Dynamic changes and functional analysis of gut bacteria in Plutella xylostella under different physiological conditions

BACKGROUND: Insect gut bacterial communities dynamically respond to host physiology and mediate key functions, yet a holistic view of how Plutella xylostella (a devastating cruciferous pest) gut bacteria shift across developmental stages, sexes, and mating statuses remains unclear. This study applied DNA/RNA-based 16S rRNA sequencing to capture high-resolution dynamics of its gut microbiota and decode functional correlations. RESULTS: Phylum-level structure of P. xylostella stayed stable across both sequencing methods (Proteobacteria and Firmicutes as dominants). The top 50 high-abundance bacterial genera annotated by both methods are also consistent, while RNA-based 16S rRNA sequencing reveals that a greater count of high-abundance bacteria exhibited vibrant, physiological state-driven shifts: Eggs thrived with Streptococcus and Enhydrobacter. Larvae boasted the highest diversity (fueled by active feeding, with Ruminococcus, Prevotella may aid cellulose digestion in fed 1st-instars and Massilia, Comamonas may boost breakdown of hard-to-digest food in 4th-instars). Pupae dropped to the lowest diversity (a 'reset' stage, may rely on Enterobacter for energy metabolism). Non-feeding adults had peaking Bifidobacterium and Sphingomonas (may support immune regulation). Feeding adults saw Klebsiella flourish. Sex dimorphism was striking: Males had consistent Delftia enrichment (may enhance pathogen resistance) across stages; females showed stage-specific biases. Mating triggered marked shifts: the abundances of Lactobacillus and Faecalibacterium accumulated in mated females, potentially related to reproduction. CONCLUSION: P. xylostella gut bacteria form a dynamically adaptive community, with taxa may flexibly tune to developmental, sexual, and mating demands, which is of great significance for understanding the association between the gut microbiota and their host. © 2025 Society of Chemical Industry.