Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2007
Publication Date: 3/10/2008
Citation: Yee, W.L. 2008. Effects of Several Newer Insecticides and Kaolin on Oviposition and Adult Mortality in Western Cherry Fruit Fly (Diptera: Tephritidae). Journal of Entomological Science. 43(2):177-190. Interpretive Summary: Cherry fruit fly is a serious quarantine pest of cherry in central Washington. Knowledge about the effects of newer and safer insecticides is needed to control the fly. Personnel at the Yakima Agricultural Research Laboratory in Wapato, WA, are determining the effects of newer insecticides and kaolin clay (a non-insecticide) on reducing or preventing egg laying by this fly into cherries. When sprayed onto cherries, all insecticides (azinphos-methyl, spinosad bait, imidacloprid, thiamethoxam, and indoxacarb) reduced the numbers of eggs flies laid into the cherries. Some insecticides did not need to be highly toxic or cause high mortality to reduce the numbers of eggs laid. When kaolin clay was sprayed on cherries, the numbers of eggs laid were also reduced. The results of this study are important because they show that eggs laid by cherry fruit flies can be reduced to similar levels by materials with different toxicities, the insecticides tested can reduce damage to cherries, and that in residential trees where no insecticides is desirable, kaolin may be useful in reducing egg laying and buildup of fly populations.
Technical Abstract: Effects of newer insecticides and kaolin-based particle film (Surround™ WP Crop Protectant), on oviposition and mortality in the western cherry fruit fly, Rhagoletis indifferens Curran, were determined. In a no-choice experiment, azinphos-methyl sprayed on cherries reduced oviposition by 98.5% compared with the control, whereas spinosad bait, imidacloprid, and thiamethoxam reduced it by 74.4% to 91.8% and indoxacarb reduced it by 61.7%. Despite reducing oviposition to similar levels, imidacloprid did not cause as much mortality as spinosad bait, spinosad, and thiamethoxam. Imidacloprid reduced oviposition more than indoxacarb, even though the two caused similar mortality. In a choice experiment, there were no differences in oviposition in untreated and insecticide-treated cherries, except fewer eggs were laid in spinosad-bait treated than untreated cherries. In a no-choice experiment using kaolin, flies laid up to 36 times more eggs in control than treated cherries. In a choice experiment, flies laid 10 times more eggs in untreated than kaolin-treated cherries. Results show oviposition by R. indifferens can be reduced to similar levels by materials with significantly different toxicities, and that none except spinosad bait is an oviposition deterrent. The high levels of oviposition reduction indicate these insecticides (except indoxacarb) can protect fruit from mature flies, but more work is needed to modify or improve them so that they can reduce oviposition as much as azinphos-methyl. In residential trees where none of these insecticides is desirable, kaolin may be useful in reducing oviposition and buildup of R. indifferens populations.