Antimicrobial peptides play important roles in innate immunity and recovery from chill coma in Lasioderma serricorne

Antimicrobial peptides (AMPs) in insects are short peptides that play an important role in their innate defense system. The production of AMPs is typically induced by an infection of pathogenic microorganisms, but cold stress may also cause upregulation of insect AMP genes. However, little is known about the functions of AMPs in cold stress situations and the recovery afterwards. As most important results, in this project with Lasioderma serricorne that can tolerate long storage under cold conditions, we identified and investigated four AMP genes (LsAtt1, LsAtt3, LsCec and LsDef-like). We confirmed their anti-bactericide activity in in vitro assays and in RNAi assays. The cross treatments with cold stress showed that LsDef-like was upregulated under cold stress and its silencing caused a loss of survival. In contrast, the expression of the other three AMPs did not change, and their silencing prolonged the recovery time. We believe that our cross treatments, revealing an association between immune activation and cold stress with AMPs, will increase our basic understanding of the immune system and the “cross-talk” with cold resistance.