Observations on the life cycle of Coelomomyces indicus (Blastocladiales: Coelomomycetaceae) in anopheline mosquitoes from the Philippines and Thailand.

The water mold Coelomomyces indicus Iyengar is a widespread pathogen of anopheline mosquitoes in Asia and Africa, and it infects the copepod Microcyclops varicans Sars as its crustacean alternate host. This was determined by direct observation of field-infected copepods, selective meiospore encystment on M. varicans, and experimental infections of the copepod with zoospores from both thick and thin-walled meiosporangia. The physiological conditions governing germination of the 2 sporangial types were determined. The gametothallus in the copepod displays a light yellow pigmentation at maturity, and gametogenesis in both field and experimentally infected copepods occurs just at night fall, or 24 h after dark induction. In vivo culture was attained with the mosquito host Anopheles culicifacies Giles. Attempts to infect Anopheles stephensi Liston and Anopheles gambiae Giles, reported hosts of C. indicus, were unsuccessful.