Analysis of gut microbial diversity and function in Hyblaea puera (Lepidoptera: Hyblaeidae)

Symbiotic microorganisms play a significant role in the physiology and biochemistry of insects. Hyblaea puera (Lepidoptera: Hyblaeidae), is an emerging invasive pest seriously damaging the mangrove ecosystem (mainly Avicennia marina ) along the coast of China. This study systematically investigated the community structure, diversity and potential functions of the gut bacteria of instar larvae of H. puera under field collection, indoor rearing and starvation treatment. The results revealed that laboratory rearing significantly altered the gut microbial composition. The gut bacteria of laboratory-reared larvae were dominated by the phylum Firmicutes-D, genus Enterococcus and Ligilactobacillus , whereas field-collected larvae exhibited a bacterial community primarily composed of the phyla Bacteroidota and Proteobacteria, genera JC017 and Fulvimarina . Starvation treatment significantly reduced alpha diversity and amplicon sequence variant (ASV) richness of the gut bacteria, and the alpha diversity was significantly lower in laboratory-reared larvae compared to field-collected ones. After starvation, the relative abundance of Enterococcus in laboratory-reared larvae increased markedly to 83.36%, resulting in a mono-dominant microbial structure. In contrast, starved field-collected larvae maintained a more diverse and tolerant community, predominantly consisting of Burkholderia and Acinetobacter . Functional prediction indicated that the gut bacteria was extensively involved in metabolic pathways such as amino acid and vitamin biosynthesis, as well as degradation of aromatic compounds, suggesting its potential role in helping the host overcome mangrove chemical defenses and compensate for nutritional challenges. This study provides a theoretical foundation for understanding the ecological adaptation mechanisms of H. puera and developing microbiome-based strategies for environmentally friendly pest control.