Minnesota Propolis Production: A Potential Enterprise and Sustainable Honeybee Disease Management Tool

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1 42 Principal Investigator Victoria Ranua Eagle Creek Honey Farm 5284 Eagle Creek Blvd. Shakopee, MN eaglecreekhoneyfarm. com Carver, Hennepin and Scott Counties Project Duration 2015 to 2017 Award Amount $25,000 Staff Contact Meg Moynihan Keywords bee, hive, honeybee, propolis Minnesota Propolis Production: A Potential Enterprise and Sustainable Honeybee Disease Management Tool Project Summary Propolis, the sticky plant resins that honeybees collect, has long been recognized for its human health benefits. This project is investigating whether propolis can serve as a sustainable disease management tool that improves honeybee colony health while reducing outside, purchased inputs. It also explores whether adding a propolis enterprise could generate meaningful revenue for beekeeping operations in Minnesota. Project Description I have been a commercial beekeeper in Minnesota since I run Eagle Creek Honey Farm, which is based in rural Shakopee, and sell honey and bee-pollinated fruits and vegetables. It has been getting more and more difficult and expensive for commercial beekeepers, who earn money from providing pollination services and/or honey sales, to keep bees healthy. Many of these increased costs are associated with the purchase and application of miticides and antibiotics. Diseases seem more prevalent today, and while these management practices are now routine, they still cost beekeepers time and money. I first became interested in propolis s potential to help sustainably manage honeybee diseases after hearing a talk from Renata Borba, a PhD. candidate in Entomology at the University of Minnesota (U of M). Renata presented preliminary results of a study showing that colonies in propolis-encased hive boxes had lower instances of American foul brood and chalkbrood diseases when compared with colonies in typical unpropolized hive boxes. Propolis are sticky plant resins that honeybees collect from evergreen and/or poplar trees. They use it to seal up cracks and crevices in their hives. Scientific literature is rich with information about antifungal, antibacterial, and antiviral properties of poplar tree-sourced propolis. It is used in the food, pharmaceutical and cosmetics industries, and is now a nearly $1 billion industry worldwide. While people have long recognized that propolis has human health benefits, only very recently have researchers suspected that it may also have similar benefits for honeybee colony health. In many other countries, collecting propolis with in-hive traps is a standard enterprise, but it is not common in Minnesota or elsewhere in the U.S. After hearing Renata s talk, I wondered if adding a propolis enterprise to a beekeeping operation would make for healthier colonies, compared to typically-managed colonies. Honey production is a business for me, and I am motivated to keep bees healthy and reduce my per hive expenses while not jeopardizing my per hive revenue. I hypothesized that encouraging propolis production could prove to be good for the bees, good for those who depend on healthy bees to provide pollination services, good for humans who would like to obtain and use local propolis, and good for the beekeeper s bottom line.

2 43 I used 130 of my honeybee colonies for this study, some with propolis traps and some without. I put propolis traps on the tops of colonies, which is where they are typically placed, I also mounted custom-cut traps inside, as Renata had done. I used two races of honeybees: Italian and Caucasian. Renata had warned me that the Italian bees typically used by Minnesota honey producers might not gather enough propolis to show meaningful results. The Caucasian bee, which was re-introduced into the United States in 2013, has the highest propensity to gather propolis. While Caucasian bees are noted for their disease resistance and cold-tolerance, their honey production capacity in Minnesota is currently unknown. I decided to include Caucasian bees in my study along with the Italians. Beekeepers like Victoria check their hives on a regular basis. Propolis traps mounted inside the hive.

3 44 Beekeepers typically assess colony health by colony size (frames of bees), and visually observe disease symptoms (chalkbrood mummies, dysentery, unhealthy looking larvae) and bees with viral disease symptoms such as deformed wing virus, hairlessness, and spasms. In September, I sampled 100 colonies for disease and sent the samples to be analyzed by the U.S. Department of Agriculture (USDA) Agriculture Research Center s Bee Research Laboratory in Beltsville, MD. I also collected each full propolis trap and weighed the harvest to get a per colony yield. This data will give other beekeepers a sense of the production potential per colony. Furthermore, it will tell us whether Caucasian bees do collect more than Italian bees. Propolis consumers generally use it for health reasons. Understanding that levels of pesticides in the propolis are relevant to this market, I sent two samples of my 2015 propolis harvest to the USDA National Scientific Laboratory in North Carolina for pesticide residue analysis Results I first observed honeybees returning to the hive with propolis in April. In July, I began noticing that the bees were depositing large amounts of fresh propolis being between colony frames. However, this observation did not translate into propolis deposition on the traps. Instead of filling the top with propolis, they filled top trap with beeswax! While I had known this was a possibility, I wanted to see how early I could put traps on a colony and potentially get multiple propolis harvests. What really surprised me was that none of the 86 colonies with interior traps had propolis (or beeswax) deposits either! I contacted Renata, who suggested that spacing might be the problem. She told me the propolis traps must be flush with a solid surface (like the hive wall) because if there is a gap of air between the trap and a solid surface, the bees propolis deposition response may not be triggered. I Bees transpost the sticky propolis residues run my colonies with an inner cover, which have a lip that left a ¼ inch gap on their legs, much the way they carry pollen. between the propolis trap and the solid surface of the cover. So I removed all the inner covers and just ran colonies with either a migratory cover, which is a flat type of cover that commercial beekeepers commonly use or a telescoping cover; both allowed me to mount the propolis traps flush with the top (no gaps). After making this change, the bees started depositing propolis in the top traps.

4 45 I first used Velcro strips to attach the interior traps to the hive wall, but then realized that while this method would have allowed for easy harvest, it also created that dreaded gap that prevented bees from depositing propolis. So I swapped out all the Velcro strips for tacks. This change increased my management time, as the colonies were quite large by that time, but in the end I had no gap. Unfortunately, after getting all the traps flush, my colonies still only deposited propolis in their top traps! This was a very different result from Renata s original experiment; she had also placed custom-cut propolis traps inside the hives and got her bees to deposit there. I had originally intended to separate the propolis trap colonies into two additional treatments fall-harvested and spring-harvested traps to see if propolis improved the propensity of the hives to overwinter. However, because none of the colonies deposited propolis in the interior of the colony, I combined the results of all the colonies of each race of bees into one treatment. I removed all of the top traps, since leaving them on over the winter would have created a moisture barrier, which could lead to colony death and moldy propolis in the trap. Table Propolis Yield from Hives With and Without Propolis Traps Italian Bees Caucasian Bees No Trap Trap No Trap Trap N = Avg Propolis Yield (oz) Mean Propolis Yield (oz) Min Propolis Yield (oz) Max Propolis Yield (oz) The average yield of propolis per hive was lower than I expected. In 2014, I ran a test on five colonies and got an average of 6.0 oz of propolis per trap. The traps I used this year were a different brand, and seemed to hold less propolis than my older traps, a difference that I suspect affected the yield. Colonies that produced propolis on the top trap generally only gave me one trap full of propolis, put there were several colonies that gave me two full traps. I had one Caucasian colony that filled three traps. Table Colony Health Snapshot Italian Caucasian No Trap Trap No Trap Trap N (# hives) Brood frames (avg mid- August) Mite count (avg mid-august) Chalkbrood Dysentery Deformed wing virus Hairlessness Unhealthy larvae Note: Numbers indicate the number of colonies displaying symptom, unless it is noted as an average.

5 46 Colony health data from my observations and the samples I sent to the USDA Bee Research Lab in Beltsville are reported in Table 2. There did not appear to be any significant differences in colony health results between the hives with traps and those without, perhaps probably because none of the colonies deposited propolis in the interior traps (Table 2). In addition, some of the Italian colonies without propolis traps had older queens and, I think this fact may have contributed to the fact that we saw the slightly higher mite and disease counts in the Italian no-trap treatment. Next year, I will provide every colony in this study with a first year queen so I can eliminate that age variable. On another note, it seemed to me that by mid-august, the Caucasian colonies were stronger than Italian colonies. When I prepared my 2015 report about the project, results from the USDA lab tests for pesticide residue were not back yet (they take 5 to 6 months to report). At Eagle Creek Honey Farm, we were still working on packaging solutions for propolis, so do not have sales data to report. We will expect to launch the propolis product in Summer Management Tips 1. Make sure that propolis traps are flush against a solid surface. Positioning them this way will trigger the bees propolis deposition response. 2. To prevent bees from depositing beeswax on your traps, place propolis traps only after major honey flow has stopped. 3. If you are using wax paper to prevent propolis from sticking to the wooden hive components, watch out for increased moisture levels in the hive. If you start noticing mold, remove the wax paper. Cooperator Renata Borba, U of M Department of Entomology, St. Paul, MN Other Resources Marla Spivak Honeybee Health, the benefits of propolis. Beecraft. March. 95:3. benefits-of-propolis.pdf