Invasion of Aedes aegypti ovaries by Coelomomyces stegomyiae

Aedes aegypti (Diptera, Culicidae) larvae, infected with Coelomomyces stegomyiae (Chytridiomycetes, Blastocladiales), can pupate and eclose to produce adults that carry the fungal infection. In female mosquitoes, fungal hyphae in the hemocoel migrate to the ovaries during the pupal stage and the first 24 to 48 hr of adult life. Hyphae penetrate the ovaries in association with epithelial cells involved in tracheole production during ovarial expansion and maturation. Infected adult female mosquitoes, that have had a blood meal, have 46% lower 20-hydroxyecdysone titers and negligible levels of vitellogenin compared to that of equivalent healthy females. Hyphae of C. stegomyiae mature to resting sporangia in the ovaries of adult Ae. aegypti in response to increased titers of 20-hydroxyecdysone which follow a blood meal. In the absence of a blood meal, maturation of hyphae to resting sporangia in infected adults was induced by injection of 20-hydroxyecdysone.