Survey of Soil Arthropod Pests and Assessment of Yield Loss in Peanut in Northern Ghana

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1 Survey of Soil Arthropod Pests nd Assessment of Yield Loss in Penut in Northern Ghn M. Abuduli 1, I.K. Dzomeku 2, D. Opre-Atkor 1, S.K. Nutsugh 1, A.B. Slifu 1, R.L. Brndenburg 3 *, nd D.L. Jordn 3 ABSTRACT Soil rthropod pests re importnt constrints to penut production in Ghn. Surveys of penut fields were conducted from to identify nd estimte densities of key soil rthropod pests, nd lso to quntify their dmge to penut in the three regions (Northern, Upper Est nd Upper West) of northern Ghn. The min soil pests were termites (Isopter: Termitide), millipedes (Myripod: Odontopygide), white grubs (Coleopter: Scrbeide) nd wireworms (Coleopter: Elteride). Across regions, termites nd millipedes were the most bundnt while wireworms were the lest recorded. Significntly higher pest densities nd pod dmge by scrifiction nd penetrtion were generlly recorded in the Northern Region thn in the Upper Est nd Upper West Regions. A checklist dministered to frmers during the survey showed tht no control prctices were crried out for the pests though frmers generlly were wre of the dmging effects of these pests on penut. Field studies lso were conducted t Nynkpl nd Bgurugu in the Northern Region during 2005 nd 2006 to determine the effects of insecticide (chlorpyrifos or crbofurn) pplictions to penut t plnting, pegging or t both plnting nd pegging on control of soil rthropod pests nd on yield. Results showed tht the insecticides used were similr in their efficcy ginst the pests. Generlly, insecticide tretment lowered pest densities nd pod dmge resulting in incresed yield over the untreted control. Yield losses in untreted plots rnged between 23 nd 39%. Tretment t plnting or pegging did not differ in the level of control compred with tretment t both plnting nd pegging. Yield ws negtively correlted with pest densities nd pod dmge. These findings re discussed in the context of control of soil pests of penut in Ghn. Key Words: Penut, soil rthropod pests, yield loss ssessment, insecticides. 1 CSIR-Svnn Agriculturl Reserch Institute, P. O. Box TL 52, Tmle, Ghn. 2 University for Development Studies, P. O. Box TL 1385, Tmle, Ghn. 3 North Crolin Stte University, Rleigh, N.C 27695, USA. *Corresponding uthor s emil: rick_brndenburg@ncsu.edu Penut, Archis hypoge Linn is n importnt crop in Ghn, prticulrly in northern Ghn, which comprises the Northern, Upper Est nd Upper West Regions, nd ccounts for 92% of the totl ntionl production [Sttistics, Reserch nd Informtion Directorte (SRID), 2004]. The kernel hs high protein nd oil content nd is importnt both s humn food nd source of cooking oil. Revenue from the sle of the kernels is n importnt source of income to frmers. Additionlly, penut hy is used extensively s fodder for livestock, prticulrly during the dry seson fter the crop hs been hrvested (Nturl Reserch Institute, 1996; Mrfo, 1997). The bility of penut to fix tmospheric nitrogen in the soil lso improves the fertility of the otherwise poor soils chrcteristic of northern Ghn (Kleem, 1990). Despite its importnce, penut frmers in northern Ghn continue to not fully recognize the negtive impct of number of production constrints mong which re the problems of rthropod pests nd diseses. In preliminry survey of penut production in the Northern Region, 45 65% of respondent frmers sid rthropod pests negtively impct penut production (Slifu, 1991). Penut frmers cited subterrnen dmge nd spoilge in storge s primry constrints to high nd stble yields. Pst studies hve shown tht more thn 350 species of insects dmge penut in different prts of the world (Stlker nd Cmpbell, 1983). The economic importnce of the soil pests, termites (Isopter: Termitide), millipedes (Myripod: Odontopygide) nd white grubs (Coleopter: Scrbeide) hs been well documented in prts of Afric (Wightmn et l., 1990; Umeh et l., 1999, 2001). These pests penetrte nd feed on roots, developing pods, nd kernels (Umeh et l., 1999; Wightmn et l., 1990). This feeding behviour lso predisposes pods to ttck by disese pthogens such s the fltoxin-producing fungus, Aspergillus flvus (Link) (Lynch et l., 1990; Wliyr et l., 1994; Wightmn et l., 1990). Yield losses of up to 70% hve been ttributed to termites lone in prts of Nigeri (Johnson et l., 1981; Umeh et l., 1999). In plces where soil pests re problem, insecticides Penut Science (2012) 39:

2 114 PEANUT SCIENCE re used for control (Wightmn et l., 1990; Brndenburg nd Herbert, 1991). There is scrce informtion on pest profiles nd sttus on penut in northern Ghn. In ddition, there is no informtion on insecticide control nd how it ffects penut yield. The present studies were conducted to identify key soil rthropod pests of penut, their distribution nd density, nd their effect on penut qulity in northern Ghn. The effects of insecticide tretments on control of these pests nd on yield were lso ssessed. Mterils nd Methods Survey of soil rthropod pests. Surveys of soil rthropod pests were crried out on frmers fields from August to October in the Northern, Upper Est nd Upper West Regions of Ghn during the cropping sesons of The survey re lies between ltitudes 8u 009s nd 11u 29 N nd longitudes 0u 309 E nd 2u 59 W. This re hs monomodl rinfll pttern tht rnges between 600 nd 1253 mm per nnum nd men nnul temperture between 26 C nd 29 C (Ksei 1990). During the surveys frmers were either hrvesting or prepring to hrvest their penut crops. An verge of seven mjor penut growing villges in the Northern Region nd five ech in the Upper Est nd Upper West Regions were rndomly selected ech yer nd three to four frms per villge were selected for smpling. Smpled frms were t lest 2 kilometers prt. A totl of 53 frms (one field per frm) ech in 2003 nd 2004, nd 67 frms in 2005 were surveyed cross the three regions. Five plnts were rndomly selected nd dug out with bout 60 cm 3 of soil round the pod nd root zone from 5 3 5m mrked section in ech frm. To ccount for ny sptil vribility, ten plnt smples were tken on frms with less uniformity in plnt rchitecture, or frms lrger thn two h. The plnts were lifted with the soil using hnd-hoe nd the different rthropods in the soil nd on the roots nd pods were sorted in situ, counted nd ppropritely recorded. The numbers of plnts with one or more soil rthropods present were lso recorded. The percentge of pods with rthropod penetrtion holes or hull scrifiction ws determined from the smpled plnts. Bckground informtion on frms. Prior to smpling ech frm, checklist ws used to obtin informtion from frmers on penut cultiror plnted, time of plnting, cropping sequence, nd whether the field ws solely penut or interplnted with other crops. The soil type t the frm, weed mngement prctices, frmer s knowledge of soil rthropod pests nd control prctices pplied, if ny, were lso recorded. Assessment of yield loss. Experiments were conducted t Nynkpl (9u 429 N ltitude, nd 0u 929 W longitude, nd 184 m ltitude) nd Bgurugu (9u 539 N ltitude, nd 0u 439 W longitude, nd 168 m ltitude) from The loctions re mjor penut growing res in the Northern Region. Soil type t both loctions ws grvelly-sndy lom. Penut cultivr JL 24 which is susceptible to soil rthropod pests ws used. Tretments included chlorpyrifos (Dursbn 4E, Dow AgroSciences, Indinpolis, IN, USA) or crbofurn (Furdn 3G, FMC Corp., Phildelphi, PA, USA) pplied t the pproprite rtes t plnting by hnd infurrow or pplied by hnd long ech row over the vines t pegging (50 dys fter plnting) (Lynch et l., 1991). A non-treted control nd one with insecticide tretments t both plnting nd pegging were included. Chlorpyrifos nd crbofurn were pplied t the rtes of 2.2 kg i h 21 nd 1.0 kg i h 21, respectively. At Nynkpl, pplictions t plnting were mde on 8 June in 2005 nd 31 My in 2006; pplictions t pegging were mde on 28 July nd 20 July in 2005 nd 2006, respectively. At Bgurugu, t-plnting pplictions were mde on 14 June in 2005 nd 8 June in 2006 wheres t-pegging pplictions were mde on 3 August in 2005 nd 28 July in The tretments were rrnged in split-plot design nd replicted four times. Insecticide tretment constituted the min plot effect, nd ppliction timing the subplot effect. Ech sub-plot (10 m 2 ) consisted of four 5 m long rows spced 0.5 m prt. Plnts within rows were spced 0.2 m. There ws 1 m spcing between plots in min plots nd 2 m between min plots. The experiments t Nynkpl were plnted on 8 June 2005 nd 31 My 2006 wheres those t Bgurugu were plnted on 14 June 2005 nd 8 June Five rndomly selected plnts nd dhering soil were dug out s previously described within the outer two rows of ech plot for soil rthropod pests t hrvest. Arthropods in the soil nd on the plnt smples were sorted in situ, counted nd recorded. Dt on pod hull scrifiction nd penetrtion, nd yield in treted nd untreted plots were lso recorded. The two middle rows of ech plot were hrvested to determine yield. Sttisticl nlyses. All dt were subjected to nlysis of vrince nd where F-vlues were significnt t P # 0.05 mens were seprted using Fisher s protected lest significnt difference (LSD) test (SAS Institute, 1998). Dt on rthropod count were trnsformed to log 10 (X + 1) wheres dt on

3 SOIL ARTHROPOD PESTS AND YIELD LOSS IN NORTHERN GHANA 115 Tble 1. Men 6 SE numbers of soil rthropod pests nd percent infested plnts, scrified nd penetrted pods by pests in northern Ghn during 2003 riny seson. No. /5 plnts % Region Millipede White grub Wireworm Termite Infested plnts Scrified pods Penetrted pods Northern b Upper Est b Upper West b b b b F-vlue P. F Vlues re mens of 23, 16 nd 14 frms smpled in Northern, Upper Est nd Upper West Regions, respectively. Mens 6 SE in column followed by the sme letter re not significntly different t P # percentge dmge were subjected to squre root or rcsine squre root trnsformtion to normlize vrinces before nlyses (Gomez nd Gomez, 1984). Chi-squred nlyses were used to test the reltionships between the cropping systems of the three regions. Pod yield losses were computed by subtrcting yields of untreted plots from those of insecticide-treted plots nd the difference clculted s percentge. Correltion nlyses were used to ssess the reltionships between pod yield nd rthropod densities, percentge of pods scrified, nd percentge of pods penetrted. Results Bckground informtion on frms: Across the regions surveyed, twenty seven percent of frmers (n 5 173) plnted penut t the onset of the rins in April while 32% plnted in My. The mjority (41%) of the frmers, however, plnted penut when the rins stbilized in June (dt not presented). Improved penut cultirors with bunch or erect morphologicl chrcteristics such s Mnipintr were cultivted by 96.4% of the frmers while the remining 3.6% sid they grew locllyderived cultirors such s Bugl (dt not presented). Generlly, cerels such s corn (Ze mys L.) preceded penut but penut preceding penut ws lso prcticed. Intercropping penuts with cerels (nd occsionlly with other legumes such s Bmbr groundnuts, Vondze subterrne) ws common nd more in the Upper Est nd Upper West Regions (65.7 nd 45.5% of frmers, respectively) thn in the Northern Region (31.1%) (x , df 5 2, P ). The mjority of the frmers in the Northern Region generlly prcticed penut monoculture on lrge trcts of lnd. Penut frms in this region rnged from h with men of 1.7 hectres s opposed to rnge of hectres with men of 0.6 h in the Upper Regions (dt not presented). The surfce soil texture of penut fields ws generlly sndy-silty lom or grvelly-sndy lom. Hoeing ws the dominnt weed control method nd ws prcticed by 91% of frmers. Fifty-two percent of frmers weeded their fields only once t 3 5 weeks fter plnting (WAP), 36 percent weeded twice t 2 3 nd 5 6 WAP while only 2% weeded three times (dt not presented). About 65% of the frmers smpled cross the regions hd generl understnding of the soil rthropods ttcking their penut crop nd the dmge cused but none of them prcticed ny control (dt not presented). Survey of soil rthropod pests: The survey reveled tht termites (Microtermes sp. nd Odontotermes sp), millipedes (Peridontopyge sp.), white grubs (Schyzonich fricn Lp.) nd wireworms (Elterid lrve) were the min soil pests infesting penut in the field (tbles 1 3). Termites nd Tble 2. Men 6 SE numbers of soil rthropod pests nd percent infested plnts, scrified nd penetrted pods by pests in northern Ghn during 2004 riny seson. No. /5 plnts % Region Millipede White grub Wireworm Termite Infested plnts Scrified pods Penetrted pods Northern Upper Est b b b b Upper West b b b F-vlue P. F Vlues re mens of 20, 19, nd 14 frms smpled from Northern, Upper Est, nd Upper West Regions, respectively. Mens 6 SE in column followed by the sme letter re not significntly different t P # 0.05.

4 116 PEANUT SCIENCE Tble 3. Men 6SE numbers of soil rthropod pests nd percent infested plnts, scrified nd penetrted pods by pests in northern Ghn during 2005 riny seson. No. /5 plnts % Region Millipede White grub Wireworm Termite Infested plnts Scrified pods Penetrted pods Northern Upper Est b Upper West F-vlue P. F Vlues re mens of 26, 22, nd 19 frms smpled from Northern, Upper Est, nd Upper West Regions, respectively. Mens 6 SE in column followed by the sme letter re not significntly different t P # millipedes were the most bundnt while wireworms were lest in occurrence in ll three yers nd regions of the study. Other insects with infrequent occurrence included mely bugs (Homopter:Pseudoccoccide) nd red nts (Hymenopter:Formicide) tht were observed on penut pods in three fields only in the Northern Region (dt not presented). In 2003, significntly higher millipede densities were recorded in Upper Est Region thn in Upper West Region (tble 1). However, millipede densities in Upper Est Region did not differ from those of Northern Region. Densities of white grubs were higher in Northern nd Upper Est Regions thn in Upper West Region. Wireworm nd termite densities did not differ significntly mong the regions. Significntly higher percentges of plnts were infested in the Northern nd Upper Est Regions thn in the Upper West Region. Pod hull scrifiction did not differ mong the regions, but significntly higher percentge of pods hd rthropod penetrtion holes in Northern Region thn in Upper West Region. In 2004, higher millipede nd wireworm densities were recorded in Northern Region compred with the other regions (tble 2). The densities of the other pests did not differ significntly mong the regions. A higher percentge of plnts were infested in the Northern Region thn in either Upper Est or Upper West Regions. A significntly higher percentge of pods were scrified in Northern nd Upper West Regions thn in Upper Est Region. However, percentge of pods penetrted did not differ mong the regions. In 2005, soil rthropod pest densities, percentge of plnts infested nd percentge of pods penetrted were similr in ll three regions (tble 3). However, percentges of pods scrified were significntly higher in Northern nd Upper West Regions thn in Upper Est Region. Nynkpl. The insecticides, chlorpyrifos nd crbofurn, did not differ significntly in their effects on soil pest densities, pod dmge nd yield in either yer of the study. Also there were no significnt interctions of insecticide nd timing ppliction with reference to the prmeters tested, but tretment ppliction timing did show significnt effects (tble 4). The effect of insecticide ppliction t different penut growth stges on densities of soil pests, penut pod dmge nd yield were very similr for 2005 nd 2006, verged cross insecticides (tble 4). In both yers, millipede densities were lower in treted plots compred with untreted control plots. Millipede densities were lowest nd similr when plots were treted t pegging or t both plnting nd pegging. However, tretment t pegging in 2005 or t both plnting nd pegging in 2006 did not significntly lower millipede densities compred to tretment t plnting. Wireworms were not recorded in 2005, but significntly higher densities were recorded in the untreted control thn in treted plots in Except for plots treted t plnting in 2005, insecticide tretment lso significntly lowered white grub densities compred with untreted control in both 2005 nd Termite densities were not significntly lowered by insecticide tretments compred with untreted control in However, in 2006 termite densities were significntly reduced in treted reltive to untreted control plots. These results demonstrte tht insecticides produce n overll reduction in ll pest rthropods so there is n overll cumultive benefit even if individul species re present in subeconomic levels. In 2005, percentge of pods scrified ws significntly lower when plots were treted t pegging or t both plnting nd pegging when compred with untreted plots or tretment t plnting. Pod scrifiction ws significntly reduced in ll treted plots compred with untreted plots in 2006 (tble 4). For this yer, percentge scrified pod dmge ws lowest when plots were treted t plnting or t both plnting nd pegging. Percentge of pods tht were penetrted by soil pests ws significntly lower in treted plots compred with untreted controls in both 2005

5 SOIL ARTHROPOD PESTS AND YIELD LOSS IN NORTHERN GHANA 117 Tble 4. Effect of insecticide tretment on soil rthropod densities, percentge scrified pods, percentge penetrted pods, nd pod yield of penut t Nynkpl in northern Ghn during 2005 nd 2006 growing sesons. Tretment timing No, of rthropods/5 plnt stnds Millipede Wireworm White grub Termite Scrified Pods (%) Penetrtedpods(%) PodYield (kg/h) Yield loss(%) 2005 Untreted b 33.7 Plnting 1.9 b b b Pegging 1.3 bc b b 5.4 bc Plnting & pegging 0.8 c b b 4.5 c F-vlue P. F, , , Untreted b 22.6 Plnting 0.9 b 0.0 b 0.5 b 0.0 b 5.1 bc 6.8 c Pegging 0.1 c 0.0 b 0.3 b 0.0 b 6.6 b 10.9 b Plnting & pegging 0.3 bc 0.0 b 0.1 b 0.0 b 3.0 c 5.5 c F-vlue P. F ,0.0001, In-furrow pplictions of chlorpyrifos t 2.2 kg.i. h 21 or crbofurn t 1.0 kg.i h 21. Applictions t plnting were mde on 8 June in 2005 nd 31 My in 2006; pplictions t pegging were mde by hnd over the row on 28 July in 2005 nd 20 July in Chlorpyrifos nd crbofurn dt combined bsed on lck of interction effect. Mens within yers in ech column followed by the sme letter re not significntly different t P # 0.05 (Fisher s LSD test). nd In 2005, the percentge of pods penetrted ws lowest in plots tht were treted t both plnting nd pegging. In 2006, the percentge of pods penetrted ws lowest when plots were treted either t plnting or t both plnting nd pegging. Pod yield ws significntly incresed in treted compred with untreted plots in both 2005 nd 2006 (tble 4), nd this increse ws not influenced by timing of insecticide tretment. In 2005, percent yield losses in untreted plots were 35.6, 31.6 nd 33.7 when compred to plots treted t plnting, pegging, or t both plnting nd pegging, respectively. Yield losses in 2006 were 25.1, 25.7 nd 22.6% reltive to plnting, pegging, nd plnting plus pegging tretment, respectively. In 2005, pod yield ws negtively correlted to the percentge of penetrted pods (r , P ) nd to some extent to millipede densities (r , P ). In 2006, pod yield per hectre ws negtively correlted with totl pest densities (r 5 244, P ), percentge scrified pods (r , P ) nd percentge penetrted pods (r , P ). Among the pests in test plots, pod yield ws most correlted with millipede (r , P ) nd termite (r , P ) popultions. Bgurugu. As in Nynkpl, the effects of insecticide type s well s insecticide by ppliction timing interctions were not significnt for the prmeters tested both for 2005 nd 2006 (tble 5). However, ppliction timing showed significnt effects. Averged cross insecticides, the effect of insecticide ppliction t the different penut growth stges on the prmeters tested were similr for 2005 nd In both yers, except t plnting in 2005, millipede densities were lower in treted thn in untreted plots. Wireworm densities were low in both yers, nd there were no significnt differences due to tretments t the different growth stges. White grub densities did not differ mong the tretments in However, in 2006, white grub densities were significntly lower in treted thn in untreted plots. Termite densities were not significntly lowered by insecticide tretment t the different growth stges compred with control in However, in 2006, termite densities were significntly lower in treted plots. For both 2005 nd 2006, percentge of pods scrified ws significntly lower in treted thn in untreted plots (tble 5). Pod scrifiction ws lowest in plots tht were treted t pegging or t both plnting nd pegging in Also, percentge of pods penetrted ws lower in treted thn in untreted plots in both 2005 nd Pod penetrtion dmge in 2005 ws lowest in plots tht were treted t both plnting nd pegging nd in 2006 it ws lowest in plots treted t plnting or t both plnting nd pegging. Pod yield incresed in treted plots over the untreted control in 2005, but not in 2006 (tble 5). In 2005, yield ws highest nd similr in plots treted t pegging nd t both plnting nd pegging. Yield losses in untreted plots were 26.6,

6 118 PEANUT SCIENCE Tble 5. Effect of insecticide tretment on soil rthropod densities, percent scrified pods, percent penetrted pods, nd pod yield of penut t Bgurugu in northern Ghn during 2005 nd 2006 growing sesons. Tretment timing No, of rthropods/5 plnt stnds Millipede Wireworm White grub Termite Scrified Pods (%) Penetrtedpods(%) PodYield (Kg/h) Yield loss(%) 2005 Untreted c 38.8 Plnting b 7.6 b 780 b 15.3 Pegging 0.9 b 0, c 6.6 b Plnting & pegging 0.8 b c 4.4 c F-vlue P. F, ,0.0001,0.0001, Untreted Plnting 0.8 b b 8.8 b 10.8 b 5.4 c Pegging 0.5 b b 16.3 b 14.4 b 9.0 b Plnting & pegging 0.4 b b 25.0 b 10.9 b 6.4 c F-vlue P. F, , In-furrow pplictions of chlorpyrifos t 2.2 kg.i. h 21 or crbofurn t 1.0 kg.i h 21. Applictions t plnting were mde on 14 June in 2005 nd 8 June in 2006; pplictions t pegging were mde by hnd over the row on 3 August in 2005 nd 28 July in Chlorpyrifos nd crbofurn dt combined bsed on lck of interction effect. Mens in yer nd for ech prmeter in column followed by the sme letter re not significntly different t P # 0.05 (Fisher s LSD test) nd 38.8% reltive to plots treted t plnting, pegging or t both plnting nd pegging, respectively. There were significnt negtive correltions between pod yield nd millipede bundnce (r , P 5,0.0001),white grub bundnce (r , P ), percentge scrified pods (r , P ), nd percentge penetrted pods (r , P ) in No significnt correltions were detected mong these prmeters in Discussion Results from this study showed tht termites, millipedes, white grubs nd wireworms were the mjor soil rthropod pests of penut in northern Ghn (Abuduli et l., 2007) s lso reported for other prts of Afric (Wightmn et l., 1990; Umeh et l., 1999; Owusu-Akyw et l., 2005). Termites were the most bundnt soil pests surveyed in both yers, nd ccounted for.70% of ll soil pests recorded from soil nd plnt smples. Millipedes were the next most bundnt pests followed by white grubs. Wireworms were lest in bundnce, which lso grees with the findings by Umeh et l., (1999, 2001). The ctivities of these pests negtively ffected the qulity of hrvested penut s shown by the high percentges of infested plnts, scrified nd penetrted pods. The pests including white grubs, millipedes nd wireworms my lso hve reduced plnt stnd nd yield by severing the min stem t soil level (Johnson et l., 1981; Wightmn et l., 1990; Lynch et l., 1991). In ddition, their feeding ctivities increse the risk of fltoxin contmintion in penut (Wightmn et l., 1990). The high pest densities nd pod dmge by scrifiction nd penetrtion in the Northern Region compred to the other regions ws likely due to concentrtion of resources becuse of the gretest production in the Northern Region (SRID, 2004). The high incidence of penut monoculture in this region my lso enhnce rthropod ctivities compred with the mixed culturl systems (Andow, 1991; Tonhsc nd Byrne, 1994; Bnks nd Ekbom, 1999) such s those of the Upper Regions. The reduction in the densities of ll the four soil pests due to insecticide tretment resulted in the reduction of the numbers of pods dmged through scrifiction nd penetrtion leding to incresed pod yields. Generlly, tretment t plnting or pegging ws sufficient for lowering pest densities nd pod dmge to increse yield. These results re in greement with the findings of Brndenburg nd Herbert (1991), Lynch et l. (1991), Anith et l. (2005) nd Owusu-Akyw et l. (2005). Wightmn et l. (1990), however, reported from field tests crried out in Mlwi tht insecticide tretments did not reduce densities of millipedes. Since millipedes re not insects their susceptibility to these products my be less thn tht of the other rthropods. There ws no significnt difference between crbofurn nd chlorpyrifos on the prmeters tested, indicting tht the two insecticides hd similr efficcy on penut pests. Numerous studies

7 SOIL ARTHROPOD PESTS AND YIELD LOSS IN NORTHERN GHANA 119 lso hve shown tht both chemicls re efficcious ginst soil pests of penut (Wightmn et l., 1990; Anith et l., 2005; Owusu-Akyw et l., 2005). Owusu-Akyw et l., (2005), however, reported higher efficcy for chlorpyrifos thn crbofurn ginst soil pests of penut in southern Ghn. Although crbofurn is no longer lbeled for use by frmers becuse of environmentl concerns (Pimentel et l., 1992), it ws included in the present tests for yield loss ssessment becuse of its known effectiveness ginst soil pests. The bsence of ny significnt difference between crbofurn nd chlorpyrifos confirmed the efficcy of chlorpyrifos which is currently used for pest control in penut (Brndenburg nd Herbert, 1991). In generl, correltion nlyses indicted tht insecticide tretment hd positive effect on penut pod yield by reducing pest densities nd pod dmge. Pod penetrtion ws considered good indictor of the degree of plnt dmge nd thus yield loss in prts of Afric (Wightmn et l., 1990). Surfce scrifiction of pods probbly wekened pods for esy penetrtion by rthropods (Abuduli et l., 2007). Penut pod yield loss in untreted plots rnged between 23 nd 36% in Nynkpl nd between 26 nd 39% in Bgurugu. Yields were generlly lower t Bgurugu thn t Nynkpl, which my be ttributed to more consistent rinfll tht my hve influenced pest densities nd crop performnce (Pdmlth et l., 2006). In conclusion, the results of these studies demonstrted tht termites, millipedes, white grubs nd wireworms re the mjor soil rthropods pests of penut in northern Ghn. These rthropods impct negtively on penut qulity nd yield. Insecticide protection either t plnting or pegging lowered pest densities nd resulted in incresed pod yield, nd therefore could be useful mngement prctice for penut soil pests. At this time, however, insecticide control for penut pests is currently not prcticed by frmers in Ghn due lrgely to the high price of these products(wightmn et l., 1990). This demonstrtes the need for further reserch on control options tht re less expensive nd cn be redily obtined by frmers. Acknowledgements We thnk Frederick Anmn nd Misbw Hrun for ssistnce in the field work. We re especilly grteful to the frmers tht cooperted with us during the surveys. Finncil support provided by the United Sttes Agency for Interntionl Development under the Penut Collbortive Reserch nd Support Progrm grnt LAG-G is gretly pprecited. Literture Cited Abuduli, M., I.K. Dzomeku, A.B. Slifu, S.K. Nutsugh, R.L. Brndenburg, nd D. Jordn Influence of culturl prctices on soil rthropods, lef spot, pod dmge, nd yield of penut in northern Ghn. Penut Sci. 34: Andow, D Vegettionl diversity nd rthropod popultion response. Ann. Rev. Entomol. 36: Anith, V., J. Wightmn, nd D.J. Rogers Mngement of white grubs (Coleopter: Scrbeide) on groundnut in southern Indi. Int l J. Pest Mnge. 51: Bnks, J.E. nd B. Ekbom Modelling herbivore movement nd coloniztion: pest mngement potentil of intercropping nd trp cropping. Agric. Forest Entomol. 1: Brndenburg, R.L. nd D.A. Herbert, Jr Effect of timing on prophylctic tretments for southern corn rootworm (Coleopter: Chrysomelide) in penut. J. Econ. Entomol. 84: Johnson, R.A., R.W. Lmb, nd T.G. Wood Termite dmge nd crop loss studies in Nigeri survey of dmge to groundnuts. Trop. Pest Mnge. 27: Kleem, F Assessment of nitrogen fixtion by legumes nd their reltive contribution to succeeding mize crop in the svnnh zone of Ghn. In: Proceedings of the second workshop on improving frming systems in the interior svnn zone of Ghn, th April, 1990, H. Rudt, H. Mercer-Qurshie, J. von Brgen, K.O. Mrfo, A.B. Slifu, A.L. Nymekye, J.J. Afukw, R.C. Dekuku, nd P.Y.K. Sllh (eds.), Nynkpl Agriculturl Experiment Sttion, Nynkpl, Ghn. pp Ksei, C.N A synopsis on the climte of the North of Ghn. In: Proceedings of the second workshop on improving frming systems in the interior svnn zone of Ghn, th April, 1990, H. Rudt, H. Mercer-Qurshie, J. von Brgen, K.O. Mrfo, A.B. Slifu, A.L. Nymekye, J.J. Afukw, R.C. Dekuku, nd P.Y.K. Sllh (eds.), Nynkpl Agriculturl Experiment Sttion, Nynkpl, Ghn. pp Lynch, R.E., A.P. Ouedrogo, nd S.A. Some Effect of hrvest dte nd termite-resistnt vrieties on termite nd millipede dmge to groundnut in Burkin Fso. In: Summry proceedings of the first ICRISAT regionl groundnut meeting for West Afric, September 1988, ICRISAT Shelin Centre, Nimey, Niger, pp Lynch, R.E., I.O. Dicko, S.A. Some, nd A.P. Ouedrogo Effect of hrvest dte on termite dmge, yield nd fltoxin contmintion in groundnut in Burkin Fso. IAN 10: Mrfo, K.O The performnce nd ssocition mong some importnt penut yield trits in northern Ghn. In: Proceedings of the 3 rd Workshop on improving frming systems in the interior Svnn zone of Ghn, th April, 1993, H. Mercer-Qurshie, K.O. Mrfo, A.S. Lngyintuo, nd R.K. Owusu (eds.), Nynkpl Agriculturl Experiment Sttion, Tmle, Ghn. pp Nturl Reserch Institute. 1996, Groundnuts. Pest control series. Hobbs the printers Ltd, Totton, Hmpshire. Owusu-Akyw, M., J.V.K. Afun, M.B. Mochih, J. Adu-Mensh, E. Moses, G. Bolfrey-Arku, K. Osei, S. Osei-Yeboh, A.A. Dnkyi, I. Adm, R.L. Brndenburg, nd D.L. Jordn Survey nd mngement of soil rthropods in penut (Archis hypoge L) in southern Ghn, West Afric. Penut Sci. 32: Pdmlth, Y., S.R. Reddy, nd T.Y. Reddy The reltionship between wether prmeters during developmentl phse nd fruit ttributes nd yield of penut. Penut Sci. 33: Pimentel, D., H. Acquy, H. Biltonen, P. Rice, M. Silv, J. Nelson, V. Lipner, S. Giordno, A. Horowitz, nd M. D Amore Environmentl nd economic costs of pesticide use. Bioscience. 42: Slifu, A.B Nynkpl Agriculturl Experimentl Sttion, Crops Reserch Institute, Annul Report for SAS Institute. 1998, SAS User guide sttistics, 8th edn. SAS Institute Inc., Cry, NC.

8 120 PEANUT SCIENCE SRID, Production of mjor crops in Ghn, Sttistics, Reserch nd Informtion Directorte (SRID), Ministry of Food nd Agriculture, Ghn. Stlker, H.T. nd W.V. Cmpbell Resistnce of wild species of penut to n insect complex. Penut Sci. 10: Tonhsc, A. Jr. nd D.A. Byrne The effect of crop diversifiction on herbivorous insects: met-nlysis pproch. Ecol. Entomol. 19: Umeh, V.C., F. Wliyr, S. Trore, nd E. Egwurube Soil pests of groundnut in West Afric species diversity, dmge nd estimtion of yield losses. Insect Sci. Applic. 19: Umeh, V.C., O. Yuom, nd F. Wliyr Soil pests of penut in sub-shrn Afric A Review. Insect Sci. Applic. 21: Wliyr, F., A. B, H. Hmm, S. Bonkoungou, nd J.P. Bosc Sources of resistnce to Aspergillus flvus nd fltoxin contmintion in groundnut genotypes in West Afric. Plnt Dis. 78: Wightmn, J.A., K.M. Dick, G.V. Rng Rw, T.G. Shnower, nd C.G. Gold Pests of groundnut in the semi-rid tropics. In: Insect pests of legumes, S.R. Singh (ed.), Longmn nd Sons Ltd, New York. pp