This article is about a product made by bees. For the fungus genus, see Propolis (fungus).
Two bars from a top bar hive that the bees have glued together using propolis. Separating the bars will take some effort as the propolis has hardened.Propolis on the upper bar
Propolisorbee glue is a resinous mixture that honey bees produce by mixing saliva and beeswax with exudate gathered from tree buds, sap flows, or other botanical sources. It is used as a sealant for unwanted open spaces in the beehive. Propolis is used for small gaps (around 6 mm (1⁄4in) or less), while gaps larger than the bee space (around 9 mm (3⁄8in)) are usually filled with burr comb. Its color varies depending on its botanical source, with dark brown as the most common. Propolis is sticky above 19 °C (66 °F), while at lower temperatures, it becomes hard and brittle.
When foraging, worker bees primarily harvest pollen and nectar, while also collecting water and plant resin necessary for the production of propolis.[1] The chemical composition and nature of propolis depend on environmental conditions and harvested resources.[2]
Mixed types of propolis found in European countries with a moderate climate include two or more sources of plant resins (plant species) identified by composition, such as aspen, Mediterranean, poplar, Pacific, Brazilian green, Brazilian red, and Mangifera types of propolis.[3][citation needed]
Providing protection from pathogens, via antifungal and antibacterial properties[4][5]
Make the hive more defensible against parasites and predators by narrowing the existing entrance (in wild colonies) to a single "choke point"
Mitigate putrefaction within the hive - bees usually carry waste out of and away from the hive, but if a small lizardormouse, for example, finds its way into the hive and dies there, bees may be unable to carry it out through the hive entrance. In that case, they would attempt instead to seal the carcass in propolis, essentially mummifying it and making it odorless and harmless.
The composition of propolis varies from hive to hive, from district to district, and from season to season.[6] Normally, it is dark brown in color, but it can be found in green, red, black, and white hues, depending on the sources of resin found in the particular hive area. Honey bees are opportunists, gathering what they need from available sources, and detailed analyses show that the chemical composition of propolis varies considerably from region to region, along with the vegetation. In northern temperate climates, for example, bees collect resins from trees, such as poplars and conifers (the biological role of resin in trees is to seal wounds and defend against bacteria, fungi, and insects). "Typical" northern temperate propolis has roughly 50 constituents, primarily resins and vegetable balsams (50%), waxes (30%), essential oils (10%), and pollen (5%).[7][8]An analysis of propolis from Henan, China, found sinapinic acid, isoferulic acid, caffeic acid, and chrysin.[9]
Inneotropical regions, in addition to a large variety of trees, bees may also gather resin from flowers in the genera Clusia and Dalechampia, which are the only known plant genera that produce floral resins to attract pollinators.[10]Clusia resin contains polyprenylated benzophenones.[11][12][13] In some areas of Chile and ArgentinaAndean valleys, propolis contains viscidone, a terpene from Baccharis shrubs,[14] and prenylated acids, such as 4-hydroxy-3,5-diprenyl cinnamic acid.[15]
Propolis is used by some string-instrument makers (violin, viola, cello, and bass) as a varnish ingredient.[18] A tincture of propolis may be used to seal the surface of newly made violin family bridges, and may be used in the maintenance of the bores of pan flute tubes.[citation needed]
Claims that Antonio Stradivari used propolis in the varnish of his instruments were disproven in 2009.[19][20]
^Ferreira JM, Fernandes-Silva CC, Salatino A, Negri G, Message D (August 2017). "New propolis type from north-east Brazil: chemical composition, antioxidant activity and botanical origin". Journal of the Science of Food and Agriculture. 97 (11): 3552–3558. Bibcode:2017JSFA...97.3552F. doi:10.1002/jsfa.8210. PMID28078783.
^Qiao Z, Chen R (August 1991). "[Isolation and identification of antibiotic constituents of propolis from Henan]". Zhongguo Zhong Yao Za Zhi = Zhongguo Zhongyao Zazhi = China Journal of Chinese Materia Medica (in Chinese). 16 (8): 481–2, 512. PMID1804186.
^Mesquita RC, Franciscon CH (June 1995). "Flower visitors of Clusia nemorosa G. F. W. Meyer (Clusiaceae) in an Amazonian white-sand Campina". Biotropica. 27 (2): 254–8. Bibcode:1995Biotr..27..254D. doi:10.2307/2389002. JSTOR2389002.
^Armbruster WS (September 1984). "The Role of Resin in Angiosperm Pollination: Ecological and Chemical Considerations". American Journal of Botany. 71 (8): 1149–60. doi:10.2307/2443391. JSTOR2443391.
