The fire ant, Solenopsis geminata (F.), like many members of the S. geminata species group, forms both monogyne (single-queen) and polygyne (multiple-queen) colonies. To further understanding of the costs and benefits associated with variation in queen number in fire ants, investigations of colony reproductive structure (i.e., the number of nestmate queens and variation in their reproductive output) were undertaken in a native polygyne population of this species. The number of queens per nest is estimated to be about 30, with a range of 3 to 90. In the laboratory, queens from polygyne colonies set up individually under monogyne conditions had a higher oviposition rate and produced about 50 times more sexual offspring than queens maintained under polygyne conditions. The reduced reproductive success of queens in polygyne colonies is not evenly shared among all individuals. About 40% of the egg-laying queens in these colonies are uninseminated and therefore able to produce only male offspring. However, these individuals produce largely nonviable eggs. Among inseminated queens there is variation in both oviposition rate and egg viability, which suggests that nestmates may differ significantly in their realized reproductive success over the short and possibly long term. The results are discussed with reference to the well-characterized reproductive structure of polygyne colonies of the red imported fire ant, S. invicta Buren, with which this native population of S. geminata shares many similarities.
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Edward L. Vargo (1993) studied this question.