Neonicotinoids are Killing Our Insects (and Then Birds) Dead

by on December 17, 2010

Earlier this week, I posted about the growing concern that Colony Collapse Disorder may be driven in part by bees’ exposure to clothianidin.

Clothianidin is part of a class of systemic pesticides known as neonicotinoids, and they have been used widely across U.S. agriculture since the early to mid-1990s. “Systemic” refers to the fact that the pesticide pervades the plant it’s applied to entirely, and so any troublesome insect that takes a bite of any part, from root to leaf, will be poisoned.

When bees began dying off in large numbers in Europe, the precautionary principle was employed and neonicotinoid use was restricted or banned. (With interesting bee-bounceback results.) In the U.S., where the EPA professes to have no conclusive reason to act, beekeepers have been left to enforce their own boycott.

A SunBreak reader alerted me to the work of Dutch toxicologist Henk Tennekes (not the climate change impact skeptic), and his research that concludes honey bees and birds can scarcely help being affected by neonicotinoids. “Improper” use of a pesticide is one thing, but his 72-page, heavily footnoted scientific treatise, A Disaster in the Making, demonstrates that this class of pesticides is unsafe in any hands.

“It is a serious ecological report rather than a book for general readers,” warns the website, but a serious ecological report is exactly what is required. Tennekes explains in this podcast that neonicotinoids are persistent in the environment in two ways: first, they can be active for months in plants they’re applied to, but more importantly, their neurological effects (a dérangement de tout les bee sens) may be irreversible.

Neonicotinoid insecticides act by causing virtually irreversible blockage of postsynaptic nicotinergic acetylcholine receptors (nAChRs) in the central nervous system of insects. The damage is cumulative, and with every exposure more receptors are blocked. In fact, there may not be a safe level of exposure.

That specific effect is what makes beekeepers nervous, because Colony Collapse Disorder (unlike other bee epidemics) doesn’t leave you with a hive full of dead bees; it leaves you with an empty hive. The disorientation that these pesticides provoke seems like a smoking gun, when also tied to a lack of grooming that would allow mites and funguses to flourish. Tennekes notes that if initial contact is not enough to kill (though it often is), the effects will accrete until the insect or earthworm bites the dust.

That dust is also compromised. Writes Tennekes: “The second catastrophic disadvantage of neonicotinoids is their potential to leach from soils. [...] The excessive imidacloprid levels noted in surface water of western Dutch provinces with intensive agriculture have already been associated with insect decline and a dramatic decline of common grassland birds.” Birds, you’ll recall, feed on insects. If swaths of seemingly productive farmland are in fact food deserts, it’s Rachel Carson’s Silent Spring revisited, says Hennekes. (And U.S. bird population would not seem to be immune.)

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