Propolis Research: Practical Information for Modern Beekeepers and their equipment
Some of you may see me reference Marla Spivak [2 links] from time to time, when the topic of bee propolis is mentioned. The University of Minnesota, where Marla is faculty, has been teaching beekeepers for over 100 years and she focuses much of her efforts on the propolis envelope of resin collecting bees.
I have learned a lot of things regarding honeybee behavior from the beelab at UMN over the last ten years. When honeybees are challenged with a fungus, such as chalkbrood, they will decrease foraging of pollen and increase propolis collection, essentially showing self medication of the colony and a measurable positive result. Colonies challenged with American foulbrood do not show as much reduction as chalkbrood, but there are still some mitigative effects.
Young bees a week old have been shown to have less measured immune response [less antimicrobial peptides] in a colony with more propolis.
Viruses transmitted from varroa are not as evident when colonies contain more propolis, but the mite load is generally unchanged.
*** But what is the practical application for our beekeeping efforts in standard equipment? ***
From examples like Spivak and others, I have changed the way I procure and treat my wooden equipment.
*I personally use\* many Langstroth boxes with rough sawn [un-planed] interiors, which encourage the bees to add more propolis on the hive body. I've also scuffed up interiors with coarse grit sand paper or a wire wheel on a drill. [edit: minor formatting]
I use some sturdy canvas inner covers on top of my colonies to encourage application of propolis there, as well. This greatly increases my propolis envelope in my hives, and I can only assume, improves the health of my bees.
Over the past few years, forward thinking commercial beekeepers listen to the research, and add more heavy propolizers to their apiaries. I have taken the same from the modern research and consider it a benefit to have in my apiaries.
Edit: I originally meant to include the UMN Bee lab studies page which has google drive links to much of their work– https://beelab.umn.edu/spivak-lab/publications