Bees' royal jelly secret revealed

There's more than one way to turn a commoner into royalty. Honeybees create queens by feeding their larvae royal jelly, the secret ingredient of which has now been identified.






Masaki Kamakura of Toyama Prefectural University in Imizu, Japan, stored royal jelly at 40 °C for 30 days, feeding it to bee larvae at intervals. Its regal effect gradually weakened, suggesting the key ingredient was decaying. He then fed larvae deactivated jelly with each batch laced with a different compound that was subject to decay. Only one caused the larvae to turn into queens: a protein Kamakura calls royalactin.

To find out how royalactin works, Kamakura added it to the diet of fruit fly larvae. This made them grow larger and lay more eggs, as in bees. Kamakura found that royalactin works by switching on the gene that codes for Egfr, a protein found throughout the animal kingdom.

This suggests a pre-existing mechanism was repurposed to produce the bee caste system, says Francis Ratnieks of the University of Sussex in Brighton, UK. When insects first formed eusocial colonies, queens and workers must have been physically identical, he says, and the distinct castes came later, created by royalactin or something like it.