Tom Barrett wonders if there have been demonstrated benefits of hygienic
behavior in controlling mites.

Steve Taber, a scientist working for the United States Department of
Agriculture, demonstrated many years ago that some bees have an advanced
trait to keep their hive "clean" and that this trait could be used to
advantage in controlling European Foulbrood and Chalkbrood.  He demonstrated
his by cutting out sections of brood, killing them by freezing, putting the
frozen sections back in the hive from which they were taken, and observing
how long it took the bees to pull the dead larvae from the cells and clean
them for re-use.  He found that in any population, some 10% of the hives
would harbor a strain that would be clean the cells in 24 hours or less,
compared to averages of 2-3 times that long.  More important, he found that
this hygienic trait was inheritable and that it was relatively simple for a
beekeeper to select and breed so that 100% of his bees were hygienic.
However, it was very labor intensive to cut out sections of brood, freeze,
and reinsert the cells into the hives.

Marla Spivak, at the University of Minnesota, observed that some bees were
relatively aggressive toward varroa, tearing off legs and trying to expel
them from the hive.  She wondered if this aggressiveness was related to
hygienic behavior and, after testing, determined that the two seem to be
related.  Her observations have been replicated by others.  She also
developed a simpler means of freezing the larva.  She found that by cutting
both ends off a can she could introduce liquid nitrogen to a small area of
brood in a frame, thereby instantly freezing it, without adversely affecting
the other larvae in the frame.

Today, many commercial queen breeders in the US are adding "hygienic
behavior" to the several traits for which they are selecting and, sometimes,
maintaining by instrumental insemination.  The objective is to significantly
increase hygienic behavior from 10% of the general population to a much
higher number and thus obtain some varroa resistance through these means.

Beekeepers can keep UTD on these developments by subscribing to either of
the two US beekeeping magazines  Bee Culture can be found at www.AIRoot.com.
The American Bee Journal can be found at www.Dadant.com.


Lloyd
Lloyd Spear, Owner, Ross Rounds, Inc.  The finest in comb honey production.
www.rossrounds.com