Quit bugging me: The influence of parasitoid phorid flies on foraging in fire ant workers

Host-parasitoid interactions are complex. A parasitoid can change its host’s behavior by direct infection or simply by its presence in the shared environment. In the red imported fire ant (RIFA, Solenopsis invicta), workers display defensive postures to avoid potential parasitism when parasitoid fire ant decapitating flies (Pseudacteon spp.) hover above them. RIFA workers sense decapitating fly presence through visual, olfactory, and auditory cues. In addition to individual changes in behavior, RIFA colonies experience a shift to nocturnal foraging in the presence of decapitating flies. This shift is to compensate for lowered foraging during the day when the diurnal decapitating flies are active. We investigated the genetic factors related to nocturnal foraging behavior at the colony level. By quantifying expression of the RIFA foraging gene (sifor) of colonies exposed to decapitating flies and control colonies, we aimed to provide information into the molecular processes related to change in foraging behavior of RIFA. In RIFA, sifor is shown to correlate with worker task. In addition, odorant-binding protein 11 and hymenoptaecin (hym) will be investigated because they are hypothesized to experience varying expression between workers and nurses due to environmental differences (e.g., forager encounters with natural enemies). Colonies exposed to parasitoids are hypothesized to experience changes in genetic expression. We further hypothesize that RIFA exposed to decapitating flies experience reduction in the expression of sifor and hym. These results will provide us with information on how host-parasitoid interactions can impact the RIFA colonies.