Biolarvicidal activity of extracellular metabolites of the keratinophilic fungus Trichophyton mentagrophytes against larvae of Aedes aegypti - a major vector for chikungunya and dengue.

The larvicidal activity of extracellular metabolites of keratinophilic fungus Trichophyton mentagrophytes against Aedes aegypti larvae was determined. T. mentagrophytes was isolated from soil by the feather baiting technique. Culture filtrates (10-100 microL/mL) were found to be entomotoxic to 3rd instars larvae of A. aegypti (L3), LC(50) and LC(90) being 110 +/- 11.5 and 200 +/- 20.7 microL/mL, respectively, after 2 d. Extracellular metabolites are proteinaceous in nature and more specific to chitin of mosquito larvae. They degraded cock feather causing an average of 20.0 +/- 2.6 % loss in feather mass. Culture filtrate at 100 microL/mL produced 90 % mortality against L3 after 3 d; mortality was increased in dose- and time-dependent manner. These extracellular metabolites of T. mentagrophytes could be regarded as alternatives to synthetic insecticides.