Wednesday, May 30, 2007

Colony Collapse Disorder, an update

It's been a few weeks since I checked in on the bees. If you recall, domesticated bee populations in the U.S. and parts of Europe have been dying off at alarming rates. Bees are rather important for pollination of all kinds of crops, so this bee die-off has major implications for farmers (and for those of us who think that food is delicious). This bee die-off has been called Colony Collapse Disorder. One of the mysteries has been why they fly off from the hive and don't return (rather than dying in the hive).

Salon.com has an interesting round-table discussion with several experts and one beekeeping crank. The interview is actually a pretty good one, and we get some new information here that starts to make the die-off less mysterious (and less over-the-top sensational). Let's start with why the bees are "disappearing":

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.
Ahh, so it's not the rapture, then. What about cellphones?
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.
Not cellphones. How about genetically modified (specifically BT) corn?
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....

....I contributed to a recent study where we directly fed the Bt toxin to whole bee colonies and could demonstrate no effects on them.
Hmmm... not BT corn. (Though the crank raises the possibility that Bt corn is responsible, both scientists point out that there is no credible evidence that suggests this is true, and plenty that suggests it's not true - well done). What's the current best hypothesis for why bees are dying?
I'm probably the strongest advocate in the United States suggesting that malnutrition was the underlying thing that set up our bees to be whacked by everything else researchers are looking at. Honeybees rely on pollen for protein, vitamins, fats and minerals. That's where their major "health food" comes from. If we are having a typical year, and the rains come, there aren't too many places in the United States where the bees cannot find their mix of pollens to meet their dietary needs and get them through a normal life cycle.

The question is, What happens when things don't go like that? Well, you get this blast of hot temperature, which is about the time the flower buds are forming and the pollen grains are beginning to form. What does that do? You get sterile pollen. A beekeeper could look into the hive and say, "I've got all kinds of pollen in there and the bees disappeared." Well, right, you've got pollen grains, but do they have any nutrition in them?

Anything that interferes with the availability of food, or the quality of the food, is going to be detrimental to the bees. They don't have much of an immune system, so the only way that they can resist being infected by a lot of things is when they have their innate resistance up, and the best resistance is when they're best fed. So my feeling is that their nutrition just wasn't what it was supposed to be, and they were susceptible when they should have been resistant. I think something happened at the end of last year in many places in the temperate climate around the world, not just here, and fouled up the bees' food supply. Unless somebody tells me differently, I'm blaming it on the weather.
Well, one major problem with his model is that this will be rather difficult to test experimentally. Was it weather related problems in their food supply? If so, one would predict that Colony Collapse Disorder won't be much of an issue this year (unless we have similar weather patterns). Though it does predict a solution. Artificial food sources in bad weather years can help keep bees healthy.

The other problem is that given that CCD may have a complex cause, it won't get reported in the news, as it doesn't fit the snug "cellphone" or "GM-corn" label. News media are pretty awful at presenting complex ideas.

In this instance, Salon.com chose to have a "balanced" roundtable giving air time to a crank, they did it in a way that people with access to scientific data could correct his errors. All in all, a decent interview.

Digg!

4 comments:

Pierce R. Butler said...

Why should the malnutrition model be so difficult to test? Pollen from an abandoned hive should be fairly easy to collect; analysis of its nutrient content ought to be routine lab work.

The same should apply to the pesticide hypothesis, which is puzzlingly absent from your discussion.

The Factician said...

The malnutrition/weather model can only easily be tested if the same situation occurs again and they follow it more closely. But another prediction that the weather hypothesis makes is that if the weather is more typical this year, the bees will be fine.

It's my understanding that pesticides have been tested for, and not found. The only thing that has been found is that the bee colony boxes can be recolonized if they've been radiation sterilized (suggesting an infectious agent), but can't be if they haven't been sterilized. But the gentleman that raises the weather/nutrition hypothesis brings it up as a one/two punch. Bad nutrition leads to susceptibility to infectious agent.

Pierce R. Butler said...

2nd try at posting this:
Ahh, that does help to fill in the blanks - though my brief dabblings in beekeeping left me with the impression that pollen stored in honeycomb has a long shelf life.

It’s rather startling these days to hear that an economically-critical infectious organism can be deduced in specific locations but is not identified. Does this represent a set of labs stymied by something which eludes the standard tests, or a pitifully inadequate research effort?

The Factician said...

Does this represent a set of labs stymied by something which eludes the standard tests, or a pitifully inadequate research effort?

I honestly can't say, as I'm not directly involved. However, I can say that the amount of money being spent on human disease is woefully inadequate. I imagine that people studying bee diseases are working with paperclips and duct tape.

That said, identifying a disease de novo isn't terribly easy. Once you've used the diagnostic tests for the usual suspects (usually using PCR), you're left with techniques that are very slow. So even with decent resources, it ought to take a while to identify a novel pathogen. Keep in mind, in 2007, it takes over two months to positively diagnose a human being with tuberculosis. I can only imagine bee work is even more challenging.