关键词: 菜青虫, 苍耳, 环氧苍耳素Ⅰ, 中肠, 消化酶, 羧酸酯酶, 酶活性

Abstract: 【Aim】 This study aims to reveal the mechanism of epoxyxanthatin Ⅰ (sesquiterpe lactone from Xanthium sibiricum) on Pieris rapae larvae. 【Methods】 The activity of midgut protease, amylase and carboxylesterase in P. rapae larvae were investigated by feeding to 4th larvae of P. rapae. 【Results】 Epoxyxanthatin Ⅰ showed the most obvious inhibition on midgut protease, whose activities were inhibited 20.95%, 29.38% and 50.06% at 12 h, 24 h and 48 h after treatment respectively, while it showed the less obvious inhibition on midgut amylase, whose activities were inhibited 11.89%, 39.01% and 31.92%, respectively. Meanwhile, no significant differences in carboxylesterase activity were detected between the controls and the epoxyxanthatin Ⅰ treated samples at 12 h after treatment, while the activity was obviously inhibited at 24 h after treatment and significantly increased at 48 h after treatment compared with that of the control. 【Conclusion】 The results suggest that the inhibition effect of epoxyxanthatin Ⅰ on midgut digestive enzymes of insects may be one of the causes to inhibit feeding and growth of insects.

Key words: Pieris rapae, Xanthium sibiricum, epoxyxanthatin Ⅰ, midgut, digestive enzyme, carboxylesterase, enzyme activity