Vitellogenin expression in the ovaries of adult honeybee workers provides insights into the evolution of reproductive and social traits

Social insects are notable for having two female castes that exhibit extreme differences in their reproductive capacity. The molecular basis of these differences is largely unknown. A protein that likely plays a key role in these differences is Vitellogenin (Vg), a powerful antioxidant and insulin-signalling regulator. Here we investigate how Royal Jelly (the major food of honeybee queens) and queen pheromone (a major regulator of worker fertility), affects the longevity and reproductive status of honey bee workers, the expression of Vg , its receptor VgR and associated regulatory proteins. We find that Vg is expressed in the ovaries of workers and that workers fed a queen diet of Royal Jelly have increased Vg expression in the ovaries. Surprisingly, we find that Vg expression is not associated with worker ovary activation. Our findings provide further support for the ‘reproductive ground plan hypothesis’ as Vg has acquired non-reproductive functions in honeybee workers.