> Railway       3            47               50             High
> Jahns         2            48               50             Medium
> Meglis        10           40               50             Medium & Low
> Falks         6            44               50             Medium
> Kievers       1            49               50             Low
> Dixons        4            46               50             Low

Continuing to reply to my own replies...

Revealed in this table is another reason that tracheal testing is not as
simple as testing for varroa (not that testing and interpreting tests for
varroa are simple).

Varroa testing for the most part is simply a matter of counting mites that
fall off a specific number of adult bees when washed in alcohol or found on
100 pupae. (There are more subtle measures, such as used in SMR evaluation,
but that is beyond our present scope).

Tracheal infestations, however, have numerous confounding aspects: one
aspect, considered a primary one, is the percent of bees in a hive carrying
mites, another is the number of trachea infested in such bees, a third is
the number of mites (total) per bee, and I suppose a fourth is the age of
the infestation in the bees (eggs or adults).  Another consideration is
whether the mites are actually alive or dead, since dead mites remain in a
bee until it dies, even if the bee was treated with menthol or formic.

The strain of bees under consideration will affect the mix of the above
factors observed and also their significance.  Some strains of bees, for
whatever reason, carry lower mite loads and some of those can suppress mites
to very low levels.  Other strains cannot and can get extremely high mite
infestations.  Given the mix of sub-families in a hive, individual bees in a
hive may vary widely in their susceptibility to carrying mites, and that can
be reflected in some hives having a mite or two per bee while others have
many mites per bee, and other hives having bees with many mites along side
sister bees with low or zero loads.

In the above example Railway has 6% of the bees with at least one mite, and
the lab has indicated that each tested bee had on average a 'high'
infestation.  That would be several trachea with several mites each.  Dixons
has 8% of the tested bees with fewer trachea with fewer mites affected.

If I had to guess, I would assume that the yard with a higher percent of
bees with more mites in more trachea of these bees would be more at risk,
but as I said, in this case we could see no losses that were obviously due
to TM.

In view of these ruminations, it seems to me that having examined as many
bees as we did, not finding one mite is reassuring.

allen