Abstract: 【Aim】 To analyze and compare the structure of the bacterial communities in the midgut and hindgut of Protaetia brevitarsis larvae fed on Zea mays stalk, and to further explore the function of these gut bacteria in stalk digestion of this insect. 【Methods】 The total DNA was extracted from 10 samples of healthy gut bacteria (5 midgut contents and 5 hindgut contents) of the 3rd instar larvae of P. brevitarsis. The V4 region of 16S rDNA of the bacterial communities in the midgut and hindgut of P. brevitarsis was sequenced by Illumina HiSeq techniques, and the number of operational taxonomic units (OTUs), species composition abundance, alpha diversity and beta diversity were analyzed. The gut bacteria community data were mapped to KEGG genome database for further bacterial community function discovery. 【Results】 Totally, 1 062 897 high quality reads of gut bacteria of the 3rd instar larvae of P. brevitarsis were produced and clustered to 2 441 OTUs, which were annotated into 27 phylums, 51 classes, 77 orders, 168 families and 326 genera. At the genus level, Pseudomonas and Desulfovibrio were the most dominant genus in the midgut and hindgut, respectively. Alpha diversity data showed that the bacterial communities in the hindgut were more abundant than those in the midgut, and the beta diversity analysis indicated that the bacterial communities in the hindgut were more stable than those in the midgut. Function analysis of bacterial communities showed that both the bacterial communities in the midgut and hindgut contained stalk degradation enzymes, and the lignin degradation pathways were more abundant in the midgut while the cellulose degradation enzymes more abundant in hindgut. 【Conclusion】 The structure and characteristics of the bacterial communities in the midgut and hindgut of P. brevitarsis larvae fed on corn stalk were clarified, and their functions in helping P. brevitarsis digest stalk were discovered. These results will provide references for the further study on stalk digestion mechanism of this insect, and offer a new idea for utilization of crop straw resources in China.

Key words: Protaetia bevitasis, gut bacteria, 16S rDNA, V4 region, bacterial community, community diversity, function analysis