Genome-resolved metagenomics reveals conserved, flexible and emerging symbioses across global leafhoppers

BackgroundLeafhoppers are among the most important insect vectors of plant pathogens worldwide and depend on microbial symbionts to exploit nutrient-poor phloem diets. However, most studies of leafhopper-associated microbiota have focused on a limited number of taxa or marker-gene surveys, leaving the genomic diversity, ecological organization, and functional potential of these microbial communities poorly understood. Here, we generated the Global Leafhopper Microbiome Catalog by integrating genome-resolved metagenomics from 171 leafhopper species across 11 subfamilies and 13 countries, including the first microbiomes characterized from Arctic leafhoppers. ResultsDe novo assembly and genome reconstruction generated 337 high-quality non-redundant microbial genomes and 18.6 million non-redundant genes, substantially expanding the known microbial diversity associated with Cicadellidae, including several previously undescribed bacterial lineages. Comparative analyses revealed a recurrent modular microbiome architecture composed of: (i) a conserved core of obligate nutritional symbionts, dominated by Candidatus Karelsulcia and Candidatus Nasuia; (ii) a heterogeneous layer of secondary symbionts, including Wolbachia, Arsenophonus, Rickettsia, and Diplorickettsia; and (iii) a dynamic pool of environmentally acquired bacteria. While obligate symbionts remained highly conserved across divergent hosts, secondary and environmental taxa varied substantially among species and regions, suggesting repeated acquisition shaped by ecological filtering rather than host phylogeny alone. Comparative analyses between the specialist corn leafhopper Dalbulus maidis and the more polyphagous aster leafhopper Macrosteles quadrilineatus further showed that closely related vectors can maintain conserved ancestral symbionts while harboring markedly distinct accessory microbiomes. Arctic populations contained unique microbial assemblages enriched in functions associated with cold tolerance, oxidative stress, and reproductive manipulation. In addition, we identified numerous plant-associated bacteria, including phytoplasmas, spiroplasmas, Pantoea, and Erwinia, alongside taxa with predicted nutritional and plant growth-promoting functions. ConclusionsOur findings reveal that leafhopper microbiomes are structured through the interaction of ancient obligate symbioses and flexible environmentally responsive microbial layers. This work establishes a genome-resolved framework for understanding microbiome evolution in insect vectors and highlights the potential role of microbial community structure in host adaptation, pathogen ecology, and sustainable pest management.