Randy
 
I've been analyzing for pesticides in beehives as well as urban, industrial, and military contaminants in bees, bee products, and wax comb since 1973.  


Any comb reported as not having at least a trace of at least one detectable pesticide is rare - some parts of MT are one of the few places where that has been true.


I used to say, if your lab can't find any detectable pesticides, find another lab.  But in recent years, we have seen samples with no detectable pesticides - although this occurs in rather isolated areas like some parts of western MT.
 
In the corn belt of the US and the Canola fields of Canada, we found that the diversity of detectable pesticides ranged from a single type of pesticide most commonly seen in bee colonies to about five pesticides in bees and pollen.  
 
As a general finding, pesticide diversity increases in colonies in more urbanized areas, especially  where there are lots of small farms, truck gardens, and summer homes with extensive landscaping and flower gardens.  Also, as we found as far back as the 80s, in affluent neighborhoods, beehives contain higher and more diverse pesticide residues than poorer neighborhoods - which we traced to the contract lawn services.  


As an old entomologist friend of mine who decided to open a pest control business in a wealthy community in Arizona - Rich folks got bugs, and poor folks got bugs, but only the rich folks will pay you to get rid of the bugs.


Finding multiple types of pesticides in beehives has been true since we started looking at pesticides in the 70s - the difference is the types of pesticides seen currently, versus the types of pesticides found 1, 2, or 3 decades ago.  Each decade seems to have its own common suite of pesticides - depending on marketing, usage, and development of new pesticide products.
 
Years ago, when farmers used many of the more persistent pesticides, all comb from all parts of the US that we collected had measurable levels of one or more of the chlorinated pesticides.  The ban on DDT resolved that, but it took over 20 years for this to disappear from comb samples - we were still picking the DDT, DDE, DDE residues up on the east coast in 2000.  By 2010 we finally saw the DDT complex more or less disappear from beehives (although I imagine one can still find it in localized areas of the US).
 
The other good news is that for the older 'classic' pesticides, measured in hive residue levels in ppms were not uncommon.  Today, when labs like Gastonia can screen for over 200 different pesticides in one analysis with ppb limits of detection, we seldom see ppm levels.  The majority of detections are below 100 ppb, mostly below 50 ppb, with levels of 1-2, up to 4 ppb of commonly used chemicals fairly typical.
 
So, types of chemicals found have changed with the decades, and levels seen have also changed.
 
In other work we've done, we have found that whole colonies of honey bees are much harder to kill with neonics then we would have ever imagined.  We often have to dose at levels well above the NOAEL in order to induce a measurable kill.


             ***********************************************
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