A new study by researchers from Lancaster University's School of Engineering and Lancaster Environment Centre has revealed that both the colour of propolis - the plant-derived resin used by honeybees to build and protect their hives - and the landscape surrounding a hive can influence its composition.

Using 139 propolis samples collected from beekeepers across the UK in 2025 through an extensive citizen science project, the research provides new insights into this remarkable bee product and demonstrates how citizen science can help researchers gather data at a scale that would be difficult to achieve through conventional scientific studies.

Propolis, sometimes known as ‘bee glue’, is created when honeybees collect plant resins and mix them with beeswax to form a protective substance used to seal and maintain the hive. Humans have used propolis for thousands of years, with applications ranging from adhesives and varnishes to wound dressings, cosmetics, and pharmaceutical products. Today, several thousand tonnes of propolis are produced commercially each year.

Medical, pharmaceutical, and consumer products all require reliable raw materials to ensure quality and safety. However, propolis is a complex material made up of plant resins, wax, aromatic oils, and pollen, and its composition can vary considerably.

While propolis is often described as containing around 30% wax, studies from around the world have reported a much wider range of values. Different countries also apply different standards for acceptable wax content, reflecting variations in local environments. The ideal wax content can also depend on how the propolis will be used. Medical applications often favour lower wax levels because of the antimicrobial and absorbent properties of the resin-rich material, whereas cosmetics and food products may benefit from higher wax content.

To better understand what influences wax content, in their paper ‘Land use and propolis composition: an analysis of wax content of Apis mellifera propolis’, Dr Jenny Roberts, Dr Phillip Donkersley, Dr Stephen Quayle, and Professor Allan Rennie analysed samples collected by volunteer beekeepers between April and September 2025. Participants were provided with collection kits and questionnaires that gathered information including hive location, bee breed, and collection dates. The team then used geographic information systems (GIS) to analyse land cover within both three-kilometre and five-kilometre radii of each hive.

The results revealed a clear relationship between the colour of propolis and its composition. Yellow-coloured propolis was found to contain higher proportions of wax, while red propolis contained lower levels of wax. Brown propolis typically fell between the two.

This finding suggests that colour could provide a simple, low-cost way for beekeepers and commercial producers to assess propolis quality before processing. Such an approach could improve efficiency in industries that rely on specific propolis characteristics by providing an accessible form of quality assurance.

The surrounding landscape also emerged as an important factor. Hives located in urban and suburban areas, which tend to contain more trees and fewer natural grasslands, generally produced propolis with lower wax content. Similar patterns were observed near broadleaf woodland and species-rich grasslands.

In contrast, hives surrounded by arable farmland and improved grasslands tended to produce propolis with higher wax content. Although these landscapes often provide abundant nectar and pollen resources, they generally contain fewer resin-producing plants. The researchers suggest that where resin sources are less readily available, bees compensate by incorporating proportionally more wax into the propolis they produce.

These findings indicate that propolis composition may be influenced strategically through hive placement, opening up the possibility of producing propolis tailored to different commercial applications.

The researchers emphasise that further work is needed to confirm these relationships and understand the mechanisms behind them. They also note that the study focuses exclusively on UK-produced propolis. However, the citizen science approach developed for the project could be replicated internationally, helping researchers build a broader understanding of how landscapes influence propolis composition and supporting more targeted production of this increasingly valuable bee product.

“The beekeeping community have been incredibly generous with both the provision of raw material samples and the sharing of their knowledge”, said lead author Dr Jenny Roberts. “The large quantity of samples received has enabled analysis at a scale difficult to achieve otherwise and I am immensely grateful to all who participated. Future iterations of the citizen science project are currently being planned and future research aims to identify the specific flora that have been visited by the bees, via DNA analysis of the propolis samples – a method already used by the National Honey Monitoring Scheme team.”

https://doi.org/10.1007/s00442-026-05965-8