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.
Parasitoid laying eggs in stink bug eggs. Photo Courtesy of Christopher Hedstrom
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
A Parasitoid collected from a Portland Garden in 2017 during the Garden Pollinator study
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!
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.
Bee Species
Origin
Diet
Sociality
Nesting
Megachile angelarum
Native
Generalist (Prefers Lavandula, Perovskia, Vitex)
Solitary
Cavity
Megachile perihirta
Native
Generalist
Solitary
Soil
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.
Megachile angelarum female.
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.
Megachile angelarum. The mandibles are a bit hard to see, by they are in the lower portion of the face. Note that there are no teeth, or serrated edges on the mandibles, which is a characteristic of this bee.
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.
Megachile perihirta female.
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!!!??
Megachile fidelis
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.
Megachile fidelis female.
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.
My name is Mykl Nelson, a world citizen intent on feeding the globe.
The first distinct connection to food I remember was in the late 90s while living in İzmir, Turkey. We had a large mulberry tree in our yard which bore delicious fruit. I also remember the bazaar in the Buca province. Cart after cart of people selling mounds of all manner of produce. After leaving Turkey, and for maybe half of my childhood summers, I lived on the farm of my paternal grandparents’ in Worland, Wyoming. I saw many aspects of high, dry farming of row crops: sugar beets, alfalfa, barley, and dent corn. I could only catch fleeting glimpses into the life of my grandfather, a commodity farmer. But in my recent years I’ve been openly told that these American farmers vehemently hoped their children were “too smart to get into farming.” Their wish came true. Of four children and nine grandchildren, I’m the only one in agriculture.
I turned on to agriculture when a friend and I built a 400 square-foot poly-tunnel in our backyard in Colorado. We didn’t know anything more than that we wanted to grow our own food. I remember feeling so incredibly accomplished, fulfilled, and validated picking personal salads straight into dinner bowls. I took that inspiration to fuel my travel to the Pacific Northwest, a place I knew I could immerse myself in the world of tending plants. I pushed every aspect of my network to get more involved in farming and to gain space to garden. I’ve worked on three organic urban farms since moving to Oregon. I went back to school and retrained from political science to agricultural science. I continued my education with a graduate project which firmly oriented my interests to the world of urban agriculture.
I am now an instructor of urban agriculture here at Oregon State University. My current duties are to develop new online courses to train and empower new urban growers to produce food within the confines of their modern environment. This work is challenging, as urban agriculture suffers from a distinct lack of focused research. One of the most relevant discoveries from my graduate research project is that nearly all advice extended to urban growers is simply copied from traditional agriculture. Even if suggestions are altered with respect to the scale and local environment of urban growers, the research supporting these suggestions is still wholly based upon traditional agricultural methods of food production. I am developing my courses with this mismatch in mind. I have changed my approach from seeking to broadly support food production and instead specifically analyze and adapt traditional recommendations to work in an urban environment.
I use scientific research to inform my course development on many levels. At the macro-level, articles like one by Oberholtzer, Dimitri, and Pressman (2014) have reported that most farmers, and new farmers especially, struggle with complications in managing the farm’s business much more than the challenge of growing their crops. I used these findings to inform the outline of a new course that I am developing: Introduction to Urban Agriculture. Rather than spending time covering the how or why of plant growth in much detail, I’ve instead focused on how urban growers can adapt agricultural principles to their unique environment. I strive to keep students aware of how these factors should influence their management activities and always keep the concept of ‘value’ in their mind. On a more micro-level, I have built the lectures regarding soil and plant growth with adaptations of my own previous graduate research.
My method of teaching is heavily influenced by a new wave of teaching research which is well represented by James Lang’s book: Small Teaching. Broadly, this approach suggests frequent review of material as well as a more piecemeal and cyclical approach to teaching topics rather than large chunks of lecture punctuated by intermittent exams. Further, I refuse to accept that an online classroom is limiting. Modern students are demanding more than just lectures laid over powerpoint slides. I am exploring numerous avenues to increase engagement and foster social connection, all facilitated by digital platforms. I expect my courses to provide foundational pillars of knowledge for new urban growers as they pursue OSU’s new and entirely online certificate in urban agriculture. I hope to see every student embark on their own path to grow food within their urban environments. I look forward to reports of former pupils starting and operating successful urban farming businesses.
It’s been a while since I’ve posted a field update about my native plant – pollinator study, so this post will be a recap of the entire 2018 field season! Sampling this year was successful, though it was a much shorter bloom season for almost all the flowers species, perhaps due to a combination of the heat, low rainfall, and lack of supplemental irrigation. I performed some summary statistics on the data, and there are some intriguing results from this year.
Below is a summary of some of the highlights:
Visitation Data
Only two (Gilia capitata and Nepeta cataria) flowers made it into the top-five most attractive in 2017 and 2018. The full results can be visualized in the two histograms below.
Three of the non-native garden species were found in the top five in 2018 (though I noted this visitation seemed strongly driven by honey bees).
2017 overall bee abundance by plant species:
2018 overall bee abundance by plant species:
Because of this, I removed honey bees from the dataset and recreated the graphs.
The 2017 visitation data is largely unchanged (though Nepeta cataria is less attractive, and Eschscholzia californica jumps into the top-five).
When only native bees are considered, the top-five most visited 2018 plants are almost completely different. Eschscholzia californica, Aster subspicatus, and Phacelia heterophylla are the three most attractive flowers.
It seems like the native wildflowers are being visited more frequently by native bees.
2017 native bee abundance by plant species:
2018 native bee abundance by plant species:
Sampling Data
I also take vacuum samples from each plot so that we can identify pollinators (and other insects) to species. I’m excited that my 2017 and 2018 bees have been identified by taxonomist Lincoln Best!
Across those two years, we collected 36 bee species (from 540 samples, which doesn’t include all the honey bee individuals). You might ask – is this many bees, or only a few? Simply put – we don’t know! Without knowing how many bee species are found at our site at NWREC, its hard to tell what this number means. However, I was excited to find that we collected two bumblebees that are on the IUCN Red List, Bombus fervidus and Bombus calignosus.
Below are a two pollinator interaction matrices to visualize these data, but I should note that these are very preliminary – they are not scaled by number of sampling events but are still a neat way to visualize interactions and richness data. (Darker squares represent higher abundance; a white square means no bees were collected off that flower).
Bumblebee Richness and Abundance:
Other Native Bee Diversity and Abundance:
Its obvious from looking at these data that the answer to the question “which plants attract the most pollinators?” isn’t simple! Are we interested in certain suites of bee species – honey bees, or bumblebees? Are we interested in high overall abundance, or high species richness? Some species attract many individuals but few species, while other plants attract a higher species richness but fewer overall individual bees. Additionally, there are also seasonal changes in bee populations to consider, as well as seasonal changes in flower phenology and floral display.
Luckily we’re going to have a 2019 field season, which will help account for this temporal variation and allow us to acquire data for species that didn’t flower in one or both of the previous years.
Our paper on the potential for bee movements between gardens and urban/peri-urban agriculture has been published in a special issue on Agroecology in the City, in the journal Sustainability.
In this paper, we estimated how far the bees we collected from our Garden Pollinators Study could move between gardens and pollination-dependent cropland. We found that when pollination-dependent crops (commercial-scale or residential-scale) are nearby, 30–50% of the garden bee community could potentially provide pollination services to adjacent crops.
But, we currently know so little about bee movements in complex landscapes ~ if and how bees move across roads or through gardens embedded in housing developments. This question will be a focus of our future work.
Some of the bees collected from our 2017 Garden Pollinators study.
Over the past year, I have have given many presentations that highlighted the high bee activity at ‘site 51’; a garden that is fairly small (0.1 acre) and in a heavily developed area of East Portland. Despite its size and location, ‘site 51’ had the second highest number of bees from our 2017 collections. I suspect bee diversity will also be high at site 51.
This garden is managed by someone who is an avid Xerces Society member. He gardens specifically for pollinators, and it shows! His garden is a true testament to the idea that ‘if you plant it, they will come’.
So what plants are in this garden? Our preliminary plant list (from a brief 2017 survey) can be found below. I will add Latin names, when I have a moment. For now, I hope that the common name list might introduce you to a new plant or two that might work well in your own garden.
Several of the plants in this garden are native to the Willamette Valley, and are included in Aaron Anderson’s study of native plants. The photos in this post are from Aaron’s field research.
Gail’s manuscript on bees in home and community gardens has been published in Acta Hort. Briefly, the results of this literature review are that: 213 species of bee have been collected from a garden habitat; gardens have fewer spring-flying and fewer ground-nesting bees, compared to non-garden sites; I suspect that over-mulching might be cutting out habitat for ground-nesting bees in gardens.
Aaron presented his first Extension talk to the Marion County Master Gardeners. This 90-minute talk was an overview of using native plants in home gardens.
The entire lab is getting ready to present their research results at the 2018 Urban Ecology Research Consortium annual conference, to be held in Portland on February 5th. A few highlights of our presentations, can be found below.
Gail’s Poster on Urban Bees: we sampled bees from 24 gardens in the Portland Metro area (co-authored with Isabella and Lucas)
Most of the bees that we collected await identification. We did find a moderate relationship between lot size and bee abundance: larger yards hosted more bees. But, we also found evidence that suggests that intentional design can influence bee abundance: one of our smallest gardens (site 56 = 0.1 acre), located in the Portland urban core (surrounded by lots of urban development) had the second largest number of bees (42), of the 24 gardens sampled. This garden was focused, first and foremost, on gardening for pollinators. The plant list for this garden (photos, below) includes: borage, big-leaf maple, anise hyssop, globe thistle, California poppy, nodding onion, yarrow, fescue, goldenrod, Phacelia, Douglas aster, lupine, mallow, columbine, meadow foam, yellow-eyed grass, blue-eyed grass, coreopsis, snowberry, Oregon grape, trillium, mock orange, pearly-everlasting, serviceberry, coneflower, blue elderberry, currant, milkweed, dogwood, shore pine, crabapple, cinquefoil.
Mykl’s Poster on Urban Soils: we sampled soils from 33 vegetable beds across Corvallis and in Portland (co-authored with Gail)
All gardens were tended by OSU Extension Master Gardeners.
Gardens were over-enriched in several soil nutrients. For example, the recommended range for Phosphorus (ppm in soil) is 20-100 ppm. Garden soils averaged 227 ppm. The recommended range for Calcium is 1,000-2,000 ppm, but the mean value for sampled beds was 4,344 ppm.
In the first year of establishment, of the 27 flowering plants that were the focus of this study, seven natives (lotus, milkweed, camas, strawberry, iris, sedum, blue-eyed grass) one non-native (Lavender) did not bloom, or else did not establish
Several natives attracted more bees than even the most attractive non-native (Nepeta cataria, or catmint). These include:
All bees have been pinned, labelled, and data-based. Now we’re (and when I say ‘we’re’, I’m mostly referring to Lucas and Isabella) are going through the painstaking process of photographing all specimens: head on, from the top, and from each side. We’ll then start sorting them by morphotype (how they look), and working to identify them. Some of the bees are very common, and fairly easy to identify (like Anthidum manicatum, Bombus vosnesenskii, Apis meliifera). Others will take a bit more time and expertise to get to species.
You can take a look at the entire album, representing about 150 of the nearly 700 collected bees. We’ll be adding the rest of the bees, as we can.
We collect and pin the bees, because most are difficult to identify, without getting them under a microscope, and without the help of a museum-level bee specialist. For those bees that are easy to identify by site (such as the ones listed above), we only collect one per garden (so that we have a record of its presence). We don’t collect multiple specimens of the same species, if we can identify it in the field. And, we don’t collect obvious queens (larger, reproductive bees).
We collect using a combination of water pan traps and hand collection. For hand collection, we use a pooter (an insect aspirator) for the smaller bees and baby food jars for the larger bees.
Water pan traps. We buy plastic bowls from the dollar store, prime them, and paint them with UV paint that is optimized for the wavelengths that bees see.
Here, I’m holding an insect aspirator, otherwise known as a pooter. You can suck insects off of flower heads without damaging blossoms, by carefully placing the metal part of the pooter, over the bee. It is then sucked into a small plastic vial, which I’m holding in my right hand.
This is such an exciting part of the research for me. I find myself obsessing over the photos, trying to organize them in my mind, and to at least get them to genus. Grouping them by genus makes it easier for an expert to sort through and identify them. And, I’m so grateful for their assistance, that I want to make it as easy as possible for them!
We’ve collected bees from gardens near Forest Park, in Portland’s city center, and in outlying suburbs. We’ll analyze the data to see if there are any patterns associated with garden location (forest, city, suburbs), or to see if there are specific bees that are only found in forest gardens, for example.
Listen to the episode, where we talk about the importance of gardens to native bees, our current research, and some key questions that remain to be answered regarding gardening for bees.
#OverlyHonestMethods is a hashtag that is trending on Twitter. With this hashtag (which is simply an easy way to sort and find posts), scientists share the honest, ugly truth behind research. Some examples:
“Data was not recorded on Sundays because I didn’t feel like coming in, and not recorded on this day because spiders” #OverlyHonestMethods
“Got a random number by asking my mom for a 3 digit number b/c I was too lazy to use an actual random number generator” #overlyhonestmethods
“Only read the abstract of the paper cited because I don’t have any money to pay for the full paper.” #overlyhonestmethods
This past week, I felt like I was swimming in my own #OverlyHonestMethods research sorrow.
For starters, my particular project in the Garden Ecology Lab is to document pollinator biodiversity within 24 Portland-area gardens. I LOVE this project. It’s the project I’ve wanted to do since I arrived at OSU, in 2007. But, there are two minor issues with this project.
Distribution of 24 gardens, being sampled for insect pollinators, 2017-2019.
Blue, yellow, and white pan traps ~ placed into home gardens to passively sample insect pollinators.
One of our beautiful, Portland-area garden study sites.
First, it takes me 6.5 hours to drive to all sites, in one day. This is without doing any of the actual research. I had originally planned to sample all gardens June 21-23 ~ but this plan was quickly scrapped when I realized that there would be no way that we could physically drive to all gardens, set traps, sample for 10 minutes, and then return to pick up all traps the next day.
Working dawn to dusk, we were only able to sample 13 of our 24 gardens, June 21-22. So, we pushed our second set of garden samples (the remaining 11 gardens) to June 29-30. Not ideal ~ but this is why we are replicating our study across three years, and will be sampling gardens once a month, for 3-5 months, within each year.
In less than one week, I’ll be welcoming nearly 1,300 Master Gardeners to Portland ~ for a conference that begins on July 9th (pre-tours), and ends on July 17th (post-tours). That means that my crew and I have been stuffing 1,300 envelopes and bags. We’ve printed and are putting 3,900 meal tickets into 1,300 badges. I can’t over-emphasize how much work this conference has been (and continues to be!). On the one hand, sampling pollinators just before this conference is the LAST thing I needed to do. On the other hand . . . after spending too many late nights in a hot room, filled with boxes and boxes of conference envelopes, sampling garden pollinators is exactly what I needed.
Of course, when it rains, it pours. Last week, we also had issues with our Native Plant study. On Tuesday, I get a call from Aaron, who tells me that: (1) someone trespassed onto our plots, and sprayed herbicide, and (2) someone pulled our plants up, by the roots, in one of our study blocks (replicates).
Native plant plot. This poor plant was ripped out of the ground, and/or had herbicide applied in the vicinity.
Native plant plot. This one was spared the wrath of wreckless weeders and herbicide applicators.
It’s a long (and enraging) story. But, long story short ~ we lost all of the plants in our fifth study block. We only have five blocks / replicates in this study (with 24 plant species ~ it is both expensive and expansive to include more blocks). So, in one sad, sad day ~ we lost 20% of our replication, which will have negative impacts on our statistical power.
How will we cope? We’ll regroup and replant. We were already planning on repeating this study in 2018. Now, it seems like we’ll have to repeat in 2018 AND 2019 ~ which is a bummer . . . because this will extend Aaron’s time in grad school, will cost me 50% more to get him through grad school, and generally makes a sad, sad day for all.
But, the silver linings are: I love working with Aaron, and don’t mind supporting him for an extra year, and Aaron had already mentioned that he might want to stay on for a Ph.D., which would necessarily lengthen and/or expand the scope of his study.
C’est la research. Perhaps in 2-3 years, we’ll all be able to have a good chuckle about this challenging month.
