Toxicity of some insecticides for crowded and isolated nymphs ofGryllodes sigillatus Wlk. (Orthoptera: Gryllidae)

Summary 6 insecticides; chlordane, malathion, fenitrothion, pyrethrum, rotenone and sevin, were screened againstGryllodes sigillatus Wlk. reared under crowded and isolated conditions. Chlordane was found to be most toxic, followed by malation, fenitrothion, pyrethrum, rotenone and sevin. Insects reared under crowded conditions were more susceptible to insecticides than insects reared under isolated conditions.Acknowledgments. The authors are grateful to Dr S. C. Saxena for providing all facilities.