Hi all

Peter said...
> Most of us do not,
> unsurprisingly, have a stock of liquid nitrogen!

Dry ice is not a good material for such testing.

Liquid Nitrogen was chosen because of the low temperature, this enables a
steep enough temperature gradient to be set up, that in turn is able to
extract the heat within the brood and ensure a kill.

The quantity of Liquid Nitrogen is also important... If the amount of LN is
too small it will all boil off before adequate heat has been extracted and
so there is a possibility of incomplete killing.

Liquid Nitrogen may not be available 'off the shelf', but is the 'right'
material for the job, it is also the quickest method and is least labour
intensive. There are breeding groups in UK that have gone to the trouble of
obtaining the Dewar flasks and supplies of LN.

An alternative for hobby beekeepers is to cut a square chunk of sealed
brood, transport to a domestic freezer, freeze and return to the comb, this
is as near as you will get to a simpler method, but it takes time and effort
and is possibly not as reliable as the standardised LN method.


Regards & best 73s, Dave Cushman, G8MZY
http://website.lineone.net/~dave.cushman or http://www.dave-cushman.net
Lash up machine

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