Protein craving links larval signals to food provisioning in honey bees

The provisioning of royal jelly for developing larvae by nurse bees is fundamental to social interaction in honey bee colonies. While royal jelly production is regulated by collective larval demand, it remains unclear how colony-level needs are translated into individual worker behavior. Here, we show that the larval pheromone E-β-ocimene (EBO), a volatile compound also used by pollinators as a floral food cue, elicits an intrinsic craving for protein in nurse bees that drives increased pollen consumption. Through in vitro and in vivo experiments, we demonstrate that this response is mediated by the leucokinin (Lk) and leucokinin receptor (Lkr) system, acting through the PKA-CREB-IRS signaling pathway to modulate the expression of the insulin receptor substrate gene (Irs). Elevated pollen intake then promotes the enlargement of the hypopharyngeal glands and enhanced production of major royal jelly proteins. Our findings uncover a molecular mechanism linking larval signaling to worker nutrition, highlighting how social bonds between honey bee larvae and nurses are rooted in ancestral pathways of protein hunger that predate eusociality.