多杀菌素对舞毒蛾保护酶及几丁质酶的影响

Effects of spinosad on the activity of protective enzymes and chitinase in Lymantria dispar

为进一步揭示多杀菌素的杀虫活性及作用机理,采用生化方法测定了多杀菌素对舞毒蛾3龄和5龄幼虫体内几种保护酶活性的影响。结果表明:多杀菌素处理舞毒蛾3龄和5龄幼虫后,其体内的过氧化氢酶(CAT)活性无明显变化,而酚氧化酶(PO)的活性表现为先激活后抑制作用。多杀菌素对舞毒蛾3龄幼虫体内超氧化物歧化酶(SOD)、过氧化物酶(POD)同样表现为先激活后抑制作用,其中在处理3～6h时,对酶的激活作用达到最高(P<0.01);但对5龄幼虫体内这两种酶具有明显的激活作用,其中在处理3h时,对酶的激活作用最强,分别为同期对照的1.543和1.716倍,差异极显著(P<0.01),6h后无明显差异。多杀菌素对舞毒蛾幼虫体内几丁质酶也存在影响,其中对处理3～12h3龄幼虫体内该酶具有激活作用,处理12～24h对5龄幼虫体内该酶具有明显抑制作用。因此,多杀菌素能有效干扰舞毒蛾幼虫正常的生理代谢,从而起到毒杀作用。

In order to better understand the insecticidal activity and mode of action of spinosad,its effect on the activity of protective enzymes and chitinase of 3rd and 5th instar larvae of Lymantria dispar was assayed in this study.The results showed that spinosad had no effect on catalase（CAT） activity,but significantly changed phenoloxidase（PO） activity in an activation-inhibition fashion for both 3rd and 5th instar larvae.The same significant ＂activation-inhibition＂ effect was also found on the activity of superoxide dismutase（SOD） and peroxidase（POD） in the 3rd instar larvae（P0.01）,with the maximum enzyme activations occurred 3-6 hours after spinosad treatment.Whereas the POD and SOD activity in the 5th instar larvae was significantly increased within 3 hours after the treatment（P0.01;with treatment/CK ratios being 1.543 and 1.716,respectively）,and no significant treatment effects were detected after 3-6 hours.The chitinase activity in the 3rd instar larvae was significantly activated 3-12 hours after spinosad treatment,while it was strongly inhibited in the 5th instar larvae 12-24 hours after the treatment.In conclusion,spinosad shows a significant effect on the activity of most protective enzymes and chitinase,and can interrupt normal metabolism of L.dispar larvae,therefore,has a potential to be an effective pesticide against this serious defoliator pest.