Fly Parasite Turns Honey Bees Into 'Zombies'

The parasites that cause the transformation may provide a clue to the mysterious colony collapse disorder.


- The honey bees become disoriented after the parasite lays its eggs in its abdomen.

- The honey bees abandon their hives in a "flight of the living dead."

- The flies had been determined earlier to parasitize bumble bes.

American scientists have discovered that a fly parasite can turn honey bees into confused zombies before killing them, in an advance that could offer new clues to why bee colonies are collapsing.

So far, the parasite has only been detected in honey bees in California and South Dakota, American researchers reported in the open access science journal PLoS ONE this week.

But if it turns out to be an emerging parasite, that "underlines the danger that could threaten honey bee colonies throughout North America," said the study led by San Francisco State University professor of biology John Hafernik.

Hafernik made the discovery by accident, when he foraged some bees from outside a light fixture at the university to feed to a praying mantis he'd brought back from a field trip.

"But being an absent-minded professor, I left them in a vial on my desk and forgot about them. Then the next time I looked at the vial, there were all these fly pupae surrounding the bees," he said.

Soon, the bees began to die, but not in the usual way by sitting still and curling up. These bees kept trying to move their legs and get around, but they were too weak, said lead author Andrew Core, a graduate student in Hafernik's lab.

"They kept stretching them out and then falling over," said Core. "It really painted a picture of something like a zombie."

Further study showed that bees that left their hives at night were most likely to become infected with the fly parasite, identified as Apocephalus borealis.

Once bees were parasitized by the fly, they would abandon their hives and congregate near lights, a very unusual behavior for bees.

"When we observed the bees for some time -- the ones that were alive -- we found that they walked around in circles, often with no sense of direction," said Core.

The parasite lays its eggs in the bee's abdomen. About a week after the bee dies, the fly larvae push their way into the world, often exiting from between the bee's head and mid-section.

The research, which has also confirmed that the same flies have been parasitizing bumblebees, won local excellence awards when it was first presented last year.

Next, the team hopes to find out more about where the parasitization is taking place, and whether the "zombie bees" leave the colony of their own accord or if their disease is sensed by comrades who then push them out.

Researchers plan to use tiny radio tags and video monitoring to find clues to the mystery.

"We don't know the best way to stop parasitization, because one of the big things we're missing is where the flies are parasitizing the bees," Hafernik said.

"We assume it's while the bees are out foraging, because we don't see the flies hanging around the bee hives. But it's still a bit of a black hole in terms of where it's actually happening."

Experts have theorized that the huge die-off of bees worldwide since 2006, a major threat to crops that depend on the honey-making insects for pollination, is not due to any one single factor.

Parasites, viral and bacterial infections, pesticides, and poor nutrition resulting from the impact of human activities on the environment have all played a role in the decline.

The mysterious decimation of bee populations in the United States, Europe, Japan and elsewhere in recent years threatens agricultural production worth tens of billions of dollars.

Experts have theorized that the huge die-off of bees worldwide since 2006, a major threat to crops that depend on the honey-making insects for pollination, is not due to any one single factor.

Oct. 26, 2012 --

As the Nikon Small World Competition shows, it really is a small world, after all -- a small, disgusting and occasionally creepy world that can sometimes escape our vision. Take this photo, for example, of a Dermatobia hominis larva, more commonly known as the human botfly. The black dots on the far right on the larva's body are actually its teeth, which have to be surgically removed its host.

PHOTOS: It's a Nikon Small World After All

This 30x close-up of a spider head might make your skin crawl at first. But try to remember that this shot is of a common house spider, so there could be a few of these little guys crawling in the space around you right now, and you might not even know it. Feel better?

In case you've ever wondered what the inside of a mouse colon looks like, Christmas came early this year. This is it. Or at least, this is the surface of a mouse colon at 350x magnification.

Whoever thought small things were cute clearly was not acquainted with this parasitic mite. Known as Varroa destructor and seen here at 4x magnification, this mite preys on honey bees and may even play a role in colony collapse disorder.

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This photo would almost be heartwarming were it not an extreme close-up of an insect. An ant carries its larva in this 5x magnification shot.

This 150x magnified shot of a mosquito head is almost enough to make you start scratching an itch you don't really have.

This newborn lynx spiderlings against what appears to be a snowy background shot at 6x magnification can send a chill down your spine that even the heaviest winter coat won't help you with.

The business end of a spider is magnified 18x in this photo.

A mite crawling on the eye of a Cinnabar flat beetle at 18x magnification shows the massive size different between these two insects.

This reflected light photo of a parasitic wasp, Hymenoptera: Eupelmidae, eerily looks like a set of human eyes staring right into the camera.

PHOTOS: Small Worlds Never Before Seen