Abstract
Social insects have two or more female castes that exhibit extreme differences in their reproductive capacity. The molecular basis of these differences is largely unknown. In honeybees the egg yolk protein vitellogenin (Vg), has acquired regulatory functions that go beyond reproduction, including the regulation of aging and task polyethism. Vg is synthesised in the fat body of both queens and workers and in the ovaries of queens. Here we show that Vg is also expressed in worker ovaries and that ovary activation and environmental cues (both social and diet) modulate Vg expression. Workers that are fed Royal Jelly have higher expression of Vg than those not fed Royal Jelly. Surprisingly, we find that Vg expression is not corelated with worker ovary activation, which suggests that Vg has non-reproductive functions in worker’s ovaries. We also find that Royal Jelly in the diet disrupts the expression of likely regulators of Vg expression: Vitellogenin receptor (VgR), Krüppel-homolog 1 (Kr-h1), DNA methyltransferase 3 (Dnmt3) and the Forkhead box O transcription factor (FoxO). These results therefore support the ‘reproductive grand plan hypothesis’, which argues that genes that had reproductive functions in solitary ancestors have been co-opted for social functions in social insects.