Is genetically modified corn a honeybee killer?

A German beekeeper sounds the alarm: Sick bees don't fare well on an intensive diet of poison.

Published March 28, 2007 4:49PM (EDT)

A new plot twist in the mysterious case of the disappearing honeybees. Several readers responded to Monday's post on the popularity of Monsanto's triple-stack hybrid GM corn by pointing me to a Der Spiegel article speculating that the spread of genetically modified crops might explain why bees are dying in unprecedented numbers.

The problem is not confined to the United States. Bees are also dying in Germany. And according to a German beekeeping official, Walter Haefeker, the cause could be GM corn containing built-in pesticide. Haefeker has been pushing a study conducted by German researchers at the University of Jena between 2001 and 2004.

Der Spiegel:

The researchers examined the effects of pollen from a genetically modified maize variant called "Bt corn" on bees. A gene from a soil bacterium had been inserted into the corn that enabled the plant to produce an agent that is toxic to insect pests. The study concluded that there was no evidence of a "toxic effect of Bt corn on healthy honeybee populations." But when, by sheer chance, the bees used in the experiments were infested with a parasite, something eerie happened. According to the Jena study, a "significantly stronger decline in the number of bees" occurred among the insects that had been fed a highly concentrated Bt poison feed.

According to Hans-Hinrich Kaatz, a professor at the University of Halle in eastern Germany and the director of the study, the bacterial toxin in the genetically modified corn may have "altered the surface of the bee's intestines, sufficiently weakening the bees to allow the parasites to gain entry -- or perhaps it was the other way around. We don't know."

Of course, the concentration of the toxin was ten times higher in the experiments than in normal Bt corn pollen. In addition, the bee feed was administered over a relatively lengthy six-week period.

Detailed information about the results of the study can be found here. But before citing this data as the smoking gun that wraps everything up neatly, let's consider a few caveats. First, as Der Spiegel notes, GM corn constitutes only .06 percent of all corn planted in Germany. The comparable figure for the U.S. is 40 percent. The fact that bees are dying in both countries, but there is such a great disparity in the deployment of Bt corn, actually weakens the case that Bt corn is the culprit.

Second, it doesn't seem that surprising that feeding a super-intensive diet of pesticide to bees that were already sick caused them to die en masse.

The real mystery here, in my mind, is not whether Bt corn can be conclusively proven to be a genocidal bee murderer. I don't think anyone can say that at this point, although I have no doubt that some GM critics will promote the Jena study as definitive. What I'm wondering is why the New York Times' Alexei Barrionuevo, who wrote a lengthy article on the disappearing honeybees on Feb. 27, did not mention the possibility that GM crops might be a suspect. Barrioneuvo wrote only that "Investigators are exploring a range of theories, including viruses, a fungus and poor bee nutrition." Meanwhile, in Germany, Haefeker has been touting the results of the Jena study since as far back as 2005.

As a data point to be added to the mix, the Jena study is provocative, and illustrates an important point. A laboratory study that isolates one factor -- Bt corn pollen's effect on bee health -- doesn't tell us what will happen when Bt corn pollen is combined with something else, like a mite infestation, or a bee virus. The complexity of such interactions is vast, and is one primary reason to be skeptical of all blanket assurances from industrial representatives declaring, with arrogant certainty, that something is "safe."

UPDATE: Somehow, I missed that the San Francisco Chronicle had explored this very question on March 10, in an article titled "Could genetically modified crops be killing honeybees?"

By Andrew Leonard

Andrew Leonard is a staff writer at Salon. On Twitter, @koxinga21.

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