Effect of Foraging Trail Straightness on U-Turning Probability in Forager Pharaoh's Ants

摘要

Social insects commonly use shared information, such as pheromone trail networks of ant colonies to guide foragers to food and back to the nest. Foragers use shared information in choosing the right trail at a bifurcation, and U-turning after erroneous choices. We studied the effect of trail bends on U-turning in fed workers of the Pharaoh's ant Monomorium pbaraonis. Our results show that foragers returning to the nest from a food source along a non-branching freshly laid pheromone trail are much more likely to make U-turns when the trail zig-zags (55% of workers U-turn at least once), and especially when the trail doubles back on itself (92%), than when the trail is straight (8%). Thus, workers are not blindly following a pheromone trail, but are sensitive to information from both the angle of the trail bends, and the direction of successive bends. Workers avoid trail bends that are unlikely to lead to the nest.