Locust collective motion in heterogeneous landscapes (#646)
Research into animal collective motion seeks to reveal the rules and mechanisms behind the emergent, self-organized behavior demonstrated by many organisms. Â Most studies have traditionally focused on interactions between the animals and their conspecifics, while the important interactions between the animals and their local environment have attracted less attention. Marching swarms of desert locust nymphs offer an ideal model to pursue this specific question, as they are highly interactive with the topography of the environment in which they march. We monitored the movement of crowd-reared five-instar nymphs in a ring-shaped arena. We then indented a portion of the ring to create a converging or diverging funnel that affected the movement of the animals, and compared the coordinated behaviors between different types of arenas (symmetric vs . asymmetric with different funnel sizes) .Â Using high temporal and spatial resolution analysis, we analyzed individual trajectories in order to obtain the impact of topography on the movement patterns of individuals and on the global properties of the swarm. Irrespective of the specific topography tested, the locusts demonstrated consistent coordinated marching. Moreover, we found a correlation between the order parameter (which quantifies the level of synchronization) and the marching speed. Â These findings add to a previously reported correlation with the fraction of walking animals. Other characteristics of individual behavior, such as the duration of walking bouts, were also affected. Future work is aimed at modeling locust behavior under changing environmental topographies. The expected results of the computer simulations, together with our experimental findings, may offer predictions regarding the behavior of locust swarms in the field and their adaptive behavior in different terrains.