Toxicity of some insecticides against Bracon hebetor (Say): A potential Lepidopterous parasitoid

Six insecticides (endosulfan, Thiodon 35EC; triazophos, Hostathion 40EC; cypermethrin, Arrivo 10EC; indoxacarb, Steward 150SC, A-cyhalothrin, Boxer 2.5EC and spinosad, Tracer 240SC) which are commonly used against Helicoverpa armigera (Hubner), have been evaluated against the potential larval parasitoid Bracon hebetor (Say) for their suitability of release in the integrated pest management (IPM) in cotton crops. The experiment was done under laboratory conditions (27±3Co and 65 ±5% RH) by using freshly emerged (one day old) adults for bioassays using the vial method. Spinosad was proved to be the most toxic insecticide against B. hebetor, having the lowest LC50 (86.96 ppm after 12 h exposure; 77.97 ppm after 24 h exposure and 57.75 ppm after 48 h exposure) and LT50 (4.05 h) values. Spinosad also caused the highest percentage of mortalities ( 90%) of B. hebetor at field-recommended doses. However, all the tested insecticides caused above 70% mortality, particularly after 48 h exposure. The results reveal that spinosad should be used carefully in the management of H. armigera. The possible releasing time of B. hebetor after insecticidal sprays in the field is discussed.