J. E.Yl'OMOl.. So,. BLOT. COI.I : ~I[HA, 64 (1~jti7). AI',;. l. lliti7 1 ~

References Green, G. W. 1962. Low winter temperatures ane! the European pine shout moth, Rhy­ acionia buoliana (Schiff.) in Ontario. Can. Entulllol. 9-1,:314 -336. Green, G. W., and P. J. Pointing. 1962. Flight ane! clislwrsal of the '

RESISTANCE TO ORGANOCIILORI~E I'\SECTICIDES IN THE TUBER FLEA IlEETLE. 1TIJf;RIS GE~T. (COLEOPTERA: CHRYSOI\IEUDAE). I~ BRITISH COLlJ\IlUA I F. L. BANHAM and D. G. FINLAYSON ABSTRACT Laboratory and field e"pl'L"iments sh(mcd that Epitrix tuberis Gent. had developed strains that\\ ere hi ghl.\ resistant to dieldrin and less so to DDT Both adults and lan'ac \Icre rcsi,(ant to thl' c:\"(~ lodi('n e insecticides. Strai'ns resistant to cycloe!icnl'.s Ilere ccntercd in the Salmon Arm and Vernon areas. Strains resistant to DDT had a lI" idN rangc and II'ere present as far north as Pavilion. All tuber flea tested in the province \\"cre highly susceptible to cliazinon ane! prcsumably 10 othl'r organophosphorus compounds. INTRODUCTION cyclodiene insecticides to control E. tuberis in Clackama.s County, Oregon, In the southern interior of British (Morrison, 1962). DDT was included Columbia the tuber flea , because it was used in British Colum­ Epitrix tuberis Gent., has been con­ bia as a foliar t rea tmen t against this trolled effectively since 1953 by incor­ pest after 194.8 following inve.stiga­ porating into the soil the cyclodiene tions by Finlayson and Neilson organochlorine insecticides: aldrin, (1954); it remains an altRrnative to chlordane, dieldrin and heptar:hlor soil t reatments with the cyclodienes. (Banham, 1960). These insecticides The first suspicion that resistant gained a ready acceptance and were [i' tuberis were present in British widely used because one lo w-cost ap­ Columbia camR at harvest in 1964, in plication gave broad-spectrum insec­ the Salmon River Valley. Six growers ticidal effectiveness. In 1963, labora­ reported exces.sive larval tunnelir.g tory tests were conducted to deter­ damage in their potatoes in spite of mine the susceptibility of E. tuberis the use of aldrin or dieldrin at recom­ to dieldrin and DDT. Dieldrin was mended rates. This paper reports the incl uded because of the reported fail­ initial laboratory experiments in 1963 ure in 1960 of soil applica tions of the and furthRr tRsts in 1965. Data are re­ ported also from a field experiment in 1- Contribution 1\0. 214 , Research Stations, Re­ the Salmon River Valley in 1965 to ~earch Branch, Canada Agriculture, Summerland, and No. 124. Vancouver. British Columbia. confirm the occurrence of resistance. 1 ~

MATERIALS i\ N D METHODS fitteel to the inside of a 40x100 mm La/)orato7"Y E,Tpcri ll!cn ts cardboard tube with screened ends. Larvae of thL" sper'ies were not In 1965 the only exposure cage u."ed for the .'iu .~ceptibi lit y tests be­ used was the W.H,O. Test Kit, a cause they ~1l'e extremely small and transpar ent plastie cage with s creen­ difficult to l'l~ ar, They D re root and ecl ('nels, The impregnatecl papers used til be r fecclcl',~ tha t desi('ca te rapicil:' inclucleel W.HO, dieldrin papers a s 011 exposure, Fieici-collf'ctecl second cle.<.;cribed abovc a nd also W.H,O, DDT g'encratioll :lclulb we)'c used becrlll.<;c paper.') with concentrations of 0,0 , 0,5 . of tl1C'il ilarcliness. abundance. uncI 1.0, 2,0, and "]',0'; DDT in Risella oil. cac;c of hallc!iing, The sex ratio i" 1:1 In aclditioll. two series of papers pre­ (Neil.<;on and Finlay."on, 1953). but pared at the Vancouver Research lhC'l'e ~U'e ;10 (' x l erna! sex cllaraeter i.<; ­ Station were used: the fir.st included tic.<; . ami no attC'mpt was made to (,ollccntration.~ oJ 0,0 , 0,125, 0,25, 0.5, determine differences in male and fe­ 1.0. 2,0. and 4,0'; clieldrin in a 1: 1 male ,';Hsceptibility, Collect ions were mixtUl'C' of Risella oil and trichloro­ macle a L Llw jJeal< of el1wrgence from ethylene: the ,~ecol1 d inclmlecl 0.0, nine major pot a to growing area.'; in 0.;)625, 0.125, 0.25, 0,5 anel 10% elia­ H)63 and from eig-llt area." in 1965 zi non in a 1: 1 mixture of acetone and (Fig, 1.) 1'11(' bcetles were hcld at 4 eorll oil. The papers were prepared by to 10 "C in .<; eJ'f'en-loppecl gla.<;s j~1l' .,; applying uniformly 2,0 ml of insecti­ and providecl wiLll f)'csl1 . uncontamin­ Gide solution to a 12x15 cm sheet ot atecl potato foliag'e, Prior to testillg. Wl1atman No, 1 JilLer paper placed on beetles from each area we)'e acclima­ a horizontCl I plane of p oints, Arter the Lizecl in screened cages at 22 C Active more volatile ;; olvents evaporateel, beetles were removed fro l11 the cage.'i each paper was attached to a cord by with an a.<;pirator. anae <; tl1etizecl with a paper clip and hung to dry for at CO2 . and helcl temporarily in a 150 Il'a .~ t 24 hours before use. 111m I3iicl11WI' fUllllel ullder a con­ Tile toxicities of laboratory - and tinuous fl ow of 111C' ga.';, Anaesthetizeel W.H,O,-prepared die 1 d l' i n papers beetles WCl'l trall,<;ferred with a iJru.<-;ll were founel to be comparable when or 1'oreep.~ to tIl e expo.~ll re eage.'), su.,ceptible an(l resistant strains of In 19G:) impregna t eel paper." from beetles were exposed to eaeh series, two sO\lrce.~ were used: the lVlaec!onald Each r eplicate consisted of ten Tes t Kit and the W.H,O, Test Kit2, beetles per eoncenLration of insecti­ The Maeclonald expo.sure cage con­ cietl', Depending on the number of si-steel of a c8rdboard Dixie cup with beetles availal)le, the number of repli­ a silk sereen lid. a plastic ring, and an eate.s per collectioll area varied from impregnated expo,sure paper that one to three in 1963 anel from one to covereel the ;-;ielc.,; and bottom of the five in 1965, When there were not cup, This exposed the beetle.s to con­ enough beetles from one location to taet with tl1e impregnated paper on complete a replication, those remain­ 811 but the top ..<.; ereened surface of ing were combined with beetles of the cage, The concentrations of Llle .similar susceptibilities from three or imprpgna tecI paper.~ used were: 0,0. m ore areas. 0.25, 0,5. 1.0, 20. allCi 40' ! DDT in The caged beetles were exposed to Risella oiL The V;,H,Q, pap e r.s the insecticides in a cabinet at 22"C (W,HO.. 1960) Kere impregnated :1nd 1'5'; relative humidity, Exposure \\'itll: 0,0. 0,1, 0.2 , 0.4, f),S. l.G, and perioels ranged from one to four hours, 4.0'; elieldrin in Risella oil. Eacl1 was Knockdown, or inability to walk nor­ 2 TIll' l\i;t('donald Test I,- it \\:t:--. ::-iu pplipd hy mally, was recorded at the enel of the Prof. F. O. ;\Torri."oll" Dept. of Entol1lolpg.'" and Plant I'atholog.\. i\'iacdonald College. StL', ~\Ilnl' de exposure, The beetles were then 13ell€\'Iw. P,ll,; the W,H,O, Test Kit h~' Ilr, B, Pal, transferred to clean holding t ubes Di \'i-.;io l1 of' 1'~Il\"jrO!ll1lellt;il Health . \\'nrld Jlt'alth ()r.l!;uli/:l1 iOIl. Gpneva. eontaining fresh, uncontaminated .l. ]!;.\TOM(l I.. 19 SOl. BHIT. C OLl '~ l ilIA. 64 ( 1967). AUG . I, ) 967

BRITIS H

COLUMBIA

( PENT IC TON

~~~ ...;

Fig. I.-Potato growing areas in British Co lumhia \\·here tuber tuberis fl ea heetles. Epitrix Gent., were co llected: (1 ) 1963; (21 1965; and (1,2) 1963 and 1965. potato foliage and returned to the to a depth of 3 to 4 inches (7.5 to 10 cabinet. Mortali ty coun ts were made cm) by discing. Two samples of tub­ at the end of a 24-hour recover y ers were taken from the treated and period. Beetles unable to walk were un trea ted plots: the first, 84 days counted as dead. after plan ting, was to determine the In these tests, beetles from a given da mage inflicted by first generation locali ty were considered to be resist­ la rvae; the second, 147 days after an t if th e slope of the dosage-mortal­ pl a nting, was to determine the sea­ ity curve was flat, or if a ten-fold .sonal damage by first and second increase in concentration resulted in gen eration larvae. To assess damage, less tha n a 20 % increase in mortality. a s ubsample of 25 tubers of a mini­ Popula Lions showing an increase in mum diam eter of 1.5 inches (4 cm) mortality greater than 20 % but less was selected from each plot sample. The tubers were peeled to a uniform than 90 0 e at this increased concen­ tration, were defined as tolerant ; depth and the number of larval tun­ those wit h increases greater than nels recorded. 90'; were defined as susceptible. The RESULTS da ta were averaged. Corrections for Laooratory Experiments natural mortality were made using Knockdown and mortality counts Abbott's formula (Abbott, 1925) . of beetles exposed to DDT, with minor exceptions, were highest at the long­ F ie ld EJ:periments est periods of exposure. For any given In 1965 an experimen t to compare concentration and expos ure, knock­ aldrin-treated and untreated plots down co un ts paralleled the mortality was set out in the Salmon River Val­ counts but at lower levels. ley (Fig. 1). The plots, a pproximate­ In 19 63 (Table 1) there was little, ly 24 yd 2 (22 m 2), were replicated if an y, resis tance to DDT a t Chase, four times in randomized blocks . Al­ Quesnel, or Soda Creek. However, at drin 20 ' ( emulsifiable concentra te, Al exa ndria , Armstrong, Cache Creek, was sprayed on th e soil , at the recom­ Ka mloops and Pavilion the results in­ mended ra te of 4 lb. toxicant acre dicated the first s tages of resistance. (4.48 kg h a) . prior to planting. The There was little evidence of resistance a ldrin was incorporated in to the soil to dieldrin.

TABLE l. - Su s ceptibili t ~ · to DDT and dielrlrin of adult E. tuberis in British Columhia, 1963. Location Exposure (hr.) Mortality (%)1 at 24 hr. DDT (%) 0.25 0.5 1.0 2.0 4.0 Alexandria 2 10.0 30.0 10.0 30.0 60.0 Alexandria 4 20.0 50.0 50.0 90.0 100.0 Armstrong 4 50.0 50.0 90.0 80.0 80.0 Cach e Creek 4 50.0 0.0 0.0 80.0 100.0 Chase 2 50.0 60.0 60.0 70.0 100.0 Kamloops 2 170 27.0 37.0 50.0 67.0 Kamloops 4 40 .0 50.0 65.0 90.0 100.0 Pavilion 2 10.0 10.0 10.0 15.0 30.0 Quesnel 2 22.2 11.1 100.0 Soda Creek 2 20.0 40.0 30.0 100.0 100.0 Co mpos it e2 4 88.9 66.7 88.9 88.9 100.0 Dieldrin (%) 0.1 0.2 0.4 0.8 1.6 4.0 Alexandria -l 60.0 80.0 100.0 100.0 100.0 Kamloops 1. 5 10.0 30.0 60.0 70.0 90.0 100.0 Kamloops 2 0.0 75.0 62 .5 87.5 100.0 100.0 Kamloops 4 20.0 70.0 100.0 100.0 100.0 100.0 Pavilion 1.5 3.0 13.0 37.0 80.0 97 .0 100.0 Co mposite2 2 30.0 0.0 70.0 90.0 90.0 100.0 I A\'erage corrected by Abbott's formula (1925) ~ Armstrong, Kamioops and Oyama. .T. i'; .\T()\lI" .. S,,, 111<1T . ('01 .1 .111:1 \. 64 (l!Hii l. ,\ , " " I. 1 '1 0' 21

By 1965 (Table 2) there was strong anclria, Chase. G ran d Forks and evidence of DDT-resistance at Lav­ Kamloops were still susceptible. The ington and Salmon River. Of the beetles with high DDT and dieldrin beetles from eight potato - growing resistance, from Lavington and Sal­ areas, those from Lavington and Sal­ mon River, were highly susceptibl2 mon River also exhibited a high re­ to diazinon. A composite sample of sistance to dieldrin, probably ap­ beetles from Alexandria, Cache Creek, proaching a homozygous - resistant Chase, Kamloops and Pavilion wen~ population. Beetles from Cache Creek alw equally susceptible. and possibly those fro m Pavilion Field Experiments showed less resistance, or a heterozy­ At Salmon River, tuber sample.'; gous population. Beetles from Alex- taken 34 and 147 days after plantinf';

TABLE 2. -- Susceptibility to DDT. dieldrin, and diazinon of adiJlt E. tuberis in British Co lumbia. 1965. DDT(%) Location Exposure (hr.) Mortality (%)1 at 24 hr. ~5 1.0 2~ 4.0 Lavington 1 0.0 10.0 10.0 10.0 Lavington 2 0.0 0.0 10.0 200 Salmon River 1 0.0 0.0 5.0 15.0 Salmon River 2 10.0 10.0 00 200 C(i mposite ~ 1 0.0 23.5 0.0 58.8 Composite~ 2 0.0 10.0 0.0 60.0 Dieldrin (%) 0.125 0.25 0.5 1.0 2.0 4.0 Alexandria 1 :19.5 8Ll 97.3 86.5 100.0 100.0 Cache Creek 1 30.0 500 450 50.0 70.0 65.0 Chase 1 90.0 95.0 lOtl.O 100.0 lOOO 100.0 Grand Forks 1 73.9 100.0 100.0 100.0 lOO.O 100.0 Kamloops 1 70.0 800 90.0 lOO.O 100.0 100.0 Lavington 1 0.0 0.0 0.0 00 5.0 00 Pavilion 1 30.0 40.0 600 90.0 90.U 100.0 Salmon River 1 3.1 0.0 3.1 0.0 05 6.1 Diazinon (%) 0.0625 0.125 0.25 0.5 1.0 Lavington 1 60.0 75.0 900 lOOO 100.0 Salmon River 1 65.0 90.0 90.0 95.0 1000 Composite~ 1 80.0 90.0 90.0 90.n lUO.O 1 Average corrected by Abbott's formula 11925) ~ Alexandria, Cache Creek, Kamloops and Pavilion. from untreated and aldrin - treated level of resistance in an plots showed li ttle difference in the when the range of concentrations of amount of larval feeding damage. the test insecticides is restricted by This con firmed the labora tory evi­ the availability of Iield - collected dence for cyclodiene resistance in E. specim ens. The level should be de­ tuberis. Average numbers and ranges termined by direct comparison of the of larval tunnels per tuber from al­ LD 50 of the suspect strain with that drin-treated and untreated plots were of the normal sus c e p t i b I e strain as follows: (Brown, 1953). 34 DAYS Average Range From the results obtained in 1963, aldrin - trea ted 56.6 11-209 beetles from Pavilion were re.<;istan t untreated 57.7 9-139 to DDT while those from Alexandria, 147 DAYS Armstrong, Cache Creek and Kam­ aldrin - trea ted 229.1 27-434 loops were tolerant. All the beetles untreated 137.6 7-536 frem the nine location.') sampled in DISCUSSION 1963 were susceptible to dieldrin. Sus­ It i.~ difficult to determine the pected resistance at Salmon River in 22 .J. l~0: TO~I O I. . Scw. RBIT. C OI.U MBI A . 64 (1967). AUG. 1, 1967

1964 wa.s confirmed by la boratory a r eas where exten sive use of soil­ tests in 1965. The sam e tests confirm­ incorporated c y c 1 0 die n e insecti­ ed resis tance a t La vington. The fail­ cides commenced in 1953 and 1954 ure of a soil-incorpora ted application superseding foliar applications of of aldrin in the field experiment DDT. Use of cyclodiene insecticides, showed that the larvae were resis tant known to be persistent (Banha m, also. Soil treatments of aldrin or 1961) , r esulted in accumulations of other cyclodien e insecticides norma l­ insecticida lly a ctive residues in the ly prevent da mage by killing the soil. SiIl ce E . t uber is is virtually host n ewly emer ged 1st , 2nd a nd on occa­ specific, the whole popula tion a t one sion, 3rd ins ta r la rvae while they location was continually exposed to search in the soil for pota to roots or broa dcast or band applica tions of the tubers . It was demonstra ted that eurrent yea r plus the accumulated these popula tions had cross-resist­ r ec idues from previous years. This, a n ce to DDT, but not to diazinon, and coupled with the tendency of growers presumably not to other organophos­ to ~ i horten the sequence of crop ro­ phorus compounds . Be e tIe s from tation under conditions of concen­ Cache Creek were highly toler a nt to trated production, subjected this spe­ dieldrin, a nd the DDT - tolerance cies to increased selection pressure. shown in 1963 by beetles from Alex­ It has been shown (Varzandeh andria, Cache Creek, K a mloops, and et ai., 1954) that development of re­ Pavilion was reflected in the low mor­ sis tance h as no a pparent effect on tality counts of the composite sa mple the biotic potential of Musca domes­ after exposure to DDT in 1965. Lica L. Results of tuber damage as­ In the interior of British Columbia Oies3 m ents from field plots at Salmon the tuber h as developed River in 1965 clearly indicate that res istance to DDT and dieldrin in this applies as well to E . tuberis.

References Abbott, W. S. 1925. A method of computing the eff ectiveness of an insecticide. J. Econ. Entomol. 18:265-267. Banham, F. L. 1960. Soil insecticides for control of the tuber fl ea beetle, Epitrix tuberis Gent., in the interior of British Co lumbia. Can. J. Plant Sci. 40: 165-17l. Banham, F. L. 1961. The per sistence of certa in soil in secticides for control of the tuber flea beetle. Epitrix tuberis Gent., in the interior of British Columbia. Can. J. Plant Sci. 41:664-671. Brown, A. W. 1\. J 958. Insecticide resistance in . W.H.O. Monogr. Ser. 38. 240 p. Finlayson, D. G. , and C. L. Neil son. 1954. Experiments on the insecticidal control of the tuber flea beetie, Epitrix tuberis Ge nt., in the interior of British Columbia. Can. J . Agr. Sci. 34:156-160. Morrison, H. E . 1962. P er sonal communica ti on. As,oc. ProL Dept. of Entomology, Oregon St