多杀菌素对不同发育阶段甜菜夜蛾的毒力及其体内超氧化物歧化酶、过氧化氢酶和过氧化物酶的影响

The Toxicity of Spinosad to Beet Armyworm and Its Effect on Endogenous Enzymes of Protective System

对甜菜夜蛾的毒力测定结果表明,多杀菌素能显著降低其初孵幼虫的存活率、成虫的产卵量和成虫寿命。经6.25μg/mL药液处理的卵,其初孵幼虫存活率仅为7.48%,而对照则为76.72%;取食12.50μg/L药液的成虫,其产卵量和成虫寿命仅为取食蜂蜜水的1/6和1/2.5。随虫龄的增加,甜菜夜蛾幼虫对多杀菌素的敏感性显著降低,3龄、4龄幼虫的敏感性仅为2龄幼虫的1/9和1/16,且增效剂氧化胡椒基丁醚(PBO)与磷酸三苯酯(TPP)表皮点滴处理不表现增效作用。多杀菌素对甜菜夜蛾卵的孵化率、蛹重以及蛹的羽化率没有明显影响。亚致死剂量处理3龄幼虫后,其体内超氧化物歧化酶、过氧化氢酶和过氧化物酶等主要保护酶系的活性在处理后0～24h与对照差异不明显,保护酶系与甜菜夜蛾对多杀菌素敏感性之间没有明显关系。

The toxicity of spinosad to beet armyworm at different developmental stages was determined. Spinosad could significantly reduce the adult fecundity, adult lifetime and survival rate of neonate larvae. The survival rate of the neonate larvae of eggs treated with 6.25 μg/mL spinosad was only 7.48%, relative to the control of 76.72%. The fecundity and lifetime of adults fed with 12.5 μg/L spinosad were decreased to 1/6 and 1/2.5 of the control fed with honey solution. With the larval development, the sensitivity to spinosad decreased significantly, the LC50 of the third and fourth instar larvae to spinosad increased more than 9 and 16 times than that of second instar larvae. PBO and TPP have no synergism for spinosad and this insecticide also did not affect the hatchability of treated eggs, pupal weight and eclosion rate of treated larvae. There was no significant difference in the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in vivo in the third instar larvae between the control and the treatment with sublethal dose of spinosad within 0～24 hours, it seems there was no obvious relationship between the sensitivity of beet armyworm to spinosad and the activities of endogenous enzymes of protective system.