Preference for straight-line paths in recruitment trail formation of the Argentine ant, Linepithema humile

Abstract

Linepithema humile (Mayr, 1868) ants self-organize mass recruitment to food sources by laying pheromone trails to direct foragers. Initial exploration may occur randomly, but selection of the shortest route is often derived from positive feedback mechanisms rather than individual intelligence or decision-making. In this study, we examined whether L. humile foraging routes minimize travel distance and maximize linearity (i.e., have the fewest turns). Colonies of L. humile foraged in an artificial grid containing a number of possible routes to a long-lasting food source. In the design, there were three possible shortest routes that varied only in the number of turns that the ants had to make. The majority of foraging ants preferred one of the three shortest routes to the food, and significantly favored the path with the fewest turns. Selection of the shortest, straightest route may maximize mass recruitment to the food source by decreasing the chance of foraging ants losing the trail.