Abstract: Antimicrobial peptides (AMPs) are small molecular weight proteins with broad spectrum antimicrobial activity against bacteria, viruses, and fungi. In the present study, the real-time PCR and semi-quantitative RT-PCR were used to check the temporal and spatial expression patterns and the microbial sensitivity of genes of two very important antimicrobial peptides, moricin and cecropin, from Spodoptera litura to microbes. The real-time PCR result indicated that Moricin and Cecropin were expressed during the whole developmental stages, and the expression level increased with the development, with the highest expression level in the 6th instar larvae. The semi-quantitative RT-PCR result showed that both Cecropin and Moricin were expressed in the seven tissues including trachea, testis, Malpighian tubes, integument, midgut, fat body and hemocyte, and Cecropin had the highest expression level in fat body while Moricin had a relatively higher expression level in hemocyte. The temporal expression result detected by semi-quantitative RT-PCR showed that the expression of Cecropin and Moricin increased significantly within 48 h after induction with Escherichia coli, and reached the peak at 8 h after induction. Real-time PCR result showed that the transcript level of Moricin and Cecropin increased significantly after induction with different microbes (E. coli, Staphyloccocus aureus and Beauveria bassiana), respectively, and most sensitive to the induction of E. coli. The results of this study lay the foundation for further function research of Cecropin and Moricin from S. litura.

Key words: Spodoptera litura, antimicrobial peptide; Moricin, Cecropin, temporal and spatial expression profiles, microbial sensitivity