Host genetics and environment shape the gut microbiome of Euschistus heros and Piezodorus guildinii and potentially influencing their adaptation

Background Euschistus heros and Piezodorus guildinii are major soybean pests across the Americas. Gut-associated bacteria influence insect nutrition, detoxification, and stress tolerance, potentially enhancing adaptation to diverse hosts and management regimes. We investigated how host genetics and environment shape gut microbiome structure and functional potential in these species. Results We sequenced the 16S rRNA V4 region from 189 insects collected across Brazil and the United States. Microbiomes were dominated by Proteobacteria and Firmicutes, exhibiting high intra- and interpopulation variability. Diversity and community structure varied significantly among lineages and locations; while environment explained a larger share of overall variance, host genetics provided a more distinct statistical signal for group differentiation. In E. heros , genera linked to nutrient acquisition and detoxification (e.g., Pantoea , Wolbachia ) were more prevalent. In P. guildinii , Candidatus Benitsuchiphilus —associated with diapause and uric-acid metabolism—predominated. Predicted functions included chemoheterotrophy, nitrogen fixation, and degradation of aromatic compounds, with distinct patterns across species and geographic lineages. Conclusion Both genetic and environmental factors shape the composition and functional capacity of stink bug gut microbiomes, potentially contributing to host adaptation across different agricultural landscapes. These insights open avenues for microbiome-informed strategies to improve the sustainability and efficacy of soybean pest management.