The Control of Vitellogenesis in the Mosquito,Aedes aegypti

Evidence from several laboratories indicates that oogenesis in mosquitoes is divided into at least two discrete stages. First, emergence triggers development of the oocytes up to the resting stage where they remain until the blood meal. This stage is mediated by the juvenile hormone from the corpora allata. The second stage is triggered by the blood meal and involves the release of a hormone from the brain as well as the vitellogenin stimulating hormone (VSH) from the ovary. The mature oocytes then inhibit development of the penultimate oocytes until the first batch of eggs is laid. The evidence for an ovarian hormone, VSH, controlling vitellogenin synthesis by the mosquito fat body is reviewed. This hormone activates and maintains vitellogenin synthesis by the fat body in vivo and in vitro. The role of VSH in mosquito reproduction and the possibility of similar hormones in other insects is discussed.