Noise-induced stability of insect swarms
Flying insect swarms exhibit cohesion without the local velocity alignment observed in flocks of birds or schools of fish. The interaction rules and channels of communication between insects that lead to collective behavior have not yet been determined. We propose a theoretical model based on acoustic communication between swarm members, where each individual is attracted to a weighted mean field of its neighbors. We demonstrate that this simple framework can describe a wide range of swarming dynamics, including a phenomenon where pairs of insects break free from the swarm in a helical orbit around each other. Counterintuitively, our numerical model suggests that stochastic noise enhances the stability of an insect swarm, as it interferes with pair formation. Finally, we demonstrate that a specific species of malarial mosquito produces swarms that reside on the edge of a transition to instability. Our study shows that fairly simple local interaction rules can be sufficient to describe the collective behavior of swarming biological systems.