From Allen:

* but marginally adequate for tracheal at the 2% level at
  the level of testing we have done so far on the samples
  collected (20 actually tested out of 175 collected)

From me:
Did I read the first posting wrong?  I thought you had collected five
samples from all hives in ten yards, with an average of 35 hives per yard =
1750 samples, not 175.  Have I misunderstood?  If so, then by the poisson
method you can only be confident with 95% certainty that your infection rate
is one in 58 or fewer, which is not really all that good.  In a hive of 30000 bees you can have up to 520 varroa mites and nosema spores, on average.  If you tested only 20 for tracheal mites, then at the 95% level of confidence chances are that about one in every seven bees has tracheal mites, or at least that is the highest infection rate that you could have missed.

I am not yet a practising beekeeper, so I don't know if an infection rate of
1.76% (Nosema and varroa) is high enough to treat - though to me it suggests more intensive sampling is warranted - but I imagine that a rate of 14% (tracheal mites) is.


Martin Damus