Esterase Activity in Homogenates of Spodoptera Frugiperda (J.E. Smith) Exposed to Low-Lethal Doses of Chlorantraniliprole and Emamectin Benzoate

Background: Chlorantraniliprole and emamectin benzoate have been widely used to control pests including FAW. For effective pest control, the sublethal effects of these insecticides should be considered. Methods: The toxicity of chlorantraniliprole and emamectin benzoate to third-instar FAW larvae has been determined using topical application. Alpha esterase (EST-α) and beta esterase (EST-β) activity were also assessed after 1, 6, 12, 24, and 48 h of exposure of larvae to low doses of these insecticides. Results: The susceptibility of FAW larvae to chlorantraniliprole and emamectin benzoate increased after 48 h, and the LD50 was 0.18 and 0.23 μg/larvae, respectively.EST-α and -β activity changed significantly in FAW larvae over time after exposure to insecticides. After only 1 h, EST-α, and -β activity after exposure of larvae to insecticides at LD10 showed no significant difference compared to control. However, under LD30 treatments, the activity of EST-α and -β decreased significantly. Significant reduction of EST-α and -β activity was observed in larvae after 48 h exposure to chlorantraniliprole at LD30 (0.5 and 0.15 nmol/min/mg protein, respectively) followed by emamectin benzoate (1.19 and 0.29 nmol/min/mg protein, respectively) compared with control activity. Conclusion: Sublethal doses of chlorantraniliprole and emamectin benzoate affected activities of EST-α and -β of FAW.