The Colorado potato beetle (CPB), Leptinotarsa decemlineata Say, is the principal pest of potatoes in North America and Europe. To control this insect farmers depend primarily on the use of insecticides. However, whole classes of insecticides have failed to exhibited long-term success because of the resistance development. Since 1995, imidacloprid (AdmireŽ, ProvadoŽ), a neonicotinoid compound, has been vital for the control of the Colorado potato beetle in many areas of the United States. We have detected high levels of resistance to this compound in Colorado potato beetle populations collected in Long Island, NY in less than three years of use. Since imidacloprid is a relatively new insecticide, little has yet been published about its metabolism or the mechanism of resistance. We have studied the differences between an imidacloprid CPB resistant strains and a standard susceptible strain in the uptake, metabolism and elimination of imidacloprid and its metabolites. 14C-labeled imidacloprid was applied topically to adults at a dose that caused marginal initial knockdown and mortality in the susceptible strain. At intervals from 0.5 hours to 10 days after dosage, total radioactivity in the excreta and the body were assessed. The relative amounts of parent compound and metabolites were determined in these fractions by thin-layer chromatography. The compound was rapidly absorbed and excreted by both the resistant and susceptible forms. Metabolic conversion before excretion was relatively minor. Further studies on the mechanism of resistance are being conducted.
Species 1: Coleoptera Chrysomelidae Leptinotarsa decemlineata (Colorado potato beetle)
Keywords: resistance, excretion
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