Proplis plays a critical role in keeping a hive of honeybees healthy. Propolis is the superglue and medicine of the beekeeping world. The bees use it to seal off entrances against intruders and to Inhibit fungal and bacterial growth. They even use it to envelop offensive contaminates such as mice that happen to die in the hive. Surrounding the carcass in propolis protects the bees from disease and also eliminates any bad smells.
What is Propolis?
The bees make propolis by gathering resin from trees. They carry this resin back to the hive in their pollen sacs. Once the plant resin is in the hive, the bees mix it with saliva and beeswax to create a sticky and plyable substance that is resistant to bacteria and fungi. Some tree resins contain acaricides. These compounds are natural pesticides that help protect the tree from insect infestations.
University Study: Effects on Varroa and Viruses
A recent study by the Leuphana University of Lüneburg in Germany tested whether propolis plays a role in protecting honeybees against mites and viruses such as deformed wing virus (DWV) and sacbrood virus (SBV).
The study looked at 10 Hives. Five of these hives were provided with extra propolis (“high” treatment), the other five hives had propolis taken away from them (“low” treatment). Researches placed propolis traps in the “low” treatment hives. Once the traps were full, researches gave the propolis to the “high” treatment hives.
The study did not show effectiveness of propolis against Varroa mite counts. However, it did indicate that propolis may interfere with viruses transmited by Varroa. “High” treatment colonies experienced fewer instances of deformed wing virus and sacbrood virus were. Observations of the hives during the study also revealed that “Colonies with added propolis were significantly stronger than the propolis-removed colonies.”
The only problem I see with this study is that no consideration was given to how much work was required by the “low” treatment hives to make extra propolis. The “low” treatment hives may have been weaker because they were wasting time gathering propolis instead of food. The “low” treatment hives would not have been receiving the same nutrition as the “high” treatment hives, and could have had higher instance of DWV and SBV as a result.
I think all beekeepers agree that propolis plays an important role in the beehive. This study does not prove anything that was not already known by the scientific community or beekeepers.
The article does create questions about the impacts of removing elements of the hive. Propolis, pollen, and nectar take time and resources to gather. Comb takes time and resources to build. Removing any of these components will induce the bees to have to gather more, or build more, which will take more time and resources.
So, keep it in the hive. Excess burr comb and proplis is added by the bees for a reason. Whether or not propolis directly protects against viruses, one thing is certain, removing it only causes more work for the bees. The more resources and energy used to repair the hive means less energy will be spent on foraging and preparing for winter.
 Simone-Finstrom, Michael; Spivak, Marla (May–June 2010). “Propolis and bee health: The natural history and significance of resin use by honey bees”. Apidologie. 41 (3): 295–311. doi:10.1051/apido/2010016.
 Drescher, N., Klein, A., Neumann, P., Yañez, O., & Leonhardt, S. D. (2017). Inside Honeybee Hives: Impact of Natural Propolis on the Ectoparasitic Mite Varroa destructor and Viruses. Insects (2075-4450), 8(1), 1-18. doi:10.3390/insects8010015