Deadly fly parasite spotted for first time in honey bees

Jan 03, 2012
This shows Phorid larvae exiting a bee. Credit: John Hafernik

Honey bees can become the unwitting hosts of a fly parasite that causes them to abandon their hives and die after a bout of disoriented, "zombie-like" behavior, San Francisco State University researchers have found.

The phenomenon, first observed on the SF State campus, may help scientists learn more about colony collapse disorder (CCD). This mysterious ailment has drastically increased losses across the United States since its discovery in 2006.

So far, the fly parasite has only been found in hives in California and South Dakota, said SF State Professor of Biology John Hafernik. But the possibility that it is an emerging parasite "underlines the danger that could threaten honey bee colonies throughout North America, especially given the number of states that commercial hives cross and are deployed in," Hafernik and colleagues write in the January 3, 2012 issue of .

Hafernik, who also serves as president of the California Academy of Sciences, didn't set out to study the parasitized bees. In 2008, he was just looking for some insects to feed the praying mantis that he had brought back to SF State's Hensill Hall after an entomology field trip. He scrounged the bees from underneath the light fixtures outside the biology building.

"But being an absent-minded professor," Hafernik joked, "I left them in a vial on my desk and forgot about them. Then the next time I looked at the vial, there were all these fly pupae surrounding the bees."

The fly, Apocephalus borealis, deposits its eggs into a bee's abdomen. Usually about seven days after the bee dies, fly larvae push their way into the world from between the bee's head and thorax. But it's the middle part of this macabre story that may be the most scientifically interesting to those studying the dramatic and mysterious disappearance of honey bees.

This is an A. borealis female. Credit: Christopher Quock

After being parasitized by the fly, the bees abandon their hives in what is literally a flight of the living dead to congregate near lights. "When we observed the bees for some time—the ones that were alive—we found that they walked around in circles, often with no sense of direction," said Andrew Core, an SF State graduate student from Hafernik's lab who is the lead author on the study.

Core won first place at the 2011 California State University Research Competition and the Geraldine K. Lindsay Award for excellence in the natural sciences at the annual meeting of the Pacific Division of the American Association for the Advancement of Science for his presentation of the bee research.

Bees usually just sit in one place, sometimes curling up before they die, said Core. But the parasitized bees were still alive, unable to stand up on their legs. "They kept stretching them out and then falling over," he said. "It really painted a picture of something like a zombie."

Bees that left the hives at night were more likely to bear the parasite than those who foraged during the day, the researchers found. Genetic tests of parasitized hives also showed that both bees and flies were often infected with deformed wing virus and a fungus called Nosema ceranae.

Some researchers have pointed to the virus and fungus as potential culprits in , and hive abandonment is the primary characteristic of the disorder. It may be time, Hafernik said, to consider how the fly parasite fits into the CCD picture.

He said the next step is to find out exactly how the parasite is affecting the bees' behavior. It is possible, he said, that the parasite is somehow interfering with the bees' "clock genes" that help them keep a normal day-night rhythm.

The researchers also don't know if the infected bees are leaving the hive of their own accord, or whether they give off some sort of chemical signal that provokes their hive mates into throwing them out. "A lot of touching and tasting goes on in a hive," Hafernik said, "and it's certainly possible that their co-workers are finding them and can tell that there's something wrong with them."

The scientists will deploy a range of tools -- from tiny radio tags to video monitoring -- to help them answer these questions and discover ways to protect the hives.

"We don't know the best way to stop parasitization, because one of the big things we're missing is where the flies are parasitizing the bees," Hafernik noted. "We assume it's while the bees are out foraging, because we don't see the flies hanging around the bee hives. But it's still a bit of a black hole in terms of where it's actually happening."

Genetic analysis of the parasites confirmed that they are the same flies that have been infecting bumblebees, raising the possibility that the fly is an emerging and potentially costly new threat to honey bees.

"Honey bees are among the best-studied insects in the world," Hafernik noted. "So at one level, we would expect that if this has been a long-term parasite of honey , we would have noticed."

Explore further: Male monkey filmed caring for dying mate (w/ Video)

More information: "A new threat to honey bees, the parasitic phorid fly Apocephalus borealis." PLoS ONE.

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5 / 5 (3) Jan 03, 2012
I have been reading about this for the past couple years, I hope they find a solution for this soon, as foretells some very bad things for food production if it keeps getting worse.
4 / 5 (2) Jan 03, 2012
I was wondering if there is a mechanism like cordeceps use, then I thought...

I wonder if anybody has tried working on GM cordyceps for this ?

Something that specifically targets A. borealis ?

not rated yet Jan 04, 2012
Perhaps more understanding of the life-cycle of A. borealis would help, Isaaacsname, because it could be that it can infect other bees while in the nest, if its life-cycle allows that. If that is the case, a minor re-design of industrial bee-hives would perhaps allow the bee "health officials" to be more efficient at keeping the thing out of the hive and reducing CCD. Current designs seem to be very open, allowing bees to come in and out unchecked. (I think the checking is mainly done by particular bees - the health officials - not just any old bee, who would stand at the entrance, if there was just one, that is.)
not rated yet Jan 04, 2012
Hhmm..good points,

I worked with some hives years ago when I was in school, something I thought about regarding this new parasitic wasp:

A common practice ( I don't know how common anymore ) used to be for beekeepers to shuttle hives from orchard to orchard for pollination of commercial operations, I have heard it was not uncommon sometimes for some hives to have spent a year in locations that stretch as far as halfway across the country, more in some cases, iow, the dispersal vector could actually be the people moving the hives from farm to farm across the continental states.

..I would be very curious to know whether they actually invade the hives looking for the bees.

There are ways...for ex..Varoa mites, ...we used a small paintbrush that laid a trace of menthol on the bees backs' when they left the super, something the guy I was studying under showed me, keep the mites off.

...definitely got my interest piqued.

not rated yet Jan 04, 2012
Hhmm..good points,

I worked with some hives years ago when I was in school, something I thought about regarding this new parasitic wasp:

A common practice ( I don't know how common anymore ) used to be for beekeepers to shuttle hives from orchard to orchard for pollination of commercial operations, I have heard it was not uncommon sometimes for some hives to have spent a year in locations that stretch as far as halfway across the country, more in some cases, iow, the dispersal vector could actually be the people moving the hives from farm to farm across the continental states.

Couldn't that be doing the parasites a big favour, if it means putting different hives in close contact with each other, giving parasites more chances to spread to new hives. Is that what you were getting at?
not rated yet Jan 04, 2012
Exactly. I just did some quick digging online, they still transport hives across the entire continental states.

>facepalm<...hard to believe.

I would think A.B. is a prime candidate for one of the " Sterile insect techniques ", GM or irradiated males.


5 / 5 (1) Jan 04, 2012
I could see this happening:

One or two bees get eggs laid in them, the hive gets sealed and transported for 7-10 days, while sealed, the infected bees cannot leave the hive, so there could be an ideal environment to have a population explosion of A.B., by the time the hives reach their new destination, the bees start cleaning the dead bees out of the hive. The problem there is that they don't take the debris they remove from a hive very far away from the hive, so they would be dumping the dead and/or infected bees in the vicinity of the hive.

Perfect conditions to perpetuate the cycle. Seems like the problem is 3-fold though, as A.B. carries other agents.
not rated yet Jan 04, 2012
I wonder if there is any relationship between these parasitic flies and the parasitic insects used in some forms of biological pest control.
not rated yet Jan 04, 2012
Isn't the Phorid Fly what some are using to combat Fire Ants? If the Phorid is not native to here then its introduction may enable it to prey on other species that don't have a defense against it.
not rated yet Jan 05, 2012
According to Wikipedia, phorid flies are genus Pseudacteon, whereas the bee parasites are Apocephalus. They are similar, but different. Specialisation in the insect world often prevents one from being able to do as the other, even though they seem very similar. I suspect that a phorid fly would not "know" what to do in a bee hive.
not rated yet Jan 06, 2012
... Also, the chances are that the Phorid flies would not produce the correct biochemicals to affect bees in the way that suited them.

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