Efficacy and field longevity of insecticides used for codling moth Background

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1 Efficcy nd field longevity of insecticides used for codling moth Chuck Ingels, UC Coopertive Extension, Scrmento County Bob Vn Steenwyk, Division of Insect Biology, UC Berkeley Steve Welter, Division of Insect Biology, UC Berkeley Frnces Cve, Division of Insect Biology, UC Berkeley Bckground Control of codling moth in per orchrds will become substntilly more difficult for mny growers when Guthion is withdrwn from the mrket. Most other products tht re currently vilble, when used with pheromone mting disruption, re generlly effective where codling moth popultions re reltively low, but they lck the bility to successfully control lrge popultions. Products tht re currently registered in pers nd hve t lest prtil control of codling moth re the orgnophosphtes Guthion (zinphos-methyl) nd Imidn (phosmet), the synthetic pyrethroids Dnitol (fenpropthrin) nd Asn (esfenvlerte), the neonicotinoid Assil (cetmiprid), insect growth regultors (IGRs) Confirm (tebufenozide), Intrepid (methoxyfenozide), Dimilin (diflubenzuron), nd Esteem (pyriproxifen), the sodium inhibitor Avunt (indoxcrb), nd the orgniclly cceptble Entrust (spinosd), (ADD: Wrrior Lmbd cyhlothrin). Orgnic growers lso use insecticidl spry oil for in-seson control Ech of these insecticides hs drwbcks. Guthion, the grower stndrd for severl decdes, increse spider mite popultions, but they were effectively controlled by other pesticides. Guthion lso controls mny secondry pests, but long restricted entry intervls nd the impending loss of the product from the mrket mke its outlook blek. Imidn hs shown fr less efficcy ginst codling moth thn Guthion. The IGRs hve generlly been more effective t controlling lefrollers thn codling moth. Synthetic pyrethroids re reltively effective, but they kill mny beneficil insects nd codling moth hve propensity to develop resistnce to these mterils. Another key fctor is tht most mterils re substntilly more expensive thn Guthion. Resistnce biossys conducted in 2003 by S. Welter found increses in zinphosmethyl resistnce with levels up to 0.89 µg /µl per moth in one orchrd. Anecdotl reports from S. Afric hve suggested tht levels of c. 1.2 µg /µl per moth were correlted with field filure of the mteril, yet these reports hve not been confirmed. Two compounds tht were seen s some of the most promising replcements for Guthion re Assil nd Dnitol. Sttisticlly significnt, but low levels of resistnce to Assil were found in 2003 in 4 orchrds when compred to the most susceptible orchrd, which lso hd the lowest levels of zinphosmethyl resistnce. Resistnce rtios rnged from 1.7 to 4.8. A similr pttern ws observed for Dnitol resistnce with sttisticlly significnt resistnce detected in 4 orchrds in Resistnce rtios were vrible, but reltively low, t 1.9 to 8.1 in comprison to popultions collected in the orchrds with the lowest levels of zinphosmethyl resistnce. A key fctor relted to the timing of insecticide pplictions is the effective durtion of insecticide residue on the fruit. The effective residul ctivity will vry with resistnce levels nd specific wether conditions. The occurrence of significnt vrition between popultions in field bsed pheromone-ssisted biossys my correlte to vrition in performnce.

2 Objectives 1. To determine the reltive efficcy nd residul ctivity of severl currently vilble insecticides on codling lrvl survivl on field-treted fruit in lbortory biossys. 2. To compre reltive infesttion rtes over time under commercil per growing conditions. Methods nd Mterils The field portions of the trils were conducted in Brtlett orchrds ner Wlnut Grove nd Firfield. The insecticides tested nd the rtes used re listed below. (It should be noted tht Intrepid works in prt by ovicidl ctivity, but only lrve were used in the biossys.) No other insecticides were pplied to these trees during the growing seson. per cre Tretment Scrmento Firfield Gl./Acre 150 gp 200 gp Assil 70WP 3.4 oz 3.4 oz Dnitol 2.4EC 21.3 oz 21.3 oz Guthion 50WP 3.0 lbs 2.0 lbs Imidn 70W b 7.0 lbs 6.0 lbs Intrepid 2F 16.0 oz -- Success 2SC oz Untreted control Ltron B1956 ws dded t 0.125% by volume b Tretment ph ws djusted to < 6. Scrmento Tril In this orchrd (spcing 10 x 20 ), ech spry ws pplied to four consecutive replicte trees on My 18, My 25, June 1, June 8, nd June 15. A prtil row ws used for ech week s spry, nd ech row ws seprted by n unspryed row to prevent drift. Four untreted trees were selected t the end of one of the prtil rows. Therefore, 104 trees were used in the tril (5 products x 4 replicte trees x 5 weekly timings, plus 4 untreted control trees). The sprys were pplied using hnd-held orchrd spryer operting t 250 psi with finished spry volume of 150 gl./cre (1.45 gl/tree). On June 16, 25 fruit per tree were hrvested nd tken to the Welter lb for lrvl ssy #1 (see below). Thus, on the single pick dte, rnge of residue ges ws smpled. On June 29, nother 25 fruit per tree were hrvested nd tken to the lb for ssy #2. These fruit were kept in cold storge for 2 weeks, during which time femle moths were collected from the field for portion of the study. The chrt below shows the residue ge for the two sets of fruit.

3 Spry Residue Age (weeks) Dte Assy #1 Assy #2 & #3 18-My My Jun Jun Jun 0 2 Lrvl Biossy #1. In erly to mid June, numerous ttempts were mde to collect femle codling moths from collection sttions tht consisted of white sheet drped over blck light. Attempted collections took plce in severl per districts during the evening hours in the weeks before fruit for ssy #1 were hrvested. However, insufficient moths were found to provide lrve for the first ssy, so lrve from Guthion-susceptible moths rered in the lb were used in ssy #1. A totl of 2,500 spryed fruit nd 25 control fruit were set up for biossy #1 from June Two lrve were plced on ech fruit inside gel cp, which ws wxed onto ech fruit. Lrve were evluted 5 dys fter setup, nd mortlity ws declred only when both lrve were ded. Lrvl Biossy #2. Lrve were plced on fruit from July similr to ssy #1, except tht only 20 fruit per replicte were infested with lrve from the Guthion-susceptible lb colony. The residue ge ws defined by the pick dte (June 29), since ging in cold storge (2 weeks) is presumbly negligible compred to the UV exposure during field ging. Lrvl Biossy #3. Lrve were plced on fruit from July s in ssy #2, except tht only 5 fruit per replicte were infested with lrve from moths collected from Fether River pple orchrd. Lrve from this popultion were highly resistnt to Guthion, with smple nlysis showing µg /µl resistnce. There ws no set up of 3-week-old residues (8 June sprys) except Assil; thus, we set up 2-,4-,5-, nd 6-week-old residue smples for ll products but Assil ws ssyed every week Summry of biossys: Fruit per Guthion Replicte Susceptibility Biossy #1 25 Susceptible Biossy #2 20 Susceptible Biossy #3 5 Resistnt Firfield 5 Susceptible

4 Firfield Tril In the Firfield orchrd (spcing 25 x 25 ), folir sprys were pplied to individul trees with hnd-held orchrd spryer operting t 250 psi with finished spry volume of 200 gl/cre (2.87 gl/tree). Sprys were pplied once only, on 16 June (221 DD fter 2 nd biofix). Five fruit per replicte were infested with lbortory-rered neonte lrve t 0, 7, 14 nd 21 dys fter tretment. Ech fruit ws infested by plcing two lrve in ech of two geltin cpsules, which were secured to the pers by hot prffin wx. Mortlity ws determined for ech cpsule 1 dy fter infesttion. Field control of CM ws evluted in this orchrd t the sme time s commercil hrvest on 21 July by inspecting mximum of 250 fruit per tree for CM infesttion. In ddition, 25 noninfested fruit were flgged per replicte (100 fruit per tretment) on the ppliction dy. The flgged fruit were exmined t 7, 14, 21, 28 nd 35 dys fter tretment (DAT) for CM infesttion. Control of PP nymphs, motile TSSM dults, motile ERM dults nd SJS crwlers ws evluted by lef-brushing 10 exterior nd 10 interior leves collected from ech tree weekly from 12 July through 25 July. The 25 leves were bushed nd the pltes were counted under mgnifiction in the lbortory. Results Lrvl Biossy #1. Lb-susceptible lrve re lrve tht were rered in the lb nd therefore re not resistnt to Guthion becuse they re not subjected to sprys of Guthion or cross-resistnt insecticides. In the Scrmento ssy #1, lb-susceptible lrve subjected to fruit treted with Guthion 0, 7, nd 14 dys prior hd very high mortlity rte, nd mortlity begn to decline 21 dys fter tretment (DAT) (Tble 1). Mortlity on fruit treted with Imidn begn to decline bout 14 DAT, wheres morlity of Assil-treted fruit begn to decline 7 DAT. Mortlity on fruit treted with Dnitol ppered to decline 14 DAT, but inexplicbly incresed 21 nd 28 DAT. The mode of ction of Intrepid is ovicidl in prt, so its efficcy on lrve ws significntly lower thn other insecticides, but higher thn untreted fruit. Lrvl Biossy #2. More fruit from ech tretment were hrvested 2 weeks fter the lst spry nd were plced in cold storge for 2 dditionl weeks. The insecticide brekdown during this 2- week cold storge period ws probbly negligible, so this period ws disregrded; i.e., the lst spry (June 15) ws considered 14 DAT even though fruit were not subjected to lb-susceptible lrve until July At the first evlution (14 DAT), Guthion gin resulted in the gretest mortlity numericlly, but it ws not significntly different from Dnitol or Imidn (Tble 2). Nor were these products significntly different t 28 nd 35 DAT. At dy 42, lrve subjected to Imidn hd significntly greter mortlity thn those subjected to Dnitol or Guthion. Assil resulted in significntly less mortlity thn Guthion t the first evlution (14 DAT), but the differences were not significnt t ny lter dte. As in Assy #1, Dnitol mintined reltively similr level of mortlity throughout the experiment, nd t 42 DAT, it hd the highest mortlity, lthough not significntly higher thn Guthion.

5 Lrvl Biossy #3. Lrve from field-resistnt codling moths showed very low mortlity when subjected to Assil-treted fruit (Tble 3). After 21 DAT, no lrve died. Mortlity ws reltively low even when lrve were subjected to residues for 12 dys. Firfield Studies. In the Firfield tril, in which fruit were spryed once (June 16) nd hrvested nd subjected to lb-susceptible codling moth lrve weekly for one dy only, lrvl mortlity from Guthion, Imidn, nd Dnitol did not differ significntly through 14 DAT, but Imidn ws slightly more effective t 7, 14, nd 21 DAT (Tble 4). Assil nd Success performed reltively poorly throughout the tril, but these products performed significntly better thn the untreted control. The Abbott s conversion of these dt, which corrects for the untreted control dt, is shown in Tble 5. Dmge in the field ws evluted weekly, but there were few differences between tretments (Tble 6). By dy 35, fruit treted with Success ws infested to the sme degree s the untreted control. Fruit treted with Imidn nd Dnitol mintined reltively low infesttion levels. At commercil hrvest, fruit treted with Imidn ws significntly less infested thn most other tretments (Tble 7). Dnitol nd Guthion were nerly identicl in infesttion nd lso reltively low. Assil-treted fruit were significntly more infested, nd Success ws most infested of the spryed tretments, but less infested thn the untreted control. Evlutions of secondry pests in July showed tht the single use of Guthion nd Imidn, nd to lesser extent Success, led to substntil buildup of psyll (Tble 8). All products reduced Sn Jose scle, but Assil nd Guthion slightly incresed twospotted spider mites, nd Guthion nd Success incresed Europen red mites. Discussion As would be expected, mortlity of lb-rered lrve ws generlly fr higher fter 5 dys (Scrmento) thn fter only 1 dy (Firfield). After 5 dys of exposure, Guthion killed nerly ll lrve for t lest 2 weeks nd Imidn killed nerly ll lrve for t lest week. After 1 dy of exposure, Imidn nd Guthion resulted in substntil, but lower mortlity, even fter 28 DAT. Dnitol ws similr fter 1 dy of exposure, but slightly less thn Imidn nd Guthion. Assil killed fewer lrve, fter both 1 nd 5 dys of exposure. Interestingly, lrve tht were highly resistnt to Guthion lso exhibited strong resistnce to Assil. Mortlity on fruit treted identiclly with Assil killed fr more lb-susceptible lrve thn field-resistnt lrve. This cross-resistnce is problemtic, lthough lrve in Scrmento district orchrds re generlly less resistnt to Guthion thn those from the Fether River pple orchrd. Assil ws very effective on lb-susceptible lrve immeditely fter sprying, but only fter 5 dys of exposure. Intrepid nd Success performed less thn optimlly in these studies, lthough Intrepid lso hs ovicidl ctivity.

6 Tble 1. (Scrmento Assy #1) Men Percent Mortlity of lb-susceptible codling moth t 0, 7, 14, 21 nd 28 dys fter tretment (DAT) fter 5 dys of exposure of lrve to pers treted with vrious insecticides. Tretment Form/c Assil 70WP 3.4 oz 95.9 c 82.0 c 79.9 c 83.9 c 70.5 c 2. Dnitol 2.4EC 21.3 oz 92.0 c 89.0 cd 82.0 c 93.0 c 93.9 d 3. Guthion 50WP 3.0 lbs 98.0 c 99.0 d 99.0 d 85.0 c 84.8 d 4. Imidn 70W 6.0 lbs 97.0 c 97.9 d 91.0 cd 84.0 c 88.0 d 5. Intrepid 2F 16.0 oz 49.9 b 37.0 b 23.0 b 41.0 b 43.0 b 6. Untreted Mens followed by the sme letter within column re not significntly different (Fisher's protected LSD, P < 0.05). Tble 2. (Scrmento Assy #2) Men percent mortlity of lb-susceptible codling moth lrve t 14, 21, 28, 35, nd 42 dys fter tretment (DAT) fter 5 dys of exposure to pers treted with vrious insecticides (fruit plced in cold storge for 2 weeks). Tretment Form/c Assil 70WP 3.4 oz 64.6 c b 51.3 b 38.8 b 2. Dnitol 2.4EC 21.3 oz 77.9 cd b 71.3 c 53.8 c 3. Guthion 50WP 3.0 lbs 92.3 d b 63.3 bc 45.6 bc 4. Imidn 70W 6.0 lbs 82.5 d b 70.9 c 35.1 b 5. Intrepid 2F 16.0 oz 45.5 b b 37.5 b 6. Untreted Mens followed by the sme letter within column re not significntly different (Fisher's protected LSD, P < 0.05).

7 Tble 3. (Scrmento Assy #3) Men percent mortlity of field-resistnt vs. lb-susceptible codling moth lrve t 14, 21 28, 35, nd 42 dys fter tretment (DAT) of pers with treted Assil (fruit plced in cold storge for 2 weeks). Tretment Form/c After 5 Dys of Exposure to Field-Resistnt Lrve Assil 70WP 3.4 oz Untreted After 12 Dys of Exposure to Field-Resistnt Lrve Assil 70WP 3.4 oz Untreted After 5 Dys of Exposure to Lb-Susceptible Lrve (From Tble 2) Assil 70WP 3.4 oz Untreted Tble 4. (Firfield Assy) Men percent codling moth mortlity t 0, 7, 14, 21 nd 28 dys fter tretment (DAT) with 1 dy of exposure to pers treted in Firfield. Tretment Form/c Assil 70WP 3.4 oz 47.8 b 40.0 bc 34.2 b 39.5 c 51.3 cd 2. Dnitol 2.4EC 21.3 oz 90.9 d 78.4 d 82.1 c 44.4 c 68.4 de 3. Guthion 50WP 2.0 lbs 87.5 cd 81.6 d 91.9 c 78.9 d 86.8 e 4. Imidn 70W 6.0 lbs 82.6 cd 97.4 d 95.0 c 92.1 d 73.7 e 5. Success 2SC 5.7 oz 63.6 bc 20.5 b 31.6 b 10.0 b 6. Untreted Mens followed by the sme letter within column re not significntly different (Fisher's protected LSD, P < 0.05).

8 Tble 5. (Firfield Assy) Men percent corrected (Abbott s) codling moth mortlity t 0, 7, 14, 21 nd 28 dys fter tretment (DAT) with 1 dy of exposure to pers treted in Firfield. Tretment Form/c Assil 70WP 3.4 oz Dnitol 2.4EC 21.3 oz Guthion 50WP 2.0 lbs Imidn 70W 6.0 lbs Success 2SC 5.7 oz Untreted Tble 6. (Firfield Field Study) Men percent codling moth-infested fruit t 7, 14, 21, 28 nd 35 dys fter tretment (DAT) of fruit tht ws not infested t dy of ppliction in Firfield. Percent CM Infesttion t DAT Tretment Form/c Assil 70WP 3.4 oz b 18.4 b 25.9 b 2. Dnitol 2.4EC 21.3 oz Guthion 50WP 2.0 lbs b 21.6 b 26.2 b 4. Imidn 70W 6.0 lbs Success 2SC 5.7 oz b 29.4 b 50.1 cd 6. Untreted b 34.2 b 57.2 d Mens followed by the sme letter within column re not significntly different (Fisher's protected LSD, P < 0.05).

9 Tble 7. (Firfield Field Study) Men percent codling moth-infested fruit inspected t commercil hrvest in Firfield. Men Percent Infested Fruit Tretment Form/c t Commercil Hrvest 1. Assil 70WP 3.4 oz 52.4 c 2. Dnitol 2.4EC 21.3 oz 38.9 b 3. Guthion 50WP 2.0 lbs 36.4 b 4. Imidn 70W b 6.0 lbs Success 2SC 5.7 oz 69.1 e 6. Untreted 80.9 f Mens followed by the sme letter within column re not significntly different (Fisher's protected LSD, P < 0.05). Dt nlyzed using n rcsin trnsformtion. b ph ws djusted to < 6. Tble 8. (Firfield Field Study) Men totl per psyll nymphs, Sn Jose scles, twospotted spider mites nd Europen red mites per 20 leves in Firfield. Tretment Form/c PP SJS TSSM ERM 1. Assil 70WP 3.4 oz b 5.8 b Dnitol 2.4EC 21.3 oz b 3. Guthion 50WP 2.0 lbs 77.7 c 14.3 b 3.5 b 15.0 b 4. Imidn 70W 6.0 lbs 54.0 bc b 3.0 b 5. Success 2SC 5.7 oz 41.3 b 19.8 bc 0.5 b 11.3 b 6. Untreted c Mens followed by the sme letter within column re not significntly different (Fisher's protected LSD, P < 0.05). ph ws djusted to < 6.