Disappearance of Bees and the Pesticide Link

by Anne Sherrod

Canada has been suffering unusually high losses of bees each winter since 2006. That's the year when a new and unexplained set of symptoms called colony collapse disorder (CCD) began to be recognized, in which all the worker bees in a colony simply disappeared.

Very high commercial honeybee losses have continued since then, with 30.9% of hives lost in Canada in 2010/11. This doesn't include the serious decline ofwild bees or other pollinators. 

Various infectious organisms, including two species of fungus from the genus Nosema, have received most of the blame; but taken alone they do not account for the symptoms of CCD. Scientists agree that there must be multiple factors involved.

For years there has been strong evidence that one of the culprits may be a family of insecticides called "neonicotinoids" (for their similarity to nicotine). They include the world's number-one selling insecticide, imidacloprid, and its best-known relatives, clothianidin and thiamethoxam – all of which are widely used in agriculture.

From the time they came on the market, starting in 1995, these chemicals were known to be highly toxic to bees. However, only recently has research been throwing light on some of the mechanisms. In 2010 and 2011, researchers in the US and France found that the combination of low doses of neonicotinoids and Nosema infection significantly weakened bees, and caused more deaths than Nosema alone (Alaux, et al, 2010; Vidau, et al., 2011; Pettis, et al., 2011).

In early 2012, researchers from Purdue University investigated bee deaths in Indiana that occurred around corn planting time. The corn seeds were first treated with clothianidin and/or thiamethoxam, then coated with talc to lubricate the seeds' flow through the planting machines. The machines blow large amounts of talc into the air as they plant. The scientists discovered that the insecticides were concentrated in the talc to a level 700,000 times the lethal contact dose for a bee (Krupke, et al., 2012).

Canada's PMRA

Canada's Pest Management Regulatory Agency (PMRA) registers pesticides for use in Canada. Its evaluations are based mostly upon studies provided by the applicants: the agrichemical companies that make millions of dollars from selling the products. Even when the studies are insufficient and the PMRA requires the companies to do more research, the agency may provide "conditional" or "temporary" registrations.

In 2007, there were 33 registrations for imidacloprid products, plus four applications; five years later there are 47 registrations and 24 applications. The brand names include Admire, Genesis, Alias, Grapple, Gaucho, Concept, and Stress Shield. The crops on which they can be used have also expanded to cover a wide range of vegetables, grains, nuts and fruits. Yet there are presently no PMRA evaluation documents environmental impacts of imidacloprid dated later than 2001, when the registrations were said to be "temporary pending further studies."

Under Re-evaluation since 2009

The author obtained information from the PMRA that imidacloprid has been under re-evaluation since 2009. However, there is no indication on the website that this is the case, no apparent effort to inform the public. The author sought relevant documents under the Access to Information Act, but the request has been referred to the "Health Canada Media Relations staff, as is now the policy for all journalists' inquiries."

What we do know, as posted on the PMRA website, is that in 2010 the agency received at least three reports of unusually high bee mortality in Quebec. The investigation reports state that it was "highly probable" that the deaths were due to clothianidin or thiamethoxam.

To date the PMRA data base shows a total of 81 registrations for five neonicotinoid insecticides: imidacloprid, acetamiprid, clothianidian, thiacloprid and thiamethoxam. Of these, 33 are for agricultural use, the rest being for use on trees, golf courses and lawns, in greenhouses, and as flea and tick treatments for pets.

Canada's pest management agency rationalizes these approvals by claiming that the risk to bees is "mitigated" by putting labels on the products that prescribe safe application rates and practices. Such labels tell farmers not to apply the insecticide when plants are in flower or bees are nearby. However, this ignores the fact that the neonicotinoids are systemic insecticides that are absorbed into every part of the plant; neonicotinoids that coat the seed at planting time are transported to the pollen and nectar.

Value to Food Production

In every case, these pesticides are approved for use on the basis of their "value" to human food production and other benefits. But there has been no serious consideration of what the loss of bees takes away from food production. A study by the Food and Agriculture Organisation of the United Nations (FAO) found that some 100 crop species provide 90% of food worldwide, and 71 of these are bee-pollinated.

The collapse of domestic and wild bee populations would be simply disastrous for the human race. This is why a number of scientific teams have been racing to determine the cause of their decline; yet, in the name of protecting food, the PMRA and other agencies in the US and Canada are ignoring the evidence – at the very time when climate change and peak oil already pose serious and massive threats to food security.


Anne Sherrod is a director of the Valhalla Wilderness Society. She has been writing on environmental issues for 35 years.

[From Watershed Sentinel March/April 2012 issue]

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