Toxicity of insecticides to red pumpkin beetle on sweet gourd leaf

Red pumpkin beetle Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) is a major devastating insect pest of sweet gourd. The larva and adult stages of this beetle are injurious to sweet gourd plants. Several groups of insecticides are applied by the farmers in Bangladesh to control this insect pest. However, the efficacy of these insecticides in field and laboratory conditions have not been assessed in Bangladesh. In this study, the efficacy of the frequently used insecticides namely, Cyren 20 EC, Marshal 20 EC, Ripcord 10 EC and Orogard 55 EC were evaluated to control adult red pumpkin beetles. The mortality rates of the beetles at 24, 48 and 72 hours after application of the insecticides ranged from 14.4 to 46.7%, 33.3 to 73.3% and 52.4 to 86.7%, respectively, and the results differed significantly. Among the tested insecticides, only Orogard 55 EC with recommended dose revealed statistically higher mortality rate (86.7%) of the beetle at 72 hours after treatment, and the computed toxicity data (LC50 and LC95 ) were 7260 ppm and 8323.4 ppm, respectively. Cyren 20 EC, Marshal 20 EC and Ripcord 10 EC with recommended doses revealed very lower rates of mortality and showed toxicity at very high concentrations, indicating that the beetle has developed resistance to these insecticides.