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Issues Of The Environment: UM Study Shows Our Roads Threaten Bee Movement And Pollination

Gordon Fitch

Over many years, there has been a precipitous decline in our bee populations and that has a significant and negative impact on agriculture and the health of our ecosystem. Bees are one of our great pollinators, and human habitat is a major problem. University of Michigan doctoral candidate Gordon Fitch shares with WEMU's David Fair a novel approach he co-designed to monitor bees within the urban landscape.


  • Road networks extend some 20 million miles across the globe, and that number is projected to increase by an additional 15 million miles or so by 2050.

  • It is well-established that roads disrupt the movement of animals, and large highways kill billions of insects each year. Less is understood about how roads change the movement of pollinators, like bees, or how this affects the plants they pollinate.

  • U-M doctoral candidates Gordon Fitch and Chatura Vaidya designed a novel approach to monitoring the movements of bees within the urban landscape at 47 sites in Ann Arbor. Their study found that roads have a significant impact on bees, threatening their movements and pollination abilities. 

  • To encourage local bees don’t use pesticides, plant a variety of flowering plants to furnish blooms all season long, and delay mowing and yard work where possible to allow bees more areas to forage, over-winter, and nest underground.

  • “Ours is the first well-replicated study to examine how roads impact bee movement,” Fitch said. “Moreover, we used an innovative technique relying on pigment as a pollen analog — rather than direct observation of insect behavior — which allowed us to collect data efficiently. As such, we are also the first to show that roads disrupt the movement of pollen between plants.”

U-M study: Roads threaten bee movement, flower pollination

The full paper: "Roads pose a significant barrier to bee movement, mediated by road size, traffic and bee identity" is free for a limited time in Journal of Applied Ecology.

(Source: *directly quoted*https://appliedecologistsblog.com/2021/05/13/do-roads-pose-a-significant-barrier-to-bee-movement/)

Gordon Fitch answers: How can we encourage our local bee populations?

To your question about imperiled bees: To be perfectly honest, we don't have a great sense for population trends locally. More generally, many species of bumble bees and some other bees that nest underground are not doing well. As to how people can encourage them, the big three are:

  1. Don't use synthetic pesticides, herbicides, or fungicides on their plants and landscapes. This means also checking the source of plants from nurseries as well as mulch, since these are often treated with chemicals before consumers buy them.
  2. Plant a diversity of flowering plants, ideally so that you have plants in bloom during the entire growing season.
  3. Ease up on yard maintenance: plants, like clover in less-frequently mowed lawns, are great bee food; bees often nest in the stems of last years' plants, so if you leave them in the ground for a few weeks after spring warm up; bees will be able to emerge first; leaving patches of bare ground (rather than a thick layer of mulch) provides nesting habitat for bees that nest underground.

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— David Fair is the WEMU News Director and host of Morning Edition on WEMU.  You can contact David at734.487.3363, on twitter @DavidFairWEMU, or email him at dfair@emich.edu

Contact David: dfair@emich.edu
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