All will take place on Wednesdays from 4:10 to 5 p.m. in 122 Briggs Hall, Kleiber Hall Drive.
Coordinator Rachel Vannette, assistant professor of entomology, has announced the following:
Sept. 27: “Bug Smell: Evolution of Communication” by Zain Syed of the University of Notre Dame, formerly of the UC Davis Department of Entomology and Nematology
Oct. 4: “Genomic Signatures of Social Evolution in Social Insects” by Tim Linksvayer, University of Pennsylvania
Oct. 11: “Multitrophic Mediation of Plant Perception of Herbivores” by Gary Felton, Pennsylvania State University, who received his doctorate in entomology from UC Davis
Oct. 18: Exit seminar by Leslie Saul-Gershenz, doctoral candidate, UC Davis Department of Entomology and Nematoloy
Oct. 25: To be announced
Nov. 1: “Mating Distruption of Glassy-Winged Sharpshooter by Playback of Natural Vibrational Signals in Vineyard Trellis” by Rodrigo Krugner of the U.S,. Department of Agriculture/Agricultural Research Service (USDA-ARS)
Nov. 8: Exit seminar by doctoral candidate/ecologist Ash Zemenick, UC Davis Department of Entomology and Nematology
Nov. 15: “Revelations from Phasmatodea Digestive Track Transcriptomics” by Matan Shelomi, National Taiwan University, who received his doctorate in entomology from the UC Davis Department of Entomology and Nematology
Nov. 22: Thanksgiving week; no seminar
Nov. 29; “Ant Social Parasites Repeatedly Evolved Reproduction Isolation from Their Hosts in Sympatry” by Christian Rabeling, Arizona State University
Dec. 6: “Root Knot Nematode and Associated Pathogen Resistance” by Phil Roberts, University of Riverside
Cookie will be provided prior to the seminar. For more information on the seminars, contact Vannette at email@example.com or graduate program coordinator Jessica Padilla at firstname.lastname@example.org.
The non-profit educational organization, geared for small-scale beekeepers in the western United States, is headed by president Eric Mussen, Extension apiculturist emeritus, of UC Davis.
WAS has already booked Kim Flottum of Medina, Ohio, editor of Bee Culture; Les Crowder of Austin, Texas, author of Top-Bar Beekeeping; Gene Brandi of Los Banos, president of the American Beekeeping Federation; Larry Connor of Kalamazoo, Mich., author and beekeeper; Rod Scarlett, executive director, Canadian Honey Council, and Slava Strogolov, chief executive officer of Strong Microbials Inc., Milwaukee.
- Extension apiculturist Elina Lastro Niño will speak on “Impact of Varroa on Honey Bee Reproductive Castes): Where Will the Research Lead Us?” at at 8:30 a.m. The three reproductive castes are the queen and worker bee (female), and drone (male).
- Associate professor Brian Johnson will speak on “Geographical Distribution of Africanized Bees in California” at 9 a.m., He will show “the results of a genotyping study of bees caught from across California showing the current distribution of Africanized Honey Bees in our state."
- Distinguished emeritus professor Robbin Thorp, a native pollinator specialist, will discuss “Life Cycles of Commonly Encountered Native Bee Genera" at 10:30 a.m. He is the co-author of Bumble Bees of North America: an Identification Guide and California Bees and Blooms: A Guide for Gardeners and Naturalists.
- Professor Neal Williams, a pollination ecologist, will discuss “Known and Potential of Native Bees in Crop Pollination” at 11 a.m.
Casey also will lead a tour of the haven at 9:30 a.m. on Wednesday, Sept. 6. “The Haven is a unique outdoor museum designed to educate visitors about bees and the plants that support them," she says. "Tour participants will see some of our 85 bee and 200 plant species, learn about our outreach and research programs, and gain ideas for their own bee gardens." Other tours are to Mann Lake facility and Z Specialty Foods, both in Woodland.
On Friday, Sept. 8, Extension apiculturist emeritus Eric Mussen will moderate a panel on “Pesticide Toxicity Testing with Adult and Immature Honey Bees.” The panel will convene at 9:15 a.m. At 1:30 on Friday, assistant professor Rachel Vannette of UC Davis will discuss “Variation in Nectar Quality Influence Pollinator Foraging." She studies floral nectar chemistry and microbiology and examines how these characteristics of flowers mediate interactions between plants and pollinators
Other UC Davis highlights:
Honey Tasting: Amina Harris, director of the Honey and Pollination Center at the Robert Mondavi Institute of Wine and Food Science, UC Davis, will lead a moderated honey tasting at 11 a.m. on Wednesday, Sept. 6. The event is titled “Taste the Honey Flavors of the West: How Understanding the Nuances of your Honey Can Help You Market your Perfect Sweet.” Said Harris: "Basically I plan to discuss the diversity and life styles of non-Apis bees to show how different most are from honey bees."
Memories: The founders of WAS will discuss "how it all began" from 8:45 to 9:30 a.m. on Wednesday, Sept. 6. The organization, founded at UC Davis, was the brainchild of Norm Gary, then professor of apiculture (now emeritus), who served as the first WAS president. Assisting him in founding the organization were Eric Mussen, then an Extension apiculturist who was elected the first WAS vice president; and postdoctoral fellow Becky Westerdahl, now a nematologist in the department, who held the office of secretary-treasurer.
More information on the conference is available from the WAS website or contact Eric Mussen, serving his sixth term as president, at email@example.com. Registration is underway at http://www.westernapiculturalsociety.org/2017-conference-registration/
In newly published research in Ecology Letters, "Dispersal Enchances Beta Diversity in Nectar Microbes," Vannette and colleague Tadashi Fukami of Stanford University's Department of Biology, examined microbial communities inhabiting the nectar of the sticky monkeyflower, Mimulus auranticus, at the Jasper Ridge Biological Preserve in California's Santa Cruz Mountains.
The flower, in the family Phrymacease, is a native shrub common in chaparral and coastal scrub habitats of California and Oregon. It is primarily pollinated by Anna's hummingbird. Other common pollinators include bumble bees, carpenter bees, and thrips.
Dispersal is considered a key driver of beta diversity, which is “the variation in species composition among local communities,” Vannette said.
They are the first to publish work showing that increased dispersal can increase biodiversity.
In their experiment, they reduced natural rates of dispersal by eliminating multiple modes of microbial dispersal. “Specifically we focused in nectar-inhabiting bacteria and yeasts that are dispersed among flowers by wind, insects and birds,” they said. “We imposed dispersal limitation on individual flowers and quantified microbial abundance, species composition and microbial effects on nectar chemistry.”
This work has direct implications for conservation of many organisms in addition to bacteria and yeast, suggesting that preserving routes of dispersal among habitat patches may be important in the maintenance of biodiversity. In contrast to previous work showing that dispersal can homogenize communities or make them more similar, the published work demonstrates that dispersal can in some cases generate communities that are more different from each other. The authors hypothesize that this could be driven by priority effects, where early arriving species change the species that can establish within that habitat.
Why focus on nectar-inhabiting microbes? Previous work by Vannette and others shows that microbial activity in nectar can alter nectar chemistry and influence plant-pollinator interactions by altering nectar chemistry. In the Ecology Letters study, microbes were also found to change nectar chemistry, explaining ~50% of the variation in sugar composition in the field. This suggests that nectar-inhabiting bacteria and yeast can influence the nectar rewards available to pollinators in a natural setting.
More broadly, “Studying the role of microbes in the environment addresses one of the biggest mysteries in science,” Vannette says. In her current work, she and her lab are investigating how microbial communities form, change, and function in their interactions with insects and plants. They are also researching how microorganisms affect plant defense against herbivores and plant attraction to pollinators.
Vannette, a former postdoctoral fellow at Stanford, joined the UC Davis Department of Entomology and Nematology faculty as an assistant professor in 2015.
Vannette's research was funded by the Gordon and Betty Moore Foundation through the Life Sciences Research Fellowship. Stanford also funded the research through grants from the National Science Foundation, the Terman Fellowship, and the Department of Biology at Stanford University.
- Evolution of floral signals and flower morphology
- Pollinator-drive speciation
- Evolution of floral mimicry
For upcoming seminars, download this PDF
In newly published research in the journal Ecology, Vannette noted that floral nectar is produced by many plants to reward pollinators, but this sugary secretion often contains chemical compounds that are bitter tasting or toxic, and can deter pollinators. Plants including citrus (Citrus), tobacco (Nicotiana), milkweed (Asclepias), turtlehead (Chelone), Catalpa, and others produce nectar containing bioactive compounds, including deterrent or toxic compounds.
“This poses a paradox of toxic nectar: why are deterrent or harmful compounds present in a resource intended to attract pollinators?” she asked. “One hypothesis is that these compounds reduce microbial growth, which could otherwise spoil the nectar resource.”
Vannette, an assistant professor in the UC Davis Department of Entomology and Nematology, and her colleague Tadashi Fukami, associate professor at Stanford University, tested this hypothesis by growing yeasts and bacteria in sugar solutions spiked with a chemical compounds that are found in nectar.
“We examined effects on the growth of microbes isolated from nectar and non-nectar sources. Contrary to expectations, chemical compounds only weakly inhibited microbial growth in most cases. Interestingly, some microorganisms even grew better in the presence of plant compounds, like nicotine. But most surprising, we found that microbial growth in nectar reduced nectar toxicity, decreasing the concentration of chemical compounds in some nectar solutions.”
Microbial effects on nectar, in turn, increased consumption of nectar containing chemical compounds by honey bee pollinators, she said. “We found that microorganisms in nectar can both reduce the concentration of some plant compounds in nectar and increase consumption of nectar that does contain these compounds. This indicates that although ‘toxic nectar' does not strongly inhibit microbial growth in nectar, microbes modify the palatability of nectar to pollinators, which can change foraging behaviors and may reduce selection on this trait in nectar.”
The paper, exploring the effects of nectar-inhabiting microbes on chemical compounds found in nectar and nectar consumption by pollinators, “demonstrates that the compounds in nectar—such as on citrus blossoms--do not inhibit microbial growth, Vannette said. “However, yeasts and bacteria that grow in nectar can modify the effects of plant chemical compounds on pollinator foraging and nectar consumption..”
In her abstract, Vannette wrote “Secondary metabolites that are present in floral nectar have been hypothesized to enhance specificity in plant-pollinator mutualism by reducing larceny by non-pollinators, including microorganisms that colonize nectar. However, few studies have tested this hypothesis. Using synthetic nectar, we conducted laboratory and field experiments to examine the effects of five chemical compounds found in nectar on the growth and metabolism of nectar-colonizing yeasts and bacteria, and the interactive effects of these compounds and nectar microbes on the consumption of nectar by pollinators.”
“In most cases, focal compounds inhibited microbial growth, but the extent of these effects depended on compound identity, concentration, and microbial species. Moreover, most compounds did not substantially decrease sugar metabolism by microbes, and microbes reduced the concentration of some compounds in nectar. Using artificial flowers in the field, we also found that the common nectar yeast Metschnikowia reukaufii altered nectar consumption by small floral visitors, but only in nectar containing catalpol. This effect was likely mediated by a mechanism independent of catalpol metabolism. Despite strong compound-specific effects on microbial growth, our results suggest that the secondary metabolites tested here are unlikely to be an effective general defense mechanism for preserving nectar sugars for pollinators. Instead, our results indicate that microbial colonization of nectar could reduce the concentration of secondary compounds in nectar and, in some cases, reduce deterrence to pollinators.”
The research, “Nectar Microbes Can Reduce Secondary Metabolites in Nectar and Alter Effects on Nectar Consumption by Pollinators,” appears on the Ecology website, http://onlinelibrary.wiley.com/doi/10.1890/15-0858.1/full
The research was funded by the Gordon and Betty Moore Foundation, the National Science Foundation, and Stanford University.
Future work will examine how microbial modification of nectar traits influences floral attractiveness, how microbial growth may modify the specificity of plant-pollinator interactions, and if microbial effects vary among plant species.
Vannette, a former postdoctoral fellow at Stanford University, joined the UC Davis Department of Entomology and Nematology in September 2015. “I am interested in understanding and predicting how microbial communities influence interactions between plants and insects,” she said. “In the Vannette lab (in Briggs Hall), we use tools and concepts from microbial ecology, chemical ecology, and community ecology to better understand the ecology and evolution of interactions among plants, microbes and insects."
Ecology journal research paper