甲氨基阿维菌素苯甲酸盐亚致死剂量对不同敏感性棉铃虫解毒酶活性的影响

室内用甲维盐对棉铃虫选育20代，获得敏感性降低2.32倍的汰选种群(RP20)。分别采用甲维盐对同源对照种群(CP)和RP20的亚致死浓度LC25对应处理两种群的3龄初幼虫48 h，测定试虫在3~6龄不同龄期内羧酸酯酶(CarE)和谷胱甘肽S 转移酶(GST)活性，分析酶活性变化动态。结果表明，(1)两种群(CP和RP20)均随龄期的增长，CarE比活力显著增大，而GST比活力先降低后趋于稳定。(2)CK处理下，RP20与CP相比，CarE比活力在3~6龄均增大且4~6龄差异显著，而GST比活力变化较小，仅3龄和6龄显著增大。(3)与CK处理相比，甲维盐LC25处理，两种群各龄期CarE比活力均增大，且CP试虫在4龄、6龄GST比活力显著增大，在3龄、5龄无显著差异，而RP20的3龄幼虫体内GST比活力被显著抑制，在4~6龄GST比活力无明显变化。初步判断，棉铃虫对甲维盐敏感性降低与CarE比活力增大有关；甲维盐亚致死剂量对棉铃虫CarE活性具有一定的诱导作用。

Effects of sublethal dose of emamectin benzoate on activities of detoxifying enzymes in Helicoverpa armigera of different sensitivities

After 20 times of resistance selection with emamectin benzoate, the resistance selected population (RP20) developed 2.32 fold lower sensitivity to the insecticide compared with the homologous control population (CP). The 3rd instar larvae of the two populations were treated with the LC25 dose of emamectin benzoate for 48 h, and then activities of carboxylesterase (CarE) and glutathione S transferase (GST) at 3rd, 4th, 5th and 6th instars were determined. The results were as follows: (1) With age increasing, activities of CarE increased significantly, and GST tended to be stable with low initial activity in both CP and RP20. (2) Compared with the CP under control treatment (CK), activities of CarE of RP20 increased in the 3rd-6th instars and significantly changed in the 4th-6th instars. However, GST activities of RP20 were not markedly changed, but significantly increased at 3rd and 6th instars. (3) Compared with CK treatment, activities of CarE in both populations increased after LC25 treatment. GST activities of CP significantly increased at 4th and 6th instars but was not markedly changed at 3rd and 5th instars. However, GST activities of RP20 decreased significantly at 3rd instar, but was not markedly changed in the 4th-6th instars.The preliminary investigations suggested that the decrease of the sensitivity of H. armigera to emamectin benzoate may be related with CarE activity, and CarE activity was induced by the sublethal dose of emamectin benzoate.