寄主植物和试虫龄期对斜纹夜蛾药剂敏感性的影响

采用浸叶法测定了取食芋、甘薯、白菜和空心菜4种不同寄主植物的斜纹夜蛾（Spodoptera litura）4龄幼虫对高效氯氟氰菊酯、毒死蜱、溴虫腈、甲氨基阿维菌素苯甲酸盐和氟虫腈的敏感性，比较了不同龄期幼虫对药剂的敏感性差异。结果表明：在取食的4种寄主植物中，斜纹夜蛾4龄幼虫对以上5种药剂敏感性最高的均为甘薯，敏感性最低的均为芋，取食白菜和空心菜的幼虫对药剂的敏感性无明显差异；不同龄期斜纹夜蛾幼虫对药剂的敏感性存在显著差异，2—4龄幼虫随龄期的增加，药剂敏感性逐渐下降。

Effects of host plants and pest instars on susceptibility of Spodoptera litura to insecticides

By means of leaf dipping method, the susceptibilities to insecticides by the 4th instar larvae of Spodoptera litura fed on different host plants were tested, and the variances in insecticide susceptibility among different instar lar- vae of S. litura were compared. The results showed that the susceptibility of the 4th instar larvae of S. litura fed on lpomoea batatas was highest and that on Colocasia esculents was lowest to/ambda-cyhalothrin, chlorpyrifos, chlorfena- pyr, emamectin benzoate and fipronil among the four host plants tested. No significant differences in the susceptibilities of the larvae fed on Brassica Campestris and Ipomoea aquatica to the above five insecticides were found. Insecticid- al tolerance of the larvae increased significantly from the 2nd to 4th instar stages.