Parasitic fly could explain bee die-off
FRESNO, Calif. — Northern California scientists say they have found a possible explanation for a honey bee die-off that has decimated hives around the world: A parasitic fly that hijacks the bees’ bodies and causes them to abandon hives.
Scientists say the phorid fly, or apocephalus borealis deposits its eggs into the bee’s abdomen, causing the infected bee to exhibit zombielike behavior by walking around in circles with no apparent sense of direction. The bee leaves the hive at night and dies shortly thereafter.
The symptoms mirror colony collapse disorder, in which all the adult honey bees in a colony suddenly disappear.
The disease is of great concern, because bees pollinate about a third of the United States’ food supply. Its presence is especially alarming in California, the nation’s top producer of fruits and vegetables, where bees play an essential role in the $2 billion almond industry and other crops.
The latest study, published Tuesday in the science journal PLoS ONE, points to the parasitic fly as the new threat to honey bees. It’s another step in ongoing research to find the cause of the disease.
Researchers haven’t been able to pin down an exact cause of colony collapse or find a way to prevent it. Research so far points to a combination of factors including pesticide contamination, a lack of blooms — and hence nutrition — and mites, fungi, viruses and parasites.
“We don’t fully understand the web of interactions,” lead investigator John Hafernik said. “The parasite could be another stressor, enough to push the bee over tipping point. Or it could play a primary role in causing the disease.”
Hafernik stumbled onto the parasitic fly by accident. Three years ago, the biology professor looked for something to feed a praying mantis. He found some bees outside his classroom, placed them in a vial and forgot about them. When he looked at the vial a week later, he found dead bees surrounded by small fly pupae. A parasitic fly was feeding on the bees and had killed them, he said.
The fly is a known parasite in bumble bees. Scientists used DNA bar coding to confirm the parasite in the honey bees and bumble bees was the same species.
