Fungicides contribute to declining honeybee populations

WASHINGTON — A surprising study shows fungicides may contribute to what’s killing honeybees.

Researchers at the U.S. Department of Agriculture and the University of Maryland base their findings on pollen collected from honeybee hives in fields from Delaware to Maine.

Fungicides aren’t supposed to harm insects. But they make honeybees two times more likely to come down with an infection compared to bees fed fungicide-free pollen.

“This suggests we need to reconsider how we label fungicides for use,” says Dennis vanEngelsdorp, the University of Maryland professor who is the senior author on the report.

VanEngelsdorp says the good news is that beekeepers can work with the farmers who rent their bees and encourage them to not spray crops while they’re in bloom and bees are foraging. That’s the current rule for use of insecticides.

Researchers testing pollen samples find they contain as many as 21 different pesticides, but the average is about nine. That means whenever bees go out looking for food, “on average they’re bringing nine different potentially toxic chemicals back to the hive with them, which you can’t imagine is very good for honeybee colonies,” says vanEngelsdorp.

The findings do not explain colony collapse disorder that results in entire colonies dying suddenly. But vanEngelsdorp notes bee colonies in general have been in decline for the past six years.

The large number of issues contributing to the decline could require a variety of solutions and approaches to solve, he says.

Each winter, beekeepers lose a third of their hives. The numbers are replenished each summer, but the financial strain could lead to beekeepers going out of business because it’s so expensive to replace the losses every year.

“The industry is really hurting,” says vanEngelsdorp.

About half the bee colonies nationwide are moved across the country through farming seasons to pollinate crops that eventually land on people’s dinner tables.

VanEngelsdorp says it’s not unusual for the same bee colony to pollinate apples in Pennsylvania, blueberries in Maine, cranberries in Massachusetts, cucumbers and melons in New Jersey and almonds in California.

The study is published in the online journal PLOS ONE.

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