Abstract: nduction of glutathione S-transferases (GSTs) by insecticides and plant allelo chemicals, and metabolism of insecticides by GSTs were investigated during 1992-1995 in cotton bollworms, Helicoverpa armigera (Htibner). GSTs of the midguts from cotton bollworms metabolized parathion-methyl and methomyl more quickly than diethylmaleate, o, odiethyl-phenyl phosphorothioate (SV₁) and mixtures of parathion-methyl and methomyl.At 24 h or 48 h after treatment with LD₅₀ of parathion or methomyl, the GSTs activity of cotton bollworms did not increase. Selection of LD₅₀ of parathion made GSTs activity increase 15% while selection of LD₅₀ of methomyl had no effect on GSTs activity. Midgut GSTs activity in cotton bollworm larvae was induced up to 18-fold by feeding on the artificial diet containing 0.01% of quercitrin compared with activity in larvae only fed with artificial diet and up to 4-fold compared with activity in larvae fed with the diet containing 2tridecanone or rutin. Toxicity of parathion-methyl to larvae of cotton bollworms reduced about 50% due to feeding on the diet with quercitrin. But the 0.01% of rutin, quercitrin and 2-tridecanone in diet had no effects on toxicities of methomyl and deltamethrin to larvae of cotton bollworms.

Key words: Helicoverpa armigera (Hiibner), insecticide susceptibility, allelochemical, glu- tathione S-transferase