>Blane White wrote
>>As for the lower populations in mating nucs that is what I
>>would expect based on the biology involved i.e. these are small
>>colonies that never raised much brood and had frequent breaks in
>>broodrearing. Under these conditions varroa populations are unable
>>to build up quickly due to the breaks in broodrearing and may even
>>decline.  I would expect the varroa populations to be considerably
>>lower in the nucs than in full sized colonies in the same location.

>Here is a classic. Drawing 'conclusions' without all the facts. Our
>baby nucs have no breaks in brood, well perhaps a couple of days at
>most. We work very hard with the logistics problem of keeping them
>full and in brood all the time, as soon as a queen is ready to be
>harvested a cell is ready to refill it.

I've been waiting for Blane to reply, since the second writer did not seem
to understand his comments, but he made his point and left it at that.  I
think it bears a little more detailed explanation:

Mating nucs typically -- by their very nature -- have breaks in egg laying
of a week or more every two week (minimum)cycle.  This starts with a
minimum one week waiting period until the queen from the first cell lays
eggs.  Then eggs are only laid for a few days to ensure the queen is
laying, to wait for the slower ones to be mated, to ensure some replacement
bees in the nuc, and then the queen is snatched away and replaced with a
cell again.

In my experience -- which is limited since we only ran a few hundred baby
nucs for a season or two -- it is about 11 days in fact from cell insertion
before one can be reasonably sure of seeing eggs in the best case.  So,
when I say a week without eggs at a time in my observations above, I am
erring on the generous side.  If the nuc cycle is 14 days, as it can be in
good weather, then actually eggs are only being laid in each nuc for a few
days every two weeks.  In bad weather, often the cycle must extend to three
weeks, and then the period without open brood is almost double.

That in turn means that there are only cells being sealed for about 3 to 5
days out of each two week (minimum) cycle, and that is the only opportunity
that the mites have to get into cells to hide and reproduce.  All the rest
of the time, including that long initial period, the mites are forced to
live on the adult bees where they are most vulnerable to oil treatment,
falling off, discovery by the bees, or natural death.

Normally, in a hive with brood in all stages, adult varroa mites only spend
a few days outside sealed brood cells on adult bees -- after their first
emergence -- before entering their first new cell to lay eggs.  Thereafter,
they normally enter cells that are ready for sealing as quickly as they can
find them after each emergence, without spending much time outside the
safety of the cell.

Thus it is clear that in a hive which only offers the occasion brief
pportunity to enter cells, the varroa are forced to remain phoretic *much,
much* more of the time that they would in a hive that has continuous egg
laying, and that the mites are much more vulnerable.

Now, I don't think anyone disputes that FGMO kills mites pretty much on
contact under the right conditions.  The dispute has always been whether
the oil can be applied in a way that guarantees killing a sufficient number
of mites -- with good reliability -- without killing or damaging the bees
or causing other problems like diluting beeswax, etc.  To date, with the
methods of application so far tested, FGMO, has seemed to be product that
appeared to work very well in some cases, but did not perform much at all
in others.

It seems obvious, from David's clear observations which he shared with us,
that *something* set back the mites in his nucs quite significantly.  It
would have been interesting to have had a few nucs left untreated and
carefully observed, and maybe David will do so this year, but it is not
unreasonable to assume that at least two factors were at work here.  Which
one accounted for the decline of the mites is not proven.  Possibly it was
both, or possibly the interruptions in brood rearing set up the ideal
conditions for the oil to work very well.

What I get out of this is that FGMO *may* indeed be an ideal control agent
for mating nucs, and that more testing is warranted.

In order to understand better, I would like to know if varroa is *normally*
a problem in untreated mating nucs, or if they cannot hold their own and
are not normally treated by queen breeders.  We do know that mating nucs
must be kept free of v-mites, as must the cell builders, since varroa *can*
parasitize queens as both pupae and adults.

allen

As Andy signed his articles:

> (w)OPINIONS are not necessarily facts. USE  AT OWN RISK!