If a natural population has a lower incidence of disease or parasitism
than a managed population it does not necessarily mean that this
difference has a genetic basis. Peter brought up a good hypothesis to
explain low levels of colony loss to varroa in a feral population in NY
State... low colony density in the feral population. Clearly more
research will be needed to find out the fine-points of what is going on,
but I bet you a dollar for a doughnut the mechanism will not be simple.
There is another well-documented example of unmanaged colonies with
varroa, although these colonies were located close together. I made
reference to this ongoing study from Sweden in an earlier post. The study
found unmanaged colonies survived varroa infestation, but the reasons are
an unresolved mixture of swarming, and selection both on the bee and the
mite. The abstract for this study is at the bottom.
The fact that unmanaged colonies deal with disease is not proof that I
would be better off not managing my colonies. There is a big difference
between a managed and unmanaged system and the economics are just not
there for honey hunting as a living. On the flip side I could never
understand why Peter equated skep beekeeping with being unmanaged. They
are VERY managed, they are just not on moveable combs.
The fact that selection occurs in unmanaged populations is also not proof
that I would be better off forgetting about purposeful selection. There
are examples of how concerted breeding has yielded fruits. High levels of
AFB-resistance were achived in the 1940s by selecting colonies inoculated
with an AFB-comb insert. Steve Taber reported very good success selecting
for low chalkbrood following inoculation with chalkbrood in pollen
patties. Harbo and Harris were able to weedle VSH out of a relatively
susceptible US bee populations by selection. Selective breeding works.
It works with the mass selection strategy Allen was speaking to (breed off
what ever lives and looks strong and gradually move the population
along). It works even faster in the Page and Laidlaw closed population
breeding model (I cite as examples New World Carniolans and maybe even
Everett Hastings' Birch Hills Carniolans (Allen, that is Birch Hills,
SASKATCHEWAN)). It works yet faster with breeding systems not yet
contemplated by honey bee breeders but common in plant breeding, such as a
tiered nucleus breeding scheme. What ever you might think of the green
revolution, Norman Borlaug got his 1970 nobel prize for developing dwarf,
high-yielding, disease-resistant wheat varieties using these same
techniques (a link to a lecture by him):
http://webcast.berkeley.edu/event_details.php?
webcastid=9955&p=1&ipp=1000&category=
So I think its great what we are finding out about feral bees, but I am
looking farther onto how I can translate these examples into concrete
selective breeding strategies or new ways to manage my colonies.
Adony
Survival of mite infested (Varroa destructor) honey bee (Apis mellifera)
colonies in a Nordic climate
Ingemar Fries, Anton Imdorf and Peter Rosenkranz
Apidologie 37 (2006) 564-570
An isolated honey bee population (N = 150) was established on the southern
tip of Gotland, an island in the Baltic sea. After infestation with 36 to
89 Varroa destructor mites per colony, they were unmanaged and allowed to
swarm. For over six years colonies were monitored for swarming, winter
losses, infestation rate in the fall, and bee population size in the
spring. Winter mortality rate decreased from 76% and 57% in the third and
fourth years, to 13% and 19% in the fifth and sixth years. Swarming rates
increased from zero the third field season to 57.1% and 36.4% in the last
two years. The mite infestation on adult bees decreased during the last
two years, from 0.47% in the third year to 0.19% and 0.22% respectively.
Our data suggest that a host-parasite co-adaptation has occurred ensuring
survival of both the host and the parasite. The mechanisms behind this co-
adaptation require further study.
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