Identification and entomopathogenicity of two novel Sarocladium species isolated from soil in China

The genus Sarocladium has traditionally been associated with plant endophytism and phytopathogenicity, and entomopathogenic activity has not previously been reported in this genus. In this study, two fungal strains isolated from soil samples collected in China were examined using morphological characterization and phylogenetic analyses to determine their taxonomic positions. Their insecticidal activity was further evaluated against third-instar larvae of Ostrinia furnacalis through laboratory bioassays. The two isolates were identified as two novel species, Sarocladium poyangense and S. jiangsuense, both of which formed distinct clades separate from their closest known relative, S. kiliense. Bioassays showed that both species were strongly pathogenic to O. furnacalis. Among them, S. poyangense exhibited higher virulence, causing 80% larval mortality at a spore concentration of 1 × 10⁸ spores/mL, with an LC₅₀ of 3.13 × 10⁷ spores/mL and an LT₅₀ of 6.08 days. These findings expand the known ecological role of Sarocladium by demonstrating, for the first time, its entomopathogenic potential, and suggest that this genus may represent a promising resource for the development of biological control agents against insect pests.