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 c olonies of the black imported fire ant, Solenopsis richteri Forel, and the presence of the microsporidian disease Thelohania solenopsae Knel l, Allen, & Hazard in Buenos Aires Province, Argentina. We compared vo lumes of infected colonies with those of healthy colonies within an ar ea where infected colonies were common and with those of healthy colon ies from an area free of the infection. We also compared presence of p olygyny, numbers of queens, presence and abundance of sexuals, broods, and myrmecophiles. Mound volume of infected colonies was substantiall y smaller than that of healthy colonies from the same area and from th e disease-free area (4.9 versus 14.7 and 18.7 liters, respectively). P olygyny, number of queens per colony, presence of worker broods, and p resence of winged females and males did not differ significantly in in fected and healthy colonies. Sexual broods were less frequent in infec ted than in healthy colonies (17 versus 37%, respectively). Presence o f myrmecophiles was as frequent in infected as in healthy colonies, bu t the bug Blissus parasigaster (Bergroth) was more numerous in infecte d colonies. T: solenapsae may be a good candidate for the biological c ontrol of imported fire ants in the United States.