Development of an Enzyme-Linked Immunosorbent Assay for Detection of the Gregarious Hymenopteran Parasitoid Muscidifurax raptorellus in House Fly Pupae

Muscidifurax raptorellus (Kogan and Legner) are gregarious parasitoids of stable fly (Stomoxys calcitrans L.) and house fly (Musca domestica L.) puparia. Strategic inundative releases of mass-reared M. raptorellus and other microhymenopteran parasitoids have been used in studies of biological control of pest and hemophagic dipterans that develop in livestock waste. Lack of an accurate and simple method to estimate pupal parasitism rates has limited the assessment of the utility of filth fly biological control by M. raptorellus and other parasitoids. Conventional estimates of parasitism rates are based on measurements of both the emergence of adult wasp parasitoids from puparia and the noneclosion of adult host flies (assuming parasitoid-induced pupal mortality). Microdissection of dipteran pupae for parasitoid presence is a difficult and tedious alternative method to estimate parasitism rates. In the present study, we produced polyclonal rabbit anti-M. raptorellus larvae serum antibodies, absorbed the antiserum with house fly puparia homogenates to remove muscoid host-reactive antibodies, and used the absorbed antiserum in a rapid enzyme-linked immunosorbent assay (ELISA) to detect M. raptorellus larvae in parasitized house fly pupae. The ELISA accurately detected M. raptorellus parasitism of house fly pupae between 7 and 21 days poststing and detected parasitoids in nonemergent house fly pupae. Absorbed antiserum specificity for parasitoid antigens was confirmed by Western blots. This first report of muscoid pupal parasitoid detection by enzyme immunoassay suggests that this approach has potential as a research and surveillance tool for monitoring and quantifying the success of parasitoid releases for biological control of dipteran pests.