title: Impact of Thelohania solenopsae (Microsporidia: Thelohaniidae) on polygyne colonies of red imported fire ants (Hymenoptera: Formicidae).
abstract: Three studies were conducted to assess the effects of the entomopathogen Thelohania solenopsae on polygynous, red imported fire ant, Solenopsis invicta Buren, colonies. A total of 57 of 122 queens (46.7%) from nine, field-collected, polygyne, S. invicta colonies, was infected with T. solenopsae. Infection rate of queens for each colony ranged from 25 to 75%. Laboratory colonies of polygyne S. invicta, with three to 12 queens, were inoculated and infected with T. solenopsae. Brood levels in all infected colonies declined to 0 after 26-52 wk. Brood did not reappear in any of the colonies after 3-11 wk, even though in two of the eight infected colonies, five fertile queens that were uninfected were recovered. Thus, polygyne, S. invicta colonies infected with T solenopsae, which were confined and isolated under laboratory conditions, did not recover. Field plots that contained polygynous S. invicta colonies, which were infected with T solenopsae, were monitored over a 2-yr period. Infection rates increased during the study and reached a maximum of 9.3%. Fire ant nest density and colony sizes fluctuated over time, with maximum reduction of 63% per plot. In general, fire ant reductions were attributed to smaller colony sizes. T. solenopsae infections in polygynous S. invicta can result in a slow colony decline and death. Under field conditions, the prolonged colony death may mask the impact of T. solenopsae by allowing for concurrent reinfestations.
authors.affiliation: USDA-ARS Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL 32608, USA. doi@gainesville.usda.ufl.edu
authors.forename: David H
authors.initials: DH
authors.lastname: Oi
authors.forename: David F
authors.initials: DF
authors.lastname: Williams
mesh_terms: D000818:Animals; D001000:Ants / Q000469:parasitology* / Q000502:physiology; D005260:Female; D016814:Microsporidia / Q000502:physiology*