If you read further into the paper, the authors describe the  
preparation of the propolis ethanol extract (PEE). Aside from the  
funny acronym, extracting with ethanol or methanol and drying it down  
to remove the alcohol is how most natural products research begins.  
It looks like the final concentration of ethanol is 10%. I don't know  
how that concentration may affect bees, but in typical cell culture  
(more sensitive), you want to keep the ethanol concentration below  
0.1%. I only scanned the paper quickly, but I did not see any mention  
of negative controls (treatment with 10% ethanol) for comparison.

from the paper:
2.2. Preparation of PEE
A concentrated propolis solution was prepared homogenizing 400 g of  
propolis in 1 l of ethanol 96%, and incubated for 10 days at 22–25 ° 
C. Then, it was filtered through paper filter and incubated until  
ethanol evaporated and the product obtained a honey-like consistence.  
This extract was diluted in ethanol 96% to a final concentration of  
10% of the extract to form the PEE (starting solution).

cheers,
Kurt


On Sep 8, 2008, at 12:00 AM, BEE-L automatic digest system wrote:

> Propolis itself was NOT tested!
>
> The paper addresses the use of a substance
> called an "ethanol extract of propolis"
> rather than propolis, so it should be clear
> that there is quite a bit of ethanol in the
> mix applied to the cultured AFB.


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