解毒酯酶在小菜蛾幼虫抗药性中的作用

THE ROLE OF DETOXICATION ESTERASES IN INSECTICIDE RESISTANCE OF DIAMONDBACK MOTH PLUTELLA XYLOTELLA LARVAE

本文研究了解毒酯酶在小菜蛾Plutella xylostella 抗性中的作用。增效试验表明,在抗性(R)小菜蛾幼虫中,TBPT(酯酶抑制剂)对拟除虫菊酯杀虫剂溴氰菊酯和氯菊酯均无明显的增效作用,但对马拉硫磷增效59.6倍;TPP(羧酸酯酶抑制剂)对马拉硫磷增效32.5倍。离体研究表明,R和S幼虫的α-和β-NA酯酶活性和V_(max)都没有明显的差异。对氧磷对R和S幼虫酯酶的抑制作用都很强,而TBPT和TPP都很低。R幼虫的α-NA酯酶的K_m值是S的1.75倍,而β-NA酯酶的K_m无明显的品系差异。R和S幼虫的磷酸酯酶活性都很低,而且无品系差异。由此可见,小菜蛾对马拉硫磷的抗性也许与一般的非专一性酯酶活性关系不大,而与高度专一的马拉硫磷羧酸酶活性增高有关。

The role of detoxication esterases in the larvae of diamondback moth, Plutella xylotella. resistance to insecticides was examined through in vivo and in vitro experiments. Synergic ac-tion of deltamethrin, permethrin and malathion with the general esterase inhibitor TBPT and the carboxylesterase inhibitor TTP against larvae of resistant strain showed that TBPT and TPP had effective synergic activity for malarhion, but no synergism for pyrethroids. The sy-nergism factors of TBPT and TPP with malathion were found to be 59 and 32, respectively. The results of studies in vitro showed that: 1. There was no significant differences between the resistant and susceptible strains in esterase activity and Vmax 2. Inhibition by paraoxon was very strong both in the resistant and susceptible larvae, but very week by TBPT and TPP. The I50S determined with these three inhibitors were similar in the resistant and susceptible strains. 3. Km with alpha-NA in resistant larvae was 1.75 times higher than that in susceptible larvae, but there was no clear difference with beta-NA. The phosphatase activity was very low and the difference between the two strains is not significant. The results of studies in vitro and in vivo suggest that resistance of the diamondback moth to malathion may be only related to a highly specific malathion carboxylesterase and not related to general non-specific esterases.