- Author: Kathy Keatley Garvey
If you've ever been to Bodega Head in Sonoma County, you may have marveled at the waves crashing and the whales surfacing.
But have you ever seen the digger bees, Anthophora bomboides stanfordiana, aka bumble bee mimics, that nest in the sandstone cliffs?
They're there. They're foraging on flowers, excavating their nests, and rearing young.
These digger bees are not easy to photograph. On our May 9th trip, we got lucky: our 200mm macro lens picked up a digger bee warming its flight muscles.
"The species name indicates that it is a bumble bee mimic," the late Robbin Thorp (1933-2019), a global authority on bumble bees and a UC Davis distinguished emeritus professor of entomology. "These bees need a source of fresh water nearby. Females suck up water, regurgitate it on the sandstone bank surface, then dig away at the soft mud. They use some of the mud to build entrance turrets, presumably to help them locate their nests within the aggregation of nests."
"The female," Thorp said, "sucks up fresh water from nearby, stores it in her crop (like honey bees store nectar) for transport to the nest. She regurgitates it on the sandstone, and excavates the moistened soil. She carries out the mud and makes the entrance turret with it."
Thorp, a 30-year member of the Department of Entomology and Nematology, studied these bees. (See his presentation at the Proceedings of the Symposium on Biodiversity of Northwestern California, Santa Rosa, delivered in October 1991.)
Today, community ecologist and associate professor Rachel Vannette from the same department, is among scientists engaged in the research of these fascinating bees.
- Author: Kathy Keatley Garvey
Head to the Bodega Bay in Sonoma County and you'll see little kids building sandcastles on the beaches.
But head to Bodega Head in the spring and summer, and if you're lucky, you'll see female digger bees—bumble bee mimics—creating their own versions of sandcastles. These bees, Anthophora bomboides stanfordiana, build their nests in the sandy cliffs.
Look for the evidence: nest holes and tiny turrets.
If you missed it, be sure to access KQED's Deep Look video on “This Bee Builds Sandcastles at the Beach” by Gabriela Quirós and crew. It's educational, informative and entertaining. The photography is superb.
An excerpt from the Deep Look video: “It might seem peculiar to see bees at the beach. But the bumblebee-mimic digger bee (Anthophora bomboides stanfordiana) makes its home at beaches in Northern California and Oregon. Once they've mated, the females spend the spring digging their nests into sandy cliffs overlooking the Pacific Ocean.”
“They find a nearby source of water like a stream and slurp water into a pouch in their abdomen called a crop. They can make 80 daily trips back and forth from the stream to a cliff onto which they spray the water to soften it up. This allows them to dig a series of holes into which they lay their eggs.”
This digger bee is sometimes called the “Stanford bumble bee digger,” because the subspecies name, “stanfordiana,” refers to the Stanford University collection from 1904.
What do they mimic? The yellow-faced bumble bee, Bombus vosnesenskii, native to the West Coast of North America. But unlike the female bumble bees, female digger bees rarely sting and are not defensive.
The late Robbin Thorp (1933-2019), distinguished emeritus professor of entomology at UC Davis studied these bees. Current researchers include community ecologist Rachel Vannette, associate professor, UC Davis Department of Entomology and Nematology.
Thorp frequently pointed out that when most people think of bees, they think of honey bees. But there's a great diversity in bees, as he wrote in a paper, “Biodiversity and Pollination Biology of Bees in Coastal Nature Preserves,” that he and colleague Thomas Gordon presented at the Proceedings of the Symposium on Biodiversity of Northwestern California, held Oct. 28-30, 1991 in Santa Rosa. “The world bee fauna of bees (superfamily Apoidea) is estimated at 20,000 species,” they wrote. “Of these, about 10% are social, 75% are solitary, and 15 % are cuckoo parasites of other bees (Bohart, 1970).
“Bees are most diverse and abundant in arid warm temperate areas of the world, especially in the Mediterranean, California, and adjacent desert areas (Michener 1979),” they wrote. “With rare exceptions, bees rely on nectar and pollen as food resources: nectar primarily as energy for flight and other activities, pollen as nutrients for reproduction (ovarian and brood development). Most bees are generalists when foraging for nectar, restricted primarily by body or tongue size. Many bee species, however, exhibit host-specificity (oligolecty) in relation to pollen resources (Robertson, 1925; Linsley, 1958). Linsley and MacSwain (1958) define oligolecty as the collection of pollen from one or a few closely related plant species by all members of a bee species with use of alternative sources occurring only during stress periods when such pollen sources are locally (or temporarily) absent.”
“Bees are ‘keystone' species in most plant communities because of their importance as pollinators for the reproductive continuity of many flowering plants including rare and endangered species,” they related.
We've seen the digger bees at Bodega Bay foraging on wild radish and lupine in the spring and summer. And building sandcastles the ocean waves can't reach and people generally ignore.
Last week we saw a family checking out the holes in the sandy cliffs. “What are these?” they inquired.
“Digger bees, bumble-bee mimics,” I responded, mentioning the KQED “Deep Look” video.
They said they'd watch it.
We have a feeling they'll be back next year to watch the bees build their sandcastles.
- Author: Kathy Keatley Garvey
Two UC Davis Department of Entomology and Nematology faculty members are now full professors, and a third faculty member has achieved tenure as associate professor.
Molecular geneticist and physiologist Joanna Chiu, vice chair of the department, and community ecologist Louie Yang were promoted from associate professors to professors, effective July 1. Community ecologist Rachel Vannette was promoted from assistant professor to associate professor.
Chiu Lab
Professor Chiu joined the Department of Entomology and Nematology in 2010 as an assistant professor and advanced to associate professor and vice chair in 2016. She received her bachelor's degree in biology and music from Mount Holyoke College, Mass., and her doctorate in molecular genetics in 2004 from New York University, New York. She served as a postdoctoral fellow from 2004 to 2010 in chronobiology (biological rhythms and internal clocks)--molecular genetics and biochemistry--at the Center for Advanced Biotechnology and Medicine, at Rutgers, the State University of New Jersey.
Chiu's research expertise includes molecular genetics of biological timing and posttranslational regulation of proteins. She uses animal models including Drosophila melanogaster and mice to study the mechanisms that regulate circadian and seasonal physiology and behavior. Major grants from the National Institutes of Health and the National Science Foundation fund her biological rhythms research. In addition to her research in biological rhythms, Chiu also aims to leverage her expertise in genomics to address key issues in global food security.
In 2019, she was named one of 10 UC Davis Chancellor's Fellows, an honor awarded to associate professors who excel in research and teaching.
Chiu and Yang co-founded and co-direct (with Professor Jay Rosenheim) the campuswide Research Scholars Program in Insect Biology, launched in 2011 to provide undergraduates with a closely mentored research experience in biology. The program crosses numerous biological fields, including population biology; behavior and ecology; biodiversity and evolutionary ecology; agroecology; genetics and molecular biology; biochemistry and physiology; entomology; and cell biology. The goal is to provide academically strong and highly motivated undergraduates with a multi-year research experience that cultivates skills that will prepare them for a career in biological research.
Yang Lab
Professor Yang, who holds a bachelor's degree (ecology and evolution) from Cornell University, 1999, received his doctorate from UC Davis in 2006, and joined the UC Davis faculty in 2009. In 2013, he received a prestigious National Science Foundation Faculty Early Career Development Award of $600,000. He was named a UC Davis Hellman Fellow in 2012; the Hellman Family Foundation contributes funds to support and encourage the research of promising assistant professors who exhibit potential for great distinction in their research. He was promoted to associate professor in 2015.
Yang won the 2018 Outstanding Faculty Academic Advising Award from NACADA, also known as the Global Community for Academic Advising; and the 2017 Faculty Advisor Award of Excellence in NACADA's Pacific Region 9, comprised of California, Nevada and Hawaii.
Yang says of the research underway in his lab: “We study how species interactions change over time. We apply a diversity of approaches and perspectives to a diversity of systems and questions. We do experimental community ecology. We also use observational methods, meta-analysis, conceptual synthesis, ecosystem perspectives, and theoretical models. We like data, and we like learning new things.”
Vannette Lab
Associate Professor Vannette joined the UC Davis Department of Entomology and Nematology in 2015 after serving as a postdoctoral fellow at Stanford University's biology department, where she was a Gordon and Betty Moore Foundation Postdoctoral Fellow from 2011 to 2015 and examined the role of nectar chemistry in community assembly of yeasts and plant-pollinator interactions.
Vannette received her bachelor of science degree, summa cum laude, in 2006 from Calvin College, Grand Rapids,Mich., and her doctorate from the University of Michigan's Department of Ecology and Evolutionary Biology, Ann Arbor, in 2011. She received a Hellman Fellowship grant in 2018 and a National Science Foundation Faculty Early Career Development Award in 2019 to study microbial communities in flowers and a National Science Foundation grant to support work on solitary bee microbiomes.
Of her research, Vannette says: “ All plants are colonized by microorganisms that influence plant traits and interactions with other species, including insects that consume or pollinate plants. I am interested in the basic and applied aspects of microbial contributions to the interaction between plants and insects. I also use these systems to answer basic ecological questions, such as what mechanisms influence plant biodiversity and trait evolution.”
“The Vannette lab is a team of entomologists, microbiologists, chemical ecologists, and community ecologists trying to understand how microbial communities affect plants and insects (sometimes other organisms, too),” she says. “We often study microbial communities in flowers, on insects or in soil. We rely on natural history observations, and use techniques from chemical ecology, microbial ecology and community ecology. In some cases, we study applied problems with an immediate application including pathogen control or how to support pollinators. Other questions may not have an immediate application but are nonetheless grounded in theory and will contribute to basic knowledge and conservation (e.g. how can dispersal differences among organisms affect patterns of abundance or biodiversity?)”
- Author: Kathy Keatley Garvey
There's more to Sonoma County's Bodega Head than the stunning views, crashing waves, nesting seabirds, and bursts of flora and fauna.
The sand cliffs are also the home of a digger bee, a bumble bee mimic known as Anthophora bomboides stanfordiana.
"The species name indicates that it is a bumble bee mimic," the late Robbin Thorp, a global authority on bumble bees and a UC Davis distinguished emeritus professor of entomology, told us several years ago. "These bees need a source of fresh water nearby. Females suck up water, regurgitate it on the sandstone bank surface, then dig away at the soft mud. They use some of the mud to build entrance turrets, presumably to help them locate their nests within the aggregation of nests."
"The female," Thorp said, "sucks up fresh water from nearby, stores it in her crop (like honey bees store nectar) for transport to the nest. She regurgitates it on the sandstone, and excavates the moistened soil. She carries out the mud and makes the entrance turret with it."
On multiple trips to Bodega Bay over the years, we watch in fascination as the bees excavate their homes, zip in and out of their turrets, and nectar on nearby flowers.
This time (June 24) we photographed an ant and bee encounter on a turret. The ant? Formica transmontanis, according to ant specialists Phil Ward, professor of entomology at UC Davis, and UC Davis alumnus Brendon Boudinot, who recently received his doctorate from UC Davis, studying with Ward.
"The species nests on the bluffs," Ward told us.
And about that bee-ant encounter? Commented Boudinot: "I suspect the little lady was alarmed by the big bee. These ants and their relatives are rather passive scavengers except during the brooding season, when fresh meat is an order. Most entomeat for Formica tend to be free-walking insects than barricaded larvae, as probably for the bee. For these reasons I think that the encounter may be coincidental!"
Scores of UC Davis entomologists have engaged in research at Bodega Bay. Rachel Vannette, assistant professor, UC Davis Department of Entomology and Nematology, is currently researching Anthophora bomboides stanfordiana and its nests as part of a National Science Foundation grant. Her project on solitary bee provision microbiome includes investigating the diverse community of bacteria and fungi in the provisions and brood cells.
While COVID-19 mandates and precautions hamper her research team's efforts (she's done some preliminary sampling this year and the entire team is planning to do research next year), the digger bees of Bodega Head keep digging, crafting turrets, nectaring on the nearby flora--and encountering ants.
They're all in this together.
- Author: Ben Faber
What a lot of bees. These are Miner or Chimney bee nests. Another type of Digger bee, these nests are from Santa Paula Canyon thanks to Nathan Lurie
The hills are alive with the sound of BEE-EEZZE. And often they are found crawling on the ground, as is the case of Digger Bees. At this time of year, they might be seen along the margins of avocado orchards, near hiking trails or in undisturbed areas of citrus orchards. They are called Digger Bees commonly, but this is just a generic name for a large group of bees that nest in the ground. There are many genera and species and because of the general lack of study of these bees they are lumped under the name Digger for lack of any greater knowledge and naming of them.
There are several kinds of small hairy or metallic bees that dig into the soil to nest, hence the common name, digger bees. They are a diverse group that comes from different families and the term digger bee can include the andrenid bees, halictid bees, and colletid bees such as the plasterer and yellow-faced bees. These are solitary bees and native pollinators that are active early in the season. Each female digs a cylindrical underground tunnel as a nest where she reproduces (as opposed to social bees such as honey bees where only the queen reproduces and maintains a colony with the help of sterile workers). Although solitary, they form colonies that may have several hundred nests in one spot, but all nests are independently owned.
The subterranean nest is provisioned with a mixture of nectar and pollen collected from nearby flowering plants. This "bee-bread" is food for the bee's offspring (larvae) that develop in the underground chamber and emerge as adults the following year.
Digger bees are 1/4 to 1/2-inch-long and variable in color (mostly shiny metallic or dark, but some with markings of white, yellow or reddish brown). There is one generation of digger bees per summer and once the adults finish perpetuating the species by laying eggs of the next generation there will be no activity till the following spring.
Digger bee nests are commonly located in areas where grass and mulch are scarse, either from too much shade, previous drought conditions or other stress. Most of them like to fly around their airspace at different times of the day, something to do with mating, air temperature or staking territory. They often travel great distances to forage.
The threat of being stung by digger bees is unlikely. The bees are docile and not likely to sting unless handled or threatened. There is no nest guarding behavior or attack behavior like there is with social insects such as honey bees and yellowjacket wasps.
Another recent colony find was comprised of another digger bee.
In the case of this bee find, they are possibly Diadasia bituberculata – as suggested by Robin Thorpe, UCD entomologist. They are uncommon in the rest of the world, but found here in California and the western US. There are over 1,000 digger bee species.
Diadasia Digger Bee "Colony", Thanks to Pest Control Adviser Jane Delahoyde's friend.