- Author: Kathy Keatley Garvey
The news is disturbing but not unexpected.
Scientists are linking global climate change to one reason why the worldwide population of bumble bees is declining.
An article published Sept. 28 in the journal Ecology Letters by Florida State University (FSU) researchers showed that bumble bees just aren't getting enough floral resources.
For the study, lead researcher and postdoctoral fellow Jane Ogilivie and six colleagues examined three subalpine bumble bee species in Colorado's Rocky Mountains, and found that the changing climate means fewer flowers.
"Knowing whether climate variation most affects bumble bees directly or indirectly will allow us to better predict how bumble bee populations will cope with continued climate change," Ogilivie told the FSU News Service in a press release. "We found that the abundances of all three bumble bee species were mostly affected by indirect effects of climate on flower distribution through a season."
The FSU News Service aptly headlined the research a "Stinging Report."
"When researchers think about flower effects on bees, they typically consider floral abundance to be the most important factor, but we found that the distribution of flowers throughout a season was most important for bumble bees,” Ogilivie said. “The more days with good flower availability, the more bees can forage and colonies can grow, and the bigger their populations become. We now have longer flowering seasons because of earlier snowmelt, but floral abundance has not changed overall. This means we have more days in a season with poor flower availability.”
The researchers wrote in their abstract: "Climate change can influence consumer populations both directly, by affecting survival and reproduction, and indirectly, by altering resources. However, little is known about the relative importance of direct and indirect effects, particularly for species important to ecosystem functioning, like pollinators. We used structural equation modelling to test the importance of direct and indirect (via floral resources) climate effects on the interannual abundance of three subalpine bumble bee species. In addition, we used long-term data to examine how climate and floral resources have changed over time. Over 8 years, bee abundances were driven primarily by the indirect effects of climate on the temporal distribution of floral resources. Over 43 years, aspects of floral phenology changed in ways that indicate species-specific effects on bees. Our study suggests that climate-driven alterations in floral resource phenology can play a critical role in governing bee population responses to global change."
Bumble bee expert Robbin Thorp, distinguished emeritus professor of entomology at the University of California, Davis, long ago sounded the alarm that bumble bees are in trouble. He is the co-author of Bumble Bees of North America: an Identification Guide (Princeton) and California Bees and Blooms: A Guide for Gardeners and Naturalists.
The last bumble bee we saw--the last of the season--was on Sept. 23 at Kate Frey's pollinator garden at the Sonoma Cornerstone, Sonoma. It was a yellow-faced queen bumble bee, Bombus vosnesenskii, nectaring on a spiked floral purple plant, Salvia ‘Indigo Spires' (Salvia farinacea x S. farinacea). The queen had apparently emerged from hibernation to find food on that warm summerlike day.
I knelt to capture some images.
"Oh, it's just a bumble bee," scoffed one tourist, casually sipping a glass of wine. "They're everywhere."
Sadly, they're not.
- Author: Kathy Keatley Garvey
You can tell it's almost spring when you hear bees buzzing on the flowering crab apples.
Spring officially starts Friday, March 20, but don't tell that to the bees.
They're in the midst of their spring build-up.
Meanwhile, California Agriculture Day beckons.
The California State Beekeepers' Association and other ag-affiiiated organzations are gearing up for the annual California Ag Day, part of National Agriculture Week.
California Ag Day, free and open to the public, takes place from 11:30 a.m. to 1 p.m., Wednesday, March 18 on the west steps of the state capitol.
There you'll see a John Deere tractor parked on the steps, 4-H'ers and FFA'ers showing their animals, and ag industries displaying educational material and offering samples. Generally, it's a day to celebrate agriculture and thank the farmers and growers for the bounty that we tend to take for granted. This year's theme is “California Agriculture: Breaking new Ground." The focus: the importance of soil health to our food supply and all of agriculture.
Said Secretary of Agriculture Karen Ross: "National Agriculture Week gives us the opportunity to celebrate agriculture, an industry that provides a safe, abundant, and affordable food supply, a strong economy, and a world of job opportunities.”
If you stop by the California State Beekeepers' Association booth on California Ag Day, you can learn first-hand about bees from the beekeepers and "honey bee guru" Extension apiculturist (emeritus) Eric Mussen of the UC Davis Department of Entomology and Nematology, who retired last June after 38 years of service.
Generally, they're asked:
- How are the bees doing?"
- "What can we do to help?"
- "How difficult is it to keep bees?"
- "How can I learn beekeeping?"
- "What's wrong with my bees?"
There's a reward, too, for visiting the booth. You'll receive a sweet treat: a honey stick.
Did you know that it takes honey bees 10 million floral visits to make a pound of honey? (Source: Bees of the World by Christopher O'Toole and Anthony Raw). "The members of a single hive may make four and a half million visits to flowers in the course of one day's work and more than one thousand workers will die every day in the summer," they write. "Cause of death? Sheer exhaustion. Life expectancy? Af the height of the nectar-gathering season, a mere six weeks."
That's something to think about the next time you see the foragers going about their bees-ness.