苍耳不同分离物对害虫的拒食和忌避活性

为跟踪分离苍耳的活性成分,对苍耳叶和果实的甲醇提取物进行了液-液萃取分离,测试各萃取分离物对小菜蛾(Plutella xylostella)、菜青虫(Pieris rapae)和桃蚜(Myzus persicae)的拒食、忌避(或产卵忌避)活性以及对其化蛹和羽化的影响。结果显示,苍耳的乙酸乙酯分离物较之于甲醇水分离物具有更高的活性。在0.05 g/mL处理浓度下,苍耳叶乙酸乙酯分离物对菜青虫和小菜蛾幼虫选择性拒食率高达100%和44.13%,对菜青虫非选择性拒食率为94%,对小菜蛾的选择性产卵忌避率都在50%以上,对桃蚜的选择性忌避率高于70%;同时,苍耳果实乙酸乙酯分离物处理叶片后,菜青虫幼虫无一化蛹,小菜蛾高龄幼虫发育为成虫的比率仅为对照的13.80%。以上结果提示,苍耳的有效活性成分主要存在于乙酸乙酯分离相中,对菜青虫的作用效果好于小菜蛾。

Antifeedant and deterrent activity of different extracts from Xanthium sibiricum Patrin against insect pests

The methanol extracts of the fruit and leaves of Siberian cocklebur(Xanthium sibiricum Patrin) were extracted with ethyl acetate and water by liquid-liquid extraction in the laboratory for their antifeedant effect,oviposition-deterrent effect and pupation-inhibiting effect against three insect pests on crucifers,including the diamondback moth(Plutella xylostella),cabbage white butterfly(Pieris rapae) and peach aphid(Myzus persicae).Their antifeedant effects were examined using the larvae of P.xylostella and P.rapae by leaf disc choice bioassays,while their oviposition-deterrent effects were examined using the adults of P.xylostella by fresh leaf disc choice bioassays,and their inhabiting-deterrent effects on M.persicae were tested by using half-leaf choice bioassays.The results showed that the ethyl acetate extracts of X.sibiricum had higher antifeedant and deterrent activities than the methanol-water extracts,in particular the extracts from its leaves.The choice antifeedant rate of the ethyl acetate extracts from the leaf extracts against the larvae of P.rapae and P.xylostella were 100% and 44.13%,respectively,and the non-choice antifeedant rate against the larvae of P.rapae was 94%.Its choice oviposition-deterrent rate against P.xylostella was above 50%,and its choice inhabiting-deterrent rate against M.persicae was above 70%.Meanwhile,the ethyl acetate extracts from fruit extracts of X.sibiricum showed the highest inhibitory effect on larval development to pupae and emergence.No larvae of P.rapae pupated after treatment,but P.xylostella had a 13.80% pupation rate,compared with the control.It is suggested that the active components of X.sibiricum existed mainly in the ethyl acetate extracts,with antifeedant,oviposition-and inhabiting-deterrent effects,but P.rapae was more susceptible to them than P.xylostella.