On 6 August, Todd introduced : "the supressive effects of broodless periods
on varroa populations.  ....I wonder if a usable, chemical free varroa
management plan could be built around this concept, without sacrificing too
much production?"

May I venture that there is an effect, yes,  but it can only be only
suppressive, and therefore insufficient on its own as a  control measure.  I
surmise (yes, surmise) that noone would want to cage the queen before the
'critical date' - the day after which there is insufficient time for the bee
to become a forager - say 1 June in UK. Caging the queen then means all
sealed brood would hatch by 3rd week July - and all varooa would then be
riding on bees. It is likely two things both then happen - (1) an increase
in any tendency within the colony to groom, as the opportunity to groom
would increase in proportion  ...   plus increase in the number of varooa
that simply lose their hold and fall to the floor if that can be assumed
also to be simply in proportion to the number of 'riders'. PROVIDED that the
hive has a mesh floor,  and any tray is at least 2 inches below the mesh,
those failed jockeys never return.  (2) loss of varooa attached to foragers
that die in the fields. There do not seem to be many published charts of the
variation in colony size thruout the year - I tend to use the 6 charts given
by E P Jeffree in a lecture to the UK Central Association of Beekeepers in
1959.  They mostly show colonies peaking around end June, followed by a
steep drop of up to 25% by end July. So we could expect some 25% of varooa
to be lost in action, unless varooa are particularly good at selecting the
younger and luckier mounts.    Adding the two effects - for a break in egg
laying of say 3 weeks - might bring down varooa by what, say 50%?  Or is
there another mechanism I have overlooked?

For that reduction, the colony will pay a penalty from reduction of nurse
bees during July.  That may be important since less brood rearing in July
will lead on to a shortage of nurses in August / September when rearing of
winter bees should get going.  So there must be some risk of weakening the
colony.

A way to use the principle of a brood break into a viable control measure is
(I suggest) to positively attack the varooa while there is no sealed brood,
rather than rely on natural decline.  There are so many ways when varooa are
exposed - especially if the hive has a mesh floor and so varooa need only be
shocked so they lose their grip, not killed outright.  Combs can be sprayed
for example with perhaps sucrose octanote esters, or simply puffed with talc
or icing sugar. One I have up my sleeve for resistant mites is to puff
tobacco smaoke upwards thru the mesh floor, with the supers off and the
brood covered temporaily with just a mesh screen, so that the smoke can blow
thru for a few minutes but the bees not take off - no need to handle the
combs unless it is preferred to take out the queen for safety.

That leaves just the problem that a complete brood break may leave the
colony short of nurses.  The method I use is to divide the colony at its
brood peak into a broodless swarm (with the queen) and the brood plus
nurses.  If there are no queencells at the time, the two parts are left in
contact for a week, by when 'sueprcedure cells' will have been started in
the brood  - if there are cells, the two are completely separated straight
away.  The (broodless) swarm can then be treated for varooa - at present,
still with strips - and the queen keeps laying.  Three weeks later the brood
in the other half has all emerged so that can be treated.  That part will
also have produced a new queen - which can be substitued for the old queen
when the two parts are re-united, so solving swarming for the rest of the
season.   I feel this is a good example of 'Integrated Pest Management' -
evolving new routines that manage both the colony and pests at the same
time.

The difficulty is of course the labour invoved if the colony is kept in a
conventional tired hive with the swarm being kept on the floor and the old
brood placed at the top of the pile - you have to keep lifting off all the
supers to get at the lower brood nest.  The method becomes much easier using
a double length box in which the two parts are kept at the same level,
separated temporaily by a solid vertical divider.  Yes, it is a new pattern
of hive - but not original - even so, of no interest to those who feel
beekeeping reached perfection with Root's Simplicity hive  (virtually the
modern Langstoth) around the year 1890.  But it is an alternative for
beekeepers who want to solve swarming and varooa control and also reduce the
sheer labour of handling heavy supers so often.  (My supers are also made
half width, to take 5 wide-spaced Manley frames - reducing the maxximum
weight to 16 pounds.)  Other examples of double-length  hives are of course
L L Langstroth's own twin hives illusted in the frontispiece to the 1977
facsilile edition of Langstroth's Hive and the Honeybee, 1853 - inside
Langstroth says his twin hives were the best.  A more recent double-length
supered hive is shown in BeeSource.com/EOB/Urban Bee Condo/Long Hive, but I
do not know details of that.  My own pattern of supered double- length hive
for deep brood frames (Dartington Long Deep Hive) is now being tried by a
number of UK beekeepers, each batch made in Eastern Europe being sold out
quickly - so there may (or may not) be independent verification of the
method at some time soon .

So yes, it may well be possible to establish a cjhemical-free method for
varooa control that starts with the principle of a broodless period.

Robin Dartington

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