76 Dr. Chelsea Cook – Honey Bee Scouting and the Virtues of Being Easily Distracted (in English)

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. On Pollination, we generally encourage our listeners to cultivate a laser sense of attention to all matters pollinators. But today we're going to be talking about the virtues of being a distracted pollinator. Dr. Chelsea Cook is a Ruth L. Kirsten Postdoctoral Fellow at Arizona State University, and today she's going to be talking about some new research she has coming out about how honeybee scouts have a real sense and a real taste for novelty.

They're easily distracted and that's plugged into the broader strategy about how honeybees are so successful in finding new patches of flowers in a changing and dynamic landscape. Finally, I just want to make a quick plug. Registration for the first Pacific Northwest Pollinator Summit and Conference is now open. You can register today by visiting OregonBeeProject.org, backslash PNWPollinators 2018.

Speaker 2: Thanks for having me, and don't be happy.

Speaker 1: I'm really excited to have you. It was a former guest who said, oh, I really need to reach out to you. You're doing amazing, interesting stuff. So I'm really glad to be catching up with you. And we've heard in past episodes how there's a real cost saving when a bee learns to handle a flower and their incentives to return to the same flower. Because of that, it's just like you learn it.

It's like the monkey barge or something. You know how to get in and out of that flower. But the patch of flowers that yielded nectar and pollen one day might fade the next. They don't just stay there. So can you say a bit about the trade-offs honeybees face when confronting this dynamic floral landscape when they zoom out of the hive?

Speaker 2: Yeah, and that actually is, that's the dilemma that bees constantly face. So I like to think about this kind of from a human perspective. I imagine that if in my neighborhood, like every couple of days, the grocery store just closed and then popped up somewhere else.

Right. So like, how would you, how, how would you deal with that? So I think this dilemma of just always trying to stay aware and be aware of where food could potentially be is a dilemma that bees face and they have to work in order to make sure that they're, they're always collecting food because there's so many individuals in the colony that they have to feed everyone. So yeah, when I think about this, I think of the grocery stores opening up and closing in your neighborhood. And this is the type of food landscape that bees have to deal with every day. Sometimes, flowers have different plants, and flowers in general have different times that they're open and closing on the duration that they're staying open and closing across days or weeks. And bees have to learn how to deal with that. And I think that also when bees have to search the environment, they are dealing with things like predators. So, oh yeah, right.

Speaker 1: When, yeah, so when they're, it's like the grocery stores are opening and closing and then there's somebody like lurking.

Speaker 2: There's like the ghost and Pac-Man, right? You're like searching for the grocery store. But there's, yeah. So, I mean, and, or if like you walk into a new grocery store and you're just like, you know, there's some like monster who could potentially eat you or I mean, this new grocery store. So yeah, I think that like when, when it's, when you find a patch that is really great and there's no predators, you can stay there. But we know it's only going to be available only for a short period of time.

Speaker 1: So you're going to have to move on, even though that would be the best situation. The grocery store right there, no Pac-Man monsters or ghosts. And I can just gobble up nectar and pollen.

Speaker 2: Exactly. Yeah. And so yeah. And so this is something that when you're searching in the environment, there's this trade-off of being able to, and not only the food availability but what other aspects they could potentially encounter. And then also just the time that bees have to search in the environment. I mean, who knows, like maybe the grocery store closes and you can't find a new one. Like what happens? I've been there. Right. Yeah.

Speaker 1: I live in downtown Phoenix. I just wander around. Okay. Well, there you go. Yeah. Downtown Phoenix is a little bit of a food desert. And so there's like, yeah, it's a little second, sometimes be hard to find your grocery store.

On a past episode, we had Margaret Cuvillon and Roger Search, who talked about this remarkable feature that honeybees have specifically and really surveying the neighborhood. Absolutely. And keeping track of things. And can you just remind us there's a division of labor between these bees that are going out and finding stuff and scouting it and also the bees that follow them? Can you tell us a little bit about that?

Speaker 2: Absolutely. So I love, I love Margaret and Roger's work. They're really great scientists. Yeah. So we have the bees who are going out, they're searching the landscape. They're finding food. They're coming back.

They're performing the waggle dance. Right. And those bees are typically the scout bees. So they're the ones doing the searching. They know that their grocery store is going to close.

They need to find a new grocery store. So those are, those are the scouts. And the recruit bees are the ones who are watching this waggle dance. And they're the ones who are going to exploit that food source, that new grocery store that they find. So the scout bees have found something new. They come back, they do the waggle dance, they say, let's go. The recruits go out and they're the ones who are going to persist over and over and over again until that grocery store closes.

And I'm still kind of keeping with that analogy. If you're an individual, like you and I trying to find a grocery store, we're the ones who have to balance both finding it and collecting enough food from it before it closes, right? But, in a society like a honeybee society, you can have this division of labor where an individual can be the one who finds it. And then they're also still in charge of continuing to search the landscape. Well, then you pass the responsibility of exploiting that resource and collecting enough food for the entire colony.

So it's a little bit, and if you think about like just like kind of group dynamics and existing in a society like that, it may be more beneficial and easier for a whole society to divide that labor rather than just have one individual doing both the exploration and the exploitation.

Speaker 1: All right, cool. So you've got a new paper out. Yeah. And you have this hypothesis where you thought that these, you know, these different approaches of scouts and recruits might function to square off this trade-off just in the way that you described. This trade-off between should I stay or should I go? Absolutely. Tell us a little bit about your hypothesis.

Speaker 2: Yeah. So we, this hypothesis came kind of in both, in kind of both directions, kind of from the behaviors that we saw in the lab and the behaviors that we see, like the ecologically relevant behaviors that we see on bees performing. So, we know that there is this division of labor that scouts and recruits are doing these different jobs.

And the question is how, like what drives this division of labor? And then in the lab, my previous work which has come from my lab, focused on this behavior called latent inhibition. And late inhibition is just kind of a fancy way of saying learning to ignore familiar stimuli. And so, yeah, we have, we know that in a honeybee foragers, if we collect a random assortment of honeybee foragers, some bees will exhibit high-late inhibition where they're good at ignoring familiar stimuli. And so ignoring the familiar stimuli and paying more attention to novel stimuli. And there are some bees that learn and pay attention to familiar and novel stimuli of the same. And so we see, we know that bees exhibit foraging bees exhibit these differences.

And we know that there's a division of labor in the, in the foragers. So we're just trying to figure out what exactly is the, that maybe the, there's a connection between these two behaviors. So this lab-based learning behavior and this foraging behavior. And so the hypothesis there was, are these behaviors linked?

So the hypothesis was maybe the scouts are the high LIBs. They're good at ignoring familiar stimuli. And they're, they're good at ignoring where they've already been to pay attention to novelty or where they were something new and exciting in the landscape. Whereas the recruits, you'd want them to be excited about new, maybe if they stumble upon something new, but you still want them to be excited about familiar. You want them to be excited about places they've already been. And yeah, so you see, so this was the, the kind of link that we, this first hypothesis is like, okay, maybe the scouts are going to exhibit this high latent inhibition where they ignore familiar and get excited about the novel. And the recruits will be excited about growth. Okay.

Speaker 1: That's very cool. Let's take a break and I want you to come back and tell us whether this was the case because this seems fascinating that you'd have bees that were specifically highly distracted. Yes. We'll be back in a second. Okay. Before the break, you told us, that this hypothesis of latent inhibition, this distraction in scouts may explain why these bees are more predisposed to finding novel floral sources and searching the neighborhood for these newly opening grocery stores. Can you walk us through how you performed your experiments?

Speaker 2: Yeah, absolutely. So the first thing we had to do was essentially give the bees a novel foraging environment. So we did a pretty typical hive moving assay where we moved, we sealed up the colony the night before. And then that night we moved the colony. It was all sealed up the next morning.

We opened it up and we allowed the first bees to leave. And actually, as we, as they left, I marked them with colored chalk. So I could keep it, and I changed the colored chalk every 10 minutes. So I knew the time chunk that they left. And so I essentially was just like, if you're gone for, if you leave the colony and you're gone for 10 minutes and you, that, that means you've been exploring and foraging in this novel landscape and doing your exploration. So I would call those bees scouts and they were unable to get back into the colony when they came back. So I know that there was no recruitment happening. So no one was going inside and performing the waggle dance. Gotcha. So every bee who was leaving was experiencing a new landscape. And they were, I was assuming that they were doing scouting behavior.

Speaker 1: Okay, gotcha. Exploration behavior.

Speaker 2: Then I opened up the colony. I let them freely for, I collected those bees. We brought them into the lab. The scout bees brought them into the lab, and performed a behavioral assay on them, where we pre-expose them to an odor. So we blow the same odor at them for three and a half hours. Every five minutes they get this blast of odor. And this is the pre-exposure. So we're familiarizing them with this odor. And during this time, at the same time, the bees outside, I've opened up the colony and they're freely foraging. So we have scouts, recruits, everyone kind of.

Speaker 1: They're learning this new neighborhood. Exactly. They're learning the new neighborhood. They're finding the new grocery stores. So in the lab, we're doing this, this behavioral assay. So we do this pre-exposure and then we test their ability to learn that familiar odor that we've pre-exposed them to and a novel odor. And so we do this by doing the proboscis extension reflex. And this is a behavior that you can use. Essentially it's classical conditioning like Pavlov's dog.

Speaker 2: So you blow an odor at them. And at the same time, you touch their antenna with sugar water. OK. And their tongue comes out and you feed them, you give them a little reward. And so over, like they've learned this so quickly within one or two trials, the bees have learned the odor. So as soon as the odor starts to blow, they stick out their tongue without the reward. Or just like the salivating dog. Just like the salivating dog. Exactly.

You ring the bell, the dog starts to you give the food, and the dog salivates. Exactly. OK, gotcha. So yes, we're doing the same thing with the bees.

What we're doing is trying to evaluate how well the bee learns that familiar odor, and how quickly it takes them to form that association with the familiar odor compared to the novel odor.

Speaker 1: Oh, right. I can see how this is. I can see where this is headed. So if you were one of the, if you had this latent inhibition, you were kind of predisposed in that way, then you'd really, as soon as you got something new, you'd be like, oh, what's that? Yep.

Speaker 2: Exactly. And then, yeah, and if you're a scout bee with a familiar odor, you may be like, I don't really care about that, but this new thing is really great. OK, what a great way to test this.

Yeah. So when we tested the, we did the, we did the same thing with the scouts. So we did the scouts one day, the next day with the same colony after everyone had been foraging and there had been waggling and recruitment happening. We went out, we collected foragers that we assumed were recruits. Tom Sealy has done a lot of work with scouting and recruiting behavior. He shows that typically around 70 to 93 percent of the colony is of the foraging workforce are recruited bees.

Speaker 1: Oh, so when you do that first little first little, you've got a higher likelihood.

Speaker 2: Exactly. That group is guaranteed to be scouts because they're the ones leaving first and nobody's being recruited because we prevented them from going back on. Exactly. Yeah. So we assume that the bees the next day, most of them are going to be recruited. We do this assay again and we see that the scouts are better at they do not form that association with a familiar odor.

Really? Learn the novel odor very quickly. The recruits, however, learn both the novel and the familiar odor the exact same. So they're learning curves. They form that association in the same way. Novel versus familiar recruits are on it with their scouts. The scouts ignore that familiar odor and they learn that novel odor very quickly.

Speaker 1: Wow, that is amazing. That's really great that you have a hypothesis and it turns out so well to explain.

Speaker 2: How often does that happen?

Speaker 1: Not that often. So that's a really, really perceptive and sort of forming the hypothesis to begin with.

Speaker 2: Yeah. And was really what was great about is it was informed by both taking this kind of like this learning behavior kind of rooted in really just kind of rooted in human psychology where thinking about latent inhibition, which is not really even been studying in bees for that long. In fact, the first study that came out about latent inhibition in nineteen in the 1980s, so bees didn't actually have this association.

They couldn't learn in this way. And then subsequent studies show that they actually could. So we have this really like lab-rooted behavior and kind of just trying to apply this to this ecologically relevant behavior. I think that that was the kind of both directions coming to this hypothesis that we could effectively test.

Speaker 1: I'm dying to ask you two questions. The first one is you wonder how this comes about if it's just like if there if it's just you're the first one out in the way that the experiments run, the first one out sort they sort themselves out is just a matter of order or whether there's a genetic predisposition.

Speaker 2: Wow, that's such a great question. And yeah, I think that that's a place we're trying to go. Associated with this study, this paper, we did find that the scouts had higher levels of tyromine in their brains compared to recreates. Tyromine. Tyromine, yep, it's a neurotransmitter.

Okay, all right. So this is a neurotransmitter or in this paper, we refer to them as biogenic amines, a fancy wave saying neurotransmitter. And it's a neurotransmitter that's specific for invertebrates. So humans have mammals and human, vertebrates have it in smaller amounts, but it's a really, it's a huge, hugely important neurotransmitter in invertebrate behavior.

Especially in honey bees, plays a big role in social behavior. But we haven't tested that causally yet. So we did see this association, but again, we don't know if it's because they were the first ones out and they just have an elevated, the scouts have an elevated tyromine amount in their brains or the, and that caused them to go out or that they just have it as a result of being the first ones out. So we don't know kind of the causation of that yet, but we're working on trying to figure out if is this a genetic, genetically based behavior.

As far as scouting and recruiting go, the late inhibition behavior is, we know that it does have some genetic component. So in some other experiments we've done, we've selected queens and drones. With this behavior, we've collected, we've selected high queens and high drones, low queens and low drones, made them, and made workers that were high and low. So we could do some larger scale field tests with bees that we know they're learning background, they're a genetic learning background. And that works out pretty well. So we know that there's some association.

Speaker 1: I can just imagine if you were able to select in a direction where everybody was just totally constant, they'd just be like showing up.

Speaker 2: Just everything. The store was here, it was here. It's just like, come on. I'm not changing, I'm stuck. I'm sure there are. I mean, yeah, people have done studies on persistence and they've like removed a feeder and like hours later, there are still bees like, but it was just here. Oh my God, come on.

Speaker 1: The tree was there, the swing set was there, and food was right there.

Speaker 2: Yeah, it was all these landscapes, it was here. I promise guys, yeah. You're just like, trolling bees, let's, yeah.

Speaker 1: So you talked a little bit about the next steps for your work, but is there something else, are there other directions that you're hoping to take this work in?

Speaker 2: Yeah, absolutely. I think what I am really interested in is this social, this kind of individual and social level cognition and that interaction between this like individual level physiology or genetics that shapes like this kind of proximate learning behavior, but then how this translates into more ecologically relevant behaviors and testing this across many bees. So I'm interested in kind of translating this to other social bees, but then also in solitary bees. How does their cognition change when they don't have to divide labor when it's just one individual, for example, doing these types of behaviors, kind of like what we were talking about?

Speaker 1: Oh, they'd have to integrate all of this kind of into one little critter.

Speaker 2: Exactly. And so how is that cognition different? How does that, when you get to share jobs, is that easier for an individual and does that kind of reinforce social behavior? Or are you like, you know what, I'll handle this myself. And that kind of reinforces more individual behavior. So yeah, I'm very interested in kind of doing some more comparative work across other social bees and even solitary bees.

Speaker 1: I should be really cool. You know, I was always wondering about this. Are our solitary bees smarter?

Speaker 2: Yeah, I know, right? You're like, you just have this giant brain and you don't share it with anybody.

Speaker 1: Like, what are you doing? I remember in Wealth of Nations and Adam Smith, he has this thing where he says, like, you know, there's this new manufacturing. In the old days, they had to make a pin. You had to do it all. And they were kind of crappy pins. But you knew all the steps. But now there's just one guy who just cuts the pin. There it is. That's all they do. And he says like, it's all he does, but he can't do anything else.

Speaker 2: Yeah, it's like a jack of all trades or just like the master of one, right? It's like a trade-off. Like you're just good. Yeah, and this is like, it's so funny in like a honey bee colony as you do have one bee performing that one job, but she goes through all these other jobs throughout her lifetime.

So she just specializes for like a couple of days max, right? So even in that situation, it's kind of again, like this predisposition of cognition to potentially shape this behavior that you're going to do for just a little bit of time. And then kind of just like the cultural information that ends up being shared about that. Bee colonies, if they're not being moved that often, they do have this like they're sharing, or social insect colonies in general, will kind of share this cultural information of where things are.

Speaker 1: Oh really? Where foraging, yeah. Well, I imagine they must. Cause it's kind of like this information is just gathering and gathering. It must accumulate.

Speaker 2: Absolutely, yeah. So there's definitely some, how do those brains and those different bees work? And then I'm trying to break into the behavioral genetics realm as well. So like we're talking about like what actually makes these bees want to do these different jobs. And I want to get to the genetic mechanisms of those too. So I want to flesh out this learning, this kind of predisposition of learning behavior, and try to figure out if there's some genetic underpinning to that as well.

Speaker 1: Oh, because a honeybee colony is not just genetically uniform. Exactly. They've got a lot of heterogeneity. So there may be a way in which that helps structure. Exactly.

Speaker 2: Oh, okay. And so yeah, so are these bees that are high allies who are likely to go on to being scouts? Do they have some, is it, yeah, some gene expression or some genetic background that kind of causes them to be just predisposed in this way versus the recruits? So I'm still gonna figure that out. But yeah, hopefully, that's my next. Yeah.

Speaker 1: Okay, well, let's take a break. We're gonna come back. We ask all our guests these questions and are curious what your answer is gonna be. Sounds good. Okay, so we ask all our guests if they have a book that they recommend. And I have, it's funny, I've done a bunch of interviews now with people who are either postdocs or graduate students. They all say books, I'ven't seen a book in ages. Yeah.

Speaker 2: Oh yeah. Reading is hard.

Speaker 1: So I don't mean to put you on the spot, but do you have a book that you'd like to recommend to our listeners?

Speaker 2: Yeah, absolutely. So I actually reading is one of the kinds of things that I like to do to relax. I try to squeeze in a little bit of fun reading every day.

Oh, great. So yeah, so I do, that's something that I love to read. So I can't, I, science papers are great, but I love books. I'm actually reading a book right now called Behave by Robert Sapolsky. Robert Sapolsky is a human and primate neurobiologist.

I think he's at Berkeley. This book essentially traces behavior through kind of all the proximate and ultimate levels of a specific behavior. And then he interweaves the environment that shapes the behavior.

Speaker 1: Okay, you have to explain what proximate and ultimate are.

Speaker 2: Totally, yeah. So he goes through, he's just using behavior in general. So he brings up aggression or something. So some stereotypical behavior. And he addresses it through the seconds before this behavior happens, the minutes before. So this is kind of the physiological stuff and an animal's body that happens to cause a behavior.

The days before, the weeks before, the months before, the years before. And then getting into the ultimate causes when we were talking about the generations and how evolution selects on the why and how a behavior happens. So it's really fascinating. I mean, it's such a fascinating count of behavior. And because he's a neurobiologist, he gets really into the details of what's going on in the brain.

But he's always talking about this in terms of the environment. So if you're different from the different genders and the different hormones that could be going on in your body, like the testosterone or estrogen that is going on in your body how that can change behavior. Or the social context that your behavior happens in. So aggression can be beneficial in some social environments, but not beneficial in others. So it's really like the all-encompassing account of behavior.

And it is just like drills into behavior. Robert Sapolsky is amazing. I'm not getting paid by him or anything. Maybe he'll hear this. He's in Berkeley, so I'm fangirling right now.

Speaker 1: Well, I love the way that you sort of set it up because doing it by time, you move outside. Obviously, you have a certain, you live so long. So there is like the forces that shape, how these things happen in that environmental context, but also evolutionary time.

Speaker 2: Absolutely. And so yeah, it's great, he does a lot of his lectures, and his behavioral neuroscience lectures from Berkley are free on YouTube as well. And he's done several TED talks. He's a great science communicator. And this book, as he tells you like, oh, if you're not super into these brain regions I'm about to talk about, you skip to the next paragraph. So it's really for all levels of people who are interested in behavior. Fantastic.

Speaker 1: It's really great. Great recommendation. Yeah, thanks. All right, the next question I have for you is for the work that you do, do you have a go-to tool?

Speaker 2: I don't have a go-to tool. I have a go-to method, which is making things. I love the creativity that performing experiments allows you to have. And I am a huge fan of just kind of going to the hardware store, going to the craft store, and putting things together.

Speaker 1: I can imagine when somebody says, can I help you? Oh my God. I don't know.

Speaker 2: I need to mark, yeah, I've said this before, like at the craft stores, people are like, what are you using these markers for? And I'm like, do you really want to know? I'm going to be marking honey bees.

They're like, what do you do? Like, yeah, that's who I am. But yeah, I've done a lot of experiments like really on the cheap. Like I'm so frugal when it comes to doing experiments. I'm always trying to figure out the easiest and cheapest way to kind of do stuff. Like doing, for example, when I was doing the marking, the bees as they left to mark the scouts, it was just colored cornstarch that you get.

Like there's been those like 5K color runs where people are all colored and dust, yeah. So I just ordered those on Amazon. I think I got a package of like 30 for like 10 bucks. And the little foam rollers from the hardware store that I dusted the chalk on and kind of set it up at the entrance and they walked right by and dusted themselves and it was great.

Speaker 1: Michael should have like a citizen science sector. Totally, absolutely.

Speaker 2: Like from side, these weird people have come in and asked for this before. Try this, try this thing. These markers are great for bees, for marking bees.

Speaker 1: Well, it does, you know, I think of a lot with Honey Bee Research, there's a lot of discoveries that were made by just patient observation and some paint.

Speaker 2: Oh my goodness, I know. It also even just the paint that you use, like how many people have gone through marking bees with something that they don't like and or even just the tags that you use, the glue on the queen, we'd call them queen tags, like those little tags with the glue and they hate it. You have to like hold them down until the glue dries. Yeah, there's so much. Yeah, it's like you stand on the shoulders of giants, right? And the giants really are trying to figure out, are the people who have figured out these little details of what paint works and what glue works. And yeah, because of this work, especially for behavioral work, it's really important to get those details right.

Speaker 1: You know, you read like the dance language of the Honey Bee and like that, a curious individual with not a lot of money could do those experiments again.

Speaker 2: It's great. Yeah, you just need time, right? That's the... Don't need a lot of money, but you do need some time to be able to do, yeah, to do those kinds of experiments.

Speaker 1: There should be a classic experiment in apiculture that you can do in your classroom. That should be okay.

Speaker 2: Yeah, I'm sure like Margaret and Roger talked about the angles and how in the waggle dance, just figuring out the angles that they're waggling at and where they're going. Yeah, I mean, people have translated that. That's like a translation of the bee language, right? That's crazy.

Speaker 1: Very cool. Okay, so the last question I have is, is your favorite bee, the Honey Bee?

Speaker 2: My favorite bee is, well, I mean, it's like your kid, right? Like I don't wanna... I'm sure other people have said that. Yeah, yeah, for sure. I do love Honey Bees.

I think they're a great model system, especially for trying to understand social behavior and the evolution of social behavior. But since moving to Arizona, I did my PhD in Colorado and I grew up in Western New York. And I'm seeing the variety of bees, especially in warmer climates is amazing. We have this old tree in our backyard and xylocopa. I don't know the species, but I know the genocylocopa.

Speaker 1: The large carpenter bees. It's a huge black carpenter bee. Just looking for nesting sites in this tree, and I'll be out there reading my book in my hammock, my five-minute break when I get home from work. And I'll be out there and they'll just be out like they just come in and they're so loud and beautiful. And they're so curious and just like, you see them like hovering and just like zoning in on a little spot on a tree, just like a perfect spot. And I just love that, I love that behavior. So hopefully I'll be able to study them and get to know their brains a little bit more, which is my goal at some point. But yeah, I think those are my, right now, those are my favorite, it changes all the time. Fantastic. Well, now that you're in B-Mecca in Arizona.

Speaker 2: I know, it's great. So many bees, Africanized bees too. They're a little aggressive, but I still love them.

Speaker 1: Well, thanks for taking the time to talk with us today.

Speaker 2: Thank you so much for having me, it's been great.

Speaker 1: Thanks so much for listening. Show notes with information discussed in each episode can be found at pollinationpodcast.oregonstate.edu We'd also love to hear from you and there are several ways to connect. For one, you can visit our website to post an episode-specific comment, suggest a future guest or topic, or ask a question that can be featured in a future episode. You can also email us at [email protected] Finally, you can tweet questions or comments or join our Facebook or Instagram communities. Just look us up at OSU Pollinator Health. If you like the show, consider letting iTunes know by leaving us a review or rating.

It makes us more visible, which helps others discover pollination. See you next week.