"A group of Japanese researchers found that a virus that is 99 percent the same as deformed wing, appears in in the brains of aggressive guard bees," says Cox-Foster. "Guard bees that are aggressive better protect the hive, so there may be some positive effect in this virus that allows it to persist in a colony."
The combination of bee mite infestation and deformed wing virus does cause deformed wings in about a quarter of the emerging bees. This, however, does not lead to sudden hive collapse. Something else is involved that makes bee mites so harmful to bee colonies.
The Penn State researchers report their findings in today's (May 17) online version of the Proceedings of the National Academy of Science.
Yang and Cox-Foster looked at how bee mites affect the bee immune system. They injected heat-killed E. coli bacteria into virus-infected bees that were either infested with bee mites or mite free. The dead bacteria was used to trigger an immune response in the bees in the same way human vaccines cause our bodies to produce an immune response. They checked the bees for production of chemicals that disinfect the honey and for other immunity related chemicals.
They also measured the amount of virus in each bee. Surprisingly, they found that the virus in mite-infested bees rapidly increased to extremely high levels when the bee was exposed to the bacteria. The virus levels in mite-free bees did not change when the bee was injected with bacteria.
One chemical, GOX or glucose oxidase, is put into the honey by worker bees and sterilizes the honey and all their food. If bees have mites, their production of GOX decreases.
"As mites build up, we suspect that not as much GOX is found in the honey and the honey has more bacteria," says Cox-Foster. "It is likely that the combin