It's always a delight to see bumble bees and honey bees foraging together on flowers during the winter "sun breaks." Lately we've been seeing them sharing rosemary blossoms in Benicia and Vallejo. 

What does science tell us about this?

In a recently published EurekAlert news story, titled "Research Reveals Why Plant Diversity Is So Important for Bee Diversity," researchers at the Laboratory of Apiculture and Social Insects at the University of Sussex, related that bumble bees have distinct advantages of honey bees.

"In the study, published in the journal Ecology, the researchers used stopwatches to determine how many flowers a bee visited in one minute," according to the news release. "Using a portable electronic balance to weigh each bee, researchers found that, on average, bumble bees are almost twice as heavy as the honey bees. This means that they use almost twice as much energy as honey bees. The stopwatch results showed that they visit flowers at twice the rate of honey bees, which compensate in terms of energy efficiency."

Bumble bees dominated on such species as lavender and "were visiting flowers at almost three times the rate of honey bees."

 "While they forage on the same flowers, frequently we find that bumble bees will outnumber honey bees on a particular flower species, while the reverse will be true on other species growing nearby," said Professor Francis Ratnieks. "What was remarkable was that differences in foraging energy efficiency explained almost fully why bumble bees predominated on some flower species and honey bees on others."

The professor said that in essence, "bumble bees have an advantage over honey bees in being faster at visiting flowers, so can gather more nectar (energy), but a disadvantage in being larger, and so using more of the nectar energy to power their foraging. On some flower species this gave an overall advantage to bumble bees, but on others to honey bees."

(The late Robbin Thorp (1933-2019), distinguished emeritus professor at UC Davis and a global bumble bee expert, told us that bumble bees are earlier risers than honey bees and can forage at lower temperatures. He co-authored Bumble Bees of North America: An Identification Guide (Princeton University Press) and California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday Press). 

The Sussex researchers studied 22 flower species in southern England and analyzed the behavior of more than 1000 bees. They found that "energy efficiency" is a key factor when it comes ot mediating competition.

"Bee body weight and the rate at which a bee visits flowers determine how energy efficient they are when foraging," according to the news article. "Body weight determines the energy used while flying and walking between flowers, with a bee that is twice as heavy using twice as much energy. The rate at which a bee visits flowers, the number of flowers per minute, determines how much nectar, and therefore energy, it collects. Together, the ratio of these factors determines bee foraging energy efficiency. On some flower species such as lavender, bumble bees dominated and were visiting flowers at almost three times the rate of honeybees."

The researchers said that energy (provided by nectar for bees) is a fundamental need, but the fact that honey bees and bumble bees do not compete head on for nectar is reassuring in terms of conservation and co-existence.

As Ratnieks explained: "Bumble bees have a foraging advantage on some plants, and predominate on them, while honey bees have an advantage on others and predominate on these. Bee conservation therefore benefits from flower diversity, so that should certainly be a focus on bee conservation efforts. But fortunately, flowering plants are diverse."

The abstract in Ecology:

"Revitalizing our understanding of species distributions and assembly in community ecology requires greater use of functional (physiological) approaches based on quantifiable factors such as energetics. Here, we explore niche partitioning between bumble and honey bees by comparing a measure of within‐patch foraging efficiency, the ratio of flower visitation rate (proportional to energy gain) to body mass (energy cost). This explained a remarkable 74% of the variation in the proportions of bumble to honey bees across 22 plant species and was confirmed using detailed energy calculations. Bumble bees visited flowers at a greater rate (realizing greater energy benefits) than honey bees, but were heavier (incurring greater energy costs) and predominated only on plant species where their benefit : cost ratio was higher than for honey bees. Importantly, the competition between honey bees and bumble bees had no consistent winner, thus highlighting the importance of plant diversity to the coexistence of competing bees. By contrast, tongue : corolla‐tube‐length ratio explained only 7% of the variation (non‐significant). Our results confirm the importance of energetics in understanding community ecology and bee foraging niche and highlight the energetic tightrope navigated by foraging bees, since approximately half the nectar energy gained was expended in its collection."

Robbin Thorp would have been proud of what happened on Thursday, Jan. 14.

When the UC Davis emeritus professor of entomology, a global authority on bumble bees, died June 7, 2019 at age 85, scientists found a way to memorialize him and what he loved.

The Bohart Museum of Entomology--where Thorp spend much of his time identifying bees, helping scientists, and encouraging guests at open houses to learn about the wonderful world of bees--decided to memorialize him with an annual Robbin Thorp Memorial First-Bumble-Bee-of-the-Year Contest.  The first person to photograph a bumble bee in 2021 in the two-county area of Yolo and Solano would win.

And it is only fitting that Charlie Casey Nicholson, who studied bees with Thorp, won. He photographed a black-tailed bumble bee, Bombus melanopygus, in a manzanita patch  at 3:10 p.m., Thursday, Jan. 14 in the UC Davis Arboretum and Public Garden to claim the honor.  The site is near Old Davis Road.

Due to inclement weather, bumble bees are not easy to find this time of year. Neither are they easy to photograph.

In fact, Nicholson noted this was his seventh observation field trip to look for the first bumble bee of the year. He had searched six previous times (three 10-minute observations on the manzanita on each of two other days, Jan.  6 and 7).

As the winner, Nicholson will receive a special Bohart bumble bee coffee cup and a face mask, said contest coordinator Lynn Kimsey, director of the Bohart Museum and a UC Davis professor of entomology.  

Nicholson, a researcher in the UC Davis Department of Entomology and Nematology labs of Professor Neal Williams, a pollination ecologist, and Extension apiculturist Elina Lastro Niño, is a 2015 alumnus of The Bee Course, where Robbin Thorp, a UC Davis distinguished professor of entomology, taught from 2002 through 2018.  The nine-day intensive workshop, geared for conservation biologists and pollination ecologists and considered the world's premiere native bee biology and taxonomic course, takes place annually in Portal, Ariz., at the Southwestern Research Station, part of the American Museum of Natural History, N.Y.  

"It is truly an honor to win the contest," said Nicholson. "I was a student of Robbin's during the 17th annual Bee Course in Portal, Ariz. I will never forget him wielding his canopy net."  

"The first night (8/17/2015) he gave the opening seminar--a whirlwind tour of what makes a bee. It was so exciting to be at this research station surrounded by people whose names you've read all the time.”

“Robbin helped me learn to pay close attention to the arolia of Anthidiini. As we moved into identifying bees, Robbin was a great teacher as we worked through the dichotomous keys in The Bee Genera of North and Central America: Hymenoptera Apoidea. He always had some morphological signpost that wouldn't give away the 'answer' but would certainly guide you in the right direction." 

Charlie holds a bachelor of arts degree in biology (evolution, ecology and behavior), 2010, cum laude,  from Skidmore College, Saratoga Springs, New York. He received his doctorate in natural resources in 2018 from the University of Vermont, where he was a Gund Institute for Environment graduate fellow. In his dissertation, he examined how landscape and farm management affect the multiple benefits provided by wild bees. 

Nicholson joined UC Davis as a postdoctoral scholar in the spring of 2019, and receives funding support from the USDA Invasive Species and Pollinator Health Unit. He recently co-authored a paper, “Natural Hazard Threats to Pollinators and Pollination,” published in the journal Global Change Biology, that analyzed 117 published research papers on natural hazards that threaten pollinators and pollination. 

His other interests include multiple dimensions of biodiversity, conservation planning, agricultural management, ecosystem services, and community and landscape ecology. 

Robbin Thorp 
Thorp, a member of the UC Davis entomology faculty for 30 years, from 1964-1994, died June 7, 2019 at his Davis home at age 85. A tireless advocate of pollinator species protection and conservation, Thorp was known for his expertise, dedication and passion in protecting native pollinators, especially bumble bees, and for his teaching, research and public service. He was an authority on pollination ecology, ecology and systematics of honey bees, bumble bees, vernal pool bees, conservation of bees, native bees and crop pollination, and bees of urban gardens and agricultural landscapes.

He achieved emeritus status in 1994 but continued to engage in research, teaching and public service until a few weeks before his death. In 2014, he co-authored two books Bumble Bees of North America: An Identification Guide (Princeton University, 2014) and California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday, 2014).

Every summer from 2002 to 2018, Thorp volunteered his time and expertise to be one of the instructors in The Bee Course. In a 2013 interview with the UC Davis Department of Entomology and Nematology, Thorp said he loved teaching at The Bee Course and praised the co-instructors and students. "Ron McGinley who got his undergraduate degree at UC Davis does most of the initial student contact and scheduling for the course. Steve Buchmann, who got his PhD at UC Davis in 1978, is one of the instructors.  There are usually about eight instructors and 22 participants for the course.  Most of the time is spent in the lab identifying bees to genus.  At least three days are spent in the field so students can see various bees doing their thing, collect them and bring them back to the lab to identify them.  It is a great experience for students to interact with instructors and especially with their peers from around the world.  Instructors all donate their time to teach in the course, but benefit from the chance to get together with colleagues and a new cohort of interesting students each year.  Every class is different (that is, it takes on its own personality) and each student brings something new and different to the mix."

Robbin Thorp would have been proud of what happened on Thursday, Jan. 14.  

They're out there!

Yes, after a l-o-n-g, cold, hard winter, bumble bees are emerging.

At least in Solano County. 

At 11:20 a.m. today (Wednesday, Jan. 13), we spotted a yellow-faced bumble bee, Bombus vosnesenskii, foraging on oxalis near downtown Benicia. 

What a delight! A January bumble bee and the first one we've seen this year. 

So, this is a good time to mention the inaugural Robbin Thorp First-Bumble-Bee-of-the-Year Contest, sponsored by the Bohart Museum of Entomology and coordinated by Bohart director Lynn Kimsey, UC Davis professor of entomology. 

Just photograph a clearly identifiable bumble bee in the two-county area of Yolo or Solano, and submit it to bmuseum@ucdavis.edu with the time, date and place. The winner receives bragging rights and a special gift from the Bohart Museum. Plans call for a Bohart coffee mug with a bumble bee image.

The contest memorializes native pollinator specialist and Bohart associate Robbin Thorp (1933-2019), UC Davis distinguished emeritus professor of entomology. Professor Thorp, 85, who died June 7, 2019, was a global authority on bumble bees, and always looked forward to seeing the first bumble bee of the year.  He launched an impromptu contest several years ago with a small group of bumble bee enthusiasts/photographers (including yours truly) from Yolo and Solano counties.  (Note: I am not a contestant.)

Early Bumble Bees
The black-tailed bumble bee, Bombus melanopygus, is usually the first bumble bee to emerge in this area, Thorp used to say. It forages on manzanitas, wild lilacs, wild buckwheats, lupines, penstemons, clovers, and sages, among others. In early January, it's often seen on manzanita blossoms in the UC Davis Arboretum and Public Garden. B. vosnesenskii forages on such early bloomers as oxalis, jade, mustard and wild radish, and then on a variety of plants throughout the year. Both species are natives.

Thorp, a 30-year member of the UC Davis entomology faculty, from 1964-1994,  co-authored two books, Bumble Bees of North America: An Identification Guide (Princeton University, 2014) and California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday, 2014). He achieved emeritus status in 1994 but continued to engage in research, teaching and public service until a few weeks before his death.

A tireless advocate of pollinator species protection and conservation, Thorp was known for his expertise, dedication and passion in protecting native pollinators, especially bumble bees, and for his teaching, research and public service. He was an authority on pollination ecology, ecology and systematics of honey bees, bumble bees, vernal pool bees, conservation of bees, native bees and crop pollination, and bees of urban gardens and agricultural landscapes. 

Ready to join the hunt for the first bumble bee of the year in Yolo and Solano counties? Camera ready? Walking shoes laced? Go!

Seen any bumble bees lately in Yolo or Solano counties?

If so, and if you photograph the first one of the year, you might win the Bohart Museum of Entomology's contest.

In memory of native pollinator specialist Robbin Thorp (1933-2019), UC Davis distinguished emeritus professor of entomology, the Bohart Museum is sponsoring the inaugural Robbin Thorp Memorial First-Bumble-Bee-of-the-Year Contest.

Professor Thorp, 85, who died June 7, 2019, was a global authority on bumble bees, and always looked forward to seeing the first bumble bee of the year.  He launched an impromptu contest several years ago with a small group of bumble bee enthusiasts/photographers from Yolo and Solano counties.  

Now the Bohart Museum, where Thorp spent much of his time identifying bees and helping others, is sponsoring the contest. Participants are to capture an image of a bumble bee in the wild in either Yolo or Solano counties and email the image to bmuseum@ucdavis.edu, with the details of time, date and place. The image must be recognizable as a bumble bee.  The winner receives bragging rights and a special gift from the Bohart Museum, said Lynn Kimsey, director of the Bohart and UC Davis professor of entomology. Plans call for a Bohart coffee mug with a bumble bee image.

The first bumble bee to emerge in this area is the black-tailed bumble bee, Bombus melanopygus. Native to western North America and found from California to British Columbia and as far east as Idaho, it forages on manzanitas, wild lilacs, wild buckwheats, lupines, penstemons, clovers, and sages, among others.

Thorp, a 30-year member of the UC Davis entomology faculty, from 1964-1994, co-authored two books, Bumble Bees of North America: An Identification Guide (Princeton University, 2014) and California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday, 2014). He achieved emeritus status in 1994 but continued to engage in research, teaching and public service until a few weeks before his death.

A tireless advocate of pollinator species protection and conservation, he was known for his expertise, dedication and passion in protecting native pollinators, especially bumble bees, and for his teaching, research and public service. He was an authority on pollination ecology, ecology and systematics of honey bees, bumble bees, vernal pool bees, conservation of bees, native bees and crop pollination, and bees of urban gardens and agricultural landscapes.

Thorp co-taught The Bee Course from 2002 to 2019, an intensive nine-day workshop affiliated with the American Museum of Natural History and held annually at the Southwestern Research Station, Portal, Ariz.

Kimsey, who first met Thorp when she was a graduate student at UC Davis, said that although he wasn't her major professor, “my project was on bees and he was incredibly helpful and supportive. His enthusiasm about pollinators and bees in particular actually grew after he retired, and he continued helping students and researchers and was the backbone of so much research. His support and kindness was matched by his undemanding assistance and expertise. What a terrible loss to his family and to the research and conservation communities." 

An authority on the critically imperiled Franklin's bumble bee, Bombus franklini,  Thorp began monitoring the bumble bee population in 1998 in its narrow distribution range of southern Oregon and northern California. He had not seen it since 2006 and was instrumental in placing Franklin's bumble bee on the Red List of Threatened Species of the International Union for Conservation of Nature and Natural Resources (IUCN). Long active in the North America IUCN Bumblebee Specialist Group, Thorp served as its regional co-chair, beginning in 2011. 

In August of 2016 a documentary crew from CNN, headed by John Sutter, followed Thorp to a meadow where he last saw Franklin's bumble bee. Sutter wrote about Dr. Thorp, then 82, in a piece he titled "The Old Man and the Bee," aspinoff of Ernest Hemingway's "The Old Man and the Sea." (See "Will Franklin's Bumble Bee Ever Be Seen Again?"on YouTube by EarthFixMedia.)

Highly honored by his peers, Thorp was named a fellow of the California Academy of Sciences, San Francisco in 1986; recipient of the Edward A. Dickson Emeriti Professorship of UC Davis in 2010; and recipient of the UC Davis Distinguished Emeritus Award in 2015. Other honors included: member of the UC Davis Bee Team that won the Team Award from the Pacific Branch, Entomological Society of America (PBESA) in 2013. In addition, he was a past president (2010-2011) of the Davis Botanical Society, and former chair (1992-2011) of the Advisory Committee for the Jepson Prairie Reserve, UC Davis/Natural Reserve System. 

UC Davis professor and pollination ecologist Neal Williams, who organized a special symposium in Thorp's honor at the 2019 PBESA meeting in San Diego, praised his “tireless efforts in research, advocacy and education” and how he “inspired a new generation of bee researchers.”