"Norminn" wrote in message

stuff snipped

Pesticides and herbicides could impact them in a few ways, either by
direct chemical effect or by changing their food sources. With people
so anxious to kill everything that crawls in their yard, I'd be hard to
convince that chemicals don't have an impact.

From the USDA's Ag. Research Service:

Not all pesticide impact is about directly killing honey bees, however.
Sublethal doses of the pesticide imidacloprid-one of the neonicotinoid group
of pesticides-were found to make honey bees more susceptible to the gut
parasite Nosema, according to a study by Pettis and University of Maryland
researchers Dennis vanEngelsdorp, Josephine Johnson, and Galen Dively.

The researchers fed three generations of honey bee colonies either 5 or 20
parts per billion (ppb) of imidacloprid, which is used to protect a wide
variety of crops and ornamentals from many different insects. The dosages
used in the study were intentionally well below the levels that have been
documented to kill honey bees after short-term exposure and reflected levels
that have been measured in the environment.


After the third generation, newly emerged adult bees from these colonies
were exposed to spores of N. apis and N. ceranae, gut parasites that have
been a growing problem for U.S. beekeepers since the 1990s.


There was up to a fourfold increase in the levels of Nosema in honey bees
from the imidacloprid-exposed colonies, regardless of whether 5 or 20 ppb
were fed.

http://www.ars.usda.gov/is/AR/archiv...colony0712.htm

While historical records seem to imply the CCD has occurred in the past,
there's no way to determine the actual similarity to today's CCD problems
because back then no one had ever even heard of DNA.

It reminds me a little of thalidomide, a drug whose ability to cause birth
defects was strongly denied by 1,000's of doctors who had successfully
prescribed it to pregnant women without incident. Eventually it turned out
that the US, which had not approved the drug, had very few cases but
countries that had approved had many.

That eventually led to the discovery that a certain dosage level taken at a
critical time (I think 60th day) led to the formation of flippers instead of
arms and legs. That's why I think the EU ban will either make or break the
connection to neonicotinoids. If they experience far fewer CCD incidents
after the ban, then we'll finally have a real smoking gun even if we still
don't understand the mechanism.

I was surprised to see a report that implied that CCD might be related to
cell and cordless phone use. The media came to that result based on a small
German study that implied close-by radio signals can disrupt bee's
direction-finding capabilities. Needless to say, it was quickly disproved
since CCD occurs in places with virtually no EMI.

--

Bobby G.