Metagenomic Analysis of Gut Microbiome Across Developmental Stage of Asian Corn Borer (Ostrinia furnacalis)

Ostrinia furnacalis is one of the most important agricultural pests in Asia. Previous studies utilizing 16S rRNA sequencing have established a foundational understanding of the taxonomic composition of its gut microbiota; however, the dynamic functional transitions across the host’s entire life cycle remain poorly understood. In this study, we used metagenomic sequencing to systematically characterize the gut microbiome across six groups representing different life stages and sexes of O. furnacalis: first-instar, third-instar, and fifth-instar larvae, pupae, and adults (both males and females). Microbial richness and evenness vary significantly across six groups representing different life stages and sexes. Species richness is highest in the first-instar larvae (L1D2), while evenness is relatively high in both first- and third-instar larvae (L1D2 and L3D2). Additionally, no sex-based differences were observed in either indicator during the adult stage. Enterococcus mundtii is the primary species driving community succession and rapidly achieves dominance after the third-instar stage. Co-occurrence network analysis revealed that the first-instar larval network exhibits the highest complexity, with positive correlations accounting for 96.6% of all edges. Conversely, the fifth-instar larvae exhibits the greatest proportion of negative correlation edges at 29.13%, while the pupal stage network is the most dispersive, indicating microbial reorganization during metamorphosis. Functional annotation reveals that carbohydrate and amino acid metabolism pathways are significantly enriched during the larval stage. In contrast, the pupal stage is characterized by enrichment in environmental information processing and a notable increase in polysaccharide lyases (PLs). This shift indicates that the microbiota transitioned from degrading plant polysaccharides to foraging host-derived glycans. The number of resistance genes in the first-instar larvae is significantly higher than that in all other groups representing different life stages and sexes. Collectively, this study systematically reveals the dynamic succession patterns of the gut microbiome throughout the life cycle of O. furnacalis and provides a theoretical foundation for the development of microbiome-based pest management strategies.