薇甘菊对昆虫和病原菌生物活性的初步研究

Preliminary Studies on the Bioactivity of Crude Extract from Mikania micrantha on Insect and Plant Pathogen

研究了薇甘菊MikaniamicranthaH B K 的乙醇、丙酮提取物对菜青虫Pierisrapae和小菜蛾Plutellaxylostella幼虫的生物活性,结果表明,提取物对菜青虫和小菜蛾幼虫具有较强的毒杀和拒食作用。质量浓度为500mg·L-1的乙醇提取物对1～2龄的菜青虫的毒杀作用达到80%,LC50=293 4mg·L-1对2～3龄小菜蛾幼虫的毒杀作用达到70%以上,LC50=343 5mg·L-1。相同质量浓度的丙酮提取物对2种幼虫的毒杀作用略低于乙醇提取物。质量浓度为125mg·L-1的乙醇、丙酮提取物对2种幼虫均具有拒食作用,前者拒食率分别为97 4%和70 4%,后者提取物的拒食率分别为96 5%和98 3%。薇甘菊(干样 培养基)0 02g mL的甲醇、丙酮提取物对辣椒疫霉Phytophthoracapsili、玉米大斑病菌Exserohilumturcicum菌丝的抑制率均为100%。

Preliminary studies on the bioactivity of crude extracts from Mikania micrantha H.B.K. on larva of Pieris rapae & Plutella xylostella were conducted. The results showed that the inhibitory and antifeedant activity of crude extract from M. micrantha. against larvae of Pieris rapae and Plutella xylostella are remarkably effective. The toxicity of 500 mg·L^(-1) ethanol extract against 1～2 instar larva of Pieris rapae were 80%, LC_(50)=293.4 mg·L^(-1), while to 2～3 instar larva of Plutella xylostella were over 70%, LC_(50)=343.5 mg·L^(-1). The toxicity of ethanol extracts to these two kinds of larva are better than that of acetone extract. Antifeedant activity of 125 mg·L^(-1) of ethanol extracts are good to both larva and antifeedant ratio are 97.4% and 70.4% respectively. The antifeedant ratio of acetone extracts are 96.5% and 98.3% respectively. In 0.02 g/mL (dry substance of M. micrantha/culture medium) concentration, inhibitory effect of carbinol and ethanol extract to Phytophthora capsili & Exserohilum turcicum are 100%.