A recent Bee-L post:  There is a simple technique anyone can employ. And
that is *breed from your (overall) best stock*.  Has proved to be a
remarkably effective technique for thousands of years.



* Breeding from the best is probably a good strategy if you are raising race
horses or milk cows, but it may be a fatal mistake that the breeders of bees
have been committing for decades. Of course, at one time, in the age of bee
skeps and sulfur, the best hives were the first to go! The beekeepers would
"heft" the skeps and the light ones were killed and harvested because they
probably wouldn't survive, and the heavy ones were also killed, because they
were too good to pass up. So, the average hives were the ones that were spared!

* As beekeepers got smarter, they figured the ones they wanted to keep were
the ones that did the best, but the question has always been: Why do some
hives do better than others? Is it pedigree? Young queens? Luck of the draw?

* But seriously, for the past *twenty years* evidence has been mounting that
not only are the accepted methods of bee breeding not effective in producing
the desired result, but they may be completely wrong in light of the
mechanisms nature has to ensure the continued health and prosperity of honey
bee colonies. Health and prosperity is what we all seek in the end, because
without these, no enterprise can be called "sustainable".

* I quoted this recently, but it serves as a good introduction to what follows:

> Some researchers are wondering if commercial honey bee stocks are based on
too narrow a genetic base—and that this makes them vulnerable to diseases.
To be effective, behavioral defences in particular require a high level of
genetic variation within colonies. This allows colonies to respond
resiliently to the variety of pathogenic and other challenges they face. If
all workers are the same, they may solve one problem brilliantly but be more
vulnerable to others. (from: "What's Killing American Honey Bees?" By
Benjamin P. Oldroyd, in Public Library of Science, Biology, June 2007)



*  Twenty years ago, Tom Seeley and others were starting to form the idea
that there must be a reason why honey bees mate with dozens of different
drones, when even one could adequately do the job. 

> Here we introduce a new hypothesis, not explicitly considered previously:
polyandry [multiple mating] increases genetic variation within colonies,
thereby reducing the likelihood that parasites or pathogens will diminish
the worker/defense force to the point of jeopardizing the colony's survival
and reproduction.   

> The parasite/pathogen hypothesis assumes that the characteristics (e.g.,
virulence) of the parasites and pathogens afflicting colonies in successive
generations are always unpredictable, because of parasite-host coevolution.
This uncertainty forces queens to mate with several males, because they
cannot reliably choose one male carrying resistance to the particular
diseases that may afflict their workers as immatures, adults, or both.  

> Queens of A. mellifera and A. cerana mate with a larger number of males
than any other known Hymenoptera (7-17 times or more and 14-30 times,
respectively. These two honeybee species also harbor a broad array of viral,
bacterial, fungal, and protozoan diseases, as well as parasitic mites and
nematodes. 

> Given that diseases and parasites are ubiquitous and that their
transmission is probably a universal hazard and cost of group living,
thwarting such enemies may be an important force favoring multiple mating in
social animals in general and in social insects in particular. (from:
"Parasites, Pathogens, and Polyandry in Social Hymenoptera" by Paul W.
Sherman; Thomas D. Seeley; Hudson K. Reeve, in The American Naturalist, 
Apr., 1988)



* Dave Tarpy further explored this theory by comparing colonies with *one
father* to ones with many different fathers:

> I instrumentally inseminated honeybee queens with semen that was either
genetically similar (from one male) or genetically diverse (from multiple
males), and then inoculated their colonies with spores of Ascosphaera apis
[chalkbrood], a fungal pathogen that kills developing brood. I show that
genetically diverse colonies had a lower variance in disease prevalence than
genetically similar colonies, which suggests that genetic diversity may
benefit colonies by preventing severe infections.

> Increased genetic diversity affects the division of labour within colonies
by creating a worker force that is collectively more ‘average’. This effect
on worker tasks is particularly pronounced for behaviours that are strongly
influenced by genotype and have a significant impact on colony phenotype,
such as hygienic behaviour.

> It is unclear whether polyandry evolved in honeybees in response to
parasites and pathogens, or if reducing the variance in disease prevalence
is an inevitable consequence of multiple mating. It is clear, however, that
increased genetic diversity within colonies provides them with several
benefits, and thus should be viewed as a trait with pluralistic
consequences. Future work should determine the impact of other parasites and
pathogens and the relative fitness benefits of these multiple mechanisms.
(from: "Genetic diversity within honeybee colonies prevents severe
infections and promotes colony growth" by David R. Tarpy, in Proceedings,
Royal Society. Biological Sciences. 2003 January 7)



* Most recently, Heather Mattila showed that not only does multiple mating
affect the colonies' health, but it also seems to lead to colonies that
produce more bees, more honey, and ultimately allows them to survive where
single father colonies do not:

> Colony size is closely tied to fitness; larger colonies produce more
drones, have higher winter survival, and issue more swarms. Intracolonial
genetic diversity resulted in considerably more populous and resource-rich
colonies, which in turn affected their fitness. Genetically diverse colonies
reared significantly more drones than genetically uniform colonies before
brood rearing declined in September. The larger, genetically diverse
colonies also collected and stored more food than genetically uniform
colonies and all survived a late-August cold period that starved and killed
50% of genetically uniform colonies. The remaining genetically uniform
colonies exhausted their food reserve and died by mid-December, whereas 25%
of genetically diverse colonies survived to May. (from: "Genetic Diversity
in Honey Bee Colonies Enhances Productivity and Fitness" by Heather R.
Mattila and Thomas D. Seeley, in Science July 19, 2007)

* Just what this all means for the bee industry is not certain. However, I
have talked to several beekeepers who do not purchase queens, but
systematically divide the best hives in spring, thereby ensuring that their
colonies have a great diversity of queen *and* drone lines. If I were a
queen breeder (which I am currently not) I would be thinking about getting
as many *different types* of bees as possible and seeing if a really diverse
mixture of types in every colony would have a beneficial effect on honey bee
health and prosperity.

Peter Borst
Danby, NY  USA

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