Ovary Ecdysteroidogenic Hormone Stimulates Follicle Cell Proliferation Independently of the Insulin Receptor in Aedes aegypti Ovaries

The yellow fever mosquito Aedes aegypti transmits numerous viruses, filarial worms, and other pathogens that cause disease in humans and animals. Insecticides remain a prominent means of mosquito population control, but the spread of resistance to these chemicals necessitates further knowledge of biological processes that could be control targets, such as reproduction. Processes such as ecdysteroid production and follicle cell proliferation are essential for females to reproduce, and are promising targets for control.  Ovary ecdysteroidogenic hormone (OEH) and insulin like peptides (ILPs) stimulate ecdysteroid production.  Since OEH stimulates ecdysteroid production in female mosquitoes, and follicle cells produce ecdysteroids, we hypothesize that OEH stimulates follicle cell proliferation. Ovaries of non-blood fed female mosquitoes were incubated in amino acid rich media with OEH and stained for EdU to determine follicle cell proliferation.  Ovaries incubated with ILP3 were a positive control.  We also assessed whether OEH stimulated cell proliferation involved insulin and Target of Rapamycin (TOR) signaling, as does ILP3.  Ovaries were incubated with OEH or ILP3 and either OSI-906 or Torin 2, which are potent inhibitors of insulin and TOR signaling, respectively.  OEH stimulated follicle cell proliferation in ovaries and relies on TOR pathway activation, but not insulin receptor activation.