BIOCHEMICAL ASPECTS OF INSECTICIDE RESISTANCE IN COTTON BOLLWORM FROM HANDAN OF HEBEI PROVINCE

摘要

The cotton bollworms, Helicoverpa armigera Hiibner, collected from Handan of Hebei Province, have evolved high resistance to pyrethroid, organophosphate and carbamate insecticides. The sensitivity of acetylcholinesterase (AChEs) to paraoxon and methomyl varied with the development stages of the cotton bollworm. After the treatments with LD5 and LD_(50) of parathion and methomyl to the cotton bollworms, the affinity of AChE to acetylthiocholine (ATCh) and acetyl-beta-methyl-thiocholine (MeTCh) increased significantly except the treatment of parathion using LD_(50) dosage while the sensitivity of AChEs to paraoxon significantly decreased. The sensitivity of AChEs to methomyl strongly increased in the treatment of parathion using LD_(50) dosages whilestrongly decreased in other treatments. The affinity of carboxylesterase to (3-naphthyl acetate (beta-NA) was higher in groups of treatment with insecticides than in group of control. The glutathione-s-transferase (GST) activity significantly decreased in the induced groups using LD5 dosages, while increased in the selection groups using LD_(50) dosages. The effects of parathion and methomyl on the phosphatases of cotton bollworm were related to the dosages of application and the time after treatment and the effect on the alkaline phosphatase was stronger than on acid phosphatase.