The points that Allen and John Harbo make match my casual observations in
several top bar hives this past season.  I had four TBH's running this past
summer, all with (supposedly) hygienic queens.  Towards the end of the
season (their first and only), all four were showing serious mite loads
(phoretic mites visible on many workers) and attendant symptoms (k-wing,
shriveled wings, crawlers, loss of vigor, etc.).  Since no foundation was
used beyond the initial four frame nucs installed into the TBH's, the bulk
of brood rearing was 'au natural' - totally on bee-drawn comb, and very
"droney".  The differences in drone populations in the TBH's compared to
Langstroths was quite noticeable - I'd estimate 3 times that found in a
Langstroth on foundation.

After looking at the varroa population curves at the URL in Allen's post, it
became obvious that the drones in my TBH's really were the primary issue.
For every 5% increase in drone populations, mite loads increase an average
of 50%. (!!!)  Based on my observations, and the varroa/drone connections
shown in the model, it would seem that controlling drone levels within a
hive would have profound effect on varroa levels - all else being equal.

It would also seem that culling any old, droney comb would be extremely
advisable, given the effect drone populations have on varroa levels.


Some wonderings aloud:

1 ) Does anyone know if any breeders have focused on lowering drone
percentages (and can it be done by breeding)?

2)  Similarly, I wonder if part of the success attributed to small cell
(4.9, etc.) could be lowered drone populations as well as smaller drone
size?

3)  Has anyone had any measurable success in varroa control by using the
drone foundation/freezer method exclusively?

Regards,

Todd.

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