Colony Collapse Disorder, is Imidacloprid the Culprit?

Image by Lela Dowling

To the average “Joe” bees are more of annoyance then vital link in the food chain. Without the honey bee one third of the food produced would be in jeopardy. Bees are trucked around the countryside to farms and orchards to accomplish pollination on a mammoth scale.

These important insects are fast becoming in major peril due to what scientist are calling Colony Collapse Disorder or CCD.


In recent years, a new group of nicotine-synthesized pesticides have emerged called neonicotinoids. The most common is imidacloprid; many of us know this insecticide as Merit®. Ironically, these were originally manufactured to be less lethal. But about five years ago, French and Italian beekeepers complained that imidacloprid crop spraying was killing their honey bees. So the French and Italian governments banned the neonicotinoid insecticide, in subsequent years Germany has also banned imidacloprid.

American scientists now studying the Colony Collapse Disorder wrote in their first preliminary report that even though the neonicotinoids will not kill adult bees directly on flowers and plants:

“Recent research tested crops where seed was treated with imidacloprid. The chemical was present, by systemic uptake, in corn, sunflowers and rape pollen in levels high enough to pose a threat to honey bees. Additional research has found that imidacloprid impairs the memory and brain metabolism of bees, particularly the area of the brain that is used for making new memories.

If bees are eating fresh or stored pollen contaminated with these chemicals at low levels, the pesticides might not cause mortality, but might impact the bees’ ability to learn or make memories. If this is the case, young bees leaving the hives to make orientation flights might not be able to learn the location of the hive and might not be returning, causing the colonies to dwindle and eventually die. It is also possible that this is not the sole cause of the dwindling bee population, but one of several contributing factors.

A Pennsylvania honey beekeeper that has had nearly 2,000 of his 2,900 hives disappeared - a 60% loss. That is David Hackenberg of Hackenberg Apiary in Pennsylvania. He said he had never seen so many deserted hives that were also left alone by predator moths and beetles. That’s why he suspects some kind of pesticide is getting into the flower pollen and nectar and poisoning the hives. He contacted Penn State’s bee experts to investigate. But to date, there is no definite answer. Below are Part 1 and 2 of a past CBS 60 Minute Episode covering this story.





Bees are still disappearing in massive numbers. One Midwestern beekeeper had 13,000 healthy, full hives. Those bees began disappearing and now he’s lost 96% of them. He’s facing bankruptcy. Additionally, one Ohio beekeeper opened up his hives after the winter to find 80% were empty. Over the last several years, massive disappearances of honey bees have been reported in at least 34 states; internationally in Poland and Spain; and it’s still unknown how many more honey bees will be gone in North America and Europe. Right now, dozens of scientists are trying to find out what exactly is causing Colony Collapse Disorder, or CCD.

Dr. Cox-Foster, entomologist at Pennsylvania State University has seen as many as five different viruses and unidentified fungi in the bees. She says that these study specimens have two times more pathogens than she’s ever seen before in honey bees. The implication is that something has seriously damaged their immune systems, leaving the honey bees more vulnerable to disease than before. But what could that be?

Jerry Hayes, Chief, Apiary Section, Florida Dept. of Agriculture, said in an interview, “The interesting thing about the Colony Collapse Disorder is that bees are leaving the colony and not coming back, which is highly unusual for a social insect to leave a queen and its brood or young behind. They are seemingly going out and can’t find their way back home.

Imidacloprid structure - Image from Wikipedia

Imidacloprid, when it is used to control termites, does exactly the same thing. One of the methods it uses to kill termites is that the termites feed on this material and then go out to feed and can’t remember how to get home. And it also causes their immune systems to collapse, causing what would be normal organisms to become pathogenic in them.”

Hayes also said in that same interview, “I think a couple of things (in reference to imidacloprid). First, its use has changed. At first it started out as a seed treatment to protect the seed as it germinated and developed. Now it is being used as a foliage spray, a granular, it’s being used as a systemic; it’s being combined with fungicides, which increases its efficacy. So, its use has changed. Especially systemically, it does what it’s supposed to do - it takes care of agricultural pests, which we want it to do. But there seems to be a disconnect, sometimes that researchers and horticulturists forget that a honey bee is an insect. And of course, there are other insects out there that are valuable pollinators as well.”

So, systemically this material (imidacloprid) is found in the nectar - in many cases in low doses - not something that would kill a honey bee. So the question is: What does chronic exposure to the honey bee, either as an adult, or as the bees bring the material back to the nest to store and feed to developing young bees over time - what does chronic exposure (to pesticides) do to the colony?

Beyond the honey bees, Something is killing all the pollinators. Pollinators include honey bees, bumble bees, hornets, wasps, butterflies, hummingbirds and even bats. Something is happening in the environment that is causing all of those different species to decline - and currently the most dramatic event is the massive disappearance of honey bees.

Repeatedly, Bayer has denied bee declines due to use of their Imidacloprid insecticide. You should limit the use of all insecticides to situations where they are really needed but be especially cautious when using the imidacloprid insecticides until we know more. Click here to view Merit® Label.