Fire ants abandon the foraging when their pheromone trail is perturbed

Southern Fire ants (Solenopsis xyloni) extensively use short-term pheromone trails to recruit nestmates towards food sources to retrieve food back to the nest. Individual workers can face several perturbations that can severely affect their foraging. This study aimed to investigate what mechanisms individual S. xyloni workers use to maintain their foraging when their pheromone communication is perturbed. We utilized the robustness categorization framework from the systems biology to develop multiple alternative hypotheses in regards to how ants will respond to such a perturbation. We perturbed the pheromone trail by removing a small portion of the trail on a T-maze setup. We recorded the proportion of ants making correct choices, the proportion of ants abandoning the perturbed trail, and the average gaster angle of ants to quantify pheromone trail laying. Significantly more ants abandoned the perturbed pheromone trail compared to unperturbed ones. Ants that did manage to make a choice on the T-maze despite the perturbed trail did not make significantly more correct choices compared to wrong ones. Moreover, the gaster angle of ants in the perturbed treatment was higher than the ants in the unperturbed treatment, indicating that the ants do not reinforce the perturbed trail. Overall, ants abandon the perturbed trail to contain the perturbation to avoid amplification of an outdated social signal, and thus maintain overall collective foraging. Further experiments would focus on understanding if a change in the perturbation or the resource type would change the strategies used by ants to maintain their collective foraging.