- Author: Kathy Keatley Garvey
Its population is declining and he feared it might become extinct. B. occidentalis, sometimes called the "white-bottomed bee" due to its distinctive white markings on its abdomen, is known for pollinating blackberries, cherries, apples and blueberries.
Fast forward to today and the UC Davis research on how climate change is "rapidly restructuring North American bumble bee communities."
Newly published research from the laboratory of Professor Neal Williams, a pollination ecologist in the UC Davis Department of Entomology and Nematology (and close friend and colleague of Thorp), indicates a substantial shift in bumble bee communities.
The analytical paper, “Warming Summer Temperatures Are Rapidly Restructuring North American Bumble Bee Communities” --authored by ecologist Jeremy Hemberger, a former postdoctoral fellow in the Williams lab, and Professor Williams--appears in Ecology Letters.
“This is one of the first papers to show really substantial shifts in community composition in bumble bees due to climate, but also in insects more broadly,” said Hemberger, now a postdoctoral researcher at his alma mater, the University of Wisconsin, Madison. “We're also able to partition the effect we found to being driven by a loss of cold-adapted species, and a rapid rise in warm-adapted species across North America, but alarmingly we see that, above 50° parallel north, even warm-adapted species are declining.”
The 50th parallel north is a circle of latitude that is 50 degrees north of the Earth's equatorial plane. It crosses Europe, Asia, the Pacific Ocean, North America and the Atlantic Ocean. At this latitude, the sun is visible for 16 hours and 22 minutes during the summer solstice, and 8 hours, 4 minutes during the winter solstice, according to Wikipedia.
“Though additional confirmation is needed, our results suggest that northern bumble bee communities may be in crisis, with significant species turnover and declines in abundance that may threaten the persistence of populations in the coming decades,” they wrote.
“Overall, our work provides strong evidence of the pervasive impacts a warming planet has for insect biodiversity, particularly for historically cool-adapted species,” they related. “It also identifies regions of concern where anthropogenic climate warming is rapidly restructuring the communities of an ecologically important group of insects.”
They used along-term dataset of North American bumble bee species occurrences to determine whether the community temperature index (CTI), a measure of the balance of warm- and cool-adapted species in a community, has increased given warming temperatures. The database of 781,280 records from 1805 to 2020 was derived from a variety of sources, including natural history collections, research studies, and citizen science programs. To match the temporal range of available climate data, they used bumble bee records collected between 1960 and 2018.
“Over the last 29 years across the continent, bumble bee communities increasingly consist of fewer cool-adapted and more warm-adapted species with resultant increases in the community temperature index, a measure of the balance of warm- and cool-adapted species,” they wrote. “Changes are most pronounced at mid- to high latitudes and high elevations in the American Rockies, Intermountain West and central Mexico.”
Their project, launched in 2020 and completed in 2023, focused on 59 species. All California bumble bees were included in the analysis. The authors noted that the long-term, rising summer temperatures are “particularly alarming” to the Western bumble bee, Bombus occidentalis; the two-formed bumble bee, B. bifarius of Western North America; and the forest bumble bee, B. sylvicola, a high-altitude specialist native to North America and widely distributed in Canada.
B. occidentalis is one of the cool-adapted species that is declining. The yellow-faced bumble bee, B. vosnesenskii, native to the West Coast, is one of the "biggest winners” per the analysis.
Read the paper at https://onlinelibrary.wiley.com/doi/full/10.1111/ele.14492.
- Author: Kathy Keatley Garvey
We miss the late Robbin Thorp, 1933-2019, distinguished emeritus professor of entomology at UC Davis, who co-authored Bumble Bees of North America: an Identification Guide (Princeton University Press, 2014).
He loved to share his expertise on bumble bees, which originated more than 100 million years ago. But their distribution and diversity are not well known, he used to tell us.
Bumble bees are just one of the some 20,000 species of bees that populate the world. Of that number, however, only about 250 species are bumble bees, and they all belong to the genus Bombus.
Some 46 different species of bumble bees reside in North America, north of Mexico, Thorp related for a Bug Squad blog posted on July 10, 2014.
In their book, lead author Paul Williams and co-authors Thorp, Leif Richardson and Sheila Colla published information about bumble bees and their history, plant favorites, distribution maps, up-to-date taxonomy, and extensive keys to identify the many color patterns of the species.
They list sites to spot bumble bees:
- farms and gardens with a diversity of flowering crops and herbs
- hay fields
- roadside ditches
- windbreaks with good abundance and diversity of “weedy” flowering plants, such as clovers and vetches
- wetlands and wet meadows
- hardwood forests
- mountain meadows, and
- urban parks and gardens
The primary species found in Yolo County, Thorp related, are:
- Yellow-faced bumble bee, now known as the Vosnesensky bumble bee, Bombus vosnesenskii
- Yellow bumble bee, Bombus californicus, now known as Bombus fervidus
- Black-tailed bumble bee, Bombus melanopygus, formerly known as Bombus edwardsii. This is the first to fly in the winter and spring.
- Crotch bumble bee, Bombus crotchii, a short-tongued species
- Van Dyke bumble bee, Bombus vandykei, a medium long-tongued species
Lately we've been observing B. vosnesenskii, and B. fervidus, B. melanopygus in our pollinator garden in Vacaville, Solano County.
Currently, B. fervidus favors the rock purslane, Calandrina grandiflora. What a joy to see!
- Author: Kathy Keatley Garvey
The United Nations designated May 20 as World Bee Day to raise awareness of the importance of pollinators, the threats they face and their contribution to sustainable development, according to its website.
It originated in 2018 when the government of Slovenia proposed that the United Nations declare May 20 as World Bee Day.
Why May 20? That was the day Anton Janša (1734-1773), a pioneer of modern apiculture, was born. "Janša came from a family of beekeepers in Slovenia, where beekeeping is an important agricultural activity with a long-standing tradition," relates Apimondia.
Today, however, let's pay tribute to the bumble bees. The late Robbin Thorp (1933-2019), UC Davis distinguished emeritus professor, UC Davis Department of Entomology and Nematology, used to point out there's only one bumble bee genus--Bombus--and that more than 250 species belong to this genus. California has 27 species of Bombus, according to Thorp in his 1983 published research, "Bumble Bees and Cuckoo Bumble Bees of California," written with colleagues Donald Horning Jr. and Lorry Dunning.
In his retirement, Thorp 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).
Thorp, a member of the UC Davis entomology faculty for 30 years (1964-1994), continued his research, teaching and public service until his death in 2019 at age 85.
Franklin's bumble bee, Bombus franklini--a bee that he monitored for decades until his death in 2019--is now protected as an endangered species under the Endangered Species Act (ESA). It is feared extinct. Thorp, the last known person to see Franklin's bumble bee in its native habitat, spotted it in 2006 near Mt. Ashland. The bee inhabits--or did--a 13,300-square-mile area confined to five counties--Siskiyou and Trinity counties in California; and Jackson, Douglas and Josephine counties in Oregon. Its range may be the smallest range of any bumble bee species in North America, or even the world, he mused.
Today scientists are worried about the declining bumble bee population, a decline attributed to climate change, habitat loss, and pesticides. Bumble bees are especially known for their "buzz pollination" of such plants as tomatoes, peppers and cranberries. They help pollinate crops worth an estimated $3 billion in the United States alone.
"Due to threats including habitat loss, pesticide use and disease, sightings of the bee have declined by 89%, and it's disappeared completely from eight states. The decline of this once-common native bee is alarming and heartbreaking — and a harbinger of massive biodiversity loss across the country."--Center for Biological Diversity.
The dominant bumble bee species in California is the yellow-faced bumble bee, Bombus vosnesenskii. The Western bumble bee, B. occidentalis, used to be quite common. "It's one of four bumble bee species cleared by the state's Third Appellate District Court of Appeal for inclusion on California's endangered species list," according to a UC Riverside news story, published in July 2022.
Access the California Bumble Bee Atlas website to see how you can help. Meanwhile, how many species of bumble bees have you seen and photographed in California? Here are some of them.
- Author: Kathy Keatley Garvey
Rukowski, who studies with community ecologists Rachel Vannette, associate professor and vice chair of the UC Davis Department of Entomology and Nematology, and distinguished professor Rick Karban, will present her exit seminar on "Identity and Functions of Symbiotic Fungi Associated with Social Bees" on Monday, May 20.
Her hour-long seminar starts at 4:10 p.m. in Room 122 of Briggs Hall. It also will be on Zoom. The Zoom link:
https://ucdavis.zoom.us/j/9 5882849672.
"Social bees interact with diverse microbial communities that reside in flowers, in their nests, and within their guts," Rutkowski says in her abstract. "Fungi are common inhabitants of these environments, but despite their prevalence, little is known about their interactions with bees and their impacts on bee health. In my thesis, I identified common fungal associates of social bees and investigated their effects on bumble bee health, specifically focusing on their roles in bee response to fungicide, bee nutrition, and protection from pathogens."
"I identified several yeast groups frequently associated with social bees, including the genera Starmerella and Zygosaccharomyces," she relates. "Addition of these yeasts to bee diets improved survival and reproduction, and for one species, helped bees recover from negative effects of fungicide exposure. However, a follow-up study determined that these benefits to bee health are inconsistent and unrelated to bee nutrition. Rather, benefits of these yeasts instead may be mediated through pathogen suppression, as Starmerella yeasts are able to inhibit the growth of multiple fungal pathogens of bees. These results highlight the important impacts of these currently understudied microbes on bumble bee health, with implications for conservation of these pollinators."
In her 2021 ESA presentation, she drew attention to fungicide applications that are linked to declining bumble bee populations. She wrote in her abstract: "Native bees including bumble bees are important pollinators but face threats from multiple sources, including agrochemical application. Declining bumble bee populations have been linked to fungicide application, which could directly affect the fungi often found in the stored food and GI tract of healthy bumble bees. Here, we test the hypothesis that fungicides impact bee health by disrupting bumble bee -fungi interactions. Using two species, Bombus vosnesenskii and B. impatiens, we test the interactive effect of the fungicide propiconazole and fungal supplementation on the survival, reproduction, and microbiome composition of microcolonies (queenless colonies). We found that both bee species benefitted from fungi, but were differentially affected by fungicides. In B. vosnesenskii, fungicide exposure decreased survival while fungal supplementation mitigated fungicide effects. For B. impatiens, fungicide application had no effect, but fungal supplementation improved survival and offspring production. Fungicides altered fungal microbiome composition in both species, and reduced fungal abundance in B. vosnesenskii microcolonies, but not in B. impatiens, where instead fungal addition actually decreased fungal abundance. Our results highlight species-specific differences in both response to fungicides and the nature of fungal associations with bees, and caution the use of results obtained using one species to predict the responses of other species. These results suggest that fungicides can alter bee- fungi interactions with consequences for bee survival and reproduction, and suggest that exploring the mechanisms of such interactions, including interactions within bee-associated fungal communities, may offer insights into bumble bee biology and bumble bee conservation strategies."
Her many activities include:
- A 2023 graduate of The Bee Course, a 10-day workshop on bee collection and identification at the Southwestern Research Station in Portal, AZ.
- Co-chair of the department's entomological activities, 2022 UC Davis Picnic Day, with forensic entomologist Robert Kimsey.
- As a member of the UC Davis graduate student group, Equity in Science, Technology, Engineering, Math, and Entrepreneurship (ESTEME), she helped plan activities and lessons for middle school students in the Davis area.
- Former secretary and vice president of the UC Davis Entomology Graduate Student Association.
- Mentored prospective graduate students from groups underrepresented in STEM through a month-long program, and provided application advice and feedback on application materials.
Rutkowski holds a bachelor of science degree from Cornell University in entomology and biological sciences, with a concentration in ecology and evolutionary biology. She graduated in May 2018 summa cum laude with distinction in research.
At Cornell, Rutkowski did independent research with Professor Jennifer Thaler, carrying out an independent honor's thesis research project on ecological interactions between insect herbivores, plants, and arbuscular mycorrhizal fungi. Rutkowski also worked with Thaler on numerous other projects, studying interactions between potato plants, Colorado potato beetles, and their predators, as well as projects studying the interactions between arbuscular mycorrhizal fungi, tomato plants, and insect herbivores. She also worked with Professor Richard Lindroth at the University of Wisconsin, Madison, investigating how genotype and environmental conditions interact to affect the growth, defense and insect community of aspen trees.
Rutkowsk is the lead author or co-author in a number of publications:
- Rutkowski, D., Weston, M., Vannette, R.L. (2023) Bees just wanna have fungi: A review of bee associations with non-pathogenic fungi. FEMS Microbiology Ecology 99(8) https://doi.org/10.1093/femsec/fiad077
- Karban, R., Rutkowski, D., Murray, N. (2023) Flowers that self?shade reduce heat stress and pollen limitation. American Journal of Botany 110(2) https://doi.org/10.1002/ajb2.16109
- Pepi, A., Pan, V., Rutkowski, D., Mase, V., Karban, R. (2022) Influence of delayed density and ultraviolet radiation on caterpillar baculovirus infection and mortality. Journal of Animal Ecology 91(11):2192-2202 https://doi.org/10.1111/1365-2656.13803
- Rutkowski, D., Litsey, E., Maalouf, I, Vannette, R.L. (2022) Bee-associated fungi mediate effects of fungicides on bumble bees. Ecological Entomology 47(3):411-422 https://doi.org/10.1111/een.13126
- Mola, J.M., Stuligross, C., Page, M.L., Rutkowski, D., Williams, N.M. Impact of “non-lethal” tarsal clipping on bumble bees (Bombus vosnesenskii) may depend on queen stage and worker size. Journal of Insect Conservation 25, 195–201 (2021). https://doi.org/10.1007/s10841-021-00297-9
The UC Davis Department of Entomology and Nematology seminars are coordinated Brian Johnson, associate professor. For any technical issues with Zoom, contact him at brnjohnson@ucdavis.edu. The full list of spring seminars is here.
- Author: Kathy Keatley Garvey
With the Entomological Society of America (ESA), however, being framed is a good thing. No, a great thing!
ESA honors its President's Prize winners (aka first-place winners) in the student research competitions by asking them to step behind a cardboard cut-out and smile for the camera. Voila! Suitable for framing!
Joe Rominiecki, ESA manager of communications, just announced that the images are now available and we have permission to share them.
We earlier wrote that doctoral candidates Danielle Rutkowski and Zachary Griebenow of the UC Davis Department of Entomology and Nematology each won the President's Prize for their individual research presentations at the 2022 Joint Meeting of the Entomological Societies of America, Canada, and British Columbia, held Nov. 13-16 in Vancouver, British Columbia.
And now, we have the images.
Background: At the annual ESA meetings, students are offered the opportunity to present their research and win prizes. They can compete in 10-minute papers (oral), posters, or infographics. The President's Prize winners receive a one-year paid membership in ESA, a $75 cash prize, and a certificate. Second-winners score a one-year free membership in ESA and a certificate.
Rutkowski, who studies with community ecologists Rachel Vannette, associate professor, and distinguished professor Richard “Rick” Karban, spoke on “The Mechanism Behind Beneficial Effects of Bee-Associated Fungi on Bumble Bee Health,” at her presentation in the category, Graduate School Plant-Insect Ecosytems: Pollinators.
Her abstract: "Bees often interact with fungi, including at flowers and within bee nests. We have previously found that supplementing bumble bee colonies with these bee-associated fungi improves bee survival and increases reproductive output, but the mechanisms behind these effects are unclear. This research aimed to determine the mechanisms underlying positive impacts of fungal supplementation in the bumble bee, Bombus impatiens. We tested two hypotheses regarding possible nutritional benefits provided by bee-associated fungi. These included the role of fungi as a direct food source to bees, and the production of nutritionally important metabolites by fungi. To test these mechanisms, we created microcolonies bumble bees and exposed each microcolony to one of four treatment groups. These four treatments were created based on the presence of fungal cells and the presence of fungal metabolites. We found that bee survival and reproduction were unaffected by treatment, with trends of decreased survival and reproduction when fungi were present. This contradicts previous results we've found using this bumble bee species, where fungi had a positive impact. It is possible that this disparity in results is due to differences in pathogen pressure between the two experiments, as bees in the first experiment were exposed to large amounts of pathogen through provided pollen, including Ascosphaera and Aspergillus. This pollen was sterilized for subsequent experiments, reducing pathogen load. Therefore, it is possible that bee-associated fungi benefit bees through pathogen inhibition, and future work exploring this hypothesis is necessary to fully understand the role of these fungi in bumble bee health."
Zachary Griebenow. Griebenow, who studies with major professor and ant specialist Phil Ward, (Griebenow also captained the UC Davis Entomology Games Team in its national championship win at the Entomology Games or Bug Bowl) explained “Systematic Revision of the Obscure Ant Subfamily Leptanillinae (Hymenoptera: Formicidae), Reciprocally Informed by Phylogenomic Inference and Morphological Data.” His category: Graduate School Systematics, Evolution and Biodiversity: Evolution 1.
His abstract: "Ants belonging to the subfamily Leptanillinae (Hymenoptera: Formicidae) are sister to nearly all other extant ants. Miniscule and subterranean, little is known of their behavior. Contrary to the collecting bias observed in most ants, male leptanilline specimens are acquired more easily than workers or queens. The sexes are almost never collected in association, and many subclades within the Leptanillinae are known from male specimens only. Our comprehension of evolutionary relationships among the Leptanillinae is further obstructed by oft-bizarre derivation in male phenotypes that are too disparate for phylogeny to be intuited from morphology alone. These restrictions plague our understanding of the Leptanillinae with probable taxonomic redundancy. My thesis aims at leptanilline taxonomy that reflects phylogeny, inferred from both genotype and phenotype, and integrates morphological data from both sexes. Here I present the results of (1) phylogenomic inference from ultra-conserved elements (UCEs), compensating for potential systematic biases in these data, representing 63 terminals; and (2) Bayesian total-evidence inferences from a handful of loci, jointly with discrete male morphological characters coded in binary non-additive or multistate fashion. Notably, these analyses identify worker specimens belonging to the genera Noonilla and Yavnella, which were heretofore known only from males. Given such discoveries across the Leptanillinae, the number of valid leptanilline genera is reduced from seven to three in order to create a genus-level classification that upholds monophyly along with diagnostic utility."
We also salute our second-place winners (see previous news story:
- Lindsey Mack, who studies with medical entomologist-geneticist Geoffrey Attardo, assistant professor, covered “Three Dimensional Analysis of Vitellogenesis in Aedes aegypi Using Synchrotron X-Ray MicroCT” in the category, Graduate School Physiology, Biochemistry and Toxicology: Physiology
- Addie Abrams, who studies with Extension agricultural entomologist and assistant professor Ian Grettenberger, titled her research, “Hitting the Mark: Precision Pesticide Applications for the Control of Aphids in California Lettuce" in the category, Graduate School Physiology, Biochemistry and Toxicology: Integrated Pest Management
Congrats, all! They do our department and our university proud!
(The 7000-member ESA, founded in 1889, is the largest organization in the world serving the professional and scientific needs of entomologists and individuals in related disciplines. Its members, affiliated with educational institutions, health agencies, private industry, and government, are researchers, teachers, extension service personnel, administrators, marketing representatives, research technicians, consultants, students, pest management professionals, and hobbyists.)