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 ۱, ۶, ۱۲, ۲۴, and ۴۸ h of exposure of larvae to low doses of these insecticides.Results: The susceptibility of FAW larvae to chlorantraniliprole and emamectin benzoate increased after ۴۸ h, and the LD۵۰ was ۰.۱۸ and ۰.۲۳ μg/larvae, respectively.EST-α and -β activity changed significantly in FAW larvae over time after exposure to insecticides. After only ۱ h, EST-α, and -β activity after exposure of larvae to insecticides at LD۱۰ showed no significant difference compared to control. However, under LD۳۰ treatments, the activity of EST-α and -β decreased significantly. Significant reduction of EST-α and -β activity was observed in larvae after ۴۸ h exposure to chlorantraniliprole at LD۳۰ (۰.۵ and ۰.۱۵ nmol/min/mg protein, respectively) followed by emamectin benzoate (۱.۱۹ and ۰.۲۹ 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.

Keywords:

Alpha esterase , Beta esterase , Chlorantraniliprole , emamectin benzoate , Spodoptera frugiperda , Sublethal effects