Propolis or bee glue is a

resin A resin is a solid or highly viscous liquid that can be converted into a polymer. Resins may be biological or synthetic in origin, but are typically harvested from plants. Resins are mixtures of organic compounds, predominantly terpenes. Commo ...

ous mixture that

honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to mainland Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the ...

s produce by mixing saliva and

beeswax Bee hive wax complex Beeswax (also known as cera alba) is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in o ...

with

exudate An exudate is a fluid released by an organism through pores or a wound, a process known as exuding or exudation. ''Exudate'' is derived from ''exude'' 'to ooze' from Latin language, Latin 'to (ooze out) sweat' (' 'out' and ' 'to sweat'). Medi ...

gathered from tree buds, sap flows, or other botanical sources. It is used as a sealant for unwanted open spaces in the

beehive A beehive is an enclosed structure which houses honey bees, subgenus '' Apis.'' Honey bees live in the beehive, raising their young and producing honey as part of their seasonal cycle. Though the word ''beehive'' is used to describe the nest of ...

. Propolis is used for small gaps (around or less), while gaps larger than the

bee space In beekeeping, a Langstroth hive is any vertically modular beehive that has the key features of vertically hung frames, a bottom board with entrance for the bees, boxes containing frames for brood and honey (the lowest box for the queen to lay e ...

(around ) are usually filled with

burr comb In beekeeping, in a Langstroth hive, burr comb, also known as brace comb and bridge comb, are portions of honeycomb built by the bees in other places than in the intended place in the frames. Burr comb is commonly found on the top of frames, parti ...

. Its color varies depending on its botanical source, with dark

brown Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing and painting, brown is usually made by combining the colors Orange (colour), orange and black. In the ...

as the most common. Propolis is sticky above , 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. The chemical composition and nature of propolis depend on environmental conditions and harvested resources.

Types

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 Aspen is a common name for certain tree species in the Populus sect. Populus, of the ''Populus'' (poplar) genus. Species These species are called aspens: * ''Populus adenopoda'' – Chinese aspen (China, south of ''P. tremula'') * ''Populus da ...

, Mediterranean, poplar, Pacific, Brazilian green, Brazilian red, and

Mangifera ''Mangifera'' is a genus of flowering plants in the cashew family, Anacardiaceae. It contains 64 species, with the best-known being the common mango ('' Mangifera indica''). The center of diversity of the genus is in the Malesian ecoregion of S ...

types of propolis.

Purpose

Bees seal the beehive with propolis to protect the colony from the elements, such as rain and cold winter drafts. Propolis functions may include: #Reinforcing the structural stability and reduce vibration #Providing improved

thermal insulation Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with s ...

to the hive and reduce water loss #Providing protection from pathogens, via antifungal and antibacterial properties #Make the hive more defensible against parasites and predators by narrowing the existing entrance (in wild colonies) to a single "choke point" #Mitigate

putrefaction Putrefaction is the fifth stage of death, following pallor mortis, livor mortis, algor mortis, and rigor mortis. This process references the breaking down of a body of an animal Post-mortem interval, post-mortem. In broad terms, it can be view ...

within the hive - bees usually carry waste out of and away from the hive, but if a small

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

mouse A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus'' ...

, 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 Carcass or Carcase (both pronounced ) may refer to: * Dressed carcass, the body of a livestock animal ready for butchery, after removal of skin, visceral organs, head, feet etc. *Carrion, the decaying dead body of an animal or human being, also c ...

in propolis, essentially mummifying it and making it odorless and harmless.

Composition

The composition of propolis varies from hive to hive, from district to district, and from season to season. 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 In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

climates, for example, bees collect resins from

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...

s, such as

poplars ''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood. The we ...

and

conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...

s (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

balsam Balsam is the resinous exudate (or sap) which forms on certain kinds of trees and shrubs. Balsam (from Latin ''balsamum'' "gum of the balsam tree," ultimately from a Semitic source such as ) owes its name to the biblical Balm of Gilead. Ch ...

s (50%),

wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give lo ...

es (30%),

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the ...

s (10%), and

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

(5%). An analysis of propolis from

Henan Henan; alternatively Honan is a province in Central China. Henan is home to many heritage sites, including Yinxu, the ruins of the final capital of the Shang dynasty () and the Shaolin Temple. Four of the historical capitals of China, Lu ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, found

sinapinic acid Sinapinic acid, or sinapic acid (Sinapine - Origin: L. Sinapi, sinapis, mustard, Gr., cf. F. Sinapine.), is a small naturally occurring hydroxycinnamic acid. It is a member of the phenylpropanoid family. It is a commonly used matrix in MALDI mas ...

, isoferulic acid,

caffeic acid Caffeic acid is an organic compound with the formula . It is a polyphenol with a key role in scavenging reactive oxygen species (ROS) generated in energy metabolism. Caffeic acid is also one major polyphenol responsible for maintaining normal le ...

, and

chrysin Chrysin, also called 5,7-dihydroxyflavone, is a flavone found in honey, propolis, the passion flowers, '' Passiflora caerulea'' and ''Passiflora incarnata'', and in '' Oroxylum indicum''. It is extracted from various plants, such as the blue passi ...

. In

neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...

regions, in addition to a large variety of trees, bees may also gather resin from flowers in the genera ''

Clusia ''Clusia'' is the type genus of the plant family Clusiaceae. Comprising 300-400 species, it is native to the Neotropics. The genus is named by Carl Linnaeus in honor of the botanist Carolus Clusius. Taxonomy The closest relatives of ''Clu ...

'' and ''

Dalechampia ''Dalechampia'' is a genus of plant of the family Euphorbiaceae and of the monogeneric subtribe Dalechampiinae. It is widespread across lowland tropical areas (generally below 2,000 m ASL) primarily in the Americas with smaller numbers of speci ...

'', which are the only known plant genera that produce floral resins to attract pollinators. ''Clusia'' resin contains polyprenylated benzophenones. In some areas of

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

and

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

Andean valleys, propolis contains viscidone, a

terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...

from ''

Baccharis ''Baccharis'' is a genus of perennial plant, perennials and shrubs in the Asteraceae, aster family (Asteraceae). They are commonly known as baccharises but sometimes referred to as "brooms", because many members have small thin leaves resembling ...

'' shrubs, and prenylated acids, such as 4-hydroxy-3,5-diprenyl cinnamic acid. Overall,

flavonoid Flavonoids (or bioflavonoids; from the Latin word ''flavus'', meaning yellow, their color in nature) are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans. Chemically, flavonoids ...

phenolic acid Phenolic acids or phenolcarboxylic acids ? are phenolic compounds and types of aromatic acid compounds. Included in that class are substances containing a phenolic ring and an organic carboxylic acid function (C6-C1 skeleton). Two important nat ...

s, and

phenolic aldehyde Phenolic aldehydes are derivatives of phenol. Phenolic aldehydes can be found in wines and cognacs. Examples : * Hydroxybenzaldehydes * Dihydroxybenzaldehydes * Vanillin and isovanillin * 2,3,4-trihydroxybenzaldehyde can be isolated from ''Ant ...

s are common constituents, while

coumarin Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by an unsaturated lactone ring , forming a second six-me ...

stilbene Stilbene may refer to one of the two stereoisomers of 1,2-diphenylethene: * (''E'')-Stilbene (''trans'' isomer) * (''Z'')-Stilbene (''cis'' isomer) See also * Stilbenoid Stilbenoids are hydroxylated derivatives of stilbene. They have a C6–C ...

s, and

lignan The lignans are a large group of low molecular weight polyphenols found in plants, particularly seeds, whole grains, and vegetables. The name derives from the Latin word for "wood". Lignans are precursors to phytoestrogens. They may play a rol ...

s are less common.

Uses

Traditional medicine

Propolis has been used in

traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) refers to the knowledge, skills, and practices rooted in the cultural beliefs of various societies, especially Indigenous groups, used for maintaining health and treatin ...

, with a rating that it is "possibly effective" for treating

mouth ulcer A mouth ulcer (aphtha), or sometimes called a canker sore or salt blister, is an ulcer that occurs on the mucous membrane of the oral cavity. Mouth ulcers are very common, occurring in association with many diseases and by many different mechanis ...

s and improving

blood sugar The blood sugar level, blood sugar concentration, blood glucose level, or glycemia is the measure of glucose concentrated in the blood. The body tightly regulates blood glucose levels as a part of metabolic homeostasis. For a 70 kg (1 ...

levels in people with

diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...

Musical instruments

Propolis is used by some string-instrument makers (violin, viola, cello, and bass) as a

varnish Varnish is a clear Transparency (optics), transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmente ...

ingredient. A tincture of propolis may be used to seal the surface of newly made violin family

bridges A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somet ...

, and may be used in the maintenance of the bores of

pan flute A pan flute (also known as panpipes or syrinx) is a musical instrument based on the principle of the closed tube, consisting of multiple pipes of gradually increasing length (and occasionally girth). Multiple varieties of pan flutes have been ...

tubes. Claims that

Antonio Stradivari Antonio Stradivari (, also , ; – 18 December 1737) was an Italian luthier and a craftsman of string instruments such as violins, cellos, guitars, violas and harps. The Latinisation of names, Latinized form of his surname, ''Stradivarius'', a ...

used propolis in the varnish of his instruments were disproven in 2009.

References

External links

* {{Authority control Beekeeping Bee products Traditional medicine Xanthine oxidase inhibitors