Effect of pederin on activity of digestive and detoxifying enzymes of Ephestia kuehniella (Lep: Pyralidae) and Tribolium confusum (Col: Tenebrionidae)

During the last decade, plant and microbial-derived metabolites have received growing attention as potential tools for pest management in agriculture. Pederin (C۲۵H۴۵NO۹) is a vesicant toxin produced by Pseudomonas-like bacterial symbionts of rove beetles within the genus Paederus (Col: Staphylinidae). In this study, the toxicity of pederin to two stored product pests, Ephestia kuehniella Zeller (Lep: Pyralidae) and Tribolium confusum Jacquelin du Val (Col: Tenebrionidae) was evaluated using laboratory bioassays. Probit analysis estimated the median lethal concentrations of pederin as ۱۳۱۱.۹۶ and ۵۹۶.۳۶ppm for E. kuehniella fourth larval instar and T. confusum adults, respectively. We also measured the activity of two major digestive enzymes (amylases and proteases) as well as three major detoxifying enzymes (P۴۵۰s monooxygenases, glutathione S-transferases, and carboxyl esterases) in insects treated orally with pederin. Feeding on pederin resulted in significant decrease in the activity of amylolytic, proteolytic, and carboxyl esterase enzymes, but significant increase in the activity of P۴۵۰s and glutathione S-transferases. Results of this study may highlight pederin as a novel source of pesticides with unique mode of action for use in pest management programs.