Efficient pheromone navigation via antagonistic detectors
Chemotaxis to a potential mate who is moving and emitting a volatile sex pheromone poses a navigation challenge that requires rapid, precise responses to maximize reproductive success. We demonstrate that Caenorhabditis elegans males address this challenge by utilizing two pheromone detectors located in head and tail sensory neurons. Despite sharing a receptor SRD-1, AWA head neurons promote forward movement and acceleration, while tail PHD neurons induce reversals and deceleration. In increasing pheromone gradients AWA dominates; whereas weakening gradients inactivate AWAs, allowing PHDs to fine-tune the response and correct the path. Head AWAs are essential for mate-searching, while tail PHDs are crucial for complex tasks. The navigation mode and velocity adapt as males climb a pheromone gradient. A minimal-parameter computational model recapitulates key findings and illuminates the interplay between head and tail signals in adaptive navigation.