According to Tom Theobald, a Boulder Colorado bee keeper, chlothianidin is causing the decline of bee colonies. How and when did the bees get poisoned?
“These neonicotinoids are huge. This is the insecticidal equivalent of plutonium,” said Tom Theobald, in a phone interview on October 26, 2011. In my last blog post, I asked whether chlothianidin was responsible for CCD. To some, to Tom Theobald, there is no doubt.
Long before CCD became a national story in 2006, Tom Theobald had been experiencing unusual losses among his honey bee colonies. As early as the winter of 1995, with the appearance of the varroa mites, the Colorado bee keeper’s colonies had suffered serious declines, their hives being abandoned, teeming with honey that other bees failed to forage. The varroa mite was considered the culprit at the time. As its impact diminished, the winter losses, however, continued to escalate. This escalation coincided, in Theobald’s view, with the introduction of the pesticide Imidachloprid.
Imidacloprid, first registered for use in the US by the EPA in 1994 and banned in France since 2004, in Germany and Italy since 2008 , is a neonicotinoid that systematically penetrates the plant and is used to control sucking and chewing insects. It penetrates the insect’s nervous system, blocking its neural pathway that, in insects, is more abundant than in warm-blooded animals. The insect that sucks on the treated crop will become paralysed and die. Imidacloprid is in fact known to be highly toxic to bees. In 2003, when its patent ran out, it was replaced by another neonicotinoid, chlothianidin.
On his Colorado honey farm, Tom Theobald set out like Sherlock Holmes to try to explore the mystery of his disappearing bees. His colonies had ended the summer strong: “the brood nest was the size of a basketball.” Yet somehow, by October, the brood nest had suffered a precipitous decline in size – “it had become the size of a softball.” The colony of 30,000 bees had declined to 3,000. Puzzled by this decline and given the absence of varroa mites, he figured that the queen must have either stopped laying, stopped laying viable brood, or that the larvae were dying. This period in the fall, when the colony is producing the winter brood, is a crucial one: there must be a critical mass of bees to protect the colony, to serve as the outer layer, the “sacrificial blanket” as it were of the hive that keeps the dormant bees warm throughout the cold winter months. With the break in the brood cycle, there was no winter layer and the colonies simply collapsed.
Why this sudden arrest in procreative activity? Theobald looked over to the surrounding corn fields. The corn pollen contained the neonicotinoid chlothianidin known to compromise the fertility of the queen and the viability of the brood, as explained in the PAN pesticides Database: “Population-level effects on honeybees may occur even if a pesticide has low acute toxicity. For example, certain pesticides interfere with honeybee reproduction, ability to navigate, or temperature regulation, any of which can have an effect on long-term survival of honeybee colonies. The neonicotinoids, pyrethroids and keto-enol pesticides are some types of pesticides causing one or more of these effects.”
The bees, Theobald explained in his interview, will store pollen and not use it as long as there is fresh pollen available. Thus the pesticide-laden corn pollen culled in the summer got “stored in the pantry” until the supply of fresh pollen ran out. At that point, around October, the neonicotinoid of the stored pollen attacked the queen’s reproductive system.
When the summer bees die, having worked themselves to death, winter bees normally replace them. Now Theobald’s summer bees had died and there were no winter bees to take over and repopulate the colony.
Chlothianidin will enter its tenth year on the market and it has yet to meet the requirements of registration. When chlothianidin was approved in 2003, there was no pressing insect scourge, Theobald points out, that required immediate approval of the pesticide. What was running out was Bayer‘s, the manufacturing company’s, patent for Imidacloprid. So today, as he says, “we are subjected to all this damage not to protect the world against an insect but to protect Bayer’s market share.”
Given the risks and the damages, is there then any advantage to the use of these neonicotinoids? No. Not only is it killing the bees, according to Theobald, but it is poisoning the soil: “If you are a farmer and you get on this boat, what does your soil look like in five years? You don’t have soil. You have real estate.” As chlothianidin has a half life of nineteen years, it takes over 100 years for the soil to purge itself of the chemical. While the effect on the bees’ neural receptors is cumulative and irreversible, Theobald admonishes “it goes way beyond the bees.”