Saturday, May 05, 2007

The Buzz on Insecticides, Insight into the Problem Facing American Beekeepers

Einstein once remarked that if bees disappear, humans will only have a few years to survive. Well, we may be in trouble. Two weeks ago the New York Times ran a piece in Science Tuesday reporting on the demise of U.S. bee populations. More than a quarter of the country's bee population has died, although in parts of the country numbers are as high as 70%. The bees are suffering from "colony collapse disorder". The name was probably chosen because nobody knows anything about the disorder, except that it causes colonies to collapse. While the cause of the bee collapse is unknown, theories abound, including poor nutrition, insecticides, viruses, diarrhea, dead queens and the list goes on.

Autopsies reveal that bees from collapsing hives are immuno-compromised, which bolsters the virus theory. My favorite theory, however, is that bees are being killed by insecticides applied to the crops they pollinate. Luckily, the NYT ranks my favorite theory among the three most likely, so I don't think I'm seeing too many black helicopters.

Insecticides on the short list of suspects are fipronil and imidacloprid, both from a class of compounds called neonicotinoids. These insecticides can be applied to the soil directly or used as a seed coating. They are attractive to farmers because they provide gradual release throughout the plant's maturation. Theoretically, the chemicals are gone by the time the plant flowers. In practice this is not happening. Furthermore, French research has shown that fipronil persists in the environment and traces of the compound have been found in the air and the food chain. Manufacturers maintain that the chemicals are safe.

This recent bee scare is not the first time neonicotinoids have come under fire. The French Minister of Agriculture banned imidacloprid in 1999 and fipronil in 2004, at least for use on sunflowers and corn. French newspaper Le Monde reported that the ag minister formally charged the manufacturers with "sale of a toxic product harmful to humans and animals" and "complicity in destruction of livestock". French government made this decision in response to pressure from beekeepers who blamed the insecticides for bee declines similar to those in the U.S. Bee populations in France have not bounced back following the ban, although the national Union of French Beekeepers reported improvements in 2005. Even if the populations haven't rebounded, it would be difficult to rule these chemicals out because they persist in the environment and were only banned for use on two crops.

Fipronil manufacturer, Bayer CropScience has seen the inside of a U.S. courtroom over similar claims. Although the case settled, Louisiana crawfish farmers brought a class action against Bayer claiming that fipronil killed their crawfish. (Fipronil was used as an insecticide in rice paddies, which double as crawfish ponds.) Bayer paid the crawfishermen $45 million in settlements.

Researchers are still considering insecticide poisoning as a cause of the current bee demise. Bees from affected hives are being screened for 117 different chemicals in order to see if compounds such as neonicotinoids could be to blame.

It will be interesting to see how the U.S. lawmakers and regulators respond to this scare, especially if scientists cannot pinpoint a cause for collapsed colony disorder. When Tyrone Hayes exposed the endocrine-disrupting effects of a popular herbicide, atrazine, U.S. lawmakers did not take a precautionary route. The EPA did not revise the Safe Drinking Water Act's 3 ppb threshold for atrazine, despite the fact that lower levels of exposure caused male frogs to become hermaphroditic. Atrazine, however, is different than fipronil or imidocloprid because it threatened aquatic ecosystems and human health, not crops. Public health and environmental health are both public goods that do not inspire the lobbying zeal of big agriculture. Because so many crops depend on honeybees for pollination, powerful lobbyists might be on the side of precaution this go round. We'll see though, I still wouldn't bet on it.


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