After re-reading this post on biobees.com I decided to close down the hive floor. There is still a small gap between the meshfloor and the floor, so some ventilation will be present but not as much.;
"That study is available here and shows that, at 70% humidity, Varroa reproduce at the highest rate, whereas at 80% they almost stop reproducing completely. In other words, every 1% increase in humidity above 70% in the brood area hurts Varroa.
"That study is available here and shows that, at 70% humidity, Varroa reproduce at the highest rate, whereas at 80% they almost stop reproducing completely. In other words, every 1% increase in humidity above 70% in the brood area hurts Varroa.
This suggests that a perfect hive for Varroa control would be one that allows the bees to maintain as a high a humidity as possible in the brood cells.
So
Small entrance
No through ventilation
No bottom screen
Old comb if possible (to buffer humidity)
Small cells??
Non-porous hive walls?? "
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I want to share with you the most fascinating thing on bees I have ever read outside biobees.com. In the latest issue of NordBi-Aktuellt, the Journal of the Swedish Association for Preserving Apis mellifera mellifera, Swedish researcher Tobias Olofsson at the University of Lund describes his work on lactic acid bacteria. On the subject of hive atmosphere he writes (in my own humble translation from Swedish):
"Lactic acid bacteria form organic acids such as lactic, acetic and formic acid. These are acids used by beekeepers to combat mites and nosema. Lactic acid bacteria are numerous and resemble small factories in the hive where they prosper in the honey stomach, bee bread, bee pollen and honey. Perhaps they produce an arsenal of substances dispersed in the hive's atmosphere? Perhaps the atmosphere in the hive is important to preserve and this would be a reason to disturb the bees as little as possible. Samples from the lab shows that the bacteria produces large amounts of organic acids that seep into the atmosphere. In modern beehives there are bottom screens and entrances at the bottom; how does this affect a potential atmosphere that might prevent disease? The answer is quite logical, but I put the question to Martin Ferm at the Swedish Environmental Research Institute (IVL) in Gothenburg. The organic acids accumulates in a fairly closed room but with a bottom screen with the full thrust of the wind at the bottom and with entrances at the bottom that aired these acids out according to Martin.
Wild bees prefer a hollow tree with only a small gap as opening and they are very careful to seal every crack or hole. We will be investigating this properly: what is the atmosphere like inside a hive if it can be left alone and what does such an atmosphere do to mites? Our pilot study that was conducted in the summer of 2009, in a hive during a typical summer day and while winter fodder was given, was just the beginning. Formic acid and acetic acid were found in the hive atmosphere in the visible amount during a typical summer day and in even larger amounts when the fodder was given.
The Board of Agriculture allocated funds for one-fifth of this project, which means we'll be managing the project on a reduced scale and without pay, but we were thrilled because they dared to bet on such an odd project.
The bees will more or less look after themselves and winter on their own honey. Half of the hives (all of foams) have bottom screen and bottom entrances and the other half have a protected passage in the attic and a completely closed bottom. After 6 weeks, all hives appear to thrive equally well. Data will be collected for a year and will be compared with bacterial organic acids measured with the same equipment in the lab."
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