Bio-efficacy Evaluation of Beauveria bassiana Against Fall Armyworm, Spodoptera frugiperda (J.E. Smith)

The fall armyworm (Spodoptera frugiperda J. E. Smith) (Lepidoptera: Noctuidae), a highly destructive polyphagous pest, invaded India in 2018 and has since rapidly spread across the country, causing extensive damage to maize. Farmers predominantly use chemical insecticides to manage this pest, but their effectiveness is often limited due to the pest’s concealed feeding habits, which prevent adequate contact with the chemicals. Moreover, the over-reliance on chemical controls has raised concerns about pesticide residues, environmental contamination, and associated health risks. To explore a safer and more sustainable alternative, an in-vitro bioassay was conducted to assess the virulence of the entomopathogenic fungus Beauveria bassiana (NBAIR strain) against second-instar larvae of S. frugiperda. Larvae were exposed to varying concentrations of B. bassiana (ranging from 5×105 to 3.65×107 conidia/ml). The highest mortality (84%) was observed at the highest concentration (3.65×107 conidia/ml), while the lowest mortality (10.41%) occurred at the lowest concentration (5×105 conidia/ml) at 120 hours post-inoculation. The lethal concentration (LC50) of B. bassiana against third-instar larvae of S. frugiperda was estimated at 1.42×107 conidia/ml, with fiducial limits ranging from 2.48×105 to 8.15×108 over 120 h. This study highlights the potential of B. bassiana as an effective biological control agent for managing fall armyworm populations, offering a viable alternative to conventional chemical insecticides.