Why Are Bees Dying?

As bees disappear at an alarming rate, scientists are scrambling to understand why. Earlier this month, the U.S. Department of Agriculture awarded a $4 million dollar grant to scientists at universities across the country to do just that. The leader of that team, entomologist Keith Delaplane at the University of Georgia, spoke with Newsweek's Kate Dailey about what might be causing the bee collapse, how it can be stopped and the potential impact on the Western diet. Excerpts:

NEWSWEEK: Where are the bees going?
Keith Delaplane: We've been tracking a decline in the number of beehives since 1940s. What has caught everyone's attention is a spike in that trend beginning in 2006. You'll have a hive full of bees but its population just, without explanation, dwindles away. There are increased rates of colony mortality, there are increased rates of queen death, and when your queen dies the whole colony falls down pretty fast. The whole effect has been a decline in the number of beehives. They're just more difficult to keep alive.

How do you determine the cause of death?
We can take a look at dead bees and we can eliminate some things. We can find some parasites and other diseases on them, so we're not totally in the dark.

Is there a singular cause felling the bees, or is it a perfect storm of factors?
There are a lot of factors conspiring against honeybees. They include exotic parasites and pathogens, pesticide use in the environment, declining forage crops [such as alfalfa and clover]-all of these things play into it.

You've just received a grant to try and figure this out. What's the first step?
When you think about it, it's a formidable job. You have to take a big long list of suspected agents and you have to tease them out and test them individually, and then you have to test them in combination. There are viruses, and there's a single celled organism called microsporidium. We think that they are possibly interacting, so if you have a colony with both of them, it's kind of a double whammy. We also have parasitic mites that have been introduced in this country. So the question now is which of these suspected culprits, and what combination of these suspected culprits, is the chief cause?

Where are these viruses coming from?
Honeybees have had these viruses from posterity, as far as we know. What does seem to be new is a particular parasitic mite, the varroa mite. It's like a bee tick: it gets on their body and sucks their blood. It is a native parasite of another species of honeybee from Asia, and in the 1980s it was introduced into North America. And ever since then we have seen a surge in the virulence of all the ordinary viruses. Does the varroa mite vector [carry] them? Does it activate them? Does it aggravate them? We don't really know the answer to that. But it does seem that varroa has made these old viruses more virulent.