Darn! As if honey bees didn’t have enough problems… Now a new study from San Francisco State and UC San Francisco has added another: Apocephalus borealis.

These parasitic flies will lay eggs in worker bees. We’ll let Ed Yong of Discover take it from there:

Its grubs eventually eat the bees from the inside-out. And the infected workers, for whatever reason, abandon their hives to die.

Even if the bees can avoid the egg laying, A. borealis can still wreak havoc, says ScienceNOW:

In addition, the flies appear to be able to transmit deformed wing virus, which is fatal, and the deadly fungus Nosema ceranae, which causes bee diarrhea.


A. borealis were known to parasitize bumblebees, until San Francisco State entomologists Andrew Core and John Hafernik (also the Academy’s President) found them in honey bees by accident, right outside their building on campus.

After the researchers widened the search, Scientific American reports that:

The team found evidence of the fly in 77 percent of the hives they sampled in the Bay Area of California, as well as in some hives in the state’s agricultural Central Valley and in South Dakota.

Luckily, the flies do little damage to an entire colony, killing off only 5-15% of the worker bees. But researchers speculate that this could be one of the causes of colony collapse disorder, or CCD, which harshly affects honey bee colonies throughout the country. (Watch our story on another possible contributor to CCD here or read about saving the bees here.)

The looming mystery of A. borealis-infected bees appears to be why they abandon their hives, which also occurs in CCD. According to New Scientist:

Hafernik’s team will now investigate whether the nocturnal flights occur because the parasites affect the bees’ “clock” genes, which govern when they are active. It is also possible that contaminated bees are ejected to save the hive.

The research was published online yesterday in the open-access journal PLoS ONE.

Image: Christopher Quock/San Francisco State University

Share This