Influence of Soybean Leaf Extracts on Ester Cleavage in Cabbage and Soybean Loopers (Lepidoptera: Noctuidae)

Abstract

Midgut-mediated ester cleavage of p-nitrophenyl acetate increased in Trichoplusia ni (Hübner) larvae that were fed on diets containing extracts from resistant and susceptible soybean, Glycine max (L.) Merr., varieties. Activity ranged as follows: control < susceptible < resistant variety. The opposite trend was noted for ester cleavage by midguts of Pseudoplusia includens (Walker) larvae fed on the same diets, such that activity ranged as follows: control > susceptible > resistant variety. The use of the inhibitors piperonyl butoxide and S,S,S-tri-n-butyl phosphorotrithioate indicated that ester cleavage was primarily mediated by hydrolytic esterases.