甜菜夜蛾田间种群对甲氨基阿维菌素苯甲酸盐和高效氯氰菊酯的代谢抗性机制

甜菜夜蛾Spodoptera exigua(Hübner)云南晋宁、上海奉贤和江苏六合种群对甲氨基阿维菌素苯甲酸盐抗性为45～437倍,对高效氯氰菊酯抗性为211～555倍,对其它药剂抗性不明显。这3个田间种群3龄幼虫多功能氧化酶、谷胱甘肽S-转移酶和酯酶的活力分别为室内敏感种群的2.7～8.4倍、1.9～8.6倍和1.6～5.7倍。多功能氧化酶抑制剂PBO和酯酶抑制剂DEF对甲氨基阿维菌素苯甲酸盐的增效比为1.2～4.3和1.3～7.7;PBO和DEF对高效氯氰菊酯的增效比为1.8～58和3.6～245;谷胱甘肽S-转移酶抑制剂DEM对这2种药剂均无增效作用。上述结果表明,解毒代谢增强可能是甜菜夜蛾田间种群对甲氨基阿维菌素苯甲酸盐和高效氯氰菊酯的重要抗性机理,与酯酶和多功能氧化酶活性升高有关,与谷胱甘肽S-转移酶活性升高无关。本文的研究结果还表明,对于代谢抗性机理复杂的多抗性田间种群,根据不同解毒酶抑制剂对药剂的增效作用判断不同解毒代谢酶在抗性形成中的作用更加可靠。

Metabolic mechanisms of resistance to emamectin and cypermethrin in field populations of Spodoptera exigua

Three populations of Spodoptera exigua （YN-JN, SH-FX, and JS-LH） showed high levels of resistance to emamectin （45 to 437-fold） and cypermethrin （211 to 555-fold） compared to a susceptible SWH strain. Increased activity of detoxification enzymes such as monooxygenases （2.7 to 8.4-fold）, glutathione S-transferases （ 1.9 to 8.6-fold） and esterases （ 1.6 to 5.7-fold） were detected in these populations compared with the SWH strain. The synergistic ratios （SRs） of the oxidase inhibitor （PBO） and the esterase inhibitor （DEF） to emamectin were 1.2-4.3 and 1.3-7.7 respectively and the SRs of PBO and DEF to cypermethrin were 1.8-58 and 3.6-245 respectively. The glutathione S- transferase inhibitor （DEM） displayed no significant synergism with these two insecticides. These results indicate that enhanced detoxification by both esterases and oxidases are important resistance mechanisms to emamectin and eypermethrin in S. exigua, and that enhanced detoxification is associated with increased esterase and oxidase activity, but not increased glutathione S-transferase activity. Multiple-pesticide resistance in many insect populations makes synergistic bioassays a more reliable method of determining the contribution of metabolic detoxification to resistance to specific insecticides.