COMPARISON OF POLYGYNE AND MONOGYNE RED IMPORTED FIRE ANT (HYMENOPTERA, FORMICIDAE) POPULATION-DENSITIES

Polygyne or multiple-queen colonies of red imported fire ant, Solenops is invicta Buren, are reported to be a substantially greater environme ntal and economic problem than monogyne or single-queen fire ants beca use of much higher population densities associated with polygyny. This study compared population densities of polygyne and monogyne fire ant colonies using measures of mound density, worker number ant biomass, metabolic consumption, and standing caloric energy of ant biomass. We began the experiment by counting and measuring mounds at 14 polygyne a nd 14 monogyne sites located within a 35-km radius of Gainesville,, FL . Average mound densities were 3.03 times larger at polygyne sites tha n at monogyne sites (470 versus 155 mounds per hectare). To adjust for differences in mound size, 22 monogyne and 21 polygyne mounds of vari ous sizes were excavated from 16 of the experimental sites. Colony siz e and biomass were regressed on mound volume. These regressions then w ere used to estimate colony size and colony biomass from the mound vol umes measured at the 28 field sites. The estimated colony sizes and co lony biomasses at each site were summed and used to estimate field pop ulation densities. Polygyne populations contained 1.94 times more work ers per unit area (35 million versus 18 million workers per hectare) a nd 1.86 times more biomass (27.7 versus 14.9 kg wet weight per hectare ) than monogyne populations. Energy usage and standing energy of the a nts per hectare were, respectively, 2.30 and 1.90 times higher in poly gyne populations. Overall, this study indicates that polygyne populati on densities are approximate to 2 times larger on average than monogyn e population densities.