>
> >Does exist an established economic threshold for nosema spore counts?
>

David, this is a very hot topic among nosema researchers, and as Juanse
says, there is no agreed upon figure.  Nor is there an agreed upon sampling
method.  There is active communication among nosema researchers about this
topic, since everyone wants a published figure to use.


> >Does anyone know a scientific paper or research about this topic?
>

Check my articles for published references.  Recent research suggests that
even low levels of infection may have a negative effect upon colony health.
 But depends largely upon colony nutrition, and vigor of the queen, as bees
can "outrun" nosema if they can recruit enough new population through
broodrearing.

>
> >E. Mussen also states on newsletter: “If infection levels are below
> 10.000 spores per bee, no spores will be seen over the entire grid…”  Could
> anyone help me showing where this detection level appears (scientific
> paper, article…)?
>
> David, it's simple math.  Hemacytometer count is simply the average count
per tiny square x 4 million.  You typically count 80 squares.  So one
single spore found among the 80 squares would give an average count of
50,000 spores per bee.  Thus, you'd be unlikely to find even a single spore
if infection level were only 10,000 spores.

However, if you use the individual gut squash method, then you can easily
find weaker infections.

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

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