Effect of sublethal treatments of imidacloprid against Aromia bungii on its parasitoid, Sclerodermus guani.

Abstract

This study aimed to determine whether sublethal doses of imidacloprid affect physiological and biochemical responses in Aromia bungii larvae that influence parasitism and offspring development of its parasitoids Sclerodermus guani. We first determined appropriate sublethal doses of imidacloprid against A. bungii by bioassay, then quantified feeding and biomass of A. bungii larvae with an artificial diet treated with sublethal doses of imidacloprid, and the activity of detoxification and defense enzymes in treated larvae. Subsequently, we determined how larvae fed with sublethal doses of imidacloprid affected the performance of S. guani. Results showed that sublethal doses of imidacloprid significantly decreased the feeding and biomass of A. bungii larvae, induced activity of the detoxifying enzyme GST, and inhibited the activity of another detoxifying enzyme CarE; the activity of antioxidant enzymes CAT, SOD, and POD were also induced and the effect was dose-dependent; total mortality of A. bungii larvae and developmental duration of S. guani offspring were not significantly affected, but compared with the control, the reproductive mortality rate of A. bungii decreased by 64.84%, 83.52%, and 100%, respectively at 0.5 mg/kg, 1 mg/kg, and 5 mg/kg; the egg production of S. guani female decreased by 46.21%, 53.87%, and 69.08%, respectively, and the emergence rate decreased by 46.10%, 43.89%, and 100%, respectively; the sex ratio (female:male) of S. guani offspring was also decreased. Sublethal doses of imidacloprid had a significant impact on S. guani via induction of strong physiological and biochemical responses in the larval body of A. bungii.