Seasonal occurrence of the mosquito pathogenic fungus culicinomyces clavisporus in a natural habitat

A longitudinal study to investigate the natural hosts and occurrence of the mosquito pathogenic fungus, Culicinomyces clavisporus was conducted at the Nattai River, Mittagong, New South Wales. The fungus was isolated from Aedes rupestris on 16 occasions, Aedes rubrithorax on 1 occasion, Aedes sp. on 1 occasion, Dasyhelea sp. on 8 occasions, a Chironomidae larva on 1 occasion and moist sediment once. With the exception of 1 isolate, which was from an Aedes larva in a groundpool, all of the infected larvae were collected from small rockpools on a trachyte weir. The study indicated the fungus did not persist and recycle in those rockpools but was washed in when river levels rose. The occurrence of the fungus had a seasonal bias, with 24 of 28 isolates obtained in the cooler months of April to August. Possible reasons for this are discussed.