Transcript
Speaker 1: From the Oregon State University Extension Service, this is Pollination, a podcast that tells the stories of researchers, land managers, and concerned citizens making bold strides to improve the health of pollinators. I'm your host, Dr. Adoni Melopoulos, assistant professor in pollinator health in the Department of Horticulture. The days are getting longer, so it's time to start thinking about mason bees.
Soon we're going to be getting our mason bees ready, and putting them out. But you know, where do they go? What are they feeding on? We always assume that they go to our apple trees and they're pollinating our apple trees. But if you walk around your garden, you'll see that they're going to other places. But where are your bees foraging?
Is it important in terms of their overall health? This was a great opportunity to bring back on the show Lila Westreich. She's a PhD candidate at the University of Washington, Seattle. She's doing a great study up there in urban environments and looking at how the bees do in different environments, but also what they're feeding on.
And as you'll hear in this episode, what kinds of disease they're encountering in those different environments. But since we are talking about mason bees, I did want to put a plug in. Beevent 2020 registration is now open and the keynote speaker is going to be Olivia Messenger Carroll, who is the co-author of Bees in Your Backyard. It's going to be March 7th at the Lynn County Fair and Expo Center. Registration is $30. It's now open. Please register early and help the organizers. I'm going to put the link to the registration in the show notes, but you can also go to OSU Extension and just type in the search engine, Beevent 2020, and it'll come up. And we're going to be there and I hope to see you there. OK, hope you enjoy the episode. OK, we're here with Lila Westreich.
Welcome to Polynation again. Thank you. And number catch up on your research that we talked about in, I think, in an episode last year or a little bit further back.
You're a lot farther along right now. We're at the Orchard Bee Association meeting and you gave an update on some of your research with Mason Bees. And I guess one of the things just to start off in sort of the relevance of your research is like there's a study that came out in Oregon with cats. They put a little camera on the cat. It's like it was really surprising where the cats went.
Yeah. It's like, oh, the cats went there. And I guess when we have Mason Bees, people are going to be putting these out and we just have all sorts of theories about where these Mason Bees are going. But tell us a little bit about how you've gone about answering this question of like where the Mason Bees are going in an urban area.
Speaker 2: Yeah, it's a good intro. I was asked by a reporter recently why this matters. Yeah. And I almost didn't have an answer. It was like a heartbeat before I could think of an answer. Yeah, we want to know where they're going.
So that's kind of the big question. I have sites across Seattle and kind of the outer surrounding area where we place bees and then we allow them to forage, grow up, nest in those places. And then once they deposit their nests and complete them, we pull the nests, open them up, and take the pollen from those nesting tubes. And it's a complicated thing to describe rather than see, but basically we get tons of pollen, all unique to the different sites that we place the bees within, because the bees have this very short foraging range so we get a really good data set out of it. And so we sequence the pollen and then we're getting kind of a relative abundance of where they're going, how much they're going, what species are kind of dominant across different sites and how those different sites vary regardless of what's planted around them. We get a lot of different species coming out of everything. Yeah.
Speaker 1: OK, so let's just go through this again. So the bees, so there are for those people who haven't kept mason bees before, you can keep them in these little paper tubes.
Speaker 2: Yes, these nice, they're they're easy to transport, easy to convince to nest in your yard. I personally use this like a cheap PVC option
Speaker 1: Because sewer pipe, I believe it is. Yes, yes, exactly. Beveled sewer pipe. It works great. So you've got the little straw, the paper straws that are inside it.
Speaker 2: OK, yeah. And we place bees in a little emergence tube just underneath and we drill a hole and the bees can then come out of their little cocoons that they overwinter and come out of the hole and then nest right in that. They look up and there's a bee hotel right there waiting for them. How did this happen?
Speaker 1: Yeah, so lucky. OK, so they come out and so they go on these forging trips. So they're going to fill the tube, as we know, with a little bit of mud, but they're going to pile up this pollen. But you can take that tube and you can get you can dig the pollen out.
Speaker 2: Yeah, so I interrupt them. So the full life cycle is they go out, they collect pollen, they bring it back to the nest. They lay an egg right in that pollen ball and then they seal off that little compartment. And so I allow them to do that for as many compartments as they want in each of those tubes. And then I grab the tubes and I throw them in the freezer and I stop everything.
And so that allows me time, first of all, as a grad student time. Time to pull them out of the freezer at my leisure, open them up take every single individual pollen ball, and put it in a little container. Yeah. And so once we have all that, which we're calling data, but I think a sane person would call balls of pollen filling your freezer. We can open them up, and extract the DNA from that sample. And so we're getting these individual samples that all relate back to one site, let's say, right?
So I've got 12 of these sites moving on to 24 this year, this past year in terms of our number. But each of those pollen balls can be sequenced. We can get an abundance of plants within the pollen ball from the DNA.
Speaker 1: So when you get the DNA out, it kind of like reads it back and tells you the species of plant represented in it.
Speaker 2: Yeah. Quinn McFredrick had the great analogy that I think I'm going to steal for the rest of my life, which is you can barcode it you can just the same way that you would scan something at the grocery store. And it would say, yes, that's one bottle of kombucha. It's 350. I can scan each of my pollen sequences and tell you, yep, that's a Salix. That's a willow species.
Speaker 1: OK. All right. So you've got this mound of pollen you've gone through. You've taken the DNA out. And throughout these different sites, tell us a little bit about the sites. These are all in the Seattle area.
Speaker 2: The data that I shared today. Yeah. This will change over the years, but the data I shared today was just within the 12 sites located within the Seattle Park system. So Seattle has been wonderful about letting me place boxes of bees in all of their parks with signs that they don't touch this.
And all of them are pretty different from one another, I would say. We're getting old landfill sites that have been converted into parks. We're getting beautiful forested, secluded, untouched areas that are full of native species and completely kept up over the years. And then we're also getting like mixtures of both of those situations.
So well taken care of, less well taken care of. And then kind of these sites where student restoration projects have been going on. So students put in a restoration site and then they graduate and they never come back and no one takes care of it.
And so it's not that anything bad happens. I don't personally and maybe we'll talk about why support only native species being planted, especially in these restoration sites. But we do see a lot of the nonnatives and invasives creep in. And a lot of them.
Speaker 1: OK, right. And I think we've had previous episodes where we've talked about things like hedgerows, you think, oh, you put the hedgerow in. No, actually have to keep the blackberries out continually.
Or it'll be a blackberry hedgerow. Exactly. OK, so so you've got this variation of variation of sites. So these sites will have some kind of mixture of different plants. And in some cases, some of them may be native plants. Some of them may be garden plants, some exotic.
Some of them may be like weeds that have sort of crept into invasive plants, which is a great snapshot of what happens in an urban environment. Exactly. All of those things exist in that matrix.
OK. And so I guess we're all dying to know. So when you looked at the pollen, you got your barcode scanner out. And you went to these 12 different sites.
Did you notice that? I mean, I think all mason bees like apple trees and, you know, they're mason bees. They're orchards. Did they is that all the pollen you found? Did they go out and seek out the apple trees in the backyard? And is that all you found?
Speaker 2: Not not even close. OK, all right. You're right that the landscape is kind of this mishmash of stuff in an urban environment. We do have apple species present. We found the apple in some of our sequences, and some of our site data. But at a very tiny level, the bees really at most of the sites dominated Salix, so Willow pollen and Rubus, which is it's a Rosaceae. Rubus is a hard plant to give you a common name for. It's the whole genus of like pink, blackberry, all kinds of berries, Dewberry.
Yeah. There's a lot of those in Seattle, a lot of native and non-native berries kind of all over the place, including heavily within the Seattle Park system. So those were the two really dominant species that we found. And I say species, but genuses that we found.
Speaker 1: OK, so these are the plants that they work. They were like Willow was not a plant that I, you know if I was trying to plant something to propagate mason bees, I would never have thought of Willow's.
Speaker 2: Right. It's funny because you go back through the literature. Now that you're looking for something, right? Yeah. I found in some of my sites, I found almost 70 percent of Willow pollen. And so I thought I'd never heard of this either. So I went back through the literature and it's been documented for almost as long as mason bees have been studied, that they go to Willow. They love Willow. But when we're talking about it in a bee-breeding sense, we're not usually talking about these urban environments. And so you don't always have a lot of Willow available in the middle of the field. Right.
Speaker 1: All right. Because most of the studies that are done on mason bees are done in agricultural areas where there may be two, or three plants they visit. But here you've got this amazing laboratory of like, so where would you go if you really wanted to go somewhere?
Speaker 2: Exactly. Yeah. And I think, you know, Willow is a tough species to grow. It's it's fussy. It's like wet soil. It's just not the thing you would think to plant in your garden. But it's the thing that grows and grows and grows and grows. And so in a lot of my sites, it's not necessarily the most dominant species. But the second I started looking for it, it was everywhere. I could just it's like it came out of the woodwork. I saw Willow everywhere I went in Seattle.
Speaker 1: It is one of those plants. I know lots of people don't like to have them on the property because they'll find the sewer system and they'll log it up and stuff like that. But it is a plant that's really easy to propagate and grow. And a lot of people who do conservation work, you know, because they're easy to propagate, they're easy to get in the ground.
And I think it's a real overlooked species when it comes to our pollinators in the Pacific Northwest. Yeah. And this confirms it. Yeah, definitely. That's great.
Yeah. So I guess another question would be from now you've got this nice resolution, this barcode scanner, and you're looking at the plants. There are a lot of people who think about native bees, they think about native plants. And so you have Ryebees and Willows. These are both native plants. When you break them down, how does that how does that figure into where they're forging?
Speaker 2: Yeah. So a lot of our native species especially the ones that grow within Seattle that I see in the park systems are these very small species, a lot of ground cover things or smaller flowering plants. We really don't have a lot of the big, huge meadow outlands out there. And so what we're seeing is mostly non-native plants. Most of what they're going to, if you were going to break down the pollen provision into native and non-native and invasive, you're getting mainly non-native plants.
Speaker 1: Well, isn't that that's a real surprising finding? OK, so non-native plants are these native bees have a kind of preference. And I guess that's, you know, doesn't necessarily mean that you know, they obviously evolve with native plants as a native bee, but they do have a broad preference that they can go to other other plants. And I do think it's kind of striking that the two groups that you found most representative have nothing in common taxonomically. So the willows and the Ryebees are in completely different plant families.
Speaker 2: Yeah. Yeah. We're getting a real breakdown of where they're going, and what they're preferring in each of the sites. And I know preference is tricky. I think the hardest part of my research is trying to think like a bee, right?
How would a bee look at this landscape and where would they go if they could pick anything? It's just impossible. The DNA data gives us a snapshot of what they're actually thinking, whereas just standing there and trying to count, you know, Okay, how many species of willow are there around me is so much more difficult I don't know if I'd even pick willow out of a crowd if I were trying to yeah Yeah, okay.
Speaker 1: Well, let's take a quick break. I want to come back and talk about how you also have measured in addition to Some of those tubes you looked at the pollen, but you also looked at how they Reproduced and all those things at these different sites. So let's come back and talk about that Okay, we're back with Lila so all right So you took some of these tubes you looked for pollen and then you looked at the other half of tubes for the reproduction and Occupancy, what did you find between these sites? Is there a difference between them?
Speaker 2: Yeah, we did find a difference Yeah, so to remind you we we kept half of those tubes in the field and allowed them to complete their nesting cycle Put them in the lab and let them chill out for a while to develop into pupa. We clean them off through an emergency chamber I'll let them stay in that little chamber at wintering temperatures basically It's it's like being outside, but in a tiny little box in my lab locked in a a
Speaker 1: big room Wait, just that this is really interesting just a little unrelated to the research, but you pick them up And you took them into the lab and then you put them in a where did you put them you put them in a fridge?
Speaker 2: We put them in it's basically a fridge that we program right we called it an emergence chamber because in my lab We use her insects emerging insects, but it's basically a tiny little box that we can put all of the different bees into and then allow them to Basically go into winter dormancy right they need cold temperatures and during those temperature periods they Drop down their body temperature Alongside the outside temperature. Yeah, eat up their fat storage over the winter Kind of like a bear. Yeah, I usually describe it like a bear They stay there for a while they wake up when it warms up and the song comes out and then they go off and do their thing Right same thing with the bees so we keep them there throughout the winter and then we put them in emergence bags Which are it's basically just a mesh bag We even have trouble because sometimes they eat through the mesh bags So it becomes a mesh bag inside of a big plastic tube And once they come out we
Speaker 1: I just I'll say we do the same thing we do emerge a lot of bees at OSU And in this group and they do have sharp teeth Yeah, and so we have gone to six mil plastic, but they only have one day and they'll get out of it.
Speaker 2: Yeah Yeah, we got to be fast. Yeah. Yeah, so what are the temperature regimes that you hold them at? What's the what's the how did you decide on that? So we decided there are a lot of different things in literature and experts have all their different Techniques we ended up doing a 10-year average of the Seattle temperature. So we took the high and the low For every day that it was recorded for the last 10 years
Speaker 1: and average them Okay, yeah, so we're vacillating our Emergence chamber vacillates between a 10-year high and a 10-year low So at night it's kind of a 10-year low and it's an average of those 10-year lows remember I'll be doing the day it moves up to an average of 10 years. That's a great idea. So that those are you know Over evolutionary
Speaker 2: time This is what they would have experienced. Okay, what a great idea Okay, so they've gone in there, and then what do you do next after the winter? So after the winter, those temperatures will start ramping up right naturally Getting warmer in the early spring the bees will start waking up and they're in their little emergence bag or emergence box They'll wake up they'll crawl out of their little pupa case and then they'll Basically buzz in our lab for a while.
We let them die off. We have to and then we sex the bees based on their Facial structure and body structure we also count the number of bees that fail to make it through that Emergence stage so sometimes the bees don't have enough fat storage and they die off during
Speaker 1: that's an adult So they're in the cocoon and you open them up and they just never come out because they run out of fat reserves, right?
Speaker 2: Okay, yeah, all right, and so we're measuring all these rates So we get what we call a success rate for the females for the males for the total bees You know how many bees actually made it through what proportion of them made it through the entire winter? And then a failure rate how many bees failed to make it through and these rates varied across the city so I talked about the park systems are all very different what they're eating is very different and What they're doing when they come out of those pupil cases The ratio of males to females is going to be kind of important because the second they get out of their case Their whole goal is to mate and start all over again, right? Yeah, So what we want preferably is a bunch of females and a Fairly large number of males enough so that there's some genetic variation in the offspring You know they're they're set up against diseases or pathogens that they might encounter But we would prefer more females to males or at least a 50-50 ratio, okay? And what we're seeing across Seattle is a ratio of much higher males to females
Speaker 1: This is not what you would want or even the bee it might not be optimal for the bee exactly as well Yeah, what what's making what do we know about why bees make males?
Speaker 2: So we know that and this is a little bit of conjecture the more science I get into everything the more I have to preface everything What we have seen is that in areas with lower nutritional content in their pollen? The bees will tend to lay a male instead of a female and bees are able to decide right They're able to choose whether they lay a male versus a female offspring contributes to this material, you know, I think honeybee is social Maternal community based on a female who's able to make those choices of am I gonna lay a male or a female today?
What do we need for the colony? Okay, and it's the same in solitary bees they can choose to lay a male versus a female and We have seen this this lower nutritional content lead to more males
Speaker 1: Okay, so that's what we know in the literature and you're seeing at some of your sites, not this ideal 50-50 mixture But they're skewing it much higher to the males, right?
Speaker 2: Okay From your nutrition analysis are you able to sort of piece together? What do you know what makes a site where there are better sex ratios as opposed to these poor ones, right? We're starting to it's this deep dig So we've started with our nutritional content work by just digging through the literature and trying to find Essentially what have other people found with the pollen that they're collecting in mass, right? The salix pollen they're collecting a ton of salix pollen What does salix look like in the literature for people who've done these really in-depth amino acid content assays?
We don't have it yet. It takes quite a long time to do that and I want to be sure before I make any assumptions about it, but It's it's so variable There isn't like this one pollen that is definitely terrible for the bees But they visited anyway Yeah, or this one pollen that will just save the bees and it has everything you need like a like a milkshake that has every Nutrient you need there's none of that. There's this crazy variation across We do know things like brassica pollen has very high protein content But there are too many variables to assume the species that I'm visiting So the hope is that we can do this really an expanded nutritional analysis of the pollen we're collecting this year Submit it to a nutritional lab and get an actual amino acid breakdown of the pollen Yeah, I think that'll lead to a lot more answers in these these big Absolutely.
Speaker 1: Yeah The last thing I do want to ask you about you also are it's a really expansive project There are so many tentacles, but you also are working on the diseases and we've heard we've heard from others Guests who've talked about bee diseases in the plant community that surrounds them Just give us a flavor of what you're doing there and where you're hoping to take it.
Speaker 2: Yeah The 2018 work also included this bacterial chapter We know bacteria can be beneficial and detrimental to the bees. We know their microbiome is really important the same way ours is I have been essentially doing the same thing with the plants the sequencing with the bacteria. So you can do the same thing Using a very different region of the DNA to look for a bacterial identification bacterial scanner What we're finding is tricky. It's hard to see much of the bacteria in Seattle and some of that is just the nature of sequencing sometimes it doesn't work Or sometimes it doesn't work as well as you want it
Speaker 1: to the bacteria may be there But it's just the techniques very tricky
Speaker 2: the techniques are tricky and it's not that our technique doesn't work. It's just that We need that one extra punch to get a little bit more data through and so The preliminary stuff that I presented today was we did identify a couple of different bacteria that have been associated with bees in the past And this work hasn't been done in western Washington hasn't been done Seattle for sure And these bees are pretty prevalent in a really wide area And so they're picking up a lot of stuff anything they're picking up Is going to come with them back to the nest and we're hopefully going to be able to sequence it and identify it But of the things we've got a lot of it's associated with soil that makes sense, right? They're they're nesting partitions or soil on either side.
Speaker 1: Oh, I hadn't thought about that. Yeah, they're gonna be picking up bacteria from the soil Definitely.
Speaker 2: Oh, yeah, of course. Okay. Yeah, lots of plant bacteria They're picking up, you know, the mothers are forging on different plants picking up whatever's on that plant Whatever's on the surface of the flower when she picks up her pollen and then deposits his back with the larva and we're getting a little bit of Uh Potentially parasitoid related Bacteria again, it's so hard to say with these really low levels of the results that we've got but I think it points to a potential for Maybe a health-oriented Hypothesis right we're seeing a lot of different bacteria at some sites versus others. Why? That's what's driving that? Is it the plants that they're foraging on? Is it the nature of the Seattle landscape?
Maybe there just isn't a whole lot out there So there are a lot more questions than answers that I've discovered from last year's data but Next year we'll help to expand this and do more sequencing and fix those little Techniques issues and hopefully get a huge data set of all the bacteria that are being visited in the area
Speaker 1: This is really remarkable and it's really great. This is the Pacific Northwest. I think for uh Our listeners in Oregon and Washington. This is uh, I can see I can see the horizon of where this can lead to some Better choices in terms of like how to create A habitat for mason bees and I know there are lots of people in this region that are having mason bees in their backyard. So yeah, definitely.
Speaker 2: Yeah, I think a lot of my talks are to the general public A lot of the general public are concerned about their park system. They want to know what to do and even think about Some of the parks in Seattle are filled with this invasive Hawthorne, right? Oh, right and one of my kind of smaller questions was well are the bees visiting this invasive because if we go out We decide okay, we're gonna fund this Very expensive program to eliminate all invasive species in this park and it's mostly Hawthorne If we spray all of those Hawthorne's they all die off.
What's that going to mean for the species who potentially rely on it? Absolutely So I'm pulling out a lot of those little trends in my work that yeah, they are visiting a lot of these species And if we're gonna pull them out, what does that mean for what we're gonna plant in its place?
Speaker 1: Right because you've got More than just visitation at one plant you have you know the community so you can say well it may need You to sort of bump up some of the willow plantings.
Exactly Yeah, yeah, and I just love willow just I think about a lot of our Queen bumblebees coming out in the spring, but also all the mining bees willow is such an important Early spring plant for honey bees as well. Right.
Speaker 2: Yeah, everybody is good everybody loves them. Yeah, definitely. Yeah Well, thanks so much for taking the time to tell us about your research, and then we look forward to The third part in the trilogy after you defend it. Yeah, thank you very much.
Speaker 1: Yeah Thank you so much for listening the show is produced by Quinn Sinan Neil Who's a student here at OSU in the new media communications program and the show wouldn't even be possible without the support of the Oregon legislature The foundation food and agricultural research in western serre show notes with links mentioned on each episode are available On the website, which is at pollination podcast dot oregonstate.edu I also love hearing from you and there's several ways to connect with me The first one is you can visit the website and leave an episode-specific comment You can suggest a future guest or topic or ask a question that could be featured in a future episode But you can do the same things on Twitter Instagram or Facebook by visiting the Oregon bee project Thanks so much for listening and see you next week
Many of us put mason bees out in our backyard or farm. But when they leave the nest, do you know where they are going to forage? In this episode we hear how a sleuthing graduate student in Seattle is beginning to piece together a picture of what resources these bees are actually using.
Lila Westreich is a PhD candidate at the University of Washington, Seattle, WA in the Department of Environment and Forest Sciences. She has a B.S. in Plant Breeding and Genetics from the University of Minnesota. Her research focuses on the effect of varying landscape composition on the solitary mason bee, Osmia lignaria. Her research with mason bees was previously featured on Episode 74.
