223 - Youngsteadt - Urban bees: what drives diversity and how do we measure it? (in English)

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Andony Melathopoulos: [00:00:00] As we've heard in previous episodes, the bees that we find in urban landscapes are of intense interest, not only to researchers, but to gardeners, landscapers, people who maintain parks. And the one thing that has become clear is that. It's a very complicated system. There's a lot of things that are underlying or driving the diversity, the patterns of diversity that we see in urban areas.

And that's why I was so excited to finally welcome to the show. Dr. Elsa young Ted. She is an assistant professor. And extension urban ecology specialist at the university of North Carolina, I've been long admiring her program, which is really doing topnotch extension, but really great and nuanced research on bees and urban areas.

So in this episode, we're gonna hear about some of those factors that go into potentially driving. Diversity and some of the UNC we ha certainty we have around those drivers. And then the [00:01:00] second part of the episode, we're gonna tackle the most controversial of all topics, how to measure B diversity specifically something that's come under a lot of scrutiny recently, these B bowls, how effective and biased are BBOs at predicting native B communities.

So we're gonna get into a lot of cans of worms in this episode this week. With Dr. Elsa young Ted on poll.[00:02:00]

Welcome Dr. Youngsta to pollination.

Elsa Youngsteadt: Thank you. Thanks for having me.

Andony Melathopoulos: Now we've had guests who have talked about the remarkable B biodiversity in cities. And I wondered if this also applied to North Carolina, are the bees in the cities, the same ones in agricultural settings or in natural plant communities.

Tell us a little bit about it. .

Elsa Youngsteadt: Yeah. And I actually often wonder the same thing. Does this apply because when you ask yourself what does it mean to have remarkable B diversity, that suggests there's more than you expected, but then what were your expectations? And so I often see. Studies of urban bees that conclude like, wow, this is more diversity than we thought would be here, but we never really know how much we expected to find.

So I actually find that kind of a difficult question to answer in just to put some numbers on it. Like in, most of my work is in Raleigh, North Carolina. Some colleagues have also worked in Durham, so we're in this like Piedmont area of central North Carolina. That's overall a [00:03:00] pretty disturbed developed area.

But between Raleigh and Durham, we've got a total cumulative species list of maybe 130 or so in these kind of urban and per urban habitats. And that's out of, five we're also working on a state checklist for all of the species ever recorded in the state of North Carolina. That's up to about 560.

I don't know is 130 out of 560 remarkable or not. It certainly seems like pretty good. Like we've got a good chunk of the diversity in these urban areas, but there's definitely species that I never see in urban areas that I do see in some more. Like more specialized or pristine habitats, like nice frequently burned Sandhill habitat.

There are some species that turn up there that I will just, I don't think I would ever see in a city. And certainly the composition changes like the bees that you see, there are some urban winners like specialists on violets. You will find far more of them here in this city than you do, even in a beautiful forest full of spring ephemerals in the spring.

So it's a mixed bag. There seem [00:04:00] to be winners and losers. But there's no doubt that cities are definitely supporting some solid chunk of B diversity.

Andony Melathopoulos: I love your nuanced answer because it is a hard, it is actually a really hard question to answer. And it's like, what subset of the whole fauna should we have?

It's unclear, before disturbance. And so you are left with this. And I love the example of the violet. I was thinking, so many people in urban areas, plant sunflowers that, the sunflower specialists may be like, punching up above what you might find in. Natural plant community.

So it is a very kind of nuanced question to ask. I always start with the nuanced once wait, what? Sorry. I always start with the trick it, oh, no, it's fine. I tr I start with the trick question. So let, but let's get even trickier because you've got, as you pointed out in this urban and very urban area, you have a, a certain amount of diversity.

and I suppose that area is not equal. So you would [00:05:00] have a park, there'd be an industrial area. You have wealthy parts that where people have a lot of resources that can be brought to bear on gardens and less affluent parts where the landscaping is minimal. So how do the patterns within the urban Imperial urban area influence the patterns of bees that we see?

Elsa Youngsteadt: Yeah. And you just hit on a couple. Big important and different drivers, like from the B perspective, flowers are the big obvious driver of B abundance and city like cities. You go to a botanical garden or places with intentional pollinator gardens. You're gonna find more bees than if you go and try and sample on a monoculture turf lawn.

And the way flowers are distributed in the city is. Driven, partly like you mentioned, probably by socioeconomic factors by wealth and the ability to invest in ornamental landscaping. And I don't have the bottom line on the wealth and B diversity. Question yet. I know there are a lot of projects [00:06:00] ongoing.

Like I just I've heard informally from other students and other labs who have ongoing work in that area. My lab is one of those. So I'll mention a PhD student in my lab, Kate Gorman. Who's got an ongoing project trying to unpack whether this so called luxury effect exists in bees. And if so, Kind of what's driving it because you could actually imagine it going two different ways.

Like I mentioned, flowers are one of the big drivers of be populations, but then they don't just have to eat. They also have to nest somewhere and nesting resources could also be limiting populations. We know the majority of our bees are nesting in the ground. Ground nesting resources are slippery.

They're it's hard to know exactly what any given species is looking for. You can't just go out and survey and be like, oh yep. This is good ground nesting habitat. The way you can say this is good flowers. And you can also imagine that, but we do think in general that like access to bear soil is a basic prerequisite for ground nesting bees for most species.

And you can imagine that access to bear soil also [00:07:00] could vary across socioeconomic gradients, across investment in landscaping. So you might have a lot of flowers and wealthy areas, but you might also not have a lot of bear soil if you're also seeing a lot of investment in your irrigation and turf. So those resources could potentially get decoupled.

So Kate's doing this project across residential yards in Raleigh, across across the range of sort of median income groups in our census blocks to try and get at how those both aspects of, both kinds of B resources may be shifting across socioeconomic gradients. And then what the actual upshot is, where for B diversity, maybe it peaks somewhere in the middle.

That's yeah. Great question. I hope we'll have some better answers soon.

Andony Melathopoulos: That is a fascinating the way that you frame the problem is fascinating to me. And I guess as Kate's work comes to fruition, you may see, I'm sure even gradients of. Affluence can be really sharp and they can be subtle.

And so you do have those effects and [00:08:00] I did wonder, I wanted to pick up, you've mentioned in your answer that I thought it was a G. Fascinating point that, we often focus on floral resources and we have ways of measuring that number of bees, diversity of bees visiting, but that there's this real problem.

Being able to assess the quality of nesting resources. How is Kate trying to tackle that problem?

Elsa Youngsteadt: Yeah, she's been through a couple of iterations, like the first field season. She went out. And under my perhaps misguided influence, we just randomly placed emergence tents on different ground covers in these yards on turf and on bear dirt and on mulch because we really.

We always hear the conventional wisdom. That's gotta have bare ground, but is that really? Because that's the only place they're nesting or because that's the only place you see them nesting. And so you think that's where they are, because they're just started to detect. So we were gonna try and, use random placement of traps to get through those assumptions and see if [00:09:00] they're right.

But she caught, I think two BS all summer in those emergence tents, which. And maybe I should define what an emergence tent even is. They're starting to get used more often and be research with mixed results, similar to ours. But it's basically a little tent. Ours are, I think, 60 centimeters on a side that you pin down over the ground, and then there's a collecting head at the top.

So any B that. Is in a nest in the ground at the time you put the tent down if it emerges either because it's, a brand new bee starting its life cycle above the ground, or because it's a female who's coming in and out of that nest and was in the ground. When you put the trap down, they'll fly up into the collecting head in the top of this trap and get documented.

And it. A pretty common result for people. Who've tried to use these, that you don't get very many bees, but it would be a brute force effort to get a strong pattern using them. And we tried and it seemed like the brute force was gonna just be more than we could take. So what Kate's done the second [00:10:00] summer is just visual searches for nests in all of these habitat types on transects.

In her yards. And then when she finds a candidate nest, any little hole in the ground, she goes and puts a trap over it to see if it was really a B nest or something else, maybe a wasp or some ants, or, anything else that digs in the ground. Oh, that's a great idea. And that has hugely increased her success rate at actually detecting B nest.

A lot of what she finds really are B nest. And then of course, we Haven. We're still identifying them. We don't know yet if there's really, more nests in a particular part of our socioeconomic gradient or in particular parts of yards, but that has definitely stepped up our ability to document nests.

Andony Melathopoulos: We look forward to seeing the results. That is a great solution. And I have to admit, I have colleagues here at Oregon state university that have taken the same method of putting these tents up and really not getting a lot of data from them. So this is a really great solution of combining the two together.[00:11:00]

Elsa Youngsteadt: Yeah, I still worry about the bias of like where you can actually see nest more easily. And another solution. And we can talk about this or not if you want. But another solution actually is one that Mike Eisha and his colleagues in Georgia came up with, which was to just rotate the location of the traps periodically.

And they greatly increased their B detections. That way, rather than just put 'em on one spot and leave them for the summer, if they shuffled them. I don't remember every week or so. They caught a lot more bees and we were gonna try that. But working in cities is weird. Like when you're working in somebody's yard they don't necessarily have, you can't just say, okay, I'm gonna come in here.

I'm gonna put this here this week. And then we put it here next week. There are restrictions. So we, we came up with our compromise.

Andony Melathopoulos: And I have to say, on that point, I know, there's a very nice mining bee, nesting bed by the Hoyt Arboretum in Portland, and it's all on turf and you can see them yeah.

That they just pop outta the ground. And then you, if you come back later, it would [00:12:00] just look like grass. So it is a little bit they're these biases are maybe unavoidable. It may be impossible to get anywhere without some bias, but yeah, nevertheless, Keeping that in the back of our mind is I seems like a but not being paralyzed by it.

yeah. Okay. This, that's a very exciting, and it's really exciting to see the nesting component come in and like making this picture much much more complex and just to raise the complexity. The other thing, I, when I think of cities is I think, there's variability, some places are completely exposed.

Maybe there's a new set of plantings for. Some small trees, but it's sunny and hot and everything turns brown and other places are these huge mature trees that cast a lot of shade. And I imagine with B shade is a kind of double edged sword. It kinda cools, and they may not want to go there, but at the same time it can [00:13:00] get pretty hot, especially these days.

Elsa Youngsteadt: Yeah. Yeah, that's a great observation. I agree with you that if you are gonna go out and look for bees, like in the shade is not where you typically look, they're not usually like a lot of plants that produce nectar and pollen also are not shade loving. So I'm not sure how much of it is like where the bees are comfortable versus how much of it's just where their resources are.

But. The presence of big trees, or maybe I should start on the other end. The absence of big trees from like developed downtown areas is one of the major contributors to the urban heat island effect like that. If there are no trees, it's gonna be hotter. And at least this is. Coming from my bias perspective of working in Eastern forest ecosystem.

So if you're talking about, desert or grassland cities, things might be different, but in a forested ecosystem, the absence of trees and cities is one of the things that makes them hotter than their surroundings. And we know from other studies we've done in Raleigh, that [00:14:00] some bees can take it hotter than others.

The ones that can't take it real hot, you don't find them in these in. In urban heat islands their populations tend to decline in the hottest parts of the city. So even though you're not gonna actively find bees foraging in shady areas anywhere, the fact is the shade is like cooling the air. And then that cooler air is still mixing with the air over your sunny pollinator garden.

And overall that habitat is not gonna be as hot as it would be. In a downtown where their trees are not making any cool any cool air anywhere. There is no cool air to mix with. And it's just getting hot as blazes.

Andony Melathopoulos: How does this cash out? Like how, what are, what's the balancing point and how important?

I imagine one component of trees is the nectar and pollen. They produce that. There's some great

Elsa Youngsteadt: NEC that's the other one that I didn't even acknowledge is the trees themselves can be huge resources, especially in the spring, like in. Biome over here in the Eastern us anyway, a lot, a huge amount of the nectar and pollen resources are coming from trees [00:15:00] themselves.

And even in forests in the early spring, before the leaves fill in the forest floor can be a great source of floral resources. And those tend to be also pretty, ephemeral vs who are just active for that little amount of time in the spring. And then you don't see them forging in the shade once the trees fill in But from an urban perspective, what's the upshot.

Like you gotta have some trees to cool things off, but you can't have too much shade. Or the rest of the floral resources that the bees need for the rest of the year after the trees stop blooming, aren't gonna grow in the shade. And there may be. It's hard to retrofit a downtown with big trees.

As you already noted, like if you put 'em in a miserably hot habitat, they don't tend to take off. There can be some nurturing that can definitely increase canopy cover in certain urban areas. And that's one strategy for reducing urban heat islands, as long as you're, also keeping.

Other floral resources around there are also other urban cooling strategies, things like, light colored rooftops, or other ways of reducing the heat island that can be effective. I think [00:16:00] the other thing I wanna comment on is that it doesn't just matter how hot it is. Like I said, some bees can take it hotter than others, but then that also is not the only thing that matters.

Like you can think of it almost like a pesticide risk assessment where you're interested in how sensitive a B is to an insecticide, but also how much is it, how much it is exposed to that insecticide. You can think of heat similarly, because you might have a B with a very low heat to. But who's very good at Thermo regulating or whose body never gets very hot or is only active at cool times of day to begin with.

Oh, and that bee might not be at great risk of overheating, even though it appears to have a very low heat tolerance. Whereas some bees with a very high heat tolerance might still be actually cutting it pretty close. Like we see that with bumblebees when we measure. Their heat tolerance in the lab.

It's medium. It's not the lowest of all the bees. But when we measure their body temperatures in the field, it's pretty high. They actually cut it pretty close. And so we might worry more about them [00:17:00] than some of the species who actually have a lower heat tolerance. Just because those other species aren't getting as hot in the first.

Even in the same habitat

Andony Melathopoulos: and you've evaluated this, you've taken different species and started to crack the nut of, how different. BT AA might respond to heat. Tell us a little bit about, you told us a little bit about bumblebees being surprising in that, they tolerate the heat, but they're not great heat dumpers per se.

What are some of the, yeah, actually have

Elsa Youngsteadt: some pretty remarkable. Themore regulatory mechanisms. There are elaborate things they can do to even though they've got this very hot flight engine in their thorax to shunt that heat off into their abdomen and avoid deadly temperatures, they still like still cut close.

And interestingly, one thing that we've found in my lab a student in my lab, Malia Nachi, who's moved on to do a master's now, but she was curious whether. Bumblebees carrying larger pollen loads actually get hotter, which sounds very intuitive. We carry, oh sure. Heavier things. We get sweatier.

But when Malia [00:18:00] wanted to start that project, I was like, oh, we're never gonna detect that in the field. That's a great question and you should try it, but don't hold your breath. She found a difference, like by going out and catching bumblebees with different pollen load sizes, really and controlling for their body weight and the environmental temperature around them.

They got about 0.07 degrees hotter per milligram of pollen. And they were carrying up to 30 ish milligrams of pollen. So overall, like about two degrees Celsius of their body temperature could be due to like how much work they were doing just by carrying resources back to the

Andony Melathopoulos: nest. This is fascinating because it isn't just I love how you've, how you think about this problem?

It's not merely. This thermal, temperature that they can tolerate, but it may also be that they compensate by lower loads. And so the colonies reproductive rate is impacted even though the B doesn't like croak.

Elsa Youngsteadt: exactly. I don't think for the most part, we're not gonna see bees like actively dropping out of the sky because they let themselves get too hot.

They've gotta do [00:19:00] something to avoid death. And that something is probably gonna have impacts elsewhere in their life cycle. If it means, bringing back less resource to the nest, cuz you've gotta carry a smaller load or cuz you just have to stop activity during a certain time of day. It's gotta add up somewhere in the life cycle.

Andony Melathopoulos: Fascinating. Let's take a quick break. I wanna come back. We have another topic that I want to pick up with you on the second half that. You've dangled in front of me and I think it's gonna be fascinating for the listener. So let's take a quick break and we'll be right back it. Welcome back.

So just switching gears, I guess it's not totally switching gears because we have, we, trying to estimate B communities in these different gradients, in urban areas where they're shade and. Requires some kind of sampling method. You have to be able to catch the bees. And many times in a lot of cases, you have to be able to look at them under a microscopes.

You need a specimen. But there is this question [00:20:00] of, the different. Meth methods and the biases, really predicting what's out there. And I know they're recently one of the most common methods that people have been using for years, we've used it for years as well are pan traps, these little colored traps with soapy water.

Why don't you describe the pan trap and tell us, why you became interested in the biases associated with. .

Elsa Youngsteadt: Yeah, so pan traps, they come in a variety of sizes and colors, but the ones that we use and that I think are most common are what probably even 10 centimeters diameter or so.

And they're little Sule cups that are. Painted with different colors. Usually a UV reflective blue, yellow, or white. And the general idea is that bees are attracted to be at least because of the color, but then you've filled them with soapy water. So the bees that come to check them out fall in and drown.

So it's a mean trick, but it's become a popular sampling method. It [00:21:00] seems to take out the question of observer bias. If you send a bunch of people out into a habitat with nets, different people might come back with different samples and you would get a different picture of the underlying B community.

And the idea with pan traps is that maybe it takes out some of that observer bias and gives you a more consistent yard stick of what is there. But then there's been growing debate over the past few years. Our pan traps really so unbiased. Like maybe they don't work well when there's a lot of flowers, maybe they overrepresent sweat bees.

And B biologists have noticed for a long time, but yes, if you go netting, versus if you put out pan traps, versus if you put out a vein trap, each method is gonna give you a different picture of the B community, but which one's actually right. Like we know each method is probably biased, but. There hasn't been much done to try and actually quantify those biases or correct for them to get a more, a clear view of what the underlying B community really is.

What is the relative abundance of the [00:22:00] different species? How common is any given species? Just because it's the most common in your bowls doesn't mean that it's the most common, in the

Andony Melathopoulos: habitat. So if people had hunches, but they never quantified well, was it just UN quantifiable? Is this some something that's beyond the questions of science?

It can't be validated.


Elsa Youngsteadt: I know it's not there. We tried to do a mark recapture study to get at some of this. In fact, we didn't just try, we actually did one. And so mark recapture is a method that's been. Common in wildlife biology for many decades and it's even used for some insects. But hasn't been brought to bear a lot on bees.

As part of our project, we did a lit review and found 20 different studies over the decades, tried to do population estimates, estimate like the abundance of bees in a habitat using mark recapture. So it's certainly not unheard of, but it seems to be a little bit neglected in the current debate of different biases because this gives you a method.

To actually quantify your, the [00:23:00] detectability of each B species or field identifiable B taxon in an environment. So you go out and you mark these for a day. You let them go again. Then you come back the next day, you see how many of that B is marked versus unmarked. And it gives you. An estimator then of what proportion of the population you're actually seeing

Andony Melathopoulos: on, let me get this straight.

So you, you mark the B you go out, you catch the B you say, ah, this is, this is best, the best taxonomic unit I can do visually. You write it down and you put a mark on it, and then you put your pan traps out and then you see am I seeing the same proportion? Marked bees in my trap.

Are I seeing a lot of them in my trap, or I'm not seeing any mark bees in my. Is that the idea?

Elsa Youngsteadt: Yeah. That's, that would be one way of doing it to actually get your mark recapture population estimate. You have to sample repeatedly. Non-lethal so we would go out three days in a row to try and Renet these that we had previously marked.

And so each [00:24:00] B got a day specific color. So we would have a capture history for a series of individual BS and that led. Estimate the population for each of those taxes. So that was one view of the community composition that should have been biased corrected for detectability because we did the mark recapture and then separately, the following week, once we had done those non-lethal estimates, then another team went out and put out the B bowls and also did timed netting.

And then we were able to look at the community composition in those samples and see which one best matched the bias, corrected estimates from mark

Andony Melathopoulos: recapture. Okay. So you've got the community structure, but you also have, you should get the same proportion of mark B's in the two different detection methods.

If they were reading the same thing, I'm not an oncologist. So I, this might be a little bit above my pay grade. Yeah, and

Elsa Youngsteadt: that we didn't get a lot of marked BS like the following week. And I think we might need to fiddle with the assumptions and the model if [00:25:00] we wait that long between capturing episodes, because we had two different teams in the field, there was the team doing the market capture, and then there was a separate team doing the pan trapping and Nett.

and there were different amounts of time in between sometimes just because of the weather. Oh, sure. So I think we would need to switch to an open population model that says that bees could die or immigrate during that intervening time, which over our three day boom, mark recapture episodes.

We were able to save. We were, we assumed that the population is pretty stable during that short time period that these are not getting added because they just disclosed or they're not disappearing. They departed or died. Okay. But everybody, listen, there would be a way to do what you're saying.

I don't even think about what that is

Andony Melathopoulos: exactly. Everybody's wondering though, how do you mark a, B

Elsa Youngsteadt: ah, yes, we just use a little paint pin. So we put 'em in a, B squeezer, kinda like a queen marking cage. Yeah. To restrain them and then just put a little paint dot on their back using a paint [00:26:00] pin.

Some be like a lot of bees seem to not mind that process at all. We've marked honey bees and let 'em go or, and leaf cutting bees. And they'll just keep go right back about their business. Not leave the area, just continue foraging as if nothing had happened.

Andony Melathopoulos: Okay. So what did you find?

Elsa Youngsteadt: So we found that the community captured in bowls was quite unlike the community we estimated using mark recapture.

So indeed supporting the idea that like, yes, the bowls are quite biased. They're not really giving you a good picture of the underlying B community that you would get. If you used a bias, corrected method, like mercury capture. We were interested to find though that the community captured by hand netting.

Correlated quite well with what we found using mark recapture. And that was especially interesting because different people were doing the netting on different days. It's not like the same person did mark recapture and then also went out and just did timed netting. These were different individuals.

And so of course, I'm not gonna say [00:27:00] that individual observer bias doesn't exist, but it was much less of a concern than we thought it was gonna. In this particular study,

Andony Melathopoulos: I imagine some of this must be great for people listening who are like, ah, but I really I can, I understand the terms of this debate, but I just I'm worried about observer bias, but I imagine when you tell it, I have, there are two, some of our best collectors, Dan and Michael they're brothers, and they collect completely, they're real clear about this is Dan sits and waits at a flower and really targets the smallest bee he can find.

And Michael is a kind of Grazer. He just is going around. But I imagine if you gave Dan and Michael, a very set protocol and said, this is what we want you to do, that would eliminate their kind of, their tastes for B collection. Yes, exactly. Fascinating. This is really great. I'm really looking forward to seeing this work as it develops.

Let's take one more quick break and we have a segment we do with all our guests for we wanna know if you have a book [00:28:00] recommendation, your go-to tool and most importantly, your favorite pollinator. So we'll be right back. Okay. We are back. I'm very curious. What I can see your bookshelf back there.

In fact, I'm curious if you have a book recommendation for our listeners.

Elsa Youngsteadt: The book that comes to mind is one, I'm sure that many of your guests have recommended, but the solitary bees and I should have looked up the correct order of authors before. Oh yeah. The book Danforth Minkley and. Ah, help ne Jack ne.

And is it that order stand

Andony Melathopoulos: ne they're gonna write us back. They're gonna you need to publish in Adam. anyways. Great book though.

Elsa Youngsteadt: Yes. I actually, I wrote a review for it once for American entomologists, which was a great incentive to actually read it from cover, to cover in a fairly like continuous sitting, which I'd completely recommend to anybody else who might wanna read it to it's a great reference book.

You can [00:29:00] open it up and, find whatever species or topic you wanna know about and read those details. But also it's a great read end to end. And you feel much more. Aware of the lifestyles and biology when you're finished, no matter how much, there's gonna be something in there that surprises or enlightens

Andony Melathopoulos: you.

We had an episode with Brian Danforth on the publication of the book and he, cuz I was curious how he would take so many disparate pieces of information. And synthesize them, all the authors synthesize them into what you describe a read. It's not a encyclopedia. It is like something that you can read.

And he had some, I can't remember what it was, but he had a, like a writing. Book that he read. I think it was his book recommendation and how

Elsa Youngsteadt: to write a lot. I remember, yes. that was it. I listened to that episode. but I have not read that book, which I actually started reading it and felt that whatever it was advising was something I could never accomplish.

So I stopped.

Andony Melathopoulos: It's a great recommendation and a wonderful book. And if [00:30:00] people don't have it yet, you really ought to pick it up. It's just don't be intimidated. It is Yeah, I was reading bees of the world recently, just like the, the introductory chapters and the print is really small for my old eyes.

It is. And I will say that solitary bees, good font size for


Elsa Youngsteadt: readable. and then I'm currently reading. I don't know if you can cut this out if you want, but no. I'm currently reading the mind of a B by a large Chica which I'm not very far into it yet. I'm still in the beginning sensory processing chapters, but I am.

Reading that one with great anticipation to learn more about just like their cognitive abilities and how bees learn and navigate. So I've never heard of this book. I'm not far enough long to recommend it yet, but it's, what's on the nightstand, but so

Andony Melathopoulos: far so good. Yeah. Oh, okay, great.

We will put those both in the show notes. And the second question we have is your go-to tool. And I do wonder if it's, it may not be the pan trap.

Elsa Youngsteadt: It is not, I think my go to [00:31:00] tool is the B squeezer. We use them for so many things. So if anybody hasn't seen or used one a queen marking cage may be more familiar, but maybe again, not to everybody.

So it's basically a tube or a vial. Like anything you could maybe your 50 mil tube that you could collect a B in, but it's open on both ends. So it's just a cylinder. And one of those ends is covered with mesh. So you've got an open end that the B can enter a mesh end that the B can be squeezed up to.

And then lastly, a sort of foam plunger that you use to press the B up against that mesh. So it holds it still, it restrains your B, but it doesn't squish. It doesn't hurt it. And then once your B is restrained, you can do, you can take its body temperature. You can paint it with a paint mark, you can glue a radio transmitter on it, any of these things.

So that would be my essential tool. So

Andony Melathopoulos: most of the, most of the research that you talked about, the B did you call it the B squeezer? Yeah. the B squeezer was [00:32:00] central there? Yes. Do you make your own B squeezer or is it just the queen marking cage?

Elsa Youngsteadt: We have some of each, we have some queen marking cages, and then we have our own that we've made out of bio equip, aspirator vials that we cut and end off of and put different size meshes over sponge PS, like for face painting, make pretty good plungers for the foam end so you can definitely make your own of different shapes and sizes and mesh mesh size.

Andony Melathopoulos: Oh, and listeners, we'd love to see your homemade B squeezers. Please send those images to me and I will share them. Widely last question for you is, do you ha I imagine it's very difficult and you work with so many pollinators in so many contexts. But do you have a favorite.

Elsa Youngsteadt: I do. And I'm always a little bit embarrassed that like my favorite be is one that's super common and drives everybody nuts.

But Eastern carpentry bees XPA virginica oh yeah. They're big. They have, they're big enough [00:33:00] that you feel like you can see they're character they're personality, right? Like the males are territorial they'll come hover in your. The females will also come hover in your face and look at you for it's less clear why they might be doing it.

They have fascinating life cycle. Like they over winter as adults, which is not unheard of, but a little bit weird. They made a little bit in the fall and then more in the spring. Oh,

Andony Melathopoulos: that, I didn't know. I thought they did it all in the spring cuz they're whipping around, but they do a little bit,

Elsa Youngsteadt: ah, they do sun in the fall.

You'll see mating flights, like starting. Yeah, probably around now. I haven't seen one yet this year. Okay. But in like September, October you don't get all of the big territorial guarding around the nests or around flowers, the way you do in the spring, but there's definitely some mating action. They have this really, the males have this very conspicuous sort of yellow or ivory colored spot on their face.

Nobody really knows what it's for. In several years ago, Charles Mitchner wrote a paper on how so many male bees have yellow faces and we don't know what they're for. Carpenter bees, big, glowing example of [00:34:00] that. Oh, that's interesting. They have this weird kind of, not exactly social, not exactly solitary behavior where females share nests, but it doesn't seem like the.

It seems like there's really one doing all of the work and then someone else just hanging out, waiting for the head, be to have a mishap so she can take over the nest. It doesn't seem like a true like worker queen set up. So they have all these interesting quirky things about them that we don't fully understand, even though they're like drilling holes in everybody's back deck.


Andony Melathopoulos: no, I imagine an extension as well. It must pre you, you must field. Dozens of calls every year. What do I do?

Elsa Youngsteadt: And we don't have fantastic answers. There, it seems like, if you read existing extension publications, the advice is, spray insecticide on the wood or in the tunnels but for people who wanna avoid using insecticides or who are worried about, non-target effects which I hope would be a lot of people there's not great. And they can ultimately, I, if you want, I can send you some pictures for the show notes, if that's a [00:35:00] thing, but like they can make a lot of wood disappear.

Like I've got x-rays of some benches here on campus showing like the amount of wood that is gone to tunnels. So I don't wanna just tell people, oh, don't worry about it. Like it, it could eventually do some damage. Yes. It would take many years, but like wood is definitely going away. We've actually currently got a survey.

We're just about to take it down and start analyzing the results. But we've been querying humans around the Southeast about their experiences with carpenter bees, how do you like them? Do you hate them? Why, what methods have you used to try and manage them? Have those methods worked? How expensive have they been?

Because it seems like, yeah, there's a ton of questions. The documented solutions are not very satisfying. And so we're trying to get a better documented picture of just what is going on out there. So that's better first steps toward doing something about it.

Andony Melathopoulos: Fantastic. And I have to admit we don't have Eastern carpenter be, we've got two species in the Southwest of Oregon and I'm always getting calls and I'm never, [00:36:00] I have that same.

I know, I didn't quite realize and maybe our species aren't quite as potentially destructive, but I don't know what to tell people. I say, I read the extension guides paint the wood and. But I don't. And as

Elsa Youngsteadt: soon as you say that, like 10 hands in the room go up but they're drilling in my painted XYZ.

That's clearly I've heard this

Andony Melathopoulos: too.

Elsa Youngsteadt: yeah, it's really not the solution.

Andony Melathopoulos: Fantastic. A great species. And thank you so much for taking the time to talk with us. You have a very exciting program and we are looking forward to seeing the findings from your many students and also from your extension

Elsa Youngsteadt: program.

All right. Thanks a lot. This has been fun.

Gardening and landscaping for urban wild bees is growing. While there is a lot of attention to the flowers to help bees, what else drives diversity? Also, how is diversity measured? In this episode we learn about the broader factors that determine diversity and the biases involved with measuring bee diversity with pan traps.

Dr. Elsa Youngsteadt is an Assistant Professor and Extension Urban Ecology Specialist at North Carolina State University. She is an insect ecologist interested in how urbanization and climate change alter the interactions between insects and other organisms. She is committed to conveying research results to audiences who can use them through Extension and outreach. Her non-science interests include running, cat training, and gardening.

Links Mentioned:

Dr. Youngsteadt’s Book Recommendations:

  • Currently reading: Chittka, L., 2022. The Mind of a Bee. Princeton University Press.
  • Recommend: Danforth, B.N., Minckley, R.L., Neff, J.L. and Fawcett, F., 2019. The Solitary Bees: Biology, evolution, conservation. Princeton University Press.

Dr. Youngsteadt’s Go-To-Tool: Bee squeezer

Dr. Youngsteadt’s Favorite Pollinator Species: Eastern Carpenter Bee (Xylocopa virginica)

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