Reduced Foraging of Solenopsis geminata (Hymenoptera: Formicidae) in the Presence of Parasitic Pseudacteon spp. (Diptera: Phoridae)

The rate of food retrieval in Costa Rican colonies of the fire ant, Solenopsis geminata (F.), declines to near zero in the presence of parasitic phorid flies of the genus Pseudacteon Coquillett (Diptera: Phoridae) because virtually all workers assume a distinctive antiparasitoid defense posture. The presence of a single male parasitoid is sufficient to elicit defense behavior in 100 or more workers and significantly reduces food retrieval. We hypothesize that interactions between phorid parasitoids and South American fire ants lead to similar disruptive behavior. In contrast to some other researchers, we argue that phorid parasitoids are excellent candidates for biological control of imported fire ants.