# Symbiotic Diversity of Sap-Feeding Auchenorrhyncha (Hemiptera) in the Upland Landscapes of Central Cardamom Mountains, Cambodia

## TL;DR

This study explores the bacterial symbionts in sap-feeding insects from Cambodia's Cardamom Mountains, finding that host species strongly influence microbial diversity.

## Contribution

The study reveals host-specific patterns of bacterial symbiont diversity in Auchenorrhyncha insects from tropical montane ecosystems.

## Key findings

- Candidatus Karelsulcia muelleri was the dominant obligate symbiont across all host species.
- Symbiont diversity varied significantly among host species, with some harboring multiple co-obligate and secondary symbionts.
- Host species explained 87% of the variation in symbiont composition, with minimal influence from environmental factors.

## Abstract

Auchenorrhyncha (Hemiptera) harbor diverse bacterial symbionts that play critical roles in host nutrition, adaptation and vector competence. However, how symbiotic communities vary across host species and ecological gradients in tropical montane ecosystems remains poorly understood. Here, we characterized the bacterial microbiota of eight auchenorrhynchan species collected from the upland landscapes of the Central Cardamom mountains, Cambodia, using 16S rRNA (V3-V4) amplicon sequencing. In total, 83 individuals representing eight species were analyzed. Across 188 amplicon sequence variants (ASVs), the obligate symbiont Candidatus (Ca.) Karelsulcia muelleri dominated all hosts, although its relative abundance varied substantially. While some species (Anagonalia sp., Changwhania sp. and Mukaria sp.) contained nearly exclusively Karelsulcia, others harbored diverse co-obligate (Ca. Zinderia) and secondary symbionts, including Rickettsia, Wolbachia, Arsenophonus, Spiroplasma, Ca. Symbiodolus, Ca. Lariskella, Pectobacterium and Xylella. Symbiont composition was highly host-specific, with Clovia sp. exhibiting the greatest diversity and Hecalus sp. dominated by Rickettsia. β-diversity analysis confirmed that host species explained most variation (87%), whereas topographic variables (exposure level and mountain locality) contributed little, although Ca. Symbiodolus in Stirellus sp2. was more frequent at high-exposure sites. Cross-correlation analysis revealed that only a restricted subset of bacterial taxa correlated significantly with plants families, suggesting selective ecological filtering. Notably, Spiroplasma was positively associated with sundew plants (Droseraceae), whereas Pectobacterium showed consistent negative correlations with multiple plant families. Overall, these findings demonstrate that microbiota in Auchenorrhyncha are shaped primarily by host species, with minor influences from environment and plant associations, highlighting the ecological and evolutionary drivers of symbiotic diversity in sap-feeding insects inhabiting tropical mountain landscapes.

The online version contains supplementary material available at 10.1007/s00248-026-02724-3.