Immature development of Pseudacteon tricuspis (Diptera : Phoridae), an endoparasitoid of the red imported fire ant (Hymenoptera : Formicidae)

Many approaches are being tested to control the red imported fire ant, Sole nopsis invicta Buren. Biological control through the use of parasitoids and parasites is promising. Among the parasitoids of these ants, Pseudacteon s pp. (phorid flies) are receiving special attention. One of these species, P seudacteon 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 Lye describe the parasitization and development of P tricuspis in two sizes of ants. We also evaluated the beha vioral response of these ants to the attack of this ny. We found no differe nce in the development of P. tricuspis when attacking small or large ants. The immatures showed similar developmental time and morphology in both grou ps of ants. The egg is laid in the thorax, and there are three instars befo re pupariation. The first instar develops in the thorax, and it remains ins ide its serosa after hatching. It molts into a second instar soon after lea ving its serosa. Second and third instars develop in the head. Pupariation takes place inside the head of the host. Adults eclose approximate to 19 d after pupariation. We also discuss some of the possible physiological mecha nisms involved in the host-parasitoid interactions, as well as in the inter actions with conspecifics. The feasibility of developing in vitro rearing s ystems to culture this parasitoid is also addressed.