- Author: Kathy Keatley Garvey
“I am interested in understanding and predicting how microbial communities influence interactions between plants and insects,” she says. The Vannette lab “uses 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."
Now the UC Davis assistant professor has two more opportunities that will enable her to pursue her research: she recently received two National Science Federation (NSF) grants.
One is a five-year Faculty Early Career Development (CAREER) Program award, titled “Nectar Chemistry and Ecological and Evolutionary Tradeoffs in Plant Adaptation to Microbes and Pollinators.” NSF grants CAREER awards to early career faculty “who have the potential to serve as academic role models in research and education and to lead advances in the mission of their department or organization,” a NSF spokesman said.
The other is a three-year collaborative grant, “The Brood Cell Microbiome of Solitary Bees: Origin, Diversity, Function, and Vulnerability.”
Vannette serves as a co-principal investigator with professor Bryan Danforth, Cornell University; research entomologist Shawn Steffan of the USDA's Agricultural and Research Service, University of Wisconsin; and assistant professor Quinn McFrederick, UC Riverside.
“Plants interact with a variety of organisms. The flowers and the nectar plants produce are adapted to attract beneficial organisms like bees or hummingbirds. However, microbes like bacteria and fungi also inhabit flowers and can reduce plant reproduction. Plant traits can reduce microbial growth in nectar, but this may also reduce pollinator visitation. This project will investigate if plants that are pollinated by different organisms (e.g. birds vs bees vs flies) differ in their ability to reduce microbial growth and if nectar chemistry is associated with microbial growth. This project will examine if nectar traits can be used to breed plants to be more resistant to harmful microbes without reducing attraction to pollinators. Resistance to microbes is beneficial in agricultural contexts where floral pathogens can limit food production but crops still rely on pollination.
“This research will link variation in plant phenotype to microbial abundance and species composition, and microbial effects on plant-animal interactions,” she noted. “This project will use a tractable system: the microorganisms growing in floral nectar, which can influence floral visitors and plant reproduction. The underlying hypothesis tested is that plant traits can facilitate or reduce microbial growth, and the community context (e.g., presence of pollinators) influence ecological and evolutionary outcomes.”
Vannette will perform the research activities using 1) a community of co-flowering plant species and 2) genotypes within California fuchsia (Epilobium canum). “Experiments will characterize variation in microbial growth, nectar chemistry, and microbial effects on plant reproduction and floral visitor behavior and the interactions of these factors,” she related in her abstract. “ Experiments and analysis will reveal how variation in nectar chemistry is associated with microbial growth and species composition in nectar, and subsequent effects on plant-pollinator interactions including plant reproduction. Experiments across Epilobium genotypes will elucidate how microbes affect microevolution of floral traits in a community context.”
The project “will engage students from a large undergraduate class to participate in practitioner-motivated research projects,” she wrote. “Students from the Animal Biology major, including in the class ABI 50A will participate in outreach on pollinator-friendly plantings for horticultural and landscaping. The project will support students recruited from diverse and underrepresented backgrounds to participate in independent projects related to project objectives, including hosting students through the Evolution and Ecology Graduate Admissions Pathway (EEGAP), a UC-HCBU program." The program connects faculty and undergraduate scholars at both UC (University of California) and HBCU (Historically Black Colleges and Universities) campuses
Collaborative Grant
The collaborative grant will enable the researchers to do cutting-edge research as they investigate the diverse community of bacteria and yeasts in the pollen and nectar diet of bees.
“Bees are the single most important pollinators of flowering plants worldwide,” the co-investigators wrote in their abstract. “Over 85% of the 325,000 flowering plant species on earth depend on animals for pollination, and the vast majority of pollination is carried out by bees. Annually, bees are estimated to contribute $15 billion to US crop production and $170 billion to global crop production. High-value bee-pollinated crops include apple and other early spring tree fruits, strawberries, blueberries, cherries, cranberries, squash and pumpkins, tomatoes, almonds, and many others. The economic viability of US agricultural production is dependent on stable and healthy wild and domesticated bee populations.”
“However, bee populations are threatened by a variety of factors, including habitat loss, pathogen spillover, invasive plants and animals, and pesticide use, which can disrupt the normal microbial symbionts essential for bee larval development (the ‘brood cell' microbiome),” they pointed out in their abstract. “This research project focuses on understanding what role microbes play in the larval nutrition in a wide variety of bee species. Previous research has documented a diverse community of bacteria and yeasts in the pollen and nectar diet of bees. As larvae consume these pollen/nectar provisions they are ingesting microbes, and our preliminary results indicate that these microbes form an essential component of the larval diet. This project has the potential to significantly modify how we view the 120 million-year-old partnership between bees and flowering plants, and will provide essential information for developing long-term bee conservation efforts. Project outreach efforts include educational activities on solitary bees for K-12 students and interactive demonstrations of bee-microbe-flower interactions for broad audiences.
The co-principal investigators said that the project will use cutting-edge methods to (1) document the microbial diversity in flowers and pollen provisions, (2) determine the nutritional role of microbes in larval development and health, and (3) understand how alterations in microbial community impact larval development.
To document microbial diversity in both host-plant flowers and pollen provisions, the research team will use amplicon sequencing and microbial metagenomics. These methods will document the microbial species present in pollen provisions as well as the metabolic activities these microbes perform during pollen maturation. Screening the pollen and nectar of host-plant species will provide key insights into the source of the brood cell microbiome. To determine the nutritional role of the microbial community the research team will use two methods from trophic ecology: compound specific isotope analysis and neutral lipid fatty acid analysis. These analyses will permit the research team to track the origin (floral or microbial) of amino acids and fatty acids in the larval diet of 15 focal bee species.
Finally, through manipulative laboratory experiments, the research team will determine how modifications of the microbial communities impact larval development. They hope by combining the results of these studies, the researchers will provide a comprehensive understanding of how bees and flowering plants interact via their shared microbial partners.
The collaborative project is funded jointly by the Systematics and Biodiversity Sciences Cluster (Division of Environmental Biology) and the Symbiosis, Defense and Self-recognition Program (Division of Integrative Organismal Systems).
Vannette, a Hellman Fellow, joined the UC Davis Department of Entomology and Nematology in 2015 after serving as a postdoctoral fellow at Stanford University's biology department. As a Gordon and Betty Moore Foundation Postdoctoral Fellow from 2011 to 2015, she examined the role of nectar chemistry in community assembly of yeasts and plant-pollinator interactions.
A native of Hudsonville, Mich., Vannette received her doctorate in ecology and evolutionary biology from the University of Michigan, in 2011. Her dissertation was entitled “Whose Phenotype Is It Anyway? The Complex Role of Species Interactions and Resource Availability in Determining the Expression of Plant Defense Phenotype and Community Consequences.”
- Author: Christine Casey
We've all seen them....garden catalogs or magazine articles with cute little bee houses hanging like birdfeeders, or entire fences made of nesting tubes for solitary bees. We even had them at the Haven -- for a while -- in the form of bee condos. The only problem? They often don't work, and may even do more harm than good.
This is not limited to bee houses; previous investigation by Mihail Garbuzov and Francis Ratnieks of the University of Sussex found similar misinformation surrounding bee plant lists. They reviewed lists published for various regions worldwide, and found large variation in recommended plants, even within the same region. The science behind the lists, such as university research or repeated monitoring by trained observers, was also often unclear.
So what's a conscientious bee gardener to do?
Bee houses
I've written extensively about solitary bee houses on this blog. In the wild, bees nest in abandoned beetle galleries in trees. This environment is dark, stationary, and made of wood, and can inform our choice of solitary bee housing. Consider the following:
1. Bees will use a nesting tube diameter that corresponds to their body size. A good range of sizes for common bees is 3/16 to 5/16 inch. Tubes should be 4 to 6 inches deep; anything shorter will produce predominantly male bees.
2. Bees will not use houses or nesting blocks that move or are open in the back
3. A shaded entrance is important; even a piece of burlap draped over the top of the nest can work
4. Bee houses constructed of wood seem to be preferred
5. Position house with entrance out of the prevailing wind
6. Pathogens can build up in bee houses as they are used; they cannot be sterilized with bleach or other disinfectants. 'Cleaning' the used nesting tube with a drill bit or brush is likely to push pathogens into the wood. Houses (in the case of wood blocks) or individual tubes should be replaced after they are used.
7. Consider all dimensions. Bees may nest in hollow stems that are not horizontal.
A fact sheet about building and using solitary bee houses is here.
Bee garden plant selection
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- Author: Christine Casey
I've had several questions recently about the Bambeco solitary bee house sold at Costco (they sell the Swiss Alps model), so I decided to head to my local store to check it out. While the price is amazing, the house has a few features that are not so ideal. For details on what makes a good solitary bee house, see here and here.
The depth. At 4.5 inches deep, it is sufficiently deep to allow the production of female and male bees.
What's not so good:
The nesting tube diameter. While the variety of diameters is good, solitary bees need tubes from 3/16 to 5/16 in diameter. While other arthropods, such as spiders, may use the larger tubes, they will not be used by bees.
Limited protected overhang. The nesting tubes should be placed so that the entrance has a bit of protection. That's why we make our houses at least an inch longer than the tubes.
The nesting tubes are glued in place. Once a tube is used it should be replaced to help prevent the build up of pathogens.
March 13, 2019: winter update
The bee house is not holding up well to the winter weather. Here's a photo showing some superficial mold as well as separation of the sides from the base. Note that I added extra protection by attached redwood fence boards to increase the cover of the roof.
March 27, 2019: comments on the 2019 model
Update July 1, 2019
The Bambeco bee house shown above is not holding up well to the weather. After three months outside (there was one week of rain during this period), the paint on the roof is peeling.
Update October 7, 2019
I have discarded the 2019 bee house. The paint continued to peel and the wood on the roof started to split. I removed the wooden blocks in the front of the house and will use these next year. For folks who have been asking what a correctly designed bee house looks like, here is an example of the one we sell at the Haven.
What makes it correct:
1. It's made out of redwood; studies have shown that bees prefer to nest in wood.
2. The depth and diameter of the nesting tubes are correct. The holes are drilled 5 inches deep, and the openings range from 3/16 to 5/16 inch in diameter.
3. Paper straws have been inserted into the 1/4 inch diameter holes (this is the only size straw available). This means that the tube can be cleaned out after use. I suggest plugging the others with wood filler after use so that they are not re-used.
4. The front of the block has a pattern to it. This may help the bees recognize their individual nest entrance. There is also evidence that a blue front is more attractive to one of the mason bee species.
5. The block has a piece of burlap shading the entrance. Bees are more likely to use the blocks if the entrance is shaded.
- Author: Christine Casey
It wouldn't be spring without strawberries....or the bees that pollinate them!
California's strawberry crop was worth $1.8 billion in 2015; our state produces 88% of the US crop. Tasty and nutritious, they are high in vitamin C, potassium, iron, fiber, and antioxidants.
High-quality fruit takes teamwork: honey bees tend to pollinate the top of the flower, while wild bees pollinate the base. Bee pollinators of almonds include mason bees (Osmia spp.), honey bees (Apis mellifera), mining bees (Andrena spp.) and bumble bees (Bombus spp.).
Strawberries are easy to grow at home.....want to improve pollination and yield in your home garden? In one study, planting wildflower strips next to strawberry field increased bee flower visits by 25%. An easy way to achieve this is to interplant strawberries with herbs and let the herbs flower.
- Author: Christine Casey
It wouldn't be spring without strawberries....or the bees that pollinate them!
California's strawberry crop was worth $1.8 billion in 2015; our state produces 88% of the US crop. Tasty and nutritious, they are high in vitamin C, potassium, iron, fiber, and antioxidants.
High-quality fruit takes teamwork: honey bees tend to pollinate the top of the flower, while wild bees pollinate the base. Bee pollinators of almonds include mason bees (Osmia spp.), honey bees (Apis mellifera), mining bees (Andrena spp.) and bumble bees (Bombus spp.).
Strawberries are easy to grow at home.....want to improve pollination and yield in your home garden? In one study, planting wildflower strips next to strawberry field increased bee flower visits by 25%. An easy way to achieve this is to interplant strawberries with herbs and let the herbs flower.