Patterns of host specificity in Pseudacteon parasitoid flies (Diptera: Phoridae) that attack Solenopsis fire ants (Hymenoptera: Formicidae)

Pseudacteon phorids that parasitize the red imported fire ant, Solenopsis invicta Buren, in South America are not present in the introduced range of this pest species in the United States. Sequential host specificity tests were conducted with 4 South American Pseudacteon species, P. litoralis Borgmeier, P. wasmanni (Schmitz), P. tricuspis Borgmeier, and P. curvatus Borgmeier, to investigate the degree to which these species attack the native North American fire ant, Solenopsis geminata (F.). Three species, P. litoralis, P. wasmanni, and P. tricuspis, showed little interest in ovipositing on S. geminata, even when highly motivated to oviposit on S. invicta. By comparison, P. curvatus oviposited on S. geminata readily. Larval development of P. curvatus did occur in S. geminata, but no adult flies emerged. Methods for assaying host specificity and the biocontrol potential of these unique insects are discussed.