亚洲小车蝗痘病毒与化学杀虫剂混用的杀虫效果及对寄主主要解毒酶活性的影响

Insecticidal effects of Oedaleus asiaticus entomopoxvirus in combination with chemical insecticides and effects on the main activities of detoxification enzymes of its host

亚洲小车蝗痘病毒(Oedaleus asiaticus entomopoxvirus,OaEPV)作为一种增效剂,分别与马拉硫磷、毒死蜱、高效氯氰菊酯、氟氯氰菊酯、溴氰菊酯化学杀虫剂混合饲喂亚洲小车蝗若虫,统计致死中浓度LC50和其混合使用后的增效比;测定虫体内与抗性有关的两种重要酶---羧酸酯酶(CarE)和谷胱甘肽S-转移酶(GSTs)的比活力。结果表明:OaEPV与化学杀虫剂混合饲喂亚洲小车蝗,OaEPV与毒死蜱、高效氯氰菊酯、氟氯氰菊酯、溴氰菊酯混用对亚洲小车蝗无明显的增效作用,OaEPV与马拉硫磷混用,具有一定的增效作用,增效比为1.42倍。混剂感染亚洲小车蝗,除与溴氰菊酯混用外,虫体的中肠部位CarE的比活力都受到了明显的抑制作用,其中OaEPV与马拉硫磷混用下降了4.21倍,抑制作用最大。当OaEPV与氟氯氰菊酯、溴氰菊酯化学杀虫剂混用后,中肠部位GSTs受到了明显的抑制作用,而其脂肪体部位CarE和GSTs的变化无一定的规律性。结果提示痘病毒与农药混合处理时,病毒主要通过抑制中肠部位CarE比活力而增加了农药的杀虫效果。

Third-instar nymphs of Oedaleus asiaticus were fed on artificial diet mixed with combinations of O. ctsiaticus entomopoxvirus （OaEPV） and the insecticides of malathion, chlorpyrifos, β-cypermethrin, cyfluthrin and dehamethrin, in which OaEPV was used as a synergist. Mortalities were observed, and LC50 values and the synergic ratios were determined. The specific activities of two enzymes （carboxylesterase, CarE; glutathione S-transferases, GSTs） in relation to the pest resistance to insecticides were also assayed. The results showed that combinations of OaEPV and chlorpyrifos, β-cypermethrin, cyfluthrin, deltamethrin had no distinct synergism, whereas the combination of OaEPV and malathion was more effective than malathion alone in some degree. The synergic ratio of OaEPV to malathion was 1.42 times. Except dehamethrin, the specific activities of CarE in the midgut of O. ctsiaticus nymphs treated with mixtures of OaEPV and other insecticides mentioned above were inhibited obviously as compared to insecticide treatments alone. The highest inhibition ratio of CarE specific activity, 4.21 times, appeared when OaEPV was mixed with malathion. The specific activities of GSTs in the midgut of O. asiaticus treated with the mixtures of OaEPV and cyfluthrin or OaEPV and deltamethrin were evidently inhibited as compared to insecticide treatments alone. The specific activities of CarE and GSTs in the fat body of 0. asiaticus treated with the mixtures, however, were not significantly changed as compared to insecticide treatments alone. The results suggest that OaEPV enhances the insecticidal effects of chemical insecticides against O. asiaticus by inhibiting the specific activity of CarE in the midgut.