Researchers Find Direct Link Between Honeybee Deaths and Pesticide

COMMENTARY: When we have a widespread phenomenon like Colony Collapse Disorder, it's natural to think that there is a single cause that we can pinpoint. If we find evidence of a parasite killing honeybees in one area, but no signs of similar parasitic infection in honeybees dying off at another location, the tendency is to rule that out as the singular cause of the rapid decline of honeybees in the United States. It's 1970's tobacco company logic: even if smoking does cause lung cancer, you can't prove it caused your lung cancer so we are not liable.

We know of several widespread factors that can decimate honeybee hives. While none is singularly responsible for all the lost hives, together, the causes of the recent widespread loss of honeybee hives are responsible for the death of roughly one third of all the remaining honeybees in the United States each year.

In 2008, the EPA knew that insecticidal coatings used to protect corn and soy seeds. In an EPA report relating to an investigation of a colony collapse incident in Germany, the EPA said that the destruction of honeybee colonies "would be expected if a large amount of any chemical that is toxic to bees was blown into the air on a dry, windy day next to blooming canola fields for which thousands of hives were providing pollination services." They noted that in the particular case in Germany, pesticide treated seeds were planted by a machine that incidentally blew very fine pesticide residue powder into the air as it planted seeds. The pesticide was intended to stick to the seeds, but much of it rubbed or was blown off during planting.

So we knew then, in 2008, that practices common in the United States, as well as Germany, under some conditions, would result in wholesale die-offs of honeybees and the loss of large numbers of hives and even complete colonies, just as we knew that smoking caused cancer in the 1970's as much as big tobacco wanted to deny it. Now, we have the smoking gun.

According to a report published in the scientific journal PloS One, a group of Purdue researchers responding to reports of widespread honeybee deaths occurring around the time of corn planting season, took samples from the bees, nearby pollen sources, soil in the area and other possible sources of contamination and found that clothiandin, the same seed coating pesticide found to have killed the German bees years earlier, "was found on all the dead and dying bees we sampled, while the apparently healthy bees we sampled from the same locations did not contain detectable levels of clothianidin. Atrazine and metolachlor were also found, providing further evidence that these bees were foraging near agricultural fields; as these herbicides are commonly applied prior to or during maize planting."

The Purdue report even identifies common practice of using talc in planting equipment as a primary vector for the dispersal of clothiandin into the air and that nearly all of the non-organic corn planted in the United States each year is treated with the poison prior to planting. Corn is planted, the researchers note, on 37.5 million hectares of farmland in the United States, covering more land area than any other U.S. crop.

We know that the widespread occurrence of Colony Collapse Disorder in honeybees in the United States is caused by several factors and also occurs in areas where corn is not widely planted. Just because clothiandin and similar seed coating compounds are not killing all the dying honeybees, though, doesn't let those who use and make the chemical off the hook. Based on the evidence, clothiandin is a primary cause of large-scale honeybee deaths in certain regions of the United States. I'll also note that honeybees are not the only insect that feeds on or comes into contact with this contaminated pollen. Butterflies and many other beneficial insects are also directly impacted. The EPA must move to prevent the use of clothiandin and other nicotinoid seed coatings in ways that allows them to become airborne where they can contaminate the pollen of neighboring crops and wild plants, killing entire colonies of honeybees.