>Would you accept circumstantial evidence?

Circumstantial evidence certainly suggests suspected factors that should be
investigated.

One thing that helps us here is that although Apis mellifera is the common
"victim," the presence of the  factors suspected as being "the cause" for
elevated colony mortality vary greatly from continent to continent, from
location to location (such as exposure to ag chemicals only in ag
settings), and even by individual management (does one treat with
particular synthetic miticides).

This fact allows us to look for suspects that are common to all localities,
or absent from some.  What we'd especially be interested in are changes in
the presence of the suspect around 2004, at which time we started to notice
elevated colony loss rates.

There was widespread failure of currently used miticides during that time
period, and varroa frequently got out of hand.

There appears also for there to be a trend in which the mite-vectored
viruses also evolved into more virulent forms, although this timing varies
from country to country.

Nosema ceranae also circumstantially invaded most continents concurrent
with elevated colony losses,  and would be on my list of major suspects.

A number of countries are also experiencing epidemics of new forms of EFB
or EFB-like brood disease, also occurring in the same time frame (this was
strongly associated with my major collapses in 2005/2006).

Other concurrent changes are climate change, major changes in agricultural
practices (a shift towards more maize and fewer hedgerows), virus evolution
due to the presence of the vector varroa, and changes in miticide use.

Coumaphos contamination is a common factor in many countries, as is the use
of amitraz (which in the U.S. generally correlates with the advent of
increased winter mortality).

In the U.S., tylosin was approved for use in the fall of 2005.  But since
it is not used in some other countries, we can likely eliminate it as the
cause.

As far as the neonics, the timing of neonic use is common in ag localities
in most countries, but varroa is not present in Australia.  So we can check
to see whether colonies exposed to neonics in Australia crash as is claimed
for those in France.

And then there are the introductions of other pesticides at about the same
time as the neonics, which most everyone is ignoring.  For example, go to
the USGS maps of pesticide application over the
years:http://water.usgs.gov/nawqa/pnsp/usage/maps/compound_listing.php.
Click on pyraclostrobin (a fungicide).  Then click on the maps from 2000 to
2009.  You may note that its use in the U.S. also closely coincides with
elevated colony mortality, which began about 2004.  I'm not saying that
pyraclostrobin causes elevated colony loss, but just that if one is going
to look for circumstantial evidence, one should investigate ALL suspects,
not just your favorite.

-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html