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为阐明Bt杀虫蛋白对次要靶标害虫粘虫Mythimna separata(Walker)(鳞翅目:夜蛾科)的生理学影响,本研究分析比较了粘虫高龄幼虫在室内取食低剂量Cry1Ac杀虫蛋白6,12,24和36h后,其体内主要的解毒酶(酯酶和谷胱甘肽-S-转移酶)、保护酶(超氧化物歧化酶、过氧化氢酶和过氧化物酶)和中肠蛋白酶(总蛋白酶、强碱性类胰蛋白酶、弱碱性类胰蛋白酶和类胰凝乳蛋白酶)等活性的变化。结果表明,取食Cry1Ac杀虫蛋白后,粘虫幼虫体内相关酶活力呈现不同的变化趋势:(1)酯酶、谷胱甘肽-S-转移酶、过氧化物酶(POD)、类胰蛋白酶和类胰凝乳蛋白酶活力较对照显著降低(P<0.05);(2)超氧化物歧化酶(SOD)活力较对照显著升高(P<0.05);(3)过氧化氢酶(CAT)活力于6,12和24h显著低于对照(P<0.05),36h时显著高于对照(P<0.05)。结果提示Cry1Ac杀虫蛋白主要通过抑制粘虫幼虫中肠解毒酶和蛋白酶的活性,扰乱SOD,CAT和POD3种保护酶的动态平衡而干扰幼虫的正常生理代谢,从而起到毒杀粘虫的作用。
In order to elucidate the physiological effects of Bt insecticidal proteins on Mythimna separata (Lepidoptera: Noctuidae), a secondary target insect, the present study analyzed the effects of low-dose Cry1Ac insecticidal protein After 6, 12, 24 and 36h, the main detoxification enzymes (esterase and glutathione-S-transferase), protective enzymes (superoxide dismutase, catalase and peroxidase) and Midgut proteases (total protease, strongly basic tryptase, weakly basic tryptase and chymotrypsin) and other activities. The results showed that the relative enzyme activities of armyworm larvae showed different trends after feeding Cry1Ac insecticidal protein: (1) Esterase, glutathione-S-transferase, peroxidase (POD) (2) The activity of superoxide dismutase (SOD) was significantly higher than that of the control (P <0.05); (3) The activities of catalase (CAT) ) Vitality at 6, 12 and 24 hours were significantly lower than the control (P <0.05), 36h was significantly higher than the control (P <0.05). The results suggest that Cry1Ac insecticidal protein can inhibit the normal physiological metabolism of larvae mainly by inhibiting the activity of detoxification enzymes and proteases in the midgut of armyworm larvae and disturbing the dynamic balance of the protective enzymes SOD, CAT and POD .