. re hosts for the cotton flehopper (Snodgrss et l. 1984, Esquivel nd Esquivel 2009). Woolly croton is host of flehopper dults throughout the growing seson nd for overwintering eggs (Almnd 1974). In lte fll, cotton flehoppers ly eggs tht overwinter on host plnts until erly spring. Wrm tempertures nd spring rinfll events ctivte dipused eggs to emerge s nymphs. In lortory, Sunders (1983) terminted dipuse y controlled temperture, light, nd moisture. Despite its intriguing overwintering iology nd host-ssocited differentition (Brmn et l. 2012), informtion is limited on the ecology of cotton flehopper overwintering in semi-rid environment such s the Texs High Plins. While cotton flehoppers frequent cotton in most cotton-growing sttes, they re considered pestiferous primrily in Texs. In Texs, the cotton flehopper is more prevlent in the Costl Bend nd Brzos Vlley ut is n eqully importnt economic pest on the Texs High Plins, Rolling Plins, nd in the Trns-Pecos region. While the cotton flehopper cn significntly reduce the yield of cotton lint (Willims 2013), timing of cotton flehopper infesttion nd cotton cultivr nd inputs (e.g., irrigtion nd fertility) could ffect the severity of dmge nd the compenstory response of the plnt to injury (Chen et l. 2007, Knutson et l. 2013). Severl field reserch projects re underwy in our progrm to elucidte field ecology in reltion to cotton cultivr, irrigtion, nd fertility nd develop mngement strtegies ginst cotton flehopper. These efforts require lrge numers of stge-specific cotton flehoppers to relese in field plots. In ddition, studies of ehviorl response to resistnt hosts in lortory or greenhouse lso require consistent supply of cotton flehoppers. Lrge-scle field collection of cotton flehoppers for controlled studies is rrely fesile. However, cotton flehoppers cn e rered with predictle success in lortory y collecting ded croton plnts from res with undnt flehoppers in the winter. To rer cotton flehoppers successfully, host sustrte such s croton twigs tht contin overwintering eggs needs to e soked to ctivte htching of the eggs, nd these requirements might vry with regionl mient humidity. Currently, no dt re ville on rering methods for drier regions such s the Texs High Plins. A rering study in lortory t Texs A&M AgriLife Reserch nd Extension Center Cotton Entomology Progrm t Luock chrcterized cotton flehopper emergence from overwintered eggs. The ojective of the study ws to evlute the effects of soking durtion of woolly croton on the emergence of cotton flehopper nymphs from overwintered eggs. Mterils nd Methods Stnding, ut ded twigs of woolly croton, C. cpittus (Figs. 1A,B), were collected from the Brzos Vlley (College Sttion, TX re), in Jnury 2013 (Gylor nd Sterling 1975). Croton twigs were stored t 4ºC in wlk-in cooler (Fig. 1C). The twigs (110 g) were cut into 27-cm lengths nd plced in cylindricl 3.79-liter tin metl continers (pproximtely 27.5 cm tll nd cm in dimeter). Both ends of the rering continer were covered with corse-mesh luminum window screen to hold the croton in plce yet llow newly emerged cotton flehopper nymphs to exit from the rering sustrte. Another lyer of muslin cloth ws plced on top of the first screen nd secured y ruer nd to enclose newly emerged flehopper nymphs until shking to dislodge them from the 104

109 sustrte (Figs. 1D,E). Five moisture tretments with four replictions (tin cns) were: 1) 24-hour initil soking nd no further moistening of the sustrte for the reminder of emergence durtion (T 1 ); 2) 2-hour initil soking followed y dily mist sprying the sustrte (T 2 ); 3) 2-hour initil soking followed y 30-minute soking for the next 7 dys nd therefter mist sprying dily (T 3 ); 4) 2-hour initil soking followed y 30-minute soking for the next 7 dys nd therefter dipping the sustrte in wter dily (T 4 ); nd 5) soking for 15 minutes every other dy (T 5 ). The lst tretment (T 5 ) dpted from Breene et l. (1989) ws used s check (Fig. 1D). An experimentl check would hve een tretment with no moisture, ut such tretment is unrelistic ecuse cotton flehoppers do not emerge from dipusing eggs without moisture ctivtion. Woolly croton ws soked in wter to provide moisture to eggs deposited under the rk y flehopper dults (Fig. 1F). Nymphs (Fig. 1G) tht emerged from eggs were fed fresh green ens, Phseolus Fig. 1. A) Actively growing woolly croton plnt, B) dry woolly croton with dipusing cotton flehopper eggs in situ, C) woolly croton twigs collected nd stored in wlkin cooler, D) rrngement of the dipuse termintion nd rering experiment, E) rering continer (3.79-liter tin metl cn) with 110 g croton twigs per experimentl unit, F) cotton flehopper egg under croton rk (exposed), G) cotton flehopper nymph, nd H) cotton flehopper dult. 105

110 vulgris L., until dulthood (Fig. 1H) for other ehviorl experiments. Incution ws initited on 19 July The rering room ws mintined etween verge dily cool nd wrm tempertures of 25 nd 34ºC nd photoperiod of 12:12 light:drk hours (Fig. 2). Temporrily removing the muslin cloth nd shking the rering cns to dislodge emerging nymphs from the sustrte egn on the 5 th dy of the experiment nd continued for the next 4 weeks. Rering cns were shken dily y eting the sides of the cns 12 times t 2-second intervls to dislodge nymphs onto white poster ord. Dislodged nymphs were counted nd trnsferred into smll plstic continers nd fed green ens. Results A totl of 6,344 cotton flehopper nymphs emerged from the totl of 2,200 g croton sustrte. Significntly more (P < 0.05) nymphs emerged per 110 g of croton sustrte from the T 4 tretment [2-hour initil soking followed y 30-minute soking for the next 7 dys nd then dily dipping the sustrte in wter therefter (n = 425 ± 22)] nd T 3 [2-hour initil soking followed y 30-minute soking for the next 7 dys nd mist sprying dily (n = 404 ± 6)], followed y T 2 [2-hour initil soking followed y dily mist sprying the sustrte (n = 290 ± 12)] nd T 5 [soking for 15 minutes every other dy (n = 294 ± 35)], nd the fewest nymphs emerged from the T 1 tretment [24-hour initil soking nd no further moistening of the sustrte for the reminder of emergence (n = 173 ± 36)] (Fig. 3). Cotton flehopper emergence egn 6 dys fter initil soking t 24-36ºC in T 3 while the lst cotton flehopper nymph emerged from the host (croton) 32 dys fter the initition of incution in T 2. The temporl pttern of nymphl emergence ws similr cross the five moisture tretments, with pek emergence occurring 11 or 12 dys fter initition of dipuse termintion (Fig. 4). Nevertheless, the size of the emergence pek nd durtion of emergence vried cross tretments. The lrgest 1-dy emergence (153 nymphs per 110 g croton) occurred 12 dys fter incution in T 4 (2 hours initil sok, then 30-minute sok for 7 dys, therefter dipping) Min Mx Tempertures ( C) Jul 21-Jul 25-Jul 29-Jul 2-Aug 6-Aug 10-Aug 14-Aug 18-Aug 22-Aug 26-Aug Fig. 2. Dily tempertures recorded in the lortory when cotton flehoppers were rered from overwintering eggs, Luock, TX,

111 Fig. 3. Totl numer of cotton flehopper nymphs emerged per experimentl unit (110 g croton per unit) under five moisture regimes, Luock, TX. Fig. 4. Averge dily emergence of cotton flehopper nymphs per 110 g of croton sustrte under five moisture regimes, Luock, TX