Five trap designs, the Pherocon 1CP, a triangular trap, dome trap, double cone trap and Kendall trap were evaluated for capturing the western spruce budworm, &lt;i&gt;Choristoneura occidentalis&lt;/i&gt; Freeman, both in a laboratory-based windtunnel and in an infested stand. Neutral density smoke tests showed the effects of orientation to wind on plume formation as well as highlighting plume structure around larger traps. Moth capture rates in the windtunnel did not always correlate with capture rates under field conditions

Angerilli, N. P. D.

McLean, J. A.

English

Journal of the Entomological Society of British Columbia

10 J. ENToMol. . Soc. Bnrr COI.U\fBIA 8 1 (1$)84), DEC. 31, 1084 WINDTUNNEL AND FIELD OBSERVATIONS OF WESTERN SPRUCE BUDWORMI RESPONSES TO PHEROMONE-BAITED TRAPS3 N. A NCE RILLFANDJ . A. M c LEAr-.: Faculty of Forestry University of British Columbia Vancouver , B.C. V6T lW.5 ABSTRACT Five trap designs, the Pherocon l C P, a triangular trap , dome trap, double cone trap and Kendall trap were evaluated for capturing the western spruce bud-worm , Choristoll eura occidellialis Freeman, both in a laboratorv-based windtun -nel and in an infested stand. Neutral density smoke tests showed the effects of orien-tation to wind on plume formation as well as highlighting plume structure a rou nd larger traps. Mot h capture rates in the w indtunnel did not alwavs correlate w ith capture rates under field conditions . ~ INTRODUCTION Pheromone-ba ited traps have proven useful for monitoring many species of insects and are often in-tegral parts of pest management programmes (Ken-nedy 1981 ). Such traps are most useful if they are consistent in their catches and refl ect the rela tive abundance of the insect being monitored. Several designs of sticky traps have been evaluated against the spruce budworm , Chorislurl eura JumiJeralla (Clem .). (Sanders 1978: Houseweart et al. 198 1). Omnidirectional high capacity traps have also been tested for moths (Steck and Bailey 1978: Struble 1983) with several designs recently developed and tested specifieallv against the spruce bud worm (Ramaswam y and Carde 1982; Kendal el al. 1982). One difficult y with testing traps in the field is determining how many insects were attracted but not captured. That is, it is difficult to know how "efficient"· a given trap design is except relative to other traps. The objective of this study were to observe and measure the absolute efficiency of several trap designs to attract and capturc male western spruce budworm (WSBW) C . occidentalis Freeman, under laboratorv conditions in a windtunnel: to rela te this efficiency to the size and shape of emitted pheromone plumes; to make predictions, based on these results, of the field efficiency of the tested traps: and to test the laboratory predict ions in the field . MATERIALS AND METHODS A 4.88 m long windtunnel with 1.2 m square cross section was built and calibrated for wind speeds from 0 to 1.4 m s ' The front side and top of the tunnel were of clear acrylic plastic while the back and bottom were fir plywood. Air was drawn through a smooth curve entrance and double screens in order to produce a laminar windflow . Measurements of wind speed demonstrated uniform + CllU r~'i tolle'Jra ucddel ltalis; Lepidoptera : Tortricidae . zPrescnt addres.'i: A~ricultllrf' Ca nada, Research St ation. SU IIl -merland. British Columbia VOH I ZO . JConlribution No . (iO.:;. Hesea rch Station. Summerland . cross tunnel velocities and the presence of a 2 . .5 cm still air boundarv laver which heloed to minimize pheromone cont~mi~ation of the ;vindtunnel. The end of the tunnel was a lso screened to prevent escape of insects. Quarter sections of the acrvlic panels were hinged at the front and rear of the t'un-nel to facilitate access for test ma terials and insects. Air was drawn from the tunnel and expelled to the outside of the building. All tests were conducted a t 0 . .5 m s· '. ~ The traps tes ted in the tunnel were the Pherocon l CP (Zoecon Corp .), a triangular trap (Cory et al. 1982), a double cone trap , a dome trap and the Kendall trap (Fig. 1). The first two traps rely on sticky inner su rfaces to trap attracted insects while the last three were no-exit type non-st icky traps. In order to visualize the pherom one plume emitted from these traps , an approximation was made by usin g titanium tetrachloride neutral density "smoke" . The TiCI. was released from ha lf-filled one dram glass vials with a 2 cm long string w ick to act as an evaporative surface. The vi al of TiCI. was positioned inside each trap at the same point as the pheromone dispenser. Each trap was tested to determi ne the smoke plume (and so to infer the pheromone plum e) from the trap in line with the wind (180 °), crosswind (90 °) and at an angle to thc wind (4.5 °). The plum es were recorded on pan-chromatic film and later sketched. \Vestern spruce budworm from the non-diapausing strain kcpt at the Pacific Southwest Forest Range Experiment Station at Berkele,·, CA, were reared on artificial diet (BioServ® 9769). Pupae were placed into individual containers and kept in a light dark regime of 16 and 8 h with daw n occurring at 2400 h and dusk at 1700 h . Adults were kept under the same regime until three days old when they were used once between 1300 hand 1800 h in /light tests. After test ing, the moths were kept for a further 24 h. The dat a were retained only from those insects that survived. . The synthetic WSBW pheromone, a 92:8 blend of (E) and (Z)- II-tetradecenal (E , Zll-14:Al ), was dispensed from 10 Ji L glass capillaries conta ined in J. E:\TO~f()l.. Soc. I3l\rr . COl.uIIlI.-l 81 (l!)8~). DEc. 3 1. 1 !)8~ II Fig. I . Traps evaluated in the UBC windtunnelusing TiCI. neutral densih' smoke: traps A-D a lso tested for effici ency in capturing WSBW when baited with pheromonc: all traps tested in the fi eld. A. Pherocon ICP trap, B. Triangular trap , C. Dome trap, D. Double cone trap. E. Kendall trap. an open I dr. glass vial. The pheromone test pro-cedure consisted of taking the males out of the con-trolled environm ent rearing chambers 0.5 h before the beginning of test ing and the pheromone- loaded capillaries out of refri ge ration I h before testing. The pheromone-bai ted trap was placed in the tun-nel entrance as described for the trap smoke tests. Males were released individually at the opposite end of the tunnel onto a circula r glass platform (diameter = 20 cm ) so pos itioned that the moth was in the estimated centre of the pheromone plume . Time-to-flight initiation (latency) , t im e- in-flight . and ti me-to-capture (where appropriate) after reaching the pheromone source, werc recorded in seconds. Males were also scored as being responders or non-responders . Typically, a responder faced in-to the wind with the longitudinal body ax is in line wit h the wind direction , exhib ited pre-flight wing-fanning, and took-off into the w ind ; the resulting fli ght line was a zig-zag upwind in the estim ated plume region towards the pheromone source on which it landed and exhibited post-flight or pre-mating walking and wing-fanning. A non-responder usuall~ ' failed to fl y although it sometimes faced into the wind or took off downwind. Traps were tested using three capilaries of E,ZII-14:Al as this was shown to produce 80 % responders, a short latencv ( x = .5 .75s , n = 10), and a fast fligh t time (x = 33 .9s , n = 10). The three directional traps were tested at the three trap-to- wind angles p reviously mentioned . The com-parat ive tcst of the Pherocon ICP , triangular (apex down), dome, and double cone traps was run as a 4 x 4 lat in square in which each trap was tested dail y for 4-days using fi ve individu ally released moths per trap. The test was re-randomized and run a second tim e. To test windtunnel predictions of the relative effi-ciencies of the previously tested traps, a 6 x 6 latin square design experiment was established near 12 J, E\:To\ IOL SOC.I:l I!1 T , C0 1.1 ;\ I RI A II I ( 1984), DEC. 3 1. 1984 ) ... A D .:$.,. B E . ,'-:".it ~i : ' ~~~? ;' ' ~.' C F Fi g, 2, Tie1., smoke plum es from (\, '0 sti ch traps : Triangular trap sho\l 'ing A, side , 'ie \l' at 180 ° to \I'ind, B, lopl' icw at 90 ° to w ind. and C top , 'ie\l ' at 45 ° to \I 'ind : a nd Ph erocon I CP trap showing D , top "ic\l in line \I'itlt wind. E, side "i l' \I ' in li ne \I 'ith \I ' inc! and F, top , 'iew a t -15 ° to wind , Oregon Jack Creek. B,C, in an area of moderate to high "VSBW infesta tion , The fifth and sixth traps wcre the t ri angul ar trap with the apex up rather than dO\l'n and the Kenda ll trap (Kendall c( ai , 1982) , The experim ent \I'as initiated on the evening of 16 Au gust 1982 and Ill oths were cou nted a nd the traps empt ied at mid -day on 17 and 18 Augus t 1982, J, E"To.lloI..Soc.I3HIT COl.L',\ITlI.ISl ( 1 98~ ). OLe .'l l . 198·1 13 RESULTS A"'D DISCUSSION The tr iangular trap produced a re lat i\ 'ek dense and stabl c plume when orie ntated in lille \~' i th the wind (Fig, 2A) , The trap was alwa\'s tun nel-tt'sted apcx do\\'n, ho\\ 'c\'e r , and afte r t\I'O o r three males had struggled in the sti ck\ ' coatin g at the trap's en-t rance it beca me less sti ck\ ' dil l' to w ing sca les coat ing the st ich smface, Later, mal es we re somet imes seen to enter the trap. conti nile wing fannin g a nd eventuall! ' reemerge from the t rap and fl v awa\', \Vhen oriented across wind. some smuke \\:as stili released (Fig, 2fl ). and at ~ ,5 ° to the \\ind a broader , less densc plume \\ 'as produced (Fig, 2C), When the Phcroco n l CP trap was in line \\ith the wind it produced a broad (Fig, 20). dense (Fig, 2E) and easih'. tracked plu me, The side \'iew (Fig, 2E) shows th at there was s(nlle "backwash" of thc plullle A ~ r'\ r-r i- . B and males were of len ob"ern :d walk ing and fannin g in this area prior 10 ente ring thc trap, A les" dense plum e \\'as prodllced when the trap \\ 'as at ~,S u tn the w ind (Fig, 21-') , W lw n set Ollt at gO to the wind. no \'isible smoke plum e \\'as produced, Th e dO nl e trap prod ll ced a narro\\' plullle hut had thc ad\'antage of producing it dirt'e tk fro ll! its open ing (Fig, .'l A). and responding mules norrnalh' did not find it difficult to find and e n[('r th E' trap , The novel des ign of the trap \I'as based on air pressure d iffcrences bcl\\'een iLs bottoll1 and top caused by the longer tnl\'el path of air flO\\ 'in g (1\'e r the top relat i\'e to a ir fl ow ing under the bottoll1, The pressure d ifkrence caused air to flow th rollgh holes in the bottonl of the trap \\ 'hic:h \\ 'as equipped with onc-\\'a! ' flap \'ah'es into tilt' traps' inter io r \\'here it beca me pherolllone laden ancl then em erg· ... . --..... ", c o Fig, 3, TiCI, smoke plumE'S from A, Dome traps . B, OO ll ble cone trap. C. Kenda ll t rap (top \' ie\I') . and D, Kendall trap (side \'ie\\ ) , 14 J, Ei\TO,\ IOI. Soc. BI1IT C()I.U~IB I A 8 1 (1084), DEC..31. 1984 TABLE 1. Compa rison of mal e WSEW responses to pheromone baited traps oriented at 180 °,4.5 0 and 90 0 to the windOow in a \\ 'indt unnel (n = 10), Trap Orientation Latency Time in Time to Number des ign windflow (0) time (s) flight(s) capture(s) cap tured Tr i angular 190 5 . 2 1 24 .8 a 55.37 a 8 a 45 3 . 1 a 17 . 5 a 33 . 44 a 9 90 2 .9 a 18 . 1 a 48.12 a 8 Pherocon lCP toao 1. 8 a 14 . 9 a 21. 8 a 10 45 2 .4 a 24 . 7 a 93.0 b 8 90 2 . 5 a 27 . 5 a 128.1 b 7 Double cone HO 15.1 a 58 .9 a 84.3 a 6 45 14.5 a 20 . 5 a 86.6 a 5 90 10.1 a 18 . 9 a 139.6 a 5 1 fo llowed by le tter within Me ans the same columns a nd within trap t ypes are not s ignif ican t ly diffe rent (Student Newman- Keul s , P < 0 . 05) . TABLE 2. Mean number of male WSRW caught b\' four trap designs oriented in line \\'ith the \\'ind in a w ind tunnel experiment (n = .s per replicate, 4 replicates run in a latin sCJ uare randomization con-fi gurat ion) , The experiment was run twice, Mean catchl Trap Run 1 Run 2 Combined Pherocon lCP 4.75 a 4.25 a 4.50 a Triangular (apex down) 3.50 ab 2 . 50 a 3.00 b Dome 3.50 ab 3 . 25 a 3.38 ab Double cone 2.00 b 2.75 a 2 . 38 b lMeans followed by different l et t ers are significantly different (Student Newrnan-Keuls, P < 0.05). J. E:--:TmIOI.. Soc. BnlT COI.U~lmA HI ( 1 9H~ ). 01':(; 3 1. H)8~ 1.5 TABLE 3. \1ean number of male \\'SB\\ ' eau!!ht b\" six traps of fh 'e designs dllring two ni ghts in 1982 nca r Oregon Jack La ke. B.C. Mea n catch ± s.d. 1 Trap July 16/17 July 17/18 Pherocon lCP 26.5 ± 11. 7 a 44.3 ± 21.1 a Triangular (apex up)2 15.3 ± 10.0 b 39 . 7 ± 13.3 a Triangular (apex down) 13.3 ± 4.4 b 26 . 2 ± 5 . 4 b Kendall 3.0 ± 2 . 7 c 16. 3 ± 8.8 bc Doublc cone 2 . 5 ± 1.5 c 3.8 ± 1.5 c Dome 0 . 3 ± 0 . 5 c 0 ± 0 c Total moths captured 366 782 1 to Xl (X+l) to analysis of Data transformed = log prior variance . Means not fol lowed by the same le tter are significantly different (Student Newman- Keuls t est , P < 0 . 05) . 2 Two of the six traps became inoperative during the first night, but were repaired for the second. ed through a single hole in the top of the trap. The double cone trap produced a much broader plume \\'ith much back-flow O\'er the outside of the trap (Fig. 313) up to the cen tral co nnec ting ring . This backflo \\" could result in considerable contamina-tion of the outside of the trap . \Vhen male \vSH\v landed in thi s area they \\"miid \\"alk and continue to \\"ing-fa n for an ex tended period a nd occasionalh" enter the trap if the\" enr:o unt ered the entra nce . The Kenda ll trap generated a broad plume (Fi!!. 3C ) which also may have contaminated the outside of the collecting jar (Fig . 3D). Certainh" m a m ' males fa nned ex tcnsi\"e!y o\"er the outside of the collecting jar withou t locat ing the entrances to the trap. Moths also readily \\"a lked ou t of this trap rather than dropping in to the collecting jar. In the first seri es of pheromone experiments in the \\"indtunnel (Table 1) it was seen that the triangular trap eapturedm ore tha n 80 'k of the test insects and had low latency periods which confirmed the ade-quate plu me formati on seen in the tunnel. These resu lt.s were consistent for a ll trap orientations tested. Results for the Pherocon I C P trap in line with the \\"ind were the best obtained. wit h the smallest latency tim e. least time in fli ght , fastest ti me-to-capture. and all the male \VSHy\, captured . This trap was sensit i\'e to cross-wind orientations with less dense plume formation (F ig. 2F) \\"hich resulted in extended periods to capture (T a ble 1\. The plume from the double cone trap was con-sidcrabh' enlarged w hen the trap was oriented in line with the wind. The diffuseness of the plume by the time it crossed the take-off platfo rm might ac-count for the increasedlatenc\" times (Table 1) . The long time-to-capture probably refl ected the difficul -t\· of the male \vSBW in locating the entrance hole "in the perforated end screen in the trap (Fig. Id). The Pherocon ICP was consistentl y the most ef-fective trap in the windtunnel (Table 2). The results suggested that the dom e trap was a promising des ign and that the double cone trap was consistent-ly ineffi cient. In the fi eld experi men t , the Pherocon I CP trap consistenth- captured the most male 16 J. E1'TO,\ tOL Soc. BHI T . CO L U\tIlIA 8 1 (1984 ) . D EC. 31, 1 98~ \,vSBW (Table 3) more than dOllbl e the numbers caught in the best high capacih' trap. The one night tcs ts did not really test the high capacity trap fu nc-tion although it is clear that none of the high capaci -tv designs wcre as effective as th e sti ch traps. T he tri a ngul a r trap captured more moths w hen the apcx of the trap was uppermost (Table 3). This suggested tha t the large r landing platform may ha ve provided an important additional entrapment area. The grea test disappointm ent , was the poor shO\\'ing of thc dome trap. Smoke tests showed that wind pat-terns within the stands \\·here trapping was carri ed out were va riab le and of a much lower veloc it \· than the 0 .. 5 m S I windspeed used in the windtunnel to ca librate and tes t the trap . The results of this stud\' ha\'e show n that smoke tes ting of traps in a ;vindtunnei can provide valu able information on the in tegrit y of plume for-mation and shape in rela tion to orientation to the wind. Pherom one-baited traps can be evaluated as to tbeir cfficiencv but these results will not necessarih' be rene~ted by ca tches in the same traps under fi eld cond itions. The currenth' used t ria ngular trap appears to be as effective as anv other design at low popu lation levels before the trapped moths saturate the traps. HEFE HENCES COl,\, . H . T . , C. E. Dalerman . C. I). Daves, Jr ., L. L. Sower, H. F. Shepherd and C. J . Sanders, 1982. C hemistry and field evalua tion o f the sex pheromo ne of western spruce bud\\'orm , C horistoneura oc-cidentalis , Freeman . J . C hem. Eeol. 8:339-350. Houseweart , M . W. , D . T. Jennings and C. J . Sa nders. 198 1. Variables associated w ith pheromone lraps for monitor in g spruce budworm populations (Lepidoptera: Tortricidae). Can. Ent. 11 3:527-537. Kendall , D . M. , D. T. Jennings and M . W. 1I0usewearL 1982. A large-capacit\· pheromone trap for spruce budworm moths (Lepidoptera: Tortri cidae). Can . Enl. ]] 4:46 1-46.3. Kennedy, J . W. 198 1. Practical applicat ion of pheromones in regulator\' pest management programs. In Mitchell , E. H. (cd) Management of Insect Pests w ith Sem iochemicals - Concepts and Practi ce. Plenum Press N.Y . pp. 1- 12. HamaSWalll\', S. B. and R. T . Carde. 1982. :-\onsaturating tra ps and long- li fe att ractant lures for monit or-ing spruce budworm ma les . J . Econ . En lomol. 75: 126- 129. Sanders, C. J . 1978. Evaluation of sex att ractant traps for monitorin g spmcl' bud\\'o rm populations (Lep idoptera: Tortri cidae) . Ca n . Ent. 110:43-50. Steck. W. a nd B. K. Baile\·. 1978. Pheromone traps for moths: eva luation of cone trap des igns and des ign pa rameters. Environ . Entomol. 7 :~~ 9-~.5.5. Strubl e. D . L. 1983. Pherom one traps for mon ito ring moth (Lepidoptera) abu nd ances: evaluat ion of eone-ori fi ce and ornn i-direction a l designs. Ca n . En!. 11 5:59-65. 

Windtunnel and field observations of western spruce budworm responses to pheromone-baited traps

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Windtunnel and field observations of western spruce budworm responses to pheromone-baited traps

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Journal of the Entomological Society of British Columbia