Relative Abundance of Stable Fly and House Fly (Diptera: Muscidae) Pupal Parasites (Hymenoptera: Pteromalidae; Coleoptera: Staphylinidae) on Confinement Dairies in California

Abstract

Four dairies in southern California were sampled weekly from April 1987 through June 1988 to determine the distribution and relative abundance of stable fly, Stomoxys calcitrans (L.), and house fly, Musca domestica L., pupal parasites. Seven parasite species represented ≍90% of the parasites recovered from stable fly and house fly pupae, and included Spalangia endius Walker, Spalangia cameroni Perkins, Spalangia nigroaenea Curtis, Muscidifurax raptor Girault and Sanders, Muscidifurax zaraptor Kogan and Legner, Urolepis rufipes (Ashmead), and Aleochara spp. U. rufipes had not been previously recorded to parasitize these hosts in California. Most of the U. rufipes recoveries were between April and June. The relative abundance of parasites recovered from stable flies and house flies on four southern California dairies varied slightly for some species, but the overall rate of parasitism only ranged from 13.4 to 19.9%. A limited number of stable fly and house fly pupal collections from dairies in central California revealed a much lower proportion of S. cameroni and a higher proportion of S. endius , when compared with southern California dairies. The majority of stable fly and house fly pupae sampled at four southern California dairies were associated with pure manure substrates. There was no significant difference between the relative abundance of parasites recovered from stable fly pupae sampled from manure, manure plus hay, or wet-hay substrates. Significantly fewer S. nigroaenea and significantly more M. zaraptor were recovered from house fly pupae developing in brewer's grain when compared with manure, manure plus hay, and wet-hay substrates. In pupal samples which contained both stable flies and house flies, S. cameroni was recovered significantly more often from stable fly pupae. In general, there were no significant differences between stable fly and house fly in parasitism by the seven parasite species.