Document: RON-3-99-114

Quantitative movement kinetics of workers and food among mounds of polygyne fire ants: Solenopsis invicta (Hymenoptera: Formicidae).

WEEKS, JR., R.D.*, L.T.WILSON, S.B.VINSON, J.S.JOHNSTON and X.WU

Texas A&M University, College Station, TX 77843-2475 USA ¹

Abstract:
The presence of multiple queens (polygyne) within ant mounds has several alternate consequences in the morphology, reproductive biology, social organization, and ecology of many ant species. Multiple queen colonies have been described as groups of cooperating unrelated families within and among mounds. Many pest ant species tend to polygynous. Previous studies have established that there is movement of food, workers and queens among polygyne fire ant mounds. Yet, the number of mounds, or the area that is occupied by a single polygyne colony has not been demonstrated. The objectives of this study were to quantify the movement of workers and food resources among polygyne fire ant mounds. We used mass-marking and recapture techniques to follow the movement of workers from one mound to neighboring mounds in the field. We found that the movement of workers to other mounds followed an exponential decay curve and that most of movement occurred within 1 meter from a mound. We used Neutron Activation Analysis (NAA) of six rare earth elements mixed with food bait to quantify the rate and extent of food sharing among polygyne fire ant mounds in the field. We fed ants in each of six mounds a food bait (sugar water and powdered egg yolk) mixed with a unique non-radioactive activatable rare earth element (i.e. Europium, Lanthanum, Neodymium, Rubidium, Samarium, and Ytterbium). We collected ants every 12 hours for 10 minutes from each mound by placing a pitfall trap in the center of each mound. The results of our food study show that the movement of food among mounds didn't follow an exponential decay model and that the final distribution of food resources was significantly skewed more towards one or two mounds than other mounds. These results suggest that the distribution of food resources among polygyne fire ant mounds is more complex than a simple function of distance and that there may be some nest specialization or dominance among mounds in the field. These are new and important findings on resource allocation and population dynamics of polygyne fire ants. This type of knowledge can be used to develop new management strategies to reduce polygynous pest ant populations, such as the red imported fire ant, which is a major environmental, economic and health pest in the Southeast United States.

Keywords: polygyne

This abstract is being presented at: 3:30 PM in session:
ANIMAL ECOLOGY