A comparison of the colony-founding potential of queens from single- and multiple-queen colonies of the fire ant Solenopsis invicta

Newly mated queens from the polygyne (multiple-queen) form of S. invicta show a weight polymorphism that correlates with their genotype at the protein locus Gp-9. Although this variation in weight might be expected to translate into variation in the ability of queens to initiate new colonies using stored energy reserves, a systematic examination of the colony-founding ability of newly mated polygyne-derived queens of different weights has never been reported. Here I compare the ability of monogyne-derived queens (Gp-9BB M), heavy polygyne-derived queens (Gp-9BB P), and light polygyne-derived queens (Gp-9Bb P) to initiate their own colonies using only stored energy reserves. Most measurements of the ants' abilities yielded the following scale of competency: Gp-9BB M>Gp-9BB P>Gp-9Bb P. Surprisingly, most mated polygyne-derived queens of even the lighter genotype were capable of rearing considerable numbers of workers in isolation. This ability may be enhanced substantially in the field if such queens cooperate in initiating new nests (pleometrosis). These results are concordant with the growing body of work that implicates a simply inherited genetic polymorphism for the control of a complex social trait in this ant, and they indicate that the modes of reproduction in polygyne fire ants may show considerable diversity.