I am with you Peter (and the german researchers) that winter mortality is
due to virus / varroa and probably not due to nosema alone. But Nosema
control is not only for avoiding winter mortality, it is more for increasing
production during summer flows, and probably avoid the spread of any virus
asociated with it. As said on another post N.apis had its how associated
viruses (BQCV / virus Y). Why not N.ceranae?

In that sense I think this thread (right dose of fumagilin) had to be link
with your worries about between-flows control of varroa with formic or
thymol.

We have been too worried about honey quality and honey quantity, without
taking serious considerations of any pattern change in honey flows due to
climate change (I must declare that I am an skeptic on human sole
responsability), but clearly there had been a change in weather pattern in
the past decade.

At least in Chile we have observed in the past 6 years a constant delay in
the honey flows. Our "long and narrow strip" allows us to have a 9 month
long season if we move our colonies from  north to south. With this
possibility we end up having more than one queen/brood laying season in the
calendar season.

If we go for the honey quality and quantity (this latter not always an
objective we can accomplish) we end up loading our colonies with varroa,
that we can not control to protect honey quality.

At the end we experience high winter mortalities, why?. Too much varroa, too
much viruses, "old" queens and I am afraid, nosema and its own associated
viruses.

For the past two seasons I have changed a bit my manangment, first including
formic acid application "within a honey flow". I believe formic is the less
damaging varroicide of the organic ones available in terms of honey quality.
At the same time, we make a nuc for each colony that will go to our late
Ulmo honey flow. With this nuc we can change the queen and reinforce the
dimished colony that comes out of that autum flow, a killer flow. We also
feed the productive colonies with close to two kg of pollen supplement with
in the honey flow prior to Ulmo (Tiaca). The aim of this feeding is to
increase colony population for it to stand the rigors of this late flow.

But we do not have at the moment any means to control nosema or  viruses.

I firmly believe that the addition of an essential oil (like carvacrol) in
those patties will make the difference on our chilean migrating conditions.
We need to  be able to control varroa and nosema at the same time prior to
our late honey flow, to have colonies that not only give us some honey, but
survive in good shape the winter for been rented for pollination next
spring.



-- 
Juanse Barros J.
APIZUR S.A.
Carrera 695
Gorbea - CHILE
+56-45-271693
08-3613310
http://apiaraucania.blogspot.com/
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