Abstract: 【Objective】To clarify the structure and diversity of the bacterial composition of the larval intestine of the one-spotted stem borerParalipsa gularis (Zeller)and to predict its function,in order to provide a theoretical basis for the subsequent excavation of the functional bacteria in the intestine of the pest and the development of its integrated control strategy.【Method】Using P.gularis populations in Baoshan City and Mangshi City,Yunnan Province,isolated,identified and sequenced P.gularis 3^rd instar larval intestinal bacteria from two geographic populations using traditional isolation and cultivation methods combined with high-throughput sequencing technology,analyzed their composition and diversity.The expression of functional genes in the intestinal bacteria of P.gularis in different geographical populations was analyzed by KEGG metabolic pathway.【Result】The intestinal bacteria of 3^rd instar larvae of P.gularis populations in Baoshan in 23 phylums,48 classes,120 orders,211 families,375 genera,and the dominant genera were Enterococcus(38.02%) and Enterobacter (17.24%);a total of 10 species of culturable bacteria were isolated from 2 phyla,4 families,5 genera,and the dominant phylum,family,genera,and species were Firmicutes (72.73%),Bacillaceae (36.36%),Bacillus (36.36)%and Enterococcus gallinarum (45.34%) respectively.Mangshi P.gularis larval intestinal bacteria had6 phylums,9 classes,22 orders,46 families,69 genera,and the dominant genera were Enterococcus (56.13%) and unclassified Enterobacteriaceae (15.02%);a total of 8 species from 2 phylums,4 families,4 genera of culturable bacteria were isolated,and the dominant phylum,family,genera and species were Firmicutes (62.50%),Bacillaceae (62.50%),Bacillus (62.50%) and Bacillus altitudinis (33.85%),respectively.The ACE index,Chao1 index,Simpson index and Shannon index of the intestinal bacterial community of 3^rd instar larvae of P.gularis population in Baoshan were 852.00,852.00,0.93 and 6.03,respectively,which were higher than the corresponding indexes of the Mangshi population(196.18,196.00,0.91 and 4.73).The results of the differential analysis of KEGG metabolic pathways showed that P.gularis larval intestinal bacteria were mainly involved in metabolic processes such as membrane transport,amino acids and carbohydrates.【Conclusion】The intestinal bacteria of P.gularis larvae are rich in species,with 23 phya,48 classes,121orders,225 families and 408 genera of bacteria,and the diversity of their intestinal bacterial communities varies with the change of geographic conditions,among which,the composition and diversity of intestinal bacterial communities in the Baoshan population is higher than that in the Mangshi population.The intestinal bacteria of P.gularis larvae may be involved in the metabolisms of membrane transport,amino acids and carbohydrates.