||Photo E-1. An example of
a hygienic colony that has uncapped and removed over 95 percent
of the brood frozen with liquid N2 within 48 hours.
||Photo E-2. An example of
a non-hygienic colony that has uncapped and removed less than
half of the frozen brood within 48 hours.
Breeding for Hygienic Behavior
Any race or line of bees can be bred for hygienic behavior. We recommend
that beekeepers select for hygienic behavior from among their best
breeder colonies; i.e., from those that have proven to produce honey,
winter well, are gentle, and display all the characteristics desired
by the breeder. A breeder can get a head start on selecting for
hygienic behavior simply by rearing queens from colonies that do
not have chalkbrood.
When colonies are first screened for hygienic behavior using a
freeze-killed brood method, they may not remove all of the frozen
brood within 48 hours. The colonies that remove the most freeze-killed
brood within 48 hours should be propagated by rearing queens from
them. Subsequent generations will remove the brood more quickly,
because hygienic queens from the first generation will produce drones
for the second generation. If the hygienic queens are instrumentally
inseminated with semen collected from drones from hygienic colonies,
or are mated naturally in an isolated area, where all the surrounding
drones are from hygienic colonies, it will be easier to fix the
trait in your line of bees. In time, if many bee breeders select
for hygienic behavior, the frequency of the trait should increase
in the general population of bees, which will increase the chances
that any queen will encounter drones that carry the trait.
The effects of American foulbrood, chalkbrood and Varroa mites
can be alleviated if queen producers select for hygienic behavior
from their own lines of bees. The ability of a colony to remove
freeze-killed brood is correlated with disease and mite resistance;
however, the actual degree of resistance can only be evaluated in
controlled tests when the colonies are challenged with American
foulbrood, chalkbrood, or Varroa mites.
Our experience has shown there are no apparent negative characteristics
that accompany the trait. Years of research experience have shown
it would greatly benefit the beekeeping industry to have productive,
hygienic queens mated with hygienic drones available commercially.