FACTORS AFFECTING LOAD SELECTION AND WORKER DIVISION IN THE FORAGING CASTE OF ATTA CEPHALOTES

This study examines factors affecting worker division and load size in Atta foragers. I tested the hypothesis that as Atta age, their mandibles wear down causing them to change from predominantly cutting and carrying leaves to carrying leaves cut by other individuals.. Physical restrictions on cutters limit the leaf fragment size they are able to cut. My hypothesis predicts that foragers cutting and carrying will have predominantly sharper mandibles and cut fragments that closely match their body size. Foragers only carrying will have more individuals with worn mandibles, and fragments that do not match their body size. I located three Atta colonies, and collected 20 carriers and 20 cutters per colony. I weighed the ant and leaf to determine if the interaction between ant weight and ant type and its effect on leaf mass was significant. A strong positive correlation between leaf mass and ant mass was found in foragers carrying, but there was essentially no correlation in foragers cutting. I measured the mandible lengths and first tooth lengths of both the left and right mandibles to determine if the interaction between ant type and mandible length and its effect on first tooth length was significant. A strong positive relationship was found between first tooth length and mandible length. However, this relationship was the same in both the carriers and the cutters indicating the interaction between mandible length and ant type and its effect on first tooth length was not significant