Biochemical Studies in Larvae of Agrotis ipsilon (Hüfnagel) Affected by Recent Insecticides

As field populations of black cutworms grow more resistant to conventional insecticides, the need for new and effective chemical means to control this insect is more important than ever. In this study, we examined the biochemical mechanisms underlying the toxicity of the sublethal effect of the new insecticides (emamectin benzoate, indoxicarb, chloranitraniliprole, and pyridalyl) against two strains of Agrotis ipsilon comprising the laboratory-susceptible (L-S) and the field-resistant (BK-R). Activity measurements of the main detoxification enzymes showed that new insecticides inhibited the activities of both glutamic oxaloacetic transaminase (GOT) and glutamine pyruvic transaminase (GPT), whereas the significant activity of glutathione S-transferase (GST) was observed, suggesting that the inhibition of detoxification contributes to the enhancement toxicity against A. ipsilon larvae. A significant decrease in the effect of sublethal dose was also observed between the control larvae in the content of protein, lipid, and glycogen, and treated larvae in two strains. According to these results, the treated larvae were negatively affected in both two tested strains compared with untreated larvae in control.

Keywords:

enzyme activity , Energy reserves changes , Newer insecticides