> ... The mechanisms whereby smaller and swarmier colonies have greater
resistance to V. destructor are not understood fully, but it is likely that
having relatively few brood, especially drone brood, helps control the
mites....*
Hi Alex, I'm happy to see that you've now changed subject from flooding the
environment with swarms, to mechanisms for mite resistance. There are many
published studies on this subject, that can be downloaded for free with a
bit of effort.
Dr. Seeley's papers are generally readily available, and for the study that
you cited, his original data is freely available in the supplemental
material. Such data was of great interest to me to develop my mite model,
and from it I created a tab (F) to reflect a colony kept in a single
Langstroth brood chamber in Ithaca (with plenty of consultation with Dr.
Seeley).
The rate of mite buildup in test colonies that Seeley ran from captured
feral swarms indicated that they exhibited little resistance. But try as I
might, I had difficulty making them work in my model. Seeley observed that
his test colonies swarmed frequently (pers comm). But even when I input
three swarm events, those colonies still crash at the end of the second
year, unless I add some degree of mite resistance.
But then there are my own personal observations. In colonies in my
California operation the exhibit (for whatever reason) reduced
broodrearing, the mite population tends to build more slowly. So I'm
planning to add a "small colony" factor to input into my mite model to take
this into account.
But the point to keep in mind is that any swarm that successfully
establishes a nest and makes it through the winter, is going to be a threat
to other colonies within 1/2 mile the next season, as their bees drift to
other hives, carrying a high load of mites.
The take home is that if you want to help the process of natural selection
towards mite resistance, the first step is to allow the natural process in
which host density in the landscape decreases due to the point at which
parasite transmission is minimized. From that point, evolution can take
place, and resistant colonies can then repopulate the landscape.
Flooding the landscape with swarms prevents that from happening, and
thwarts the natural process of evolution.
We beekeepers, by maintaining a high host density in the landscape, are the
reason that our bees are taking so long to develop resistance to varroa.
The problem then is, how do we keep unnatural apiaries of bees, while still
allowing the process of natural selection to proceed? The answer is to
control varroa in our managed hives, and to minimize the escape of swarms.
Then the breeders and nature can work together.
Randy Oliver
Grass Valley, CA
530 277 4450
ScientificBeekeeping.coml <http://www.lsoft.com/LISTSERV-powered.html>
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