Distribution patterns of imported fire ants (Hymenoptera: Formicidae) on a sheep and goat farm in Oklahoma.

Imported fire ant colonies were quantified in 1,000-m(2) circular subplots spaced approximately 125 m apart on a sheep and goat farm in Oklahoma. Social form (percent polygyny), mound density, cumulative above-ground mound volume, and average mound volume were subjected to multiple regression analyses to examine trends related to landscape metrics and habitat characteristics. Monogyne populations were spatially autocorrelated, and polygyne mounds tended to be smaller and more numerous. A model incorporating the effects of percent polygyny, canopy cover, and 1-d cumulative incident solar radiation explained 34% of the variation in mound density. Percent polygyny was not significantly related to cumulative mound volume, which provides a better estimate of overall ant biomass. A model incorporating the effects of 1-d cumulative incident solar radiation on the summer solstice, elevation, canopy cover, distance from cisterns, distance from water, and distance from trees explained 42% of the variation in cumulative mound volume. Monogyne mounds in areas that were flat and close to water in low-lying areas were largest. Results indicate that remotely sensed data in combination with publicly available U.S. Geological Survey data may be useful in predicting areas of high and low fire ant abundance at a field scale.