Mating Bias In The Red Imported Fire Ant, Solenopsis Invicta

The two social forms in the red imported fire ant, Solenopsis invicta, are believed to be governed by the expression of one specific gene. This gene, known as Gp-9, is responsible for the production of general protein-9, thought to be a pheromone binding protein. Among the social aspects thought to be controlled by this locus is reproduction. Many aspects of breeding within and between the two colonial forms have been investigated over the past years since in introduction of this species to the United States. In this study, several features of the currently accepted model were examined. Newlymated queens were collected immediately after a mating flight in an area previously determined to contain both colony types. Analysis of the Gp-9 allele indicated a disproportionate number of monogyne queens, although there was not a discrepancy in the percent insemination of these queens versus their polygyne counterparts. This analysis also revealed the presence of an inseminated bb queen, once thought to be a fatal genotype, and an unexpected mating preference within colony type. This is especially interesting since the lack of fertile polygyne males is thought to necessitate the utilization of monogyne males for breeding in nearly all female alates. Fmiher microsatellite analysis indicated a relatively high number of triploid individuals and evidence of queens inseminated with two types of sperm. The latter could be due to multiple matings or the existence of diploid males with unreduced sperm. Each of these phenomena indicates the need for further study and potential modification of the standard model of fire ant breeding systems.