Worker nutrition and division of labour in honeybees

We determined whether there is an association between nutritional state (as indicated by stored abdominal lipid amounts) and division of labour in the honeybee, Apis mellifera. We found that foragers (typically older bees) had lower lipid amounts than did nurses (typically young bees). Results from experimental colonies that contained nurses and foragers of the same age showed that the lipid decline in foragers was not attributable to age. Analysis of bees with different amounts of foraging experience revealed little effect of the act of foraging on lipid stores. Lipid levels were low even on the first day of foraging, suggesting that the decline in stored lipid precedes the onset of foraging. We also found that bees that revert from foraging to nursing did not regain their lipid stores, indicating that high lipid stores are not required to sustain brood care behaviour. This demonstration of a robust association between reduced lipid stores and the transition to foraging suggests that worker nutritional state may be involved in the regulation of division of labour in honeybee colonies.