田间菜蛾绒茧蜂对有机磷敏感性监测及毒理机制分析

对甲胺磷敏感性的田间监测结果显示,绒茧蜂存在着抗性演化,毒力生物测定结果与AChE的K_i值的监测结果呈明显的相关性,每年9月至次年2月期间AChE敏感性最低,8月期间敏感性最高。甲胺磷可显著地抑制绒茧蜂AChE、CarE和GSTs的活性。PB和TPP对AChE的活体抑制率极低,但PB可强烈抑制CarE的活性,而TPP仅在高浓度时对CarE有较显著的抑制作用,PB对甲胺磷有显著的增效作用,而TPP对甲胺磷无增效作用。AChE的K_m、V_(max)及K_i值研究结果表明,田间绒茧蜂对有机磷和氨基甲酸酯的抗性与AChE对杀虫剂的不敏感性有关。由此认为,绒茧蜂对有机磷的抗性主要与其最重要的靶标酶AChE的敏感性改变及多功能氧化酶有关。

Monitoring of susceptibility to organophosphates and analysis of toxicological mechanism in A. plutellae Kurd.

Field monitoring of A. plutellae Kurd, susceptibility to methamidophos showed that there was a resistance evolution under the insecticide selection pressure. The bimolecular rate constant Ki of acetylcholinesterase ( AChE) was significantly correlated with the contact toxicity. Throughout the year , the AChE sensitivity was the highest in August and then fell to the lowest from September to next February. The AChE sensitivity varied with the insecticide selection pressure in the environment. The activities of AChE, carboxylesterase (CarE) and glutathion S-transferase (GSTs) could be strongly inhibited by methamidophos, in vivo . Piperonyl butoxide(PB) and triph-enyl phosphate (TPP) showed very weak inhibition on the activity of AChE, in vivo, PB strongly inhibited CarE activity,while TPP exhibited significant inhibition on CarE activity only when its concentration was high. Therefore,PB had significant synergic effects to methamidophos, but TPP did not. According to the estimates of the kinetic parameters Km,Vmax and Ki of AChE, the resistances of A. plutellae Kurd. to organophosphates (OPs) and carbametes were related to the insensitivity of AChE to the insecticides. It could thus be concluded that the resistance of A. plutellae Kurd, to OPs was mainly attributed to the change of AChE sensitivity and also to the microsomal mixed-function oxidase.