How do bees make propolis to seal their hives?
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How Bees Make Propolis to Seal Their Hives
Collection of Plant Resins and Exudates
Bees produce propolis, also known as "bee glue," by collecting resinous substances from various parts of plants, including buds, leaves, and bark exudates. These resins are primarily sourced from trees such as poplars, pines, birches, and willows, among others . The bees gather these materials painstakingly, often from specific plants that produce secondary metabolites with antimicrobial properties.
Mixing with Saliva and Beeswax
Once the bees collect the plant resins, they mix them with their saliva and beeswax. This combination results in a sticky, resinous substance that is both adhesive and protective . The bees' salivary enzymes partially digest the resins, enhancing the material's properties for use within the hive.
Application in the Hive
Bees use propolis to seal cracks and crevices in their hives, smooth out internal walls, and protect the entrance against intruders and environmental threats like wind and rain . The adhesive properties of propolis make it an effective material for these purposes, and it adheres well to various substrates, including glass and PTFE, even under wet conditions.
Chemical Composition and Variability
Propolis is composed of a complex mixture of more than 300 compounds, including phenolic compounds, aromatic acids, essential oils, waxes, and amino acids . The specific chemical composition of propolis can vary depending on the plant sources, geographical location, and season . For instance, propolis collected from different regions may contain varying concentrations of n-alkanes, n-alkenes, and triterpenoids, reflecting the local flora.
Protective and Antimicrobial Properties
One of the primary functions of propolis is to act as a natural antibiotic, preventing bacterial, viral, and fungal infections within the hive. It also serves to embalm intruders like mice and reptiles that may enter the hive, preventing their decomposition and potential spread of pathogens. The antimicrobial properties of propolis are well-documented and have been utilized in various medicinal applications, including wound healing and treatment of infections.
Conclusion
Bees make propolis by collecting plant resins and exudates, mixing them with their saliva and beeswax, and using the resulting substance to seal and protect their hives. The chemical composition of propolis is highly variable, depending on the plant sources and environmental conditions. Its primary functions include sealing cracks, smoothing hive walls, and providing antimicrobial protection, making it an essential material for the health and maintenance of bee colonies.
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