Automated monitoring reveals extreme interindividual variation and plasticity in honeybee foraging activity levels

Workers in many eusocial insect species show a phenomenon sometimes referred to as 'elitism', in which a small proportion of individual workers engaged in a task perform a disproportionately large fraction of the work achieved by the colony as a whole. This phenomenon has not been well studied for foraging behaviour in honeybees (Apis mellifera) because detailed observational studies of foraging activity have been limited by the difficulty of successfully tracking large numbers of individual workers. Here, we used radio frequency identification technology to monitor honeybee flight behaviour automatically and generate lifetime flight activity records for large numbers of individuals from multiple colonies. We observed a consistent skew in activity levels of honeybee foragers, similar to that reported in many other social insects. However, this skew was a consequence of modulation of foraging activity by environmental and social factors rather than the existence of a distinct group or subcaste of elite foragers. Individual responses to experimental manipulation of the foraging workforce confirmed that activity level was flexibly adjusted according to colony needs. These results demonstrate that elitism in insect societies can arise as the extreme of a stable spectrum of individual behavioural activity that allows the colony to respond easily to unexpected needs rather than relying on responses of a rigidly defined subgroup of workers.