The propolis is a substance produced by bees, traditionally used by humans for its healing properties. The production starts from resinous secretions emitted by plants to protect their buds and vegetative tips. Bees collect, process, and use this substance in various ways within the hive. Its ancient name, propolis, comes from the Greek terms pro = in defense and polis = city. The reference is to bees’ use it to protect the hive from external threats.
Today, we delve into what propolis is and how bees produce it. Additionally, we understand its use in organic agriculture to enhance plants’ natural defenses against fungal diseases and pests.
What is Propolis
As mentioned, propolis originates from resinous substances emitted by plants on buds and vegetative tips. It is produced by the lymphatic system to protect the plant from external agents. It is a natural, gummy, balsamic resin rich in essential oils and components. This substance varies for each plant species and is collected and processed by bees. They mix it with saliva and wax, enriching it with enzymes, transforming it into propolis. The finished product is then transported to the hive by foraging bees, using the robust baskets on their hind legs. Within the hive, it is used for various purposes, primarily as a natural barrier to restrict the entrance to the nest, thus protecting it from external agents. Secondly, for its fungicidal and antibacterial properties. In essence, bees use it to disinfect the interior of the hive.
Consistency and Diversity of Different Types of Propolis
Bees prefer many trees for propolis production. Among these are: poplar, birch, alder, hornbeam, plane, plum, cherry, fir, pine, elm, willow, oak. These are very different plant species, growing in different ecosystems. For this reason, there is not only one type of propolis. Physical characteristics and contents vary depending on the harvested species, including odor, taste, and color. For example, the color ranges from yellow-green (predominance of pines) to reddish (predominance of poplars) to black (predominance of birches). And amid these variations, there are numerous nuances. The smell, very aromatic, varies based on the resinous substances in the plant. The taste can be pungent and bitter or sweet. The consistency varies depending on the usage temperature. Raw, collected in the cold, it is hard and brittle. But as soon as it is manipulated, it becomes ductile, increasingly malleable as the temperature approaches 30 °C. At higher temperatures, it becomes sticky and viscous, while at 65-70 °C, it melts.
What It Contains
For the same reasons mentioned earlier, the exact chemical composition of propolis varies widely depending on the collection area. Scholars hypothesize an indicative composition, taking into account the main components found in studies conducted worldwide. Namely:
- 50-55% resins and balms (terpenes, polysaccharides, uronic acids, aromatic acids, aromatic aldehydes, caffeic and ferulic acids, cumaric aldehydes)
- 25-35% wax (fatty acids, oxyacids, lactones)
- 5-10% volatile substances, including 0.5% of essential oils
- 5% pollen
- 5% various organic substances, including the most important flavonoids (chrysin, galangin, isovanillin, isalpin, pinocembrin, pinobanksin, pronostrobin, vanillin, kemferide, sakuranetin); benzoic, caffeic, ferulic acid; cinnamic alcohol; minerals (aluminum, calcium, chromium, copper, iron, manganese, lead, silica); vitamins B, C, and E
One of the peculiarities of propolis is its richness in flavonoids, the plant pigments. These are valuable substances that serve a dual function for plants: protection and stimulation of important metabolic functions. Flavonoids provide propolis with most of its antimicrobial properties. For example, flavonoids such as galangin (abundant in broad-leaved forests) and pinocembrin (from coniferous forests) are substances with bacteriostatic action. Those rich in sakuranetin, instead, have pronounced antifungal activity. Other aromatic substances enhance propolis’ bactericidal and antifungal properties. These include benzoic acid, ferulic acid, caffeic acid, and xanthorin. Other properties of propolis include:
Over the centuries, all these properties have led to propolis being considered a natural pharmacy.
How Propolis is Obtained
Propolis can take various forms and preparations. The simplest is raw propolis, obtained through bees’ natural activities.
This raw version can be obtained in two ways. The first is the periodic cleaning of the hive, where pieces of propolis are collected by simple scraping. The issue with this type of collection is the impurities present in the hive, such as wood splinters, insect remains, excess wax, etc. For this reason, many beekeepers prefer the second method, stimulating bees to propolize. This process involves placing special grids with a plastic net for collection in the hive. The grids are placed instead of the hive covers during the bees’ peak collection periods, namely spring and late summer. The grids create a flow of warm air from the center of the nest upwards, towards the net. This warm air stimulates the bees to propolize more quickly. The propolis thus obtained is impurity-free, hence of better quality. Another advantage is in terms of yield for the beekeeper. However, it should be noted that this type of work represents a forcing for the bees.
How Propolis is Used
For human use, propolis can be taken in its raw form, placing it in the mouth and letting it dissolve. It can also be used pure, in powder form, mixed with water or honey. In most cases, the mother tincture is used, obtained by macerating propolis in ethyl alcohol.
The Mother Tincture
It has been studied that propolis releases its contents best after dissolving in alcohol. The mother tincture can be prepared at home, with a standard dosage of 70 ml of alcohol and 60 g of pure propolis. This yields approximately 100 ml of 30% mother tincture. To improve solubility, it is advisable to powder the propolis, kept in the refrigerator to facilitate hardening. First, powder it well using a small mortar. Once powdered, let it macerate in alcohol for about 30 days. Remember to shake the solution at least every 2-3 days; this facilitates contact between propolis particles and alcohol. After the maceration time, the tincture must be filtered. We recommend doing this gently, using a paper filter and without stirring the sediment at the bottom of the container. The tincture lasts a long time, we can say it has no expiration date. The important thing is to keep it in the dark and in a cool place. If you don’t have the opportunity to prepare it at home, you can find it here. Propolis tincture (in alcoholic solution) serves as the base for other human-use preparations, including:
- Mouthwash: 10-15 drops of mother tincture in half a glass of water
- Soft extract
In any case, there are many propolis-based products available in the market. You can find them here.
Use of Propolis in Organic Agriculture
Due to its fungicidal and antibacterial properties, propolis can be effectively used in agriculture. This substance falls among the products permitted in organic farming, acting as a booster for the plants’ natural defenses.
Its use is recommended to prevent cryptogamic diseases in fruit trees caused by fungi. Specifically, we are referring to powdery mildew, peach leaf curl, viral and bacterial infections, canker, gummosis, shot hole disease, collar rot in fruit and vegetable plants. For pest attacks, propolis has been shown to be effective against: aphids, whiteflies, spittlebug, cottony cushion scale, click beetles, soil-dwelling larvae, mealybugs, leaf miners, olive fruit fly, fruit fly, nematodes. In agriculture, propolis-based preparations can also be used to protect plants from weather conditions, similar to nature. It is useful, for example, against hail damage, frost, and heat strokes. Let’s delve into the recommended propolis preparations in agriculture.
Propolis Preparations for Agricultural Use
Among the propolis preparations for agricultural use, the simplest is the aqueous solution. This is obtained by macerating raw propolis in water. The recommended dosage involves macerating 150 g of raw propolis in 1 liter of water for 15 days. To improve dissolution and dispersion in water, it is advisable to add an egg white. The solution should be stirred every 2 days. After the maceration period, the aqueous solution is filtered and stored in dark glass bottles (like these).
In organic farming, this is the most commonly used propolis preparation. It is obtained by combining equal parts of an aqueous solution and mother tincture. For example, 100 ml of the aqueous solution mixed with 100 ml of mother tincture. The resulting hydro-alcoholic solution can be diluted in an additional 100 liters of water and used on plants every 15 days. If you have difficulty with self-production, you can find it here.
Hydro-Alcoholic Solution with Sulfur
To enhance the effectiveness of the hydro-alcoholic propolis solution, especially against cryptogamic diseases, sulfur is added. It’s important to note that regular sulfur powder is not used; instead, molasses sulfur, Sulfar, is used. This is a specific formulation based on sulfur on a protein carrier, less aggressive than conventional sulfur powder. Sulfar, available in the best agricultural supply stores, is permitted in organic farming and is added to the hydro-alcoholic solution at a rate of 250 g per 100 liters of water.
Propolis with Sodium Silicate
As discussed regarding peach leaf curl, propolis (in hydro-alcoholic solution) can be enriched with sodium silicate (at 1.5% on plants in vegetation and 2.5% on plants at rest).
This propolis preparation is recommended as a substitute for mineral white oils in the treatment against scale insects. In this case, the finely ground powder version is used, left to macerate for 5 days in olive oil. The dosage is 25 g of propolis per 1 liter of oil. After the maceration period, the upper part of the sediment-free solution is extracted. Once the oil is extracted, the hydro-alcoholic solution is added in a 20% proportion, resulting in a ready-to-use oleate. The oleate is directly brushed onto fruit trees infested with scale insects. Some of the trees susceptible to these pests are the fig and lemon.
Propolis with Beeswax
Lastly, propolis combined with beeswax finds widespread use. It is a healing ointment, excellent for treating wounds on trees after pruning operations. This prevents fungal attacks that find an easy entry into the tree’s wounds. The cream is prepared by melting beeswax in a double boiler, to which mother tincture and vegetable oil are added. The dosages are: 45 g of beeswax, 30 ml of propolis tincture, and 25 ml of vegetable oil.