Activity of eleven enzymes in nymphs of Lipaphis erysimi as affected by 2,4-D (herbicide) treatment

The activity of eleven enzymes involved in development, ageing and in metabolism of xenobiotics in insects, was investigated under the influence of 2,4-D (2,4-Dichlorophenoxyacetic acid), in the mustard aphid, Lipaphis erysimi (Kaltenbach) (Rhynchota Aphididae), after treating the 2 instar nymphs for 13, 25 and 37 h. Studies of two hydrolases and one group transfer enzyme revealed significant effects of 2,4-D on the activity of these enzymes. The activity of esterases and glutathione S-transferases increased and that of ATPase decreased with the treatment. Observations on the activity of eight oxidoreductases revealed a significant induction in superoxide dismutase and catalase activity and no effect on the activity of NADH dehydrogenase, NADH oxidase, glutathione reductase and glutathione peroxidase, and a significant reduction in the activity of O-demethylase and succinate dehydrogenase. It was concluded that the increase in activity of esterases, glutathione S-transferases, superoxide dismutase and catalase might be due to their involvement in the metabolism and degradation of 2,4-D.