Germination rates of Beauveria bassiana and Metarhizium anisopliae its possible correlation with virulence against Spodoptera litura larvae

The present study reports relationship between rate of conidial germination of the two entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and their virulence against the insect pest Spodoptera litura larvae. Rate of germination in terms of TG50 (Time taken for germination of 50% of conidia) was estimated by calculating the germinated and ungerminated conidia at every 2 hour intervals up to 48 hours from the SDAY plates inoculated with 3x106 conidia/ml. Virulence of Beauveria bassiana and Metarhizium anisopliae was elucidated by performing bioassay with S. litura larvae at 2nd instar stage. The study demonstrated that the strains of both B. bassiana and M. anisopliae with low TG50 values were more virulent towards S. litura larvae, there by paving the way to use germination assay as an aid for screening the fungal strains for virulence.