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 combination of increased mite infestation, virus infection
and bacteria is the cause of the two-week death collapse of hives."

The mites suppressed other immune responses in the bees, leaving the
bees and the colonies more vulnerable to infection. The bee mites
transfer from adult bees to late stage larva. The virus can be
transferred through many different pathways.

"This system is important not only because of what the mites are doing
to honey bee populations in the U.S., but because it can be used as a
model system for exploring what happens to viruses in animal or human
populations," says Cox-Foster. "If we view the colony as a city, then
we have a variety of infection modes -- queen to eggs, workers to food
supply, bee to bee, and parasite to bee."

-- 
Peter L Borst
Danby, NY USA
42.35, -76.50
http://picasaweb.google.com/peterlborst

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