Sympatry of Polygyne and Monogyne Colonies of the Fire Ant Solenopsis invicta (Hymenoptera: Formicidae)

The polygyne form of the red imported Þre ant, Solenopsis invicta Buren, is thought to occur primarily in discrete populations embeddedwithin areas composed ofmonogyne colonies. This distribution implies that polygyne colonies competewithmonogyne colonies and subsequently create a population homogenous in social form. Because polygyne colonies produce mostly sterile males, opportunities for inseminationof female alatesmightbeminimal at the centers of largepolygyneareas. To test for homogeneity in social form, a large polygyne population described in northcentral Florida was examined for the presence of single queen colonies. Forty-six to 51 colonies were sampled from each of six sites located along an east-west transect through themiddle of the polygyne area inMarion County and a site at the northernmost limit of the polygyne area, Gainesville, FL. Several hundred workers from each nest were collected along with nest material. The social form of each sample was determinedbyanaggression test ofworkers to the introductionofnon-nestmates andby thedissection of males for sterility. Both social forms of S. invicta were present at all collection sites and 103 of 333 (30.93%) colonies sampledwere determined to bemonogyne colonies. Among the collection sites, the percentage of colonies that were monogyne ranged from 3.9 to 57.4%. The polygyne region in northcentral Florida is more accurately described as an area where relatively high frequencies of polygyne colonies are interdispersed with single queen colonies.