杀虫剂对甜菜夜蛾不同世代及幼虫龄期的毒力变化

The toxicity of insecticides to S.exigua different in generations and instars was tested by topical application. The results that the toxicity of alpha cypermethrin, methomyl, profenofos, and chlorfluazuron to 4th instar was decreased among second, fourth and sixth generations, and that of alpha cypermythrin, methomyl, profenofos, and chlorfluazuron to third, fourth and fifth instar of sixth generation was also decreased. These gave a viewpoint that the resistance develops very quickly with the generations and instars increasing.