A dietary phytochemical alters caste-associated gene expression in honey bees.

In the eusocial honey bee Apis mellifera, with reproductive queens and sterile workers, a female larva's developmental fate depends on its diet; nurse bees feed queen-destined larvae exclusively royal jelly, a glandular secretion, but worker-destined larvae receive royal jelly for 3 days and subsequently jelly to which honey and beebread are added. RNA-Seq analysis demonstrated that p-coumaric acid, which is ubiquitous in honey and beebread, differentially regulates genes involved in caste determination. Rearing larvae in vitro on a royal jelly diet to which p-coumaric acid has been added produces adults with reduced ovary development. Thus, consuming royal jelly exclusively not only enriches the diet of queen-destined larvae but also may protect them from inhibitory effects of phytochemicals present in the honey and beebread fed to worker-destined larvae.