Zombie honey bees were first discovered in the San Francisco Bay area in 2012. Though the creature sounds like something out of a bad horror movie, it is actually the nasty result of parasitism, and a potential explanation for Colony Collapse Disorder (CCD) across the United States.

The phorid fly Apocephalus borealis is native to North America, and its breeding method is an insidious process that would indeed be right at home in a horror film. The fly infects a honey bee by injecting its ovipositor into the bee’s abdomen and filling it with its eggs. The bee then exhibits “zombie-like” behavior, becoming increasingly disoriented, breaking away from its hive and seeking out light sources at night – a time when bees are typically inactive. The bee dies when the fly’s larvae eat their way out of its body.

 A. borealis ovipositing eggs into the abdomen of a worker honey bee

A. borealis ovipositing eggs into the abdomen of a worker honey bee

According to San Francisco State Professor of Biology John Hafernik, who led the original research on the subject, up to 13 fly larvae can emerge from a dead, zombified bee.

Apocephalus borealis was not unknown to researchers prior to Hafernik’s study, but until 2012 they had only been documented parasitizing bumblebees and paper wasps. Though North American honey bees are afflicted by parasitic mites, fungal parasites and viral diseases, they were relatively untroubled by parasitoid insects. Hafernik’s initial study, published in the journal PLOS ONE, states that “honey bees are attacked by numerous species of phorid flies” in South and Central America, “almost none of which occur in North America.”

The Hafernik study established “A. borealis as a novel parasite of honey bees and documents hive abandonment behavior consistent with a symptom of CCD. This is a cause for concern because other species of phorid flies can dramatically affect social insect behavior.”

Since that time, ZomBeewatch has emerged as a citizen science project to track the occurrence of parasitized honey bees. At first, the “zombees” were limited to South Dakota and the West Coast, but in 2013 sightings were confirmed in New England. Recently, Sherry Grenzberg, a Pennsylvania beekeeper, confirmed that zombees have reached the mid-Atlantic coast.

“This finding raises questions about whether we might be seeing the early stages of a host shift to honey bees by Apocephalis borealis in the mid-Atlantic region or whether this is something that has gone unnoticed for a number of years,” Hafernik told Phys.org. “Sherry’s discovery also emphasizes the important contributions that citizen scientists can make to research on honey bee health, even in a relatively well-studied state like Pennsylvania.”

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