The varroa shaker does not extract 100% of the mites. Two weeks ago we
compared it to icing sugar.  icing sugar extracted about 45% of mites and
the varroa shaker extracted 90% if the mites. We developed the regression
line based on 1650 samples. It is published in ABJ. Based on the reg line,
we add 2 mites to every reading that we get after the shake to stay within
95% of the real reading. To be more accurate you can use the equation. When
mite levels are too high extraction of mites is less. The same applies when
number of bees are larger than 3oo.
At least we have a simple method for beekeepers to determine  what is their
mite level. Based on the level using the varroa shaker we developed the
treatment threshold for Albertans.  Thus, beekeepers can compare oranges to
oranges with a certain degree of acceptable reliability. Glad to report our
beekeepers finally are monitoring their mites and using this info in making
decisions. The other day, one of my beekeeper did not treat  varroa for 18
months after using Apivar in spring 2009. This fall he is using Apivar. If
he did not use the shaker he would have used Apivar in fall 2009 and spring
2010. His winter kill is less than10% in this time and age. These results
can be reported in many operations across Alberta. This is a progress but
media does not like to hear this.
If there is bad news it travels fast.

Medhat

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