Edge Effects in the Directionally Biased Distribution of Choristoneura rosaceana (Lepidoptera: Tortricidae) in Apple Orchards

Transcription

1 SAMPLING Edge Effects in the Directionlly Bised Distribution of Choristoneur roscen (Lepidopter: Tortricide) in Apple Orchrds C. L. HSU, 1 A. M. AGNELLO, AND W. H. REISSIG Cornell University, New York Stte Agriculturl Experiment Sttion, 630 W. North St., Genev, NY Environ. Entomol. 38(2): 433Ð441 (2009) ABSTRACT Edge effect tests hve been used in number of studies on obliquebnded lefroller, Choristoneur roscen (Hrris), to test for evidence of mted femle immigrtion into pheromonetreted orchrds. This type of test compres obliquebnded lefroller presence or ctivity round the perimeter of n orchrd ginst presence or ctivity in the interior. Higher numbers detected round the edges of n orchrd would indicte higher levels of ßight ctivity t the edge, pttern tht could be generted by high levels of immigrtion. Recent work hs shown tht the sptil distribution of recptured obliquebnded lefroller dults relesed from single loction cn be directionlly bised, which could obscure the bility to detect n edge effect. To test this theory, dt from n orchrd study conducted in 1991 tht found no signiþcnt edge effect ws renlyzed. When we ccounted for the directionl bis in the distribution of Þrst-genertion mted femle moths, we found n edge effect with signiþcntly more mted femles cptured in the edge trps thn in the center or mid-interior trps. No edge effect ws found when the directionl bis ws ignored. In ddition, second-genertion mles nd mted femles both showed signiþcnt edge effect tht hd not been detected in the originl nlysis, which hd combined both Þrst- nd second-genertion dt. KEY WORDS directionl orienttion, immigrtion, dispersl, edge effects, pheromone control Obliquebnded lefroller, Choristoneur roscen (Hrris), is key pest in pples (Reissig 1978, Mdsen et l. 1984, Agnello et l. 1996, Lwson et l. 1996, Pree et l. 2001), pers (Knight et l. 1998, Pree et l. 2001), cherries (Knight et l. 1998), Þlberts (AliNizee 1986), rspberries (Li et l. 1995, Li nd Fitzptrick 1997), nd peches (Pree nd Roberts 1981, Kethler et l. 1982). Attempts to control obliquebnded lefroller in pple orchrds using pheromones for mting disruption hve shown inconsistent results (Agnello et l. 1996, Lwson et l. 1996, Knight et l. 1998, Trimble nd Appleby 2004, Stelinski et l. 2005), nd dmge in pheromone-treted orchrds cn be bove cceptble levels (Agnello et l. 1996). One possible explntion for these results is mted femle immigrtion. The immigrtion behvior of mted femles is considered the most crucil trit ffecting the susceptibility of pest to control using pheromone disruption (Crdé nd Minks 1995). If there is substntil immigrtion of grvid femles into pheromone-treted orchrd, even complete disruption of within-orchrd mting might not result in sufþcient suppression of pest dmge. One common method used to detect immigrtion is n edge effect test tht compres insect presence or ctivity round the perimeter of site with tht in the interior. Higher numbers detected round the edges 1 Corresponding uthor, e-mil: clh33@cornell.edu. of n orchrd would indicte higher levels of ßight ctivity t the edge, pttern tht could be generted by high levels of immigrtion. In previous studies testing for n edge effect in obliquebnded lefroller distributions, no differences were found in the percentge of mle, mted femle, or virgin femle dults cptured in trps locted t the edge or interior of orchrds (Agnello et l. 1996, Lwson et l. 1996, Knight et l. 1998). Studies hve looked for differences in the number of moths cptured using molsses bit trps (Agnello et l. 1996), differences using pssive interception trps (Lwson et l. 1996), nd differences in the number of tethered virgin femles tht were mted in edge nd interior trps (Lwson et l. 1996, Knight et l. 1998). Mesures of lrvl infesttion nd fruit dmge lso showed no differences between edge nd interior loctions (Lwson et l. 1996, Knight et l. 1998). The bsence of n edge effect in orchrds hs been ttributed to the possibility tht most obliquebnded lefrollers originte within the pple orchrd or tht immigrting moths cnnot be detected using the trpping methods vilble (Lwson et l. 1996). We suggest nother possible reson is directionlly bised immigrtion, which would result in some edge trps hving consistently higher ctches thn others. Mrkrelese-recpture experiments done by Hsu (2002) found signiþcnt directionl bis in the sptil distribution of recptured mle, mted femle, nd virgin X/09/0433Ð0441$04.00/ Entomologicl Society of Americ

2 434 ENVIRONMENTAL ENTOMOLOGY Vol. 38, no. 2 femle obliquebnded lefroller dults relesed from single loction in n experimentl pple orchrd tht hd no rtiþcil pheromone tretments. Directionlly bised immigrtion could mke it more difþcult to detect sttisticlly signiþcnt difference between the edge nd interior tretments becuse the edge trps would hve higher vrince becuse of the bised sptil distribution of the moths. To test this possibility, we renlyzed dt from 1991 study (Agnello et l. 1996) conducted in pheromone-treted orchrds to determine whether directionl bis in the sptil distribution of moths could interfere with the bility to detect sttisticlly signiþcnt edge effect. Mterils nd Methods Agnello et l. (1996) conducted series of pheromone control studies in grower orchrds between 1989 nd We renlyzed dt from their 1991 study. The 1991 study used four orchrds (herefter referred to s orchrds 1, 2, 3, nd 4) in Orlens nd Wyne Counties, NY. Ech orchrd contined two types of pheromone dispensers relesing n obliquebnded lefroller nturl pheromone blend (90:5:5% Z/E11Ð14:OAc, Z11Ð14:OH). In ech orchrd, 24 bit trps were rrnged in concentric rings t three loctions: 4 trps in the center, 8 trps in the midinterior, nd 12 trps plced round the edge (Agnello et l. 1996). The bit trps consisted of 1-liter plstic bucket covered with hrdwre cloth (0.6-cm 2 mesh) nd bited with 300 ml of molsses nd grnulted bkerõs yest bit (1:10 molsses:wter plus 1.1 g of yest per liter of solution). Bit trps were hung from scffold brnches 1 m bove ground. Moths were collected 21 times over the seson, twice weekly between 22 My nd 27 August In generl, the Þrst-genertion ßight of obliquebnded lefroller moths begins in erly June nd the secondgenertion ßight begins in erly August. In 1991, Þrstgenertion moths were cptured on the Þrst trpping dte, 22 My, nd the second-genertion ßight strted in mid-july (Agnello et l. 1996). These erly ßights my hve been cused by higher thn verge men tempertures throughout New York Stte in My, lthough men tempertures in June, July, nd August 1991 were similr to the verge (NOAA 1991). All moths were brought to the lbortory nd dissected to determine their sex nd mting sttus. In their originl nlysis using nlysis of vrince (ANOVA), Agnello et l. (1996) found no signiþcnt edge effect; i.e., there ws no difference in the percentge of mle, mted femle or virgin femle moths cptured in the three trp loctions. In our renlysis, ech bit trp ws ssigned 1 of 16 directionl orienttions seprted t 22.5 intervls with north 0. Ech direction ws represented by single trp except for the four corner directions (northest, southest, southwest, nd northwest), which were represented by three trps ech: center, mid-interior, nd edge trp. We renlyzed dt for ech genertion (Þrst genertion, 22 My to 2 July; second genertion, 17 July to 27 August) nd for ech moth ctegory (mle, mted femle, nd virgin femle) seprtely. For ech dte in ech orchrd, we used circulr sttistics to determine whether the distribution of cptured moths ws bised in prticulr direction. Circulr sttistics re commonly used to nlyze dt tht re directionl nd mesured in degrees or re cyclic/periodic in time, such s weeks or months. A chrcteristic of circulr dt re tht the beginning nd end points of the scle re the sme, e.g., 0 nd 360, nd the strting point cn be rbitrry. Clculting the men of two ngles, e.g., 10 nd 350, using liner methods would be inpproprite, becuse it would give n nswer of 180 when the true ngulr men is 0. In circulr sttistics, the equivlent of the norml distribution is the von Mises distribution, symmetric unimodl distribution (Fisher 1993). Similr to the norml distribution, which is deþned by the men,, nd the vrince, 2, mesure of dispersion, there re corresponding prmeters in circulr sttistics: the men ngle,, nd mesure of dispersion, (Fisher 1993). To test whether the men direction for collected moths showed evidence of signiþcnt (P 0.05) directionl bis, we used the Ryleigh test, which uses the null hypothesis tht the distribution of the dt re von Mises (Fisher 1993). The Ryleigh test uses two prmeters:, the men ngle of collected moths, which rnges between 0 nd 360, nd R, dispersion prmeter, which rnges between 0 nd 1 nd is the length of the men vector. The higher the R vlue, the longer the vector nd the more tightly concentrted the moths re round. P vlues re clculted using n pproximtion provided by Fisher (1993). If the distribution of the moths collected in the bit trps hd signiþcnt directionl bis using the Ryleigh test, the orchrd ws split in hlf using line perpendiculr to. Trps were ctegorized s being in or out of the men direction hlf, with n equl number of trps locted in the two hlves. When ws not signiþcnt, the men direction for ll trps for tht dte/orchrd ws considered out. For the corner directions, where there were three trps representing ech direction, the men number cptured per trp ws used to clculte nd R. For exmple, on 6 June 1991, mted femle moths cptured in one orchrd showed signiþcnt men directionl bis with 168. The 12 trps locted between 78 nd 258 were ssigned to the in ctegory, nd the 12 trps locted on the northern hlf of tht orchrd between 258 nd 78 were ssigned to the out ctegory. The gol of the nlysis ws to determine whether directionl bis in recptured moths could ffect the bility to detect signiþcnt edge effect. After ech trp ws ctegorized s in or out, the totl number of mle, mted femle, nd virgin femle moths cptured in ech genertion ws nlyzed to test for n edge effect. Becuse ech trp ws repetedly smpled over time, generlized estimting eqution (GEE) re-

3 April 2009 HSU ET AL.: EDGE EFFECTS IN THE DISTRIBUTION OF C. roscen IN APPLES 435 Tble 1. Dtes when the distribution of obliquebnded lefroller, C. roscen, dults cptured in bit trps in four orchrds hd significnt directionl bis Dte Orchrd (men direction) R P No. cptured First genertion 6 June Mted femles Orchrd (SSE) June Mted femles Orchrd (SSW) June Mles Orchrd (SE) Mles Orchrd (SW) Mted femles Orchrd (SE) June Mted femles Orchrd (WSW) Mted femles Orchrd (WNW) Virgin femles Orchrd (SSW) June Mles Orchrd (SSW) Mted femles Orchrd (SSW) Virgin femles Orchrd (SSW) June Virgin femles Orchrd (SSW) July Mted femles Orchrd 4 23 (NNE) Second genertion 22 July Mles Orchrd (SSW) July Mted femles Orchrd (S) Aug. Mted femles Orchrd (WNW) Aug. Mted femles Orchrd (SSE) Aug. Mles Orchrd (SSE) Virgin femles Orchrd (S) gression model ws used specifying the distribution s negtive binomil nd using n utoregressive correltion model [PROC GENMOD, dist negbin, type r(1); SAS Institute 2002]. The regression model included Julin dte collected, orchrd, trp loction (center, mid-interior, edge), men direction (in, out), nd ll possible two- nd three-wy interctions tht llowed the model to converge to Þnl solution. Finl results show only the P vlues for the miniml model tht includes min fctors nd those interction terms tht were signiþcnt. We did not nlyze dtes when moths were not cptured. A Bonferroni correction ws used for multiple comprison tests. In the originl nlysis, the totl 1991 trp ctch percentges for the yer were used in n ANOVA with n rcsine squre-root trnsformtion of the percentges to test for differences between the number of moths cptured in the edge, mid-interior, nd center of the orchrds (Agnello et l. 1996). This nlysis found no signiþcnt differences (Agnello et l. 1996). Our renlysis of the dt ws different in two wys: it considered the two genertions seprtely nd it used GEE regression model. To ssess whether differences between our conclusions nd those of Agnello et l. (1996) were ffected by our use of n lterntive sttisticl method or becuse of the inclusion of directionl bis in the nlysis, we lso renlyzed the dt using reduced model excluding the men direction fctor nd testing only the min effects of dte, orchrd, nd trp loction. Results from the reduced nd full models were compred to ssess the importnce of including the men direction in the nlysis. Results Mles. First-genertion mles showed signiþcnt bis in their distribution in 3 of 36 possible smples (8.3%): in orchrd 1 on 13 nd 20 June nd in orchrd 2 on 13 June (Tble 1). Trp loction ws not significnt (Tble 2), with similr men numbers of mles cptured in the three trp loctions (Fig. 1A). Men direction ws signiþcnt fctor in the Þrst genertion (Tble 2), with the verge number of mles per trp on the hlf of the orchrd tht ws in the men direction being signiþcntly higher thn the number of mles cptured in trps clssiþed s out of the men direction (in per trp [SD], N 36; out per trp, N 827; P 0.001). The men direction nd trp loction interction term ws not ssessed becuse the model did not converge when this term ws included (Tble 2). Trp loction ws still not signiþcnt when we used the reduced model tht included only dte, orchrd, nd trp loction. Second-genertion mles showed signiþcnt bis in their distribution in 2 of 40 possible smples (5.0%): in orchrd 1 on 22 July nd 26 August. Trp loction

4 436 ENVIRONMENTAL ENTOMOLOGY Vol. 38, no. 2 Tble 2. Significnce of trp loction (center, mid-interior, or edge) nd men direction (in or out s defined in the text) on the no. of obliquebnded lefroller, C. roscen, dults cptured per trp Source Mles Mted femles Virgin femles df Pr 2 df Pr 2 df Pr 2 First genertion Dte Orchrd Trp loction Men direction Trp men direction NA NA Orchrd men NA NA direction Second genertion Dte Orchrd Trp loction NS Men direction 1 NS 1 NS 1 NS NA, not pplicble, model including this fctor did not converge; NS, not signiþcnt t ws signiþcnt in the second genertion (Tble 2), with more second-genertion mles cptured in the edge nd center trps compred with the mid-interior trps (Fig. 1B). Men direction ws not signiþcnt, resulting in reduced model including only dte, orchrd, nd trp loction. Mted Femles. First-genertion mted femles hd signiþcnt directionlly bised distribution in 7 of 32 possible smples (21.9%): in orchrd 1 on 6, 10, 13, 17, nd 20 June, in orchrd 2 on 17 June, nd in orchrd 4 on 1 July (Tble 1). Trp loction ws signiþcnt, with more mted femles cptured in the edge trps compred with the mid-interior nd center trps (Fig. Men No. Cptured Per Trp Men No. Cptured Per Trp A B A B c c b Center Mid-interior Edge Mles Mted Femles Virgin Femles Center A Mid-interior Middle Edge b Mles Mted Femles Virgin Femles Fig. 1. Distribution of obliquebnded lefroller, C. roscen, dults cptured in center, mid-interior, nd edge trps in four pheromone-treted grower orchrds studied in (A) First genertion. (B) Second genertion. Mens with different letters within genertion nd sex or mting sttus ctegory re signiþcntly different t P Men No. Mted Femles Cptured per Trp Center Mid- Edge interior Outside Men Direction Center Mid- Edge interior Inside Men Direction Fig. 2. Distribution of mted femle obliquebnded lefroller, C. roscen, dults in four grower orchrds tht were divided in hlf when mted femles showed signiþcnt directionl bis s described in text. Mens with different letters re signiþcntly different t P A). There ws lso signiþcnt interction between men direction nd trp loction (Tble 2). For dtes when ws signiþcnt, more mted femles were cptured in the edge trps compred with the center nd mid-interior trps on the hlf of the orchrd tht ws in the men direction, but there ws no difference between the number of mted femles cptured in the center, mid-interior, nd edge trps locted on the hlf of the orchrd tht ws out of the men direction (Fig. 2). Trp loction ws not signiþcnt when we used reduced model tht included only dte, orchrd, nd trp loction. In the second genertion, mted femles hd signiþcnt directionl bis in their distribution in 3 of 44 smples (6.8%): in orchrd 1 on 29 July nd 5 August nd in orchrd 3 on 1 August (Tble 1). Similr to second-genertion mles, trp loction ws signiþcnt (Tble 2), with more second-genertion mted femles cptured in the edge nd center trps compred with the mid-interior trps (Fig. 1B). Men direction ws not signiþcnt, resulting in the reduced model including only dte, orchrd, nd trp loction. Virgin Femles. First-genertion virgin femles hd signiþcnt bis in their distribution in 3 of 32 smples (9.4%): in orchrd 1 on 17, 20, nd 24 June (Tble 1). Like Þrst-genertion mles, trp loction ws not signiþcnt, with similr men numbers of virgin femles cptured in the three trp loctions (Fig. 1A), nd men direction ws signiþcnt (Tble 2), with more virgin femles cptured in trps locted in the hlf of the orchrd tht ws in the men direction thn were cptured in trps clssiþed s out of the men direction (in per trp, N 36; out per trp, N 731; P 0.001). When we used reduced model including only dte, orchrd, nd trp loction, trp loction ws still not signiþcnt. Second-genertion virgin femles hd signiþcnt bis in their distribution in 1 of 40 smples (2.5%): in orchrd 1 on 26 August (Tble 1). Neither trp loction nor men direction ws signiþcnt for secondgenertion virgin femles (Tble 2; Fig. 1B). Discussion Our renlysis of the 1991 dt from Agnello et l. (1996) showed tht directionl bis in the sptil b

5 April 2009 HSU ET AL.: EDGE EFFECTS IN THE DISTRIBUTION OF C. roscen IN APPLES 437 distribution of recptured moths in n orchrd cn ffect the bility to detect sttisticlly signiþcnt edge effect. When the directionl bis in the distribution of Þrst-genertion mted femles ws tken into ccount, the results showed tht signiþcntly more mted femles were cptured in the edge trps. We detected no signiþcnt edge effect when this bised distribution ws not tken into ccount. For second-genertion moths, there ws no evidence tht bised directionl distribution ffected the nlysis results, but we did Þnd tht the number of mted femles nd mles ws signiþcntly higher in the edge nd center trps compred with the mid-interior trps. In contrst, the sptil distribution of virgin femles between edge, mid-interior, nd center trps ws uniform in both the Þrst nd second genertions. Agnello et l. (1996) did not Þnd sttisticlly signiþcnt edge effect for mted femles using ANOVA, nd they concluded tht mted femles were uniformly dispersed in the study orchrds. Our results suggest tht using more sensitive nlyticl method tht includes directionl informtion in the nlysis nd seprting the genertions before nlyzing them cn show more of the sptil pttern thn using n ANOVA nd nlyzing both genertions together. The dt collected by Agnello et l. (1996) in 1991 provided informtion on the sptil distribution of moths, but their study ws not designed to give ny insight into the cusl fctors. The men direction of mted femles ws most frequently signiþcnt in orchrd 1, with vlues rnging between 125 nd 248 (southest-southwest). Due north of orchrd 1 ws forested lnd, to the est ws pved rod, due south ws Þeld rod nd nother pple orchrd tht ws not treted with pheromone, nd to the west were pple trees tht were not prt of the study plot nd were not treted with pheromone (Fig. 3). We suggest some possible mechnisms tht my be contributing nd intercting to result in the bised sptil distribution ptterns we found for mted femles in orchrd 1. First, signiþcntly more mted femles were cptured in edge trps in both the Þrst nd second genertions cross ll four orchrds, pttern tht could reßect high levels of mted femle immigrtion. Higher numbers of mted femles long the southern edge of orchrd 1, speciþclly, could result from bised immigrtion into this orchrd by mted femles originting from the orchrd south of orchrd 1. We did not hve ccess to detiled historicl wether dt for orchrd 1 but winds, in generl, re west-southwest in this region of New York in June, when Þrst-genertion moths re ctive (NOAA 1998). If mted femles disperse in bised direction downwind, mted femles emigrting from the orchrds south of orchrd 1 would contct the southern border of orchrd 1 Þrst, incresing the number of mted femles long the southern edge. Higher numbers t the southern edge trps could lso result from bised directionl emigrtion of mted femles within orchrd 1 upwind, wy from the high levels of synthetic pheromone relesed in orchrd 1. North Wind Direction (WSW) Forested lnd Apple orchrd No synthetic pheromones Field Rod Apple orchrd No synthetic pheromones Mted femle spruce budworms, Choristoneur fumifern (Clem.) (Tortricide), increse their ßight ctivity when exposed to synthetic pheromone (Snders 1987), nd the proportion of femle light brown pple moths, Epiphys postvittn (Wlk.) (Tortricide), tht ßy increses with incresing popultion density (Dnthnryn 1976). Using electrontennogrm (EAG) mesures, Gokce et l. (2007) showed tht femle obliquebnded lefroller dults cn perceive their own sex pheromone. Mted femle lefrollers my increse their ßight ctivity in response to high pheromone concentrtions, or they could interpret higher levels of pheromone s n indiction of higher popultion density nd increse their ßight ctivity. An increse in ßight ctivity does not necessrily result in bised directionl distribution, but if mted femles hve preference for upwind ßight under high concentrtions of pheromone, this could result in sptil distribution pttern with more mted femles emigrting towrd the southern edge of orchrd 1. The sptil distribution of virgin femles in orchrd 1 my be third possible fctor determining the distribution of mted femles. There ws signiþcnt southern bis in the sptil distribution of Þrst-genertion virgin femles cptured in orchrd 1: 196Ð210. Higher popultions of virgin femles in the southern trees could result in higher subsequent popultions of mted femles, which would help explin the overll bised southern distribution of mted femles. However, this does not completely explin the sptil distribution of mted femles, becuse virgin femles were distributed evenly between the edge, midinterior, nd center trps in the south, wheres signiþcntly more mted femles were locted in the XX XX Edge trps Mid-interior trps X Center trps Pved Rod Fig. 3. Mp of orchrd 1 (not drwn to scle). Smll rrow indictes verge wind direction in June in this region of New York.

6 438 ENVIRONMENTAL ENTOMOLOGY Vol. 38, no. 2 edge trps. This secondry Þner-scle sptil pttern could result from fourth possible mechnism: higher mting success long the southern edge of the orchrd, possibly cused by lower synthetic pheromone concentrtions. Pheromone concentrtions long trnsect between pheromone-treted nd n untreted pple orchrd were shown to decline in the pheromone-treted orchrd up to 20 m from the border when the wind ws blowing obliquely from the untreted side (Milli et l. 1997). Witzgll et l. (1999) found signiþcntly lower pheromone concentrtions in border trees t the upwind edge of n orchrd in pheromone-treted orchrds. The southern edge of orchrd 1 is the upwind side, nd higher mting success long this edge cused by lower synthetic pheromone concentrtions could result in higher numbers of mted femles in the southern edge trps. The lst possible mechnism we present is reßecting boundry rection (Schtickzelle nd Bguette 2003). If mted femles detect chnge in the environment when dispersing from orchrd 1 into the Þeld rod south of orchrd 1, nd, in response, return to orchrd 1, this would increse their overll ßight ctivity in the southern edge of the orchrd, incresing the probbility of higher trp ctch long the southern edge compred with the mid-interior nd center trps. A reßecting boundry could lso ffect mted femle dispersl behvior long the north nd est edges of orchrd 1, which border forest nd pved rod, but there my hve been too little ßight ctivity in these sections to show signiþcnt edge effect given tht there were signiþcntly more mted femles cptured in the southern end of the orchrd. Considerble reserch shows tht mles of mny species of moths ßy upwind in the presence of pheromones (Crdé nd Willis 2008). Considerbly less is known bout whether mted femle moths respond to wind direction, nd, if they do, whether their response is different in the presence or bsence of high concentrtions of pheromone. Additionl Þeld nd lbortory studies re necessry to determine which, if ny, of these possible mechnisms re ffecting the ßight behvior of mted femles nd the mting success of virgin femle moths. A better understnding of mted femle dispersl behvior would be prticulrly useful becuse mted femle immigrtion is still considered one of the most importnt fctors ffecting the success of pheromone disruption control progrms (Crdé nd Minks 1995). Our nlysis results lso suggest tht there re differences in the sptil distribution ptterns of moths s function of sex nd mting sttus. Mted femles in both the Þrst nd second genertions showed bised directionl distribution more frequently thn did either mles or virgin femles. In contrst, dt from mrk-relese-recpture Þeld studies where moths were relesed from single site in n pple orchrd tht hd no synthetic pheromones showed tht recptured mle lefrollers were more likely to hve signiþcnt directionlly bised distribution thn either mted or virgin femles (Hsu 2002). An upwind bis in dispersl is commonly found in mles responding to pheromone plumes in the presence of wind (Crdé nd Willis 2008). When exposed to homogeneous pheromone environments, however, studies show tht mles in two relted species of tortricids, the summerfruit tortrix, Adoxophyes orn (Fischer von Röslerstmm), nd the orientl fruit moth, Grpholit molest (Busck), cese their bised upwind ßight behviors (Kennedy et l. 1981, Willis nd Bker 1984). All four orchrds used in 1991 were treted with synthetic pheromone, nd this might explin why so few of the mle dt sets from 1991 showed signiþcnt directionl bis in their sptil distribution while mles in n untreted orchrd often hd signiþcnt directionlly bised distribution. An dditionl insight gined from our renlysis is evidence tht the dispersl behvior of Þrst- nd second-genertion moths might be qulittively different: there ws no signiþcnt directionl bis in the distribution of second-genertion mles, mted femles, or virgin femles in the 1991 study, but men direction ws signiþcnt fctor lone or s n interction term for ll three ctegories of moths in the Þrst genertion. In ddition, there ws no signiþcnt difference in the number of moths cptured in the edge, mid-interior nd center trps for Þrst-genertion mles, but in the second genertion, signiþcntly more mles were cptured in the edge nd center trps compred with the mid-interior trps. The possibility tht Þrst- nd second-genertion dults hve consistently different dispersl behviors is worth exploring in future studies. Alterntive control mesures trgeting immigrting mted femles might be more successful in the Þrst thn in the second genertion if dditionl evidence suggests tht the edge effect is cused by mted femle immigrtion. Likewise, pheromone control might be more successful with secondthn Þrst-genertion dults if the totl number of second-genertion mted femles immigrting into pheromone-treted orchrds is lower. Unfortuntely, there re no historicl records of trp ctch dt using bit pils tht cn be used to compre the popultion cptured in 1991 with other yers, but we believe the popultion cptured in 1991 ws not unusul. Consecutive yers of pheromone trils in Orlens nd Wyne Counties between 1989 nd 1999 show tht obliquebnded lefroller popultions vry considerbly from yer to yer nd between orchrds. Pheromone trp ctch numbers, infesttion levels, nd dmged fruit levels found in 1991 were well within the bounds of vrition observed over this 10-yr period (A.M.A. nd W.H.R., unpublished dt). After 4 yr of pheromone trils, Agnello et l. (1996) concluded tht the effectiveness of pheromone disruption control strtegy needed to be tested t much lrger scle thn ws used in their studies. Our renlysis results support this generl conclusion. We found signiþcntly more Þrst- nd second-genertion mted femles in edge trps, suggesting tht the immigrtion potentil of mted femles my be operting t lrger sptil scle thn the size of the pheromonedisrupted plots. More recent studies pplying pheromones on n re-wide bsis, where the perimeter:

7 April 2009 HSU ET AL.: EDGE EFFECTS IN THE DISTRIBUTION OF C. roscen IN APPLES 439 re rtio is lower, hve shown improved efþccy ginst codling moths, Cydi pomonell L., nd orientl fruit moths in the northwestern United Sttes: Michign nd Pennsylvni (Brunner et l. 2001; IlÕichev et l. 2002; Clkins nd Fust 2003; Gut et l. 2004; Epstein et l. 2007; Hull et l. 2007, 2008). Tests of re-wide pheromone disruption trgeting obliquebnded lefrollers hve not been conducted but could show similr results. Including directionl nlysis into tests for edge effects is not difþcult if enough trps re ssocited with ech ngulr direction. In ll of the studies conducted by Agnello et l. (1996) between 1989 nd 1992, only the dt from the 1991 study ws pproprite for this type of nlysis becuse the trps were rrnged in three concentric rings within the orchrd. Dt collected using trnsects re generlly not mendble to circulr nlysis unless there re trnsects in t lest the four crdinl directions in the sme study plot. Circulr sttistics re reltively simple nd powerful tool, nd n nlysis of ny type of sptil distribution or dispersl dt cn beneþt from identifying directionl bis, which cn suggest new hypotheses to be tested. The Ryleigh test cn be done using spredsheet or commercilly vilble softwre, nd there is growing body of literture to guide users in more dvnced nlyses, such s hypothesis testing, regression, nd prediction (Btschelet 1981, Fisher 1993, Jmmlmdk nd SenGupt 1998, Presnell et l. 1998, Lund 1999, Mrdi nd Jupp 2000, Jmmlmdk nd SenGupt 2001, Downs nd Mrdi 2002, Ghosh et l. 2003). In dditionl to nlyzing sptil distribution ptterns, the Þeld of entomology hs beneþtted from the use of circulr sttistics to study orienttion behvior in the presence or bsence of odors (Brdy nd Grif- Þths 1993; Evns nd Allen-Willims 1993, 1994; Guevr et l. 2000; Otálor-Lun et l. 2004), orienttion in response to mgnetic Þelds nd polrized light (Hvukkl nd Kennedy 1984, Shen et l. 1998, Bnks nd Srygley 2003, Stlleicken et l. 2005), forging behvior to locte hosts, hbitt, or mtes (Toepfer et l. 1999, Durier nd Rivult 2000, Fourcssié nd Oliveir 2002, Szentesi et l. 2002, Kost et l. 2005), nd dispersl in generl (Hsu 2002, Morse 2002, Desouhnt et l. 2003, Roux et l 2006). Additionlly, studies in insect physiology (Yetmn nd Pollck 1987, Den 1992, Pfeiffer et l. 2005) nd circdin rhythms (Gimenes et l. 1996, Klrsfeld e tl. 2003, Chhd- Ehlers et l. 2007) hve used circulr sttistics. In conclusion, we showed tht the bility to detect sttisticlly signiþcnt edge effect in obliquebnded lefroller dults in pple orchrds is sensitive to whether there is directionl bis in the sptil distribution of the moths nd to nlyzing the genertions seprtely. We recommend tht these fctors be considered when testing for edge effects in future studies. We hve lso introduced the use of circulr sttistics nd GEE regression models s tools tht could be used in other studies where the dt hve directionl component, do not follow norml distribution, nd re collected repetedly over time. Acknowledgments We thnk the nonymous reviewers for very constructive comments, C. Linn for generous nd insightful comments on erly versions of this mnuscript, F. Vermeylen for sttisticl ssistnce, nd B. Nult nd S. C. Wise for support. Funding for this work ws provided by the Science to Achieve Results Fellowship Progrm, U.S. Environmentl Protection Agency, Grnt References Cited Agnello, A. M., W. H. Reissig, S. M. Spngler, R. E. Chrlton, nd D. P. Kin Trp response nd fruit dmge by obliquebnded lefroller (Lepidopter: Tortricide) in pheromone-treted pple orchrds in New York. Environ. Entomol. 25: 268Ð282. AliNizee, M. T Sesonl history, dult ßight ctivity, nd dmge of the obliquebnded lefroller, Choristoneur roscen (Lepidopter: Tortricide) in Þlbert orchrds. Cn. Entomol. 118: 353Ð361. Bnks, A. N., nd R. B. Srygley Orienttion by mgnetic Þeld in lef-cutter nts, Att colombic (Hymenopter: Formicide). Ethology 109: 835Ð846. Btschelet, E Circulr sttistics in biology. Acdemic, London, United Kingdom. Brdy, J., nd N. Griffiths Upwind ßight responses of tsetse ßies (Glossini spp.) (Dipter: Glossinide) to cetone, octenol nd phenols in nture: video study. Br. Entomol. Res. 83: 329Ð333. Brunner, J., S. Welter, C. Clkins, R. Hilton, E. Beers, J. Dunley, T. Unruh, A. Knight, R. VnSteenwyk, nd P. Vn Buskirk Mting disruption of codling moth: perspective from the Western United Sttes. IOBC TPRS Bull. 25: 207Ð215. Clkins, C. O., nd R. J. Fust Overview of rewide progrms nd the progrm for suppression of codling moth in the Western USA directed by the United Sttes Deprtment of AgricultureÐAgriculturl Reserch Service. Pest Mng. Sci. 59: 601Ð604. Crdé, R. T., nd A. K. Minks Control of moth pests by mting disruption. Annu. Rev. Entomol. 40: 559Ð585. Crdé, R. T., nd M. A. Willis Nvigtionl strtegies used by insects to Þnd distnt, wind-borne sources of odor. J. Chem. Ecol. 34: 854Ð866. Chhd-Ehlers, S., A. L. Lozovei, nd M. D. Mrgues Reproductive nd post-embyronic dily rhythm ptterns of the mlri vectors Anopheles (Kerteszi) crusii: spects of the life cycle. Chronobiol. Int. 24: 289Ð304. Dnthnryn, W Flight thresholds nd sesonl vritions in ßight ctivity of the light-brown pple moth, Epiphys postvittn (Wlk.) (Tortricide), in Victori, Austrli. Oecologi (Berl.) 23: 271Ð282. Den, J A model of leg coordintion in the stick insect, Crusius morosus. Biol. Cybern. 66: 345Ð355. Desouhnt, E., G. Driessen, L. Lpchin, nd S. Wielrd Dispersl between host popultions in Þeld conditions: nvigtion rules in the prsitoid Venturi cnescens. Ecol. Entomol. 28: 257Ð267. Downs, T. D., nd K. V. Mrdi Circulr regression. Biometrik 89: 683Ð697. Durier, V., nd C. Rivult Lerning nd forging ef- Þciency in Germn cockroches, Blttel germnic (L.) (Insect: Dictyopter). Anim. Cogn. 3: 139Ð145.

8 440 ENVIRONMENTAL ENTOMOLOGY Vol. 38, no. 2 Epstein, D., L. Gut, nd P. McGhee Arewide pproch to mnging codling moth in Michign pple production. Finl report: FQPA/Strtegic Agriculturl Inititive Progrm Grnt. EPA Region 5/Americn Frmlnd Trust, Michign Stte University, Est Lnsing, MI. Evns, K. A., nd L. J. Allen-Willims Distnt olfctory response of the cbbge seed weevil, Ceutorhynchus ssimilis, to oilseed rpe odour in the Þeld. Physiol. Entomol. 18: 251Ð256. Evns, K. A., nd L. J. Allen-Willims Lbortory nd Þeld response of the pollen beetle, Meligethes eneus, to the odour of oilseed rpe. Physiol. Entomol. 19: 285Ð290. Fisher, N. I Sttisticl nlysis of circulr dt. Cmbridge University Press, New York. Fourcssié, V., nd P. S. Oliveir Forging ecology of the gint Amzonin nt Dinophoner gignten (Hymenopter, Formicide, Pnerine): ctivity schedule, diet nd sptil forging ptterns. J. Nt. Hist. 36: 2211Ð2227. Ghosh, K., S. R. Jmmlmdk, nd R. C. Tiwri Semiprmetric Byesin techniques for problems in circulr dt. J. Appl. Stt. 30: 145Ð161. Gimenes, M., A. A. Benedito-Silv, nd M. D Mrques Circdin rhythms of pollen nd nectr collection by bees on the ßowers of Ludwigi elegns (Ongrcee). Biol. Rhythm Res. 27: 281Ð290. Gokce, A., L. L. Stelinski, L. J. Gut, nd M. E. Whlon Comprtive behvior nd EAG responses of femle obliquebnded nd redbnded lefroller moths (Lepidopter: Tortricide) to their sex pheromone components. Eur. J. Entomol. 104: 187Ð194. Guevr, R., A. M. Ryner, nd S. E. Reynolds Orienttion of specilist nd generlist fungivorous ciid beetles to host nd non-host odours. Physiol. Entomol. 25: 288Ð295. Gut, L. J., L. L. Stelinski, D. R. Thomson, nd J. R. Miller Behvior-modifying chemicls: prospects nd constrints in IPM. pp. 73Ð121. In O. Koul, G. S. Dhliwl, nd G. Cuperus (eds.), Integrted pest mngementñpotentil, constrints, nd chllenges. CABI Press, New York. Hvukkl, I. J., nd J. S. Kennedy A progrmme of self-steered turns s humidity response in Tenebrio, nd the problem of ctegorizing sptil mnoeuvres. Physiol. Entomol. 9: 157Ð164. Hsu, C. L Gender nd mting sttus differences in the ßight behvior nd dispersl of obliquebnded lefrollers, Choristoneur roscen (Hrris). PhD disserttion, Cornell University, Ithc, NY. Hull, L. A., G. Krwczyk, E. Bohnenblust, nd D. Biddinger Expnsion of n re-wide pheromone mting disruption pproch to control two mjor fruit pests in Pennsylvni orchrds. Penn. Fruit News 86: 43Ð50. Hull, L. A., G. Krwczyk, E. Bohnenblust, nd D. Biddinger Expnsion of n re-wide pheromone mting disruption pproch to control two mjor fruit pests in Pennsylvni orchrdsñyer 2. Penn. Fruit News 87: 50Ð61. Il ichev, A. V., L. J. Gut, D. G. Willims, M. S. Hossin, nd P. H. Jrie Are-wide pproch for improved control of orientl fruit moth,grpholit molest (Busck), Lepidopter: Tortricide) by mting disruption. Gen. Appl. Entomol. 31: 7Ð15. Jmmlmdk, S. R., nd A. SenGupt Predictive inference for directionl dt. Stt. Probbil. Lett. 40: 247Ð257. Jmmlmdk, S. R., nd A. SenGupt Topics in circulr sttistics. World ScientiÞc, Singpore. Kethler, F., D. J. Pree, nd A. W. Brown HCN: feeding deterrent in pech to the oblique-bnded lefroller, Choristoneur roscen (Lepidopter: Tortricide). Ann. Entomol. Soc. Am. 75: 568Ð573. Kennedy, J. S., A. R. Ludlow, nd C. J. Sunders Guidnce of ßying mle moths by wind-borne sex pheromone. Physiol. Entomol. 6: 395Ð412. Klrsfeld, A., J.C. Leloup, nd F. Rouyer Circdin rhythms of locomotor ctivity in Drosophil. Behv. Process. 64: 161Ð175. Knight, A. L., D. R. Thomson, nd S. D. Cockfield Developing mting disruption of obliquebnded lefroller (Lepidopter: Tortricide) in Wshington stte. Environ. Entomol. 27: 1080Ð1088. Kost, C., E. Gm de Oliveir, T. A. Knoch, nd R. Wirth Sptio-temporl permnence nd plsticity of forging trils in young nd mture lef-cutting nt colonies (Att spp.). J. Trop. Ecol. 21: 677Ð688. Lwson, D. S., W. H. Reissig, A. M. Agnello, J. P. Nyrop, nd W. L. Roelofs Interference with the mte-þnding communiction system of the obliquebnded lefroller (Lepidopter: Tortricide) using synthetic sex pheromones. Environ. Entomol. 25: 170Ð177. Li, S. Y., nd S. M. Fitzptrick Monitoring obliquebnded lefroller (Lepidopter: Tortricide) lrve nd dults on rspberries. Environ. Entomol. 26: 170Ð177. Li, S. Y., S. M. Fitzptrick, nd M. B. Ismn Effect of temperture nd toxicity of Bcillus thuringiensis to the obliquebnded lefroller (Lepidopter: Tortricide). Cn. Entomol. 127: 271Ð273. Lund, U Lest circulr distnce regression for directionl dt. J. Appl. Stt. 26: 723Ð733. Mdsen, H. F., J. M. Vkenti, nd A. P. Gunce Distribution nd ßight ctivity of obliquebnded nd threelined lefrollers (Lepidopter: Tortricide) in the Okngn nd Similkmeen Vlleys of British Columbi. Cn. Entomol. 116: 1659Ð1664. Mrdi, K. V., nd P. E. Jupp Directionl sttistics. Wiley, Chichester, United Kingdom. Milli, R., U. T. Koch, nd J. J. dekrmer EAG mesurement of pheromone distribution in pple orchrds treted for mting disruption of Cydi pomonell. Entomol. Exp. Appl. 82: 289Ð297. Morse, D. H Orienttion nd movement of wolf spiders Prdos lpidicin (Arnee, Lycoside) in the intertidl zone. J. Archnol. 30: 601Ð609. [NOAA] Ntionl Ocenic nd Atmospheric Administrtion U.S. climte t glnce. ( no.gov/o/climte/reserch/cg3/cg3.html). [NOAA] Ntionl Ocenic nd Atmospheric Administrtion Climtic wind dt for the United Sttes. ( Otálor-Lun, F., J.L. Perret, nd P. M. Guerin Appetence behviours of the tritomine bug Rhodnius prolixus on servosphere in response to the host metbolites crbon dioxide nd mmoni. J. Comp. Physiol. 190: 847Ð 854. Pfeiffer, K., M. Kinoshit, nd U. Homberg Polriztion-sensitive nd light-sensitive neurons in two prllel pthwys pssing through the nterior optic tubercle in the locust brin. J. Neurophysiol. 94: 3903Ð3915. Pree, D. J., nd W. P. Roberts Control of the obliquebnded lefroller, Choristoneur roscen (Lepidopter: Tortricide), on peches in Ontrio. Proc. Entomol. Soc. Ont. 112: 7Ð12. Pree, D. J., K. J. Whitty, M. K. Pogod, nd L. A. Bittner Occurrence of resistnce to insecticides in popultions of

9 April 2009 HSU ET AL.: EDGE EFFECTS IN THE DISTRIBUTION OF C. roscen IN APPLES 441 the obliquebnded lefroller from orchrds. Cn. Entomol. 133: 93Ð103. Presnell, B., S. P. Morrison, nd R. C. Littell Projected multivrite liner models for directionl dt. J. Am. Stt. Assoc. 93: 1068Ð1077. Reissig, W. H Biology nd control of the obliquebnded lefroller on pples. J. Econ. Entomol. 71: 804Ð 809. Roux, O., C. Gers, N. Telmon, nd L. Legl Circulr dispersl of lrve in the necrophgous Dipter Protophormi terrenove (Dipter: Clliphoride). Ann. Soc. Entomol. Fr. (Nov Scoti) 42: 51Ð56. Snders, C. J Flight nd copultion of femle spruce budworm in pheromone-permeted ir. J. Chem. Ecol. 13: 1749Ð1458. SAS Institute v SAS Institute, Cry, NC. Schtickzelle, N., nd M. Bguette Behviourl responses to hbitt ptch boundries restrict dispersl nd generte emigrtion-ptch re reltionships in frgmented lndscpes. J. Anim. Ecol. 72: 533Ð545. Shen, J.X., Z.M. Xu, nd E. Hnkes Direct homing behvior in the nt Tetrmorium cespitum (Formicide, Myrmicine). Anim. Behv. 55: 1443Ð1450. Stlleicken, J., M. Mukhid, T. Lbhrd, R. Wehner, B. Frost, nd H. Mouritsen Do monrch butterßies use polrized skylight for migrtory orienttion? J. Exp. Biol. 208: 2399Ð2408. Stelinski, L. L., J. R. Miller, nd L. J. Gut Cptures of two lefroller moth species (Lepidopter: Tortricide) in trps bited with vrying dosges of pheromone lures or commercil mting-disruption dispensers in untreted nd pheromone-treted orchrd plots. Cn. Entomol. 137: 98Ð109. Szentesi, Á., D. C. Weber, nd T. Jermy Role of visul stimuli in host nd mte loction of the Colordo potto beetle. Entomol. Exp. Appl. 105: 141Ð152. Toepfer, St., H. Gu, nd S. Dorn Spring coloniztion of orchrds by Anthonomus pomorum from djcent forest borders. Entomol. Exp. Appl. 93: 131Ð139. Trimble, R. M., nd M. E. Appleby Comprison of efþccy of progrms using insecticide nd insecticide plus mting disruption for controlling the obliquebnded lefroller in pple (Lepidopter: Tortricide). J. Econ. Entomol. 97: 518Ð524. Willis, M. A., nd T. C. Bker Effects of intermittent nd continuous pheromone stimultion on the ßight behviour of the orientl fruit moth, Grphli molest. Physiol. Entomol. 9: 341Ð358. Witzgll, P., A.C. Bäckmn, M. Svensson, U. Koch, F. Rm, A. El-Syed, J. Bruchli, H. Arn, M. Bengtsson, nd J. Löfqvist Behviorl observtions of codling moth, Cydi pomonell, in orchrds permeted with synthetic pheromone. BioControl 44: 211Ð237. Yetmn, S., nd G. S. Pollck Proboscis extension in the blowßy: directionl responses to stimultion of identiþed chemosensitive hirs. J. Comp. Physiol. A 160: 367Ð 374. Received 25 Februry 2008; ccepted 17 December 2008.