(3) Widely-used Pesticide Imidacloprid Linked to Colony Collapse Disorder
In an study published in the April issue of the Bulletin of Insectology, Alex Lu, associate professor of environmental exposure biology in the Department of Environmental Health at Harvard University, focused on one neonicotinoid that was introduced in the 1990s, imidacloprid. Bees can be exposed to this chemical either through nectar from plants or from high-fructose corn syrup that beekeepers use to feed their bees. Most corn in the U.S. is treated with imidacloprid, so it is found in corn syrup.
For 23 weeks, the scientists monitored bees in four different bee yards, each of which had been treated with different levels of imidacloprid, and one control hive. All the bees were alive after 12 weeks of imidacloprid dosing. After 23 weeks, 15 of the 16 imidacloprid-treated hives had perished and those exposed to the highest levels of the pesticide were the first to die.
The dead hives showed the characteristics of colony collapse: empty hives with food stores, some pollen and young bees, and only a few dead bees nearby. Had a virus or pest caused hive collapse, there would have been many dead bees inside the hive.
Lu says that his study offers “convincing evidence” connecting imidacloprid to colony collapse disorder. He suggests removing all neonicotinoids from use across the globe for a period of five to six years; if the bee population increases afterwards, neonicotinoids can be clearly pointed to as a culprit.
As Carrington writes, there is no need for testing to see if pesticides harm bees. Even “sub-lethal doses” cause them “serious harm,” and the significance of bees to agriculture and to the global ecosytem is inestimable. What we need is a global ban on imidacloprid, before it is too late.
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