多杀菌素亚致死浓度对小菜蛾解毒酶系活力的影响

Effect of Sublethal Concentrations of Spinosad on the Activities of Detoxifying Enzymes in the Larvae of Diamondback Moth Plutella xylostell

采用多杀菌素亚致死浓度,以浸叶法分别处理小菜蛾Plutella xylostella(L.)敏感种群(SS)和亚致死选育种群[Sub-SS,即用亚致死浓度(LC25)连续处理5代后的种群]的3龄幼虫,分别测定饲喂处理6、12、24、48和72h后小菜蛾体内羧酸酯酶(CarE)、谷胱甘肽S-转移酶(GST)和多功能氧化酶(MFOs)的活性,分析了酶活性的变化动态。结果表明,SS种群小菜蛾CarE的活性在不同时间段波动较大,经多杀菌素处理后,开始时段比活力增加,随着处理时间的延长,比活力逐渐被抑制,Sub-SS种群的GarE活力高于SS种群;多杀菌素对GST具有明显的诱导作用,亚致死浓度处理后GSTs比活力呈上升趋势,且具有一定的时间效应;对细胞色素P450酶系的O-脱甲基酶活性具有明显的抑制作用,多杀菌素亚致死浓度连续处理5代后,该酶活性更低。

The third instar larvae of two Plutella xylostella （ L. ） strains, one was susceptible to spinosad （SS strain） and the other was obtained by selecting the SS strain with LC25 spinosad for more than five generations （Sub-SS strain）, were treated with LC25 or LCs0 concentrations of spinosad using cabbage leaf dip method and then determined the activities of the detoxifying enzymes. After treated for 6 h, 12 h, 24 h, 48 h and 72 h, activities of the carboxylesterase （ CarE）, the glutathione S-transferase （GST） and the mixed-function oxidases （MFOs） were investigated,respectively. The results showed that the activities of the three enzymes changed with time and different treatments. The specific activity of Care in SS strain fluctuated significantly both in the control and LC25 or LCso treated groups. At the beginning of spinosad treatment, the specific activity of GarE increased but was inhibited gradually with the increase of treatment time. In general,the CarE activities of different treatment in Sub-SS strain were higher than those in SS strain. The GST activities were induced significantly by sublethal concentrations of spinosad and had an obvious time effect. However, the activities of O-demethylation of MFOs were distinctly inhibited by sublethal concentrations of spinosad. The activities of MFOs in the Sub-SS were lower than those in the SS strain.