Controlling Varroa destructor infestations in managed honeybee colonies limits virus spillover into wild pollinator communities

Abstract

Given recent pathogen-mediated pollinator declines, there is concern regarding virus spillover from managed honeybees to wild pollinators. While the parasitic mite Varroa destructor specializes on honeybees, the viruses it transmits are widespread throughout pollinator communities. Here, we investigated whether beekeeper control of varroa mites influences the magnitude of deformed wing virus (DWV) spillover into wild pollinators. We sampled 27 apiaries along a gradient of mite infestation, screening nearly 1000 pollinators and 350 flowers for DWV via quantitative PCR. We found that controlling varroa below the recommended treatment threshold reduced DWV loads in honeybees by over 100-fold. When varroa was controlled, DWV prevalence was reduced by over 35% on flowers and by 39%-85% in wild pollinators surrounding apiaries. These results demonstrate that sustainable beekeeping practices can limit viral spillover through the control of varroa mites, thereby safeguarding the health of both managed and wild pollinators alike.