Viral pathogens that might play a role in the decline in wild bumblebees may be transmitted from managed honeybees through flowers, according to a study published June 26 in the open-access journal PLOS ONE by Samantha Alger of the University of Vermont, and colleagues.
The decline of many bumblebee species has been linked to an increased prevalence of pathogens caused by spillover from managed bees. RNA viruses, which may be contributing to the observed declines in bumblebees, are suspected of moving from managed honeybees into wild bumblebees through shared floral resources. However, the degree to which viruses can be horizontally transmitted, with flowers acting as a bridge, remains poorly understood. To address this gap in knowledge, Alger and her colleagues examined if RNA viruses spill over from managed honeybees, the extent to which viruses are replicating within bumblebees, and the role of flowers in transmission.
The authors found that the prevalence of two RNA viruses -- the deformed wing virus (DWV) and the black queen cell virus (BQCV) -- was higher in bumblebees collected near apiaries, where beehives are kept. Active infections with DWV were also higher in bumblebees collected near apiaries, whereas no DWV was found in bumblebees where honeybee foragers and honeybee apiaries were absent. Moreover, the researchers detected viruses on 19% of flowers, only from sites within apiaries. Taken together, the results support the hypothesis that viruses are spilling over from managed honeybees to wild bumblebees, and that flowers may be an important route for transmission. According to the authors, the findings could guide efforts to protect vulnerable bumblebee species.
Alger adds: "The study supports a widely accepted yet largely untested hypothesis: viruses are spilling over from managed honey bees into wild bumble bee species and this is likely occurring through the shared use of flowers."
Citation: Alger SA, Burnham PA, Boncristiani HF, Brody AK (2019) RNA virus spillover from managed honeybees (Apis mellifera) to wild bumblebees (Bombus spp.). PLoS ONE 14(6): e0217822. https:/
Funding: Funding was provided by a National Science Foundation Graduate Research Fellowship to SAA (DGE-1451866) (https:/
Competing Interests: The authors have declared that no competing interests exist.
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