> Pete, I'm not sure that Marla's hygienic behavior is the same as VSH.  She
> and I have discussed.  The bees sense decaying brood in the first, the
> presence of a mite egg in the second.

But I used the term "hygienic behavior" more broadly than that (she
doesn't have a trademark on it!) to include an array of mechanisms as
opposed to an immunological defense, which honey bees seem to rely on
secondarily.

>  It should be noted that no single resistance mechanism is considered to be responsible for the varroa tolerance of honeybee populations in Russia, Arizona and Kentucky. Rather, an amalgam of many different traits both behavioural and physiological is considered to be responsible for the tolerance. In the mite tolerance in African bees, this smorgasbord of tolerance-inducing characteristics appears not to be the case. The direct aggression of African honeybees to varroa mites, the presence of a natural biocontrol agent, and the attractivity of brood to mites could all be excluded as possible causes of tolerance, leaving only hygienic behaviour and the short post-capping period of Cape honeybees as the cause of mite tolerance. These are, however, considered sufficient to explain the in-hive development of mite tolerance in African bees.

> The only essential characteristic necessary to explain the tolerance is the ability of honeybee workers to detect and remove reproducing mites, and to leave non-reproducing mites. This hygienic response is well developed in African and Africanized bees, and is highly heritable. The seemingly continent-wide tolerance of African bees to American Foulbrood suggests that hygienic behaviour may be very well developed in African bees and will lead to the percentage of reproducing mites in a colony being systematically reduced, without the colony succumbing to the mites. (Allsopp 2006)

> Our honey bees (Apis mellifera) have few natural defenses against the Varroa mite. Their original host, the Asian honey bees (Apis cerana) are better able to remove the mites from each other by grooming, and biting the mite. (PARASITIC MITES OF HONEY BEES Greg Hunt, Bee Specialist, Purdue University)

The parasite-host relationship
between Apis cerana and varroa seemed to have
reached equilibrium because of the development
of defense mechanisms by this bee species against
the parasite (Peng et al., 1987).

A reasonable goal for a breeding program is to
select honey bees that have heritable mechanisms of
defense against the mites that allow them to tolerate
infestation longer than unselected colonies before
chemical treatments are required.
(SPIVAK AND REUTER: Varroa IN HYGIENIC HONEY BEE COLONIES April 2001)

Hygienic behavior is one of several known
mechanisms of resistance against V. destructor.
Bees bred for hygienic
behavior detect and remove worker brood
infested with the parasitic mite Varroa destructor
Other resistance mechanisms
against the mites including grooming
behavior, in which adult bees remove
mites from other adults, damaging the mites
in the process
(Field trial of honey bee colonies bred for mechanisms
of resistance against Varroa destructor. A. Ibrahim et al. 2007)

-- 
Peter L Borst
Danby, NY  USA
www.people.cornell.edu/pages/plb6

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