Buzz of the Undead
If you were a honeybee, you might scare your children into obedience with tales of the phorid fly, a creature whose depravity sinks to deep depths. Picture this: you’re going about your business, pollinating flowers and the like, when one of these devils swoops in, clamps down on your abdomen and, using a spiked injector called an ovipositor, injects its eggs inside you. Within a few days, maggots hatch from the eggs and start eating your guts, disemboweling you from the inside. Obviously, this is enough to drive anyone demented. As the torture reaches its pinnacle you flee the hive, crazed and confused, and never return. You die a desperate death, vainly spinning in ridiculous circles, under the cold beam of a light that you are inexplicably attracted to. With little respect for your corpse, about a week later as many as 13 phorid fly larvae wiggle their way out of your decaying body, ready to begin the cycle anew by infecting some of your friends.
Bees that meet this grisly end are nicknamed “zombees” because of their disoriented behavior. Californian scientists published a paper in the open-access journal PloS One this January detailing how the fly (Apocephalus borealis which is distinct from the phorid fly the U.S. Department of Agriculture is using to control fire ant populations in Florida and elsewhere) has recently begun parasitizing honeybees in and around San Francisco. The researchers found infected bees in 77 percent of the sites they sampled. Until now, scientists had documented the fly’s impact on only bumblebees and paper wasps.
Honeybees are an important part of the food chain. It is estimated that roughly one mouthful out of every three that people ingest “directly or indirectly benefits from honeybee pollination,” according to the U.S. Department of Agriculture. But the pollinators face a mixture of threats. Since 2006, beekeepers have been reporting higher than normal losses of bees in their colonies. The causes include parasites such as varroa and tracheal mites, and a pathogen called Nosema cerana, which suppresses bees’ immune systems, reducing their ability to fight infections. Pesticides, including a class of widely-used, paralyzing chemicals known as neonicotinoids, may also play a role in bee die-offs. These and other factors could be contributing to Colony Collapse Disorder, wherein adult bees abandon a hive and their queen.
To further investigate how the zombifying flies are contributing to bee deaths, the researchers have launched a citizen science project, charmingly named Zombeewatch.org, to help them track the prevalence of “zombee” infections. Infections have been found in California and South Dakota, according to this map. Phorid flies themselves are much more widespread, so they may also be infecting bees elsewhere.
Map from www.zombiewatch.org showing zombie fly distribution. Red pointers show centers of zip codes where the zombie fly has been found infecting honey bees. Blue pointers show other areas where the zombie fly has been found.
If you suspect you have “zombees” in your vicinity, researches encourage you to collect them for definitive diagnosis. Infected bees are typically found flying around lights at night or on sidewalks, crawling or dead. You can pick them up, with tweezers or forceps, and put them in a jar. More inspired collectors can build a light-trap (instructions available at www.zombeewatch.org). If a bee is infected, brown, “pill-shaped” phorid fly pupae will emerge from its body about five to 14 days later. The researchers ask that people upload photos of all positive results.
Sick bees behave like the victim in this video.
While Westerners might be more concerned with swatting mosquitoes during summer’s balmy evenings, monitoring bees and reporting signs of the undead and dying could help scientists better understand the complex suite of threats honeybees face.
Brendon Bosworth is a High Country News intern.
Image: A female phorid fly (Apocephalus borealis) courtesy Brian V. Brown.