Pisani-Borg_1996_Pestic.Biochem.Physiol_54_56

Using [14C]diazinon, it was found that four molecules accounted for most of the metabolites afterin vitroorin vivoincubation withDrosophila melanogaster.RalDDTR, an insecticide-resistant strain ofDrosophila,produced higher amounts of each metabolite than CantonS, a susceptible strain. However, the degradative metabolic pathway giving hydroxydiazinon and pyrimidine was twofold faster than the activating metabolic pathway giving hydroxydiazoxon and diazoxon. Clofibrate and phenobarbital increased the metabolism of diazinon in induced, susceptible flies. Phenobarbital was more potent than clofibrate in stimulating the hydroxylation of diazinon. Kinetic analysis ofin vivoinhibition of brain acetylcholinesterase by diazinon or hydroxydiazinon demonstrated that degradation of diazinon, especially in RalDDTR, was delayed compared to the degradation of hydroxydiazinon. Varying levels of diazinon tolerance amongDrosophilastrains may be explained by differential metabolic pathways. The most conclusive result was a strong interaction between tolerance and the rate of formation of hydroxylated derivatives.