Dead bee.Photo: Maury McCownAs I reported in January, the USDA’s top bee researcher, Jeffrey Pettis, has publicly revealed that he has completed research showing that Bayer’s blockbuster neonicotinoid pesticides, used on million of acres of crops across the country, harm honeybees even at extremely low doses.

The revelation was significant because a growing number of U.S. beekeepers are worried that Bayer’s pesticides might be the key culprit in colony collapse disorder — the strange annual die-off of significant portions of the U.S. honeybee population. In December, a leaked document showed that EPA scientists had declared insufficient a previously accepted Bayer-funded study purporting to show that neonicotinoids don’t harm honeybees in farmfields.

News of Pettis’ as-yet-unpublished study has generated very little press in the United States beyond my coverage. In the United Kingdom, though, it’s made quite a splash — so much so that the USDA scientist got an invitation to address Parliament on the question of pesticides and bees. Pettis addressed Parliament on Monday, and the results were … odd. He distanced himself from calls to ban neonicotinoids. In an account of his testimony before Parliament, The Guardian quotes Pettis like this: “Pesticide is an issue but it is not the driving issue.”

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On the other hand, though, he pointed to yet more evidence linking poor bee health to pesticides. According to The Guardian, in his testimony before Parliament, Pettis discussed a new phenomenon being observed by beekeepers: Bees are “entombing” or sealing off some pollen-filled cells in a hive. And when scientists test the sealed cells, they turn out to contain significantly higher levels of pesticides and other toxins than unblocked cells in the same hive.

Here’s how Pettis described the phenomenon, according to The Guardian‘s account:

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This is a novel finding, and very striking. The implication is that the bees are sensing [pesticides] and actually sealing it off. They are recognizing that something is wrong with the pollen and encapsulating it … Bees would not normally seal off pollen.

And this novel strategy for dealing with pesticides is evidently not working, as The Guardian reports:

But the bees’ last-ditch efforts to save themselves appear to be unsuccessful — the entombing behaviour is found in many hives that subsequently die off, according to Pettis. “The presence of entombing is the biggest single predictor of colony loss. It’s a defence mechanism that has failed.” These colonies were likely to already be in trouble, and their death could be attributed to a mix of factors in addition to pesticides, he added.

This bit of testimony shines a harsh spotlight on pesticides among the “mix of factors” that appears to be killing honeybees. If the entombing phenomenon is “the biggest single predictor of colony loss,” then the presence of pesticides, if that is indeed what’s driving bees to entomb cells, appears to be the factor that tips troubled hives into collapse.

According to The Independent’s account of Pettis’s testimony, the scientist stressed what he called the “3-P principle — poor nutrition, pesticides, and pathogens.” (By pathogens, he’s referring to the Nosema fungus and a virus called Iridoviridae, both of which appear to be present in collapsed hives.) Pettis bluntly stated that interaction between the three factors is what drives colony collapse disorder, The Independent reports. “It’s the interaction of these three [that matters],” Pettis told Parliament. “You get three of them lined up and surely you’ll have bees in poor health. Even the combination of any two could be problematic.”

Now, to me, Pettis’ testimony is a ringing endorsement for a ban on neonicotinoids. Think about his three factors. “Poor nutrition” stems mainly from lack of access to diverse fields consisting of a wide variety of flowering plants — for example, bees don’t eat very well in the vast areas of the country characterized by monocrop industrial-scale agriculture. But U.S. agriculture has been highly industrialized for decades, and hasn’t changed dramatically since the early 2000s, when the U.S. bee population began to experience trouble. (Much as I’d like to see it, I doubt that the honeybee crisis will inspire U.S. regulators to demand the deindustrialization of agriculture.) Also, many commercial beekeepers feed their hives high-fructose corn syrup in the winter months. Again, that probably qualifies as “poor nutrition,” but the practice predates the rise of colony collapse disorder. As for fungal and viral pathogens found in the environment, we can’t ban them; they are a natural phenomenon, and honeybees can’t survive if their immune systems can’t ward them off.

That leaves pesticides. No, we can’t ban all pesticides. But we can ban ones that have been shown, in microscopic doses, to compromise bees’ immune systems, and that are expressed in the pollen of plants grown on tens of millions of acres across the country. Neonicotinoids fit both of those conditions. Pettis’ own research, which he announced will be published in a peer-reviewed journal as soon as next month, found that neonicotinoids can kill bees at doses “below the level of detection.” And virtually the entire U.S. corn crop, which covers about 25 percent of all cropland in the country, is treated with them.

Pettis hedged on the question of banning neonicotinoids before Parliament. Here is The Indendent:

Asked if he thought a precautionary approach — meaning perhaps a ban [of neonicotinoids] — should be taken with some of the new pesticides, he said: “I’m not a regulatory person so I hate to speak to ‘what should be done’. My own view is that pesticides are one of the issues confronting pollinators, but not the driving issue.”

It’s true; Pettis is a scientist, not a regulator. I hope decision-makers at the EPA — the regulators who oversee the pesticide industry — are listening carefully to Pettis’ analysis of pesticides and bee collapse.