Nav: Home

The buzz about bumble bees isn't good

April 23, 2019

EAST LANSING, Mich. - While many scientists are focused on the decline of honey bees, relatively few study bumble bees. The good news is that a new study provides an estimate on bumble bee population and distributions across Michigan in the past century. The bad news is that these results are dramatically low, and they mirror what's happening across the Americas, Europe and Asia, too.

Michigan State University led the study, which compared current distributions of bumble bee species across the state to the information gleaned from museum specimens collected as far back as the 1880s. The research, published in the current issue of Ecology, shows that half of the bumble bee species studied have declined by more than 50%.

"Bumble bees are important pollinators of plants across natural habitats, where they help support the seeds and berries that birds and other animals depend on," said Thomas Wood, MSU entomology postdoctoral researcher and lead author of the study. "They also are effective pollinators of many fruits and vegetables that are important for healthy human diets."

Take blueberries, for example. Bumble bees are highly efficient pollinators of this leading Michigan fruit crop. To extract the pollen necessary for fertilization, the blossom needs to be shaken vigorously, and bumble bees are expert at vibrating the flowers to shake out the pollen.

"In Michigan, there are 19 species of bumble bees and around 445 species of other bees," said Wood, who led the study in the lab of Rufus Isaacs, MSU entomologist. "Many of Michigan's key crops depend on them. In fact, about 50 percent of cherry pollination is carried out by wild bees."

Wood's team scoured the state of Michigan and compared the distribution of 12 different bumble bee species across the state's 83 counties before and after the year 2000. Some of the biggest declines include:
  • Rusty patched bumble bee - 100%
  • American bumble bee - 98%
  • Yellow banded bumble bee - 71%
  • Yellow bumble bee - 65%
Even though the study focused on Michigan, its findings hold lessons for other regions around the globe, and some of them are positive. A couple of success stories include the common eastern bumble bee and the brown belted bumble bee, which increased by 31% and 10%, respectively.

Why did some species remain stable or increase their ranges while other species declined?

Researchers investigated the kinds of plants each bumble bee species visited by removing pollen from the specimens. Bumble bees carry their pollen on their back legs, and this can be removed and identified under a microscope, even decades after the bee was alive. When looking at these pollen loads, the researchers found some consistent patterns.

"Species that declined collected pollen from fewer species of plants and seem to have a narrower range of plants they visit for pollen," Wood said. "In contrast, the stable species visit a much wider variety of plants. This suggests that picky eaters are less able to switch if a favorite plant isn't available."

The next phase of the research will try to understand why bumble bee species with narrow diets do not show diet flexibility.

"Most of the declining bumble bee species in Michigan fly in the summer, feeding on prairie plants and other flowers of open countryside," Wood said. "Fewer types of plants flower in summer compared to the spring. We also know that prairies have been lost over the last century so summer bumble bees may have been hit twice due to a loss of their preferred habitat and a reduced ability to adapt to this change."
-end-
Kelsey Graham, MSU entomologist, and Jason Gibbs, University of Manitoba, also contributed to this study.

This research was funded in part by the USDA National Institute for Food and Agriculture, through the Great Lakes Great Bees project.

(Note for media: Please include a link to the original paper in online coverage: https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecy.2697.)

Michigan State University has been working to advance the common good in uncommon ways for 160 years. One of the top research universities in the world, MSU focuses its vast resources on creating solutions to some of the world's most pressing challenges, while providing life-changing opportunities to a diverse and inclusive academic community through more than 200 programs of study in 17 degree-granting colleges.

For MSU news on the Web, go to MSUToday. Follow MSU News on Twitter at twitter.com/MSUnews.

Michigan State University

Related Bees Articles:

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.
Where are the bees? Tracking down which flowers they pollinate
Earlham Institute (EI), with the University of East Anglia (UEA), have developed a new method to rapidly identify the sources of bee pollen to understand which flowers are important for bees.
Pesticides deliver a one-two punch to honey bees
A new paper in Environmental Toxicology and Chemistry reveals that adjuvants, chemicals commonly added to pesticides, amplify toxicity affecting mortality rates, flight intensity, colony intensity, and pupae development in honey bees.
Bees can count with just four nerve cells in their brains
Bees can solve seemingly clever counting tasks with very small numbers of nerve cells in their brains, according to researchers at Queen Mary University of London.
Trees for bees
Planting more hedgerows and trees could hold the key to helping UK bees thrive once again, a new study argues.
More Bees News and Bees Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...