Individual rules for trail pattern formation in Argentine ants (Linepithema humile)

Abstract

We studied the formation of trail patterns by Argentine ants exploring an empty arena. Using a novel imaging and analysis technique we estimated pheromone concentrations at all spatial positions in the experimental arena and at different times. Then we derived the response function of individual ants to pheromone concentrations by looking at correlations between concentrations and changes in speed or direction of the ants. Ants were found to turn in response to local pheromone concentrations, while their speed was largely unaffected by these concentrations. Ants did not integrate pheromone concentrations over time, with the concentration of pheromone in a 1 cm radius in front of the ant determining the turning angle. The response to pheromone was found to follow a Weber's Law, such that the difference between quantities of pheromone on the two sides of the ant divided by their sum determines the magnitude of the turning angle. This proportional response is in apparent contradiction with the well-established non-linear choice function used in the literature to model the results of binary bridge experiments in ant colonies (Deneubourg et al. 1990). However, agent based simulations implementing the Weber's Law response function led to the formation of trails and reproduced results reported in the literature. We show analytically that a sigmoidal response, analogous to that in the classical Deneubourg model for collective decision making, can be derived from the individual Weber-type response to pheromone concentrations that we have established in our experiments when directional noise around the preferred direction of movement of the ants is assumed.

final version, 9 figures, submitted to Plos Computational Biology (accepted)

Cited by in corpus (15)

• A common rule for decision-making in animal collectives across species
• Discrete modes of social information processing predict individual behavior of fish in a group
• Diversity Improves Speed and Accuracy in Social Networks
• The entropic basis of collective behaviour
• Analysis of emergent patterns in crossing flows of pedestrians reveals an invariant of `stripe' formation in human data
• The optimal geometry of transportation networks
• Bayesian decision making in human collectives with binary choices
• Balancing building and maintenance costs in growing transport networks
• Network-based model of the growth of termite nests
• Spontaneous trail formation in populations of auto-chemotactic walkers
• Modeling tropotaxis in ant colonies: recruitment and trail formation
• The Emergence of Lines of Hierarchy in Collective Motion of Biological Systems
• Mathematical models for chemotaxis and their applications in self-organisation phenomena
• How initial distribution affects symmetry breaking induced by panic in ants: experiment and flee-pheromone model
• Efficiency and shrinking in evolving networks