How does royal jelly affect whether a larva becomes a queen or a worker?

In the context of honeybee development, royal jelly is the critical factor that determines whether a female larva matures into a queen or a worker bee. While all honeybee larvae are initially fed royal jelly, the duration and quantity of this diet dictate their eventual caste.12

• Worker Bees: Larvae destined to become workers are fed royal jelly only during the first three days of their development. After this period, their diet is transitioned to other substances.21
• Queen Bees: Larvae selected to become queens are fed royal jelly exclusively and copiously throughout their entire larval period.12

This continuous, nutrient-rich diet allows the selected larvae to develop into larger-bodied, sexually mature queens. To accommodate this growth, the worker bees enlarge and draw out the cells in which these future queens develop. This process is a natural mechanism used by the colony to propagate or replace a queen when the hive becomes crowded or the existing queen departs.1