A Magnetic-like description of Oscillatory Behavior in Chemotactic Ants

We investigate the role of chemotaxis in the movement dynamics of Aphaenogaster Senilis ants. To do so, we design an experimental setup in which individual ants are exposed to a narrow pheromone trail to guide their motion. As expected, ants locate and navigate the trail by detecting chemical scents, exhibiting a characteristic zigzag pattern, moving at a nearly constant speed while oscillating perpendicularly to the trail. The zigzagging motion is common across many species yet its underlying mechanism remains unclear. Here, we propose a physical framework based on the Inertial Spin Model as an approach to quantitatively describe and explain this behavior. So, we implement chemotaxis resembling magnetic-like interactions between the ant's velocity and the pheromone gradient. Under specific approximations, the model yields an analytical expression for the velocity correlations perpendicular to the trail, predicting a characteristic oscillatory decay. This prediction closely matches our experimental data, suggesting that the model captures the essential ingredients of ant dynamics. By fitting the model parameters to individual experimental trajectories, we further explore their potential biological significance and validate our assumptions. Overall, our findings contribute to the understanding of chemotaxis in ant motion and its physical features.