DISTRIBUTION OF THE FORMOSA STRAIN OF THE FIRE ANT DECAPITATING FLY PSEUDACTEON CURVATUS (DIPTERA: PHORIDAE) THREE AND A HALF YEARS AFTER RELEASES IN NORTH FLORIDA

The Formosa biotype of the decapitating fly Pseudacteon curvatus Borgmeier was released and successfully established as a self-sustaining biocontrol agent of the red imported fire ant Solenopsis invicta Buren at several sites around Gainesville, FL in 2003. In order to determine the status of these releases, 59 sites were surveyed for flies in the fall of 2006 with sticky traps and aspirators. Results of this survey showed that the flies had expanded outward an average of 74 km and occupied more than 30,000 km(2) in North Central Florida. This rate of expansion was faster than rates reported for Pseudacton tricuspis Borgmeier in Florida, Louisiana, and Texas. The rapid rates of expansion and high densities reported for the Formosa biotype of R curvatus indicate that it is a vigorous parasitoid which will require relatively fewer field releases to establish it as biocontrol agent of red imported fire ants in the United States.