Abstract: Insecticidal activities of Polygonum orientale L.were seldom reported at home and abroad and the action ways of extracts from P.orientale against Mythimna separate Walker has not been investigated up till now.Study on insecticidal activities and action ways of the extracts can provide theoretical basis for formulating new type of botanical insecticides.The paper conducted insecticidal activities of extracts from P.orientale and their action ways against M.separate using immersion and sandwich methods.The results show that the extracts from seeds and stems in autumn had the highest effects and the contact mortality of methanol extract(diluted 5 times) against the 5th instar larvae of M.separate were 21.18% and 20.29%,respectively.Among the different solvent extracts,the ethanol extract from seeds had the strongest contact effect against the larvae,the adjusted mortality was 41.97%;the adjusted mortality of the methanol extract from stems in autumn was 20.29%.The adjusted mortalities of ethyl acetate extract from seeds and stems in autumn were 88.89% and 59.20%,respectively;the values of LC50 were 8.6466 and 29.0484 g·L^-1(extracts).The contact mortalities of the two extracts(diluted 10 times) were all 100% against the 4th instar larvae of Pieris rapae L.The contact mortalities of ethyl acetate extract(diluted 5 times) from seeds were 70.27,87.5,and 90.00% against the 3rd instar larvae of Plutella xylostella L.,the fifth instar larvae of Helicoverpa armigera Hübner and Mamestra brassicae L.The ethyl acetate extract from seeds had stomach poisoning effect against the 3rd instar larvae and the adjusted mortality was 57.14%;the inhibition rate of ethyl acetate extract from stems in autumn against the 3rd instar larvae was 30.45%.

Key words: Polygonum orientale L., Extract, Insecticidal activity, Mythimna separate Walker, Action way

摘要： 采用虫体浸渍法和夹毒叶碟法等方法研究红蓼(Polygonum orientale L.)提取物杀虫活性及其对粘虫的作用方式,为利用该植物研制新型植物源杀虫剂提供理论依据。结果表明,红蓼的最高杀虫活性部位是种子和秋季茎秆,甲醇提取物稀释5倍液对粘虫(Mythi mnaseparate Walker)5龄幼虫的触杀死亡率分别为21.18%和20.29%。种子不同极性溶剂提取物的触杀作用以乙醇最强,校正死亡率可达41.97%;秋季茎秆则以甲醇最强,校正死亡率为20.29%。种子和秋季茎秆乙酸乙酯萃取物的触杀死亡率分别为88.89%和59.20%,二者的LC50值分别为8.6466 g(浸膏)/L和29.0484 g(浸膏)/L。种子和秋季茎秆乙酸乙酯萃取物稀释10倍液对菜粉蝶(Pieris rapae L.)4龄幼虫的触杀死亡率均达100%,种子乙酸乙酯萃取物稀释5倍液对小菜蛾(Plutella xylostella L.)3龄幼虫、棉铃虫(Helicoverpa armigera Hbner)和甘蓝夜蛾(Mamestra brassicae L.)5龄幼虫的触杀死亡率分别为70.27%、87.50%和90.00%。种子乙酸乙酯萃取物对粘虫3龄幼虫的胃毒死亡率可达57.14%,秋季茎秆乙酸乙酯萃取物对3龄幼虫的生长发育抑制率为30.45%。

关键词: 红蓼, 提取物, 杀虫活性, 粘虫, 作用方式