In a first-of-its-kind study, UC Davis research shows that the double punch of pesticide exposure and food scarcity drastically affects the reproduction of the blue orchard bee, Osmia lignaria, a wild bee known for pollinating early spring bloom, including almonds. 

Lead author and doctoral student Clara Stuligross teamed with her major professor, pollination ecologist Neal Williams of the UC Davis Department of Entomology and Nematology, to publish Pesticide and Resource Stressors Additively Impair Wild Bee Reproduction, in the journal Proceedings of the Royal Society B. 

They exposed the bees to the neonicotinoid insecticide imidacloprid, widely used in agriculture, and found that the combined threats—imidacloprid exposure and the loss of flowering plants—reduced the bee's reproduction by 57 percent, resulting in fewer female offspring. 

Of the two stressors—food scarcity and pesticide exposure—pesticide exposure showed the great impact on nesting activity and the number of offspring produced, they said. 

Other scientists have conducted similar research on honey bees, but this is the first comparable research on wild bees in field or semi-field conditions. 

The blue orchard bee, nicknamed BOB, is a dark metallic mason bee, smaller than a honey bee. It is prized for pollinating almond, apple, plum, pear, and peach trees. California almond growers often set up bee boxes or "bee condos" for blue orchard bees to aid in honey bee pollination. In the wild, the bees nest in reeds or natural holes. 

“Bees and other beneficial insects experience multiple stressors within agricultural landscapes that act together to impact their health and diminish their ability to deliver the ecosystem services on which human food supplies depend,” Stuligross and Williams wrote in their abstract. “Disentangling the effects of coupled stressors is a primary challenge for understanding how to promote their populations and ensure robust pollination and other ecosystem services.” 

To study the survival, nesting and reproduction of the blue orchard bee, they set up nesting females in large flight cages, some with high densities of wildflowers and others with low densities that were treated “with or without the common insecticide, imidacloprid.” Bees are commonly exposed to insecticides when they forage on treated flowers. 

“Pesticides and resource limitation acted additively to dramatically reduce reproduction in free-flying bees,” they wrote in their abstract. “Our results emphasize the importance of considering multiple drivers to inform population persistence, management, and risk assessment for the long-term sustainability of food production and natural ecosystems.” 

"Understanding how multiple stressors interplay is really important, especially for bee populations in agricultural systems, where wild bees are commonly exposed to pesticides and food can be scarce,” said Stuligross, who holds a bachelor of arts degree in environmental studies (2014) from Earlham College, Richmond, Ind. She joined the UC Davis doctoral program in 2016.

Key factors in affecting bee reproduction are the probability that females will nest and the total number of offspring they have. The UC Davis research found that pesticide-exposed and resource-deprived female bees delayed the onset of nesting by 3.6 days and spent five fewer days nesting than unexposed bees.

Professor Williams pointed out that this is a substantial delay because bees nest only for a few weeks, and it's crucial to reproduce female offspring to carry on the future generations. “Fewer females will reduce the reproductive potential of subsequent generations," said Williams, a UC Davis Chancellor's Fellow and a newly elected fellow of the California Academy of Sciences.

They found that only 62 percent of pesticide-exposed bees produced at least one daughter compared to 92 percent of bees not exposed to pesticides.

The research, accomplished in the spring of 2018 on the grounds of the Harry H. Laidlaw Jr. Facility west of the campus,  drew support from a UC Davis Jastro Research Award, a UC Davis Ecology Graduate Research Fellowship, a National Science Foundation Graduate Research Fellowship, and the UC Davis bee biology facility

The blue orchard bee bee is one of the few native pollinators that is managed in agriculture. North America has 140 species of Osmia, according to a Pollinator Partnership (PP) article in a U. S. Forest Service publication, authored by entomologist and PP member Beatriz Moisset and PP director Vicki Wojcik. “Mason bees use clay to make partitions and to seal the entrance,” they wrote. “This unique mud-building behavior leads to their common designation as mason bees. Honey bees are very important to commercial agriculture, but native bees like the blue orchard bees are better and more efficient pollinators of native crops.”

Imidacloprid, a systemic insecticide that acts as an insect neurotoxin, is used to control sucking insects, termites, some soil insects and fleas on pets, according to National Pesticide Information Center. It mimics nicotine, toxic to insects, which is naturally found in many plants, including tobacco.  More than 400 products for sale in the United States contain imidacloprid. 

A unique UC Davis symposium on "Saving a Bug's Life: Legal Solutions to Combat Insect Biodiversity Decline and the Sixth Mass Extinction" will bring together law and science to address insect biodiversity decline.

The event, sponsored by UC Davis Environmental Law Society (ELS) and scheduled from 8:30 to 6:30 p.m., Friday, March 6 in Room 1001 of the School of Law, 400 Mrak Ave., is free and open to the public. It will include lunch and an evening cocktail reception. Registration is under way on this Facebook page.

Four UC Davis entomologists will be among the speakers. They are:

• Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology, UC Davis Department of Entomology and Nematology, whose expertise includes wasps. Kimsey is the "go-to" person in the department when the public requests general insect information.
• Neal Williams, professor and pollination ecologist, UC Davis Department of Entomology and Nematology, who focuses on native bees.
• Art Shapiro, distinguished professor of evolution and ecology, who has been monitoring the butterfly population of central California since 1972; and
• Brendon Boudinot, doctoral candidate and ant specialist, Phil Ward lab, UC Davis Department of Entomology and Nematology.

Neal Williams, professor of entomology (Photo by Kathy Keatley Garvey)

Insects have been called "the level pullers of the world." One study estimates that insects contribute more than $57 billion a year to the U.S. economy. However, many species currently face extinction.

Experts in the field of entomology and agricultural sciences will converse with leaders in government, legal scholars and practitioners about the current threat to insect populations "and how we can use legal tools, policy and management practices to combat the sixth mass extinction," according to co-chairs Kelly Beskin (kvbeskin@ucdavis.ed) and Peter Jansen (pcjansen@ucdavis.edu).

Four separate panels will center on protecting insects and biodiversity. Some of the major topics will be about "listing insects under the Endangered Species Act and the tensions within agriculture between the need for pollinators and pesticide use," Beskin said.

The California Fish and Game Commission voted 3-1 on June 12, 2019 to place these four bumble bees on the proposed endangered species list, as petitioned by the Xerces Society, Center for Food Safety, and Defenders of Wildlife.

• Franklin's bumble bee, Bombus franklini
• Suckley cuckoo bumble bee, Bombus suckleyi
• Western bumble bee, Bombus occidentalis
• Crotch bumble bee, Bombus crotchi

An insect fair will take place during lunch time. The Bohart Museum of Entomology will showcase insect specimens as well as a live "petting zoo," including Madagascar hissing cockroaches, walking sticks, and tarantulas. Graduate students will display their research projects, and the Entomology Graduate Student Association will be offering insect-themed t-shirts for sale. Cricket protein bars will be handed out to all those interested.  Also planned is honey tasting from the UC Davis Honey and Pollination Center.

"It should be a lot of fun for everybody," Beskin said.

Sponsors, in addition to ELS, include the California Environmental Law and Policy Center;  UC Davis John Muir Institute of the Environment and the UC Davis School of Law.

See agenda on the Facebook page.

Ever seen a bumble bee nest?

We remember when insect enthusiast Rita LeRoy of the Loma Vista Farm, part of the Vallejo City Unified School District, found the nest of the yellow-faced bumble bee, Bombus vosnesenkii, in May of 2015. They were buzzing in and out, providing nectar and pollen for the growing colony.

However, as we all know, overwintering bumble bee nests are even more difficult to find. The queen is hibernating, getting ready to emerge next spring to start a new colony.

And now comes newly published research led by the Neal Williams lab, UC Davis Department of Entomology and Nematology, on Fantastic Bees and Where to Find Them: Locating the Cryptic Overwintering Queens of a Western Bumble Bee.

Published Nov. 20, 2019 in Ecosphere, an open access journal of the Entomolgoical Society of America, it is drawing the attention it should.

The abstract:

"Bumble bees are among the best‐studied bee groups worldwide, yet surprisingly we know almost nothing about their overwintering habitats nor the microsite characteristics that govern selection of these sites. This gap represents a critical barrier for their conservation, especially if preferred overwintering habitats differ from foraging and nesting habitats. Current conservation plans focus on foraging habitat, potentially creating a problem of partial habitats where improved forage might fail to prevent population declines due to limited overwintering sites. We provide the first data on the overwintering habitat for any western North American bumble bee. Our data suggest that overwintering and foraging habitats are likely distinct, and queens' selection of overwintering sites may be shaped by environmental stressors of the year. In our study area, queens overwintered in litter beneath cypress trees, where no floral resources exist. Whether this separation of overwintering and foraging habitat holds for other bumble bee species remains to be discovered. Our data highlight the need to consider the whole life cycle for understanding population dynamics and conservation planning. This need is underscored by growing evidence for the decline of multiple North American bumble bee species."

They detailed how they "looked for overwintering queens on California's central coast. We spent ~80 person‐hours searching different ground covers around abandoned military barracks at former Fort Ord Military Base where we previously observed large numbers of nest‐searching queen Bombus vosnesenskii Radoszkowski and B. melanopygus Nylander."

"Ground cover at Fort Ord is typical of the central California coast: a patchwork of grassy meadow, mats of non‐native ice plant (Carpobrotus edulis), and small stands of Monterey cypress (Cupressus macrocarpa) and Monterey pine (Pinus radiata). In December 2018, we searched for bumble bee queens by carefully digging the vegetative, litter, and soil strata of grassy meadow, ice plant mat, and the needle litter under two cypress and two pine tree."

What did they find and learn? It's well worth the read: https://doi.org/10.1002/ecs2.2949

The highly respected California Academy of Sciences greeted its 2019 Class of Fellows on Oct. 15, and one of them is a pollination ecologist from the University of California, Davis. 

Professor Neal Williams of the UC Davis Department of Entomology and Nematology was inducted into the scientific organization at the annual Bay Area gathering of the Fellows. The group includes more than 450 distinguished scientists who have made notable contributions to science.

Dermatologist and associate professor Emanual Michael Maverakis of UC Davis Health was among the 13 other Fellows. (See list of 2019 inductees)

Fellows nominate others for the high honor, and then the California Academy of Sciences' Board of Trustees votes on the nominees. James R. Carey, distinguished professor of entomology, nominated Williams, with Claire Kremen of the University of British Columbia, formerly of UC Berkeley, seconding the nomination. Maverakis was nominated by Walter Leal, distinguished professor, UC Davis Department of Molecular and Cellular Biology, and a former chair of the entomology department.

In his letter of nomination, Carey wrote that Williams is “widely known and respected for his excellence in research, extension, outreach, teaching and leadership” and “is not only one of the stars of our campus, and the UC system, but is an internationally recognized leader in pollination and bee biology and strong voice in the development of collaborative research on insect ecology. He has organized national and international conferences, leads scores of working groups, and guides reviews of impacts of land use and other global change drivers on insects and the ecosystem services they provide.”

Williams' research spans the ecology and evolution of bees and other pollinating insects and their interactions with flowering plants. “He has become a leading voice for pollinator diversity and conservation in the California and The West,” wrote Carey. “One focus of his work has been in understanding the responses of bees to different environmental drivers and developing practical, scientifically grounded actions to support resilient pollinator communities. These efforts are particularly timely given concern over the global decline in bees and other pollinators.”

The UC Davis professor served as co-chair (with Extension apiclturist Elina Lastro Niño) of the seventh annual International Pollinator Conference, a four-day conference held July 17-20 on the UC Davis campus. The global conference focused on pollinator biology health and policy.

In his work--a labor of love--Williams seeks and finds found common solutions for sustaining both wild and managed bees and communicates that information to the public and stakeholder groups. Said Carey: “This is a critical perspective in natural and agricultural lands, but also in urban landscapes in northern and southern California.”

Each year the UC Davis professor speaks to multiple beekeeper, farmer and gardener groups, and provides guidance to governing bodies, including the state legislature, and environmental groups. He and his lab are involved in a newly initiated California Bombus assessment project, which is using both museum and citizen scientist records to understand past, current and future distributions and habitat use by bumble bees. This program will host a series of workshops this spring and summer open to practitioners and the public.

Williams received his doctorate in ecology and evolution in 1999 from the State University of New York, Stony Brook and served as an assistant professor in the Department of Biology at Bryn Mawr (Penn.) College from 2004 to 2009. He joined the UC Davis faculty in 2009, advancing to full professor in 2017.

His honors and awards are numerous. Williams was part of the UC Davis Bee Team that won the Team Research Award from the Pacific Branch, Entomological Society of America (PBESA) in 2013. In 2015, he was named a five-year Chancellor's Fellow, receiving $25,000 to support his research, teaching and public service activities. And then earlier this year, Williams received PBESA's Plant-Insect Ecosystems Award, presented annually for outstanding accomplishments in the study of insect interrelationships with plants.

In addition to Carey, five others affiliated with UC Davis Department of Entomology and Nematology are Fellows of the California Academy of Sciences:

• Professor Phil Ward, ant specialist
• Frank Zalom, integrated pest management specialist and distinguished professor of entomology. He is a past president of the Entomological Society of America
• Robert E. Page Jr., bee scientist and UC Davis distinguished emeritus professor. He is a former chair of the UC Davis Department of Entomology and provost emeritus of Arizona State University
• Walter Leal, distinguished professor, UC Davis Department of Molecular and Cellular Biology, and a former chair of the entomology department; and
• Visiting scientist Catherine Tauber, formerly of Cornell University.

Former Fellows from the UC Davis entomology department include Robbin Thorp (1933-2019), distinguished emeritus professor of entomology, and visiting scientist Maurice Tauber (1931-2014), formerly of Cornell University.