Infection of red imported fire ant (Hymenoptera: Formicidae) colonies with the entomopathogen Thelohania solenopsae (Microsporidia: Thelohaniidae)

Abstract

Thelohania solenopsae Knell, Allen, and Hazard is an entomopathogenic microsporidium that infects imported fire ants. We documented artificially initiated transmission of T. solenopsae among colonies of the red imported fire ant, Solenopsis invicta Buren. Microsporidian transmission was initiated by providing colonies with brood (mixture of eggs, larvae, and pupae) from infected S. invicta colonies. Inoculated laboratory colonies of S. invicta had significantly less brood and adults than control colonies; after 23-29 wk, there was at least 88% less brood in the inoculated colonies. Lower egg laying rates, queen weights, and queen survivorship was also documented from infected colonies. Thus, T. solenopsae slowly debilitates an S. invicta queen so that reproductive capacity diminishes and early death results. Artificial inoculations resulting in infection and spread of T. solenopsae among red imported fire ant colonies under field conditions was also demonstrated for the 1st time.