Effects of Fenvalerate, Phoxim and Their Mixture on Metabolic Enzymes in Helicoverpa armigera Hübner

Synergism of the mixture of fenvalerate and phoxim on the 3rd instar larvae of R strain of Helicoverpa armigera Hubner was assayed by topical application and the synergism was obvious. In vivo effect on metabolic enzymes in H.armigera was studied by sublethal dose of fenvalerate, phoxim and their mixture 24 h after treatment. The results showed that: ① The activities of mixed function oxidase in O-demethylation and aldrin epoxidation were easily induced in S strain, especially for the latter, but they were inhibited in R strain. ② All treatments showed inhibition to the activities of esterases to some degree, and the inhibition by phoxim was the strongest. The inhibition of carboxylesterase was stronger than that of non-specific seterase and more obvious in R strain than in S strain. ③ Effect on the activities of glutathione S-transferases coincided with the quantity of glutathione (GSH). Three insecticides showed inhibition to the activities of GST in S strain, most obvious for the mixture; but in R strain, only fenvalerate showed inhibition, phoxim and mixture showed induction.