Effects of spinetoram on detoxifying enzyme and acetylcholin esterase activity in Helicoverpa armigera (Hübner)
Author of the article:)XIE Bing-Tang** ZHANG Li-Li WANG Bing-Jie LIANG Ge-Mei***
Author's Workplace：State Key Laboratory for Biology of Plant Diseases and Insect Pests, Chinese Academy of Agriculture Sciences, Beijing 100193, China
Key Words：spinetoram, Helicoverpa armigera, susceptibility, detoxifying enzymes, acetylcholin esterase
Abstract： [Objectives] To investigate the efficacy of the novel pesticide spinetoram as a means of controlling the cotton bollworm Helicoverpa armigera (Hübner) and the mechanism through which this pesticide affects insect pests. [Methods] The baseline susceptibility of H. armigera collected from different regions were tested, and changes in their detoxifying enzyme and acetylcholin esterase activity measured, after exposure to different doses of spinetoram (LC15，LC40，LC60，LC80). The toxicity of spinetoram to H. armigera was tested by spraying the chemical on food, and enzyme activity was measured by measuring enzyme kinetics. [Results] Compared to abamectin, spinetoram had high toxicity to H. armigera, achieving higher mortality faster, and differences in susceptibility among populations were small. After treatment with spinetoram, carboxylesterase (CarE) and glutathione-S-transferase (GST) activity significantly reduced in a dose-dependent fashion. The inhibition ratios of these two kinds of enzyme in H. armigera after treatment with different doses of spinetoram were 52.14%-89.46% and 8.09%-49.81%, respectively. However, the activity of mixed-functional oxidase (MFO) following treatment with different doses of spinetoram first increased, reduced and increased again; maximum MFO activity was 147.75% higher than that of the control. Acetylcholin esterase (AchE) activity increased with the dosage of spinetoram to a maximum of 96.69% compared to the control. [Conclusion] Spinetoram is highly effective against H. armigera compared to abamectin and has good prospects for controlling this pest in the field. The activity of CarE and GST significantly reduced in H. armigera larvae after treatment with spinetoram, whereas, the activity of AchE and MFO increased.