>
> >Are there other references/experiences about treatment thresholds?
>
There is good graph in the following paper from Germany. Colony winter
mortality rises sharply at somewhere around 5 mites per 100 bees.
"Plotting colony mortality
against ‘varroa mites per 100 bees’ revealed
that with as little as 10 mites per 100
bees around 20% of the colonies were prone
to collapse over winter and an average of
50% mortality could be expected if more than
20 mites per 100 bees were present in a colony
in autumn (Fig. 5). However, some of the
colonies with high infestation rates of more
than 30% in October were able to survive the
winter"
> Genersch, E., von der Ohe, W., Kaatz, H., Schroeder, A., Otten, C., Berg,
> S., Ritter, W., Gisder, S., Meixner, M., Liebig, G., Rosenkranz, P., 2010.
> The German bee monitoring project: a long term study to understand
> periodically high winter losses of honey bee colonies. Apidologie 41,
> 332–352.
--
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com
***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software. For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html
Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm
|