Information integration for nutritional decision-making in desert locusts

Swarms of the migratory desert locust can extend over several hundred
square kilometres, and starvation compels this ancient pest to devour
everything in its path. Theory suggests that gregarious behaviour benefits
foraging efficiency over a wide range of spatial food distributions.
However, despite the importance of identifying the processes by which
swarms locate and select feeding sites to predict their progression, the
role of social cohesion during foraging remains elusive. We investigated
the evidence accumulation and information integration processes that
underlie locusts' nutritional decision-making by employing a Bayesian
formalism on high-resolution tracking data from foraging locusts. We
tested individual gregarious animals and groups of different sizes in a
2-choice behavioural assay in which food patch qualities were either
different or similar. We then predicted the decisions of individual
locusts based on personally acquired and socially derived evidence by
disentangling the relative contributions of each information class. Our
study suggests that locusts balance incongruent evidence but reinforce
congruent ones, resulting in more confident assessments when evidence
aligns. We provide new insights into the interplay between personal
experience and social context in locust foraging decisions which
constitute a powerful empirical system to study local individual decisions
and their consequent collective dynamics.