Colony Collapse Disorder: Are Potent Pesticides Killing Honeybees?

With a third of honeybee colonies disappearing due to “colony collapse disorder,” it’s time to move into high gear to find a solution.

colony collapse disorder - bee pollination

Two common pesticides have been linked to colony collapse disorder symptoms in honeybees.


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Colony collapse disorder has wreaked havoc on U.S. beekeeping businesses (and the agriculture industry) since its devastating arrival in 2006. The veiled killer entered hives across Japan for the first time earlier this year, affecting 25 percent of the national beekeeping association members. Now the nonprofit Natural Resources Defense Council (NRDC) is suing the U.S. Environmental Protection Agency (EPA) for withholding details about the impact of neonicotinoids — a class of widely used pesticides — on honeybees and other pollinators.

Nasty Neonicotinoid Pesticides

The EPA identifies two specific neonicotinoids, imidacloprid, and clothianidin, as highly toxic to bees. Both chemicals cause symptoms in bees such as memory loss, navigation disruption, paralysis, and death.

Both chemicals have been linked in dramatic honeybee deaths and subsequent suspensions of their use in France and Germany. Several European countries have already suspended them. Last year Slovenia and Italy also suspended their use for what they consider a significant risk to honeybee populations.

While Bayer CropScience, the primary producer of both pesticides, maintains honeybee deaths reported in Europe were caused by unusual application errors, they don’t dispute the proven toxicity of their products. Instead, they maintain bees do not encounter enough of an exposure to cause harm. Now even that assertion is under the microscope.

A report by Maryann Frazier, senior extension associate at Pennsylvania State University, points to a new study from Italy suggests honeybees may be ingesting neonicotinoids at levels 1,000 times higher than that in pollen or nectar via water droplets expressed from the leaves of corn grown from the pesticide-coated seed. This “guttation water” is a common source of liquid for forager bees. The concentrations in the droplets were high enough to kill bees within five minutes of consumption.

Frazier also highlights a study from North Carolina University that found the neonicotinoid Terraguard and the fungicide Procure had synergistic affects when combined, increasing the danger of the neonicotinoid to honeybees to over 1,000 times its original toxicity. The researchers at Penn State are concerned that even sub-lethal doses of these pesticides, while not killing the bees, are impairing their behavior and suppressing their immune systems.

“Their use has increased dramatically over the past few years and they are now the most widely used group of insecticides in the United States,” writes Frazier.

As usage skyrockets, regulation lags behind. Clothianidin was approved in 2003 with the condition that Bayer must provide research on the chemical’s effects on honeybees. The EPA has received the research, but has yet to release all of it — despite requests from the NRDC, thus prompting the lawsuit. The EPA has also provided 163 emergency exemptions for imidacloprid in 26 states, all with little to no research on the sub-lethal affects being reported by researchers in both the US and abroad. (Emergency exemptions allow unregistered use of a chemical for a limited period of time.)

Bees Are Consuming a Chemical Cocktail

There still isn’t a clear answer to this increasingly desperate honeybee mystery. Neonicotinoids are just one of many chemical killers honeybees are encountering.

The Colony Collapse Disorder Working Team, created by the U.S. Department of Agriculture (USDA), was formed in 2007 to research potential causes. When testing hives for pesticides, they found an overwhelming chemical cocktail.

Diane Cox-Foster, professor of entomology at Penn State and co-director of the CCD Working Team, wrote that the outcome of the tests was “startling.” More than 170 different chemicals, and some individual pollen samples, contained as many as 35 different compounds. But, Cox-Foster notes, “None is likely to be the smoking gun.” Even the healthy colonies contained massive quantities of pesticides, herbicides and fungicides. (Although neonicotinoids weren’t found in this testing, the researchers say they are not discounting them as a possible contributor to colony collapse.)

In addition to the chemical component, the CCD Working Team is looking into a number of other collaborators that have risen to the surface including the Israeli Acute Paralysis Virus, a new strain of the nosema fungus, a widely used miticide called fluvinate, and a poor diet as a consequence of monoculture feeding. Although all have been discounted as singular causes of CCD, they have been identified as serious concerns potentially working in concert with other stressors. And, most recently, the fungicide chlorothalonil has been mentioned as a potential issue to investigate.

Safe, or Seriously Toxic?

While neonicotinoids are encountered outside of the hive, there is another chemical hiding inside that may be having an unprecedented affect: Fluvinates (specifically tau- fluvalinate) are chemicals beekeepers use to keep mites in check. But increased resistance to the miticide and changes in the formula over time are raising red flags for researchers. “Unprecedented amounts of fluvalinate at high frequencies have been detected in brood nest wax and pollen,” Frazier says.

Most beekeepers would consider the common miticide relatively harmless to their bees when properly applied. When the chemical was initially released on the market in the 1980s, the beekeepers’ assumption would have been correct. By the early 1990s a new formula had been released that doubled the toxicity of the chemical, but it was still classified as only moderately toxic to honeybees. By 1995, the EPA reported fluvinate as highly toxic to honeybees. How did this chemical go from safe to seriously toxic to the very pollinators it is supposed to help without much, if any, concern by the EPA?

Researchers at the Penn State department of entomology state in a report released in 2008, “Due in part to the high cost of bringing pesticides to market, companies may make existing pesticides more effective or overcome resistance by changing their chemistry or reformulating them.” They also highlight the fact that the US registration of fluvinate “changed hands” a number of times over the last 20 years, meaning the formulation may very well have changed with each hand-off.

Bees: Vital to Our Food Supply

The USDA has stated that one out of every three bites of food we eat is dependent on bee pollination. We have the opportunity to take a look at yet another facet of our industrialized food system. Just how precipitous has feeding ourselves become when a third of our nation’s food supply is reliant on convoys of thousands upon thousands of imported and artificially sustained bees crisscrossing the nation? As one researcher asked Congress, “How would our government respond if one out of every three cows was dying?”

Beekeepers are having some success staving off colony losses by improving the diet of their bees and keeping a closer watch for parasites and infections, says Cox-Foster. She also suggests “simple changes” such as increasing the use of hedgerows could improve both the honeybee population and that of the wild pollinators.

Like the cause, the solution to CCD is going to have to be multi-faceted. There appears to be no single cause that can be directly linked to colony collapse. Researchers think the disorder is the result of many pest/viral/fungal/chemical/stress combinations. Pesticides, although just a piece of the puzzle, are a variable we can control. By eliminating this variable, research could be focused on deciphering the other pieces of the puzzle. Instead, pesticide regulation loopholes are making it nearly impossible to track down the causes of colony collapse disorder.

6/23/2013 7:23:53 PM

Excuse me but I am a bit skeptical about colony collapse because of whow the dire warnings aren't the proper results. If there is such a threat something akin to the Manhattan Project would be underway.

Consider this: in the "wild" bees move on from time to time to new living quarters. In the commercialized colonies they stay in the same place. Are the hives simply unhygenic after repeated use? Could the beekeepers be capitalizing on losses and driving up their own investment? 

These things need to be studied along side all the other fine work being done.

bob johnson
1/28/2011 1:27:43 PM

What i see here is a distortion of the facts. true, neonictinoids do cause problems, however what you fail to mention, nor consider is the role of Viral infections, bacterial infections, poor pollen quality (from GMO's) and other environmental factors play in the mix. You seem to "just blame the easiest one". Even Germanys interior minister pointed to gross misapplications as a cause of the die offs. What about the gross misapplication of materials here, on a daily basis by homeowners? Now who is the largest applicator of neonictinoids? Homeowners! when you can buy pesticides that are used my professional applicators and put it into the hands of homeowners you are asking for trouble. Those companies that supply these materials to homeowners have been contacted by the manufacturers to stop, only to be told they are in their legal right. It is the responsible public that needs to get involved to have the laws changed to stop this practice of letting homeowners get the materials that are highly toxic to bees. check out "" and see what I mean. Now, I'm not defending Bayer, but there are other problems in addition to the materials that need addressing. Those include "farmed" bees for pollination, (nothing like passing a pathogen load to unaffected colonies) tetracycline resistant Nosema. There are other "structural pests" that neonictinoids help control that aren't part of the problem matrix.

kevin hansen_3
1/22/2010 5:22:09 PM

We just released a new documentary film called Nicotine Bees, on the serious worldwide, simultaneous die-offs of the honeybee, with the help of the Sierra Club. We filmed across the US, in Germany, in Canada and in India. Three factors seem to implicate neonicotinoids as the most important factor in the bee die-offs: 1) Worldwide extent of the problem; 2) Simultaneous worldwide occurrences of the massive die-offs, beginning in about an 18-month range; 3) Strange and widely-reported bee behaviors; Most other explanations do not seem to pass this 3-part test; We think the situation is grave, worsening, and has very direct explanations - contrary to earlier reports. For example: A) An Italian ban on some nicotine pesticides seems to have immediately stopped CCD phenomena; B) The State of California with EPA has asked for a re-evaluation of 282 pesticides in connections with honeybee die-offs - one of the important reasons was the persistence in soil not evaluated prior to registration. Kevin Hansen, LEED AP, PG Director, Nicotine Bees the movie

frank kling
10/13/2009 2:01:00 AM

One would logically think that the chemical companies would be required to do an environmental impact study prior to the release of toxic organic pesticides, but no that would be hurtful to the profits of big business according to the Bush administration EPA. Instead we depend upon not-for-profit environmental groups to expend scarce resources. What a damn shame.

paul barthle
10/12/2009 9:49:36 PM

I had often wondered if GMO corn pollen containing the genes for BT could have had anything to do with bee losses as well? Has there been any research on this as a contributing factor? By the way, a Bayer statin drug was only taken off the market after numerous humans fell ill as a result of a nasty side effect that some experienced. I'm not saying that there could be a connection, I'm just sayin'!

10/12/2009 11:24:23 AM

Potent insecticides? Hah! I can't buy anything that will reliably kill the pests in my yard other than pouring gasoline on them!

laurel hopwood
9/20/2009 3:48:28 PM

Beekeepers are telling us - look at the new releases. For years, farmers have been spraying neonicotinoids onto their crops to stop insect infestation. Now Monsanto, Bayer, and Syngenta have acquired patents to coat their proprietary corn seeds with these neonicotinoids. Colony Collapse Disorder started after these coated corn seeds were planted. Neonic's are being found in the nectar, pollen, and soil for a long time. When bees are exposed to neonic's, they can't find their way home. For more info, visit Laurel Hopwood, Chair, Sierra Club Genetic Engineering Action Team