Fungicide Causing Deaths in Honey Bees

Honey bees are quickly disappearing from flowers and fields. They are succumbing to disease and colony collapse disorder. Now, scientists may have found part of the reason why these insects are dying; they've discovered that fungicides, could be responsible for bees'  unable to fight off a potentially lethal parasite.

Honey bees are an important to the ecosystem, pollinating flowers that will produce fruit and seeds. Farmers rent bees or keep bees of their own in order to help pollinate crops and produce higher yields. Over the years, these insects have begun to disappear. Researchers found that beekeepers lost 31 percent of their colonies in late 2012 and early 2013.

In order to see what was affecting these bees, researchers collected pollen from honey bee hives in fields from Delaware to Maine. They then analyzed the samples to find out which flowering plants were the bees' main pollen sources and what agricultural chemicals were being introduced into the pollen and, consequently, the honey. In addition, the scientists fed pesticide-laden pollen samples to healthy bees and then tested them for their ability to resist infection with the parasite Nosema ceranae. This parasite affects adult honey bees and has been linked to colony collapse disorder.

In the end, the researchers found that the pollen samples contained 9 different agricultural chemicals. These included fungicides, insecticides, herbicides and miticides. In addition, they discovered that sublethal levels of multiple agricultural chemicals were present in every sample; in fact, one contained as many as 21 different pesticides. The most prevalent of these were the fungicide chlorothalonil and the insecticide fluvalinate.

They didn't just find these chemicals present in the honey, though. The researchers found that bees fed pollen samples containing chlorothalonil were nearly three times more likely to be infected by the deadly parasite Nosema than bees that were not exposed to these chemicals. This is a huge finding in terms of determining exactly what may be harming these insects.

"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 researchers.

Federal regulations restrict the use of insecticides while bees are foraging, but that isn't the case with fungicides. "But there are no such regulations on fungicides, so you'll often see fungicide applications going on while bees are foraging on the crop. This finding suggests that we have to reconsider that policy."