复方苦参植物素水剂对十字花科蔬菜几种害虫的活性及田间防效

The activity and effectiveness in field of matrine to main vegetable pests

室内毒力测定结果表明 ,复方苦参植物素对菜蚜 (若蚜 )、菜青虫有很高的毒力 ,LC50 分别为 1.0 2mg/L和 1.37mg/L ,对斜纹夜蛾幼虫的毒力较低 ,LC50 为 11.6 5mg/L。复方苦参植物素不杀斜纹夜蛾的卵 ,不影响卵的孵化率 ,但对初孵幼虫有较好的杀伤效果。斜纹夜蛾幼虫随着虫龄的增大 ,对复方苦参植物素的敏感性下降。复方苦参植物素 10 0mg/L ,斜纹夜蛾幼虫非选择性和选择性拒食作用分别为 96 .86 %和78.97% ,作用方式以触杀作用为主 ,胃毒作用为辅。田间试验表明 ,复方苦参植物素 2 0 0～ 30 0倍 ,对菜青虫和菜蚜的防效在 90 %左右 ,持效期 10d。

The result of the test in laboratory showed that the toxicity of matrine was very high (LC 50 as 1.02 mg/L and 1.37mg/L respectively) against Lipaphis erysimi (Kaltenbach) and Pieris rapae (L.) and low against Spodoptera litura (Fabricius) (LC 50 as 11.65mg/L). The matrine could not kill the eggs of Spodoptera litura, and the activity was large to young larvae but reduced with increase of larvae age. At 100 mg/L, the non-selective and selective antifeeding rate of Spodoptera litura larvae were 96.86 and 78.97% respectively. Contacting poison of matrine against Spodoptera litura was more than stomach poison. The result of trial in field indicated that control effect of matrine to Pieris rapae (L.) and Lipaphis erysimi (Kaltenbach) at 200～300 times was about 90% with the high effectiveness was maintained for 10 days.