Life

Parasitic fly could account for disappearing honeybees

Bees' burden (Image: Christopher Quock)

Parasitic flies that turn honeybees into night-flying zombies could provide another clue to cracking the mystery of colony collapse disorder.

Since 2007, thousands of hives in the US have been decimated as bees inexplicably go missing overnight. The best explanation so far is that multiple stresses, perhaps parasitic mites, viruses or pesticides, combine to tip the bees over the edge.

John Hafernik of San Francisco State University in California and colleagues discovered that hosting Apocephalus borealis, a parasitic fly found throughout North America, makes bees fly around in a disoriented way at night, when they normally roost in the hive, before killing them.

Although unlikely to be the sole cause of colony collapse disorder, Hafernik thinks the parasitic fly discovery may help explain why bees quit their hives. "They seem to leave their hives in the middle of the night on what we call the 'flight of the living dead'," he says.

Since the discovery, the parasitic flies have been found at 77 per cent of sites in San Francisco Bay, and in hives in South Dakota.

Hafernik's team will now investigate whether the nocturnal flights occur because the parasites affect the bees' "clock" genes, which govern when they are active. It is also possible that contaminated bees are ejected to save the hive.

Journal reference: PLoS One, in press

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