RESUMO
Several species of fungi are currently being considered for operational use in the microbial control of mosquito larvae. The oomycetous fungi are the prominent ones amongst them because of their ability to complete life cycle in water. During our studies on zoosporic fungi from riverine waters of Mula and Mutha flowing through Pune City, Maharashtra, India, Aphanomyces laevis de Bary (Oomycetes: Saprolegniales) was isolated from polluted waters. After critical observations it was found to be mosquito larvicidal. Sporulating hemp seed cultures when inoculated under laboratory conditions revealed that it causes 80%/ mortality after seven days to Culex quinquefasciatus larvae. Laboratory assays were conducted to determine the effects of water quality on the ability of the isolate to infect mosquito larvae in varying degrees of pollution levels. In all the experiments, a non sexual strain of Aphanomyces (zoospores) was found to be the pathogenic agent for the Culex larvae.