Parasitism rates of Muscidifurax raptorellus and Nasonia vitripennis (Hymenoptera : Pteromalidae) after individual and paired releases in New York poultry facilities

Commercially reared parasitoids were released into three high-rise, caged-l ay) er poultry houses: one house received only N, vitripennis Walker, the s econd house received only AI. raptorellus Kogan & Legner, and the third hou se received an equal ratio of both species. Overall, house fly parasitism b y M. raptorellus was never higher than 7% in any house. Most parasitism in the ill. raptorellus release house was attributed to N. vitripennis. Parasi tism of house fly pupae by M. raptorellus did not significantly increase du ring or after the 6-wk release period in the house that received both paras itoids. However, a depression in total parasitism was not detected when rel eases of the two species were made in this house.