royalsocietypublishing | Impulsivity, the widespread preference for a smaller and more immediate
reward over a larger and more delayed reward, is known to vary across
species, and the metabolic and social hypotheses present contrasting
explanations for this variation. However, this presents a paradox for an
animal such as the honeybee, which is highly social, yet has a high
metabolic rate. We test between these two competing hypotheses by
investigating the effect of hunger on impulsivity in bees isolated from
their social environment. Using an olfactory conditioning assay, we
trained individuals to associate a small and a large reward with or
without a delay, and we tested their choice between the two rewards at
different levels of starvation. We found an increase in impulsive
behaviour and an associated increase in dopamine levels in the brain
with increasing starvation. These results suggest that the energetic
state of an individual, even in a eusocial group, is a critical driver
of impulsivity, and that the social harmony of a group can be threatened
when the energetic states of the group members are in conflict.
