Here is a good report on SBB & IPM.
Experimentation of an Anti-Varroa Screened Bottom Board
in the Context of Developing an Integrated Pest Management
Strategy for Varroa Infested Honeybees in the Province of Quebec
http://www.reineschapleau.wd1.net/articles/AV-BOTTOM%20BOARD.pdf
Regards,
Ernie
There has been some discussion on this here -> http://forum.beemaster.com/index.php/topic,16851.0.html