  To date, the mechanisms underlying the diversity of the emergent patterns of
collective motion in locust hopper bands remain to be unveiled. This study
investigates the role of speed heterogeneity in the emergence of the most
common patterns (frontal and columnar), following the Self-Organization
framework. To address whether marching activity intermittency and
density-dependant hopping individual behaviours could underlie the formation of
such patterns, a three-zone Self-Propelled Particles model variant was
formulated. In this model, individuals alternated between marching and resting
periods, and were more likely to hop when crowded. The model successfully
predicted the emergence of both patterns of interest, with the presence of a
density-dependent hopping probability being a necessary condition. Short to
absent pause periods mostly resulted in columnar shapes, similar to the ones
observed in the brown locust (Locustana pardalina) and long pause periods
rather resulted in frontal shapes, such as exhibited by the Australian plague
locust (Chortoicetes terminifera). Furthermore, the density profiles of
simulated frontal formations displayed the same shape as empirical profiles of
Australian plague locust hopper bands. Both simulated and experimental paint
marking experiments showed that locusts initially located at different
positions in the band were find together at its front after a few hours
marching; an expected global behavior in hopper bands undergoing activity
intermittency. These results represent an important first step towards a
cross-species comparison of locust mass migration patterns.
