Parasitic Fly Turns CCD Honeybees Into Zombies


Since 2007, Colony Collapse Disorder (CCD) has puzzled and alarmed scientists and environmentalists nationwide. The strangest part of the mystery is that these social creatures seemed to just disappear, abandoning their hives, leaving behind few bee corpses or clues.  According to a new San Francisco State University study, blame for this behavior can be pinned on a parasitic fly, Apocephalus borealis, not previously known to inhabit the honeybee. The fly has been known to parasitize ants and other bees.

The study, published in the journal PLoS One, claims the parasite is detrimental to 77 percent of honeybee colony sites sampled in the San Francisco Bay Area and was also found in California’s Central Valley and South Dakota. Bees infected with the parasite seem to become disoriented, losing their keen sense of direction that is so valuable to their survival. Coupled with an interference in the bees' circadian rhythm, parasitized individuals may undergo a “flight of the living dead,” uncharacteristically leaving the hive at night, unable to find their way back.

CCD has been blamed on many things, from fungi, bacteria, viruses, and other parasites to industrial beekeeping practices, loss of genetic diversity, loss of habitat, and cell phone towers. The study at hand posits that the parasitic fly found in honeybees could be a reservoir of deadly pathogens and a vector for transmitting them. The authors also hypothesize that, strangely, the behavior of leaving the colony may be an altruistic move by the bees to avoid infecting the other bees.

The 2009 film A Vanishing of the Bees pointed a finger more squarely on new generation pesticides, called systemics, which are blamed for compromising the honeybee immune system, making them more vulnerable to disease. Environmental groups implicate three “neonicotinoid” pesticides in particular: clothianidin, imidacloprid, and thiomethoxam. Indeed, dead bees found at CCD colony sites are riddled with a wide variety of ailments, pointing to compromised immunity. A ban on neonicotinoid pesticides in Italy yielded a recovery of honeybees to normal numbers in 2009.

The U.N. declared CCD a global problem this year, with cases across Europe, Asia, and a suspected case in Egypt. Roughly one-third of worldwide food production depends on bee pollination to some extent, causing a great deal of attention to be paid to the potentially disastrous effects of CCD upon global food supplies. 

However, the real threat of widespread global famine still appears to be population growth, as agricultural demand is growing at a faster rate than that of both production and domesticated honeybee stocks.

Other bee species are in decline across North America. Climate change is destroying or shifting ancient habitats. Scientists say we are in the middle of an anthropogenic mass extinction. Ever since Rachel Carson’s Silent Spring documented DDT poisoning of birds, scientists have studied seemingly benign, low-level exposures to pesticides. While the cell phone tower hypothesis may fall short, I agree with Bill Maher, in that CCD may be Mother Nature’s way of saying, “Can you hear me now?”

Photo Credit: Wikimedia Commons