In Tenebrio molitor, upon infection, the recognition of Lys-type peptidoglycan (PG) (gram-positive bacteria) or β -1,3-glucan (fungi) and DAP-type PG (gram-negative bacteria) by PGRP-SA/GNBP1 or PGRP-LE/LC activates a serine protease cascade. Here, PGLYRP1 is linked to infection.