Alyssum Flowers
Resin from plant on hind legs of honey bees.
https://beelab.umn.edu/propolis
While some of us are inside with cold or freezing temperatures outside, honey bee colonies are very busy trying to keep the queen and the center of the cluster a toasty 93°F. Hopefully they have sufficient stores of honey and bee bread to maintain the energy required to keep the queen and 10-20,000 bees alive for the Winter. Winter preparedness begins in August by keeping varroa mite levels low and the health of the colony high, providing supplemental feed if necessary for the new bees to be “fat” and healthy, and providing Winter protection if necessary. Allowing bees to “help” themselves by storing propolis is part of the solution.
Propolis has been found to be highly beneficial in to honey bee colonies as it has antimicrobial properties. Feral colonies found in trees or walls of buildings are wrapped in what is called a “propolis envelope”. The inside “walls” and ceiling of the tree void (or building wall void) is varnished with a thick layer of propolis which provides waterproofing as well as a barrier from pathogens and prevents the wood from further decay. Only the area underneath the colony where dead bees and debris accumulate has none. Here, mold may be seen growing on the discarded residue.
Propolis is comprised of plant resins collected by honey bees from trees and other plants combined with wax and other substances secreted by the bee. Just as pollen differs in each plant species, the chemical composition of the resins vary as well, so that the propolis contains a complexity of both volatile and non-volatile plant compounds. Resins are used by the plants as a defense against pathogens and insects which may attack it. Healthy plants produce resins with better defense compounds than stressed plants. These plant compounds are then used by the bees to defend the colony from multiple pests and pathogens.
The resins can be excreted as sap at wound sites or on the stem, branches or leaf axils. It is also found on axillary buds, leaf bracts, stipules or the base of fruit or flowers of different plants. Soybeans and peonies are some of the favorite sources of this precious liquid.
Resin dripping from a cherry tree.
https://epod.usra.edu/blog/2022/06/the-resin-of-the-cherry-tree.html
The key tree families sought after for the resin include Pines, Populus spp. (poplar, aspen, cottonwood), Prunus spp. (apples, peach, cherry, rose, etc.), Acacia spp. (Wattles – in Australia and hot climates), birch (Betula spp.), alder (Alnus spp.), horse chestnut (Aesculus hippocastanum), elm (Ulmus spp.), ash (Fraxinus spp.), oak (Quercus spp.) and beech (Fagus spp.). European horse chestnut (Aesculus hippocastanum) and willows are also documented but bees will find resins in plants wherever they are available. Evergreens are also common sources of resin.
Not only is the propolis used for its antimicrobial benefits, but it is valued as a glue and caulking compound to seal cracks and crevices in the colony to protect it from drafts and invaders. Beekeepers can testify that it seals frames and boxes tightly and can be very difficult to “unstick” if the hives are not opened frequently. At warmer temperatures, the propolis is soft and gooey like taffy and becomes a sticky mess on hive tools and gloves, while it is hard and brittle when cold. Bees will also use propolis to encase animals that enter the hive that are too big to remove. Mice and snakes are common victims to be entombed in propolis, preventing them from decaying since that would introduce bacteria into the colony.
Propolis on edge of hive box.
https://entomologytoday.org/2018/11/28/propolis-how-beekeepers-encourage-better-hive-health/
Propolis has been used in human medicine for centuries, probably since honey bees were first used by ancient Egyptians. It is eaten directly out of the hive or frozen and broken into pieces then made into tinctures, salves and ointments to be used on wounds. It is also taken orally for improved health and to fight infections. It can be purchased in toothpaste or in pill form as well. A great deal of research has been done and continues to determine health benefits to humans as well as the honey bee colony. Recent research is investigating if honey bees consume the propolis themselves for protection against disease. The bottom line is that trees are not just valued for pollen and nectar, they are also a vital source of other products to maintain colony health.
References:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7823854/pdf/plants-10-00022.pdf
https://www.wur.nl/en/article/The-Honeybee-winter-cluster-is-warm-and-cosy-but-uses-a-lot-of-energy-.htm
https://www.beeculture.com/propolis/
ABC and XYZ of Bee Culture, pub. 2020 by the A.I. Root Company, 42nd edition. Pg 567-570.
