Meeting Abstract
Leaf-cutter ants play an important role in maintaining the biodiversity of neotropical forests by cutting and transporting leaf fragments from the canopy to their underground colonies. After cutting the leaves, ants lift the fragments overhead and carry them for long distances over well-established foraging trails. Previous studies have demonstrated that larger ants carry heavier leaves and that larger loads decrease walking speed. However, little is known about the maximum limits of load carrying ability in leaf-cutter ants, particularly in relation to the size of the self-selected fragments they carry and the excess power reserves they maintain to overcome obstacles. By incrementally adding weights to leaf fragments carried by foraging ants, we examined the relationship between body mass and maximum lifting power. As the ants reached maximum load carrying ability, their stepping pattern changed: walking speed slowed, leg stance widened, and staggering increased. Maximum load carrying ability scaled isometrically with body size and leaf-cutter ants were able to carry 7.8 times their body weight. However, larger ants chose to carry leaf fragments that represented a lower proportion of their body mass compared to smaller ants. This suggests that larger ants have the capacity to carry heavier leaves than they normally select and that the mechanism by which leaf-cutter ants choose leaf fragments to transport is not optimized for maximum foraging efficiency.
