>What is the accuracy of the VHS?

The VHS washes off over 95% of the mites when the total mites in the 
sample is less than 25 mites/ 300 bees. As mite numbers increase, mites 
tend to hang on bees. When we washed all of samples with various mite 
levels, we still got excellent correlation with washing samples for 15 
minutes using an orbit shaker then wash bees with water to separate mites 
from bees. Check American Bee Journal for a published abstract in May 2010 
issue.
I would care for accurate measurements at lower mite loads. If you are 
using 3% as an economic threshold (ET), counting 7 mites/300 bees means 
3%. This figure includes the correction factor. In Alberta we use 3% as 
ET. We recommend to collect about 1 inch of bees from brood combs. The 
number of bees in 1" ranged from 250-350 bees. If you testing several 
hives, the number averages to 300 bees. This is a tool for a quantitative 
testing of mite prevalence. If it is used consistently, you will be able 
to compare numbers. It only takes 50 sec to shake. Alberta beekeepers 
liked the idea. They carry this VHS jar in their inspection kit. 
Therefore, we are moving aggressively to implement IPM based on real 
numbers. Overall , the VHS would give good results up to 10-15% mite 
infestation. About 15%, it will give underestimated numbers due to leaving 
mites with bees.
 
I did not test powdered sugar. However, I learned yesterday in Vancouver 
Island, where I gave a talk on IPM that using powdered sugar in this jar 
did not give good results. the recovery of mites was variable and low. 

Yes the materials cost $2.

Medhat

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