I am just getting back into (hobby level) beekeeping after a many year hiatus. I am located in the Deep South and are subject to virtually year round pest attack. New major pests have forced reevaluation of many old apiary practices. One of the “new” ideas is the screened bottom board. It appears to me that this became popular with the arrival of the Varroa mite as a tool to assess colony infection levels. It has morphed in to a variety of other applications including a holder for a small hive beetle trap oil pan. SBB use raises a number of questions in my mind:
1) Does the screen in fact create easy access to wax moths and SHB’s? It creates a giant opening in the bottom of the hive which might be facilitating infection. Many seem to create a space under the hive that is not patrolled by bees. It appears that many of the screens would hardly slow down wax moths and beetles. Data has been published that the SHB’s are attracted to alarm pheromone. They enter the hive and infect the hive pollen stores with a yeast that creating fermentation products that include attack pheromone, which in turn attracts a lot more hive beetles! Until the bees develop the genetic selection to adequately control the beetle (as the AHB’s do), we need to try to stop the beetles before they enter the hive entrance via various traps. It just seems that having such a hole in the hive defenses is a bad thing.
2) The SBB is used for Varroa mite sampling. This method is reportedly not as accurate as an ether roll or sugar roll, so is the large screen really needed?
3) Increased Ventilation- This may be a double edged sword. The bees may have difficulty regulating the amount of airflow through the hive and there is the potential for too much ventilation, decreasing their ability to control the temperature and humidity inside the hive. If extra ventilation is desired from below, some 1 inch holes in the bottom board that were screened with fine mesh and could be propolized as desired by the bees might be the an alternate answer.
I would be very interested in the thoughts and experiences of others, particularly those who have tried it both ways.