Arabidopsis phyllosphere microbiota during Pieris brassicae herbivory under gnotobiotic conditions

Plant leaves host diverse bacterial communities that can influence plant–insect interactions. We used a gnotobiotic Arabidopsis–Pieris brassicae system inoculated with defined synthetic phyllosphere bacterial communities (SynComs) to examine how herbivory reshapes leaf-associated microbiota and drives bacterial transmission to insect larvae. 16S rRNA gene profiling showed that feeding shifted community composition, with Pantoea eucalypti 299R and related taxa becoming dominant. Larvae acquired only a subset of leaf bacteria, mainly Methylobacterium, Microbacterium, Williamsia, and Curtobacterium, indicating strong filtering during gut passage. These data highlight how herbivory restructures phyllosphere microbiota and shapes bacterial transmission across plant–insect interfaces.