万寿菊对斜纹夜蛾的生物活性测定

The Bio-activity of Tagetes erecta on Spodoptera litura

采用室内浸虫法测定万寿菊不同部位浸提液对斜纹夜蛾3龄幼虫的生物活性,筛选出具有较强杀虫效果的活性部位。以质量浓度梯度为625,1 250,2 500,5 000,10 000 mg/L的万寿菊花、茎、叶、根乙醇提取物及根的石油醚萃取物、氯仿萃取物、乙酸乙酯萃取物及不溶物分别处理斜纹夜蛾3龄幼虫,12,24,48 h后观察死亡虫体数,计算死亡率和校正死亡率。结果显示,万寿菊根、茎、叶、花乙醇提取物和根的4种不同极性溶剂的萃取物均对斜纹夜蛾3龄幼虫具有触杀活性,并呈剂量依赖关系。根的乙醇提取物和根的氯仿萃取物触杀活性都很高,根的乙醇提取物在作用12 h后的LC50为413.56 mg/L,作用24 h的LC50为322.43 mg/L;作用虫体12 h后,根的氯仿萃取物质量浓度在5 000 mg/L和10 000 mg/L的校正死亡率均达到100%,LC50为738.00 mg/L,表明万寿菊杀虫活性物质主要存在于根中,且在氯仿溶剂中表现效果强。该研究可为万寿菊的进一步开发利用及研制杀虫剂提供理论依据。

The bio-activity on the 3rd instar larvaes of Spodoptera litura of different extracts of Tagetes erecta was tested by immursion method in the laboratory,and the highest insecticidal part was screened out.The bio-activity was evaluated after 12 h,24 h and 48 h,with concentration of 625,1 250,2 500,5 000 and 10 000 mg/L,water as CK,using ethanol extracts of marigold flowers,stems,leaves,roots and petroleum ether,chloroform,ethyl acetate extracts and insolubles of marigold roots.The results suggested that all the flowers,stems,leaves,roots and four polar parts of marigold roots had strong contact activity against the 3rd instar larvaes of Spodoptera litura,and in a dose-dependent manner,especially the ethanol extracts and chloroform extracts.The LC50 were 413.56 mg/L and 322.43 mg/L of the ethanol extracts of root after an exposure time of 12 h,48 h,respectively.The activity of chloroform extracts with concentration of 5 000 mg/L and 10 000 mg/L was the strongest,both the corrected mortality rate reached 100% and the LC50