Use of imidacloprid - common pesticide - linked to bee colony collapse

The likely culprit in sharp worldwide declines in honeybee colonies since 2006 is imidacloprid, one of the most widely used pesticides, according to a new study from Harvard School of Public Health (HSPH).

The authors, led by Alex Lu, associate professor of in the Department of Environmental Health, write that the new research provides "convincing evidence" of the link between imidacloprid and the phenomenon known as (CCD), in which adult bees abandon their hives.

The study will appear in the June issue of the Bulletin of Insectology.

"The significance of bees to agriculture cannot be underestimated," says Lu. "And it apparently doesn't take much of the pesticide to affect the bees. Our experiment included pesticide amounts below what is normally present in the environment."

Pinpointing the cause of the problem is crucial because bees—beyond producing honey—are prime pollinators of roughly one-third of the crop species in the U.S., including fruits, vegetables, nuts, and livestock feed such as alfalfa and clover. Massive loss of honeybees could result in billions of dollars in agricultural losses, experts estimate.

Lu and his co-authors hypothesized that the uptick in CCD resulted from the presence of imidacloprid, a neonicotinoid introduced in the early 1990s. Bees can be exposed in two ways: through nectar from plants or through high-fructose corn syrup beekeepers use to feed their bees. (Since most U.S.-grown corn has been treated with imidacloprid, it's also found in corn syrup.)

In the summer of 2010, the researchers conducted an in situ study in Worcester County, Mass. aimed at replicating how imidacloprid may have caused the CCD outbreak. Over a 23-week period, they monitored bees in four different bee yards; each yard had four hives treated with different levels of imidacloprid and one control hive. After 12 weeks of imidacloprid dosing, all the bees were alive. But after 23 weeks, 15 out of 16 of the imidacloprid-treated hives—94%—had died. Those exposed to the highest levels of the pesticide died first.

The characteristics of the dead hives were consistent with , said Lu; the hives were empty except for food stores, some pollen, and young bees, with few dead bees nearby. When other conditions cause hive collapse—such as disease or pests—many dead bees are typically found inside and outside the affected .

Strikingly, said Lu, it took only low levels of imidacloprid to cause hive collapse—less than what is typically used in crops or in areas where bees forage.

Scientists, policymakers, farmers, and beekeepers, alarmed at the sudden losses of between 30% and 90% of since 2006, have posed numerous theories as to the cause of the collapse, such as pests, disease, , migratory beekeeping, or some combination of these factors.

Explore further

Honeybees entomb to protect from pesticides

More information: "In Situ Replication of Honey Bee Colony Collapse Disorder," Chensheng Lu, Kenneth M. Warchol, Richard A. Callahan, Bulletin of Insectology, June 2012
Citation: Use of imidacloprid - common pesticide - linked to bee colony collapse (2012, April 5) retrieved 20 October 2019 from
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Apr 05, 2012
the hives were empty except for food stores, some pollen, and young bees, with few dead bees nearby.

Somehow this reminds me of the story of an unfortunate antarctic expedition party that left their base camp equipped with a writing desk and tins of shoe polish, because all their food was packed in cans sealed with lead and they became delirious due to lead poisoning.

Apr 05, 2012
I hope Anonymous et al. will shut down Bayer, makers of Imidicloprid, and to do the same to Monsanto while they're at it. Bayer was an operator of slave labor camps in Germany during World War II, and Monsanto is breaking the backs of independent farmers to force all produce to be Monsanto's GMO's.

Apr 05, 2012
Eikka, that is the most hilarious thing I have heard in, years. LOL.

Apr 05, 2012
If that's the most hilarious thing you've heard in years, you have the most unenviable life I've heard of in years.

Apr 05, 2012
I watched a documentary about CCD, apparently French farmers learned that this was the problem almost 10 years ago and have had the pesticide banned shortly after.

Apr 05, 2012
The imidacloprid is definitely not a vitamin, but I will still keep my theory of food allergy of bees CCD, induced with GMO pollens. For example, the bats, which are suffering with white-nose syndrome by now in similar way, like the bees are consuming pollens too - but they're not affected with imidacloprid being mammals.

Apr 05, 2012
have had the pesticide banned shortly after
Yep, this is the point. Did it really helped? I would say not. IMO imidacloprid is the step in the right direction and it can even contribute to the poisoning of bees significantly - but the real origin may be even deeper. We cannot believe in anything here.

In October 2009, Dan Norris the Parliamentary Under-Secretary of State for Environment, Food and Rural Affairs gave this rather furtive answer in response to Taylor's question during oral questions on Environment, Food and Rural Affairs, 29 [15]:
"There is no evidence that authorised pesticides pose an unacceptable risk. However, I understand why my Honorable Friend asks his question: where somebody is paying, one questions whether the research will be reflective of scientific rigour or not."

Apr 05, 2012
"Mutagenic effects
Imidacloprid may be weakly mutagenic13. In tests of the ability of imidacloprid to cause genetic damage submitted to the EPA as a part of the registration process, no evidence of genetic damage was found, or evidence only at high exposures. However, a new technique that looks at the ability of a chemical to cause genetic damage by chemically binding to DNA found that the imidacloprid insecticide Admire, increased the frequency of this kind of damage. DNA adducts (the binding of a chemical to DNA) were five times more common in calf thymus cells exposed to Admire than in unexposed cells."

Apr 05, 2012
"Mutagenic effects Imidacloprid may be weakly mutagenic13.
It's indeed nice, because the imidacloprid is a common component of popular flea killer applied directly to the skin of dogs and cats and/or the component of widespread insecticides applied against cockroaches at living houses in the form of spray.

Apr 05, 2012
"Many and perhaps most Americans believe that commercially available pesticides, such as those found in pet products, are tightly regulated by the government. In fact, they are not. Not until the passage of a 1996 law focused on pesticides in food did the Environmental Protection Agency (EPA) begin examining the risks from pesticides in pet products in earnest. To this day, the EPA allows the manufacture and sale of pet products containing hazardous insecticides with little or no demonstration that a childs exposure to these ingredients would be safe. Just because these products are on store shelves does not mean they have been tested or can be presumed safe.

Of course, as bad as these products may be for pet owners and caregivers, they often are worse for the pets themselves. Based on the very limited data available, it appears that hundreds and probably thousands of pets have been injured or killed through exposure to pet products containing pesticides.

Apr 06, 2012
Go away Tennex/Zephyr/Callippo. You've spawned a hell of a lot of sockpuppets recently. Bored?

Apr 08, 2012
In this connection it's symptomatic, the usage of imidacloprid was banned in France before fifteen years, in Slovenia before nine years already - and this time took the scientists in the USA and Germany to realize it. Imidacloprid is successful and well sold product of Monsanto and Bayern companies.

What's next? Cytotoxic and DNA-damaging properties of glyphosate and Roundup in human-derived buccal epithelial cells.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more