Fri March 8, 2013
Getting the Springtime Buzz on Bees
IRA FLATOW, HOST:
You're listening to SCIENCE FRIDAY, I'm Ira Flatow. You may not tell by looking outside your window if you're in the Midwest, or snow has been dumped on you in the last week or so, but spring is really just around the corner, and with that comes blooming plants and buzzing bees. And what can we expect this spring from nature's great pollinators?
A pair of recent studies are helping us spring forward. Don't forget to do that this weekend, by zeroing in on some curious bee behavior. I don't know about you, but I need a cup of coffee every morning to help me get going. Well, it turns out that honeybees also get a buzz from caffeine.
In a study published this week in the journal Science, researchers found that caffeine found in coffee and in citrus plants - did you know you find caffeine in citrus plants - helps boost the memories of bees. And in an electrifying twist, a separate study published in Science found that as bees fly around looking for nectar, they can sense the electric fields in flowers. Pretty neat stuff, yeah.
Let me introduce my guests to talk about it. John Ascher is a research scientist specializing in invertebrate zoology at the American Museum of Natural History here in New York. Starting in June he'll be an assistant professor in the Department of Biological Sciences at the National University of Singapore. He joins us today in our studio. Welcome to SCIENCE FRIDAY.
JOHN ASCHER: Hi, glad to be here.
FLATOW: Little different department, in Singapore and New York. It's going to be a little different experience for you, I imagine.
ASCHER: It will be, but a lot of our work is Web-based, and so we'll continue doing a lot of it in the same way, just based in a different place.
FLATOW: There you go. Julie Mustard is an assistant research professor in the School of Life Sciences at Arizona State University in Tempe. She's one of the authors of the study on the effects of caffeine in bees. Welcome to the program.
JULIE MUSTARD: I'm really glad to be here.
FLATOW: Nice to meet you. Gregory Sutton is a postdoctoral research assistant at the University of Bristol. He is co-author of the science study on the electric fields in flowers, and he joins us by phone from Bristol, England. Welcome to SCIENCE FRIDAY.
GREGORY SUTTON: Thank you, thank you.
FLATOW: Julie, let's talk about - let's start with the caffeine study. What happens when bees get a little dose of caffeine, and why are bees attracted to caffeine in the first place?
MUSTARD: Well, that's really the interesting question because when we found out that there was caffeine in nectar, we were really surprised because caffeine's actually kind of a bitter taste to it. So we were really surprised that plants were actually putting it in their nectar because the whole reason we have nectar is basically to attract the insects to the flowers so that they will then pollinate the flowers, go to another flower of the same kind of plant, the same species, and take the pollen over there.
So we were like what's up with having caffeine in the nectar. And so that's when we actually started these studies to think that maybe the plants were using the caffeine to manipulate the behavior of the pollinators so that they are more likely to either learn about the flowers or to remember the flowers. And that's exactly what we found, was if the plants had caffeine in their nectar, that actually helped the pollinator, the honeybee in this case, remember the odor of that flower was actually correlated or was giving him a good treat, so they'd be more likely to go out and continue going to this type of flower, which would then benefit the plant via pollination.
FLATOW: Well, you know, those of us who have a cup of coffee in the morning say of course, right, you get a little caffeine, you'll go back for some more. Is it the same mechanism, do you think?
MUSTARD: Yeah, well, you know, obviously plant - bee brains and human brains are very different, but when you start looking at things like genes and proteins, then bee brains and human brains actually have quite a lot in common. So we suspect that the way that caffeine acts in honeybees is a very similar effect to how it actually acts in humans, where it has also been shown to help increase memory.
FLATOW: Now, you worked - a couple of plants you worked on. You worked of course in coffee plants, and we would expect those plants to have caffeine in them, but we would not expect, at least I didn't, when I heard that citrus plants had caffeine. Can...
MUSTARD: Again, we were really surprised about the citrus plants, and there's - coffee plants have caffeine and tea plants also have caffeine in their nectar and some plants that people use to make matte(ph), which is a very popular caffeinated beverage in South America, and they all have caffeine. So we were really surprised about citrus having caffeine, and again, that was one of the things that really gave us an idea that maybe the caffeine was there because the plant was manipulating the pollinator rather than it just being there as kind of a side effect from the rest of the plant actually expressing the caffeine.
FLATOW: Interesting, so what - where would you take this research further?
MUSTARD: Well, we're currently trying to figure out whether or not it's actually working through the same mechanisms that happens in mammals, in humans. So we want to look on the molecular level and see whether the same molecules are involved. We'd also like to look at other plants and see - there's at least 100 species of plants that should be able to produce caffeine and see whether the caffeine is also expressed in those plants' nectar.
And we would also like to see whether this will go back into the field and really study this more in depth about how the caffeine's actually affecting pollinator behaviors in general. So there's a whole bunch of really cool and interesting questions.
FLATOW: Cool is the right word, 1-800-989-8255 is our number, talking about things about bees you may not have known about. And John Ascher, what are the bees doing about now, this time of the year?
ASCHER: Well, we're just about to experience the big bee emergence. Right when the snow is melting, and it starts to warm up, and we start getting days of about 55 or 60 degrees and more, and you can be out in your shirtsleeves, that's when you start seeing a lot of bee activity. And people might not realize there are a lot of bee species right here in New York City.
Just in Prospect Park I found more than 100 species in my study.
FLATOW: A hundred in Prospect Park in Brooklyn?
ASCHER: Right, in a very urban area, and a small park at that, I mean relatively speaking. In New York City as a whole, we've documented more than 250 species, and we're still finding new species, and indeed species are still being described as new to science just as recently as 2011.
FLATOW: Can you tell the effects of climate change or global warming by looking at the bees?
ASCHER: We can indeed. We can see several effects. Among other things the bees are emerging earlier than they did historically, and we've shown that a couple of years ago in a paper in PNAS. And also we see an increase in so-called Southern species, species that reach their Northern range limits in this area or just a little bit further north, whereas the boreal species that are centered in Canada are actually decreasing.
These more Southern species are extending their range north and becoming relatively more abundant, and we've shown that in our most recent paper.
FLATOW: We've been hearing about, you know, bee populations are in trouble. They're vanishing. They're dying off in some of these colonies, colony collapse. Any good news on that? Is this still going on, colony collapses?
ASCHER: Well, colony collapse is very complicated. I think the best news is that that particular problem is specific to honeybees, and so our native bumblebees and all of our other native bees have a whole host of other problems, but they don't suffer from colony collapse disorder.
The other good news is I think that the researchers studying colony collapse have characterized this much better. They now understand multiple causes that contribute to this. But frankly, I'm not the person to talk about it, because I - to address this, because I really focus on the non-honeybees.
FLATOW: Yeah, because people think, well, bees are thinking about honeybees. But there are - how many different kinds of bees are there?
ASCHER: Well, I maintain a database, which is available at a biodiversity portal called Discover Life, and this lists 20,000 valid bee species.
FLATOW: Twenty thousand.
ASCHER: Worldwide, yes. And we know that this is just a big underestimate because there are vast numbers of new species that have not yet been described that we know about that are waiting in our collections for a taxonomist to have the resources to describe them.
FLATOW: That's more than many plants have different kinds of species.
ASCHER: Right, I think it's more than birds, mammals and reptiles put together. So it's a major portion of biodiversity.
FLATOW: Wow. Dr. Sutton, let's talk about your research now. You've found that bees and flowers have an electrical interaction.
SUTTON: Yes, yes, we did. Well, it's been known a long time that there is an electrical interaction in that the pollen in the flower is negatively charged, and the bee is positively charged, just friction from the bee flying around in the air makes it positively charged. So when the bee reaches into the flower, the pollen sticks to it, and it helps carry the pollen from flower to flower.
And what we found - what we wanted to know is could bees actually perceive this interaction. And we found that the bees could not only perceive but could actually perceive the electric field coming off of the negatively charged flower.
FLATOW: When you say perceived, what does that mean to laypeople?
SUTTON: Well, we found that if you gave bees a selection of 10 flowers...
SUTTON: ...of which five of them had sugar water and an electric field coming off of them, and five of them had a quinine solution, which bees can't smell but they don't like to taste, in the beginning, bees can't tell the difference. But after a while, bees can tell the difference between the electric-fielded flowers and the nonelectric-fielded flowers. And then if you just turn off the voltage, they can't tell the difference anymore.
FLATOW: Huh. Do some flowers have a much stronger electric field to attract the bees?
SUTTON: Different flowers have - different species have very different electric fields. One of the things we found is that the electric field on a flower isn't a simple thing. It's actually a complicated - there's charge distributed all along the flower petals, and that different flowers present a different-shaped electric field. And we've got data that shows that the bees can tell the difference just on the basis on the shape of the field.
FLATOW: Tell us about the - you did a very interesting experiment. You just described a little bit of it. Tell us about the rest of the experiment.
SUTTON: Well, the experiment was you put the bees in an arena...
SUTTON: ...and then you can give them artificial flowers, which in our case happened to be little discs with small plastic cups of nectar in them. And then we were able to fill half the cups with sugar water, which bees will do anything for. They absolutely love it - and half the cups with quinine, which they can't smell, but they don't like the taste of. And then you put - the cups filled with sugar water, you put them on top of a metal disc that's charged to about 30 volts, which is about the charge of a flower. A natural flower has about 30 volts of charge in it from the interaction - just with the - just the interaction with the atmosphere.
And then you have the quinine flowers have metal discs, but that's uncharged. You don't have any power attached to that. And then you'll see how long it takes the bees to learn to only go to the sugar water discs. And we found that after a while, the bees went to the sugar water discs almost 80 percent of the time, almost...
SUTTON: ...and they more or less ignored the quinine-filled flowers. And as I said before, the gotcha part of the experiment is then you turn off the power.
SUTTON: And then you see: Can they still tell the difference? And we turned off the power, and then it was back to 50-50. They couldn't tell the difference again.
FLATOW: They're getting a little frustrated by then.
SUTTON: Yes. Well...
FLATOW: Can a bee get frustrated?
SUTTON: ...it's hard to frustrate bees. They're very hard workers.
FLATOW: Can you tell when they get angry, so to speak?
SUTTON: They will try to sting you.
SUTTON: They do get erratic if you frustrate them, and you have to be careful.
FLATOW: Yeah. I saw that John Ascher was kind of smiling when I said that.
SUTTON: He probably knows it well.
FLATOW: Let me ask both Julie and Gregory: Are both these studies teaching us new things about the behavior of the flowers, also?
MUSTARD: Yes. I would say definitely, because in our whole - what we come away with from this study is that the plants are manipulating the pollinators. So, in some sense, they're in charge in this situation, because they're the ones putting in the caffeine and manipulating the behavior of the pollinators. And the only reason we have those lovely flowers - and the flowers have nectar - is basically so pollinators will come and then take that pollen to a plant of the same species somewhere else.
So I would say, absolutely, we're really learning that the plants - that this interaction the plants are not just being passive, but they play an important role in how pollination takes place.
FLATOW: I'm sorry. Let me just give out a little number. 1-800-989-8255 is our number. This is SCIENCE FRIDAY, from NPR. I'm sorry, Gregory. Did you want to jump in there?
SUTTON: Yes, yes. I'd like to add a point that when Julia mentions that it's an active process on the part of the flowers, we actually found that we were measuring electrical activity in the plant. And before the bee reaches the flower, there's a spike of electrical activity in the plant...
SUTTON: ...that lasts for about 100 seconds. And we think that the plants aren't just being - aren't just displaying nectar and pollen, aren't just using sight, but are - might be manipulating this electric field in order to have a real-time interaction with the bee.
FLATOW: Wow. Wow.
SUTTON: And we have a fantastic number of hypotheses of what the plant could be doing with this very fast thing that the bee will be able to perceive.
FLATOW: There must be some interaction going on there...
FLATOW: ...between them, you would suspect, right?
FLATOW: Yeah. Let's go to the phones. Katie in Buffalo. Hi, Katie.
KATIE: Hi. I'm calling because I actually have a phobia of bees. And when I heard about this electric charge, I'm wondering if that might be a nice, natural way to deter bees, to have some sort of electric charge around the house or around that that might, you know, discourage them from coming near me.
FLATOW: Well, let me - that's a good question. Let me get two - let me attack it from two different ways. First, let me ask John Ascher: If you don't like bees, how can you get them to stay away from you? Should you not swat at them? Is that the worst thing that you're going to be doing?
ASCHER: Well, the first thing I want to make clear is that most of the bad press that attends to bees should be really directed elsewhere. So...
FLATOW: To whom, then?
ASCHER: Well, some of the stinging wasps are much more aggressive than honeybees. And of the bees, the non-native honeybee is by far the most dangerous one. Our native bees are, almost without exception, pose no danger whatsoever to anybody, to the public. If they do sting, the sting is very mild and not particularly dangerous. The honeybee can be very dangerous to people, especially if they're allergic. But a lot of the fear of bees in general is overblown.
Male bees of all species can't sting at all. And many of our most common native bees can't sting people whatsoever. You can safely hold them in your hands. So I find a lot of the fear of bees to be exaggerated.
FLATOW: Well, let's ask about the electric - Gregory, what about the electrical properties? Can you wire yourself or something?
SUTTON: Well, we know they can detect electric fields, but we don't know yet if they've got preference for them. It'd be absolutely lovely to put a small, positive electric field around and have the bees avoid it. But we don't - we know they can learn about electric fields, but we haven't figured out what their preferences are yet.
FLATOW: Well, can you do that experiment? Can you do that experiment?
SUTTON: Yeah. Well, we're working on those experiments now. We were surprised they could detect them at all.
FLATOW: How close do they have to be to the flower to detect...
SUTTON: It's on the order of centimeters, a few inches, not much farther than that. But we don't have exactly how far it takes, how far - how close they can get yet.
FLATOW: Wow. So there's a lot of work still to be done.
SUTTON: There's a huge amount of work still to be done.
FLATOW: All right. We're going to take a short break. When we come back, we'll talk lots more about bees. Our number: 1-800-989-8255. Opening the phones to get other questions. And also, if you want to talk about the electrical properties or bees and caffeine, and you're in the middle of lunch, it's a good time to take the time to do that. You can also tweet us @scifri, @S-C-I-F-R-I. You can go to our website at sciencefriday.com or our Facebook page, scifri, and leave some questions and comments there. So don't go away. We'll be right back after this break.
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FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY, from NPR.
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FLATOW: This is SCIENCE FRIDAY. I'm Ira Flatow. We're talking this hour about bees, all kinds of bees, everything about them, and some interesting new research about their caffeine habits, so to speak, and their properties of electrical fields interacting - flowers' electric fields interact with bees. My guests are John Ascher, who is from the American Museum of Natural History, Julie Mustard of Arizona State University, Gregory Sutton at the University of Bristol.
Gregory, we have a tweet came in, that is very interesting and obvious question which we didn't really answer, which is: What is the mechanism? How does a flower create an electric field, anyway? That's from the Edmond Wine Shop(ph). What do you say that?
SUTTON: Well, OK, the - if I were to create the electric field, at the most simplest level, it's not creating an electric field. It's manipulating an existing electric field. There is an electric field of about 100 volts per meter just in the atmosphere at - on a sunny day. On a clear day, it's about 100 volts per meter. And a plant is basically a ball of fluid stuck into the ground. So the shape of the plant manipulates that electric field.
FLATOW: So why doesn't the electric field have a current that shorts out through the plant and zaps the flower or the plant as it gets grounded?
SUTTON: Well, there's - it's a - there's a very small amount of charge going through, and it's for the same reason that there isn't a current going through a building. The resistance through the air is too high. And the resistance to air is very resistant to current. So it's the resistance of the air that's preventing current from flowing to the plant at all times.
FLATOW: Are there any other animals or insects that can detect and respond to these electric fields?
SUTTON: Oh, yes, yes, yes. The most famous is electric fish, of course, that can generate electric fields and can communicate with one another using electric fields. And sharks have electric field detectors on them that they use to detect prey. The platypus can detect electric fields on its nose - well, its bill - and, of course, eels, as well, electric eels.
FLATOW: So let's go to the phones. Janet in northeast Florida. Hi. Welcome to SCIENCE FRIDAY.
JANET: So fascinating.
FLATOW: Thank you.
JANET: This is so fascinating. So I'm an urban farmer, and I have to grow very intensive vegetables, you know, production. So I'm really interested in bees. I've been told that bumblebees are too fat to get down into most flowers, so they're not good pollinators. And my second question is: I attended a program the other day where an animal rights attorney basically explained that vegans, you know, don't - I mean, it's basically because plants aren't sentient, it's OK to eat them. I'm really having a problem with that.
JANET: If you're smart enough to make caffeine and electrical fields, you're pretty darn smart.
FLATOW: You think that vegans are having a problem with plants now because they can do all these things?
JANET: I don't think they are as of the moment that your program started, but...
JANET: I mean, seriously, it's like a pep talk every Friday. I love it.
FLATOW: Well, thank you very much. Greg - let me ask you, John: Are honeybees better pollinators than bumblebees? She has a farm. She wants to get the most out of her productivity out of her bees. What kind of bees should she use, right, Janet? What are the best bees for her?
ASCHER: OK. I think she mentioned that she was in northern Florida. Is that correct?
ASCHER: Anyway, I have a colleague, Glenn Hall at the University of Florida. We've done some major surveys of bees in that region, including gardens in Alachua County, near Gainesville. And we found a big array of native pollinators. And so these are small-scale farms, and we find a big diversity of native bees of all sizes, tiny sweat bees, all the way up to big bumblebees. And depending on the plant, one of the other of these size classes would be a better pollinator. The whole array of species are really necessary to pollinate all of the crops sufficiently. I can say that honeybees are better for big monocultures.
ASCHER: And if you have a small, diverse farm, then you're going to have a whole array of native bees helping you.
FLATOW: So you're saying the native bees will find the plants themselves. You don't have to worry about which bee goes to what plant.
ASCHER: Well, that was a key part of our studies there in north Florida, was to see how the bees in the natural areas pertain to the bees in the farms. And so what we found is sometimes the farms actually had more numerous bees than some of the natural areas. But at the same time, it's critical to maintain the natural areas...
ASCHER: ...so that you maintain the species diversity and the nest site for the native bees. So you really need both.
FLATOW: Jen, does that answer your question?
JEN: Yeah. I actually do a lot of trap cropping and, you know, integrated pest management. So I plant things that would also be attractants to bees, like buckwheat and such like that. So the guy's name is Glenn Hall in Alachua at University of Florida?
ASCHER: That's right. Yeah.
JEN: Awesome. Thank you so much.
FLATOW: Thank you. Happy spring.
JEN: Yeah. I love it.
FLATOW: 1-800-989-8255. What don't we - let me - let's go - all three of you, what still mysteries remain about bees that we would - we need them, we'd like to find out. John, you have any?
ASCHER: Well, I think the life history of most of the species - meaning where they nest, which plants they visit - remains unknown. So out of those 20,000 species I mentioned, there's only maybe a few hundred at most for which we have even a basic understanding of their life history. And so it's really critical to learn just the basic facts about where these bees live and what they do. Clearly, they're doing amazing things: sensing electric fields and remembering flowers and so forth. But we really lack the most basic information. So I think we need more information about bees.
We also need more - a better understanding of status of bees and how they're increasing or decreasing in abundance in response to global change. And one of the keys to that is to capture historical specimens from many, many different collections and collaboration, and then to have, statistically, colleges contending with these data in a very sophisticated way. And in this way, we can inform policymakers and really have a good idea about conservation of threatened bees, and also how - we need to more in order to inform decisions about large-scale pollination.
FLATOW: Here's an interesting tweet from Connor Jennings, who's wrapped the whole thing up in one, neat ball. And he says: Does caffeine help the bees detect electric fields more effectively?
SUTTON: Great question.
MUSTARD: Well, we could certainly get - work together on answering that question, I guess. But they really...
SUTTON: I'd be fantastically interested.
MUSTARD: Yeah. They remember - I mean, caffeine is helping them - we specifically looked at their ability to remember odor, but bees also use cues like color, as well as, I guess, electrical fields. So I would expect that the memory would be helped, just in general. But it would be very, very fun to do some of those studies.
FLATOW: I understand that you've also done some studies on the effect of alcohol on bees.
MUSTARD: Yes, indeed. We're really interested. So what I really have been interested in is how - what are the pathways in the brain that allow us to remember and learn about things? And the compounds that cause addiction - actually, the latest theories is that that's actually kind of learning. And so things that are addicting are actually affecting the same pathways that you normally use for learning about positive stimuli. And so we started out looking at the effects of alcohol. And it's very interesting, especially listening to the fellow who was on before us talking about the effects of wine. And we've definitely shown with honeybees that alcohol also affects learning. So you can't remember new things, but if you're - if you've actually already learned something and you're trying to remember it when you've been drinking, you can remember stuff you've already learned.
FLATOW: What does a drunk bee do? How do you...
MUSTARD: Well, it depends on how drunk it is. So it's like, you know, going to a party on a college campus - I won't say which one. And you basically go to the party, and at the beginning of the party, people start drinking. And first thing they do is they get really excited. They jump up and down more. They start dancing. And by the end of the party, they have consumed even more alcohol, and a lot of them are kind of laying passed out on the floor. And bees basically have the same kind of response. Low doses basically make them enthusiastic, and really high doses basically make them lay on their backs, waving their legs in the air, and they can't right themselves.
FLATOW: No kidding.
MUSTARD: Yeah. So it's very cool.
FLATOW: How do you get a bee drunk? I mean, that doesn't normally drink alcohol, does it?
MUSTARD: Well, no, it doesn't normally drink. But if you've ever been sitting outside with your - well, OK. I'm in Arizona, so maybe this happens more here. But if you're sitting outside with your daiquiri or your margarita, you will know bees will come by and will be happy to consume alcohol. So we didn't have to force the bees to drink the alcohol. They were quite happy if we mixed it in a sugar solution, that they were quite happy to drink it on their own.
FLATOW: What does a bee hangover feel like? I wonder.
MUSTARD: Well, we haven't asked the bees that question yet, but in other invertebrate model systems like drosophila and nematodes, C. elegans, they actually do seem to have negative effects from having drunk alcohol and then not having it. So it's quite possible they do actually have hangovers.
FLATOW: Let me see if I get a - that's quite interesting. We got Benjamin in Massachusetts. Hi, there.
BENJAMIN: Hi. I'm a beekeeper in Massachusetts, actually at Olin College of Engineering. And I have a question about the caffeine.
BENJAMIN: So I understand that when bees collect nectar, it, of course, has a very low concentration of sugar, and it must have a low concentration of caffeine. Yet we don't see caffeine in a honey when they concentrate the sugar. Does it (unintelligible) to concentrate the caffeine, or do they digest the caffeine, and we're only left with the sugar.
FLATOW: Good question.
MUSTARD: So, actually, if you look for caffeine in honey, especially honeys that are produced from bees that are mainly foraging on coffee flowers or citrus flowers, there is a pretty high concentration of caffeine in the honey, as well. So - but...
FLATOW: Does is get processed out when they - if you...
FLATOW: Yeah. If you eat raw honey, will you get more caffeine?
MUSTARD: Yes. So - I mean, the thing is that bees really want to be generalists. They like to go out - and different bees like to go out and go to different flowers. So the honey that you get from the bee colony is a mixture of nectar from lots of different types of flowers, normally. And only a few flowers actually seem to have caffeine in them. And so that way, when it's all mixed together, you don't see as much of the caffeine, but it's definitely there. And in citrus honey, it can be actually quite a high level of caffeine in the honey itself.
FLATOW: Start putting that percentage on the jars.
FLATOW: People will start shopping - we've run out of time. This is quite fascinating. It's our annual spring bee fest. I want to thank all of you for taking time to be with us today. Julie Mustard, assistant - research professor in the School of Life Sciences at Arizona State, John Ascher, research scientist specializing in invertebrate zoology at the American Museum of Natural History here in New York, Gregory Sutton, postdoctoral research assistant at the University of Bristol. Once again, thanks - thank you all for joining us today.
MUSTARD: Thank you.
ASCHER: Thank you.
SUTTON: You're welcome.
FLATOW: You're welcome. I'm Ira Flatow. This is SCIENCE FRIDAY, from NPR. Transcript provided by NPR, Copyright NPR.