Occurrence and Seasonal Abundance of Parasitoids Attacking Muscoid Flies (Diptera: Muscidae) in Caged-Layer Poultry Facilities in New York

Abstract

Five species of house fly pupal parasitoids, Nasonia vitripennis Walker, Muscidifurax raptor Girault and Sanders, Pachycrepoideus vindemiae (Rondani), Spalangia sp., and Apanteles carpatus (Say), were recovered from house fly pupae exposed in controlled-environment, caged-layer poultry facilities during a 17-mo New York statewide survey. Overall, rates of parasitism were low, ranging from 0.2% in early spring to 14.0% in the fall. The number of fly pupae attacked by N. vitripennis was significantly higher than those killed by the other parasitoid species. Of all parasitized pupae collected in 1981, 76.9% were killed by N. vitripennis . In 1982, N. vitripennis was responsible for killing nearly 94.8% of all parasitized pupae. N. vitripennis was also the most abundant parasitoid, accounting for 95.5 and 99.2% of all parasitoids emerging from sentinel pupae during 1981 and 1982, respectively. In addition, N. vitripennis was the only parasitoid species observed to actively parasitize fly pupae in these facilities during cold winter months when temperatures in the first-floor manure pits ranged from 12 to 16°C. All the other parasitoid species generally were active only during warm summer months.