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.
Nice to see you!
That's how we greeted our very last bumble bee of 2016.
The yellow-faced bumble bee, Bombus vosnesenskii, apparently came out of hibernation and started nectaring on mallow Nov. 14 at the Natural Bridges State Park, Santa Cruz. We were at the park to see the overwintering monarch butterflies, but it was definitely delightful to see another insect species as well.
Ms. Bombus buzzed from one mallow to the other, keeping her distance from the two-legged park visitors. Once she nearly collided with an overwintering monarch heading for tropical milkweed blossoms.
B. vosnesenskii, native to the west coast of North America and found from British Columbia to Baja California, is an iconic pollinator and also an important pollinator for such crops as greenhouse tomatoes. It's among the bumble bees featured in the book, Bumble Bees of North America: An Identification Guide (Princeton University), the award-winning work of Paul H. Williams, Robbin W. Thorp, Leif L. Richardson and Sheila R. Colla.
When you click on the Princeton site, you'll hear the familiar buzz of bumble bees. It's just like encountering them in a wildflower meadow and listening to them take flight. It's a sound, unfortunately, that we're not hearing that much any more. The world's bumble bee population is declining, and some species are extinct or critically imperiled.
Speaking of bumble bees, did you see the paper, “Bumble Bees of Montana,” published this week by faculty and students in the Montana State University College of Agriculture in the Annals of the Entomological Society of America (AESA)? The scientists researched and compiled the state's first inventory of bumble bees known to live in Montana.
"The first time a bumble bee was recorded in Montana was in the journals of the Lewis and Clark expedition in 1805," wrote Jenny Lavey of the MSU News Service.
Four scientists co-authored the paper:
- Michael Ivie, associate professor of entomology in the MSU Department of Plant Sciences and Plant Pathology
- Kevin O'Neill, professor of entomology in the MSU Department of Land Resources and Environmental Sciences,
- Casey Delphia, MSU research scientist, and
- Amelia Dolan, former MSU entomology graduate student
"Because of Montana's size, landscape diversity and regional junction of eastern and western geographies, when it comes to bumble bees, Montana hosts a diverse, large and globally relevant community of species,” Ivie said in the news release. “Our research shows 28 different species of Bombus, with four more expected to make the list. That's the largest number of bumble bee species recorded for a state in the entire country."
Said Dolan: "It was amazing because we had people collecting specimens across the state, in varying elevations and diverse ecosystems – areas we alone wouldn't have had access to in the time that we had to complete the project. The number of species is representative of Montana's wild spaces and diverse landscapes that host these bees."
When was Bombus vosnesenskii first recorded in Montana? In 1923 (Frison).
If you want to hear more about bumble bees and other bees (some 1600 species of bees reside in California), be sure to attend a free two-hour presentation on "Bee Aware Bee Cause" at 1:30 p.m., Saturday, Jan. 7 by Robbin Thorp at the Rush Ranch Nature Center, 3521 Grizzly Island Road, Suisun. A worldwide expert on bees, Thorp is a distinguished emeritus professor of entomology at UC Davis who continues his research, writings and bee identification work. (See information on the event on previous Bug Squad blog.)
How it all began: Pollination ecologist Neal Williams, associate professor in the UC Davis Department of Entomology and Nematology and postdoctoral researcher Rosemary Malfi set out to research how the short-term loss of floral resources affects bumble bees, specifically the yellow-faced bumble bee, Bombus vosnesenskii, a common bumble bee native to the West Coast of the United States. Its importance to agriculture, including the pollination of greenhouse tomatoes, cannot be overstated.
So, "the bee team," led by Williams, decided they needed to weigh the bees as part of their research. They engaged mechanical and electrical engineers on the UC Davis campus to see if they could come up with a "bee scale" to weigh individual foragers.
They could and they did. The project is underway in a field west of the central UC Davis campus. The site includes fine-mesh tents filled with wildflowers to contain the bumble bees and an RV converted into a lab.
Fell began his piece with "How do you weigh a bee?"
"That's the question that brought together insect specialists at the University of California, Davis, and two teams of UC Davis engineering students this year, to try and solve what turns out to be a tricky technical problem," Fell wrote. "But the consequences are important: ultimately, understanding how California's native bumble bees respond to changes in the environment and the availability of flowers, and how we can protect these insects that are so vital to both agriculture and wild plants."
The entomologists worked with electrical engineers Anthony Troxell, Jeff Luu and Wael Yehdego, advised by Andre Knoesen, professor in the Department of Electrical and Computer Engineering, and mechanical engineers Lillian Gibbons, Laurel Salinas and Ryan Tucci, advised by Professor Jason Moore.
Fell wrote: "The electrical engineers had to solve the problem of taking the raw signal from the scale and obtaining time-stamped data for individual bees."
“We were working with very small signals, at the low end of the technology, so noise in the data was an issue,” Troxell related in the news story. "A bumble bee weighs between 150 and 200 milligrams, and to get useful information about bee health or how much pollen they are carrying, the scale would need to be accurate to less than one milligram. A conventional laboratory balance averages several readings over a few seconds — but bees are much too fast and jittery for that to work."
Williams described the bee scale as "a great example of interdisciplinary work." And indeed it is.
This project is sure to gain national and international attention. It's not just about the plight of the bumble bees but the unique collaboration between entomologists and engineers and the resulting device they successfully designed and crafted.
What's better than sighting a yellow-faced bumble bee, Bombus vosnesenskii?
Well, a newly emerged Bombus vosnesenskii queen.
On the last day of June, we spotted this fresh queen-looking foraging on our blanket flower (Gaillardia). Her jet-black color, sunny yellow markings, and untattered wings indicated that this was one of her first flights. Queen bees are huge--about 18 to 21mm long--much larger than the other bees in her colony. Workers (females) range from 8 to 17 mm while males measure between 10 and 15mm.
The queen took a liking to the blanket flower, buzzing from blossom to blossom and sharing communal meals--sweet nectar--with honey bees, longhorned bees, and carpenter bees. A camouflaged crab spider, sprawled out on the top of a blossom, itched to get in on the feeding action by snagging an inattentive bee, but the bees buzzed right past their would-be predator. Not today!
Bombus vosnesenskii is one of only 250 species in the genus Bombus, which is Latin for "buzzing." Native to the west coast of North America, Bombus vosnesenskii is considered the most abundant bumble bee from British Columbia to Baja California. Its importance to agriculture is crucial: it's commonly invited to pollinate commercial greenhouse tomatoes, which it does very well. The next time you eat a greenhouse tomato, you should probably thank Bombus vosnesenskii.
Want to learn more about bumble bees? Native pollinator specialist Robbin Thorp, distinguished emeritus professor of entomology at the University of California, Davis, is the co-author of the landmark Bumble Bees of North America: An Identification Guide (with co-authors Paul H. Williams, Leif L. Richardson and Sheila R. Colla), published by Princeton University Press. It's the winner of a 2015 Outstanding Reference Sources Award, Reference and User Services Association, American Library Association.
Want to hear a bumble bee buzz? Just click this link: Bumble Bees of North America: An Identification Guide.
It's almost like bee-ing there.
The next time you see a yellow-faced bumble bee (Bombus vosnesenskii) packing pollen, check out the color.
Last Saturday on an outing in Vallejo overlooking the Carquinez Straits, we noticed a yellow-faced bumble bee on an Echium candicans (Pride of Madeira) packing red pollen, as brilliant as a sun-ripened strawberry.
It probably picked up the red pollen from the nearby California golden poppies--not from the Echium because Echium pollen is a bluish/lavender.
The yellow-faced bumblebee, so called because of its yellow face, is native to the west coast of North America. In the global line-up, it's one of some 250 species of bumble bees--all within the genera Bombus, which is Latin for buzzing or humming.
Bombus vosnesenkii is easily identifiable by its yellow face and the yellow stripe or band at the T4 segment of its thorax.
Want to learn more about bumble bees and how to identify them? Robbin Thorp, distinguished emeritus professor of entomology at the University of California, Davis, co-authored the landmark publication, Bumble Bees of North America: an Identification Guide (Princeton University Press) with Paul Williams, Leif Richardson and Sheila Colla. It won a 2015 Outstanding Reference Sources Award from the Reference and User Services Association, American Library Association.
There's increasing interest in bumble bees--and rightfully so--due to the critical role they play in our ecosystems. Bumble Bees of North America is described as "the first comprehensive guide to North American bumble bees to be published in more than a century."
We haven't seen many bumble bees this year, but as spring temperatures warm up and blossoms beckon, they'll be out there foraging.
Graced with many colors of pollen.