What is fed to honeybee larvae for them to develop into queens?

A simple meal is all needed to determine a honeybee larva’s fate. It turns out that fragments of genetic material from flowers in their food control the bees’ destinies. When female larvae are fed royal jelly, which is secreted by other bees, they develop into large-bodied, fertile queens. But most larvae eat beebread, a mixture of pollen and nectar. These larvae develop into smaller, sterile worker bees.

Source: New Scientist