Biochemical Mechanisms of Azinphosmethyl Resistance in the Tufted Apple Bud Moth Platynota idaeusalis

Abstract

Potential mechanisms of resistance to azinphosmethyl, an organophosphate insecticide, were examined in five field populations of the tufted apple bud moth Platynota idaeusalis (Walker). Adult male moths from resistant and susceptible populations were collected on sex pheromone traps and analyzed for glutathione transferase, general carboxylesterase, and cytochrome P 450 monooxygenase activity. Kinetics and inhibition profiles for acetylcholinesterase were also compared among populations. Significant intra- and interpopulation variation was demonstrated in these detoxification enzyme systems, but no resistance correlation was found to carboxylesterases, cytochrome P 450 monooxygenases, or glutathione transferase using the substrate 1-chloro-2,4-dinitrobenzene or for acetylcholinesterase activity. However, elevated glutathione transferase activity toward the model substrate 1,2-dichloro-4-nitrobenzene was consistently associated with azinphosmethyl resistance.