Agricultural Chemicals Harm Honeybees' Health

Honeybees play a key role in farming as they are used to pollinate a wide selection of crops from apples to watermelon. But a recent study found that chemicals used in farming can impair a bees' health, according to Eureka Alert.

Exposure to agricultural chemicals like fungicides, insecticides, herbicides, and miticides can impair bees' ability to fight life-threatening parasites, say researchers at the University of Maryland and the United States Department of Agriculture.

Researchers collected and analyzed pollen samples from honeybee hives in farm fields from Delaware to Maine. They wanted to find out which flowering plants were the bees' main pollen sources as well as which agricultural chemicals were mixed with the pollen. Healthy bees were fed the pollen samples, then tested for their ability to resist infection with Nosema ceranae, a parasite common in adult honey bees that has been linked to a deadly condition called Colony Collapse Disorder.

The pollen samples contained nine different agricultural chemicals on average, including fungicides, insecticides, herbicides, and miticides. Sublethal levels of many of the chemicals were present in every sample and one sample contained 21 different pesticides. The pesticides most commonly found in the pollen were the fungicide chlorothalonil, used on apples and other crops, and the insecticide fluvalinate, used by beekeepers to control Varroa mites, which are common honey bee pests.

Bees that were fed pollen samples containing chlorothonatil were nearly three times more likely to be infected by Nosema than bees that were not exposed. The miticides used to control Varroa mites also weakened the bees' ability to resist parasitic infection.