Flowers and bees have one of the most well-known symbiotic relationships ever formed. Flowers rely on bees for pollination, and bees rely on flowers for nectar and pollen. It is generally understood that flowers act as advertisements to attract bees. However, less is known about what exactly bees are seeing and how that can change once humans get involved. This project is focused on the changes that can arise after a plant is cultivated, and how these changes can affect pollinator preference of a flower.
While changes made by breeders might not seem all that drastic to our eyes, we have little idea if that is the case for bees. Often breeders will change flowers for aesthetic purposes. This can have unknown consequences. These changes might not seem like such a big issue since the flowers are still colorful. However, bee vision is very different from humans, with bees having the ability to see into the UV spectrum. This means that while we might think we are only changing the bloom size or the color, we could also be unintentionally changing UV messaging visible only to the bees.
The purpose of this study is to use UV photography to explore these invisible differences between the native and cultivar. We also want to determine if the differences have a tangible impact on pollinator preference. This study is ongoing, but the images so far have shown a few native/cultivar sets that have a marked difference in UV markers between native and cultivars. While the study has only just started, our excitement and curiosity have not abated. This is an entirely new foray into pollinator relationships and mechanisms and could open up the world of bees and flowers in a brand new way.
I’m pleased to present the work of my very first field season as a master’s student here at OSU. My project centers around presumptive sterile cultivars of Buddleja, or butterfly bush. Over the next few years, I will be studying how breeding for sterility affects pollinator attraction, pollinator nutrition, and if this breeding is truly effective in slowing the invasiveness of this particular plant. The hope is that this research will be able to serve as a framework for assessing putative sterile varieties of other potentially economically lucrative, but invasive, ornamentals.
Buddleja davidii was designated as a B-list noxious weed in 2004, and was placed in quarantine in conjunction with this designation. Since then, the ODA (Oregon Department of Agriculture) has begun to allow sale of B. davidii cultivars that display a 98% reduction in fertility in comparison to fully fertile ‘old school’ cultivars such as ‘Black Knight’ or ‘Nanho Blue’. At the moment, 14 cultivars of Buddleja davidii are legal to sell, propagate, transport or import in Oregon though no science has been conducted to assess how a reduction in fertility actually translates to reduced weediness.
The other questions I am researching are how pollinators behave around these new, ‘sterile’ cultivars in comparison to how they interact with fertile ones, and what kind of nutrition pollinators can obtain from sterile varieties. These are ever more important questions as we continue to put pollinator health at the forefront of plant selection decisions. To that end the team has been conducting timed pollinator counts through the summer in the test plot.
The test plot is located at Lewis-Brown Horticulture Farm, in the beautiful countryside surrounding Corvallis, Oregon. There, we have randomly allocated six to nine replicant plantings of six fertile cultivars and 28 putative sterile cultivars. Working in this gorgeously fragranced field (seriously-think notes of honey, spice, and fruit) has been a true delight all summer. Cultivars of Buddleja run the gambit in terms of color, plant habit, and floriferousness. There is everything from Buddleja ‘Purple Haze’, a prostrate variety with blue-violet flowers, to my personal favorite, Buddleja x weyeriana ‘Honeycomb’, an absolutely uprightly enormous variety with unique yellow blooms.
Once a week, I go to the field and determine which of the 204 plants are at maximum flower. These plants are slated for our weekly pollinator counts. To conduct a pollinator count, we simply set a timer for 5 minutes and watch the plant for visitors. These visitors are identified to morpho-type in the field (i.e. Honeybee, Bumblebee, Syrphid fly, Butterfly…). Here are the full counts for this season:
You may notice that there are less than 34 cultivars on this graphic! That is because we are in possession of several cultivars that have yet to be released to the general public, so unfortunately, I cannot share them here with you today. It does seem clear, for this season at least, that honeybees are the most prevalent visitor of butterfly bush. Though we can’t draw conclusions from this season’s data alone, we hope that with a few more seasons of data we will be able to identify patterns of attraction and biodiversity. Until then I will be back in classes and working on other aspects of my research-looking forward, of course, to next field season.
Our colleague, Brooke Edmunds, was kind enough to shoot and edit this short video on two of our current lab projects: Jen Hayes’ study of native plants and nativars and Tyler Spofford’s study of the economic costs and benefits of growing vegetables in bucket gardens.
As we near the end of our 2020 field season, stay tuned for research updates.
COVID-19 has impacted our research in many different ways, including making it more difficult to find time to provide research updates on a regular basis. Despite the long silence, we have many projects up and running this summer! In fact, we’re launching four new projects, finishing up three long-term projects, and writing up another two projects.
In this blog post, I give a brief overview of the four new Garden Ecology Lab projects that launched this summer.
Microbiome of Garden Soils and Gardeners: Dr. Gwynne Mhuireach’s project has been spotlighted in a recent blog post and webinar. She has selected the 40 gardeners that will be included in her study: 20 high desert and 20 Willamette Valley gardeners, half of whom are organic and half of whom are conventional gardeners. Soon, these gardeners will be sending in their soil and skin swab samples. And then, the long process of analysis will begin.
She’s studying the microbe community in garden soils, and how those might differ according to garden region (Willamette Valley or high desert) and gardening practices (organic versus conventional soil managmeent). She’s also studying whether garden soil microbes transfer to gardeners’ skin during the act of gardening, and if so, how long those microbes persist on the skin.
Jen’s field site is located at the Oak Creek Center for Urban Horticulture at OSU, which makes it so much easier for undergraduate student researchers to participate in this project. She samples pollinators on Tuesdays and Fridays. She takes 5-minute observations of pollinator visits on Mondays and Thursdays. In between, lots of time is spent weeding and watering plots, counting flowers, and measuring floral traits.
Cost / Benefit Analysis of Growing Edible Plants in Containers: Tyler Spofford is a new lab member, who is completing his undergraduate degree in the BioResource Research program at OSU. He is working to develop a ‘budget’ for growing food in low-cost containers. I’ve summarized this ‘budget’ data for growing food in standard vegetable gardens, but no data yet exists (that I can find) for containerized vegetable gardens. Tyler is growing 40 tomato plants across two sizes of containers (3 gallons and 5 gallons), as single plants and in combination with basil. He’s keeping track of all of the costs (both money and time spent to grow food). When he harvests food, he’ll weigh his harvest, and track the economic benefit of his efforts, and how container size and planting configuration (one or two crops per container) influences harvest. I’ve set up a Flickr album for his study, to host project photos.
Tyler’s project grew out of my concern that, even though 18,000+ people enrolled in a free, online vegetable gardening course (over 40,000, at last count) ~ that the people who might be most at risk for food insecurity may not be benefitting from Extension Master Gardener resources and information. Tyler’s project is one component of a larger effort to develop more support for renters who might want to grow their own food.
Below is an excerpt from a concept paper I’m writing on the topic:
We know that the COVID-19 pandemic is exerting stress on multiple pressure points related to the economic and food security of U.S. households: more people are in need of food aid and more people are concerned about food access. The U.S. has a long history of gardening in times of national emergency (e.g. Victory Garden of WW I and WWI II, ‘recession gardens’ of 2008). The benefits of gardening as a tool of economic security and resilience are well-established. However, research suggests that these benefits are largely restricted to homeowners. Currently, most state and local laws afford no legal right to renters who want to grow their own food. Community gardens might offer renters opportunities to grow their own food, except that these gardens are often associated with gentrification. To promote public health in the face of economic and health risks of COVID-19 and future pandemics, it is critical to support the food gardening efforts of the most vulnerable. Those in rental housing have been found to be most vulnerable to food insecurity, as well as the food and economic insecurity associated with natural disasters.
Pollinators on Buddleja Cultivars: Cara Still is studying how breeding butterfly bush (Buddleja davidii cultivars) for sterilty impacts the pollinator community that visits Buddleja blossoms. Buddleja davidii and some fertile varieties of this plant are considered noxious weeds in Oregon, and many other places. Normally, noxious weed status would make it illegal to sell or trade butterfly bush in Oregon. However, the Oregon Department of Agriculture allows exceptions for non-sterile cultivars and interspecific hybrids.
Cara is studying whether or not the plants that are allowed for sale, under the exceptions, still pose a risk of invasion. Our group is working with Cara to document the abundance and diversity of pollinators that visit eight fertile Buddleja cultivars with 16 cultivars that have been bred for sterility.
When I was initially approached to participate in this project, I thought that it should be obvious that sterile cultivars would not attract pollinators. Afterall, sterile cultivars don’t produce pollen, or produce very little pollen. Without pollen, I doubted that bees would visit the plants. But, it is possible that sterile plants would still produce nectar. And, many pollinators ~ such as butterflies and moths ~ visit plants to consume nectar, rather than pollen.
The more I looked into the literature, I realized that no one has yet studied how breeding for sterility might affect a plant’s attractiveness to pollinators. Would sterile forms of butterfly bush no longer attract butterflies? Would sterile varieties attract syrphid flies that visit blossoms for nectar, and not pollen? We’ll let you know what we find, in about a two years. In the meantime, you may want to visit the Flickr album of photos I set up for Cara’s study.
The members of the Garden Ecology lab spend much of their time on research into subjects that affect, what else, the ecology of home gardens. Pollinators and their relations with native and non-native plants, bee variety and abundance in gardens, and soil nutrient levels, are among the topics they are delving into.
One of the challenges for the
lab members – and for all scientists – is how to get the results of their
research into the hands of people who can use it. Scientific papers are the
traditional way, but not many people actually read those, and it can take a
long time for research to trickle out from papers to the general public. If you
read this blog, you’ve discovered one of the ways current research is
disseminated quickly, and you’re learning new ideas that you may be able to
implement in your own research or gardening.
Another way research gets to
the public is through teaching. Lab members present new data in lectures,
interviews, presentations, workshops and classes, including OSU Extension’s Online Master Gardener training, which I teach. Each year the course reaches around
40 Oregon MG trainees, plus another 60 or so horticulturally-minded people who
take the course simply to improve their garden knowledge. In addition, our single-subject
are accessed by several thousand people per year. So any new research I can
include in these courses can potentially reach hundreds or thousands (depending
on the subject) of gardeners per year, who in turn may influence other
With this in mind, I have cited Mykl Nelson’s research on excessive nutrient levels in managed vegetable garden soils to caution students about the perils of over-fertilizing. In 2020, my new module on Gardening with Pacific Northwest Native Plants will be influenced by Aaron’s data on the native flowers most favored by native pollinators. His research, plus other research taking place elsewhere, is showing that just planting a garden of pollinator-attracting plants may not be the best tactic to help native pollinators. A garden full of bees is often, really, a garden full of honey bees. What about all the native bees that are less visible, but at least as important? Aaron Anderson’s research into which plant species attract which bee species is beginning to show that the plants most attractive to honey bees are generally not the same as those most attractive to native bees.
The takeaway? Gardeners who want to support
pollinators can take the extra step of searching out and growing native plants
that are especially attractive to native bees, in addition to the many flowers
that honey bees frequent. This is what I will be teaching my Master Gardener
trainees in Oregon, and the rest of my students all over the country; many of
them will in turn teach other people. Bit by bit the new information gets out
there, and more native bees may find the flowers they need to thrive.