The role of Pseudacteon phorid flies in the foraging dynamics of red imported fire ants: resource size and nutrient composition selection

Pseudacteon phorid flies represent a potential mechanism for the biological suppression of red imported fire ant (Solenopsis invicta) populations in the United States, and elsewhere.  These flies are known to influence a reduction in the foraging intensity of S.invicta when they are present.  It is presumed that this curtailment of foraging during diurnal periods when phorids are active will shift the outcome of competitive interactions between S.invicta and native ant and arthropod species assemblages, in favor of the latter.  Since the introduction of phorids to the United States began, many previously unobserved S.invicta behaviors resulting from the interactions between these ants and phorids have been noted in the literature.  One such phenomenon is the shift from predominantly large, to relatively smaller S.invicta foragers in areas where phorids have become established.  This behavior led us to design a series of laboratory and field experiments to investigate the potential effects this shift might have on resource selection by S.invicta, including resource size and nutrient composition selection.  Trials were designed to allow observation of S.invicta selection of a continuum of resource sizes, as well as selection of resources which had been created with a variety of protein:carbohydrate ratios during periods of phorid activity and inactivity.  The data presented will demonstrate the selection tendencies of S.invicta with respect to resource size and nutrient content when simultaneously challenged by phorids.  From an applied biology perspective, such information could prove to be very important to the development of effective toxicant baits for suppression of S.invicta populations where phorids occur.