AUTHOR=Li Chuanming , Han Guangjie , Sun Jun , Huang Lixin , Lu Yurong , Xia Yang , Liu Qin , Xu Jian 

TITLE=The Gut Microbiota Composition of Cnaphalocrocis medinalis and Their Predicted Contribution to Larval Nutrition

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.909863

DOI=10.3389/fmicb.2022.909863

ISSN=1664-302X

ABSTRACT=<p>Intestinal bacterial flora plays an important role in the nutrition, physiology, and behavior of herbivorous insects. The composition of gut microbiota may also be affected by the food consumed. <italic>Cnaphalocrocis medinalis</italic> is an oligophagous pest, feeds on rice leaves almost exclusively and causes serious damage to rice in Asian countries. Using antibiotic treatment and metagenome sequencing, we investigated the influence of the food sources (rice and maize seedlings) on the structure and functions of intestinal bacteria of <italic>C. medinalis</italic>. Firstly, food utilization indices, relative growth rate (<italic>RGR</italic>), relative consumption rate (<italic>RCR</italic>), efficiency of conversion of ingested food (<italic>ECI</italic>), and efficiency of conversion of digested food (<italic>ECD</italic>), were all significantly adversely affected in the antibiotic treatment eliminating gut bacteria, showing that the microbiota loading in the gut were essential for the larva growth and development of <italic>C. medinalis</italic>. Further, metagenome sequencing revealed that different diets caused a variation in gut microbiota composition of <italic>C. medinalis</italic>, indicating that the gut microbiota were in part driven by the diet provided. However, the larvae of <italic>C. medinalis</italic> hosted a core microbial community in the gut, which was independent from the diets changing. The dominant bacteria in the two feeding groups were highly consistent in the gut of <italic>C. medinalis</italic> larvae, with the gut bacterial community dominated by Firmicutes at the phylum level, <italic>Enterococcus</italic> at the genus level, <italic>Enterococcus</italic> sp. FDAARGOS-375, <italic>E. casseliflavus</italic>, <italic>E. gallinarum</italic>, and <italic>E.</italic> sp. CR-Ec1 accounted for more than 96% of the gut microbiota. Functional prediction analysis demonstrated that gut bacteria encoded a series of metabolism-related enzymes involved in carbohydrate metabolism and amino acid synthesis. Carbohydrate metabolism was the most enriched function in both groups and was more abundant in rice feeding group than in maize feeding group. The core dominant <italic>Enterococcus</italic> species possessed complete pathways of 14 carbohydrates metabolism, 11 amino acids biosynthesis, and two vitamins synthesize, implied to contribute an essential role to the nutrition intake and development of <italic>C. medinalis</italic>. Finally, the study may provide an in-depth analysis of the symbiont-host co-adaptation and new insights into the management of <italic>C. medinalis</italic>.</p>