Does ovarian ecdysone stimulate mosquitoes to synthesize vitellogenin?

Physiological amounts of 20-hydroxyecdysone do not initiate vitellogenin synthesis in unfed, non-vitellogenic mosquitoes. Injecting more than 10,000 times the physiological amount induced synthesis, but considerably less than was induced by a blood meal. A dose of 20-hydroxyecdysone which exceeded the physiological level only several hundred times, did not sustain vitellogenin synthesis, when blood-fed mosquitoes were ovariectomized just prior to injection. Transplanting ovaries from vitellogenic to non-vitellogenic females did not initiate synthesis of vitellogenin in the recipient. In vitro, neither 20-hydroxyecdysone nor the ovaries of vitellogenic females were able to induce synthesis of vitellogenin in non-vitellogenic fat bodies. These experiments suggest that ecdysteroid, released by the ovaries, does not initiate ovarian development in mosquitoes.