Field releases of the decapitating fly Pseudacteon curvatus (Diptera: Phoridae) for control of imported fire ants (Hymenoptera: Formicidae) in Alabama, Florida, and Tennessee

The little decapitating fly, Pseudacteon curvatus Borgmeier, was released at 11 sites in Alabama, Florida, and Tennessee as a potential self-sustaining biocontrol agent of imported fire ants. We used a biotype from Buenos Aires Province, Argentina that parasitizes black fire ants (Solenopsis richteri Forel). Generally, several thousand flies were released as larvae in parasitized ant workers over a 1-2 week period. Pseudacteon curvatus flies were successfully established on hybrid fire ants (Solenopsis invicta x Solenopsis richteri) at a site near Talladega, Alabama where they have persisted more than two years and expanded out 5-20 km from the original release site. Flies failed to establish in Florida and Tennessee although a few 1st-generation field-reared flies were recovered at four sites in Florida. This fly is only the second parasitoid species to be successfully released against imported fire ants or any other pest ant species. Possible reasons for failures at the other sites include insufficient vegetation cover, competition with another Pseudacteon species in Florida, severe winter kill of ants at a site in Tennessee, and the possibility that the biotype of P. curvatus released was not a viable parasitoid of red imported fire ants.