Abstract: 【Aim】 To clarify the community structure and diversity of bacteria in the intestine of Cnaphalocrocis medinalis (Guenée) larvae. 【Methods】 The V3-V4 regions of the 16S rDNA genes of intestinal bacteria in the 4th instar larvae of C. medinalis  were sequenced by Illumina MiSeq techniques. The numbers of sequences and operational taxonomic units (OTUs), species composition, abundance and diversity of the bacteria were analyzed using USEARCH and QIIME softwares. A total of 165 386 reads were obtained in the four samples consisting of 1, 2, 3 and 5 larvae of C. medinalis, respectively. 【Results】 After filtration, 604 OTUs were acquired and annotated into 22 phyla, 43 classes, 82 orders, 142 families, 204 genera, and 244 species. Common dominant bacteria based on phyla were Proteobacteria (relative abundance 26%-34%) and Actinobacteria (23%-32%). Actinobacteria (relative abundance 23%-32%), Acidobacteria (9%-11%), Alphaproteobacteria (10%-13%), Betaproteobacteria (6%-8%), Gammaproteobacteria (6%-12%) were dominant at the class level. Nocardioidaceae, Comamonadaceae, Xanthomonadaceae, Sphingomonadaceae, and Gemmatimonadaceae were commonly dominated at the family level in the bacterial communities from the four samples, and Nocardioides and Sphingomonas were the commonly dominated genera in the top 5 genera of bacterial communities from the four samples. The indices of Simpson, Shannon, Ace and Chao were 0.16-0.65, 0.94-3.22, 212-488 and 210-490, respectively. 【Conclusion】 The results indicate that there are diverse bacteria in the intestine of C. medinalis larvae, and there are differences in bacterial structure and diversity among intestines of C. medinalis individuals. The information from samples of different size and the total sample can promote the comprehensive understanding of the bacterial community in the intestine of C. medinalis population. The information of bacterial abundance and diversity in the intestine of C. medinalis will facilitate the studies on the new technology of its control based on the intestinal bacteria.

Key words: Cnaphalocrocis medinalis, intestine bacteria, diversity, 16S rDNA, gene sequencing