Phorid Fly (Diptera: Phoridae) Oviposition Behavior and Fire Ant (Hymenoptera: Formicidae) Reaction to Attack Differ According to Phorid Species

Abstract

Phorid flies in the genus Pseudacteon affect the foraging and defensive behaviors of their host, the red imported fire ant, Solenopsis invicta Buren. Field observations of Pseudacteon species indicated interspecific variation in attack behavior. Here, we assess whether differences in attack behavior and ant response might assist in prioritizing species for biocontrol. We studied the oviposition behavior of eight phorid fly species and determined how attack by each influenced the normal behavior of the red imported fire ant. The fly species tested were: Pseudacteon borgmeieri Schmitz, P. curvatus Borgmeier, P. nudicornis Borgmeier, P. obtusus Borgmeier, P. solenopsidis (Schmitz), P. tricuspis Borgmeier, P. litoralis Borgmeier, and P. wasmanni (Schmitz). Of these, P. borgmeieri attack interfered with normal red imported fire ant worker behavior the most, whereas P. curvatus had the least effect. Because the supposed effectiveness of phorids as biocontrol agents depend on their ability to interfere with normal fire ant behavior, these results suggest that some species of phorids would be better candidates for biocontrol than others. Our results combined with results from other studies examining host specificity of phorids suggest that P. tricuspis and P. obtusus are excellent candidates for biocontrol of the red imported fire ant in geographical areas where polygyne colonies dominate, such as Texas. Conversely, where monogyne colonies dominate, such as Florida, P. litoralis should be considered.