From: "Peter Edwards"  " Robin Dartington said: When all else fails, we will
have dusts and powders ...fine dusts can  probably still  help when varooa
has become resistant to all other chemicals in use  today."

I hope it was clear I was quoting Bernard Mobus, The Varroa Handbook, 1988 -
not making my own statement.
Peter questioned possible contamination of honey - a good point. MAFF
leaflet 1996 includes under  'commonly used biotechnical methods'   'fine
powder , normally talcum powder or icing sugar, dusted over all bees but
avoiding open brood...harmless to bees'
Mobus reviewed all measures being used in 1988. Dusts were then regarded as
'most promising'. France had reported  100% success with powdered glucose -
but sugar powders could kill open brood.   Pollen substitutes \ powdered
pollen were also used - which presumably minimises risks to brood and
contamination of honey.
The disadvantage of dusts then was the labour involved.  But we seem to be
entering more laborious times, so I am hoping these dusts are OK in
practice - but would very much like to hear from anyone who has been using
them, since the Mobus info is a bit old.
Mobus did say that simple chemicals such as formic were least likely to
generate resistance, as Peter points out, but apparently organisms do
develop resistance when a single chemical is applied over a long time.
Where dusts are interesting IMHO
is that they may be useful in programmes to identify colonies that are on
tghe way to developing a grooming habit - whereas using chemicals of any
sort surely just ignores those trends?

Robin Dartington

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