This study sought to characterize biological functions of all B. bassiana Pr1 proteases by multiple analyses of single gene-deleted and rescued mutants, clarify which Pr1 proteases function in host infection and hence are essential for insect pathogenicity, identify conserved molecular marks of insect pathogenicity from the Pr1 family, and understand a significance of the conserved marks for the adaptation of B. bassiana to the broadest host spectrum. This evidence concerns the gene TMEM37 and infection.