Discrimination by the Pupal Parasite Spalangia cameroni (Hymenoptera: Pteromalidae) Between Live and Freeze Killed House Fly (Diptera: Muscidae) Pupae

Live house fly pupae were suitable as hosts for Spalangia cameroni Perkins at all age classes tested. However, no parasite emergence occurred from house fly pupae freeze-killed when 12 h old and very limited emergence occurred for pupae freeze-killed when 132 h old. Furthermore, significantly more parasites emerged from hosts that were alive when parasitized when compared with freeze-killed hosts parasitized under similar conditions. In choice experiments, S. cameroni exhibited a strong preference for live hosts over freeze-killed hosts at all parasite-to-host ratios. It does not appear that freeze-killed hosts will be useful as a survey tool or as a method for field propagation of S. cameroni as they are for other species of pteromalids.