The frequency of leaf transfer in Atta cephalotes along horizontal and vertical surfaces near the bases of trees

Abstract

Leaf transfer is a specific type of task partitioning in leafcutter ants defined as the passing of fragments between two ants (direct transfer) or dropping leaf fragments along the trail for others to pick up later (indirect transfer). While research on leaf transfer has been conducted along horizontal paths, we aimed to discover how traveling down a tree may change this behavior in the leafcutter ant, Atta cephalotes. We conducted an observational study that compared the frequency of leaf transfer on the trunk, at the base of the tree, and on the ground of Atta cephalotes foraging trails. For direct transfer, there were no significant differences in mean transfer frequency among trail sections. However, mean indirect transfer frequency was significantly affected by trail section, with ants engaging in significantly less indirect transfer on the trunk of trees, and more at the base. This suggests that leaf caches at the bases of trees are primarily a consequence of indirect transfer at the base and not on the trunk. The observed increased transfer at the base also suggests that ants treat the base of the tree as a trail junction, similar to those between novel and established trails.