Project Summary Mosquitoes are well recognized as the most important arthropod vectors of disease-causing pathogens. This is because most species are anautogenous and must feed on the blood of a human or other vertebrate to produce eggs. Multiple cycles of blood feeding and egg development in turn favors frequent contacts with hosts, which makes mosquitoes ideal vectors for pathogen transmission. Since disruption of egg production also disables pathogen transmission, understanding the reproduction of anautogenous mosquitoes is an important area of study. This application is a renewal request to continue our work on how egg development is regulated. Our current award focuses on Aedes aegypti, which is the primary vector of the pathogens that cause Dengue Fever, Zika Virus syndrome and several other human diseases. Our studies indicate that two neurohormones, ovary ecdysteroidogenic hormone (OEH) and insulin-like peptides (ILPs) function as key regulators of the egg development process. The overall goal of this application is to understand how ILP and OEH signaling are tuned to regulate the different processes required for egg production. The studies we propose are innovative because they will be the first to link receptor binding preferences to the function of different ILP family members and OEH. Proposed Specific Aims are to: 1. Characterize the expression and receptor binding properties of different ILP family members and OEH. 2. Characterize the pre- and post-vitellogenic functions of ILPs and OEH. 3. Identify the factors that link nutrient acquisition after blood feeding to ILP and OEH release. Expected outcomes will enhance understanding of how egg formation is regulated in mosquitoes. Our study will significantly impact the field of vector biology by identifying new potential targets for disrupting female reproduction.