When the early colonists brought honey bees to North America in the 1600s, the bees thrived in their new land becoming our most important pollinator of agricultural crops. Without them, the price of many of our favorite fruits and vegetables might be tracking the rise in gasoline prices. But recently, their future has darkened as they have been threaten by invasions of various demons from Varroa mites, fungal pathogens, deadly viruses, pesticide exposure and most recently colony collapse disorder (CCD). Now they may face a new threat.
One morning a few years ago, I noticed honey bees acting strangely, wandering around in zombie-like fashion on the concrete outside of the biology building where I work. Immediately it came to me -- mantis food! The day before I'd brought back a praying mantis from a weekend field trip with my entomology students. The mantis was hungry. Those stranded bees provided an unexpected opportunity. The mantis devoured the bees, and for days I continued to scoop them into vials to feed them to the mantis. A vial of bees laid forgotten on my desk for over a week. When I looked at the vial again, it was filled with small brown pill-shaped fly pupae.
In science, such unexpected observations are sometimes key to making discoveries. Connecting the dots does not always happen immediately, however.
Two years of study involving SF State students and colleagues, Brian Brown, a fly expert from the Natural History Museum of Los Angeles County (NHMLAC) colleagues from UC San Francisco connected more of the dots. We published our findings in January in the online journal PLoS ONE with my student Andrew Core as lead author.
In short, that forgotten vial revealed that European native honey bees are being parasitized by a native fly, Apocephalus borealis (a.k.a. the zombie fly). Fly-parasitized honey bees show the "zombie-like behavior" of leaving their hives at night on "a one-way flight of the living dead." They soon die and give rise to as many as 16 maggots that pupate and hatch into more zombie flies. 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.
A big question remains, however. How widespread is the threat to honey bees from the fly? To find out, my colleagues and I at SF State and colleagues from the Los Angeles County Museum of Natural History launched a new citizen science website, ZomBeeWatch.org, to enlist the general public and beekeepers from throughout the U.S. and Canada in a "zombee" hunt. By enlisting citizen scientists in a hunt for fly-parasitized bees, we hope to find out how far the parasite has spread and how many honey bee hives are infected with the fly. Volunteer "citizen scientists" can upload photos of their sample's contents to confirm whether they have found a parasitized bee. The locations of confirmed samples are immediately displayed on an infection map showing zombie-fly parasitism of honey bees in North America.
Today's scientific efforts often require bringing together people with the right skills needed to answer particular questions about the natural world. ZomBee Watch is a good example of this. It brings together entomologists with knowledge of insect behavior, computer scientists with skills in programming and design, and the public at large with their observational abilities, their concern for honey bees and their desire to make a difference.
August and September are prime months for "zombee" activity. If all goes well, before long, and with the work of ZomBee hunters from across the continent, we will know much more about the parasitizing flies and their potential to threaten honey bees.
Is the zombie fly the cause of CCD? Probably not -- CCD is most likely caused by multiple factors. Honey bees parasitized by the zombie fly abandon their hive, a behavior associated with CCD. ZomBee Watch endeavors to determine how big a role, if any, the fly plays in hive losses in North America. Will it lead to a "zombee" apocalypse for honey bees or is it a small bit player in a bee horror movie? Observations by the public will help answer that question.