‘Zombees’ studied by scientists, perform their best ‘Walking Dead’ impressions on the ground

Biologists at San Francisco State University have begun tagging so-called 'Zombees' with tiny radio trackers, to better understand when they abandon their hives and where they go when they do.

A couple of years ago, SF State biology professor John Hafernik made a rather disturbing discovery. For several days, he had been collecting apparently-stranded bees from outside his office to feed a praying mantis he had captured. Forgetting one of the vials of bees on his desk, he returned to it over a week later to find it filled with small brown fly pupae.

After two years of piecing together clues, he found that the European honey bee, brought to North America by colonists, were being parasitized by the native Apocephalus borealis - also known as the Zombie Fly. The fly lays its eggs in a bee's body, and after the larvae hatch and grow, the bee leaves its hive at night, flies erratically, wanders around on the ground near light sources, and then dies. Shortly after death, several maggots emerge from the body and hatch into more zombie flies.

Due to the bee's erratic pattern of walking around on the ground, Hafernik and his colleagues dubbed them 'Zombees'.

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"Whether the fly takes control of a honey bee or whether honey bees flee their hive in an act of altruistic suicide is still an open question." Hafernik wrote in a blog entry on Huffington Post. (On a personal note, given how bees communicate via chemical signals, I'm curious if the larvae set off some kind of chemical 'intruder alert' in the hive and the infected bees are 'ordered' by the hive to leave.)

To learn more, Hafernik and his team set up a hive so that the bees must crawl through a small tube to enter and leave. The entrance to the tube is fitted with a laser reader, similar to a barcode scanner, which scan the tiny radio trackers and record the bees' comings and goings. The original study found that infected bees abandoned their hive at night, but bees do not normally leave the hive at night, because they navigate by the sun. Tracking their movements this way can show if the infected bees fly only at night, and can help the researchers better understand what is happening.

Although the hive-abandonment behaviour of Zombees is similar to what is seen with Colony Collapse Disorder (CCD), Hafernik believes that CCD is not caused by one, but multiple factors. He and his team, along with a citizen watch group called ZomBee Watch, are investigating how much this parasitic infection may contribute to hive collapse.

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