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.
My name is Mallory Mead, and I am new to the Garden Ecology Lab! I am an undergrad studying Horticulture and minoring in Entomology, and I started a few weeks ago as an assistant to Jen Hayes on her study of pollinator attraction to native plants and nativars.
I enrolled in Oregon State’s URSA Engage program, which gives undergrads a taste of research experience in the Winter and Spring of their first year, and joined a project studying how mason bees might be impacted by climate change with Dr. Jim Rivers of the department of Forest Ecosystems and Society. The study seeks to examine the effects of warming temperatures on mason bee behavior and the development of brood.
The Western US’s native species of mason bee, the Blue Orchard Bee (BOB) is known to be an excellent orchard pollinator. On many orchard crops they are more efficient at pollination than honey bees on a per individual basis, and so the commercial management of BOBs is being explored as honey bee colonies suffer management challenges and colony losses in recent years.
Mason bees have a short lifespan of 4 to 6 weeks. Emerging in the early spring, males die shortly after mating, while females build nests in holes in wood or reeds. They forage for pollen and nectar to form provision masses in which they lay their eggs. They also collect mud to form partitions between each provision mass and to cap the nest once it is full. Their offspring will feed on the provisions and metamorphose into cocooned adults to overwinter in their cells and emerge the following spring.
To ensure the bees had ample nutrient resources, the project was conducted next to the organic cherry orchard at OSU’s Lewis Brown Farm. Before the cherries bloomed, 6 nest structures were designed and constructed by Jim, Ron Spendal (a mason bee house conisuerrier) and Aaron Moore of Revolution Robotics.
Each structure has 3 shelves with 16 nest holes each, lined with paper straws so that the nests can be easily removed and examined. The structures are solar powered, and each shelf is heated to a different increment above the ambient temperature i.e. + 0°C , + 2°C, + 4°C, + 6°C, + 8°C, + 10 °C, and + 12°C. These differentials represent many potential warming outcomes of climate change.
We predicted that female mason bees will select the warmer nests first, and that females will leave nests earlier in the morning to begin foraging because they will reach the critical internal temperature necessary for flight sooner.
If heated bees have a greater window of foraging time, then we predict they’ll be able to construct nests at a faster rate in the warmer nests.
With greater nest construction will come a greater production of offspring from the bees in the warmed nests.
In terms of offspring quality, we predict that offspring of heated nests will emerge as weak individuals and mortality will be the highest for the heated brood.
…and we are pretty confident about this last prediction.
Insects are poikilothermic meaning their internal temperatures are determined by the environment. Past studies by researchers Bosch and Kemp have reported that mason bees who are overwintered at warm temperatures will “use up their metabolic reserves and are likely to die during the winter”. And a more recent study by researchers at the University of Arizona found that mason bees subjected to heating resulted in reduced body mass, fat content and high mortality of the mason bee offspring.
Our mason bees started hatching from cocoons in mid-April and began to colonize the nest structures. I captured video footage of the bees as they emerged in the morning to forage. If bees from heated nest sites emerge earlier, this will support our hypotheses that they reach their critical-for-flight temperature earlier, and get a leg-up on foraging compared to their neighbors.
I also conducted “nest checks” to track the rate of nest construction along with two other research assistants.
In the fall, the nest tubes will be extracted to examine the reproductive output, and in the following spring, offspring will be assessed for rates of mortality, offspring mass, and fat content.
Some of the challenges along the way have included dealing with insect pests. Spiders were easygoing inhabitants of the nest straws, for they only nested in empty straws, so we’d swap them out for a clean one. The earwigs were much more pervasive, and went for the already inhabited nests. As generalist foragers, the earwigs took advantage of provision balls of nectar and pollen that had not yet been sealed off by mud. Once I read that earwigs will indeed eat the mason bee eggs that are laid into the provision masses, I knew it was crucial to remove the earwigs from all nests, but these feisty creatures proved determined to stay. We ordered some tanglefoot, a sticky substance to trap the earwigs on their way up the structure post, and meanwhile I coaxed earwigs out with tiny pieces of grass. Jabbing them repeatedly would eventually provoke them to charge at the blade of grass and fall out from the straw.
Yellowjackets were another opportunistic nester. They’d sneak into the cocoon boxes to build nests, and always gave me a start when opening the tiny boxes. I removed their nests with an extended grabber tool and would destroy them in any way I could. I feel immensely lucky not to have been stung through this process.
The most terrifying surprise during the project was a fat snake that was living in the solar panel battery box. It popped out at me hissing while I conducted a routine check. Alas, I was too spooked to take on this unexpected visitor and let it leave on its own time.
Preliminary Findings & Observations
By mid-May, a pretty clear pattern was emerging. At each structure, the control shelf’s nests (+ 0 °C) were full and capped with mud, while the hottest shelves were almost completely empty. We will analyze nest check data to confirm that these patterns are not just arising by chance, but a study that was released this past April showed another species of mason bee in Poland following the same pattern of nest site preference and selection for cooler nest sites.
The mason bees’ unexpected behavior of avoiding the heated chambers may lead to trouble during the second part of the experiment because this means our sample size for heated offspring has become so tiny, but here it is important to note that this is mason bee project is a pilot study and so the data collected this year will simply influence more specific future research.
these preliminary findings make me think that mason bees have an ingrained sense to avoid warm nests, which might show mason bees’ adaptability in the face of climate change, that is, if they can manage to continue finding cool nests. People managing mason bees find that nests facing the morning sun are the most attractive to the bees, but I wonder how long it will be before temperatures rise and mason bees start avoiding these sunny nests.
By the end of May, I’d only see a few the mason bees per visit, so the season was clearly coming to an end. I wrapped up data collection and am now spending the summer extracting data from the video footage, and checking up on the bees to ensure they are safe and sound until Fall inspections.
I am wishing the best to both the wild bees in our region and those in our study, as the temperatures skyrocket this week but with this summer’s heat wave, I don’t think we need to simulate climate change; it is right here before us. Even though it is practically inevitable that temperatures will rise to dangerous heights in my generation’s lifetime, there is so much life to be saved, and there is no time to waste.
As part of Master Gardener Week at the end of October, I had the opportunity to view “Five Seasons: The Gardens of Piet Oudolf” and participate in a discussion afterwards. This recently-released film has brought renewed attention to the gardens and landscapes created by this internationally-renowned designer. His popular public garden designs, and several books, have had a profound impact on the design of public spaces, as well as private gardens.
Oudolf’s gardens have been described as spontaneous, immersive and naturalistic, and rely heavily on grasses and structural perennials to maintain visual interest well into the winter. They evoke flower-filled meadows and prairies, and seem at first glance like places that could, indeed, have occurred spontaneously. Oudolf himself acknowledges, though, that they require a certain amount of “interference”, and his design process is comprehensive and very specific. He has a palette of plants that he has tested over time for durability and effect.
During the bloom season, one imagines these gardens will be buzzing with pollinators, and be places of lively, hungry activity. When it comes to pollinators, it seems, almost any garden is better than no garden at all, and a garden doesn’t need to be designed especially for pollinators in order to offer benefits to them. As research in this lab has shown, though, a garden designed specifically to be pollinator friendly has an outsized impact.
So I wondered, how pollinator-friendly are Oudolf’s naturalistic gardens, really? On the positive side: • Lots of flowers. From early season to late, things are blooming. Plants are left standing well into winter, providing seed and shelter. • Little or no use of pesticides. • Native plants are often included, though there is no particular emphasis on them.
On the negative side: • Maintenance involves cutting everything to the ground in late winter. This destroys the winter homes of cavity-nesting bees that use the stems. At the Lurie garden in Chicago, this problem was recognized and steps were taken to leave some stems standing. • Lack of layering. The iconic Oudolf garden is composed almost entirely of herbaceous perennials, with trees and large shrubs lacking. This limits the provision of food and habitat for a variety of creatures.
I believe pollinators could be better supported by Oudolf-style gardens with three simple changes. • Keep mowed areas to a minimum. Group plants with good winter nesting stems, and leave them standing until they are covered by new growth. • Include and group small groups of larger plants such as suitable small trees and shrubs. • Prioritize native plants where possible.
If you would like to know more about Piet Oudolf’s gardens, plant choices, and design process, here are some reference materials. And if you get the chance, watch the film “Five Seasons: The Gardens of Piet Oudolf”.
Dream Plants for the Natural Garden by Henk Gerritsen and Piet Oudolf, Timber Press 2000 Essentially a catalog (although not all plants are pictured) of plants that Oudolf has culled to be “reliable plants that, over the years, can be maintained in an average garden without too much in the way of artificial props and bolstering”. Many of them “look good dead”, too. These are the plants he uses in his designs. They are divided into categories of Tough Perennials (the longest section by far), Playful Biennials and Annuals, Troublesome Invasive Plants, and Troublesome Capricious Plants – hardly the usual categories! If you are an experienced gardener and want an invaluable reference for plants that will enhance your natural garden without requiring loads of work, this book is for you.
Planting Design: Gardens in Time and Space by Piet Oudolf and Noel Kingsbury, Timber Press 2005 On the other hand, if you are not an experienced gardener, this book might be a better place to start. It is a thrifty introduction to the concepts of how gardens fit into nature, and vice versa, and how plants can be used through space – and time! – to create the desired outcomes. There are many lists of plants for specific purposes, such as Small Trees to combine with perennials, and Biennials for self-sowing, and a short but useful section on how to prepare for, implement, and maintain a planting of this sort.
Planting: A New Perspective by Piet Oudolf and Noel Kingsbury, Timber Press 2013 This book builds on the previous two, offering a detailed look at the techniques and philosophy Oudolf uses to design his gardens, as well as specific ways in which he uses plants in them. A season-by-season guide dissects various effects and combinations, and a chart towards the end concisely organizes many of the plants used. One of the most interesting concepts is that of matrix planting.
For more detail on the creation of specific gardens by Piet Oudolf, there are also books on Hummelo, the High Line, and Durslade Farm.
The Self-Sustaining Garden by Peter Thompson, Timber Press 2007 In this book matrix planting is presented in great detail. This is an effective and efficient way of designing intermingled plantings without having to specify the location of each and every plant. The matrix (often grasses) may be made up of several plant species, and serves as a stage for other, showier compatible plants embedded in it.
Dramatic Effects with Architectural Plants by Noel Kingsbury, Overlook Press, 1997 Oudolf’s chief writing partner has produced many noteworthy books himself. As the title describes, this book focuses on plants with strong and dramatic architecture. Having some of these in the mix is a key technique that makes Oudolf’s designs work.
Naturalistic Planting Design by Nigel Dunnett, filbert press 2019 With a foreword by, who else, Piet Oudolf, this is one of the most recent entries in the category of books focusing on natural or naturalistic design. It’s a dense book with at least as much text as photography, covering garden lore from historic, through contemporary, and looking to the future. Basic design principles, as they pertain to a naturalistic design, are also presented, along with a series of case studies illustrated by seasonal photos. Gardening with Native Plants of the Pacific Northwest by Arthur Kruckeberg and Linda Chalker-Scott, University of Washington Press, 2019. And finally, if you want to use PNW native plants to achieve Oudolf-like effects in your garden, this recent book is an accessible, thorough, well-illustrated guide to those plants. You will find it easy to browse through for plants that have the look you want. Symbols by each photo give a hint as to each plant’s cultural requirements.
The primary problem facing astroculture
(irrigation) and why (microgravity)
First space-grown vegetable eaten in space (lettuce)
Expansion of production area in astrocultural
trials (1000x increase)
Astroculture: growing food in space! ‘Sure, cool concept,’
you might be thinking, ‘but what does this have to do with garden ecology?’
Well, the tight confines onboard spacecraft are more constraining than most any
compact, dense city on Earth could claim. Perhaps only those in capsule-style
housing can begin to appreciate the cramped living quarters of astronauts.
The effort to grow food in space is about more than creating
a system which can reduce the need for supply shuttles from Earth. Astroculture
is the proving ground for compact, synthetic production environments. Any experiments
are as isolated as possible. This has resulted in NASA (or the National
Aeronautics Space Administration) and other space agencies playing a central
role in the development of new technologies to support the growth of plants in
From 1970 to the present there have been:
21 plant growth chamber design systems
50 different cultivation experiments
across ~40 species
The first food crop grown in space were onions in July, 1975,
by cosmonauts Klimuk and Sevastianov during the Salyut space program of the Soviet Union. They aimed a few bulbs
from the crew’s on-board lighting system at the seeded trays, but nothing more.
Some plants did germinate, and for the first plants humans have put in space,
that’s a significant enough accomplishment on its own. One of the limitations
to this and all the other experiments at this time were the short flight
durations. Only two years previous, the record time in space was set at just
eight weeks—by the United States.
NASA pioneered research into intra-canopy lighting with a
technique they called ‘lightsicles’—poles of lights which lit ever-higher as
the plants grew taller. This idea itself isn’t new. Experiments ‘on the ground’
had shown that shading out lower leaves will lead to senescence or the decay
and loss of those leaves.
See, the problem wasn’t in supplying the right spectrum of
light—controlled conditions in space quickly produced plants with lush growth
in their upper canopy. The problem they quickly realized was a shading out and
subsequent decay and loss of leaves below the plant canopy. Lights like
high-pressure sodium or metal halide were simply too hot to be placed within
the plant canopy itself. This heat also meant there was significant distance
between light source and plant. This empty space between light and plant was
the most the aeronautic agencies were willing to sacrifice to carry out these
agricultural experiments. They definitely were not going to now account for
empty space between lights on multiple sides of a plant’s growing area!
The scientists at NASA were ready and waiting for something
better. They quickly embraced emerging technologies like LEDs for all the same
reasons Earth-bound producers have: they’re energetically efficient with little
waste heat all in a compact design. This lighting design and strict need for
density meant NASA also found itself on the frontier of vertical farming
Experiments in astroculture, of growing plants in space, mostly
boil down to understanding plant function in microgravity. Be this on a
shuttle, station, Luna, or Mars, all locations exert less gravitational force
than the Earth.
In 1982 Arabidopsis was successfully grown seed-to-seed in
space then germinated back on Earth. This was proof of concept, plant life off-planet
was possible. But the success rate was only about half, and all with a simple,
model plant. This is like sending mice into space before chimps or humans. Subsequent
experiments of greater scope found microgravity seriously impedes and sometimes
even alters plant physiology.
Now, let’s talk about carbon dioxide for a second. Plants
breathe the air, just like us, but they’ve got a use for CO2: it
plays a key role in photosynthesis. Atmospheric enrichment of CO2 within
closed production environments has been practiced since the 1970s. A limited
set of experiments in 1989 found CO2 supplementation also improved a
great number of factors in microgravity. But this might not be so
groundbreaking or critical to astroculture. This is still well before the
current field of controlled environment agriculture had developed. We now see
carbon dioxide as key to increasing plant growth but also recognize a number of
other inherently limiting factors within artificial environments. Put shortly:
most plants, on terrafirma or in outer space, do better with
What has emerged as uniquely problematic in microgravity is
irrigation. Maintaining a reliable range of moisture in the root zone has
become the critical adaptation of astrocultural production. I’m sure we’re all
familiar with water adhesion and its surface tension. On the planet’s surface,
adhesion and tension are frequently dwarfed by the force of gravity itself.
This pulls water into the soil, pulls water through the soil, and actually
plays a large part in the water cycle itself. In microgravity, adhesion and
tension begin to exert their dominance. It’s difficult to direct and instead
will cling to most surfaces it touches. So when water is applied to the root
zone, it clings to the roots. Many plants end up anoxic: they’ve drowned in
their flooded conditions.
The latest developments are using porous tubes and/or plates
to slow the delivery of water and nutrients. It seems like, if we can’t stop
water from coating everything it touches, the plan is to greatly restrict its
flow and access to non-target areas. A slow osmosis via a clay pipe works as a
bottleneck to prevent drowning.
In the early 2000s on board the International Space Station,
astronauts successfully completed two generations–that’s seed-to-seed,-to-seed—of
soy: Space Seeds™. Ok, they’re not really trademarked, but it’s fun to call
them ‘space seeds.’
On August 10, 2015, NASA astronauts were officially allowed to eat space-grown produce for the first time: some leaves of lettuce.
In addition to innovative irrigation control techniques, the
latest astrocultural experiments have just recently begun to increase in scale.
The first growing
area, in 1971, was a mere 10cm2. Little gains were made until 2014 when
they achieved 1700cm2 of production area by using an ‘inflatable’
model which astronauts assembled once in outer space. The latest plans utilize
a vertical racking system and aim for a full square meter (10,000 cm2).
Well, that’s a lengthy enough primer on growing plants in space. There’s plenty more to be told and a wealth of discoveries yet to be made. If you’re interested in some further reading, perhaps try some of these options.
As an ecologist who studies garden systems, the increasing use of native plants in urban and suburban landscaping is exciting to me (see lab member Signe Danler’s great blog post on “ecological gardening”). Unfortunately, there are still many challenges associated with growing the adoption of native plants by home gardeners, with the largest barrier simply being the lack of availability of these species. I have noticed this barrier when giving talks to the public – many home gardeners are interested in gardening with high-ecological value native plants, but don’t know where to purchase them. These anecdotal observations are backed up by peer-reviewed literature, as several studies that have investigated the use of native plants in urban landscapes identified availability as one of the major barriers to adoption.
So, if you are a gardener in Oregon interested in gardening with native plants, where do you start? The good news is that native plants are available! Most big box stores (like Home Depot) have few to no native plants. One option is to go to a large, diverse nursery, like Portland Nursery or Garland Nursery in Corvallis. Besides perusing the selection of native plants they do stock, you can always ask them if they are able to stock a native plant you are interested in. These nurseries generally have contacts with a variety of growers, and demonstrating demand for native plants may lead to nurseries stocking more of these species on the shelf.
But what if you don’t have a specific native plant in mind, or what if you are new to the native plant world? Your best bet is to go to a specialty native plant nursery. Luckily, in Oregon there are a variety of native plant growers throughout the state. Below is a (non-comprehensive) list of some of the retail options. Keep in mind that some of these nurseries grow/stock a wide variety of species, while others specialize in plants of a certain region of the state or in a certain type of plant (think trees, or shrubs). I did not include nurseries that are primarily wholesale operations.
Finally, another great source of native plants are native plant sales! Many Master Gardener chapters and many soil and water conservation districts put on native plant sales in the spring. Here are a few, but check with these organizations in your county and see if they have sales scheduled!
This entry is from Isabella Messer, an undergraduate horticulture student at Oregon State University. It highlights a common Oregon pollinator.
Halictus ligatus covered in pollen from the Morris Arboretum.
Halictus ligatus(Say, 1837), otherwise known as the Mining Bee and which can be classified as a Sweat Bee, are charming little(7-10mm) pollinators who are essential to our success as gardeners and farmers. These little generalists can be found worldwide in temperate climates with over 330 species recorded, so it would be no surprise if also you see them in your garden(1).
Halictus as a genus is very diverse in appearance with colors ranging from metallic greens, blues and sometimes even purple(2). Mining bees on the other hand, can be identified by their small dark brown or black bodies with well-defined yellow or black bands around their abdomens(3). Many of the females but no males will have scopa, which are long dense hairs on their hind tibia for carrying pollen(2). While they may not be the most flamboyant in their genera, their bodies are metallic and sparkle in the sun, giving them an understated but undeniable charm.
H. ligatus on an unidentified flower.
As their name suggests, Mining Bees build their nests underground and the Halictus gendera can demonstrate a very diverse gradation of social organizations within their nests(4). These organizations can range from solitary, communal, semi-social or eusocial(4).
If you are looking to attract some of these lovely and helpful pollinators to your gardens, be sure to leave a sunny and loose patch of soil close to some of your flowers available. Seeing as Mining Bees are broad generalists, there is no need to plant specific flowers or herbs to attract them. They will be beneficial for all of your flowering plants.
Buckley, K., Nalen, C. Z., & Ellis, J. (2011, August). Featured Creatures: Sweat or Halictid Bees. Retrieved April 30, 2018, from http://entnemdept.ufl.edu/creatures/misc/bees/halictid_bees.htm
Elliot, L. (2005, April 8). Species Halictus ligatus – Ligated Furrow Bee, Halictus (Odontalictus) ligatus. Retrieved April 30, 2018, from https://bugguide.net/node/view/14566
Potts, S., & Willmer, P. (1997). Abiotic and biotic factors influencing nest-site selection by Halictus rubicundus, a ground-nesting halictine bee. Ecological Entomology,22(3), 319-328. doi:10.1046/j.1365-2311.1997.00071.x
Rehan, S. M., Rotella, A., Onuferko, T. M., & Richards, M. H. (2013). Colony disturbance and solitary nest initiation by workers in the obligately eusocial sweat bee, Halictus ligatus. Insectes Sociaux,60(3), 389-392. doi:10.1007/s00040-013-0304-8