DPT and gram-negative bacterial infections: Here, we have characterized the immunological role of three PGRP family genes, BdPGRP-LB, BdPGRP-SB1 and BdPGRP-SC2, after inoculation with the Gram-negative bacterium E. coli in B. dorsalis. After applying RNAi methods to knock down BdPGRPs followed by Gram-negative bacterial infection, Dpt, a marker of IMD pathway activation, showed a significant increase compared with the ds-egfp group.