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Thu, 7 Mar 2002 10:13:58 -0500 |
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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
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