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.
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?
The narrowleafed milkweed, Asclepias fascicularis, beckons monarch butterflies (the host plant), aphids, praying mantids and assorted other insects, but once in a while, you'll see a leafcutter bee. Both the plant and the bee are natives.
This male bee (below) spent the afternoon patrolling for females, but it rested in between.
It's a dangerous place to rest when there's a predator (praying mantis) around, but all ended well.
Leafcutter bees, spp., so named because the females cut leaves and petals (perfectly round holes!) to line their nests, are smaller than honey bees--and much faster. They're 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.
The male's job is to reproduce. And sometimes, you'll see one sunning itself on a milkweed leaf.
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,/span>
Hey, the sun's up! It's time to rise and shine! Maybe I'll shine before I rise...or maybe I'll...
Anyway, I just woke up, and I'm starting to stir. I'm ready to conquer the day. I shall
- Sip nectar
- Seek girlfriend
- Guard the flower patch by dive-bombing and chasing off all critters.
The scenario: a male longhorned bee, Melissodes agilis, has just spent the night sleeping--and quite cozily at that--on a Mexican sunflower, Tithonia rotundifola.
He is Boy Bee With the Green Mesmerizing Eyes.
Boy Bee With the Green Mesmerizing Eyes does not know--nor would he care if he could--that today is the beginning of National Pollinator Week, an international annual event celebrating pollinator health.
According to the Pollinator Partnership, "pollination is a vital stage in the life cycle of all flowering plants. When pollen is moved within a flower or carried from one flower to another of the same species it leads to fertilization. This transfer of pollen is necessary for healthy and productive native and agricultural ecosystems." It's crucial to our ecosystem.
As the Pollinator Partnership says on its website:
- "About 75 percent of all flowering plant species need the help of animals to move their heavy pollen grains from plant to plant for fertilization."
- "About 1,000 of all pollinators are vertebrates such as birds, bats, and small mammals."
- "Most pollinators (about 200,000 species) are beneficial insects such as flies, beetles, wasps, ants, butterflies, moths, and bees."
But back to Boy Bee With the Mesmerizing Green Eyes.
Noted bee expert, the late Robbin Thorp, a UC Davis distinguished emeritus professor of entomology and co-author of California Bees and Blooms: A Guide for Gardeners and Naturalists (Heyday), used to talk about these little guys bullying all the floral tenants--from honey bees to syrphid flies to butterflies to lady beetles--and more.
Boy, do they move fast. A good time to photograph them is when they're sleeping or just waking up. Otherwise, try to capture images of them at a shutter speed of about 1/5000 of a second.
Happy Beginning of National Pollinator Week!
Back in the 2009, a team of University of California scientists, led by Gordon Frankie of UC Berkeley and Robbin Thorp (1933-2019) of UC Davis, wrote this incredible article, "Native Bees are a Rich Natural Resource in Urban California Gardens," published in California Agriculture (UC Agriculture and Natural Resources).
It's an excellent resource.
"Evidence is mounting that pollinators of crop and wildland plants are declining worldwide. Our research group at UC Berkeley and UC Davis conducted a 3-year survey of bee pollinators in seven cities from Northern California to Southern California. Results indicate that many types of urban residential gardens provide floral and nesting resources for the reproduction and survival of bees, especially a diversity of native bees. Habitat gardening for bees, using targeted ornamental plants, can predictably increase bee diversity and abundance, and provide clear pollination benefits."
Jennifer Hernandez, Barbara Ertter, Jaime Pawelek, Sara Witt, Mary Schindler, Rollin Coville, and Victoria Wojcik. Coville provided the images.
"Outdoor urban areas worldwide are known to support a rich diversity of insect life (Frankie and Ehler 1978)," they wrote. "Some insects are undesirable and characterized as pests, such as aphids, snails, earwigs and borers; urban residents are most aware of these. Other urban insects are considered beneficial or aesthetically pleasing, such as ladybird beetles and butterflies; this category includes a rich variety of insects whose roles in gardens go largely unnoticed and are thus underappreciated (Grissell 2001; Tallamy 2009). They regularly visit flowers and pollinate them, an important ecological service."
"We report the results of a 2005-to-2007 survey of bees and their associations with a wide variety of ornamental plant species in seven urban areas, from Northern California to Southern California. While non-native honey bees (Apis mellifera) are common in many gardens, numerous California native bee species also visit urban ornamental flowers. Of about 4,000 bee species known in the entire United States, about 1,600 have been recorded in California."
That deserves to be repeated. Of the 4000 bee species known in the United States, about 1600 reside in California. See some of them listed on the chart above.
Notice it includes the non-native bee, the honey bee, Apis mellfera. It is an "introduced bee," although numerous non-scientists think it's a native. European colonists introduced it to America (in what is now Virginia) in 1622.
The phrase, "Save the (Honey) Bees," became prominent during the colony collapse disorder. But the bees that need saving now are the natives.
If you want to know more about the native bees in California, this book should be in your library: California Bees and Blooms: A Guide for Gardeners and Naturalists by UC-affiliated scientists/span>