Virulence Screening and Molecular Characterization of Beauveria bassiana Isolates Against Larvae of Spodoptera frugiperda, mention abstarct head

Abstract

The fall armyworm, Spodoptera frugiperda, is a highly destructive insect pest causing severe yield losses in several economically important crops worldwide. The increasing resistance of this pest to synthetic insecticides has intensified the need for environmentally sustainable biological control agents. The present study investigated the virulence potential and molecular characterization of different Beauveria bassiana isolates against larval stages of S. frugiperda. Fungal isolates were collected from diverse ecological regions and evaluated under laboratory conditions through pathogenicity bioassays. Larval mortality, median lethal time, and infection symptoms were recorded to determine the effectiveness of each isolate. Considerable variation in virulence was observed among the tested isolates, with certain strains causing significantly higher larval mortality and faster infection rates. Microscopic observations confirmed fungal colonization and mycosis in infected larvae. Molecular characterization was performed using internal transcribed spacer (ITS) region analysis and sequence comparison to confirm species identity and assess genetic diversity among isolates. Phylogenetic analysis revealed close genetic relationships among highly virulent strains while also indicating moderate genetic variability within the population. The integration of virulence screening and molecular identification provided reliable information for selecting efficient fungal isolates for biological control programs. The findings demonstrate that specific B. bassiana isolates possess strong entomopathogenic potential against S. frugiperda larvae and may serve as promising eco-friendly alternatives to chemical pesticides in integrated pest management strategies.