Chilodonella uncinata – As Potential Protozoan Biopesticide for Mosquito Vectors of Human Diseases

Abstract

Use of microbial control agents provide alternative method to synthetic pesticide for adequate insect management. Naturally occurring microorganisms such as viruses, bacteria, fungi and protozoa are used as biopesticides. Earlier studies revealed among entomopathogenic protozoa two ciliates, viz.: Lambornella clarki and Chilodonella uncinata are known with many biological control properties.This article addresses the current status of development of Ch uncinata sand formulation which is available in dormant stage in easy formulation and packed in sachet as "infusion bag" (easy to store, transport and treat with shelf life >18 months) to be used as potential biopesticide for mosquito vector of human diseases.During the process there were many questions like: (1) Ch uncinata culture should not be kept in refrigerator. But formulation prepared using the same culture tolerant to extreme cool weather. Reason: Ch uncinata has 4 stages in life cycle of which Trophont, the free living infective stage (in culture) is sensitive to cold; Cyst, the dormant stage (in the formulation) is tolerant to extreme cold situation. (2) Without artificial nutrition medium the culture remains in good condition for a few days when kept in Sun. Ch uncinata (trophont stage) has a chlorophyll particle in its body. (3) All the colonized mosquito larvae were highly susceptible to freshly prepared Ch uncinata strain at VCRC. Later these larvae at VCRC were found highly resistant to the same strain (sub-cultured repeatedly for a month). Due to repeated sub-culturing, Ch uncinata had lost their virulence. This was perhaps the same reason when a graduate student failed to induce infection in colonized larvae when both Ch uncinata and Culex pipiens were reared together. The student came out with a publication stating that Cx pipens was resistant to Ch uncinata which was found to be pathogenic to mosquito larvae elsewhere.