On Tue, 2006-10-31 at 19:47 -0500, J. Waggle wrote:
> Now you have a tool that can help identify desired traits, and may help in
> the selection process, instead of a bunch of numbers and slapping in
> treatments.
My colleague Rodger Dewurst, a co-founder with me of the Cornwall Bee
Improvement and Bee Breeders Group, has been doing this for a couple of
seasons now and has presented his findings to SICAMM Conference in
Versailles and our work together in BKQ. He has shown that you can
select these different behaviours for a breeding programme relying on
open mating (our bees do Apiary Vicinity Mating in poorer weather) and
improve the stock steadily. I have observed the chewing increase
dramatically after selection in both magnitude in individual colonies
and across an increased number of colonies. He has been selecting for
bees that bite the beekeeper by tugging at his skin (I have seen this
too increase using a different selection scheme) and finds that the
amount of grooming and damage to mites increases in the subsequent
generations. He has separated out the damage to mature adult, immature
adult, and immature young mites of all ages and found differences
between colonies and the proportions of the different aged mites damaged
between colonies. He has also been using a "compression test", before
and after removing supers, compressing the colony down to the (usually)
single brood chamber and in some colonies this increases the damage rate
to above the 60% figure Wallner found led to varroa tolerance. He argues
that our weather patterns here in West Cornwall will often produce
"compression" which may account for intermittent increases in damage,
but also night will increase congestion and the likelihood of grooming.
He has also observed, as have many on this list, social grooming dances
and auto-grooming, where a bee removes a mite itself from its back using
its hind legs and others then take the mite away after a "shiver dance".
Like others, I believe the chewing, which is first observable in a
"pepperpot pattern" of brood in the spring, is an attempt by the bees to
get at varroa in a pupa which is showing the adults that it is
distressed but cannot get to it without removing the pupa bit by bit.
The evidence on the varroa tray shows antennae, legs and pupal cases as
well as bits of body. This can, as Joe said, be correlated with the
brood comb as long as you look at the tray and note where the evidence
lies. In some cases, you see clusters of pupal bits and immature young
mites, up to the stage you expect at the purple eye stage (around when
the chewing takes place) but no immature adults, only mature ones. This
implies the action is taking place in the chewed out cells and not as
the bees emerge when you see the chewing out in progress or empty cells
immediately above the debris.
We argue that the bees' defence against small invaders is their
mandibles, which I believe have 2 main components: the tips, which cause
indents in the varroa's carapace and the sides. which have a scissor
like action, sometimes cutting right through the mite. In 2001 I posted
a question about bees biting the beekeeper and Aaron and Mike replied,
but no-one said they bred bees with this character. Rodger has been
doing this since soon after we found varroa in our bees in around 1996
and it is a great surprise to visitors, many of whom normally use gloves
to inspect hives. Additionally, the hygienic behaviour, which includes
removing adult bees as they emerge, attacking and removing wax moth
larvae, bee larvae and pupae, chalk brood and so on, is much more easily
observed with no smoke or very little. In the UK, we tend not to replace
queens in the spring so we rely on 7-10 day inspections to deal with
potential swarming and can observe such behaviour and patterns of mite
fall and related debris on the tray. Incidentally, Rodger deals with
nest expansion by removing sealed brood to above the queen excluder and
replacing the comb with foundation both to assist the rate of laying and
the total population of bees, and maintain clean comb, which makes
observations on the tray much easier as it reduces other debris. A bit
more intensive than using a second box, but it works for him, given his
interest in the measurements he is making.
As you say, work in progress. I shall be amending the page below with
some of Rodger's pictures which he was holding back for the published
papers.
My thanks to all who have reported on chewing pupae in the past. It
became starkly apparent this season.
james kilty
http://www.kilty.demon.co.uk/beekeeping/improvement.htm
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