Exoskeletal microbiomes of introduced dung beetles

Introduced dung beetles face numerous challenges when establishing in new environments; one of them being infection by entomopathogenic microorganisms. The microbes associated with insect hosts, collectively termed 'the microbiome', have been shown to be important in susceptibility to entomopathogen infection.
In this study, we used a targeted phylogenetic marker gene sequencing approach to investigate the composition of the exoskeletal microbiome of introduced dung beetles in controlled-environment rearing conditions. Swabs from the exoskeletons of 'alive and healthy' dung beetles, and 'diseased and dead' dung beetles of various species were cultured on selective media to isolate the microorganisms. The fungal and bacterial operational taxonomic units were identified by Illumina MiSeq next-generation sequencing, targeting ITS and 16SrRNA genes in genomic DNA extracted from culture plates.
The diversity of fungi and bacteria associated with the exoskeleton of introduced dung beetles differed among the dung beetle species. There was a significant reduction in the microbial diversity among 'diseased and dead' beetles in contrast to 'alive and healthy' beetles. Entomopathogenic fungi associated with exoskeletal microbiomes were more prevalent in 'diseased and dead' beetles. Further investigation into ‘healthy’ and ‘diseased’ microbiomes of dung beetles is warranted to establish the relationship between dung beetle health and their exoskeletal microbiome.