Abstract:The invasion of exogenous material may cause immunological and stress response in Ostrinia furnacalis Guenée larvae, and the antibacterial peptide (AP) could be induced. In order to further investigate the mechanism of AP, in this study, the pathogen of Escherichia coli was injected into 5th instar O.furnacalis larvae, and a novel type of antibacterial peptide was produced. The results showed that the antibacterial peptide with the relative molecular weight of 12.1kD was induced when the larvae was injected with E.coli cell at the concentration of 3.0×106 cell/mL. The expression of this antibacterial peptide increased with the inducing time from 12-36h. Both E.coli and Staphylococcus aureus could be inhibited by the antibacterial peptide. There was significant antibacterial activity when the antibacterial peptide was treated at 100℃ for 5min. The activity of the antibacterial peptide was the highest at the pH value of 8.0, and the diameter of inhibition zones was 6.9±0.3mm. This kind of antibacterial peptide has some heat, acidic and basic stability.