Who killed the honeybees?

A round table of experts answer all our pressing questions about the sudden death of the nation's bees. What they have to say has a bigger sting than we ever expected.

By Kevin Berger

Read more: Politics, News

May 29, 2007 | The buzz about the alarming disappearance of bees has been all about people food. Honeybees pollinate one-third of the fruits, nuts and vegetables that end up in our homey kitchen baskets. If the tireless apian workers didn't fly from one flower to the next, depositing pollen grains so that fruit trees can bloom, America could well be asking where its next meal would come from. Last fall, the nation's beekeepers watched in horror as more than a quarter of their 2.4 million colonies collapsed, killing billions of nature's little fertilizers.

But as a Salon round table discussion with bee experts revealed, the mass exodus of bees to the great hive in the sky forebodes a bigger story. The faltering dance between honeybees and trees is symptomatic of industrial disease. As the scientists outlined some of the biological agents behind "colony collapse disorder," and dismissed the ones that are not -- sorry, friends, the Rapture is out -- they sketched a picture of how we are forever altering the planet's delicate web of life.

The scientists constituted a fascinating foursome, each with his own point of view. Jeffery Pettis, research leader of the USDA's honeybee lab, told us the current collapse is one of the worst in history. Eric Mussen, of the Honey Bee Research Facility at the University of California at Davis, maintained that it may only be cyclical. Wayne Esaias, of the NASA Goddard Space Flight Center, an amateur beekeeper, outlined his compelling views about the impact of climate change on bees. And John McDonald, a biologist, beekeeper and gentleman farmer in rural Pennsylvania, reminded us, if at times sardonically, of the poetry in agriculture.

First things first. The Internet, as you know, loves a rumor. Are cellphones killing the bees?

JEFFERY PETTIS: All the explanations that bees became disoriented by cellphone radiation, or this, that and the other thing -- there is zero evidence for any of it. All we know is we lost the worker population and they died away from the hive. What's unusual is they died over a short time period. Are they flying off to nirvana? Who knows where they are? They are just dying away from the hive, which is normal.

ERIC MUSSEN: It's important to look at what's normal. In the summer, bees go through a six-week life cycle: three inside the hive, three outside it as foragers. Then they die of old age. When bees are coming to the end of their life for whatever reason, they just fly off and don't come back. They fly out to die because flying out and dying is what they do. The question is, Why are we seeing bees with such a shortened life cycle? Well, now we're talking about winter bees. As you move into fall, the colony is supposed to be rearing bees that have a long life expectancy -- from about October to March of the next year. The problem is the winter bees aren't making it. Everything just sort of fell apart near the end of this summer and those bees that were supposed to live up to six months didn't come close.

JOHN McDONALD: That cellphone thing is a major source of irritation to me. If it were true, I suspect about 10,000 people at Penn State would be lying on the street dead now. And yet you see them walking around and talking on cellphones. My son explained to me that cellphone radiation puts out a wavelength of about three inches. A honeybee is three-quarters of an inch long and so the bee is going to create virtually no shadow in that wavelength. That's one reason why I look askance at that theory. The other is where I live, in the middle of Appalachia, the bees are disappearing and there are virtually no cellphones.

One scientist has said solving the bees' disappearance is like "CSI" for agriculture. What's the latest word from the lab?

PETTIS: The latest word is we're working on a lot of different samples we've collected throughout the year. We're working under the idea that bees have suffered a one-two punch. The first is a primary stressor -- poor diet, mites, or low-level pesticide exposure. That puts them in a compromised or weak state, and then a secondary pathogen takes over. Because of how quickly the bees are dying, it seems most likely a pathogen would be involved. So we're looking for a secondary pathogen that might be unique or novel.

Are pesticides a major culprit?

MUSSEN: Perhaps 10 percent of commercial bee colonies in any given year are either severely damaged or die on contact with agricultural pesticides. But there's no reason to believe the exposure this year is any different from last year or any other year.

John, you wrote a pretty strong opinion piece that fingered Bt crops, which have been genetically modified to control insect pests. Based on your experiences as a beekeeper, how did you come to that conclusion?

McDONALD: My first collapse started last summer when a powerful colony, in a manner of a week, went downhill. The drone cone sort of cascaded down over the foundation like ice on a mountain. In another hive that was equally strong, the bees ended up lying dead on a mat that extended about six feet. That didn't happen with the other hives, which is indicative of agricultural poisoning. Also, the drones hung around until snowfall, which is unusual, indicating some kind of kind of behavioral dysfunction with the worker bees.

I did a little research and found two studies about the Bt phenomenon. When you look at the action of Bt gene proteins taken up in the gut of insects, including bees, you find an enzyme that gobbles its way through any protein there and affects the insects. And bees are known to forage on cornflowers to get pollen to rear their young brood. I'm not saying Bt is the sole cause of collapse, only that I would like to have it investigated.

Is there any evidence, Jeff or Eric, of Bt crops killing bees?

MUSSEN: When Bt crops were being used in the fields to control lepidopteron insects, or butterflies, there were a significant number of studies run to try to determine whether or not incorporating Bt into the food of the adult bees, or the larvae, would hurt the bees. And the answer was no.

PETTIS: I contributed to a recent study where we directly fed the Bt toxin to whole bee colonies and could demonstrate no effects on them.

MUSSEN: There was a study, and perhaps this is the one John is referring to, that showed the active chemical in these Bt cultures is a protein crystal that develops in organisms. For four years in a row, an institution fed that protein to honeybees at 10 times the amount that they would ever encounter in the field if they were feeding on pollen. In three of the four years, they saw nothing out of the ordinary. In the fourth year, a parasite showed up, and the bees that had been consuming the protein appeared to suffer more. The experiment didn't say the Bt protein gave the bees the "disappearing" disease, or that it killed all of them; it just said the bees that came in contact with the crops appeared to be more negatively affected by the parasite.

Can you tell us about your experiences with colony collapse, Wayne, and your studies to understand wider ecological causes?

WAYNE ESAIAS: Sure. I'm a small beekeeper. I have about 15 colonies and have experienced some loss. I realize there are many symptoms involved. Still, there are one or two I'm puzzled about. I keep records of when my bees collect pollen and nectar in my backyard. I weigh the hive and I have a time series that goes back to 1992. What I've seen over the course of that time is due to local warming: The pollen and nectar flow come almost a month earlier than they did in the 1970s. This is coincident with the urbanization of the D.C.-Baltimore area, causing temperatures to rise.

I'm also using data from NASA satellites to address how global warming or environmental change might be impacting our honeybee populations, and even the spread of the African honeybee. We see plants blooming at different times of the year, and that's why the nectar flows are so much earlier now. I need to underscore that I have no evidence that global warming is a key player in colony collapse disorder. But it might be a contributor, and changes like this might be upping the stress level of our bee populations.

Next page: Is it the weather's fault?