Abstract:

Objective: This study aims to investigate the diversity of the gut bacterial composition of the larvae of Dioryctria sylvestrella, to analyze the potential functions of the gut bacteria, and to obtain the culturable bacteria by using the traditional isolation and cultivation methods, so as to store up bacterial resources for the future verification of the functions of gut bacteria, and to provide a new idea and scientific basis for the development of the prevention and control strategy of this pest. Method: Macro-genomics technology was used in combination with traditional isolation and culture methods to analyze the gut bacteria in larvae of D. sylvestrella, which feeds on Pinus sylvestris var. mongolica, from both macroscopic and microscopic perspectives. Result: Through macro-genome sequencing analysis, a total of 70 phyla and 59 classes (some not yet been annotated to classes), 129 orders, 266 families, 493 genera and 1 050 species of bacteria were clearly annotated. At the level of phylum classification, Proteobacteria accounted for 67.8%, which was the dominant phylum; at the level of genus, Wolbachia, Piscirickettsia and Enterobacter accounted for 15.91%, 14.55%, and 12.68%, respectively, which all were dominant genera. In the analysis of the potential functions of the gut bacteria in the larvae of the D. sylvestrella, the metabolic pathway accounted for the largest proportion of abundance, mainly performing energy metabolism, sugar metabolism and so on. A total of 15 bacterial strains were isolated and identified from the larval gut of D. sylvestrella using the traditional bacterial isolation and purification culture method, and they belonged to 3 phyla, 4 classes, 6 orders, 7 families, 11 genera and 15 species, including Pseudomonas soli, Pseudomonas entomophila, Enterobacter ludwigii, Erwinia sp., Klebsiella oxytoca, Leclercia adecarboxylata, Pantoea rodasi, Klebsiella_aerogenes, Erwinia_billingiae, Enterobacter cloacae, Stenotrophomonas maltophilia, and Ralstonia insidios. Conclusion: The dominant phylum is Proteobacteria and the dominant genus is Enterobacteriaceae. The results show that the gut bacterial flora of the larvae of D. sylvestrella is rich, which reveals the potential role of microorganisms in the growth and development, nutrient metabolism, and ecological adaptation of D. sylvestrella, and can provide an important scientific basis for the research and development of new pest biological control technologies.

Key words: Dioryctria sylvestrella, bacteria, diversity, macrogenome