DISCUSSION
In this study we investigated changes in the bumble bee virome under
field conditions in relation to habitat composition and configuration.
Our results show that viral loads and viral richness increased after
field exposure and shifted from an initial dominance of honey bee
associated viruses to a higher virus richness in the colonies at the end
of the experiment, including several different bumble bee viruses. The
spatial structure of the surrounding landscape was related to the
changes in viral patterns at fine spatial scales, with habitat Shannon
diversity being positively linked to lower virus richness and appearance
of new viruses, while well-connected agricultural patches decreased the
viral load. Colony development parameters were not directly negatively
affected by viruses but were influenced by the same landscape parameters
that drove virus prevalence. Our results emphasize the importance of
landscape heterogeneity and connectivity for wild pollinator health .