Do Pseudacteon phorid flies (Diptera: Phoridae) host feed on imported fire ants (Hymenoptera: Formicidae)?

Many parasitoid species are known to utilize resources from their host and plants for energy and reproduction. Pseudacteon phorid flies are introduced parasitoids of imported fire ants, Solenopsis spp., in the Southern United States. These flies are known to utilize sugar resources in the laboratory and field. However, it is unclear whether or not they host feed on ants. Recent studies by our group showed that field-collected P. curvatus contained significantly higher levels of lipid than detected in laboratory-reared sugar-fed individuals. Thus, we hypothesize that the high level of lipid detected in the field-collected flies was probably derived from host feeding. To test the hypothesis of host feeding by phorid flies, a series of biochemical tests were used to quantify and compare sugar and lipid levels in P. curvatus from five diet treatments: i) laboratory-reared sugar-fed flies provided access to ant pupae, ii) laboratory-reared sugar-fed flies provided access to dead ant workers, iii) laboratory-reared sugar-fed flies provided access to ant hemolymph, iv) laboratory-reared sugar-fed flies with no access to host materials, and v) field-collected flies. The ecological significance and practical implications of the results are discussed.