斑蝥素对粘虫几种代谢酶及多酚氧化酶的影响

Effects of cantharidin on four metabolizing enzymes and PPO in Mythimna separata(Walker) (Lepidoptera:Noctuidae)

为进一步探讨斑蝥素的杀虫作用机理,本研究采用叶碟饲喂法处理粘虫Mythimna separata(Walker)5龄幼虫,测定了饲喂处理后6,12,24,36和48h试虫体内羧酸酯酶(CarE)、酸性磷酸酯酶(ACP)、碱性磷酸酯酶(ALP)、谷胱甘肽S-转移酶(GST)和细胞色素P450Ο-脱甲基酶及多酚氧化酶(PPO)的活性。结果表明:斑蝥素可显著激活羧酸酯酶,处理后48h酶比活力最大,为同期对照的1.68倍;酸性磷酸酯酶在处理后6和12h活性变化不明显,处理24h后逐渐被激活,且与对照差异显著(P<0.05);明显抑制碱性磷酸酯酶,且随着处理时间的延长,抑制作用增强;对Ο-脱甲基酶表现为先抑制后激活的趋势;谷胱甘肽S-转移酶表现出先激活后抑制的影响;离体活体条件下均可显著抑制PPO活性。可见,斑蝥素可明显影响昆虫的代谢酶系,且其对碱性磷酸酶和多酚氧化酶的抑制作用可能与其毒杀作用有关。

In order to reveal the insecticidal activity and mechanism of cantharidin,the effect of cantharidin on activities of carboxyl esterase （CarE）,phosphatases,glutathione S-transferase （GST）,O-demethylase of cytochrome P450 and PPO in larvae of Mythimna separata （Walker） were assayed. The results showed that CarE in the treated insects was distinctly activated and at 48 h after treatment their specific activity was 1.68 times that of the control. ACP activity showed no distinct change at 6 h and 12 h after treatment,but was activated at 24 h after treatment and significantly different from the control （P0.05）. The activity of alkaline phosphatase （ALP） was inhibited obviously,and the inhibition became more intensive as the exposure time prolonged. The activity of O-demethylase was first inhibited,and then activated. GST activity was first activated,and then inhibited. PPO activity was strongly inhibited by cantharidin both in vitro and in vivo. It is so inferred that catharidin can affect the metabolic enzymes distinctly,and the inhibition on ALP and PPO may be related to its toxic effect.