Abstract
Lambda-cyhalothrin is a synthetic pyrethroid insecticide that is widely used to control leaf-eating pests. Because of increased insecticide resistance, an understanding of sublethal cross-generational effects of insecticides is important. We examine the effects of sublethal concentrations (SLCs) (LC(10), LC(20), and LC(40)) of lambda-cyhalothrin on the growth, reproduction, and detoxification enzyme activities of F(0) and F(1) generation Henosepilachna vigintioctomaculata. Lambda-cyhalothrin is toxic to adult H. vigintioctomaculata, with an LC(40) at 48 h of 0.355 mg L(-1). At SLCs, lambda-cyhalothrin significantly reduces the longevity and average fecundity of F(0) and F(1) adults, and prolongs the durations of the egg, larval, and pupal stages and adult preoviposition period. Additionally, an increased lambda-cyhalothrin concentration significantly decreases net reproductive rates, and both finite and intrinsic rates of increase in the F(1) generation, and significantly increases the average generation cycle. The detoxification enzyme activity of F(1) adults treated with SLCs of lambda-cyhalothrin for 48 h trends upwards. Results indicate that low concentrations of lambda-cyhalothrin induce glutathione S-transferase and carboxylesterase activities and inhibit multifunctional oxidase activity. The growth, development, and reproduction of the H. viltioctomaculata F(1) population remain inhibited by lambda-cyhalothrin treatment in the adult stage, and inhibitory effects increase with increased lambda-cyhalothrin concentration. The control efficacy of lambda-cyhalothrin against H. viltioctomaculata shows cross-generational effects.