Immature Development of <I>Pseudacteon tricuspis</I> (Diptera: Phoridae), an Endoparasitoid of the Red Imported Fire Ant (Hymenoptera: Formicidae)

Abstract

Many approaches are being tested to control the red imported fire ant, Solenopsis invicta Büren. Biological control through the use of parasitoids and parasites is promising. Among the parasitoids of these ants, Pseudacteon spp. (phorid flies) are receiving special attention. One of these species, Pseudacteon tricuspis Borgmeier, has been released in target areas for field assessments. However, there is not enough information about their biology or interactions with their hosts. Here we describe the parasitization and development of P. tricuspis in two sizes of ants. We also evaluated the behavioral response of these ants to the attack of this fly. We found no difference in the development of P. tricuspis when attacking small or large ants. The immatures showed similar developmental time and morphology in both groups of ants. The egg is laid in the thorax, and there are three instars before pupariation. The first instar develops in the thorax, and it remains inside its serosa after hatching. It molts into a second instar soon after leaving its serosa. Second and third instars develop in the head. Pupariation takes place inside the head of the host. Adults eclose ≈19 d after pupariation. We also discuss some of the possible physiological mechanisms involved in the host–parasitoid interactions, as well as in the interactions with conspecifics. The feasibility of developing in vitro rearing systems to culture this parasitoid is also addressed.