- Author: Kathy Keatley Garvey
It's nicknamed "the sunflower bee" for good reason.
It forages on sunflowers.
We recently spotted a longhorned bee, Svastra obliqua, also called "the sunflower bee," on Gaillardia, aka blanket flower, a member of the sunflower family, Asteracease.
Asteraceae is comprised of more than 32,000 known species of flowering plants. And Svastra? Fourteen different species occur in North America and seven in California, according to the UC Berkeley Urban Bee Lab, which provides this description:
"Overall they are medium to large, with stout bodies, gray hair on their thorax, and irregular striping on their abdomen. Females can be distinguished by their scopae, which are located on their hind legs. They additionally are larger compared to males and have dark faces. Males have yellow markings on the bottom section of their faces and are typically more elongate in body size. Both male and female bees have long antennae. Svastra sp. look very similar to Melissodes without using a microscope. However, Svastra sp. will have longer antennae than both Anthophora and Diadasia so the difference is more noticeable."
Those long antennae...those eyes...those mesmerizing eyes...
You can read more about California's native bees in California Bees and Blooms: a Guide for Gardeners and Naturalists, a book authored by the University of California team of Gordon Frankie, Robbin Thorp, Rollin Coville and Barbara Ertter. All are affiliated with UC Berkeley. Thorp, who received his doctorate in entomology from UC Berkeley, was a member of the UC Davis entomology faculty for 30 years, from 1964-1994. He achieved emeritus status in 1994 but continued his research, teaching and public service until a few weeks before his death on June 7, 2019.
![Svastra obliqua, Svastra obliqua,](/blogs/blogcore/blogfiles/108197.jpg)
- Author: Kathy Keatley Garvey
In the sweltering heat of Solano County (100 degrees) during National Pollinator Month, how about an image of a sweat bee, genus Halictus, a tiny bee that's often overlooked in the world of pollinators.
It's a social bee that nests in the soil. "These nests consist of a complex of tunnels with individual brood chambers," according to California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday), the work of UC-affiliated scientists,
My camera caught this Halictus flying over Coreopsis in our Vacaville pollinator garden on June 5.
Camera: Nikon Z8 with a 50mm lens
Settings: Shutter speed, 1/4000 of a second; f-stop, 5; ISO 500.
UC Davis distinguished professor emerita Lynn Kimsey, emeritus director of the Bohart Museum of Entomology, and Bohart Museum scientist Sandy Shanks said the species appears to be Halictus ligatus.
Most Halictus species are generalist foragers, according to the Great Sunflower Project. "They use all sorts of genera of plants from the Asteraceae to Scrophulariaceae. They are very common on composites (daisy-like disc and ray flowers) in summer and fall."
We've seen them on everything from mustard to milkweeds to catmint to rock purslane, from spring to fall. They also appear regularly on the tower of jewels (Echium wildpretii).
Not to mention the Coreopsis.
/span>![A sweat bee, genus Halictus, sailing over a Coreopsis in a Vacaville pollinator garden. June is National Pollinator Month. (Photo by Kathy Keatley Garvey) A sweat bee, genus Halictus, sailing over a Coreopsis in a Vacaville pollinator garden. June is National Pollinator Month. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/107169.jpg)
- Author: Kathy Keatley Garvey
Hello there, little leafcutter bee! Yes, you, foraging on the sky-blue Chinese Forget-Me-Nots!
You're just in time for National Pollinator Week!
Leafcutter bees, family Megachilidae, are so named because the females cut leaves and petals (perfectly round holes!) to line their nests. Smaller than honey bees--and much faster, leafcutter bees are easily recognizable by the black-white bands on their abdomen.
The females do all the work. They gather pollen and nectar, make the nests from the leaf and petal fragments, and lay eggs. They seal the egg chambers with the leaves or flower petals.
In our pollinator garden, leafcutter bees are quite fond of Chinese Forget-Me-Nots, Cynoglossum amabile. "Many wild bees prefer flowers in the violet-blue range—in part because these blossoms tend to produce high volumes of nectar," according to an Oct. 18, 2017 article in Science.org.
Of the 4000 bee species known in the United States, about 1600 reside in California. The leafcutter bee is just one of them. The family, Megachilidae, includes these leafcutting bees:Megachile angelarum, M. fidelis and M. montivaga; the alfalfa leafcutting bee, M. rotundata; the Mason bee, Osmia coloradensis; and the blue orchard bee (BOB), Osmia lignaria propinqua.
For more information on California's bees, read California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday), the work of UC-affiliated scientists,
Thorp, a global and legendary authority on bees and a distinguished emeritus professor of entomology at UC Davis, died June 7, 2019 at his home in Davis. He was 85.
/span>![A leafcutter bee, family Megachilidae, peers at the photographer. A leafcutter bee, family Megachilidae, peers at the photographer.](/blogs/blogcore/blogfiles/100132.jpg)
![The leafcutter bee continues foraging on the Chinese-Forget-Me-Nots. (Photo by Kathy Keatley Garvey) The leafcutter bee continues foraging on the Chinese-Forget-Me-Nots. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/100133.jpg)
![Yes, this spot here looks good! The leafcutter bee ignores the photographer. (Photo by Kathy Keatley Garvey) Yes, this spot here looks good! The leafcutter bee ignores the photographer. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/100134.jpg)
![](/blogs/blogcore/blogfiles/100135.jpg)
- Author: Kathy Keatley Garvey
Stuligross, who received her doctorate in ecology on Sept. 9 from UC Davis, will present her exit seminar, "Individual and Combined Effects of Resource and Pesticide Stressors on Wild Bees and a Potential Strategy to Mitigate Impacts" at 10 a.m., Tuesday, Oct. 18 in Room 1022 of Green Hall.
The seminar, open to all interested persons, also will be virtual. The Zoom link is https://ucdavis.zoom.us/j/3661107142.
Stuligross researches nutrition and pesticide exposure and their comparative effects on the blue orchard bee, Osmia lignaria, and the yellow-faced bumble bee, Bombus vosnesenskii. Pollination ecologist Neal Williams, professor in the Department of Entomology and Nematology, served as her major professor.
"I am doing a short postdoc with Neal Williams this fall, and in January I will start a postdoctoral research position with Nicole Rafferty at UC Riverside," Stuligross said.
"Anthropogenic environmental changes present multiple stressors that together impact biodiversity and ecosystem function," Stuligross writes in her abstract. "Among these, pesticide exposure and the loss of flowering plants are ubiquitous across contemporary landscapes and threaten the persistence of bee populations. In this dissertation, I explored the individual and combined effects of pesticide and floral resource stressors on bee behavior, reproduction, and population persistence, as well as a potential strategy for mitigating these impacts. I used a combination of manipulative field cage experiments and landscape studies to examine these stressors and their impacts at different scales.
"Because bees often experience pesticide and resource stressors simultaneously, I first examined the potential for interactive effects of these stressors, as well as their individual impacts on wild bees. I established a fully crossed design in field cages; nesting female Osmia lignaria, the solitary blue orchard bee, accessed wildflowers at high or low densities, treated with or without the common insecticide, imidacloprid. In Chapter 1, I showed that pesticide exposure and floral resource scarcity combined additively to dramatically alter multiple vital rates, including reduced reproduction and a male-biased offspring sex ratio. In Chapter 2, I quantified behavioral responses in the same experiment, revealing that the resource and pesticide stressors had differential impacts with consequences for bee populations and potentially for pollination services through individual behavioral changes. Limited floral resources required bees to make fewer, longer foraging trips as well as misidentify their nests more often upon return from these trips. Bees exposed to pesticides made shorter foraging trips and did not compensate for this by taking more trips, reducing their overall foraging activity. Pesticide exposure also interacted with age to affect antagonistic behavior."
"In Chapter 3, I examined the carryover effects of past pesticide exposure on wild bees. Using the offspring from the previous cage experiment with known pesticide exposure backgrounds, I re-established the field cages and released bees in a crossed design with pesticide exposure or no exposure in each year. Thus, some bees experienced pesticides over two generations and others not at all. Regardless of the past exposure history, pesticides in the second year reduced reproduction. For bees that were also exposed in the past, the exposure over two years additively impaired individual performance, leading to a nearly fourfold estimated reduction in bee population growth. Furthermore, even past exposure by itself, regardless of exposure in the second year, led to a decline in offspring production."
"In Chapter 4, I collaborated with Maj Rundlöf to investigate the potential for wildflower plantings to mitigate the negative effects of pesticide exposure in agricultural landscapes. We assessed the nesting and reproduction of O. lignaria and the bumble bee Bombus vosnesenskii in replicate agricultural landscapes, half of which contained a wildflower planting next to the nest or colony. We collected pollen from foraging bees to determine resource use and pesticide residues. The wildflower plantings were a source of pesticide exposure, especially for O. lignaria, but also supported O. lignaria nesting. The landscape-level floral resources better predicted B. vosnesenskii colony success, but the local flower resources mitigated the negative effects of pesticides on their reproduction."
"These chapters together show that two common environmental stressors combine to negativel impact bees. They also reveal potential mechanisms underlying impacts of the stressors on reproduction and population growth. My dissertation highlights the importance of mitigating the negative effects of pesticides and floral resource limitation, especially in agricultural landscapes where the two stressors often co-occur. Finally, this work offers insight into how the stressors could be mitigated through an emerging strategy to diversity agricultural landscapes."
Stuligross received her bachelor of arts degree in environmental studies in 2014 in Indiana from Earlham College, Richmond, where she minored in biology and outdoor education. At UC Davis, she was awarded a 2017-22 National Science Foundation Graduate Research Fellowship, and a 2016-18 UC Davis Graduate Group in Ecology Fellowship.
Recognized nationally for her research, Stuligross scored second place in the Entomological Society of America's 2020 President's Prize competition. Her research posters also won the top award at the UC Davis Graduate Student Symposium in Ecology in both 2019 and 2021.
Stuligross and her colleague, Maj Rundlöf, are the co-first authors of "Flower Plantings Support Wild Bee Reproduction and May Also Mitigate Pesticide Exposure Effects," published in May 2022 in the Journal of Applied Ecology. She was the lead author of "Past Insecticide Exposure Reduces Bee Reproduction and Population Growth Rate," published in November 2021 in the Proceedings of the National Academy of Sciences, and also the lead author of "Pesticide and Resource Stressors Sdditively Impair Wild Bee Reproduction," published in September 2020 in The Proceedings of the Royal Society B.
Stuligross has also co-authored a number of other research publications, most recently:
- "A Meta-Analysis of Single Visit Pollination Effectiveness Comparing Honeybees and Other Floral Visitors," American Journal of Botany
- "Impact of 'Nonlethal' Tarsal Clipping on Bumble Bees (Bombus vosnesenskii) May Depend on Queen Stage and Worker Size," Journal of Insect Conservation
Want to learn more about wild bees, also known as undomesticated bees? Be sure to read the UC-authored book, California Bees and Blooms: A Guide for Gardeners and Naturalists. It's the work of Gordon Frankie of UC Berkeley, the late Robbin Thorp of the UC Davis Department of Entomology and Nematology; Barbara Ertter of UC Berkeley; and photographer Rollin Coville, alumnus of UC Berkeley. California is home to more than 1600 species of undomesticated or wild bees.
![A blue orchard bee, Osmia lignaria, heads toward Phalacia. (Photo by Clara Stuligross) A blue orchard bee, Osmia lignaria, heads toward Phalacia. (Photo by Clara Stuligross)](/blogs/blogcore/blogfiles/95519.jpg)
![A yellow-faced bumble bee, Bombus vosnesenskii, heads toward a California golden poppy. Both are natives. (Photo by Kathy Keatley Garvey) A yellow-faced bumble bee, Bombus vosnesenskii, heads toward a California golden poppy. Both are natives. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/95521.jpg)
- Author: Kathy Keatley Garvey
Honey bees absolutely love African blue basil. If there ever were a "bee magnet," this plant is it.
We first learned of African blue basil, (Ocimum kilimandscharicum × basilicum 'Dark Opal'), through Gordon Frankie, UC Berkeley professor and the late Robbin Thorp, distinguished emeritus professor of entomology at UC Davis. They co-authored the book, California Bees and Blooms: a Guide for Gardeners and Naturalists with Rollin Coville and Barbara Ertter, also affiliated with UC Berkeley.
We plant it every year in our pollinator garden. Wikipedia calls African blue basil "a cross between camphor basil and dark opal basil. "African blue basil plants are sterile, unable to produce seeds of their own, and can only be propagated by cuttings.
"All parts of the flower, leaves and stems are edible; although some might find the camphor scent too strong for use in the kitchen, the herb reportedly yields a tasty pesto with a 'rich, mellow flavor' and can be used as a seasoning in soups and salads, particularly those featuring tomato, green beans, chicken, etc.," Wikipedia tells us. "The leaves of African blue basil start out purple when young, only growing green as the given leaf grows to its full size, and even then retaining purple veins. Based on other purple basils, the color is from anthocyanins, especially cyanidin-3-(di-p-coumarylglucoside)-5-glucoside, but also other cyanidin-based and peonidin-based compounds."
A final note that Wikipedia relates: It "blooms profusely like an annual, but being sterile can never go to seed. It is also taller than many basil cultivars. These blooms are very good at attracting bees and other pollinators."
Right. "These blooms are very good at attracting bees and other pollinators."
Wikipedia forgot to mention that blooms are "very good at attracting predators," like praying mantids. They go where the bees are, and the bees are in the African blue basil.
Can you find the mantis in the image below?
![In this image, you can see two bees on the African blue basil. But can you find the praying mantis? (Photo by Kathy Keatley Garvey) In this image, you can see two bees on the African blue basil. But can you find the praying mantis? (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/94298.jpg)
![Oh, there you are, praying mantis! Enjoying a little sunshine, hmm? This one is a male subadult male Stagmomantis limbata, as identified by mantis expert Lohit Garikipati, a UC Davis alumnus now studying for his master's degree at Towson (Maryland) University. (Photo by Kathy Keatley Garvey) Oh, there you are, praying mantis! Enjoying a little sunshine, hmm? This one is a male subadult male Stagmomantis limbata, as identified by mantis expert Lohit Garikipati, a UC Davis alumnus now studying for his master's degree at Towson (Maryland) University. (Photo by Kathy Keatley Garvey)](/blogs/blogcore/blogfiles/94299.jpg)