甲氧虫酰肼对棉铃虫解毒酶活力的亚致死效应研究

Sublethal effects of methoxyfenozide on the activities of detoxification enzymes in Helicoverpa armigera

采用亚致死剂量(LC40浓度)的甲氧虫酰肼处理棉铃虫抗甲氧虫酰肼种群(R)和同源敏感种群(S)3龄初幼虫48 h,测定了3～6龄期幼虫体内多功能氧化酶(MFO)、酯酶(EST)和谷胱甘肽S-转移酶(GSTs)的比活力变化。结果发现:经亚致死剂量甲氧虫酰肼处理后,S种群EST比活力除4龄幼虫外均有所升高,且仅在3龄期升高明显;GSTs比活力在5龄幼虫体内显著升高,其他龄期无明显变化;MFO比活力在6龄幼虫体内表现为降低,其他龄期无显著变化。对于R种群,3龄和6龄幼虫体内EST比活力显著降低,各龄期的GSTs和MFO比活力均显著降低。空白对照R种群3～6龄期幼虫的GSTs比活力均高于S种群;EST比活力仅3龄幼虫显著高于S种群;MFO的比活力仅5龄幼虫显著高于S种群。研究表明:棉铃虫对甲氧虫酰肼的抗性与GSTs比活力增大关系较为密切;LC40浓度的甲氧虫酰肼可诱导敏感种群EST和GSTs活力升高,而使抗性种群3种酶的活力受到抑制。

The 3rd instar larvae of methoxyfenozide-resistant （R） and homologous susceptible （ S ） populations of Helicoverpa armigera were treated with sublethal concentration （LC40） of methoxyfenozide for 48 h, and then the specific activities of mixed function oxidases （ MFO）, general esterases（EST） and glutathione S-transferase （GSTs） in 3rd, 4th, 5th and 6th instar larvae were measured. The results showed that,for S population,the activities of EST increased in 3rd,5th and 6th instars, especially in the 3rd instars, the activities of GSTs significantly increased only in the 5th instars, while the activity of MFO decreased in the 6th instars. For R populations, the activities of EST obviously decreased in the 3rd and 6th instars, and both activities of GST and MFO decreased significantly in all tested instars. Comparing with S population, the activities of GSTs of R population increased in 3rd-6th instars,but the activities of EST and MFO significantly increased only in the 3rd and 5th instars, respectively. The results suggested that the resistance of H. armigera to methoxyfenozide was closely related with increasing activities of GSTs; the activities of EST and GSTs in S population could be induced by LC40 of methoxyfenozide; but the three enzymes＇ activities were inhibited in R population at the same concentration.