Identification of the ovary ecdysteroidogenic hormone receptor in the yellow fever mosquito Aedes aegypti

Mosquitoes that transmit human pathogens require a blood meal to facilitate egg production.  This process is regulated by an endocrine cascade that begins with the release of insulin-like peptides (ILPs) and ovary ecdysteroidogenic hormone (OEH) from the medial neurosecretory cells of the brain.  These peptide hormones stimulate the ovaries to produce ecdysteroids, which induce synthesis of yolk protein by the fat body for uptake by oocytes.  Previously, we showed that ILP3 activates the insulin receptor expressed in the ovaries of this species.  However, no receptor has been characterized for OEH, a neuroparsin homolog found in most arthropods. Using comparative genomics, we identified an orphan receptor in the genome that is highly expressed in ovaries.  Subsequent experiments showed that RNA interference with its expression disrupted egg development in blood-fed females and ecdysteroid production by ovaries, which could be reversed by ILP3 but not by OEH treatment.  These results indicate that this orphan is the long sought receptor for OEH, a potent activator of mosquito reproduction.