A new analysis of thousands of native and nonnative Michigan bees shows that the most diverse bee communities have the lowest levels of three common viral pathogens.
University of Michigan researchers netted and trapped more than 4,000 bees from 60 species. The bees were collected at winter squash farms across Michigan, where both managed honeybee colonies and wild native bees pollinate the squash flowers.
All but one species — Apis mellifera, the common European honeybee — are native bees. The number of bee species found at each farm ranged from seven to 49.
Consistently, lower virus levels were strongly linked to greater species richness among the local bee communities. The study was published online Feb. 11 in the journal Ecology.
“This result is exciting because it suggests that promoting diverse bee communities may be a win-win strategy to simultaneously reduce viral infections in managed honeybee colonies while helping to maintain native bee biodiversity,” said study lead author Michelle Fearon, a postdoctoral researcher in the University of Michigan Department of Ecology and Evolutionary Biology.
“In light of recent global pollinator population declines that are due in part to the spread of pathogens, these results offer hope that conservation efforts could also broadly benefit pollinator health,” said Fearon, who conducted the study for her doctoral dissertation. She is now pursuing a follow-up study that explores how natural areas keep pollinator communities healthy.
The Ecology study is the first to show that high levels of biodiversity within bee communities can help dilute the harmful effects of viral pathogens. Support for this “dilution effect” has been reported in other host—pathogen systems — such as tick-borne Lyme disease — but this is the first time it’s been seen with pollinator viruses. The idea of a dilution effect remains controversial among ecologists, however.
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