Chilodonella uncinata - a protozoa pathogenic to mosquito larvae

During August 2001, repeated high mortalities observed in Culex tritaeniorhynchus and Cx. pseudovishnui mosquito larvae collected from paddy fields prompted me to detect the causative organism. A ciliated protozoan, Chilodonella uncinata, was found to cause chronic and fatal infection in the natural population of mosquitoes in and around Delhi, North India. Anopheline larvae were less (14.13%) susceptible to Chilodonella infection than culicine larvae (75.21%). Body cavities of dead and transparent larvae were found packed with thousands of motile endoparasitic stage of the ciliate. Numerous cuticular cysts were observed on cadaver of larvae and pupae. The use of cuticular cyst in differentiating ciliate genera pathogenic to mosquitoes is discussed. The limited study points to the biological control potential of Ch. uncinata against vectors of Japanese encephalitis.