In order to establish symbiotic host-bacterial relationships, symbionts in insects evolved a mechanism to overcome host immune responses. Here we provide the resistance of symbiotic bacteria on the insect immune system. As a result, through the transposon mutagenesis, we found a salivary gland (SG) susceptible mutant. The disrupted gene was identified as nlpB involved in lipoprotein synthesis. The nlpB, bla double deletion mutant was sensitive to SG like nlpB-Tn5 inserted mutant. This mutant increases outer membrane permeability. It provides an explanation for SG susceptibility, because the antimicrobial peptide in SG would be able to translocate across the outer membrane more easily than in the wild type. These results indicate that nlpB and bla are likely to be important factors in terms of determining resistance against SG of Riptortus that is connected with the successful colonization of the Riptortus midgut.