Study: Native Plants & Native Cultivars: Understanding Pollinator Preference for Native Plants and their Cultivated Counterparts in the Pacific Northwest
Thank you for your interest our survey! We are done collecting survey responses at this time. If you previously took the survey and have any questions, please direct them to Gail.Langellotto@oregonstate.edu and/or Jen.Hayes@oregonstate.edu.
This article was written for the regular column that I submit to the Hardy Plant Society of Oregon (HPSO) Quarterly Magazine. I am grateful to the team at HPSO for their editorial skills and feedback, that always improve what I write.
No Mow May is an initiative that was started in 2019 by Plantlife, a non-profit that works to restore meadow habitats in the United Kingdom. Their annual campaign called on garden owners and greenspace managers to cease mowing in the month of May, in order to move lawn-dominated yards towards a more natural approach. The movement quickly spread to other regions of the globe, as an easy and feel-good measure that almost any land manager could take to promote biodiversity and protect pollinators. In the United States, Bee City USA adopted the No Mow May campaign, which they also refer to as Mow Less Spring, as a way to conserve native pollinators.
There is some science to support the notion that less-intensely managed lawns benefits biodiversity. Our lab group even wrote about it in a blog post on No Mow May, including sharing a meta-analysis of 14 studies from North America and Europe showed that plant diversity and invertebrate diversity increased in lawns, as mowing intensity decreased [1]. However, several studies included in this review had mowing treatments that are not generally practical for most residential yards. Some studies compared lawns mowed once per week to lawns that were mowed once per year, for example. One of the few studies that compared mowing frequencies that approximate real world conditions was conducted in Springfield, Massachusetts [2]. In this study, Dr. Susannah Lermann and colleagues compared bee abundance and diversity from yards mowed every week, every two weeks, and every three weeks. Lawns mowed every three weeks had 2.5X more lawn flowers than other lawns. Interestingly, lawns mowed every two weeks had the highest bee abundance, but lowest bee species richness. The authors speculate that the higher grass height of the three-week mowed lawns covered lawn flowers, and made them less accessible to many bees. The higher lawn height also made the three-week mowed lawns less acceptable to nearby neighbors, leading the authors to suggest that a ‘two-week regime might reconcile homeowner ideas with pollinator habitat’.
That brings us back to No Mow May, and whether or not there is science to support the idea that not mowing for an entire month might benefit pollinators. In 2020 (soon after the start and spread of No Mow May) Del Toro and Ribbons published a paper that suggested that households that observed No Mow May had three times more bee species and five times higher bee abundance than spaces that were regularly mowed [3]. The results were highlighted in a New York Times story [4], and resulted in a change in the City of Appleton code that suspended an 8” lawn height restriction for the month of May, via a 6-3 split vote for and against the resolution [5]. Israel Del Toro, lead author of the study, was elected to Appleton’s Common Council, soon after leading the effort to adopt the resolution. By 2022, an additional 25 U.S. cities had followed suit [6], with their own declarations in support of No Mow May.
As the No Mow May movement grew, so did controversy surrounding the Del Toro and Ribbons study. Bee taxonomist Zach Portman noted serious issues with the bees identified in the study. Horticulture Professor Bert Cregg noted that the study was confounded, by comparing home lawns that were not mowed to park spaces that were mowed. With this experimental design, it is impossible for the authors to disentangle the effects of mowing (e.g. mowed or not mowed) from the effects of habitat type (e.g. home lawn versus park). In November of 2022, the authors retracted their study ‘after finding several potential inconsistencies in data handling and reporting’. After the retraction, the City of Appleton considered a resolution to eliminate No Mow May, claiming that the program lacks scientific backing. However, this resolution did not pass [7].
What is a science-informed gardener to do, amidst confusing and sometimes conflicting messaging related to pollinator conservation in a yard? First, note that science self-corrects, when the system works well. Retractions are part of that corrective process. Second, remember that bees can be found in lawn areas, particularly if lawns are less managed. The Lermann study demonstrated that lawns can host a surprising richness of bee species: 72, 60, and 62 bee species, in lawns mowed every week, two weeks, or three weeks, respectively. Note that to be part of this study, homeowners had to agree to not use herbicides or irrigation, during the length of the study. As a result of reduced management, lawns in this study often had bare patches that might be good nesting habitat for soil-nesting bees. Relaxing your mowing regime to every 1-2 weeks is supported by good science. Stowing your mower for an entire month is not. Finally, if you want to manage your yard for pollinators, planning and planting a pollinator garden is likely to net more species than stowing your mower. Indeed, many critics of the No Mow May movement, including native plant advocate Doug Tallamy, suggest that providing a temporary safe haven, regardless of its length of time, is counterproductive for pollinators and other wildlife it was meant to benefit. We currently have a paper in review, addressing this very topic. I look forward to sharing the highlights with readers, once it is published.
[1] Journal of Applied Ecology 57: 436-446
[2] Biological Conservation 221: 160-174
[3] PeerJ 8:e10021
[4] New York Times, March 28, 2022.
[5] Appleton Common Council resolution and vote, April 1, 2020.
[6] NBC 26 Local News, April 22, 2022.
[7] Post Crescent, April 10, 2023.
This note comes from our collaborator at the University of Oregon, Dr. Gwynne Mhuireach. Dr. Mhuireach previously worked with our lab and local gardeners to document soil microbial communities, and the extent to which the act of gardening transfers soil microbes to gardeners’ skin ~ thus affecting the skin microbiome!
At the conclusion of the skin microbiome study, many gardeners asked for more information on how gardening affects the gut microbiome. Dr. Mhuireach received USDA funding to conduct a pilot study, to address this question. Gardeners in Linn and Lane Counties are specifically invited to apply.
The deadline to apply to participate in this NEW study is August 15th.
We are seeking healthy adult gardeners to engage in a research study exploring microbiota of fresh fruits and vegetables from gardens and supermarkets, and their potential to influence the gut microbiome. To be eligible, you must be between the ages of 18–45, be fluent in English, live in Lane or Linn County, and have access to a garden that can provide enough fruits and vegetables for the diet intervention. Participants will receive $50 at the beginning of the study, $50 upon completion, and a $75 allowance to purchase supermarket fruits and vegetables.
Study activities: If you participate, you will be asked to undergo two week-long diet intervention periods during which you will eat the USDA-recommended amount of fruits and vegetables. In one period all of the produce should be sourced from your garden and in the other the same produce should be sourced from a supermarket. You will be also asked to pre-plan your meals for the intervention periods, complete a Lifestyle, Health, & Diet Questionnaire, maintain a Daily Fruit & Vegetable Log, collect samples of all the fruits and vegetables you eat, collect stool (fecal) samples, and collect a tapwater sample. The total duration of participation is 24 days, with an expected average time commitment of 20–30 minutes per day.
Potential risks: Participants will be exposed to microorganisms from garden and supermarket produce, however, this exposure occurs during normal daily life. There is also a risk that privacy or confidentiality could be breached, though precautions will be taken to avoid such breaches.
Benefits: There are no direct benefits to participating in this study.
To see if you are eligible, please use this Qualtrics link (https://oregon.qualtrics.com/jfe/form/SV_9Gn0UOtZEbzWEh8) to take a brief screening survey. More information is available at www.gffstudy.com.
On the last day of pride month, I read an article that brought me to tears: Can Entomology Emerge as a Role Model Field of Study for LGBTQ+ Inclusion and Visibility? by Michael C. Cavallaro. This year has been extremely difficult for the LGBTQ+ community, and to read about the successes and progress made in my field towards LGBTQ+ inclusion warmed my heart and gave me hope for my fellow queer bug lovers.
Before we dive in to the article, I want to share why this topic is important to me. I identify as a queer entomologist in two ways: 1) I am queer and I am an entomologist, and 2) I am interested in the ways that entomology expands and defies western understanding and expression of gender. The natural world, especially insects, teaches us that queerness is inherently natural and expressed in diverse ways.
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Cavallaro begins the article discussing “Shared Traits: Entomologists and LGBTQ+ Folks” by Rae Olsson, which mirrors many conversations I have had with my fellow queer entomologists. Us folks who grow up chasing, collecting, and admiring insects tend to be viewed as weird, odd, or even outcasts. Queer folks are often far too familiar with the feeling of being marginalized, othered, and at odds with society. But, there is an odd comfort in knowing that you are a weirdo studying something weird.
The article continues, noting the advances that ESA (The Entomological Society of America) has made in providing an inclusive environment for LGBTQ+ folks and elevating their voices. We have seen these advances in the form of inviting people to include their pronouns on the annual event badges, introducing symposia on Diversity, Equity and Inclusion (DEI) issues, and removing states with anti-LGBTQ+ laws from potential future meeting locations. He also points out recently identified insects that have been bestowed names of queer icons, which I wrote about during last year’s pollinator week post.
Cavallaro reports that 7.2% percent of ESA members have identified themselves as LGBTQ+, which reflects the U.S. national average. He notes that STEM still has many barriers to overcome as it is “rooted in a competitive and heteronormative culture” and “workspaces for queer-spectrum STEM professionals and students can be unsupportive and exclusionary.” Both STEM and entomology still have a long way to go in terms of acceptance, encouragement, and representation of queer folks.
As someone who attended a prestigious field entomology program and was called a “disney princess” on the first day, I can attest to the flippancy with which queer folks and femme-presenting folks are often treated in professional entomological spaces. It is, however, validating to witness the largest entomological organization in the U.S. taking the time to address, welcome, and better their ability to support their LGBTQ+ membership.
What is an ecolawn?
An ecological lawn, or ecolawn, is a reduced input alternative to a conventional mowed grass lawn. While numerous possibilities for an ecolawn exist, they all include multiple low-growing herbaceous plants that work well together and require less mowing, fertilizer and irrigation. In addition to reducing maintenance and resource utilization, they also provide important habitat for pollinators like bees and butterflies.
Help us find examples!
We are looking for examples of beautiful ecolawns throughout western Oregon. A few requirements:
We want to find, understand and share your (or your neighbor’s) ecolawn. Ecolawns are part of a more sustainable future for Oregon. If you have a good example, please email 2-3 photos and contact information to Dr. Phil Allen, Visiting Professor in Horticulture at Oregon State University: allephil@oregonstate.edu
Hi, everyone! My name is Kailey Legier and I am an undergraduate student pursuing a double-degree in Soil Science and Sustainability. I have joined the OSU Garden Ecology Lab as a field and lab research assistant! I jumped at the opportunity to join this lab because it aligned so well with what I’m passionate about: sustainable urban horticulture, insects, and learning.
I grew up in the Pacific Northwest, just about three and a half hours north of Corvallis, and from an early age I was a big fan of creepy-crawlers. Baby-Kailey could often be found toting around a plastic critter keeper full of insects that she had indiscriminately caught and dug up.
Now, as an adult, I remain a big fan of insects of all kinds and an advocate for nurturing a childlike sense of wonder for the natural world in both myself and my community. I believe that the feeling of rich, damp soil between your fingers, the tickle of a lady beetle traversing the landscape of your arm, and the sound of native pollinators buzzing through your home garden are imperative pieces to the study of garden ecology. In my spare time, I grow flowers with a specific interest in perennial cut flower beds and bulb flowers.
My research interests include subsoil insect diversity, soil health, and the family Carabidae — the ground beetles! There is something amazing about knowing the soil is full of curious little critters working full time jobs eating pests, chomping on weed seeds, and churning the soil slowly but surely.
Aside from hard science pursuits, I am invested in social equity and sustainability at Oregon State. I am a big fan of attending town halls and being politically active on sustainability and ecological issues.
I am so excited to join this lab as it serves as a confluence for quite a few of my interests and passions. I am surrounded by incredible people each day, and it is a huge honor to be able to glean knowledge from them and gain experience in this setting.
This article was originally written by Gail Langellotto for publication in the Hardy Plant Society of Oregon Quarterly Magazine, available to HPSO members.
You are what you eat. This phrase can be traced back to an 1826 essay by Anthelme Brillat-Savarin, who wrote ‘Tell me what you eat and I will tell you what you are.’ Diet and health are inextricably linked for almost all animals, including bees.
Bees foraging from flowering plants obtain carbohydrates from nectar. Pollen provides protein, fats, and vitamins. While the quantity of food is provided by the abundance of floral plantings, the quality of food is determined by the diversity of floral plantings. This is because different flowering plants offer different nutrients to bees’ diets. And, different bees have different nutritional requirements that vary among species, or that vary across life stages of a single species. For example, mason bee larvae (Osmia bicornis) larvae performed best on carbohydrate rich diets. Fluctuations in protein made little different to bee health, but carbohydrate deficiencies slowed mason bee larval growth and reduced survival[i]. Bumblebees (Bombus terrestris) foragers select foods that provide a target mix of 71% proteins, 6% carbohydrates, and 23% lipids[ii].
Diverse floral plantings also help to reduce bee disease. Flowers have been shown to be hotspots for bee disease transmission. If you think of a flower as an elementary school drinking fountain, it makes sense that a sequence of bees could be exposed to disease carried by previous floral visitors. Following a visit by parasite-infected bumblebees, some flowering plants (such as milkweed or bee balm) harbored more bee pathogens than others (e.g. thyme or snapdragons) [iii]. And here’s a fun fact you have likely never come across before: bees preferentially poop on seaside daisy compared to a variety of other flowering plants in the Malvaceae, Verbenaceae, or composites with less floral area in disk flowers[iv]. Planting diverse flower types diffuses interactions between healthy and diseased bees. Not all floral morphologies effectively hold and transfer disease. And, planting diverse plant types provides more foraging options for bees, which can limit opportunities for healthy and diseased bees to come into contact.
While some flowers may be hotspots for bee disease transmission, others provide anti-microbial compounds that help some bee to naturally fight disease. The common eastern bumblebee (Bombus impatiens), but not the brown-belted bumblebee (Bombus griseocollis) was able to fend off parasite infection after consuming sunflower (Helianthus annuus) pollen[v].
Research on the nutritional ecology of wild bees is relatively young. And, from what we’ve learned thus far, different bee species have different nutirtional needs. It’s thus impossible to provide a specific garden plant recipe that can promote optimal bee health. Nonetheless, a few key points are clear. Monocultural cropping systems are harmful to bee nutrition. Just as you or I could not achieve optimal health by limiting our diet to one food item, neither can bees. And, this nutritional harm that monocultural cropping systems presents to bees doesn’t even consider the increased pesticide applications that single-cropped systems generally require. Gardens, on the other hand, are better poised to meet the nutritional requirements of bees, by virtue of the diverse flowering plant community that is typical of most gardens.
Thus, in case you need a reason to go out and discover new flowering plants for bees and other beneficial insects in your garden, bee nutrition is yet one more reason to build biodiverse plantings into your garden design.
[i] Austin and Gilbert. 2021. Solitary bee larvae prioritize carbohydrate over protein in parentally provided pollen. Functional Ecology 35: 1069-1080. https://doi.org/10.1111/1365-2435.13746
[ii] Kraus et al. 2019. Bumblebees adjust protein and lipid collection rules to the presence of brood Current Zoology 65: 437-446. https://doi.org/10.1093/cz/zoz026
[iii] Adler et al. 2018. Disease where you dine: plant species and floral traits associated with pathogen transmission in bumble bees. Ecology 99: 2535-2545. https://doi.org/10.1002/ecy.2503
[iv] Bodden et al. 2019. Floral traits predict frequency of defecation on flowers by foraging bumble bees. Journal of Insect Science 19: 1-3. https://doi.org/10.1093/jisesa/iez091
[v] Malfi et al. 2023. Sunflower plantings reduce a common gut pathogen and increase queen production in common eastern bumblebee colonies. Proceedings of the Royal Society B 290: 20230055. https://doi.org/10.1098/rspb.2023.0055
A study of leafcutter bees and a PNW native flower, through the lens of iNaturalist.
The Clarkia Project team: Mallory Mead, Jen Hayes, Sarah Erskine, and Ali Filipovic
If you are a subscriber to our blog, you have likely seen our photos and videos of one of our favorite plant-pollinator interactions: the petals of Farewell-to-Spring (Clarkia amoena) being harvested by leafcutter bees!
After observing this eccentric harvest behavior in the research garden, we got curious about the bees behind the petal-nest craft, and how we could study this interaction further.
iNaturalist is a popular community-supported biodiversity database that the Garden Ecology Lab has been experimenting with in recent years. Jen realized that the leafcutter bees’ distinct crescent-shaped mark are visible in many iNaturalist observations of Clarkia amoena. She wondered how we could use the already sizeable iNaturalist database of Clarkia amoena observations to study the interaction over a wider geographic and chronological scale than that of the research garden. Jen and Gail agreed to mentor me in producing an undergraduate research thesis on this subject.
The study’s objective is to use iNaturalist’s data on Clarkia amoena to see if there is a difference in leafcutter bee usage of Clarkia amoena petals based on whether the flower is a native versus a cultivar type, and whether the flower is found in an urban or non-urban environment.
In this process we have found that iNaturalist is easy for anyone to contribute to, but the information it provides is limited compared to the wealth of contextual information gained when being in the actual, living presence of a specimen. So, to get a greater feel for the intricacies of this flower, I embarked on what we called “Ground-Truthing Field Trips” to check out some Clarkia amoena populations in the “real world”.
I went out during peak pollinator season, following the coordinates of recently posted iNaturalist observations. Each specimen I visited was incredibly different from the next. I found the delicate blossoms in natural areas, the borders of farmland, restoration sites, and gardens.
Data from these trips will not be published in my thesis because the contexts are not exactly comparable, and my sampling was exploratory rather than precise. Nonetheless, I gained contextual insight and inspiration watching diverse pollinator assemblages in beautiful meadows of pink.
The field trips have helped us more clearly see through the window of iNaturalist and have informed the methodology we use.
For example, I saw examples of hybridization between two species of Clarkia in a seeded restoration site, and cultivar-hybrid escapees in natural areas. It’s been important to navigate identification of cultivars and hybrids in iNaturalist.
In a restoration prairie seeded with two different Clarkia species, pollinators cross-pollinate them, giving rise to sterile hybrids (Lewis & Raven, 1958). Note the malformed stigma and anthers.
Simultaneously, our field crew recorded petal-cutting behavior on the Clarkia amoena natives and nativars at Jen’s research garden this summer. Below are the three cultivars in the garden, and if you look closely you can see “petal-cuts” which we counted and recorded weekly. We will analyze the difference in leafcutter usage between the cultivars and native type.
Clarkia amoena is an annual that reseeds itself effectively, so last year’s seeds gave rise to this season’s blooms. To our surprise, however, Clarkia amoena of all different colors started popping up in our research plots this Spring! Last season’s bees had combined pollen from the garden’s varieties bringing rise to all sorts of intermediate forms.
Clarkia amoena is prone to hybridization between members of the species or cultivars in the same proximity. These intraspecific hybrids are fertile. We seek to explore how cultivar genetics may be moving into natural populations.
Through the winter, our team is working with the iNaturalist data to quantify leafcutter bee petal usage. We expect to share our results in June 2023, so stick around to hear about our findings!
Work Cited:
Lewis, H., & Raven, P. H. (1958). Rapid Evolution in Clarkia. Society for the Study of Evolution, 12(3), 319–336.
Insect collections are a good hobby to have, and an even better tool for research. One might think you just go catch insects and pop them into a box, but a little more needs to happen in order to preserve them for a collection.
Depending on your collection method, washing, blow drying, pinning, and labelling all need to happen to keep our collection usable!
After doing these steps and putting them in a box, our wonderful Jen Hayes and taxonomists will identify them to species. There are so many morphs and intricacies that you may not even realize two look-alike bees may just be completely different species. My favorite thing about the process is seeing the fluffy bumblebees after blow-drying! 🐝
Anyways, here’s a short video showing how we go from catch to box!
This summer we completed our third and final field season surveying pollinator visitation to native plants and native cultivars! We will maintain our experimental garden for one additional season, to finish up some plant measurements and data collection missed in our initial three seasons. This post will serve as a 2022 field update in addition to summarizing some of our preliminary results from our field observations!
| Photo | Scientific Name | Common Name | Plant Type |
|---|---|---|---|
 | Achillea millefolium | Yarrow | Native |
 | Achillea millefolium ‘Calistoga’* | Yarrow | Cultivar |
 | Achillea millefolium ‘Salmon Beauty’ | Yarrow | Cultivar |
 | Achillea millefolium ‘Moonshine’** | Yarrow | Cultivar |
 | Aquilegia formosa | Western Red Columbine | Native |
 | Aquilegia x ‘XeraTones’ | Cultivar (hybrid) | |
 | Camassia leichtlinii | Great Camas | Native |
 | Camassia leichtlinii ‘Caerulea Blue Heaven’ | Great Camas | Cultivar |
 | Camassia leichtlinii ‘Sacajawea’ | Great Camas | Cultivar |
 | Symphyotrichum subspicatum | Douglas’ Aster | Native |
 | S. subspicatum ‘Sauvie Sky’ | Douglas’ Aster | Cultivar |
 | S. subspicatum ‘Sauvie Snow’ | Douglas’ Aster | Cultivar |
 | Clarkia amoena | Farewell-to-spring | Native |
 | Clarkia amoena ‘Aurora’ | Farewell-to-spring | Cultivar |
 | Clarkia amoena ‘Dwarf White’ | Farewell-to-spring | Cultivar |
 | Clarkia amoena ‘Scarlet’** | Farewell-to-spring | Cultivar |
 | Eschscholzia californica | California Poppy | Native |
 | E. californica ‘Mikado’ | California Poppy | Cultivar |
 | E. californica ‘White’ | California Poppy | Cultivar |
 | E. californica ‘Purple Gleam’** | California Poppy | Cultivar |
 | Nemophila menziesii | Baby Blue Eyes | Native (California) |
 | N. menziesii ‘Penny black’ | Baby Black Eyes | Cultivar |
 | N. menziesii ‘Snow White’ | Baby Blue Eyes | Cultivar |
 | Sidalcea asprella ssp. virgata*** | Rosy checkermallow | Native |
 | Sidalcea malviflora ‘Purpetta’*** | Cultivar | |
 | Sidalcea malviflora ‘Party Girl’*** | Cultivar |
We conducted 5-minute visual observations on our study plants over three seasons. During these observations, we recorded all insects that interacted with a plant. These interactions included foraging, resting, basking, mating, etc. We recorded insect IDs to morphological group levels, as many bees are hard to identify to species in the field! We were able to identify common bumble bees, honey bees, butterflies, and a few other insects to the species level, but many were identified to groups for ease (e.g. ‘green bees’, ‘black bees’, ‘leafcutter bees’).
| Year | # Sample Dates | # Collected Pollinators | # Observed Pollinators |
|---|---|---|---|
| 2020 | 28 | 2159 | 6238 |
| 2021 | 33 | 2471 | 6225 |
| 2022 | 29 | ~2000 | ~4700 |
Our initial graphs show a subtle preference for native types by native bees. Douglas’ Aster, California Poppy, Farewell to Spring, and Columbine (4/7) have higher visitation by native bees when looking at cumulative and mean counts. The difference is marginal for Douglas’ Aster, but trends for the other three plants are strong. The remaining three species (Yarrow, Baby Blue Eyes, Camas) are difficult to assess, based on these figures alone.
Across these seven species, we do see differences in visitation between natives (wild types) and native cultivars. Whether these differences are statistically significant, and whether there is a trend across all plant groups, remains to be seen!!!
I want to recognize my amazing Bee Team this year, as this field season would not have been possible without them! I am grateful for all of their hard work and their success in managing this project while I was away numerous times this season. They are thoughtful, inquisitive, and resourceful students, all of whom would make amazing lab or field technicians upon their graduation this spring! Nicole is not pictured below, but also deserves recognition for all her contributions to this project. Thank you all 🐝
