There they were. Together.

The scene: A honeybee (Apis mellifera) and a bumblebee (Bombus vosnesenskii) nectaring on a purple coneflower (Echinacea purpurea) in a UC Davis bee garden.

If you've observed honeybees and wild bees foraging in your garden, you've probably wanted to compare them. Is the honey bee the most effective pollinator?

Newly published UC Davis research in the American Journal of Botany yields some surprising results.

Honeybees are effective pollinators, but when compared to other pollinators, including wild bees, they are rarely the most effective plant pollinators, according to a meta-analysis project led by doctoral candidate Maureen Page and postdoctoral researcher Charlie Casey Nicholson of the Neal Williams laboratory, UC Davis Department of Entomology and Nematology.   

Page and Nicholson are the co-leading authors of "A Meta-Analysis of Single Visit Pollination Effectiveness Comparing Honeybees and other Floral Visitors," the cover story of the current edition of the journal, published Nov. 30.  

“Although high visitation frequencies make honeybees important pollinators, they were rarely the most effective pollinators of plants and were less effective than the average bee,” said Page.  “This suggests that honeybees may be imperfect substitutes for the loss of wild pollinators and ensuring pollination will benefit from conservation of non-honeybee taxa. In the future, we hope other researchers will use the data we have collected to further investigate the factors that influence pollination effectiveness.

Page and Nicholson originated the idea for the project during a graduate seminar led by UC Davis professor and community ecologist Louie Yang in the winter of 2020. While the COVID-19 pandemic shut down or postponed many other research projects, Page and Nicholson forged ahead and organized fellow graduate students and postdoctoral students to collectively read and extract single visit-effectiveness data from more than 468 papers. The two then analyzed the data from a subset of these papers (168) to ask whether honeybees and other floral visitors differed in their single visit pollination effectiveness. 

Page and Nicholson began with the premise: “Many animals provide ecosystem services in the form of pollination including honeybees, which have become globally dominant floral visitors. A rich literature documents considerable variation in single visit pollination effectiveness, but this literature has yet to be extensively synthesized to address whether honeybees are effective pollinators,”

The researchers conducted a hierarchical meta-analysis of 168 studies and extracted 1564 single visit effectiveness (SVE) measures for 240 plant species. “We paired SVE data with visitation frequency data for 69 of these studies,” they wrote. “We used these data to ask three questions: (1) Do honeybees (Apis mellifera) and other floral visitors differ in their SVE? (2) To what extent do plant and pollinator attributes predict differences in SVE between honeybees and other visitors? (3) Is there a correlation between visitation frequency and SVE?”

They compared honeybees to multiple pollinator groups, including ants, bees, beetles, birds, butterflies, flies, moths, and wasps. 

"Surprisingly, honeybees were less effective than other bees as pollinators of crop plants, suggesting that the importance of honeybees as crop pollinators derives largely from their numerical abundance rather than the quality of their floral visits," Page said. 

 “Honeybees were significantly less effective than the most effective non-honeybee pollinators but were as effective as the average pollinator," they wrote in their results section of the paper. "The type of pollinator moderated these effects. Honeybees were less effective compared to the most effective and average bird and bee pollinators but were as effective as other taxa. Visitation frequency and SVE were positively correlated, but this trend was largely driven by data from communities where honeybees were absent.”

The researchers concluded that “Although high visitation frequencies make honeybees important pollinators, they were less effective than the average bee and rarely the most effective pollinator of the plants they visit. As such, honeybees may be imperfect substitutes for the loss of wild pollinators, and safeguarding pollination will benefit from conservation of non-honeybee taxa.”

Also contributing to the project were Ross Brennan, Anna Britzman, Jessica Greer, Jeremy Hemberger, Hanna Kahl, Uta Müller, Youhong Peng, Nick Rosenberger, Clara Stuligross, Li Wang, and Professors Louie Yang and Neal Williams.

Cover Photo. The cover photo, by Kathy Keatley Garvey, communications specialist, UC Davis Department of Entomology and Nematology, shows several species of bees on a sunflower, Helianthus sp. They include a honeybee  (Apis mellifera), sunflower bee (Svastra obliqua), and two sweat bees (Halictus tripartitus and Halictus ligatus), as identified by Professor Williams, a pollinator ecologist.

"Honeybees are as effective as the average pollinator, but rarely the most effective pollinators of plants," according to the caption. "Surprisingly, honeybees are less effective than other bees as pollinators of cultivated plants, suggesting the importance of honeybees as agricultural pollinators derives largely from their numerical abundance. Their study confirms a widely held belief that honeybees are not the best pollinators of plants globally and substantiates the growing concern that honeybees may be imperfect substitutes for the loss of wild pollinators."

Charlie Nicholson. Nicholson, a researcher in the UC Davis Department of Entomology and Nematology labs of both Professor Neal Williams, and Extension apiculturist Elina Lastro Niño,  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.

Maureen Page. Page received her bachelor's degree in biology, cum laude, from Scripps College, Claremont, Calif., in 2016, and then enrolled in the UC Davis entomology graduate program, with a career goal of becoming a professor and principal investigator. In 2018, she received prestigious three-year fellowship, a National Defense Science and Engineering Graduate Fellowship, for her research proposal, “Promoting Food Security by Optimizing Wildflower Plantings to Support Wild and Managed Bees." Long interested in bee research, Page received a 2013 Scripps Environmental Research Grant to establish a solitary bee monitoring program at the Bernard Field Station in Claremont. She created a reference collection and species list of bee diversity at the field station, gaining experience collecting, pinning and identifying bee specimens. She presented her findings at the Scripps Undergraduate Research Symposium. Page later worked on a project categorizing pollen deposition by the yellow-faced bumble bee, Bombus vosnesenkii to California figwort, Scrophularia california.

Urban garden management can play an important role in supporting species diversity and the provision of insect-mediated services, says ecologist Monika Egerer, an assistant professor at Technical University of Munich (TUM), Germany.

Egerer will speak on "Entomological Investigations in Urban Gardens," focusing on wild bees and natural enemies in urban gardens in Germany, at a virtual seminar hosted by the UC Davis Department of Entomology and Nematology on Wednesday, Nov. 24. 

Her seminar begins at 4:10 p.m., Pacific Time. The Zoom link is here.

More than 60 percent of our world's population will live in cities in the next decades, Egerer says in her abstract. "Urban agriculture has great potential to support arthropod biodiversity and thereby potentially enhance ecosystem services such as pollination and pest predation for more sustainable food production. In this talk, I discuss interdisciplinary research on wild bees and natural enemies in urban community gardens in Berlin and Munich, Germany. Specifically, I examine how urban garden management can play an important role in supporting species diversity and the provision of insect-mediated services. Furthermore, I discuss citizen science initiatives that our group uses to engage the public in scientific research on urban biodiversity and ecosystem services."

Egerer, whose research and teaching interests include ecology, biodiversity, agroecology, urban ecology, insect ecology, climate change, and food systems, holds a bachelor's degree in biology (2013) from Kalamazoo College, Mich., and then received her master's degree (2017) and her doctorate (2019) in environmental studies from UC Santa Cruz, studying with major professor Stacy Philpott.

After research work in Australia, Egerer joined the Institute of Ecology at the Technical University of Berlin in 2019 as an International Postdoc Initiative (IPODI) postdoctoral fellow. In 2020, she was appointed to the professorship for Urban Productive Ecosystems in the TUM School of Life Sciences.

Her most recent peer-reviewed publications include:

• Egerer M and Kowarik I. (2020) Confronting the modern Gordian Knot of urban beekeeping, Trends in Ecology and Evolution 1-4.

• Philpott SM, Egerer M, Bichier P, Cohen H, Cohen R, Liere H, Jha S, Lin BB. (2020) Gardener demographics, experience, and motivations drive differences in plant species richness and composition in urban gardens, Ecology and Society 

• Buchholz S and Egerer M. (2020) Functional ecology of wild bees in cities: what we know about trait-urbanization relationships, Biodiversity and Conservation 1-23.

• Philpott SM, Lucatero A, Bichier P, Egerer M, Jha S, Lin BB, Liere H. (2020) Changes in natural enemy-herbivore networks along local and landscape gradients in urban agroecosystems, Ecological Applications 0: 1-13.

• Egerer M, Lin B, Diekmann L. (2020) Nature connection, experience and policy encourage and maintain adaptation to drought in urban agriculture, Environmental Research Communications 2: 1-12.

• Egerer M, Liere H, Lucatero A, Philpott SM. (2020) Plant damage in urban agroecosystems varies with local and landscape factors, Ecosphere 11(3): 1-19.

• Egerer M, Fouch N, Anderson EC, and Clarke M. (2020) Socio-ecological connectivity differs in magnitude and direction across urban landscapes, Scientific Reports 10: 1-16.

• Egerer M, Wagner B, Lin BB, Kendal D and Zhu K. (2020) New methods of spatial analysis in urban gardens inform future vegetation surveying, Landscape Ecology 1: 1-18. 
  
  
• Egerer M, Cecala JM and Cohen H. (2020) Wild bee conservation within urban gardens and nurseries: effects of local and landscape management, Sustainability 12: 1-10.

The Department of Entomology and Nematology seminars are coordinated by nematologist and assistant professor Shahid Siddique, who may be reached at ssiddique@ucdavis.edu for any technical issues. 

The global decline of pollinators ought to concern everybody, and everybody ought to get involved, said bee conservation researcher Lynn Dicks of the School of Biological Sciences, University of East Anglia, United Kingdom, in her keynote address at the fourth International Pollinator Conference, held July 17-20 at the University of California, Davis.

She spoke on "The Importance of People in Pollinator Conservation" to a capacity crowd gathered July 18 in the ARC Ballroom.

“Who needs to act?" she asked. "Farmers, governments, conservationists, researchers, the general public and businesses.”

Quoting noted biologist/author E. O. Wilson, Dicks said that insects are “the little things that run the world.”

Dicks began her presentation by chronicling news media accounts of “insectageddon,” which Cambridge fellow Robert Macfarlane defined on Twitter as “the current calamitous population decline of insect species globally, with catastrophic results for life on earth.”

One news story, by environment editor Damian Carrington of The Guardian, warned that "The world's insects are hurtling down the path to extinction, threatening a catastrophic collapse of nature's ecosystems." Carrington, in his Feb. 10, 2019 piece, titled “Plummeting Insect Numbers ‘Threaten Collapse of Nature," wrote that “More than 40 percent of insect species are declining and a third are endangered...The rate of extinction is eight times faster than that of mammals, birds and reptiles. The total mass of insects is falling by a precipitous 2.5% a year, according to the best data available, suggesting they could vanish within a century.”

Dicks is widely known for her research and as the lead author of the book, The Bee Conservation: Evidence for the Effects of Intervention (2010, Pelagic Publishing) with co-authors David Showler and William J. Sutherland. The trio worked with international bee experts and conservationists to develop a global list of interventions that could benefit wild bees. The interventions ranged from protecting natural habitat to controlling disease in commercial bumble bee colonies. The book, described as a "thorough guide to what is known, or not known, about the effectiveness of bee conservation actions throughout the world," is the first in a series of Synopses of Conservation Evidence, linked to the online resource, www.ConservationEvidence.com.

“Wild insect pollinators have declined in occurrence, diversity, and in some cases, abundance, in Europe and North America,” Dicks told the crowd. “Lack of data for other regions prevents global assessment of status for insect pollinators, but the main drivers of decline are operating everywhere.”

“Why does pollinator decline matter?” she asked. “Eighty-eight percent of wild plant species depend on pollinators. At least half of the crop pollination serves are provided by wild pollinators—half by managed honey bees.”

Farmers, governments, conservationists, researchers, the general public and businesses must get involved, she reiterated.

What Farmers Should Do

For example, she said, farmers should

• Plant flowers for nectar and pollen
• Manage hedges and forest edges for wildlife
• Restore and protect flower-rich native habitats like meadows, scrubland and woodland
• Provide set aside or fallow areas
• Leave field edges and corners to naturally generate
• Provide nesting sites for bees ("bare ground, big old trees and bee hotels")

What the General Public Should Do

The general public's role should be:

• Grow more flowers, shrubs and trees
• Let your garden grow wild
• Cut your grass less often
• Don't disturb insect nest and hibernation spots
• Think carefully about whether to use pesticides

What Governments Should Do

Dicks touched on 10 "pollinator policies" that governments should do:

1. Raise pesticide regularly standards
2. Promote integrated pest management
3. Include indirect and sublethal effects in GM crop risk assessment
4. Regulate movement of managed pollinators
5. Develop incentives, such as insurance schemes, to help farmers benefit from ecosystem services instead of agrochemicals
6. Recognize pollination as an agricultural input in a extension services
7. Support diversified farming systems
8. Conserve and restore 'green infrastructure” (a network of habitats that pollinators can move between) in agricultural and urban landscapes
9. Develop long-term monitoring of pollinators and pollination
10. Fund participatory research on improving yields in organic, diversified and ecologically intensive farming

Dicks, in her position at the University of East Anglia, engages in research in entomology, agroecology, management of biodiversity and ecosystem services on farms. (See research profile.)

In addition to addressing pollinator decline and "who needs to act and what should they do," the researcher touched on how to motivate people: "insights from the behavioral sciences; and the importance of local knowledge and culture."

Awareness and Understanding Are Not Sufficient

She offered key insights from behavioral science, noting that "awareness and understanding are not sufficient; decisions are not always rational; social norms are important; peer-to-peer communication within social groups drives behavior change and people must feel ABLE to act in their current context."

Dicks recommended that the attendees become acquainted with the work of the coalition Promote Pollinators (https://promotepollinators.org). An excerpt from the website: "Pollinators play a key role in the conservation of biological diversity, ecosystems, food production and the global economy. The effects of current human activities hamper animal pollination. Promote Pollinators, the Coalition of the Willing on Pollinators, reaches out to potential new partners to develop and implement national pollinator strategies. The coalition believes that country-led politics can foster policy measures and innovative action on protecting pollinators."

She also cited the work of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES)

Dicks described pollinator decline as "a complex issue." People--including some politicians--have to change to help protect the pollinators and the ecosystem.

How Some Politicians Use Science

Dicks quoted author Mark Avery, former director of conservation at the Royal Society for the Protection of Birds: "I have rarely seen a policy argument won through logic and science, even though everybody pretends that they are. No, politicians use science like a drunk uses a lamp post--more for support than for illumination."

The conference, “Multidimensional Solutions to Current and Future Threats to Pollinator Health,” covered a wide range of topics in pollinator research: from genomics to ecology and their application to land use and management; to breeding of managed bees; and to monitoring of global pollinator populations. (See agenda.)

Dicks keynoted the conference on Thursday morning, July 18, and Christina Grozinger, distinguished professor of entomology and director of the Center for Pollinator Research, Pennsylvania State University, delivered a keynote address on Friday, July 19, discussing "Bee Nutritional Ecology: From Genes to Landscapes."

Pollination ecologist and professor Neal Williams and Extension apiculturist Elina Lastro Niño, both of the UC Davis Department of Entomology and Nematology, co-chaired the conference. Amina Harris, director of the UC Davis Honey and Pollination Center, and events manager Elizabeth Luu coordinated the four-day event.

Presenters from 15 Countries

Williams said that presenters represented 15 countries: Australia, Thailand, Korea, Japan, Colombia, Brazil, Israel, Mexico, France, Germany, Spain, Sweden, United Kingdom, Canada, and the United States. "And we had at least one attendee from China--although not presenting."

"This was the fourth International Conference on Pollinator Biology, Health and Policy," Williams said. "Each time we try to add new elements that address emerging challenges and new directions in research. This year's sessions felt as fresh and innovative as ever, adding symposia on climate change, innovative monitoring and data collection, and urban bees. By restricting presenters to those who had not presented in the past six years we also added new voices and perspectives."

"We also grew.  In the past the conference has been just under 200 attendees. This year it topped 250, and we had to turn away several people because we simply could not fit more into the space. We added a second evening of posters to provide more time to interact. The response was overwhelming with 112 poster presenters!"

Williams said that the conference "also added more explicit policy elements by creating a set of ViewPOINTS documents summarizing key areas in pollinator biology and heath that target policy makers. This has allowed for collaborative interaction across the attendees and a set of deliverable products from our interactions."

The UC Davis Honey and Pollination Center, directed by Amina Harris, coordinated the conference, with events manager Elizabeth "Liz" Luu serving in the lead role. 

"It was an amazing team effort pulling it all together," Williams said. "Liz Luu from the UC Davis Honey and Pollination Center (HRC) was in a word, fantastic, keeping every thing and everyone together. The HPC really showed what it can do and what tremendous value it adds to our campus. The organizing committee worked so well together, sharing the load throughout. A great set of colleagues!"

The next International Pollinator Conference will take place at Pennsylvania State University.  Grozinger and Rufus Isaacs of Michigan State University launched the conference in 2012. They are held every third year.

"Extreme Bees in Extreme Environments: Bee Biogeography in the Atacama Desert."

That's the title of a seminar tomorrow (Wednesday, May 29) by Laurence Packer, distinguished research professor in the Department of Biology, York University.

His seminar, hosted by the UC Davis Department of Entomology and Nematology, begins at 4:10 p.m. in 122 Briggs Hall, off Kleiber Hall Drive. A large crowd is expected.

If you're not familiar with the Atacama Desert, it's a desert plateau in Chile. It's basically a strip of land along the Pacific coast, west of the Andes Mountains.

Rain? That's a rarity.

"Evidence suggests that the Atacama may not have had any significant rainfall from 1570 to 1971," according to Wikipedia. "The desert owes its extreme aridity to a constant temperature inversion due to the cool north-flowing Humboldt ocean current, and to the presence of the strong Pacific anticyclone. The most arid region of the Atacama desert is situated between two mountain chains (the Andes and the Chilean Coast Range) of sufficient height to prevent moisture advection from either the Pacific or the Atlantic Oceans, a two-sided rain shadow."

In his abstract, Packer says: "The Atacama desert is the driest desert in the world and one of the oldest. In the extreme north of Chile, there is a disjunction between the winter rainfall area to the southwest and summer rainfall to the northeast. In this presentation I will explore the role of the origin of the Andes, the separation between Atacama and Patagonian deserts and the origin of the winter-summer rainfall disjunction on bee diversification. I will also compare the evolutionary origins of several groups of bees and their adaptations to their preferred genus of floral hosts – Nolana – which is the most speciose genus of plants in this arid environment."

Packer describes himself as a melittologist--"someone whose main academic passion is the study of wild bees. This means someone who studies bees other than the domesticated honey bees.

"It's not that I do not like Apis mellifera," he clarifies on his website. "It's just that it is only one out of over 20,000 described bee species. "Few people pay attention to the 20,214 (Discover Life as of Jan. 13, 2017) other bee species, whereas there are whole societies dedicated to the study and culturing of this one. When people find out that I study bees, invariably the next thing they say concerns the honey bee. I will then point out that asking me a question about Apis mellifera is like asking an ornithologist a question about chickens."

If fact, Packer told an ornithologist at an international biodiversity meeting sponsored by the Food and Agriculture Organization of the United Nations: "If all birds dropped dead tomorrow, only chicken farmers and academic ornithologists would be inconvenienced. If all bees died out, there would be worldwide food shortages and perhaps one-quarter of the human population would starve." 

In recalling the conversation and the reaction, he quipped: "I'm very good at making myself popular with people."

Seminar host Leslie Saul-Gershenz, associate director of research, Wild Energy Initiative, John Muir Institute of the Environment, UC Davis (she holds a doctorate in entomology from UC Davis) says "Laurence Packer is a master systematist and specialist on halictid, colletid and really most any bee he encounters in his travels around the world. He is a naturalist-explorer of the some of the most extreme arid regions on the planet.  And he is a superb writer on the plight of native bees in the most entertaining way, I think of him as the Oscar Wilde of entomologists." (See news story.)

A noted author, Packer wrote Keeping the Bees: Why All Bees Are at Risk and What We Can Do to Save Them. Packer, who holds a degree in zoology, with honors, from the University of Oxford (1976), received a postgraduate certificate in education in 1977 from the Christ Church College, Canterbury, and a doctorate in 1986 from the University of Toronto. He joined the faculty of York University in 1999. For eight years, he served as one of seven instructors for The Bee Course,  an international workshop sponsored by the American Museum of Natural History's Southwestern Research Station.  (Robbin Thorp, UC Davis distinguished emeritus professor, was also one of the veteran instructors.)

The Wednesday seminar is the second to last one of the spring quarter. Immo Hansen of New Mexico State University will speak on "Toward Implementation of Mosquito Sterile Insect Technique" at 4:10 p.m., Wednesday, June 5 in 122 Briggs. Seminar coordinator is medical entomologist Geoffrey Attardo, assistant professor, UC Davis Department of Entomology and Nematology. He may be reached at at gmattardo@ucdavis.edu.