Effects of diet type, developmental stage, and gut compartment in the gut bacterial communities of two Cerambycidae species (Coleoptera).

The gut bacterial community of wood-feeding beetles has been examined for its role on plant digestion and biocontrol method development. Monochamus alternatus and Psacothea hilaris, both belonging to the subfamily Lamiinae, are woodfeeding beetles found in eastern Asia and Europe and generally considered as destructive pests for pine and mulberry trees, respectively. However, limited reports exist on the gut bacterial communities in these species. Here, we characterized gut bacterial community compositions in larva and imago of each insect species reared with host tree logs and artificial diets as food sources. High-throughput 454 pyrosequencing of bacterial 16S rRNA gene revealed 225 operational taxonomic units (OTUs) based on a 97% sequences similarity cutoff from 138,279 sequence reads, the majority of which were derived from Proteobacteria (48.2%), Firmicutes (45.5%), and Actinobacteria (5.2%). The OTU network analysis revealed 7 modules with densely connected OTUs in specific gut samples, in which the distributions of Lactococcus-, Kluyvera-, Serratia-, and Enterococcus-related OTUs were distinct between diet types or developmental stages of the host insects. The gut bacterial communities were separated on a detrended correspondence analysis (DCA) plot and by c-means fuzzy clustering analysis, according to diet type. The results from this study suggest that diet was the main determinant for gut bacterial community composition in the two beetles.