In this study, except for the group treated with strain BbZ1, the PPO activity of D. sylvestrella larvae in the other strain-treated groups continuously increased from 6 to 48 h post-infection to resist B. bassiana infection, the GST activity in the larvae significantly increased after infection by various B. bassiana strains with a decrease only observed at 12 h post-infection by strain CGMCC3.2055, and the CarE activity in the larvae of the treatment groups with strains BbZ1, CFCC81428, and CGMCC3.2055 also continuously increased from 6 to 36 h post-infection. The gene discussed is PPOX; the disease is infection.