BIOLOGIST ROBERT GEGEAR wants our help. He wants us to become Beecologists, as in, citizen scientists who help with the study of the ecology of bees. Our native bumblebees, specifically. He wants us to get to know them by taking photos, and contribute to scientific research by sharing those sightings, and in the process, learn to make gardens and landscapes that support them.
Robert Gegear is an assistant professor of biology at University of Massachusetts-Dartmouth, whose research interests include the conservation of native pollination systems, floral evolution, and bumblebee ecology. He’s one of the founders of the Beecology citizen science project, with Worcester Polytechnic Institute, funded with a grant from the National Science Foundation. Begun in Massachusetts, it is now getting data from citizen contributors over a wider area, and welcomes photos of bumblebees on flowers from throughout North America.
In our chat, I was surprised to learn that a bumblebee species may prefer a different plant for nectar than it does as a source of pollen, and also what role pollen serves for the bees (not just for the plants they pollinate). And that though there are a lot of lists out there of “bee plants,” many of them aren’t based on research—but rather on less-formal observations of bees being seen on certain flowers. It’s time for that to change, and each of us can help.
Read along as you listen to the August 5, 2019 edition of my public-radio show and podcast using the player below. You can subscribe to all future editions on iTunes or Spotify or Stitcher (and browse my archive of podcasts here).
the ecology of bumblebees, with beecology’s robert gegear
Margaret Roach: Welcome, Rob. I thought we could start with a brief description of what is Beecology, the project Beecology—its goals, and how did it start, and so forth?
Robert Gegear: To give you a bit of history on the project, as you know, pollinators have been declining worldwide for over a decade now, and we still don’t know the cause of these declines. But things like pesticides, disease, climate change, invasive species, and habitat loss are all thought to be contributing factors. Some of these… so, my lab is studying all these things. And in some cases, like with some of the pesticides and disease, you can do experiments in the lab. For the others, like habitat loss and climate change, and invasive species, you need to go out and do field work.
Rob: So I started to do field work looking into some of these causes, and found some really interesting findings, looking more at the species ecology. And it was just myself and one grad student, and I needed to scale up the project. And so I thought, there’s no better way to expand out than to include citizen scientists in the project, and so I created the Beecology Project, which is my way to rapidly collect data from a large area. And these data are on the ecological preferences of different threatened pollinator species, and also trying to get information on plants and pollinator interaction.
Margaret: Right. And so there’s a browser-based app that people can use, and we can talk about that little later, and that’s how they share, that’s how they become citizen scientists who share their data with you.
Now, you have a particular interest, you know, we hear about a lot of headlines the last couple of years, especially about honeybees. Colony collapse disorder, and this and that. And I’m interested in that, but you’re really focusing on bumblebees, our native bees in the genus Bombus, yes? And so it’s a little bit different from the honeybee thing.
Rob: Yes, the pollinator decline issue, really the issue, there are two contexts that we’re seeing declines in one case with the honeybees in an agricultural context, and crop pollination. And the other is more an ecological context, so understanding the relationships between the pollinators and the plants, and how they relate to the rest of the ecosystem, and biodiversity. And bumblebees are important pollinators in these systems, and help to keep ecosystems going, along with the thousands of other bee species native to North America, as well as butterflies, flies, and beetles, are all important pollinators as well in this ecological context.
So we’re starting with the bumblebee, and I’m focused on the bumblebee, and I’ve been studying it for over 20 years, but really the techniques we’re developing and some of the information that we’re gathering can be applied to all types of pollinators, not just bumblebees.
The bumblebees are easily accessible, are easily identifiable by citizen scientists, which is why we’re starting with the bumblebees.
Margaret: O.K. And when you say the bumblebees, there are… I’ve read in different places in the United States that there are 46 species, or 49. I don’t know how many, but who, what’s the number?
Rob: [Laughter.] The number that I give is “approximately 50,” so there were some parasitic bumblebees that were in a different genus, that were changed from Psithyrus to Bombus, and now are included in that bumblebee number, so the number went up when those species were included. There are roughly, so roughly 50—25 east, 25 west—and as you go farther north, you start to get new species… or diversity increases generally as you start to move farther north, and to higher elevation.
Margaret: So you said that you were just talking about the importance of honeybees, especially in the agricultural setting as pollinators. I sort of think of them as like a farm animal, in a way, do you know what I mean? We’ve put them, humans have put them into service to do this work, and in fact we imported them when we came to settle this country since they’re not native to here. But the bumblebees, as native bees, are I think what’s called a keystone species. Can you explain that?
Rob: Yes, so again, in the ecological context, what our native pollinators do, including bumblebees and the other things that I mentioned, it’s not just… What I want to point out before I go into the keystone species idea, because it’s not just the animals. We talk about pollinator decline, and it’s really focused on the animal, so we’re concerned with saving the bees. But really, what’s important here, the term “pollinator” itself is a plant-based term, and an animal can only be called a pollinator if it’s performing a particular service to the plant, helping it to reproduce.
Rob: If not, it’s just a flower visitor. And so really, what is important is the interaction between the native animal and the native plant that it goes along with. So there are special interactions, so the plants have evolved to target certain animals, and the animals have evolved to target certain plants. And together, they form what’s called a pollination system.
And so, the diversity of these systems that we have form the foundation of the ecosystem. So you can think of a pollination event as providing food for wildlife, so animals that as the plant is pollinated could eat the fruit produced. Birds and small mammals will use that as a source of food, or birds will use the plant material as a nesting site, or shelter from predators.
Then that what’s called trophic level then feeds the next trophic level up. So the hawks are eating the birds, and eating the small mammals, and so that interaction between the pollinators and the plants are keeping all of that going. And as we start to remove the diversity of those interactions, we’re going to start to have an impact on the birds and the small mammals. And I think that in the declines we’re already seeing some of that breaking down, and eventually what’s going to happen is we’re going to get what’s called ecosystem collapse, where we get this massive reduction in biodiversity.
And the problem is, we don’t know where we are in the process, so we’re trying to figure out what’s going on with pollinator decline, how it’s impacting not just native plants, but the wildlife that are connected to those native plants.
And that’s really what the goal of the Beecology Project is: to understand the ecology of species, pollinator species. We don’t have a good understanding of things like nest sites, and food preferences, and overwintering sites for most of the species, especially the bumblebees. And unless we understand this, we’re not going to be able to fix things, and prevent this reduction in biodiversity.
Margaret: So they’re a keystone species because they are integral, critical, in that system, that network that you just talked about. And they’ve co-evolved with all these plants, and so many other species in the system, one dependent on the other. If one goes, the dominoes fall. I mean is that why they’re a keystone species?
Rob: That’s exactly right. Yes, so it’s like the ecosystem rests on the shoulders of our pollinators. The terrestrial ecosystem, anyway. Aquatic’s a different story.
Margaret: Right. So a couple of years ago, a field guide to bumblebees of North America came out, and I interviewed one of the co-authors. But one thing that I remember, or I recall, was that he described bumblebees as… because I’m a gardener I guess… he said, “Well they’re annuals, Margaret.” Can you explain the bumblebee’s basic life cycle?
Rob: Yes, so that’s in comparison… that statement is in comparison to managed bees, so honeybees. We give them a place to live, we feed them, we treat them for disease, we help them to mate, and there are a couple of bumblebees… There’s one bumblebee species in North America that’s also managed, that’s used to pollinate crops. And there are a couple of other solitary, native bees that are used to do the same thing. But the honeybee hives persist through the seasons, year to year.
So bumblebees have an annual cycle. The queens overwinter, so they can be chilled close to freezing, and in the spring they emerge from their overwintering site and they start searching for a place, a nest site. Once they find a nest site, they start collecting pollen. They form a pollen ball, lay eggs in the pollen, the eggs hatch, the larvae start to eat the pollen, and the queen will feed the larvae, and then the first brood of workers will emerge.
Those workers continue to forage for the colony—the queen stays in the colony from that point forward. The number of workers increases through the summer, and then at the end of the cycle, they switch from producing worker bees to male and queen bees that mate, and then the queen finds a place to overwinter, and everybody else dies the first or second hard frost. And then the cycle continues.
So it’s annual, in that everybody is… the queen survives the winter, but is the only one, and then the cycle continues.
Margaret: Right, and she’s… I don’t know if we would call it gravid, or she’s a mated queen, so that’s why she’s able to carry on, because that mating took place before she overwintered, yes?
Rob: That’s correct, yes.
Margaret: Yes. So you talked a little in there, you mentioned pollen and nectar, and different things, and I once heard a Harvard researcher call bumblebees “aerial tankers”, for their sort of back and forth gathering of loads of nectar and pollen. What are these different cargoes… so these cargoes they have, the bees use them for different things in different parts of their life cycle. I loved on the Beecology website, you had this phrase, it said, “Nectar equals fuel. Pollen equals new bees,” which you just kind of described, yes?
Rob: Yes. So bumblebees can survive quite a while on just nectar alone, so in the lab we can give them sugar water and they’re perfectly happy for a month. But if we don’t give them pollen, they can’t make new bees.
Margaret: Yes, I didn’t really understand that.
Rob: And so pollen is… and that’s true across bees, that pollen is a critical resource, and what our research is showing is that bumblebees, at the species level, prefer some plants for nectar, and some plants for pollen. [Above, some pollen favorites; below, some nectar favorites from the Beecology site.]
Rob: Very rarely are they using the same plant for both things. So there are some plants that they’re extremely active collecting pollen, St. John’s Wort is an example, meadowsweet at this time of the year in this area is another example. And then they’ll use completely different plants for nectar. And the worker bees use different plants than the male bees. And even though they’re both around at the same time, so there is some overlap between workers and males, we see males on one plant species, and we see the workers on another plant species. And we’re trying to figure out what’s driving those preferences. But I think one of the biggest findings was this difference in the nectar and pollen.
It turns out that bees are actually, bumblebees are really pollen specialists. If we see bees on 25, 30 different plant species, they’re only collecting pollen from one or two of them. And the nectar that they get matches up to their tongue length, so some bumblebees have long tongues, some medium, some short, and if you’re planting a garden, or restoring a habitat, you have to make sure you meet the needs of the short-, medium-, and long-tongued bees. The long-tongued bees are the ones that are in trouble, and so you have to make sure that you give them tubular flowers for nectar, but then you have to also have these nectar sources that they prefer.
Margaret: So, and this was what I loved about searching around on the Beecology website, and obviously I’ll give all the links so that people can have a look, is that you showed graphics, photos, of bees and flowers. And you grouped them by short-tongued specialists can use these, medium-tongued specialists can use these, long-… You know, and it was so clear suddenly, it just illuminated it for me in a way that just talking about it, or reading about it, doesn’t.
I could start even as a layperson to draw some inferences, and make observations. So that was kind of wonderful, and you also say on the site, “Unfortunately, we do not know what most species need, but as a Beecologist you will help us to figure it out.” So that’s the call to action, where we can jump in, right?
Rob: That’s correct. That the problem is, there are a lot of plant lists out there for bumblebees and other bees, but those plant lists aren’t based on research. More, you see bumblebees on particular plant species, and then you put it on the list. What’s interesting is that all the bees that are… So first of all, pollinator decline, all pollinators are not in decline. That’s a misconception. Some are in decline, and others are doing better than they have done historically, and that gives people a false sense of security. They see a lot of bees, and they think, “Oh, this is great, this plant’s great, look at all the bees.” And it turns out it’s all one species, and that species is the common species, and at this time of the year in Eastern North America, it’s Bombus impatiens.
So all of the species in decline are from the same functional group, they all have long tongues, or they have short tongues, but they have an innate behavior, they’re nectar robbers, which means they prefer tubular flowers for nectar, and they bite a hole at the base of the tube, and rob the nectar from the flower without going in and pollinating the flower like the long-tongued bees do. But that system has evolved. And so within that functional group, those are all of the bees that are in decline. The other bees, bumblebee species with short and medium tongues, are not in trouble. They’re common, and they’re doing… they’re stable, or they’re doing very well.
And so we need to separate out the bees based on functional group, and not diversity, and not abundance. The abundance is important in an agricultural context, because the more bees you have, the more chance you have of pollinating all your crops with a single type of flower, single species, if you call it that.
In the wild, however, we’ve got hundreds of plant species that need pollinating and they fit… they’ve evolved to attract these one bee, be pollinated by these long-tongued bees. So we have to form those matches in order to help those species, and help that system, and thereby helping the wildlife that depends on that functional diversity of pollinators.
Margaret: So all that sort of circles back to the app that you’ve created, the Beecology website and so forth. So let’s go through what you’d like me to do if I’m a citizen scientist. And where are people to do this? You started just in Massachusetts, yes? And I don’t know if people are contributing data from other places now, or what?
Rob: They are, actually, yes. So the project is growing. We had, I think, 1,500 entries last year, and we’re going to be past that this year. It started in Massachusetts, and is expanding out to other New England states, so we’re in Rhode Island, and New Hampshire. But I’m getting some submissions from New Jersey, and I’m happy to take data from any part of North America.
And so the way that you can contribute to the project is if you go to the website, we have developed what’s called a web app for Android and iPhone users, and you can use that.
So what you can do is you take a video of a bee, a bumblebee/plant interaction, and then you upload the video to the app, and you can go frame by frame and slow down the video to get a good angle to take a still frame of the bee/plant interaction. And there are videos on the website to help you in this process, and I give workshops in the area to help people to use the app.
The app then walks you through the ID process for the bumblebee, to get the species, and whether it’s a male or a worker. And then equally important is entering the plant data. What is the plant species, and also the behavior. Was the bee collecting nectar and pollen? We have videos on the website, showing you what a bee looks like when it’s collecting nectar, or collecting pollen.
And then that gets sent to our database, where it’s combined with all the other data, some of museum specimens, some of research data from my lab, and you can go and look at these, using these visualization tools, to look at diversity. You can look at the plant/bee species level interactions, and we’ve got some new tools that we’re going to deploy in the next month or so as well, some data-analysis tools.
Margaret: And so what seems to be difficult, if I were to just be outside in my garden, and I’m looking around, and I’m saying, “Oh, there’s a bumblebee, but I don’t know which species,” with this, the guidance that this app provides, it helps you narrow it down as you just said, and it’s so logical. It’s like, O.K., question Number 1, is it more black, or more yellow on it, and where is the black and yellow—and do you know what I mean? Because you know the body patterns, you have that all coded into this thing, it helps you narrow who it is, yes? [Above, image of markings of local bees from Beecology site.]
Margaret: And then, right, and even guides you, I think toward some floral IDs, doesn’t it help with that as well?
Rob: Yes it does, and that’s a new feature. We’ve got students working on that right now, where it’s going to link to our website, where you’re going to be able to look at the flower and match it up, and go through an ID process to ID the flower. And everything that goes into the database, I’m the overseer, so I can change if they make a mistake on either the bee or the plant side, I can change things.
Margaret: Right, right.
Rob: And you can retrieve your logs and see if I’ve changed things, to help that process as well. But yes, it guides you through the ID both of the bee and the plant.
Margaret: I wanted to talk about some of the things you’ve learned so far, and maybe some of the things you’re hoping to learn, because so little, relatively, I guess, is known yet. I mean just the fact that all this time, when I saw… is it called scopa, is that what the parts of, almost on the back legs, where the bees sometimes get the pollen collected? Is that right?
Rob: The pollen basket. [Clarification: Technically, the term “pollen basket’ only refers to the corbicula, which is present in bumblebees and honeybees, while Margaret’s wrong guess of “scopa” are pollen-collecting structures present in other bee groups but not bumblebees. Scopa are not referred to as a pollen basket, although the pollen on the bee may look the same and be in the same location in some cases. This page from Xerces Society has an explanation and a photo of a bumblebee’s pollen basket, under “Foraging”.]
Margaret: So all this time I’ve thought the bees were just in service to the plant, to move pollen around, and cross-pollinate and all that. But I didn’t know the part about that new bees, and that they’re dependent on it to procreate and so forth, to successfully raise new bees. Have there been some “ahas,” already, and kind of what’s the grail? What are you looking for?
Rob: When I started the project… so I’m originally not from Massachusetts. And so I had to learn the bumblebee species and figure out what’s here, and what’s not here. And someone from the state told me that there was one species that was no longer present in the state. And I thought that’s too bad, and interesting, but I asked where they had looked for the species. And I looked in Massachusetts, and as I said, I’ve been studying bumblebees for a while, so I have an idea where to find certain species.
And so I was giving a talk, and this was the first Beecology talk, or first or second Beecology talk, I said, “I’m looking for this bee, it should be in this area, it’s at higher elevations,” and at the end of the talk, someone showed me a picture of the bee.
Rob: So since that, many people have shown me pictures and submitted pictures of this bee, and I now have a range map for the species that I was told was no longer in the state. It’s alive and well in the state, and I am currently studying it, to try to figure out what its ecological needs are, where does it like to nest, what does it like for nectar and pollen source, where does it overwinter, so that I can figure out why it’s no longer in certain areas where it was historically, and hope to bring, expand the population back into those areas.
So people sending in… There’s another species that’s rapidly declining, and I was just earlier today was meeting with a Beecologist, and saw the species in their garden, and they were telling me what they’ve seen it on, and they’re going to do some observation for me to figure out what the ecological needs of that species.
And so that’s been the biggest… First of all finding the species was extremely exciting, and I think that I’ve located a Bombus affinis [the rusty-patched bumblebee], which is the first bumblebee on the Endangered Species List. So stay tuned for that, but that’s the biggest thing is that they’ve shown me where these populations are, and also given me the data on what are they doing, what are they eating?
Margaret: Well, Beecology, and hopefully we’ll send you some new Beecologists to contribute from the airing of the show. So thank you so much, Robert Gegear, for taking time to talk about Beecology.
Rob: Oh, thank you very much for having me on the program.
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