| Popis: |
In a series of studies over a 4-year period, the effectiveness of releases of pteromalid wasps for the control of house flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.), on beef cattle confinements was evaluated using sentinel house fly pupae (artificially reared and placed in the environment) and naturally occurring house fly and stable fly pupae. The two methods were compared using percentage parasitoid emergence and species composition. At confinements where no parasitoid releases occurred, parasitoid emergence was significantly higher from naturally occurring hosts. Muscidifurax zaraptor Kogan and Legner comprised 97 and 76% of the parasitoids recovered from sentinel and naturally occurring hosts, respectively. Spalangia spp. made up 16% of the parasitoids from naturally occurring hosts. Few Spalangia spp. were recovered from sentinel hosts. Similar results were obtained from locations where M. zaraptor was released except that M. zaraptor comprised a greater proportion of the parasitoids recovered by both methods. At locations where Spalangia cameroni Perkins was released, 76% of the parasitoids recovered from sentinel hosts were M. zaraptor, and 21% were S. cameroni, compared with 62% M. zaraptor and 34% S. cameroni from naturally occurring hosts. At locations where Pachycrepoideus vindemiae (Rondani) was released, this species was recovered significantly more often from sentinel hosts. Naturally occurring pupal method appears to be more reliable and sensitive to the entire parasitoid species complex. However, because of the difficulty in obtaining adequate samples, it is recommended that both methods be employed. |
