QUEEN DIMORPHISM AND REPRODUCTIVE STRATEGIES IN THE FIRE ANT SOLEPOPSIS-GEMINATA (HYMENOPTERA, FORMICIDAE)

Alate trapping studies of a monogyne population of the fire ant Soleno psis geminata indicate that two sizes of gynes are produced. Macrogyne s, which participate in late spring and summer mating flights, are lar ger, fattier, and more than twice as heavy as microgynes, which partic ipate in fall mating flights. Three patterns of gyne production were o bserved in 51 colonies studied: 35 produced macrogynes only, 9 produce d microgynes only, and 7 produced both morphs, contributing to both su mmer and fall mating flights. Behavioral evidence and rearing studies suggest that macrogynes found new colonies independently, whereas micr ogynes achieve colony queen status by infiltrating or being adopted by established colonies. Of the total number of female alates collected from the trapped colonies, 56% were microgynes. However, because of th eir smaller size and lower fat content, microgynes made up only one-th ird of the caloric investment in female alates. By measuring the thora x lengths of queens from mature colonies, we determined that at least 56% were macrogynes and 35% or more were microgynes. These results ind icate that as a reproductive strategy, colony investment in microgyne production may have at least as high a payoff as investment in macrogy ne production.