I have a few perks working with Bee Informed Partnership out of the University of Minnesota: 1)I get to build relationships with many commercial beekeepers, 2)I have access to the University of Minnesota lab equipment and 3) I get to utilize Marla Spivak’s great mind along with other members of the lab. Because I have been fortunate enough to have this type of access, I can now test this idea I have had for many years: Can we feed bees antioxidants to improve health? Before I chat about the actual experimental design, I want to give you more background information. By the way, I am excited about writing this blog because I can finally do this experiment after all these years! Sorry if I ramble HA
Why are antioxidants important?
I am sure most, if not all, have heard the term superfood. I think superfood is something we hear a lot about, but really know nothing about. When I think of the term, I envision my time working part-time at target where I would overhear interesting conversations. “I am buying kale so I can live longer” ” Why kale, it’s nasty…” ” It’s a superfood Doug… Don’t you read”. This was just one of many, but a very funny conversations I overheard. Anyway, I digress. But if you ask how a food qualifies as a superfood, many doctors and physicians will say “superfoods are high in antioxidants”. So why are antioxidants so important?
Antioxidants are important for many physiological processes for both human and bee health. This much we know. Antioxidants are known to reduce Reactive Oxygen Species, which cause degenerative diseases such as Alzheimers, Parkinsons, rheumatoid arthritis, and cardiovascular disease (Ames, Shigenaga, & Hagen, 1993; Aruoma, 1998). I want you to imagine Reactive Oxygen Species like this: they are highly charged molecules that steal electrons from lipid membranes. As you can imagine, stealing electrons can be highly damaging. Because of this, Reactive oxygen Species have been linked to many types of cancer. Reactive Oxygen Species can be beneficial, which is why we need them, however, if too many Reactive Oxygen Species build up in your body, it can be very damaging. Furthermore, oxygen inhalation produces these Reactive Oxygen species, so it is tough for either humans and and bees to truly control its production. However, humans and bees use antioxidants to control Reactive Oxygen Species production, which is where antioxidants come in.
Antioxidants can inhibit oxidation of other molecules, which basically means, they inhibit production Reactive Oxygen Species like free radicals. Thus, antioxidants can reduce substantial damage. Our bodies can naturally produce these antioxidants, but oftentimes we get them through our diet. While more research is needed, antioxidants seem promising.
Yes, we see antioxidants are important for humans, but what about bees?
Okay, hold on a second… I was just getting to that point. Antioxidants are abundant in honey, the main source of carbohydrates for honey bees. In fact, only 82% of honey is composed of carbohydrates. While less abundant than the sugars, antioxidants may prove to be equally impactful. Despite the importance of antioxidants in honey, bees often don’t ingest them because beekeeper extract and sell their honey. Commercial beekeepers(and many other beekeepers) extract their honey for obvious reasons: 1) Honey has more economic value than other sugar supplements and therefore, beekeepers are more profitable selling their honey and supplementing colonies with another carbohydrates, and 2) beekeepers risk giving colonies American Foul Brood (AFB) spores (or other contaminants) if supplemented with honey (Graham, 1992). Beekeepers are clearly successful by managing colonies this way. Because of these practices, are bees being malnourished because they are not receiving these necessary antioxidants? I researched this very questions.
Despite limited studies, it seems antioxidants do improve bee health. In many cages studies with individual honey bees, antioxidants: 1)reduce Reactive Oxygen Species, 2)improve metabolism of foreign chemicals, such as miticides and insecticides and 3)increase longevity of honey bees (Mao, W., Schuler, M. A., & Berenbaum, M. R.,2013; Wheeler, M. M., & Robinson, G. E., 2014). While these studies are limited, they do have a lot of information about antioxidants and bee health. But can antioxidant supplementation help ENTIRE colonies better metabolize insecticides, aid battle against pest, pathogens and diseases, or help colonies combat oxidative stress?
Okay, you want to feed them antioxidants, but why Acai?
Fruits are increasing on both domestic and international markets due to its nutritional value. Fruits provide polyphenols (Haminiuk, Maciel, Plata-oviedo, & Peralta, 2012), which are shown to prevent disease associated with oxidative stress. Fruits are a great candidate to upgrade honey bee diet because fruits also contain many of the polyphenols and flavonoids (antioxidants) commonly found in honey. Fruits contain 2 major classes of polyphenols: Phenolic acid and Flavonoids. Fruits also contain many minerals and vitamins, micronutrients important necessary for organismal growth and development. Acai, a fruit native to South America, contains some of the highest levels of flavonoids, vitamins and extractable polyphenols among 18 fruits analyzed (Rufino et al., 2010). Thus, acai is a great candidate to supplement into sugar syrup for bees to improve colony health.
Acai is a great candidate, and I believe supplementation has potential. Many beekeepers do admix products such as Honey B Healthy and Nozevi, but these are limited adjuvants. For example, Honey B Healthy only provides essential oils, which are lipids that stimulate consumption and nozevit only provides tannins, which are polyphenols only found in pollen and bee bread (Gajger, Petrinec, Pinter, & Kozarić, 2009; Gajger & Vugrek, 2009; Kaur, Kumar, & Harjai, 2013). While beekeepers have tried to improve the nutritional value of sugar alternatives, many do not replicate the antioxidant levels in honey. So, here is my main question: Can acai provide nutritional benefits for honey bees? I decided to find out….
The preliminary experiment
I tested whether honey bees would easily consume and survive on acai infused syrup compared to a sucrose sugar control. If bees avoided acai and died more quickly than the sugar syrup control, than further studies would be foolish. I will spare you the details, but essentially, I fed adult bees different concentrations of acai and compared them to the sugar control. I tested different concentrations because if successful, I needed a dosage I could feed an entire colony.
I fed individual bees every week, and measured survival. For each treatment, I had 90 individual bees so it was quite easy to measure weekly survival. Now you may ask, why just measure survival? Well I measured survival because: A) it is very informative, B)this measurement literally requires zero expensive assays, and C)if the experiment failed, I am not out too much time or money. Plus, if the experiment worked, I could easily propose to do more with less of a risk later on.
Research Question: Does feeding acai infused syrup improve honey bee health?
Testable hypothesis: Acai infused syrup increase survival compared to sucrose syrup control.
Note: I wanted to find acai concentrations where bees lived equally or longer than bees consuming the sugar control. If bees fed acai have similar survival to the sugar control, this tells me: 1) bees will readily consume the supplement, and 2) the supplement is not obviously toxic to the bees. Below are my results:
We saw a higher mortality for bees fed a higher concentration of acai (6.4g acai). As it seems, acai does become toxic at a certain concentration. This result tells me anything above this concentration cannot be used for further experiments. But this was not the most interesting result… We found that 10% of the bees fed between 0.1g-0.8g grams of acai lived for 5 weeks post-collection! This was very, very surprising. These bees not only readily consumed acai infused syrup, but these bees lived in isolation for 5 entire weeks. I have searched the web, and 5 weeks is longer than any other study I found. So it seems acai may have potential. But I decided to look into the data further. After reading into the data and my notes further, I observed that the bees not only readily consumed the acai infused diet (based on consumption), but the 0.2g Acai treatment had a higher survival than the sucrose control, especially at 3-6. Thus, acai infused syrup may improve some underlying physiological process for honey bees. While I just performed this experiment on caged bees, it seems to have potential. Like I mentioned earlier, longevity is a very simplistic measurement, but can provide a ton of information. While longevity is influenced by many factors, this study indicates acai is readily consumed by bees and at certain concentrations, acai seems to improve longevity.
After seeing these results, I was ecstatic! This idea I have had for several years, seem to work. Despite certain flaws, I had my concentration (0.2g acai) and I was ready to run a trial on entire colonies.
I have 3 major research questions:
- Does acai improve colony health
- Does dietary acai reduce Reactive Oxygen Species (ROS)?
- Does dietary acai increase cellular detoxification?
- Does dietary acai enhance immunity?
Q1: Does Acai improve colony health?
Before I begin, special thanks to Peterson Honey Farms and General Mills! Peterson Honey Farms has generously leased us 48 colonies to perform this experiment. Additionally, General Mills has provided us funding so we can perform the more expensive assays
We have a total of 48 colonies, which will arrive in Minnesota around May 7th. These colonies are 4 frame nucs and have newly mated hygienic queens. We have two locations, so 24 colonies will go into each. We have two locations because oftentimes, environmental differences can influences studies like this. Thus, we can account for these differences. Each yard will contain 8 colonies that either receive the treatment, the positive control or the negative control, and these colonies will be randomly assigned. The treatment colonies will receive acai infused syrup during regular feedings, the positive control colonies will receive nosevit infused syrup, and the negative control colonies will receive regular syrup. Just to note, nosevit was added as a positive control for a few reasons: 1)it is common additive for beekeepers, 2)it contains some antioxidants, but they do differ from the antioxidants in acai berries, and 3)it is always good practice to have a positive control, which is a control that has a known response.
We will feed the colonies regularly throughout the spring. Because we want the bees to consume more sugar than normal, we will provide the bees with foundation. Other than providing bees with more foundation, we will follow the beekeeper normal management practices. This will be an ongoing study throughout the summer, and we will continually measure colony health parameters monthly:
2)Frames of bees
Full colony health assessment
3)Overt signs of pests, pathogens, and diseases
This colony level trial will be most applicable to all beekeepers alike, so I am excited to see the results! I will keep you post. But like all research, we have some other questions to answer….
Testing our other research questions
To test the final 3 research questions, we will collect bees from the colonies, which we will perform caged studies with. One hundred newly-emerged bees will be placed in cages according to treatment and we will put bees in cages. We will feed these bees sugar syrup as provided in their colony of origin. Mortality will be recorded daily by removing dead bees from cages and amount of syrup consumed will be recorded to determine the volume consumed per bee to ensure there is no effect of supplement on worker preference. Three cages per treatment will be established and the experiment will be replicated three times.
Q2: Does dietary antioxidants reduce Reactive Oxygen Species (ROS)?
I talked a bit about Reactive Oxygen Species earlier, but too much can damage your cells. Basically, Reactive Oxygen species have been linked to many cancers and neurodegenerative diseases. Antioxidants are known to lower Reactive Oxygen Species, so we are basically measuring the amount of Reactive Oxygen Species for bees fed the acai control versus either the sugar or nosevit control.
Q3: Does dietary antioxidants increase cellular detoxification?
Along with reducing Reactive Oxygen Species, antioxidants may increase cellular detoxification. Basically, this will increase the honey bees ability to digest and metabolize insecticides. If it proves true, bees fed antioxidants might “handle” these insecticides better. Super interesting if it does!!
Q4: Does dietary antioxidants enhance immunity?
We all know about immunity. If honey bees have an enhance immune system, they might better handle various pests, pathogens, and diseases that impact their health. It is possible antioxidants may improve their immune system, but we will test whether or not that is the case! I will spare you the detail until later.
I won’t get into this anymore, because the final 3 questions can be very dense. Anyway, they are interesting questions I am excited to report on by the end of the summer! I will post monthly posts on https://www.facebook.com/groups/1624266190961975/?ref=group_browse_new, so please follow to read updates. If any person has thought, ideas, inquiries, etc., please leave a comment below or email me at email@example.com.
Ames, B. N., Shigenaga, M. K., & Hagen, T. M. (1993). Oxidants, antioxidants, and the degenerative diseases of aging. Proceedings of the National Academy of Sciences, 90(17), 7915-7922.
Aruoma, O. I. (1998). Free radicals, oxidative stress, and antioxidants in human health and disease. Journal of the American oil chemists’ society, 75(2), 199-212.
Graham, J. M. (1992). The hive and the honey bee (No. 638.1 H5/1992).
Gajger, I. T., Petrinec, Z., Pinter, L., & Kozarić, Z. (2009). Experimental treatment of nosema disease with “Nozevit” phyto-pharmacological preparation. American Bee Journal, 149(5), 485-490.
Gajger, I. T., & Vugrek, O. (2009). “Nozevit patties” treatment of honey bees (Apis mellifera) for the control of Nosema ceranae disease. American Bee Journal, 149(11), 1053-1056.
Haminiuk, C. W., Maciel, G. M., Plata‐Oviedo, M. S., & Peralta, R. M. (2012). Phenolic compounds in fruits–an overview. International Journal of Food Science & Technology, 47(10), 2023-2044.
Kaur, R., Kumar, N. R., & Harjai, K. (2013). Phytochemical analysis of different extracts of bee pollen. Int J Pharma Biol Res, 4(3), 65-8.
Mao, W., Schuler, M. A., & Berenbaum, M. R. (2013). Honey constituents up-regulate detoxification and immunity genes in the western honey bee Apis mellifera. Proceedings of the National Academy of Sciences, 110(22), 8842-8846.
Wheeler, M. M., & Robinson, G. E. (2014). Diet-dependent gene expression in honey bees: honey vs. sucrose or high fructose corn syrup. Scientific Reports, 4, 5726.