Susceptibility of Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) to Field Rates of Selected Cotton Insecticides²

The parasitoid Cotesia marginiventris (Cresson) was treated topically with minimum recommended field rates of formulated insecticides commonly used in cotton insect control. The 14 insecticides were acephate, azinphosmethyl, bifenthrin, cyhalothrin, cypermethrin, endosulfan, esfenvalerate, fipronil, methomyl, methyl parathion, oxamyl, profenofos, thiodicarb, and AC 303,630. Eleven of the 14 insecticides were extremely toxic to C. marginiventris, causing 80 to 100% mortality of adult wasps, whereas treatment with thiodicarb, oxamyl, and acephate resulted in lower mortality of C. marginiventris males and females. For both male and female C. marginiventris, thiodicarb and oxamyl were less toxic than acephate. Esfenvalerate was the least toxic pyrethroid for C. marginiventris females. Of the three insecticides used in boll weevil control (oxamyl, azinphosmethyl, and methyl parathion), oxamyl was the least toxic to C. marginiventris. Selective use of the insecticides which result in higher survival could facilitate conservation of C. marginiventris.