双委夜蛾幼虫对不同类别杀虫剂的敏感性及中毒症状

为筛选防治农业新发害虫双委夜蛾Athetis dissimilis（Hampson）的有效药剂，采用浸叶法测定了其不同龄期幼虫对8类18种常用杀虫剂的敏感性，并观察了幼虫对不同药剂的中毒症状。结果表明:3~6龄双委夜蛾幼虫对辛硫磷、联苯菊酯、高效氯氟氰菊酯、溴氰菊酯、甲氨基阿维菌素苯甲酸盐、氯虫苯甲酰胺和溴氰虫酰胺的敏感性较高，LC50值为0.138 1~27.40 mg/L；3龄及4龄幼虫对毒死蜱、高效氯氰菊酯、氟啶脲、茚虫威和虫螨腈敏感性较高，LC50值小于22.63 mg/L，而5龄和6龄幼虫对上述药剂的敏感性均有所降低，LC50值大于38.13 mg/L；各龄期幼虫对甲基嘧啶磷、灭幼脲及新烟碱类杀虫剂的敏感性均较低，LC50值大于40.83 mg/L。双委夜蛾幼虫对不同类别杀虫剂的中毒症状存在差异，其中，经有机磷类、新烟碱类、吡咯类及齅；二嗪类杀虫剂处理后，幼虫表现为体表干燥、体壁皱缩；而经拟除虫菊酯类杀虫剂处理后幼虫表现为体壁柔软、充满体液。就生物活性测定结果而言，推荐溴氰虫酰胺、氯虫苯甲酰胺、辛硫磷、联苯菊酯、高效氯氟氰菊酯、溴氰菊酯及甲氨基阿维菌素苯甲酸盐等药剂可用于双委夜蛾的应急防治。

Sensitivities and toxic symptoms of Athetis dissimilis (Hampson) to different insecticides

To search for the effective insecticides against the newly discovered pest Athetis dissimilis, the sensitivities of A. dissimilis larvae at different instars to 18 insecticides (eight categories) were determined using leaf dipping method, and the toxic symptoms of A. dissimilis treated with different insecticides were also investigated. The results showed that instar larvae of A. dissimilis form 3^rd to 6^th were sensitive to phoxim, bifenthrin, lambda-cyhalothrin, deltamethrin, emamectin benzoate, chlorantraniliprole and cyantraniliprole with LC₅₀ values ranging from 0.138 1 mg/L to 27.40 mg/L. The 3^rd- and 4^th-instar larvae of A. dissimilis were sensitive to chlorpyrifos, beta-cypermethrin, chlorfluazuron, indoxacarb and chlorfenapyr (LC₅₀<22.63 mg/L), whereas the 5^th- and 6^th-instar larvae were less sensitive to all those insecticides (LC₅₀>38.13 mg/L). Different instar larvae of A. dissimilis were insensitive to pirimiphos-methyl, chlorbenzuron and neonicotinoids insecticides (LC₅₀>40.83 mg/L). Meanwhile, the toxic symptoms of A. dissimilis larvae differed with treatments of different insecticides. When the larvae were treated with organophosphorus, neonicotinoids, phenylpyrazole and oxadiazine insecticides, the integument of the larvae became dry and shrank. However, the integument of the larvae turned soft and overwhelmed with body fluid while they were treated with pyrethroids. The bioassay results demonstrated that cyantraniliprole, chlorantraniliprole, phoxim, bifenthrin, lambda-cyhalothrin, deltamethrin and emamectin benzoate could be considered as the emergency control insecticides to A. dissimilis.