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."
Bumble bees foraging on almond blossoms.
Make that the yellow-faced bumble bees, Bombus vosnesenskii, in Benicia.
Sunday morning as the temperatures soared to 62 degrees in the Matthew Turner Park, Benicia, near the Carquinez Straits, bumble bees competed with honey bees for a share of the golden nectar on the blossoming almond trees.
We witnessed near collisions as lumbering bumble bees lugged incredibly heavy loads while their more streamlined cousins, the honey bees, darted, ducked and dipped to avoid them. Definitely a need for air traffic controllers!
"Bumble bee, bumble bee, cleared for take-off."
"Honey bee, honey bee, stand by."
"Bumble bee, bumble bee, permission to land."
"Honey bee, honey bee, exit runway."
"Bumble bee, bumble bee, line up and wait."
"Honey bee, honey bee, cleared for take-off."
What a sight to see and what a beauty of a day to see bumble bees in Benicia.
Bring on the bumble bees!
In yesterday's Bug Squad blog, we mentioned the unusual first-of-the-year bumble bee sightings at the Benicia Capitol State Historic Park. We captured images of the yellow-faced bumble bees, Bombus vosnesenskii, nectaring on jade, Crassula ovata, the morning of Jan. 1, 2018. They were packing cream-colored pollen.
Bombus vosnesenskii were also out and about at the Benicia Marina--same morning, same day--but on a different floral species: rosemary, Rosmarinus officinalis. This flower, too, yields a cream-colored pollen.
But wait! The bumble bees we saw foraging on the rosemary were packing orange pollen, as bright as Halloween pumpkins.
What happened? They didn't get it from the rosemary. It came from another plant, perhaps the early blooming California golden poppies which yield orange pollen (and no nectar).
Rosemary, which blooms nearly year-around in this area, belongs to the mint family, Lamiaceae, which also includes peppermint, spearmint, basil, lavender, marjoram, germander, thyme, savory, and horehound. One of the distinguishing features in this family: square stems.
When you think about it, rosemary's presence at the marina is quite appropriate. It derives its name from the Latin "dew" (ros) and "sea" (marinus), or "dew of the sea."
While folks from Alaska to Colorado to New York to Maine are shivering in freezing temperatures, here in sunny California--well, at least parts of the Golden State are sunny--bumble bees are foraging on winter blooms.
Bumble bees? On the first day of the year?
Yes. We spotted a dozen yellow-faced bumble bees, Bombus vosnesenskii, nectaring this morning in Benicia, Solano County, Calif.
They were foraging on jade at the Benicia Capitol State Historic Park and on rosemary at the Benicia Marina. Honey bees and syrphid flies joined them. We also saw some hungry predators--birds--chasing them.
For the last several years, several of us bumble bee aficionados--led by Robbin Thorp, distinguished emeritus professor of entomology at the University of California, Davis--seek to find and photograph the first bumble bee of the year.
Last year the big winner was naturalist and insect photographer Allan Jones of Davis. At 2:02 p.m., on Friday, Jan. 27, he alerted us: "Two Bombus melanopygus on manzanita just east of the redwood grove (UC Davis Arboretum)."
And then he found another melanopygus. It was a three-in-one day.
The story behind the story: Inspired by Robbin Thorp, a small group of eager bumble bee aficionados--naturalists and insect photographers Gary Zamzow and Allan Jones of Davis, and yours truly of UC Davis--launched the First-Bumble-Bee-of-the-Year Contest six years ago.
It's a take-off of Art Shapiro's "Beer for a Butterfly" contest. Shapiro, a distinguished professor of evolution and ecology at UC Davis, offers a pitcher of beer for the first cabbage white butterfly (Pierae rapae) of the year found in the three-county area of Sacramento, Yolo and Sacramento. He launched the contest in 1972 as part of his long-term studies of butterfly life cycles and climate.
For us bumble bee aficionados, the prize isn't a pitcher of beer. There's no prize. It's basically to provide a few more eyes to help Robbin Thorp track early-season bumble bees.
Thorp is the co-author of Bumble Bees of North America: An Identification Guide (Princeton University Press) and California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday).
Meanwhile, look around for bumble bees in your area. You won't find them in the "deep freeze" states like Alaska, North Dakota or Minnesota. And you certainly won't find them in Hettinger, N.D., where the temperature dipped to a negative 45 degrees today.
But if you're in Benicia or another sunny place, it's a Bumble Bee Kind of Day and what a way to begin the New Year!
Happy New Year!
Honey bees aren't the only bees out foraging.
We saw our first native bee of the season on Jan. 25 at the Benicia Capitol State Historic Park.
Native pollinator specialist Robbin Thorp, distinguished emeritus professor of entomology at the UC Davis Department of Entomology and Nematology, identified it as a female sweat bee, Halictus rubicundus.
"The head shape, lack of long curled hairs below at the base of the hind leg, and the bent basal vein in the wing" helped him identify it as a Halictus. The lack of facial foveae confirmed it was not an Andrena.
"Nice early record for this species," added Thorp, who is the co-author of California Bees and Blooms: A Guide for Gardeners and Naturalists (Heydey) and Bumble Bees of North America: An Identification Guide (Princeton University Press.)
Halicutus rubicundus is found in Europe, northern Asia, and across the United States and Canada, according to the book, The Bees in Your Backyard, A Guide to North America's Bees, by Joseph S. Wilson, assistant professor of biology at Utah State University, and Olivia J. Messinger Carril, who received her doctorate in plant biology from Southern Illinois University and "has been studying bees and wasps for more than a decade," according to the publisher, Princeton University Press.
You can see more images of this sweat bee on BugGuide.Net.
So, one sweat bee down. Hundreds more to go as the seasons unfold.