Environmental Contamination Affects Associated Bacterial Communities in a Neotropical Arboreal Ant

Abstract

Environmental stressors such as contamination from mining tailings can alter microbial communities associated with insects, including social ants. Ants, as widespread and ecologically influential insects with stable microbial associations, offer a relevant model to examine these effects. We investigate whether exposure to iron-rich tailings from a mining disaster is linked to changes in the diversity and composition of cuticle-associated bacterial communities in the arboreal ant Azteca chartifex. Using 16S rRNA gene amplicon sequencing, we compared ants from contaminated and protected areas in the Atlantic Forest. We tested whether bacterial diversity and community composition differ between environments and whether contamination is associated with changes in the ants' population-level core microbiota and the occurrence of indicator taxa. Ants from the contaminated area exhibited higher alpha diversity and a more variable microbiota across populations, while those from the protected area showed more similar microbiota. Community composition differed significantly between protected and contaminated environments, and distinct bioindicator bacteria were associated with each site. While our design was constrained by temporal and spatial separation between sites, the consistent core bacterial community across protected populations suggests that contamination, rather than distance, primarily explains the observed patterns. These results indicate that environmental contamination may influence ants' bacterial communities, potentially reflecting a response to ecological stress and altering microbe–host–environment interactions. This study provides a first assessment of how exposure to mining tailings may shape the microbiota associated with a dominant arboreal ant species and contributes to our understanding of insect–microbe dynamics in disturbed tropical ecosystems.