环氧虫啶对苜蓿蚜的毒力及对其体内解毒酶活性的影响

为研究桥环新烟碱类化合物对苜蓿蚜的影响，以吡虫啉为对照药剂，采用带虫浸叶法测定了环氧虫啶等桥环新烟碱类化合物对苜蓿蚜的毒力及对其体内解毒酶活性的影响。结果表明:以环氧虫啶为代表的七元桥环新烟碱类化合物对苜蓿蚜具有较好的杀虫活性，其中，环氧虫啶的LC50值为3.454 mg/L，高于八元桥环新烟碱化合物。酶抑制剂顺丁烯二乙酯（DEM）和胡椒基丁醚（PBO）对环氧虫啶均具有显著的增效作用，增效比分别为4.02和3.22；而对照药剂吡虫啉仅PBO对其具有明显增效作用。与空白对照组相比，经LC50浓度环氧虫啶和吡虫啉处理后，存活苜蓿蚜体内谷胱甘肽S-转移酶（GSTs）和细胞色素P450s活力均显著升高（P<0.05），其中，环氧虫啶处理组GSTs和P450s活力分别达到（2.730±0.012）和（0.239±0.009）μmol/（mg pro.·min），诱导能力弱于吡虫啉；而苜蓿蚜体内羧酸酯酶（CarE）活性则无明显变化。研究显示，在苜蓿蚜对环氧虫啶的解毒代谢过程中，GSTs和细胞色素P450s可能发挥着主要作用。

Toxicity of cycloxaprid to Aphis craccivora (Koch) and its effects on detoxification enzymes

To investigate the effects of bridged-neonicotinoid compounds onAphis craccivora (Koch), the toxicity of cycloxaprid and the other three bridged-neonicotinoid compounds onA. craccivora and its effects on detoxification enzymes were determined by leaf dipping method using imidacloprid as the control. The results showed that cycloxaprid and other seven-membered bridged neonicotinoid compounds displayed high insecticidal activities againstA. craccivora. The LC50 of cycloxaprid was 3.454 mg/L, which is higher than that of the eight-membered bridged neonicotinoid compounds. The synergistic ratios of enzyme inhibitors DEM and PBO were 4.02 and 3.22, respectively. Both compounds showed remarkable synergistic effects on the toxicity of cycloxaprid, whereas only PBO could significantly enhance the toxicity of imidacloprid. Further enzyme activity tests revealed that the activities of detoxification enzymes, namely, glutathioneS-transferase (GSTs) and cytochrome P450 enzymes (7-ethoxycoumarin-O-deethylase) inA. craccivora, could be enhanced significantly (P< 0.05) by the treatment of cycloxaprid and imidacloprid (LC50 level). Although cycloxaprid could enhance the activities of the above two enzymes to (2.730 ± 0.012) and (0.239 ± 0.009) μmol/(mg pro.·min), respectively, it is still lower than that of imidacloprid. No significant change was observed for the activities of carboxylesterase (CarE). The above results indicated that GSTs and P450s might play key roles during the detoxification of cyclcxaprid inA. craccivora.