You know about butterflies, about bees, beetles, and ladybugs, all of our favorite garden critters – but do you know about the parasitic wasp? Alias: The Parasitoid. Not quite a parasite and not quite a predator, they are the zombie-creating hymenopterans that make your garden their home and hunting ground. Unlike a true parasite, the parasitoid will eventually kill its host, but unlike a true predator, there is a gap between parasitism and host death. The Parasitoid is truly one of a kind, but with thousands of species in over 40 families, there are many of that kind. They prey by laying their eggs in or on the bodies and eggs of other arthropods, growing, aging, and getting stronger as their unknowing host provides their executioner food and shelter until the parasitoid is ready to attack.
As menacing as their way of life may seem, parasitic wasps are actually one of the most effective biological pest control agents available to home gardeners, and can be an excellent indicator of habitat health for ecologists. As biocontrol agents, parasitoids can effectively manage a very wide variety of pests from aphids and sawflies to weevils and mites, along with many more. They occur naturally if their hosts/prey and habitable conditions are present and it costs little to nothing to maintain their populations. If pest outbreaks are not completely out of control and the site is habitable, parasitoids can safely, easily, cost-effectively, and naturally bring pest populations below economic injury thresholds. Know any pesticides that check all those boxes? In terms of habitat health, parasitoids can drive biodiversity and positively influence ecosystem functions. As such, their diversity and abundance can act as an indicator for the overall health and functionality of an ecosystem – such as your home garden.
Is it starting to seem like parasitic wasps could be an area of research for say. . .a garden
ecology lab? Certainly seems like that to me. That’s why this upcoming year I will be taking on an undergraduate research project to assess the parasitoid populations present in the Portland home gardens Gail and I have collected bees from for the last 3 years. Thanks to our sampling methods, we already have lots of parasitoid data to perform this analysis with, so there won’t be any more soapy bowls in your gardens this summer. This is the first of hopefully many blog posts that will accompany this research, so stay tuned as the year progresses to learn more about your new flying friends!
Further Reading and References:
Video showing some parasitoid activity:
Natives vs Nativars Recent studies report an increase in consumer demand for native plants, largely due to their benefits to bees and other pollinators. This interest has provided the nursery industry with an interesting labelling opportunity. If you walk into a large garden center, you find many plant pots labelled as “native” or “pollinator friendly”. Some of these plants include cultivated varieties of wild native plant species, called “nativars”. While many studies confirm the value of native plants to pollinators, we do not yet understand if nativars provide the same resources to their visitors.
Photo Source: Moxfyre – Own work, CC BY-SA 3.0,
E. purpurea ‘Secret Passion’
Photo source: National Guarden Bureau
An Echinacea Example Above are three purple cone flower (Echinacea purpurea) plants: on the top is the wild type, in the middle is a nativar ‘Maxima’, and on the bottom is another nativar ‘Secret Passion’. In some cases, like ‘Secret Passion’s double flower, there is an obvious difference between a nativar and a wild type that might make it less attractive to insect visitors. Since we can’t see the disc flowers (the tiny flowers in the center of daisy family plants), we might assume that ‘Secret Passion’ may be more difficult for pollinators to visit. The floral traits displayed by ‘Maxima’ seem similar to the wild type, but it might produce less pollen or nectar, causing bees to pass over it.
Unless we actually observe pollinator visitation and measure floral traits and nectar, we can’t assume that natives and nativars are equal in their value to pollinators.
Nativar Research One study looking at the difference between native species and their nativar counterparts has come out of the University of Vermont (my alma mater!). A citizen science effort started by the Chicago Botanic Garden is also currently ongoing. My Master’s thesis will be the first to use a sample of plants specific to the Pacific Northwest. We have selected 8 plants that are native to Oregon’s Willamette Valley and had 1-2 nativars available. These plants have shown a range of attractiveness to pollinators (low, medium, or high) based on Aaron’s research. We are including plants with low attractiveness because it’s possible that a nativar may have a characteristic that makes it more attractive, such as a larger flower or higher nectar content.
Experimental Design We have four garden beds in our study, and each bed contains at least one planting of each native species and their nativar counterpart(s). This kind of design is called a “Randomized Complete Block” (RCB). The RCB has two main components: “blocks”, which in our case are garden beds, and “treatments”, which are our different plant species. Above I have drawn a simplified RCB using two of our plants: Camas and California poppy. The bamboo stakes outline each plot and have attached metal tags that label the plants.
We planted our seeds and bulbs in November and will plant out 4″ starts of the other plants in early Spring. Look out for my spring and summer updates to see how these plots progress from mulch and bamboo stakes to four garden beds full of flowers and buzzing insects!
This week’s post comes from Mericos Rhodes, who is a MAIS student at Oregon State University. His M.A. studies combine the fields of Horticulture, Food in Culture and Social Justice, and Public Policy Mericos’s capstone thesis will be comparing the history, practices, philosophies, available research funding, and scientific basis of four agricultural approaches: biodynamic, permaculture, organic, and regenerative farming. Mericos is a farmer, himself. He’s also a deep thinker and eloquent speaker and writer. We think about farming in two very different ways: I am more of a scientist and he is a practioner and an artist. I look forward to our conversations, because I always broaden my perspective after talking with Mericos. He’s truly been a delight to have in the lab. (-Gail-)
What does the word ‘permaculture’ mean, to you?
Maybe ‘permaculture’ brings to mind an herb spiral, with rosemary, thyme, and some basil crowning it in summer. Or you may envision intricate systems of swales, which slow down and carry water to ridgelines. Maybe it’s as simple as letting ducks into an orchard. Or maybe ‘permaculture’ means nothing to you, at all!
Well, permaculture is most definitely a thing. Yet it’s a slippery thing, a concept full of emergent behaviors and biodiverse adaptation, unsuited to singular, rigid definition. Permaculture has been growing “from the bottom up,” and its distributed growth takes as many forms as there are watersheds on this planet. Indeed, one of the difficulties of defining permaculture is due to its fundamental principle that no particular crops, tools, or techniques are universally beneficial, for land management and food production. Learn your land. Learn its quirks, its frost pockets, and its native flora and fauna. Let what you learn guide you. Of course, following these principles will lead to vastly different techniques and plantings, across the world’s different ecosystems.
Unlike “conventional” industrial, yield-driven modern agriculture farms, no two permaculture farms will look alike. Even the cultural trappings of permaculture affirm this diversity: instead of “conferences,” permaculture people gather in “convergences,” to share evolving ideas and practices.
The distributed, evolutionary, informal nature of ‘permaculture’ makes it a nightmare for rigorous research. During my very first conversation with Dr. Langellotto, she brought this up. My application letter had mentioned an interest in applying permaculture to broad-scale agriculture. Just seeing “the P word” made her wary, she said. Luckily, my interest wasn’t a deal breaker, it was an inspiration: Dr. Langellotto suggested that I direct my interdisciplinary research towards defining permaculture in a way that researchers could use to study it.
So part of my inquiry is a simple question with a complex answer: “What is permaculture?”
Along with permaculture, i will also be examining organic and regenerative farming. ‘Organic’ has been codified by the USDA, a process that has directed more funding, research, and legitimacy to that type of farming, but has diluted the whole concept, in the eyes of many elder organic farmers. ‘Regenerative’ is a newfangled, five syllable word that seems to refer to farm practices that actively build soil health, rather than depleting or even simply maintaining it. The word is tossed around more and more, with relative impunity.
Can we create a system that defines, legitimizes, stabilizes, and preserves the spirit of ‘regenerative,’ in a way that ‘organic’ no longer does, for many farmers and ecological eaters? Is that possible for permaculture? That’s the hope, and the motivation for my studies.
If all of this sounds more qualitative than the research that you may expect from a horticulture department, that’s because it is! However, I am loving being a part of the Garden Ecology Lab, and the Horticulture department, because the plant and insect-focused research being undertaken by my peers constantly grounds me. All of these types of agriculture and land management are, after all, just different ways of interacting with plants, animals, and soil. My hope is that my presence here may inspire those who think so beautifully about horticulture and all of its related fields to deeply consider how our work affects the biodiversity of life on this planet, climate change, and the role that our human species can play in healing the Earth.
For my dissertation research, I am studying which native Willamette Valley wildflowers are most visited by pollinators and natural enemies for use in home gardens and urban landscaping. I’ve previously shared preliminary results from my field study on our blog, namely pollinator abundance and richness. For a refresher, here are summaries from 2017, 2018, and 2019.
Determining which of these flowers are most attractive to insects is only half of the equation — I also want flowers that are attractive to gardeners. To investigate this I developed two surveys — thanks to anyone reading who took them! The first simply asked gardeners to rank the aesthetic appeal of my study plants, as well as how likely they would be to utilize them in their home gardens. This allowed me to get a baseline understanding of how appealing these flowers are for use in home gardens and landscaping.
As you can see in the figure below, many of the plants most visited by bees (highlighted in orange) were the least attractive to gardeners (Fig. 1), while plants gardeners liked the most (e.g. Iris, Columbine) were hardly visited by bees. However, its notable that many of these native wildflowers ranked around a four on a 1-5 scale, showing that these flowers do have a high potential appeal for use in landscaping!
Figure 1: Gardener ranked aesthetic appeal of study flowers on a scale of 1-5. Orange bars note plants that were consistently highly visited pollinator plants. N=587
The follow-up survey consisted of a subset of ten flowers most visited by bees, and again asked respondents to rank the aesthetic appeal and likelihood of planting for each of these flower species. Then, they were shown facts about and images of bees that visit each flower species, and asked whether they viewed each plant species more favorably, less favorably, or the same. Finally, they were asked to re-rank how attractive they found the flower species and how likely they would be to use the species in their garden, both on a scale of 1-5.
This second survey showed a remarkable increase in gardener acceptance of pollinator friendly native plants after being educated on plant-pollinator associations. Over 80% of respondents stated that they viewed Clarkia amoena as more attractive after gain, and over 60% of respondents viewed Phacelia heterophylla, Madia elegans, and Gilia capitata as more attractive (Fig. 2).
Figure 2: Percent of respondents viewing flower species as more attractive after learning about pollinator associations. N=184.
Likelihood of planting
After learning about the benefits these flowers provide to pollinators, gardeners were also more likely to plant all ten flower species (Fig. 3). Notably, they were 40% more likely to plant Phacelia heterophylla, (a species that ranked as the least aesthetically appealing overall in the first survey). As a whole, they were also over 20% more likely to plant Solidago canadensis, Clarkia amoena. Similar increases were also observed in likelihood of planting Oreganum vulgare and Nepeta cataria. Many of the plants that showed a smaller percent change are species that started out with a higher aesthetic appeal (e.g. Gillia capitata, Lavendula intermedia, Aster subspicatus), meaning gardeners were already very likely to include these plants in their home garden before learning about the ecological benefits they provide.
Figure 3: Percent change in respondent’s likelihood of planting each top pollinator flower after learning about the pollinators associated with each. N=184
What does this all mean? This suggests that although native plants are frequently denounced as being less attractive than showy garden species, many home gardeners are still willing to use native flowers in their landscaping. Additionally, this lends credence to the concept of “ecological beauty” – that many gardeners are willing to utilize plants that will increase the habitat value and wildlife diversity in their yards.
This post comes from Cliff Brock, who is a graduate student in the Contreras (plant breeding), Langellotto (pollinators), and Lambrinos (invasive plants) lab groups. Cliff is studying the impact that plant breeding has on invasiveness and pollinator visits in butterfly bush (Buddleja davidii) and its cultivars. Having three co-advisors can be extremely challenging. However, Cliff has been a true joy to work with, and seems to have navigating the complexities of three labs, quite well.
Cliff decided to write about flies as pollinators. When I asked him why he wanted to write about flies, he mentioned that they usually pollinate flowers that have foul smells, or that may not be as attractive as other flowering plants. He said that he has a special place in his heart for these ‘botanical underdogs’ ~ a sentiment that I thought was sincerely sweet.
While bees deservedly get most of the attention regarding their pollination services, many of our most important crops and wildflowers are primarily pollinated by flies. Generally speaking, fly-pollinated flowers are dark maroons to reds and emit earthy, fermented, or putrid aromas. The coevolution of plants and flies has resulted in some of the most amazing and unusual flowers. The largest flowers in the word, Amorphophallus and Rafflesia, are almost exclusively pollinated by flies and beetles.And even our beloved chocolate requires a small midge fly for its sole pollinator.
Here in the US, many of our most beloved spring ephemerals have coevolved with flies. While many Trillium are bee pollinated (e.g. the abundant white Trillium ovatum), species with red and brown flowers are primarily pollinated by fungus gnats. The iconic American pawpaw (Asimina triloba), which has seen a resurgence in popularity, smells of rotting flesh and is irresistible to a whole host of fly species.
Asarum, or wild ginger, is a generally diminutive herbaceous plant often grown as a groundcover. The odd flowers are born close to the ground and are usually hidden from human view. Yet I find them particular beautiful, and every year I look forward to rediscovering them beneath the mottled foliage. Asarum takes fungal mimicry to a new level. Panda ginger, one of the Asian species, is especially funky. The flowers mimic the colors, textures, and smells of toadstools.
What’s next in urban agriculture is going to take place in the cityscape we’ve all heard described before: two-thirds of the world’s 10 billion people will be living in urban areas—mostly across 40 or more mega-cities around the globe—by the year 2050. You’re probably bracing yourselves, waiting for either a list of depressing facts or some ‘hail Mary, technology can save us all’ kind of talk.
Not today. Today we think of green pastures amid concrete jungles.
Urban agriculture is the production, processing, and marketing of produce based on living systems from the land or water located throughout urban and peri-urban areas. Anyone cropping food, flowers, fiber, feed, or herbs from their corner of their city is engaging in a small-lot, local agriculture with an utterly minimized transport chain from grower to eater. These green, vegetative, productive spaces within city landscapes can provide valuable ecosystem services: floral habitat for pollinators, stormwater management, and even mediating the temperature extremes of urban heat islands. People often find urban gardens foster cross-cultural and multi-generational spaces for social interaction. These disparate green spaces, however small each might be, aggregate to large areas across metropolitan regions. A conservative 20 acres of urban gardens in Portland, Oregon, fifty-one acres in Chicago, Illinois, and a whopping 120 acres in Madison, Wisconsin!
More good news: these growing plots don’t stop at the hobby level. Across the United States, counties with significant urban encroachment also produce the lion’s share of fruits, nuts, berries, and vegetables, as well as accounting for most of the farm-gate value of these goods.
But now we come to a bit of bad news, unfortunately. Because while these urban-adjacent farmlands produce the most food in the most high-value agricultural markets, their days are numbered. While not as romantic as the Amazonian forests, some of the most fertile land across this country is being consumed and paved over by sprawling cityscapes. This plight is common due to a mismatch between those who own deeds to land and those who seek the land’s productive agricultural use. Countless urban spaces have seen their productive days ended when the land became valuable enough for someone to decide to sell it off for development.
This is relevant to us today because growing food within the cities themselves is one of the easiest ways to increase our resilience against disruptions to our modern, industrialized food supply chain. Just as victory gardens stabilized many citizens through global wars, we too can use our land and our labor to renovate vacant land in shrinking cities like Baltimore, Cincinnati, Philadelphia, Detroit, and the others which are sure to follow the implosion of the last economic boom.
New American farmers—entrepreneurs all—are literally working overtime to access the new niche markets which are springing up across modern urban centers. They’ve surveyed the future and invested in becoming extremely specialized producers of fine agricultural goods. To me, that sounds like taking quite chance: betting it all on a small market with few, discerning clients.
But we might gain some of their confidence if we examine some of their assumptions. Barring extreme, world-altering scenarios like an extinction-event asteroid impact, human population in 2050 is pretty well guaranteed at this point. It’s only thirty years away and average birthrate is not quickly changing. This also means we can be pretty secure in the assumption of continued urbanization. The current population density alone is enough to birth enough humans to further compound the growth of urban centers. This makes the relevance of things like tele-commuting more a question of degree of urban density and sprawl growth. Lastly, many farmers are seeing their emotional investment in the quality of food finally reflected in public policy.
A proposed “new food equation” predicts the end of ‘cheap food’ as global calorie production has been secured. The focus is now changing to include quality, or the nutritional content of foodstuffs. Nations recognize that food production remains a matter of national security in a number of ways. First as a matter of imports and exports. Self-sufficiency means not relying upon another nation to feed your populace. Excessive production enables exports which not only enrich a nation but can operate as the same leverage which is being avoided in the previous example. Lastly, public officials and private people are beginning to attribute more health complications and costs to dietary factors like obesity or malnutrition.
New urban farmers are exploring many novel approaches to urban agricultural production. Controlled Environment Agriculture (CEA) is taking protected cultural growing techniques and implementing them using modern technology. Managers can adjust a whole palette of environment controls: light, temperature, precipitation, atmospheric composition, hormonal regulation, and genetic alteration.
This is made possible largely due to advances in microelectronic technology. Light-emitting diodes (LEDs) have drastically slashed the cost AND increased the efficiency of artificial lighting. Cost-effective LEDs have revolutionized indoor production like plastic sheeting did for field production. And with the decreased cost of indoor production comes increased innovation as more minds are able to devise feasible plans to grow something worthwhile in artificial conditions. Some of these ideas look to the world’s growing demand for protein and consider growing plant-protein for lab-burgers whiles others simply aim to minimize their livestock and grow insect-protein.
How can someone possibly stay abreast of all these developments? I feel like I’ve listed too many, and yet for each example in this text there are a dozen which could not be included. Well, the first way is to get directly involved! Find and become a part of something in urban agriculture. If you’re in relevant circumstances you’ll need to expend less energy trying to stay informed as this will simply become a common topic of your conversations. You could also set up some phrases to trigger a news-aggregator to your inbox. Look for topics relevant to new urban farming. I reiterate my point about protein production: it’s going to be big at some point and the innovation is going to be discovered by a small operation facing unconventional challenges. While it’s cliché and tastes like papier-mâché to say: apps! Seriously, be on the lookout for apps which facilitate the work of small farmers. If there’s ever going to be a mass mobilization of people into agriculture, then we need to simplify and systematize as much as we can. Trust me, most of them will feel fine if they’re no longer forced to wear so many hats.
If you’re still interested, you might benefit from investigation into various topics which have been extensively researched and greatly overlap with many facets of urban agriculture. Cuba’s organopónicos system demonstrates the practical success of urban food production when actively pursued by many people and policies. The Netherlands have led global greenhouse production for years, and they continue to innovate and push the boundaries of protected and synthetic production environments.
Space! The final frontier. It’s exciting, isn’t it? I’m excited even just to say the word. I really did shout it out just then. I’m dreaming of going to space one day, how about you? Anyway, astronauts are experimenting with plant growth and crop production in space. It’s all quite enthralling, but too much for this post. If you’d like to know more, keep an eye out for my next post in a couple months!
Further research options:
An article from National Geographic about how The Netherlands ‘feed the world.’ Especially interesting is the third picture showing vertical production of chickens.
An all-encompassing chapter regarding urban soils, from my most favored author on the subject: Pouyat et al., 2010.
A podcast episode about urban growers in early New England who are called “The Diggers.” I suggest starting at either 40 seconds in or at 3:20, then listening through to at least 12:15.
Every June – August, from 2017-2019, we collected bees from 25 Portland area gardens. As I start to build out a Bee Guide for Portland Gardens, I wanted to highlight some of the notable bees that we collected. We are still waiting for our 2019 bees to be identified. The details, below, are for bees that were collected in 2017 and 2018 and identified by Sarah Kornbluth (2017) or Gabe Foote (2018).
We collected five species of bee in the genus Megachile:
- Megachile rotundata (2 females and 1 male)
- Megachile angelarum (8 females and 5 males)
- Megachile perihirta (1 female)
- Megachile fidelis (3 females)
- Megachile centuncularis (1 female)
Worldwide, Megachile bees are extremely diverse: an estimated 1,400 species of Megachile bees can be found, globally and an estimated 140 species of Megachile can be found in the United States. These bees are in the Family Megachilidae, which includes the leafcutting (e.g. Megachile species), mason (e.g .Osmia species), and wool carder bees (e.g. Anthidium species). In the family Megachilidae, females carry pollen on their abdomen.
In this post, I wanted to cover Megachile fidelis, Megachile perihirta, and Megachile angelarum.
|Megachile angelarum||Native||Generalist (Prefers Lavandula, Perovskia, Vitex)||Solitary||Cavity|
|Megachile fidelis||Native||Generalist (Prefers Asters)||Solitary||Cavity|
Megachile angelarum was the most common bee in this genus that we collected from Portland area gardens.
Diet: Although this species has been collected from a broad array of floral hosts (see list from Discover Life), Frankie et al. (2014) note that this species prefers lavenders (Lavendula), Russian sage (Perovskia), and chaste tree (Vitex).
Sociality: This species is solitary, which means that each individual female builds her own nest, collects nectar and pollen to provision her young, and lays her own eggs. In bees with advanced social structures, such as honey bees, the workers collect nectar and pollen to feed the young, and the queen lays the eggs. Solitary bees die soon after they build their nest, load nest cells with pollen and nectar, lay their eggs, and seal the nest cell shut. Many solitary bees may nest in close proximity to each other. Thus, solitary bee doesn’t mean loner bee; it means that the female does all of the work on her own, without cooperation or collaboration from other bees in her species.
Nesting: Megachile angelarum nests in cavities. Rather than cutting leaves, females collect resins and gums to partition nest cells. Since this bee does not cut leaves, it lacks teeth on its mandibles, unlike other bees in the genus. The bee has been found in drilled pine wood (10cm deep holes, 0.5 cm in diameter; Dicks et al. 2010). Other studies have found this species in nest blocks with a 3/16th hole size (Galasetti 2017).
Appearance: Like many bees in this genus, it is a robust-sized bee, with females typically spanning 10-11 mm in length and males a bit smaller, at 8-9 mm in length. The lack of teeth and cutting edges on the mandibles can be helpful for identification.
Notes: Across 2017-2018, we collected this bee from seven different Portland area gardens, or nearly 1/3 of our sampled gardens. Megachile angelarum is likely parasitized by another bee, Stelis laticincta. Stelis laticincta is a social parasite, or cleptoparasite of other bees. What this means is that Stelis laticincta invades the nest of another bee, and lay their own eggs, just as cuckoo birds do with other birds. Once the Stelis laticincta eggs hatch, the larvae kill the Megachile angelarum larvae, and eat the pollen and nectar provisions that have been provided by the Megachile angelarum mother.
We collected a single Stelis laticincta in 2017-2018, and it came from a garden where we collected four Megachile angelarum specimens. Having a healthy Megachile angelarum population increases your chances of having more bee species, by supporting cleptoparasites, such as Stelis laticincta.
Megachile perihirta is commonly known as the Western leafcutter bee.
Diet: This bee is a generalist, and will collect nectar and pollen from many different types of flowering plants.
Sociality: Solitary (see notes for M. angelarum).
Nesting: Unlike many Megachile bees, this species does not nest in cavities, but instead digs shallow nests in the soil (Frankie et al. 2014, page 102). I had thought that all bees in the genus Megachile were cavity nesters. (Actually, I thought that all bees in the family Megachilidae were cavity nesters). But, Eickworth et al. (1981) report that soil excavation was widespread in the family Megachilidae and in the genus Megachile.
Appearance: This was the largest Megachile species we collected. Females typically spanning 13-14 mm in length and males span 12-13 mm in length.
I am soooooo sad that we didn’t collect a male of this species! The males have enlarged forelegs, covered with hairs (photos of the males can be found here and here), which the MALES USE TO COVER THE FEMALES EYES DURING MATING!!!! Biologists suggest that this helps to keep females calm and receptive, during mating (Frankie et al. 2014, page 103).
Notes: We only collected a single specimen of this bee. It came from our smallest garden (1,800 square feet in size), in an industrial area of Northeast Portland. And seriously: how cool is it to have a bee species where the mating ritual includes the male covering the females eyes with his super-hairy forearms!!!??
Diet: Frankie et al. (2014) note that this species seems to prefer plants in the Asteraceae, including Aster, Erigeron, Rudbekia, Cosmos, and Helenium). Hurd et al. (1980) note that this species is commonly collected from sunflowers (Helianthus).
Sociality: Solitary (see notes for M. angelarum).
Nesting: This is a cavity nesting bee that tends to occupy larger holes (0.65 to 0.80 cm in diameter (Barthell et al. 1998). Unlike Megachile angelarum, which does not cut leaves or petals to line their nest cells, UC Davis has a great photo of a female Megachile fidelis carrying a piece of Clarkia petal. In his native bee research, Aaron Anderson would regularly find bees cutting neat discs from Clarkia flowers. I wonder, now, if collecting petal discs from Clarkia flowers is characteristic of M. fidelis.
Appearance: This species is another robust-sized bee. Females typically spanning 11-13 mm in length and males span 10-12 mm in length.
Once again, I am beyond bummed that we didn’t collect a male of this species! Males of this species also have enlarged forelegs covered with long hairs, although not as pronounced as in male M. perihirta. Once again, biologists suspect that the males use their hairy forearms to cover the females eyes during mating (Frankie et al. 2014, page 103).
Notes: We collected one specimen from a 0.2 acre, flower-filled garden that is adjacent to a golf course in Canby. The other two specimens were collected from a 0.1 acre, flower-filled garden in Northeast Portland.
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 Short Courses 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 gardeners.
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.
I’m thrilled to announce that this summer I completed the third field season of my study. This is slightly bittersweet – while I’m excited that we are done with hot fieldwork, I will miss chasing bees around the farm and the view of Mt. Hood. I’m incredibly thankful for this third season of data, as it will help account for some of the temporal variation inherent in ecological studies. In fact, pollinator communities in particular tend to be highly variable both within and across field seasons. Having three seasons of data will hopefully allow us to identify more reliable patterns of pollinator visitation between my study plants.
Lots of lab work remains, as I’m tackling the insect samples that we collected with the bee vacuum. With the help of a dissecting scope, I’m attempting to identify the each specimen to at least the taxonomic level of family to get a sense of the broader insect communities associated with each flower species in my study. It will be several months before I can share this species-richness data, but in the meantime I have bee abundance data to share with you!
As a refresher, we performed timed pollinator observations at each plot. This consisted of observing each blooming plot for five minutes and counting all the insects that landed on open flowers. Bees were sorted to “morpho-type” (honey bee, bumblebee, green bee, and other native bee). Though this doesn’t give us species-level information on the floral visitors, it allows us to understand which plants attracted the most pollinators overall, and allows us to detect any patterns of visitation between honey bees, bumblebees, and solitary native bees. Below is a summary of some of the highlights.
2019 overall bee abundance by plant species:
- Origanum vulgare, Lavendula intermedia, and Eschscolzia californica were top five bee plants in 2019, just as they were in 2018.
- In 2019, Phacelia heterophylla and Solidago canadensis jump into the top five, while Nepeta cataria and Gilia capitata fall out of the top five. It should be noted that Nepeta was the sixth most attractive plant, with about the same visitation level as Solidago.
- Again, similar to 2018, it appears that honey bee visitation was driving the high visitation rates of the popular exotic garden species (marked with a red asterisk), while native wildflowers were being visited more frequently by native bees.
- I’ve included the 2017 and 2018 overall abundance graphs as well, for comparison. You can see that the overall abundance was higher in 2019 for the two most popular plants, at about ~25 bees per observation period!
2017 overall bee abundance by plant species:
2018 overall bee abundance by plant species:
Since honey bee visitation drove the high abundance of many of the top pollinator plants, I took honey bee visits out of the data set and made a new graph, to compare which plants were most attractive to native bees.
2019 native bee abundance by plant species:
As you can see above, honey bees are excluded from the analysis, the top five most popular plant species completely reshuffles.
- Native wildflowers Phacelia heterophylla, Eschscolzia californica, and Solidago candensis are still top pollinator plants, while Aster subspicatus and Anaphalis margaritacea jump into the top five.
- The exotic garden plants fall in the rankings: Lavendula intermedia drops to the middle of the pack, while Nepeta cataria and Origanum vulgare hardly attracted any native bees at all (an average of only ~one bee per five minute observation).
- Phacelia heterophylla, Lavendula intermedia, and Eschscolzia californica attracted the most bumblebee species.
I’ve included that 2017 and 2018 native bee abundance data below for comparison.
2017 native bee abundance by plant species:
2018 native bee abundance by plant species:
Please stay tuned for more updates on the bee species richness we collected in 2019, as well as data on the other insects (pests and natural enemies) that we collected!
Although I have been studying garden bees for the past three years, I was never focused on honey bees. From a biodiversity point of view, they are not very interesting to me. They are non-native and abundant. In fact, honey bees were the most abundant bee species that we collected in Portland-area gardens (332 individuals collected), even though we took great care not to collect more than one individual per visit, when hand-collecting.
Honey bees, which hail from Europe, are only one of 20,000 bee species, worldwide. In North America, there are 4,000 species of bee. In Oregon, we have between 400-500 species of bee. From Portland area gardens, we have documented 86 species of bee (with our 2019 bees still awaiting identification).
Unlike some native bees, honey bees are not at risk of extinction. Compare this to bumblebees. We found 17 species of bumblebee in Portland gardens, two of which (12%) are at risk of endangerment or extinction, due to declining populations: Bombus fervidus and Bombus caliginosus. Across North America, more than 25% of bumblebee species are thought to be at risk of extinction.
By focusing ‘save the bee’ campaigns on honey bees, we may be neglecting the bee species that really need our help. In fact, researchers have started to call out organizations and advertising campaigns that promote feel good stories about honey bee conservation as a form of ‘bee washing’. You can visit www.bee-washing.com to learn more about companies that promote their product or organization as being bee-friendly, in a less than genuine way.
Researchers have documented at least seven different ways that honey bees may harm native bee species (summarized in Cane and Tepedino, 2016):
- Honey bees monopolize and deplete nectar and pollen from local plant communities, which can reduce native bee reproduction.
- By depleting local plant resources, native bee females have to devote more time and energy to fly and find new resources, which also reduces native bee reproduction.
- Unlike honey bees, most bees are solitary, which means that they do not live in colonies and they do not have a queen. Solitary females who have access to fewer floral resources produce fewer daughters and more sons. Since female bees are needed to maintain a population, this skewed sex ratio can slow population growth and recovery in native bees.
- When females collect less nectar and pollen, they have less food to feed their young. These bees grow up to be smaller, and are more likely to die over winter, compared to well-fed bees.
- The longer a solitary bee mom is away from her nest, the higher risk that parasites and predators will attack her unguarded young.
- Honey bees can physically block native, solitary bees from preferred pollen hosts.
- Honey bees have many diseases. Some honey bee viruses have been found in native bee communities. Researchers think flowers that are visited by both native bees and honey bees are analogous to an elementary school water fountain: a place where repeat visitors can pick up a pathogen.
Please note that I am not suggesting that you extinguish honey bees from your garden. What I am asking, instead, is that you take the time to learn about and to notice some of the other 80+ species of bee that you might find in your garden. My group is creating a ‘Bees of Portland Gardens’ guide that we hope can help you in this journey. In the meantime, there are some great guides that are currently available. One is Wilson and Carrill’s ‘The Bees in Your Backyard: a guide to North America’s bees’. This book is available at Powell’s City of Books, as well as on Amazon. The second is August Jackson’s ‘The Bees of the Willamette Valley: a comprehensive guide to genera’. This free guide can be found online.
The first step to saving something you love is to be able to recognize it and to call it by name.
- Cane and Tepedino. 2016. Gauging the effect of honey bee pollen collection on native bee communities. Conservation Letters 10: 205-210.
- Jackson. 2019. The Bees of the Willamette Valley: A Comprehensive Guide to Genera. Self-Published, Online: https://tinyurl.com/y4qfssrl.
- Wilson and Carrill. 2016. Bees in Your Backyard: A Guide to North America’s Bees. Princeton University Press.