Evidence of Selective Mating and Triploidy among Two Social Forms of Solenopsis invicta (Hymenoptera: Formicidae)

Abstract

A number of important behavioral and physiological traits distinguish both social forms of Solenopsis invicta Buren (Hymenoptera: Formicidae) and correlate with the Gp-9 locus within a supergene complex. These traits include fat body content, number of colony queens, dispersal, ability to initiate new colonies, size of workers, selective mortality, etc. Previous studies suggested gene flow between both social forms is unidirectional, with monogyne males mating almost exclusively with polygyne females. This study examined the genotypes of queens and their stored sperm during a mating flight in Florida where polygyne colonies predominate, and provides evidence of non-random mating; 84.6% of inseminated polygyne queens were mated to males of their own social form, and 92.4% of inseminated monogyne queens were mated by haploid males from monogyne colonies. Fertile, diploid males with unreduced sperm may be a cause for the high frequency of triploid BB alates (26.7%) and triploid polygyne alates (33.3%), and for some portion of all alates storing sperm that exhibited 2 microsatellite alleles (15.8%).