Habitat prevails over host sex in influencing mycobiome structure of terrestrial isopod, <i>Armadillidium vulgare</i>

The terrestrial isopod, a crustacean order that has successfully transitioned from aquatic to land ecosystem, functions as a soil bioengineer and plays a crucial role in ecological decomposition. While there has been comprehensive documentation of bacterial associations with isopods, suggesting their contribution to digestive processes, the fungal component of isopods remains a less-explored dimension. Expanding our fundamental exploration into terrestrial isopods, we investigated whether the fungal community in <i>Armadillidium vulgare</i> is more significantly influenced by host sex or habitat using high-throughput sequencing-based internal transcribed spacer region amplification. Our findings revealed that the isopod mycobiome structure and taxonomic composition are predominantly shaped by the host's habitat rather than its sex. While the fungal richness of the mycobiome varied based on isopod sex, the co-occurrence network exhibited distinct variations dependent on both habitat and host sex. Finally, we observed a complete overlap of core mycobiomes based on isopod sex and identified fungal residents that are consistently distributed in a manner specific to habitat. In conclusion, we assert that community assembly of the isopod mycobiome in an untouched ecosystem is more significantly influenced by location than sex. We contend that this offers a fundamental groundwork, laying the cornerstone for future investigations into terrestrial isopods-pivotal agents in ecological decomposition within ecosystems.IMPORTANCEThis study addresses a significant knowledge gap in the mycobiome of terrestrial isopods, an area that has received limited scientific attention despite extensive research on bacterial associations within these organisms. Using high-throughput sequencing, this study demonstrates that the habitat of <i>Armadillidium vulgare</i> exerts a more pronounced influence on the composition of its mycobiome compared with host sex. By examining variations in community structure, diversity, co-occurrence patterns, and identifying core mycobiomes and specialist taxa based on isopod location, this study provides crucial foundational data. These findings are essential for advancing future research on the ecological and evolutionary dynamics of fungal communities in terrestrial isopods.