After a winter that many beekeepers have described as particularly hard on their hives, Eric Mussen, extension apiculturist at the University of California, discusses the plight of the modern honeybee and the threats the tiny pollinators face from disease and pesticides.
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IRA FLATOW, HOST:
If you're in some of the more temperate parts of the country, spring is when you get to head outside after being cooped up indoors for much of the winter. You head out of the hive, you spread your wings, look for a source of nectar. Oh wait, wait, that's the bees.
But in many parts of the country, beekeepers are reporting that they've had a very rough winter, one of the roughest winters on record, with many cases of dead bees in the hives or total colony collapse. Joining me now to talk about the tough times honeybees are facing in the East is Eric Mussen. He's extension apiculturist for - apiculturist at the University of California system, based in the Department of Entomology at U.C. Davis. Welcome to SCIENCE FRIDAY.
ERIC MUSSEN: Thank you very much for the invitation.
FLATOW: You're welcome. It's really been a bad winter for bees?
MUSSEN: Yes, and it wasn't just in the East, either. I mean, it's happening all over the country, whatever this phenomenon is. Weather was involved more last season than some years, but there's some underlying problem here that we just don't recognize.
FLATOW: Could it be many problems coming together?
MUSSEN: Well I think yes, it's a compilation of a bunch of stresses that are all hitting our hives at one time or in the colonies. The bees just can't handle it, and they kind of throw in the towel.
FLATOW: Such as? Give me an idea of the stresses you're talking about.
MUSSEN: Well, one is basically nutrition. Honeybees are just like you and I. They need a mix of pollens in order to get all the nutrients that they need so that they can feed their brood and keep it healthy, so that they can produce the food that's fed to the queen so she can lay 1,000 to 2,000 eggs a day.
It keeps your immune system up. It keeps your detoxification systems up in case you run into chemicals, that sort of thing. So that's primary. And what we're finding out now is that the old places where the beekeepers used to go to kind of give their bees some R and R and to get a honey crop if they were lucky are planted with corn, corn, corn, corn all over the place now.
So that's one of the things, we're short on bee food to begin with. And then the second thing is that most of the colonies have a parasitic mite called varroa in them, and if that mite feeds on a bee, it extracts some of the bee blood, and therefore the nutrient levels become lower, and you get a shortened life expectancy.
And it also reduces the immune system of the bee to the point that it isn't so good at fending off other diseases and whatnot. And then we've got a relatively new parasite that it's a fungus-like thing that lives in the intestinal tract of the bees, and I think we've got 23 RNA viruses now that we know that can be a problem in the bees, and the good old varroa mite can vector practically all of those.
And now finally you come to the one that the beekeepers are most concerned and generally the general public is, as well, and that's exposure to pesticides. And we've got two routes of exposure. One is in order to keep those varroa mites under control, the beekeepers put different materials into the hives, right in with the bees, to try to suppress one arthropod living with another arthropod. That's kind of tricky.
FLATOW: Well hang on to that...
MUSSEN: So those are the stresses.
FLATOW: I want to talk about other pesticides that are out there, some of them that are of even more concern. We'll come back, we're going to talk lots more with Eric Mussen about bees. Our number, 1-800-9898-255 if you'd like to talk about the bees that have died off this winter. We'll be right back after this break. I'm Ira Flatow. This is SCIENCE FRIDAY from NPR.
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FLATOW: I'm Ira Flatow. We're talking about bees with Eric Mussen. He's extension apiculturist for the University of California system in U.C. Davis. We were talking - we're talking about the bee die-off this winter, and the last thing you mentioned, Dr. Mussen, was the problems with pesticides, and there has been a lot of talk in the past week or so about pesticides called neonicotinoids. Are they a particular threat to the bees?
MUSSEN: Well, they're relatively recent, and they don't affect the bees in quite the same way that the insecticides of old used to bother us. What used to happen was that an application was made, and a lot of bees could be lost, but it was parts per million that was killing the bees.
And then it was relatively short-term. I mean, if it didn't beat the daylights out of your bees too badly and kill them off or something, they recovered fairly soon. But we had hardly any of those older chemicals that were systemic, which means they go into the plant.
And these neonicotinoids are extremely good at going systemically into the plants. So they're in the roots, the stems, the leaves, and if they happen to flower, they're in the flowers, and that means that they're likely to show up in the nectar and the pollen. And the bees are out there collecting it in field crop situations and whatnot.
The amount coming back is generally somewhere between four and 10 parts per billion, not million. It's 1,000 times less than what we used to worry about. And yet even at those very, very small amounts, if you put bees in a cage and treat them in the laboratory, you can prove that those materials affect their nervous system, their brains. Their behavior changes, and they're a very different bee, there's no doubt about it.
But the studies that have been published so far out in the field, where you put these very low, very sub-lethal doses into their food in the field, it seems to be diluted, and you don't notice these affects that you notice when you have them in the cage in the lab.
FLATOW: Could they be bringing them back - are they longer-lasting pesticides?
Oh yeah - excuse me. They're persistent both in the environment, and actually I've seen a lot of analyses now, because we're working on CCD so much, of the chemistry coming back from the beeswax in the hive and the stored pollen in the hive and the bees themselves in the hive.
MUSSEN: And the neonicotinoids don't show up very often. They're not very frequent, and when they are, their levels are very, very, very low compared to a lot of other things that we're finding in there. But that does not necessarily mean that they're not a problem. But nobody's really been able to show that they're any more problematic than the rest. The only thing we know is that, you know, the bees will be exposed, every single day that the crop is in bloom, and that's not the way it normally used to be.
We used to get one big exposure, and it was over. And now this is exposure, you know, throughout the bloom. So they're getting these sub-lethal levels, you know, a lot of the time, but the question becomes one of we can't do it yet, and it looks like parts per billion wouldn't be problem. But could parts per trillion, another thousand times smaller, actually be a problem?
And unless we can resolve that - or synergism. And that's where when you have an effect A and an effect B from two different chemicals alone, when you add them together it's A plus B plus wow, it got much, much, much greater. And so you have two things that would barely hurt the bees at all, put them together, and they just knock the socks off the bees. That's synergism.
And when you have - we found I think it's somewhere close to now 150 different residues if you've been looking at what we found in bees and wax and pollen and whatnot, and if you begin to see all the potential combinations that there could be there now, and they could synergize each other, it's just a soup of materials that the bees are living in, and I guess we could be a little bit surprised they're doing as well as they are.
FLATOW: Wow, what an assault on the bees.
FLATOW: Wow. Let's go to Kathleen(ph) in Phoenix. Hi Kathleen, welcome to SCIENCE FRIDAY.
KATHLEEN: Thank you, how are you?
FLATOW: Fine, how are you?
KATHLEEN: Fine, thank you. My husband and I were just commenting to each other that we think we have more bees than we've had in our backyard for a very long time, and I was wondering if there is anything that the regular gardener can do to help increase the bee population.
MUSSEN: I think there are two things that the regular gardener can do. First of all, if there's a time of the year when wildflowers are not available for the bees to feed on, and out here in California it's dry all summer, so by the end of summer and early fall, our bees are really lacking for food. If somebody can plant plants that will bloom at that time of the year, it can provide some of these extra pollens that they need in their diet to make them healthy.
And then the second thing that any gardener can do is to pay strict attention to the labels of the product that they're using and try not to put any kind of an insecticide, herbicide and whatever, on the plants while they're in bloom and they may contaminate the pollen that the bees are bringing back to the hive. Because if we keep our pollen clean, I think our bees will be a lot better off.
FLATOW: OK, Kathleen?
KATHLEEN: Thank you so much. Thanks a lot.
FLATOW: Thank you for - you're welcome. 1-800-989-8255. We've always heard about bees as a major commercial pollinator for crops like almond trees. If you put a hive down in the middle of an almond crop, are they only getting nutrition from the almonds, and is that a problem?
MUSSEN: Well, it appears as though yes, when they're in the almonds. Basically almond pollen and nectar are just practically about everything that they're bringing in. But it can't be too problematic because they've got some stored pollen. And this year, the stronger colonies that were brought into almonds actually built up so well that they could put a - what we call a super nectar box in the box and make almond, which isn't particularly good to eat, and we're going to have some on our picnic day honey day just to show people what almond honey is like. It's not too good.
FLATOW: I heard it tastes like sweaty gym socks. Is that right?
MUSSEN: I don't know. I'll have to try it and find out.
MUSSEN: But anyway, but the bees that came in weak in the first place, particularly if a spray went on during bloom, oh man, they came out really crippled. So, you know, it kind of depended on where you were and what happened in your orchard, et cetera, et cetera.
FLATOW: Does anybody know nationally how many bees we lost or what percentage of bees are gone?
MUSSEN: I think that number will be generated shortly by a group in the U.S. called the Apiary Inspectors of America. And each state, or practically all the states, has a state apiarist in the Department of Agriculture, and they survey their beekeepers, and then they lump all that information together, and they put out a report, and it normally comes out in the latter part of April or May at the latest. So we're going to see it pretty soon.
But anyway - yeah, I could guess.
FLATOW: You can guess?
MUSSEN: Yeah, I can guess. It's going to be worse. I think we're probably going to have the worst losses we've seen so far this past winter.
FLATOW: And that would put a number at what?
MUSSEN: Well, I don't know for sure because we had a couple of times in the past reached 35 percent loss, 33 percent loss.
MUSSEN: But then we had some 29 percent, and last year was 26 percent. We thought things were going a little bit better. But I wouldn't be surprised if we surpassed that 35 percent.
FLATOW: How long can you lose almost a third to a half of your bee population and still have something viable?
MUSSEN: Well, there's two parts to the answer to that question. About 75 percent of our beekeepers in the U.S. don't have those losses. They used to lose five to 10 percent. Then we got a couple of used-to-be-exotic mites that moved into our bees, and then their level of losses was closer to 15 to 20 percent. You can survive that economically by splitting your strongest colonies the next year and starting up so you get your numbers up.
But the other 25 percent of the beekeepers are the ones who are really vexed by these losses, and those individuals will lose 40 percent, 60 percent, 80 percent. Well heavens, economically I don't know how many years they can stay in business like that because, you know, it just makes sense. They're not going to be able to persist.
FLATOW: Not to mention the bees themselves, losing the bees. Yeah, thank you very much, this is quite interesting. Thank you very much for taking time to be with us today.
MUSSEN: OK, thank you for inviting me.
FLATOW: You're welcome. Eric Mussen, extension apiculturist at the University of California system, based out there at U.C. Davis Transcript provided by NPR, Copyright NPR.