RELATIONSHIP BETWEEN COLONY SIZE OF SOLENOPSIS-RICHTERI (HYMENOPTERA, FORMICIDAE) AND INFECTION WITH THELOHANIA-SOLENOPSAE (MICROSPORIDA, THELOHANIIDAE) IN ARGENTINA

We studied the association between the size and composition of field colonies of the black imported fire ant, Solenopsis richteri Forel, and the presence of the microsporidian disease Thelohania solenopsae Knell, Allen, & Hazard in Buenos Aires Province, Argentina. We compared volumes of infected colonies with those of healthy colonies within an area where infected colonies were common and with those of healthy colonies from an area free of the infection. We also compared presence of polygyny, numbers of queens, presence and abundance of sexuals, broods, and myrmecophiles. Mound volume of infected colonies was substantially smaller than that of healthy colonies from the same area and from the disease-free area (4.9 versus 14.7 and 18.7 liters, respectively). Polygyny, number of queens per colony, presence of worker broods, and presence of winged females and males did not differ significantly in infected and healthy colonies. Sexual broods were less frequent in infected than in healthy colonies (17 versus 37%, respectively). Presence of myrmecophiles was as frequent in infected as in healthy colonies, but the bug Blissus parasigaster (Bergroth) was more numerous in infected colonies. T: solenapsae may be a good candidate for the biological control of imported fire ants in the United States.