Access to shared food resources is key to the division of labour in honey bees

Division of labour plays a pivotal role in animal societies and it is one of the causes of success of eusocial insects. In honey bees, temporal division of labour implies that younger bees are involved in brood care, while older bees forage for nectar and pollen. Despite intense research the full chain of causes and effects leading to the temporal division of work in honey bees hasn’t yet been resolved. Here we show that endogenous factors drive the acceptance of honey bees in the brood area and thus their access to a nutrient rich diet; the diet in turn influences the aptitude to nursing. The transition to foraging results from the gradual displacement of the aging bees from the brood area by their younger nestmates, and thus their qualitatively inferior diet and the obliged choice of the riskier outside activities. Our results support the view that both reproductive and temporal division of labour in honey bees are dictated by nutrition as affected by dominance interactions among nestmates. The proposed model is consistent with an evolutionary trajectory implying a double decoupling, disjoining three functions primitively performed in cycles by the same solitary bee: oviposition, brood care and food collection. Behavioural observations and molecular studies shed light on the proximate and ultimate causes of division of labour in honey bees and contribute to a better understanding of this fundamental feature of animal societies.