Toxicity Assay and Pathogenic Process Analysis of Infecting .

has caused significant damage to pine forests, becoming a major biological disaster that hinders the sustainable development of forestry in China. To investigate the efficacy of biological control measures, entomopathogenic fungi were isolated and purified from the larvae of that had succumbed to diseases. The pathogenic capacity of strains was assessed using bioassay methods, and their infection process was observed using scanning electron microscopy. ITS, LSU, and TEF analysis disclosed as the highly virulent strain responsible for the death of . The optimal medium for its mycelial growth and sporulation was found to be PPDA. In addition, the bioassay revealed that the median lethal time (LT) for was 24.34 h and median lethal concentration (LC) was 2.35 × 10 conidia/mL, indicating that possesses potent virulence and demonstrates rapid pathogenicity. Furthermore, scanning electron microscopy demonstrated that initially entered the body of through the spiracle and progressively made its way into the body wall, resulting in the insect's death. The mode of infection for is exceedingly rare. As a consequence, the results of this study can serve as a reference for the management of chewing insects, such as .