This past week I was invited by Bayer CropScience to attend their global press conference in Monheim, Germany. One of the topics covered during my two-day stay was honey bees.

In general, we know that we need honey bees to pollinate crops. But here's a bit of perspective…

The total economic value of pollination worldwide is estimated at $197 billion in 2005, which represents 9.5 per cent of the value of the world agricultural production used for human food that year.

It is estimated that about 1/3 of all plants or plant products eaten by humans are directly or indirectly dependent on insect pollination.

Bee Numbers Up or Down?

Well, it all depends on where you are in the world. Overall, the global number of bee colonies increased by about 45 per cent over the last half century, but Europe and North America have seen a decline.

• Asia +426%
• Africa +130%
• South America +86%
• Oceania +39%
• Europe -26.5%
• North America -49.5%

The decline in North America and Europe has been due to a number of factors including parasites, diseases, extreme climatic and environmental factors and also agricultural and beekeeping practices. However, Klemens J. Krieger, Bayer CropScience project manager bee health, said it is widely recognized that the Varroa mite, an external parasite, is the key threat to honey bee health. The Varroa mite weakens honey bees, multiplies rapidly and transmits pathogenic viruses to honey bees.

"Experts agree that the Varroa mite is the main cause of honey bee losses," Klemens said. "The media coverage has captured all the theories topic of bee loss - one year it was cell phone radiation, the next a virus, the next it was pesticide use. Finally, experts say it is the Varroa plus "X", and it's believed that "X" is a virus that enters the honey bee through lesions left by the Varroa mites. So if you eliminate the Varroa, you also eliminate the virus."

Having seen a lot of the press that Klemens mentioned, I was a little hesitant to believe that the Varroa was to blame for bee losses. So I did a little more research to see what other experts were saying about the Varroa mite and honey bees.

Dr. Keith S. Delaplane, professor at the University of Georgia, said the recent connection between Varroa and a region-wide bee decline was so plain to one group of authors that they put it in the title of their paper: "Varroa destructor is the main culprit for the death and reduced populations of overwintered honey bee (Apis mellifera) colonies in Ontario, Canada."

Delaplane also echoed the summation of Peter Rosenkranz and co-authors when they said, "No other pathogen [beside Varroa] has had a comparable impact on both bee-keeping and honey bee research during the long history of apiculture."

Delaplace said, "It is simply non-controversial among the world's practicing bee scientists that Varroa destructor is problem #1."

In the US, North Carolina State University says the Varroa mite (Varroa destructor) is the most serious pest of honey bee colonies worldwide. Virtually all feral (or "wild") honey bee colonies have been wiped out by these mites, and beekeepers continue to struggle with Varroa infestations in their hives.

I came across many research papers and university and private company sites that said the same. So my skepticism has been appeased.

I would also like to say thanks to the Bayer CropScience team in the US and Germany for their hospitality. Ninety members of the press from 20+ countries attended the press conference last Thursday. If you'd like to read more about the press conference, click here.

Have a great week!