7-脱甲氧基娃儿藤碱对小菜蛾的胃毒活性及作用机理初探

Stomach Toxicity and Action Mechanism of 7-Demethoxytylophorine on Plutella xylostella L.

7-脱甲氧基娃儿藤碱是从杀虫植物牛心朴子中分离出的一种重要生物碱,具有多种生物活性。本文以小菜蛾为试虫,采用叶碟添加法研究了7-脱甲氧基娃儿藤碱对3龄小菜蛾幼虫的胃毒活性及对肠组织及消化酶活性的影响。结果表明:7-脱甲氧基娃儿藤碱对小菜蛾有较好的胃毒活性,浓度为8.00 mg/m L时,7 d死亡率为76.67%。死亡试虫的中肠上皮细胞被破坏;淀粉酶、蛋白酶和脂肪酶活性明显受到抑制,处理48 h后淀粉酶、蛋白酶和脂肪酶的抑制率分别为71.60%、93.38%、89.20%。实验结果说明:7-脱甲氧基娃儿藤碱对小菜蛾的胃毒作用可能与药液对中肠上皮组织的破坏和消化酶活性抑制有关。

7-Demethoxytylophorine is an alkaloid isolated from insecticidal plant Cynanchum komarovii. In this study, the stomach toxicity of 7-demethoxytylophorine on 3th instar larvae of Plutella xylostella L. was tested with a leaf dipping method. The possible mechanism of action was examined based on the analysis of the effects of 7-demethoxytylophofine on the digestive enzyme and midgut tissues of P. xylostella. The results indicated that 7-demetbexytylophorine had a sig- nificant toxicity on P. xylostella. At the concentration of 8.00 mg/mL, the mortality rate was 76.67%. Meanwhile,an obvious damage in the poisoned larva/＇ s midgut was observed. The activity of amylase, proteinase and lipase was signifi- cantly inhibited by 71.60% ,93.38% and 89.20% after 48 h of treatment. The results suggested that the stomach toxic- ity of 7-demethoxytylophofine against P. xylostella might be related to its damage on the midgut tissues and the inhibition in the digestive enzyme activity of P. xylosteUa larve.