One Stab Of The Apocephalus Borealis Fly Creates 'Zombie Bees' Out Of East Coast Honey Bees
A worrisome new threat to beleaguered honey bees has reared its head in Burlington, Vermont, the Associated Press reported Wednesday, after a beekeeper there found evidence of so-called "Zombie bees" among his hives. His bees had been rendered insane by being stabbed by female flies Apocephalus borealis intent on laying their eggs inside the bees' bodies. Vermont State Apiculturalist Steve Parise has confirmed that the Apocephalus borealis has been detected in Vermont and the affected honey bees are undergoing testing at San Francisco State University. John Hafernik, a researcher and professor of biology there, has started a website tracking the discovery of infected honey bees in the United Stated called "Zombee Watch."
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The way the fly goes about killing the bee isn't pretty. The female Apocephalus pierces the bee's abdomen with a sword-like tube and deposits her eggs. The developing larvae have no qualms about attacking the bee's brains, disorienting it into flying at night; hence the name, zombie bee. Usually the poor bee dies within a few hours of exhibiting zombie bee behavior — fortunate because, about seven days later, up to 13 mature Apocephalus borealis will "hatch" at where the bee's thorax meets its head, decapitating the bee in the process; hence the name, Apocephalus.
If left unchecked, the parasite could seriously jeapordize U.S. honey bees, whose populations have already taken a nose-dive from Colony Collapse Disorder (CCD), which is when worker bees abandon their hives. As if causing insanity and death in the honey bee weren't enough, the Apocephalus borealis may actually be a vector in the spread of pathogens responsible for CCD, according to Dr. Andrew Core, also of San Francisco State University, who wrote about it in 2012. He found that 77 percent of the hives he sampled in the San Francisco Bay Area had been infected by the parasite. He also found the parasites in commercial hives in California's Central Valley and South Dakota.
Core also found that honey bees from infected hives were often infected with deformed wing virus and Nosema ceranae, a small parasite. "Larvae and adult phorids also tested positive for these pathogens, implicating the fly as a potential vector or reservoir of these honey bee pathogens. Phorid parasitism may affect hive viability," he wrote, adding that infection by the Apocehalus borealis may shed light on similar hive abandonment behaviors seen in CCD.
The Apocephalus borealis is a species of North American parasitoid fly that typically insert their eggs into wasps and bumble bees, not honey bees. But about a year ago, the biologists at San Franciso State were alarmed to find that the Apocephalus were attacking honey bees, too. Sure enough, their DNA barcoding of larvae from dead honey bees confirmed that the fly focused its ferocious egg-laying on them as well. In an article in the online journal PLOS1, Core and his co-authors provided the first proof that "the phorid fly, Apocephalus borealis, previously known to parasitize bumble bees, also infects and eventually kills honey bees and may pose an emerging threat to North American apiculture," or bee-keeping.
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