Study: Pesticide Mixture the Culprit in Almond Grove Bee Die-Offs

A new study has found that a mix of insecticides and fungicides could be the culprit in massive die-offs of honeybees at almond groves in California’s Central Valley.

Previous research showed that the chemicals do not harm honeybees on their own. It's when these pesticides mingle in the air together — as they do in almond groves — that they become a lethal combination for bees, according to the study from Ohio State University and the Almond Board of California.

“Fungicides, often needed for crop protection, are routinely used during almond bloom, but in many cases growers were also adding insecticides to the mix," wrote Reed Johnson, a bee expert at Ohio State University and one of the study's authors, in an article for Ohio State News.

"Our research shows that some combinations are deadly to the bees, and the simplest thing is to just take the insecticide out of the equation during almond bloom," Johnson said.

During the month of February, trucks full of honeybee hives — some 1.5 million colonies — arrive in California. The bees pollinate the almonds, a crop that’s valued at more than $5 billion a year.

Record die-offs have been documented for years in California. Then, in 2014, things got worse as researchers and farmers observed entire honeybee colonies die.

Johnson and the study's other authors recommend that almond growers completely stop using the pesticides when almond trees are blooming in February.

“Honeybees are essential to almond production,” according to a statement by Bob Curtis, pollination consultant and retired director of Agricultural Affairs for the Almond Board of California. “Every almond we eat exists because a honeybee pollinated an almond blossom so it’s in farmers best interest to keep them safe. Our livelihood depends on it.”

Lily Jamali and Marnette Federis contributed to this report.