Effect of Insecticides on Tiphia vernalis (Hymenoptera: Tiphiidae) Oviposition and Survival of Progeny to Cocoon Stage When Parasitizing Popillia japonica (Coleoptera: Scarabaeidae) Larvae

The effect of insecticides on oviposition of Tiphia vernalis Rohwer and subsequent survival of parasitoid progeny to the cocoon stage was determined in the laboratory by using larval Japanese beetle, Popillia japonica Newman, as the host. Insecticides tested were imidacloprid, thiamethoxam, halofenozide, chlorpyrifos, and carbaryl at labeled rates. Female T. vernalis were allowed 2 d to parasitize P. japonica larvae after the parasitoids had received a 4-d exposure to insecticide-treated soil. Another group of female T. vernalis were allowed 2 d to parasitize P. japonica larvae that had been exposed to insecticide-treated soil for 3–4 d. Percentage of parasitism of P. japonica larvae in these trials after exposure of adult parasitoids to carbaryl, chlorpyrifos, halofenozide, or imidacloprid-treated soil (23.3–50.0%) or adult parasitoids to chlorpyrifos, halofenozide, or imidacloprid-treated grubs (33.0–56.7%) was not negatively affected relative to the control treatment (21.7–54.2%). A third grou...