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1 Biologicl 5 (9) 5 57 Contents lists ville t ScienceDirect Biologicl journl homepge: Monitored releses of Rhinoncomimus ltipes (Coleopter: Curculionide), iologicl control gent of mile--minute weed (Persicri perfolit), Judith Hough-Goldstein,, Mrk. Myer, Wyne Hudson, George Roins, Ptrici Morrison c, Richrd Rerdon d Deprtment of Entomology & Wildlife Ecology, University of Delwre, Newrk, DE 97-, US Phillip lmpi Beneficil Insect Lortory, N.J. Dept. gric., Trenton, NJ 5, US c Ohio River Islnds Ntionl Wildlife Refuge, Willimstown, WV 7, US d USD Forest Helth Technology Enterprise Tem, Morgntown, WV 55, US rticle info strct rticle history: Received pril 9 ccepted ugust 9 ville online 9 ugust 9 Keywords: Persicri perfolit Polygonum perfolitum Rhinoncomimus ltipes Mile--minute weed Weed iologicl control gent estlishment Monitoring Mile--minute weed, Persicri perfolit (L.) H. Gross, is n invsive nnul vine of sin origin tht hs developed extensive monocultures, especilly in distured open res in the Mid-tlntic region of the United Sttes. host-specific sin weevil, Rhinoncomimus ltipes Korotyev, ws pproved for relese in North meric in, nd weevils hve een rered t the New Jersey Deprtment of griculture Beneficil Insect Lortory since then. By the end of 7 more thn 5, weevils hd een rered nd relesed, mostly in New Jersey, ut lso in Delwre, Mrylnd, Pennsylvni, nd West Virgini. The eetles estlished t out of 5 sites (9.9%) where they were relesed etween nd 7, with successful releses consisting of s few s weevils. Weevils were recorded t dditionl non-relese sites in New Jersey, where they hd dispersed t n verge rte of. km/yer. Stndrdized monitoring of fixed qudrts ws conducted in pired relese nd control sites t eight loctions. Significnt differences in mile--minute weed popultions in the presence nd sence of weevils were found t three loctions, with reduction in spring densities to 5% or less of wht they hd een t the strt within yers t relese sites, while weed densities t control sites were lrgely unchnged. Mile-minute weed popultions t fourth site were similrly reduced t the relese site, ut without control dt for comprison due to rpid coloniztion of the pired control site. t the other four loctions, ll on islnds, mile--minute weed popultions were reduced t oth relese nd control sites without lrge weevil popultions developing, pprently due to environmentl conditions such s lte frost nd extreme drought. Ó 9 Elsevier Inc. ll rights reserved.. Introduction Mile--minute weed, Persicri perfolit (L.) H. Gross (Polygoncee; formerly Polygonum perfolitum L.) is n nnul vine ccidentlly introduced from si to nursery ner York, Pennsylvni, US, in the 9s. It infests nturl res in vriety of hitts in its imported rnge nd hs developed extensive monocultures in some res (Hough-Goldstein et l.,,; McCormick nd Hrtwig, 995; Mountin, 99; Wu et l., ). iologicl control progrm for the weed ws initited y the USD Forest Service in 99 (Wu et l., ). The most promising cndidte gent, Rhinoncomimus ltipes Korotyev (Coleopter: Curculionide), ws tested on plnt species in Chin nd in qurntine in Delwre nd found to e extremely host specific (Colpetzer Corresponding uthor. Fx: + 9. E-mil ddress: jhough@udel.edu (J. Hough-Goldstein). et l., ; Ding et l., ; Price et l., ). This weevil ws pproved y USD-PHIS for relese in the United Sttes in. Rhinoncomimus ltipes lys its eggs on leves, stems, nd uds of P. perfolit. Lrve feed internlly in the stems, nd pupte in the soil, producing three to four overlpping genertions ech yer in the Mid-tlntic region (Lke, 7). Weevils re ctive from erly spring, s soon s mile--minute seedlings pper, until fll, when the vines die with the first hrd frost. Simulted dmge tht mimicked R. ltipes feeding cused plnt mortlity when pplied to smll P. perfolit plnts, nd reduced iomss nd seed production when pplied to lrger plnts (Colpetzer et l., ), suggesting tht R. ltipes could hve sustntil impct on P. perfolit popultions. Susequent tests in field cges showed tht R. ltipes feeding on P. perfolit reduces plnt growth nd delys seed production, nd cn kill plnts when competing vegettion is present (Hough-Goldstein et l., ). The weevil hs een rered t the New Jersey Deprtment of griculture Phillip lmpi Beneficil Insect Lortory in Trenton, 9-9/$ - see front mtter Ó 9 Elsevier Inc. ll rights reserved. doi:./j.iocontrol.9..5

2 J. Hough-Goldstein et l. / Biologicl 5 (9) New Jersey, since fll of. By the end of 7 more thn 5, weevils hd een rered nd relesed, mostly in New Jersey, ut lso t sites in Delwre, Mrylnd, Pennsylvni, nd West Virgini. stndrdized monitoring protocol ws used to trck weevil nd plnt popultions t some, ut not ll, relese sites. Here we report on () ll sites where R. ltipes were relesed etween nd 7, noting where the weevil overwintered nd estlished popultions; nd () weevil popultion growth nd impct on the mile--minute weed popultion in selected sites where stndrdized monitoring hs een conducted for t lest yers.. Mterils nd methods.. Insects nd sites In July, smll field releses in Delwre nd New Jersey were conducted using R. ltipes rered in qurntine t the USD-griculturl Reserch Service lortory in Newrk, Delwre, plus dditionl insects collected nd sent from Chin in nd held in qurntine efore relese to ssure positive identifiction nd sence of pthogens, prsitoids, or other contminnts. ll weevils were originlly collected from P. perfolit plnts t two sites in Hunn Province, Chin (Leifeng, N, 5 E nd Tongxin, N, 57 E). dditionl insects from the mixed l-rered nd field-collected group were used to initite mss rering t the Phillip lmpi Beneficil Insect Lortory, where insects were rered on potted P. perfolit plnts under fluorescent grow lights (Hough-Goldstein et l., ). ll susequent releses used weevils rered t this fcility, except for few in southestern Pennsylvni in 5, which used comintion of weevils rered in University of Delwre greenhouse nd weevils rered t the Phillip lmpi Lortory, ll from the sme initil R. ltipes stock. For ll releses, weevils were rought to the field in 7-ml wx-lined hot everge cups (Sweethert Cup Compny, Chicgo, IL) with holes cut in ech end. Nylon mesh ws secured over the holes nd plstic Petri dish contining sponge moistened with honey nd wter ws tped to the ottom of the cups. Excelsior wood shvings (Knud Nielsen Compny, Inc., Evergreen, L) were plced in the cups to give the weevils dditionl resting sites. For sttes other thn New Jersey, weevils were shipped overnight in these cups pcked in styrofom shipping continers long with frozen cold pck, nd were relesed s soon s possile following delivery. Upon relese, the excelsior nd ny weevils on it were removed from the cup nd plced on mile--minute weed folige, nd remining weevils were either shken or rushed onto folige or llowed to wlk out on their own. Weevils were relesed t 5 sites in New Jersey nd sites totl in Delwre, Mrylnd, Pennsylvni, nd West Virgini etween nd 7 (Fig. ), with releses occurring etween lte pril nd mid-octoer ech yer. In some cses multiple releses were conducted t single site over the course of the summer. The verge size of releses in New Jersey ws ± 9 (men ± SEM) weevils, with rnge of per site, not including one site in the Supwn Medows Ntionl Wildlife Refuge where the New Jersey lortory hd een contrcted to relese more thn 5, weevils etween June nd Septemer. The verge size of releses in other sttes ws 79 ± weevils, with rnge of 5 totl per site. Estlishment ws ssessed s of... Monitored sites Monitoring ws conducted t pired relese nd control sites t two loctions in New Jersey (designted NJ- nd NJ-), two loctions in Delwre (DE- nd DE-), one loction in Mrylnd (MD- ), nd three loctions in West Virgini (WV-, WV-, nd WV-), using stndrdized monitoring protocol designed to lnce ese of implementtion with collection of useful plnt nd insect popultion dt (Blossey nd Skinner, ). For ech loction, two sites with similr vegettion nd mile--minute weed popultions, ut s fr wy from ech other s possile within the sme generl re (5 m ws suggested), were rndomly ssigned s either the relese or the non-relese (control) site. Dtes nd numers Fig.. Sites where Rhinoncomimus ltipes were relesed, 7. Closed circles indicte monitored sites.

3 5 J. Hough-Goldstein et l. / Biologicl 5 (9) 5 57 of weevils relesed, nd distnces etween relese nd control sites for monitored sites re shown in Tle, nd loctions re shown in Fig.. t ech relese nd control site, ten -m y.5-m qudrts, pproximtely m prt, with mple mile--minute weed popultions were locted nd mrked t ll four corners with pieces of PVC conduit pipe. The qudrts were either locted long -mlong trnsects for liner mile--minute weed ptches (such s long tree lines), or t rndom within mile--minute weed ptch, with qudrt #5, the designted relese point for weevil relese, locted ner the center of the ptch. Sites were visited once ech yer in the spring when mile-minute weed seedlings were pproximtely cm tll, generlly etween lte pril nd mid-my. Numers of dult R. ltipes, numers of mile--minute weed seedlings, percent cover of mile-minute weed, nd presence of R. ltipes feeding dmge ws recorded for ech qudrt. In 5, sites were monitored for weevil numers nd dmge on mile--minute weed terminls (growing tips) surrounding the relese site ech week following the spring smple. Beginning in, ll qudrts were smpled once ech month following the spring seedling counts (or first weevil relese) until plnts senesced. For these smples, sites were surveyed for the following within ech qudrt: numer of dult weevils; percent defolition (noting if there were ny other insects present side from R. ltipes tht could hve produced the defolition, such s Jpnese eetles); nd percent mile--minute weed cover (eginning in lte summer of in Delwre nd in 7 t other sites). t ech smple dte, surveyors were lso sked to identify the most undnt other plnts in the qudrts. In New Jersey, the NJ- relese site ws in the ott s Medow Wildlife Mngement re nd the control site ws locted. km wy in n isolted overgrown field surrounded y t lest. km uffer of forest on ll sides. ll other control sites were locted etween 5 nd 5 m from the pired relese site (Tle ). Numers of weevils relesed vried from low of t ech of the DE sites (in ) nd t WV- nd WV- (in 5) to high of 97 t NJ- (relesed etween pril nd Septemer, 5; Tle ). t site DE-, in ddition to the weevil relese,. m field cge ws plced over mile--minute weed plnts, with 5 weevils dded in ugust of ; weevils reproduced in the cge, which ws removed in spring of when it ws pprent tht open field releses were very successful. Fewer thn dditionl weevils were relesed t the DE- nd DE- relese sites during the fll of 5 (left over from nery cge experiments). The Mrylnd relese site ws on Grrett Islnd, t the mouth of the Susquehnn River. The three West Virgini releses lso took plce on islnds, t the Ohio River Islnds Ntionl Wildlife Refuge. For dt nlyses, the squre root trnsformtion (squre root [x +.5]) ws pplied to count dt (weevils nd spring seedling counts) nd the rcsin trnsformtion (rcsin of the squre root of the proportion) to percent cover dt, in oth cses to reduce heteroskedsticity of vrinces. Pired relese nd control sites were compred t ech dte with t-tests; in ddition, for the spring smples ech relese nd control site ws compred to itself in different yers, using NOV nd LSD comprisons y yer. Nontrnsformed verges nd stndrd errors re shown in Figures.. Results.. Weevil estlishment nd dispersl s of, dult R. ltipes, their feeding dmge, or oth hd een oserved t out of 5 of the sites where weevils were relesed in New Jersey in through 7, nd t ll sites where they hd een relesed in other sttes. In ddition to res where R. ltipes were relesed, they were recorded t dditionl sites in New Jersey where they hd dispersed on their own, six etween ugust nd Septemer, 7, nd the rest etween June nd Octoer,. These non-relese recoveries in New Jersey occurred etween nd yers following relese t the nerest relese site (verge of. ±. yers [men ± SEM]), nd verged.7 ±.5 km from the nerest relese site. Dividing distnce y yers fter relese for ech non-relese recovery site yields n verge dispersl distnce of. ±.5 km per yer. In southestern Pennsylvni, weevils were found pproximtely m from June 5 relese site in Octoer 5, nd 7 m y ugust (detils in Lke, 7). In West Virgini, y R. ltipes relesed in 5 hd dispersed from the islnds cross the Ohio River to oth minlnds, nd over km up river... Monitored sites ll eight of the pired control sites were colonized y dispersing weevils, two within yer, nd five within yers. The NJ- control site, which ws considerly further wy from its pired relese site thn the others s well s eing isolted y uffer of trees on ll sides, remined pprently weevil-free for yers (Tle ). ssuming the colonizers t ech control site cme from its pired relese site, the weevils tht moved into these sites hd dispersed t rte of 5 5 m per yer for most sites, nd t.5 km per yer for the NJ- site (Tle ). t the NJ- site, spring mile--minute weed densities t the relese nd control site were comprle t the strt of the study, ut y 7 weed densities t the relese site were only out 5% of wht they hd een t the strt, while densities t the control site were lrgely unchnged (Fig. ). Spring seedling counts nd percent cover were significntly lower in the relese thn in the control plots in, 7, nd (Fig. ). Following relese Tle Loction, dte nd numers of weevils relesed t monitored relese sites, distnce to pired control sites, nd dte nd time until weevils were first found in control plots. Site Loction Dtes relesed Numer relesed Distnce to control First weevils in control Time to rech control (yr) NJ- ott s Medow WM / 9/9/5 97. km 7//.5 km NJ- Floodgte Rod 7// 5 m 9/7/ 5 m /7 /9/5 97 DE- White Cly Creek Stte Prk 7/, 7// 5 m /5/ 5 m DE- White Cly Creek Stte Prk 7/, 7// m /5/ 5 m MD- Grrett Islnd // 5 m /5/7 5 m //7 WV- Muskingum Islnd //5 5 m 7//7 5 m WV- Muskingum Islnd //5 5 m 7//7 5 m WV- Nel Islnd // 5 m 7//7 5 m Dispersl rte per yer

4 J. Hough-Goldstein et l. / Biologicl 5 (9) NJ- Spring smples MM seedlings c Relese 5 7 MM % cover c B 5 7 c Fig.. Mile--minute weed seedlings nd percent cover in My, site NJ-. Brs with the sme letter (lower cse for relese, upper-cse for control) re not significntly different from ech other over different yers; pired relese nd control rs ech yer with n sterisk re significntly different from ech other (P.5, NOV nd LSD comprisons conducted on squre root-trnsformed seedling counts nd rcsin-trnsformed percent cover dt; originl mens nd SEMs shown). c B B NJ- Weevils per qudrt 7 Relese of nerly 7 weevils during the summer of 5, sustntil weevil popultion developed t the NJ- relese site y ugust, (Fig. ), nd hevy feeding y these weevils depleted the ville mile--minute weed folige nd ppered to trigger weevil dispersl. Weevil numers remined significntly higher in the relese thn in the control site throughout 7, ut y weevil counts did not differ etween control nd relese sites (Fig. ). Percent cover of mile--minute weed ws significntly lower in the relese thn in the control site throughout 7 ( yers post-relese) nd until ugust (Fig. ). The NJ- site received the second lrgest numer of weevils fter NJ-, with totl of 97 relesed over yers, in nd the rest in 5 (Tle ). Weevils were found t the NJ- control site y ugust, nd monitoring ws susequently discontinued t this site. t the relese site, the spring mile--minute weed popultion declined from more thn 9 seedlings (5% cover) per qudrt in 5 to fewer thn (% cover) in (Fig. 5). Weevil numers were very high t this site, with n verge of more thn per.5-m qudrt counted in ugust of (Fig. ), cusing ovious defolition of the mile--minute weed. By Octoer,, plnts were severely dmged nd numerous weevils were present: more thn weevils were collected in under minute y plcing clipord under the defolited stems t this site nd gently tpping the plnts. Weevil numers declined in monitored qudrts during 7 nd (Fig. ), s the percent cover of P. perfolit in the NJ- relese qudrts declined to 5% or less (Fig. 7). t the DE- relese site, s t NJ-, mile--minute weed popultion densities were comprle in the relese nd control sites in spring of 5, ut y the relese site qudrts verged Fig.. Rhinoncomimus ltipes dults per qudrt, site NJ-. sterisk indictes significnt difference etween relese nd control qudrts (P.5, t-tests conducted on squre root-trnsformed weevil counts; originl mens nd SEMs shown). less thn 5% cover, while seedling numers nd percent cover remined unchnged t the control site (Fig. ). Both seedling counts nd spring percent cover were significntly lower in the relese thn in the control qudrts in nd 7 (Fig. ). By very little mile--minute could e found t the DE- relese site except t the sunny, exposed edges of the ptch ordering mowed field. Summer monitoring t this site ws discontinued in 7 nd due to lck of mile--minute weed in the monitored qudrts. Oservtions in suggested tht the few mile--minute weed plnts tht continued to emerge in the center of this diverse site were hevily defolited y R. ltipes. Numerous weevils nd considerle feeding dmge ws lso oserved on the mile--minute weed plnts present t the edge of the site. By 7 weevils were present t reltively high numers in the DE- control plots (Fig. 9). The DE control plots were only smpled once during the summer of, on ugust. t tht time the men (±SEM) percent cover ws 5. ±.5% t the DE- control site (now with mny weevils present), significntly lower thn percent cover in these qudrts the previous yer ( ugust, 7, 5.5 ±.7%; F, =., P =.5). t the DE- relese site, where weevils were relesed in lte July, mile--minute weed seedling numers were significntly higher t the relese site thn t the control site in My of 5 (the first smple), suggesting tht the two sites did not hve equivlent mile--minute weed popultions t the strt of the experiment. However, over the next yers there ws grdul

5 5 J. Hough-Goldstein et l. / Biologicl 5 (9) NJ- MM % cover 7 Relese Fig.. Mile--minute weed percent cover, site NJ-. sterisk indictes significnt difference etween relese nd control qudrts (P.5, t-tests conducted on rcsin-trnsformed percent cover dt; originl mens nd SEMs shown). NJ- Spring smples (relese only) NJ- Weevils per qudrt Relese 7 (relese only) (relese only) MM seedlings 5 7 MM % cover 5 7 Fig. 5. Mile--minute weed seedlings nd percent cover in My, site NJ-, relese site only. Brs with the sme letter re not significntly different from ech other over different yers (P >.5, NOV nd LSD comprisons conducted on squre root-trnsformed seedling counts nd rcsin-trnsformed percent cover dt; originl mens nd SEMs shown). c Fig.. Rhinoncomimus ltipes dults per qudrt, site NJ-. sterisk indictes significnt difference etween relese nd control qudrts (P.5, t-tests conducted on squre root-trnsformed weevil counts; originl mens nd SEMs shown). reduction in the numers of P. perfolit seedlings nd percent cover in the spring smples t the relese site, from over per qudrt (5% cover) in 5, to fewer thn (% cover) in (Fig. ), while seedling numers in the control site did not differ significntly etween 5 nd 7. Spring percent cover ws lower t control site DE- in thn in 5, ut susequently incresed t this site in 7 (Fig. ). Weevils were undnt t the relese site in through 7 nd were present ut t generlly lower numers ech yer t the control site (Fig. ). Weevil counts in ugust verged 9. ±. per qudrt t the relese site nd.7 ±.5 t the control site. Percent cover of mile--minute weed remined reltively high t oth sites through 7 (Fig. ), nd in mid-ugust of ws still. ± 9.% t the relese site, not significntly different from the control (7. ±.%) or from the relese site the previous yer ( ugust, 7:.5 ± 5.%; F,5 =., P =.5). t MD- on Grrett Islnd, the mile--minute weed popultion ws less dense thn t the New Jersey nd Delwre sites, with spring seedling counts verging 9 per qudrt in. lthough weevils were found ner the relese site in during the summer following the spring relese nd in the monitored qudrts in 7 nd, numers remined low (dt not shown). Conditions were extremely dry during the summer of 7, cusing mile--minute weed plnts to die ck t oth the relese nd the control plots t this site, with percent cover verging only

6 J. Hough-Goldstein et l. / Biologicl 5 (9) NJ- MM % cover (relese only) DE- Weevils per qudrt Relese (control only) Fig. 7. Mile--minute weed percent cover, NJ- relese site. DE- Spring smples MM seedlings Relese 5 7 Fig. 9. Rhinoncomimus ltipes dults per qudrt, site DE-. sterisk indictes significnt difference etween relese nd control qudrts (P.5, t-tests conducted on squre root-trnsformed weevil counts; originl mens nd SEMs shown). Similr results were found t the Ohio River Islnd NWR sites in West Virgini. lthough seedling numers nd percent cover were firly high in My of 5 nd, in the spring of 7 lte frost pprently killed mny plnts in ll relese nd control plots (dt not shown). By ugust of 7, the percent mile--minute weed cover verged etween % nd % t ll WV sites. Weevil numers were lso low, nd were found t ll control sites within one or yers (Tle ).. Discussion MM % cover 5 7 Fig.. Mile--minute weed seedlings nd percent cover in My, site DE-. Brs with the sme letter (lower cse for relese, upper-cse for control) re not significntly different from ech other over different yers; pired relese nd control rs ech yer with n sterisk re significntly different from ech other (P.5, NOV nd LSD comprisons conducted on squre root-trnsformed seedling counts nd rcsin-trnsformed percent cover dt; originl mens nd SEMs shown). 5% t ll sites y July 7. Weevils were found t the control site within yer of relese. Rhinoncomimus ltipes weevils were le to overwinter nd estlish field popultions in out of 5 sites (9.9%) where they were relesed etween nd 7, rnging from northern New Jersey west to the Ohio River Vlley nd south to Howrd County, Mrylnd. Their hrdiness nd ility to thrive in vriety of settings ws predicted, ecuse in Chin they re widely distriuted in nine provinces from north to south, including Heilongjing province in northestern Chin, where winter tempertures cn rech lows of minus C (Ding et l., ). The weevil popultions were lso le to withstnd extremes of flooding. One of the 5 New Jersey relese sites ws locted ner the Delwre River nd experienced -yer flood in the spring of. The high wterline ws.5 m ove the relese site, nd weevils were not expected to survive, ut R. ltipes dults were oserved t the relese site in lte My tht yer nd in susequent yers. Weevils lso persisted t nother 5 relese site long the Delwre River in Slem County, New Jersey, which ws periodiclly flooded y tides. In its ntive rnge in si, P. perfolit is primrily riprin species nd thus my e dpted to survive nnul flooding (Hytt nd rki, ). The two releses where weevils did not successfully overwinter oth took plce in Octoer (one in nd one in 7), suggesting tht weevils relesed this lte in the yer my not hve suffi-

7 5 J. Hough-Goldstein et l. / Biologicl 5 (9) DE- Spring smples MM Seedlings Relese c c DE- MM % cover 7 Relese 7 5 MM % cover B 5 7 Fig.. Mile--minute weed seedlings nd percent cover in My, site DE-. Brs with the sme letter (lower-cse for relese, upper-cse for control) re not significntly different from ech other over different yers; pired relese nd control rs ech yer with n sterisk re significntly different from ech other (P.5, NOV nd LSD comprisons conducted on squre root-trnsformed seedling counts nd rcsin-trnsformed percent cover dt; originl mens nd SEMs shown). DE- Weevils per qudrt 7 B Relese Fig.. Rhinoncomimus ltipes dults per qudrt, site DE-. sterisk indictes significnt difference etween relese nd control qudrts (P.5, t-tests conducted on squre root-trnsformed weevil counts; originl mens nd SEMs shown). Fig.. Mile--minute weed percent cover, site DE- (relese nd control qudrts did not differ significntly; P >.5, t-tests conducted on rcsin-trnsformed percent cover dt; originl mens nd SEMs shown). cient time to cclimte efore winter s onset. R. ltipes stops lying eggs etween mid-ugust nd lte Septemer in southestern Pennsylvni (Lke, 7), ut dults continue to feed on mile-minute weed folige in preprtion for overwintering. Two other releses in tht were conducted on the sme dte in Octoer (nd with the sme numer of weevils, ) s the one tht filed, however, did estlish, nd thus lck of time for cclimtion ws not the sole reson for filure. Conditions were somewht rocky nd dry t the site tht filed, which my hve contriuted to weevil overwintering mortlity. The 7 relese tht filed ws conducted with older lortory weevils, proly less vigorous thn the newly emerged weevils typiclly used for releses, which my hve contriuted to this filure (s found, for exmple, y Center et l. (), for psyllid iologicl control gent). This relese ws lso the smllest, with only 59 individuls relesed, nd thus low propgule size my hve contriuted to filure (e.g., Memmott et l., 5). t ll relese sites where monitoring occurred, pired control sites were lso estlished, in n ttempt to mesure the effects of weevil feeding on mile--minute weed popultions compred to similr popultions without the weevil, s recommended y McCly (995) nd more recently y Crson et l. (), mong others. Seven of the eight control plots were colonized within yers, with n verge dispersl rte of 5 5 m/yer. The most remote control plot, however, ws found in yers, indicting dispersl t n verge rte of.5 km/yer, consistent with the verge dispersl rte of. km/yer estimted from nonrelese recovery sites in New Jersey, most of which were discovered or yers fter the nerest releses hd een mde. The. km/yer estimte is conservtive, since the weevils my hve rrived sooner thn when they were discovered. These oservtions were not prt of systemtic effort to trck dispersl, ut generlly occurred when stff from the New Jersey Beneficil Insect Lortory visited new mile--minute site in preprtion for relesing weevils nd found tht it ws lredy colonized. This rte of dispersl is greter thn tht of severl other iocontrol gents. For exmple, the weevil Oxyops vitios (Pscoe), introduced for control of Melleuc quinquenervi (Cv.) Blke in South Florid, dispersed t rte of.. km/yer (Prtt et l., ). phthon nigriscutis Foudrs (Coleopter: Chrysomelide) relesed for control of lefy spurge in Cnd spred t rte of only 5 m per yer in the first few yers (McCly, 995). The spred of R. ltipes ws similr to tht of the psyllid Boreioglycspis melleuce Moore, which spred t n verge rte.7 km/yer (Center et l., ). Despite reltively rpid dispersl, redistriution efforts, espe-

8 J. Hough-Goldstein et l. / Biologicl 5 (9) cilly to mile--minute weed ptches t the edges of the plnt s current distriution, in Rhode Islnd, Connecticut, Msschusetts, nd New York Stte to the north nd Virgini to the south, would e eneficil nd in some cses re lredy underwy. Despite dispersl of the weevils into the controls, significnt differences in mile--minute weed popultions in the presence nd sence of the weevil were found t three sites, NJ-, DE-, nd DE-. t oth NJ- nd DE-, mile--minute weed densities t the relese nd control sites were comprle t the strt of the study in 5, ut y the end of 7 weed densities t the relese site were 5% or less of wht they hd een t the strt of the study, while densities t the control site were lrgely unchnged. t site DE-, the control site hd lower mile--minute weed popultion thn the relese site initilly, ut did not chnge in seedling numers for yers, while seedling numers t the relese site were reduced to out 5% of their initil density. The less convincing ut more conventionl efore-nd-fter comprisons t site NJ- (where the control site ws ndoned following rpid weevil coloniztion) lso showed significnt reductions in the mile-minute weed popultion long with lrge increses in weevil numers over yers. The design used here ws similr to the Before-fter-- Impct (BCI) design descried y Osenerg nd Schmitt (99) for ssessing ecologicl impcts of humn-cused perturtions, in this cse relese of weevils. With this design, sptil vriility mong field sites is controlled y looking t the sme site over time (efore nd fter), nd temporl vriility, i.e., chnges tht will occur t ll sites over time whether the impct of the humn perturtion is present or not, is controlled for y monitoring control sites over the sme time period s the impcted sites. This design proved vlule here despite firly rpid weevil dispersl into the controls, nd provided convincing evidence of the impct of R. ltipes on mile--minute weed popultions over yers t severl different loctions. t oth the Grrett Islnd, Mrylnd, nd the Ohio River Islnds, West Virgini, sites, the mile--minute weed popultions collpsed within ll monitored qudrts, relese nd control sites, fter or yers. The reduced mile--minute weed popultions were proly due lrgely to environmentl fctors such s severe drought nd lte spring frost t these sites, rther thn to effects of weevil feeding. Hytt nd rki () similrly found tht in permnent qudrts strting with reltively low densities of mile--minute weed seedlings (nd efore ny insects hd een relesed) plnt popultion growth rtes were highly vrile, with severl popultions showing negtive growth rtes within the qudrts. It my e tht mile--minute weed is reltively poor competitor when it is present initilly t low densities nd in the presence of competing plnt species, nd depends on disturnce nd dispersl of its lrge seed crop to mintin metpopultion. Results from monitored sites suggest tht, once estlished, R. ltipes is cple of producing the popultion outreks tht re often ssocited with successful iologicl control of weeds (Vn Driesche et l., ). The monitoring protocol likely produced n undercount of ctul weevil numers, ecuse dults re very smll ( mm long), sometimes rest or feed on the underside of leves or hidden in terminls, nd my drop to the ground when distured. Nevertheless, enough weevils were visile to llow for counts of up to (t NJ-) to.5 (t DE-) on verge per.5- m qudrt. In this study weevil counts were not djusted sed on the percent cover of mile--minute weed in the qudrts, s ws done, for exmple, y Lke (7) nd thus s cover declined, weevil counts per qudrt lso tended to decline. The monitoring protocol sed on permnent qudrts, s recommended y Blossey nd Skinner (), proved fesile for coopertors t vrious sites nd provided n dequte ssessment of chnges in the plnt nd insect communities over time. Comprisons etween control nd relese sites, however, will ecome less fesile s R. ltipes continues to disperse throughout the rnge of its host plnt. cknowledgments We thnk Rchel Cliche, formerly of the Chespeke Islnd Refuges (including Grrett Islnd), who oversw monitoring nd contriuted dt from tht site. Megn Schiff, Kelsey Prs, Jmie Pool, Shne LCoss, nd Rchel Schnitmn ssisted with monitoring in Delwre. We thnk Dniel Plmer, my Diercks, Cryl Ott, nd Tom Dorsey, New Jersey Deprtment of griculture, for rering nd supplying the weevils. Thnks to Fred Doutthit nd Vince D mico for ssisting with preprtion of the relese site mp. Funding ws provided y the Forest Helth Technology Enterprise Tem, USD Forest Service, Morgntown, West Virgini. References Blossey, B., Skinner, L.,. Design nd importnce of post-relese monitoring. In: Spencer, N.R. (Ed.), Proceedings of the X Interntionl Symposium on Biologicl of Weeds. Montn Stte University, Bozemn, Montn, US, pp Crson, W.P., Hovick, S.M., Bumert,.J., Bunker, D.E., Pendergst, T.H.,. Evluting the post-relese efficcy of invsive plnt iocontrol y insects: comprehensive pproch. rthropod-plnt Interctions, 77. Center, T.D., Prtt, P.D., Tipping, P.W., Rymjhi, M.B., Vn, T.K., Wineriter, S.., Dry Jr., F.., Purcell, M.,. Field coloniztion, popultion growth, nd dispersl of Boreioglycspis melleuce Moore, iologicl control gent of the invsive tree Melleuc quinquenervi (Cv.) Blke. Biologicl 9, 7. Colpetzer, K., Hough-Goldstein, J., Ding, J., Fu, W.,. Host specificity of the sin weevil, Rhinoncomimus ltipes Korotyev (Coleopter: Curculionide), potentil iologicl control gent of mile--minute weed, Polygonum perfolitum L. (Polygonles: Polygoncee). Biologicl, 5 5. Colpetzer, K., Hough-Goldstein, J., Hrkins, K., Smith, M.,. Feeding nd oviposition ehvior of Rhinoncomimus ltipes Korotyev (Coleopter: Curculionide) nd its predicted effectiveness s iologicl control gent for Polygonum perfolitum L. (Polygonles: Polygoncee). Environmentl Entomology, Ding, J., Fu, W., Rerdon, R., Wu, Y., Zhng, G.,. Explortory survey in Chin for potentil insect iocontrol gents of mile--minute weed, Polygonum perfolitum L., in Estern US. Biologicl, Hough-Goldstein, J., Lke, E., Rerdon, R., Wu, Y.. Biology nd Biologicl of Mile--Minute Weed. USD Forest Service, FHTET--. Hough-Goldstein, J., Schiff, M., Lke, E., Butterworth, B.,. Impct of the iologicl controlgent Rhinoncomimus ltipes (Coleopter: Curculionide) on mile--minute weed, Persicri perfolit, in field cges. Biologicl, 7. Hytt, L.., rki, S.,. Comprtive popultion dynmics of n invding species in its ntive nd novel rnges. Biologicl Invsions, 75. Lke, E.C., 7. Dispersl, estlishment, nd impct of the mile--minute weevil, Rhinoncomimus ltipes Korotyev (Coleopter: Curculionide): two-yer study in Southestern Pennsylvni. M.S. Thesis, University of Delwre, Newrk. McCly,.S., 995. Beyond efore-nd-fter: experimentl design nd evlution in clssicl weed iologicl control. In: Delfosse, E.S., Scott, R.R. (Eds.), Proceedings of the VIII Interntionl Symposium on Biologicl of Weeds. DSIR/CSIRO, Melourne, ustrli, pp. 9. McCormick, L.H., Hrtwig, N.L., 995. of the noxious weed mile--minute (Polygonum perfolitum) in reforesttion. Northern Journl of pplied Forestry, 7. Memmott, J., Crze, P.G., Hrmn, H.M., Syrett, P., Fowler, S.V., 5. The effect of propgule size on the invsion of n lien insect. Journl of niml Ecology 7, 5. Mountin, W.L., 99. Mile--minute (Polygonum perfolituml.) updte distriution, iology, nd control suggestions. Regultory Horticulture 5,. Osenerg, C.W., Schmitt, R.J., 99. Detecting ecologicl impcts cused y humn ctivities. In: Schmitt, R.J., Osenerg, C.W. (Eds.), Detecting Ecologicl Impcts: Concepts ndpplictions incostl Hitts. cdemic Press, Sn Diego, pp.. Prtt, P.D., Slone, D.H., Rymjhi, M.B., Vn, T.K., Center, T.D.,. Geogrphic distriution nd dispersl rte of Oxyops vitios (Coleopter: Curculionide), iologicl control gent of the invsive tree Melleuc quinquenervi in south Florid. Environmentl Entomology, 97. Price, D.L., Hough-Goldstein, J., Smith, M.T.,. Biology, rering, nd preliminry evlution of host rnge of two potentil iologicl control gents for mile-minute weed, Polygonum perfolitum L. Environmentl Entomology, 9. Vn Driesche, R., Hoddle, M., Center, T.,. of Pests nd Weeds y Nturl Enemies. Blckwell Pulishing, Mlden, M. Wu, Y., Rerdon, R.C., Ding, J.,. Mile--minute weed. In: Vn Driesche, R., Lyon, S., Blossey, B., Hoddle, M., Rerdon, R. (Eds.), Biologicl of Invsive Plnts in the Estern United Sttes. USD Forest Service Puliction FHTET--, pp..