Sensory flexibility in the desert locust - from social cues to collective migrations

Locusts offer a powerful model for studying social plasticity and collective behavior. Adapted to extreme environmental fluctuations, they can rapidly transition between solitary, cryptic grasshoppers and swarm-forming gregarious ones. Despite their importance as a model system and the severe humanitarian consequences of locust swarms, the mechanisms underlying this behavioral plasticity and the initiation of swarming remain poorly understood. In this talk, I will present our work investigating the neural and behavioral basis of these transitions, focusing on the sensory representation of conspecifics and the local interaction rules that drive the onset of coordinated swarm movement. We find that crowding enhances olfactory sensitivity: gregarious locusts become more responsive to food odors in the presence of other locusts, an adaptation likely to facilitate foraging within dense swarms. When moving between feeding sites, gregarious locusts form cohesive groups in which visual cues from conspecifics are both necessary and sufficient to sustain coordination. Notably, while solitary and gregarious locusts both detect visual motion cues, only gregarious animals actively pursue them, suggesting a phase-dependent change in visual processing that promotes collective migration. By combining detailed behavioral analyses, transcriptomics, and neural mapping, we are dissecting the mechanisms that mediate these transitions. I will share current findings and outline future directions in our research on the proximate basis of swarm formation in one of the world’s most devastating pest species.