Although I am not done with deadout analysis it appears that most of my hives that succumbed this winter died out due to either a viral or bacterial infection. I did see signs of the SMS (Serratia Marcescens Sicaria) bacterial infection in several of my deadouts, but without a full fledged biological lab it is hard to be certain. In previous years I addressed deadouts simply by cleaning out all the dead bees and scrapping the bottom board. This had always been sufficient when I thought I was combating a viral infection. I was unsure if this simple cleanup method was sufficient for addressing hives that had succumbed to SMS. I thought the SMS bacteria could not survive the cold of Wisconsin winter without a warm host; either the bees or varroa.
Being unsure I went to the expert on SMS infections; Professor James Burritt at UW-Stout. Here is his response.
“Great to get your message. My best estimation is that the bacterium does not remain viable on the equipment or hive parts. Our results suggest the bacterium is transmitted by live Varroa mites. Don’t hesitate to ask any questions you like, and we can talk by phone if that would be helpful.
So I plan to continue using my present deadout cleaning process as described above. Also please note that it is varroa that transmits this bacteria to the bees so make sure you monitor mite populations and conduct a mite control program.