While many studies have been conducted on how insecticides used on crops may affect honey bee health, a new study by researchers at the University of Maryland and the U.S. Department of Agriculture suggests that honey bees may be negatively affected by something completely different — fungicides.
The researchers gathered pollen from honey bee hives and analyzed it to see what agricultural chemicals it contained, including fungicides, insecticides, herbicides and miticides. They then fed the pollen to honey bees and tested their ability to resist infection from Nosema ceranae, a pathogen of adult honey bees that has been linked to a lethal phenomenon known as Colony Collapse Disorder (CCD).
In the study’s most surprising result, bees that were fed pollen containing a fungicide called chlorothonatil were nearly three times more likely to be infected by Nosema than bees that were not exposed to it.
“We don’t think of fungicides as having a negative effect on bees, because they’re not designed to kill insects,” said Dennis vanEngelsdorp, one of the authors. “But the study’s finding that common fungicides can be harmful at real world dosages is new, and points to a gap in existing regulations.”
In another unexpected finding, most of the crops that the bees were pollinating appeared to provide their hives with little nourishment. When the researchers collected pollen from bees foraging on native North American crops such as blueberries and watermelon, they found the pollen came from other flowering plants in the area, not from the crops. This is probably because honey bees, which evolved in the Old World, are not efficient at collecting pollen from New World crops, even though they can pollinate these crops.