Lethal and sublethal effects of selected insecticides and an insect growthregulator on the boll weevil (Coleoptera : Curculionidae) ectoparasitoid Catolaccus grandis (Hymenoptera : Pteromalidae)

A laboratory culture of Catolaccus grandis (Burks), an ectoparasitoid of th e Loll weevil, Anthonomus grandis grandis Boheman, was exposed to lethal an d sublethal doses of insecticides and an insect growth regulator using a sp ray chamber bioassay. Materials tested were azinphos-methyl, endosulfan, fi pronil, malathion, cyfluthrin, dimethoate, spinosad, methyl parathion, acep hate, oxamyl, and tebufenozide. At full rates, spinosad was significantly l ess toxic to female C. grandis than other treatments except endosulfan. Fip ronil and malathion were significantly more toxic to females than other tre atments. Most of the chemicals tested were highly toxic to male C. grandis: spinosad was least toxic. At reduced rates, most of 4 selected chemicals t ested were low in toxicity to C. grandis; however, a reduced rate of malath ion was significantly more toxic to females than other treatments. No C. gr andis pupae developed from parasitism during a 24-h treatment period with m alathion or spinosad. The sex ratio of progeny from sprayed adults appeared to Le unaffected by the treatments.