Pathogen shifts in a honeybee predator following the arrival of the Varroa mite

Emerging infectious diseases (EIDs) are a global threat to honeybees, and spillover from managed bees threaten wider insect populations. Deformed wing virus (DWV), a widespread virus that has become emergent in conjunction with the spread of the miteVarroa destructor , is thought to be partly responsible for global colony losses. The arrival ofVarroa in honeybee populations causes a dramatic loss of viral genotypic diversity, favouring a few virulent strains. Here, we investigate DWV spillover in an invasive Hawaiian population of the wasp,Vespula pensylvanica , a honeybee predator and honey-raider. We show thatVespula underwent a parallel loss in DWV variant diversity upon the arrival ofVarroa , despite the mite being a honeybee specialist. The observed shift inVespula DWV and the variant-sharing betweenVespula andApis suggest that these wasps can acquire DWV directly or indirectly from honeybees.Apis prey items collected fromVespula foragers were positive for DWV, indicating predation is a possible route of transmission. We also sought cascading effects of DWV shifts in a broaderVespula pathogen community. We identified concurrent changes in a suite of additional pathogens, as well as shifts in the associations between these pathogens inVespula . These findings reveal how hidden effects of theVarroa mite can, via spillover, transform the composition of pathogens in interacting species, with potential knock-on effects for entire pathogen communities.