July 24, 2013. Source: University of Maryland
Commercial honey bees used to pollinate crops are exposed to a wide variety of agricultural chemicals, including common fungicides which impair the bees’ ability to fight off a potentially lethal parasite, according to a new study by researchers at the University of Maryland and the U.S. Department of Agriculture.
The study, published July 24 in the online journal PLOS ONE, is the first analysis of real-world conditions encountered by honey bees as their hives pollinate a wide range of crops, from apples to watermelons.
The researchers collected pollen from honey bee hives in fields from Delaware to Maine. They analyzed the samples to find out which flowering plants were the bees’ main pollen sources and what agricultural chemicals were commingled with the pollen. The researchers fed the pesticide-laden pollen samples to healthy bees, which were then tested for their ability to resist infection with Nosema ceranae – a parasite of adult honey bees that has been linked to a lethal phenomenon known as colony collapse disorder.
On average, the pollen samples contained 9 different agricultural chemicals, including fungicides, insecticides, herbicides and miticides. Sublethal levels of multiple agricultural chemicals were present in every sample, with one sample containing 21 different pesticides. Pesticides found most frequently in the bees’ pollen were the fungicide chlorothalonil, used on apples and other crops, and the insecticide fluvalinate, used by beekeepers to control Varroamites, common honey bee pests.