Combining social and private information: How ants use pheromones and learnt cues to navigate.

Ants exhibit remarkable navigational abilities, flexibly integrating private information such as path integration and learnt visual cues with social information in the form of trail pheromones. Far from being simple or rigid directional signals, pheromone trails serve diverse, context-dependent roles in navigation. For instance, they can act as scaffolds during early foraging trips, tethering naïve ants to the nest while they acquire spatial knowledge. Pheromones also function as reassurance signals, confirming that a forager is on the correct path, and as a fail-safe when other cues become unreliable. Additionally, they appear to support multi-vector way-pointing through gating part of the path integrator expression, enabling ants to segment complex routes and to leave and re-enter trails. The regulation of pheromone laying itself is also influenced by private information streams, including internal state, prior foraging success, and navigational memory, highlighting the nuanced interplay between individual experience, environmental cues, and social signals. Together, these findings reveal the trail pheromone is not merely a recruitment or directional signal, but is an integral component of a sophisticated, multimodal navigational system, interwoven with private memories and the individual's internal state to support flexible navigation.