对久效磷抗性棉铃虫品系的选育及其乙酰胆碱酯酶的研究

Laboratory selection for monocrotophos resistant strain of Helicoverpa armigera(Hübner)and study on its acetylcholinesterase

用久效磷对采集于山东聊城抗性地区的棉铃虫Helicoverpaarmigera (H櫣ｂｎｅｒ)进行抗性品系选育。经过 10代的室内选育 ,抗性倍数达 2 11 88倍 ,为选育前的 6 6 7倍。同时发现筛选后对氰戊菊酯、氯氰菊酯和灭多威的抗性分别下降了8 13,7 44和 13 36倍 ,对甲基对硫磷和辛硫磷的抗性基本保持不变。这说明久效磷与其他 5种被试药剂之间没有明显的交互抗性。还对抗、感棉铃虫体内AChE进行了研究 ,对久效磷抑制粗酶液的实验表明 ,抗性品系棉铃虫体内AChE的I50 是敏感品系的 3 18倍。酶液纯化使抗、感品系AChE的I50 分别下降 6 6 9和 3 49倍 ,说明粗提液中存在AChE保护因子 ,且这种保护因子在抗性品系中更有效。但纯化后 ,抗、感品系的AChE敏感性之间仍存在 1 6 6倍的差异。此外 ,两品系AChE的动力学参数也存在显著差异。

Monocrotophos resistance was selected in laboratory with the field resistant cotton bollworm,Helicoverpa armigera(Hübner)collected from Liaocheng County,Shandong Province.After ten selections with monocrotophos during sixteen generations,the resistance increased 6 67 fold and was as high as 211 88 fold when compared with a susceptible strain collected from Xinjiang.But the resistance of the selected strain to fenvalerate,cypermethrin and methomyl decreased by 8 13 ,7 44 and 13 36 fold,respectively,during the selection.Methylparathion and phoxim resistance was basically unchanged as compared with that of F 0.These indicate no significant cross resistance between monocrotophos and the other 5 insecticides tested.Acetylcholinesterase(AChE)in resistant and susceptible H.armigera was also studied.The results showed that AChE in resistant strain was much less sensitive to monocrotophos.The I 50 value for resistant AChE was 3 18 fold higher than that for susceptible.Partial purification of AChE to remove esterase and some other proteins increased the sensitivity dramatically.The I 50 reduced by 6 69 fold and 3 49 fold for resistant and susceptible strain,respectively.This indicated that there might be some factors protecting AChE,and which was more powerful in resistant strain.Even so,there was still 1 66 fold difference in the I 50 value of purified AChEs from resistant and susceptible strains.Kinetic parameters of AChE also showed significant difference between these two strains.So,it is concluded that the decreased sensitivity of AChE together with some other factors contributes to monocrotophos resistance.