How memory and motivation modulate the responses to trail pheromones in three ant species

Abstract

Ants are able to modulate their behavior according to private and collective information. Collective information is coded in different concentrations of pheromone deposited in the environment, especially on ant trails, whereas private information is learned and memorized by individual ants. It has been shown that both kinds of information act synergistically on the collective trail-following behavior of ant colonies. Another important factor influencing ant behavior is their motivation to follow pheromone trails. Here, we show how private information and motivation modulate the response to collective information. We investigate these effects using a recently proposed approach that employs psychophysical methods to measure the response to varying pheromone concentrations. We studied the effect of private information (route memory) in the species Lasius niger, Euprenolepis procera, and Linepithema humile. Additionally, the effect of motivation was studied in the species E. procera and L. humile. Using psychophysical methods, we quantified these effects for important biological parameters like behavioral thresholds and error rates. The differential changes in these parameters between the three species imply specific adaptations to their environment.