Viral and fungal pathogens associated with Pneumolaelaps niutirani (Acari: Laelapidae): a mite found in diseased nests of Vespula wasps

Introduced social wasps (Vespula spp.) are a pest in many parts of the world. Recently, a mite species (Pneumolaelaps niutirani) was described and associated with disease symptoms in wasps. The mite does not appear to directly parasitise the wasps, but has been observed in high abundance, feeding on exudates from the mouths of larvae. We investigated the viral and fungal pathogens community in these mites and wasps. We found known viruses including Moku virus in both wasps and mites. Moku virus replicated in mites, likely indicating parasitism. Deformed wing virus, commonly found in wasps, was also detected in mite samples. Furthermore, the presence of putative viral transcripts related to 38 distinct viruses, including seven viruses previously isolated from arthropods, indicated that there may be many more viruses associated with the mite that are potentially shared with Vespula wasps. We also found generalist entomopathogenic fungus Aspergillus to infect both mites and wasps. Twelve distinct Aspergillus species were observed, all of which were found in wasp larvae from nests displaying symptoms of disease, with only one species in larvae from apparently healthy nests. Aspergillus novofumigatus was the most common of these species observed in wasps. Six Aspergillus species, including A. novofumigatus were detected in mites. Aspergillus loads were significantly higher in larvae from diseased nests. Our exploratory study indicates that mites can harbour both viruses and fungi that infect wasps, providing avenues of research into biological control using mites as infection vectors.