Change Your World Week Winter 2022 (Archived)

The worlds honeybee population is greatly declining. According to The Food and Agriculture Organization, the United States bee population has more than halved since the 1940s going from 5.7 million managed colonies to 2.7 million. This is very concerning in part due to the role honeybees play in pollination and by proxy, to the ability to grow crops around the world. The diminishing bee population is most likely multivariant in nature. It is extremely likely that factors such as environmental change, loss of habitat and incorrect pesticide use are all playing a role in the loss of our bees. However, there is one factor affecting the bee population, rooted in microbiology, that is more dangerous than all of the others.

            What looks to be one of the biggest pieces of the puzzle that has come to light in the past decades is the emergence of the parasitic mite, Varroa Destructor. This small parasite has caused large and catastrophic affects to the bee population of not only the United States but the entire world. Since their invasive introduction to the United States in 1987 the honeybee population began to plumet even faster.  This problem has gotten so bad that, in 2018 the USDA made the startling claim that the Varroa Destructor is the number one problem for beekeepers with 5 or more colonies. This isn’t just a problem for North America.

 Every single Continent with a population of bees has now documented the effects of the Varroa Destructor. As illuded to earlier, the invasion of these parasites are not only devastating to bee populations, but also extremely aggressive. For example, New Zealand north-most island first documented the invasive mite in 2000. By 2013 all regions of the entire country had been ravaged by the parasite, leading to a 16% decline in overall honeybee colonies in the 13-year period alone. (Traynor, K. S.,2020) This is a sad but not uncommon statistic when looking at the  spread of Varroa.  

This picture shows a Varroa mite on the back of a honey bee

The Varroa Destructor lodges its mouth between the thorax and the abdomen of the bees or their larva and feeds. Unlike many parasite more commonly known by humans. V. Destructor doesn’t feed on blood, instead the parasite targets the Fat body of its hosts. This is exponentially worse for honeybees. This fat body of bees are crucial for survival and have even been proven responsible for many essential functions like: immune response, nutrient and water storage, metabolic regulation, growth development and metamorphosis. (Noël A, 2020)

Parasitism of the mite can directly damage physiologic factors of an individual bee like the average weight, size, water content as well as reproductive health, ability to fly and orientation abilities, like homing and foraging. On top of this, infected populations will also see similar effects on future generations of bees as well. This is because the Varroa mite reproduced by infesting the brood cells before they are sealed and feeding on the larva. (Noël A, 2020) If that weren’t bad enough, there is another way in which the Varroa Destructor decimates host population.

 Like most parasitic creatures, Varroa Destructor can act as a vector for transition of pathogens. The presence of V. Destructor is closely associated with several viruses to be colonies. Based on the newest research, vectoring has been directly proven in two major cases. The first is the deformed wing virus. Which as it sound will cause an affected bee to grow thin, underdeveloped wings, rendering it unable to fly successfully. The second case is acute bee paralysis virus (ABPV). This virus is extremely detrimental to an afflicted population’s ability to function in general. 

This shows a bee with deformed wing virus, notice the difference!

               To start with the bad news, much of what scientists and bee handlers have attempted up to this point has been ineffective at handling the parasitic problem. There have been many attempts to find the silver bullet that will halt the spread of Varroa Destructor as well as the pathogens it may carry. However, the mite has proven to be very resilient. They have shown the ability to quickly develop resistance to the pesticides they have encountered. Mite pesticides like Fluvalinate have come in and out of use in a very short time frames due to the parasites ability to adapt. Because of this, even when a pesticide is still working there is a very low chance it will continue to for a long time. There are other tactics to lower the spread and diminish on an individual colony basis, but the strategies are far from optimal. Most strategies put excess stress on the bees and tend to be so time consuming that they aren’t always viable on a large scale. (Traynor, K. S., 2020)

The good news may sound a bit negative at first glance but there is a silver lining. There is a lot that we have yet to learn on Varroa Destructor and interactions with honeybees. In fact, this is an extremely new and growing field of research. For example, the true mechanisms of action regarding the dietary habits of the mite have only just come to light as of 2019. Before this point much of the science we have known, operated under the misconception that Varroa fed on blood and only feasted upon larva. These misconceptions were conclusively disproven by Ramsey, S in the article, “Varroa Destructor feeds primarily on honey bee fat body tissue and not hemolymph”, The reason I emphasize all of this as good news is due to the fact that there is a lot we have to learn on the topic and there are many avenues being explored for possible solutions.

Some articles have found promising evidence that selective breading approaches could be a much-needed answer to the problem. For example, Scientists have been looking at adaptions in behavioral patterns in relation to hives ability to mitigate the spread of Varroa. The most prominent studies have been on hygiene practices such as bee grooming (Thaduri, S., 2020) as well as brood cell recapping (Oddie, M., 2020) both of which showed to be effective strategies against the parasite. It is even now possible to commercially purchase bee strains that exhibit increase grooming as well as mite biting. (Traynor, K. S., 2020) Although none of these are quick fix solutions, some of these genetic solutions may just prove to be the long term plan the world needs.

While we wait for the science to catch up to the problem, there are still things each of us can do to help incite real change. A big part we can all play is by spreading awareness and doing whatever we can to delay the decline of our bee population. Delta college has shown this firsthand. Currently Delta is a certified bee campus. Although, I believe even in our college community there is more, we can do.  A couple years back, there was a proposal by the faculty to start cultivating beehives on campus and even form a class around the process. The proposal was rejected but this doesn’t need to be the end of the story. By raising awareness and attempting to get a new proposal off the ground, our little campus could make a big difference. As a community, we could even work on cultivating bees genetically resilient to the parasites as well. All of this could be an extremely helpful part of the mitigating the damage the Varroa Destructor has done on the world we live in.

 Below I have also attached the links to a few charitable organizations dedicated to helping bees. several choices have been included to help anyone interested make an educated decision. There charities do great work in conserving and restoring natural land for our pollinators and funding research related to the bee related problems we face.

Fao.org. FAO's Global Action on Pollination Services for Sustainable Agriculture | Food and Agriculture Organization of the United Nations. (n.d.). Retrieved February 8, 2022, from https://www.fao.org/pollination/en/

Help the bees. (n.d.). Retrieved February 8, 2022, from https://pollinators.msu.edu/help-the-bees/

Honey Bees. USDA APHIS | Honey Bees. (n.d.). Retrieved February 8, 2022, from https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/honey-bees/honeybees

Thaduri, S., Stephan, J.G., de Miranda, J.R. et al. Disentangling host-parasite-pathogen interactions in a varroa-resistant honeybee population reveals virus tolerance as an independent, naturally adapted survival mechanism. Sci Rep 9, 6221 (2019). https://doi.org/10.1038/s41598-019-42741-6

Katherine M. Elston,Julie Perreau,Gerald P. Maeda,Nancy A. Moran,Jeffrey E. Barrick,Engineering a Culturable Serratia symbiotica Strain for Aphid Paratransgenesis, Applied and Environmental Microbiology, 87, 4, (2021).

Noël A, Le Conte Y, Mondet F. Varroa destructor: how does it harm Apis mellifera honey bees and what can be done about it?. Emerg Top Life Sci. 2020;4(1):45-57. doi:10.1042/ETLS20190125

Oddie, M., Burke, A., Dahle, B., Le Conte, Y., Mondet, F., & Locke, B. (2021). Reproductive success of the parasitic mite (Varroa destructor) is lower in honeybee colonies that target infested cells with recapping. Scientific reports, 11(1), 9133. https://doi.org/10.1038/s41598-021-88592-y

Ramsey, S. D., Ochoa, R., Bauchan, G., Gulbronson, C., Mowery, J. D., Cohen, A., Lim, D., Joklik, J., Cicero, J. M., Ellis, J. D., Hawthorne, D., & vanEngelsdorp, D. (2019). VARROA DESTRUCTORfeeds primarily on honey bee fat body tissue and not hemolymph. Proceedings of the National Academy of Sciences of the United States of America, 116(5), 1792–1801. https://doi.org/10.1073/pnas.1818371116

Traynor, K. S., Mondet, F., de Miranda, J. R., Techer, M., Kowallik, V., Oddie, M., Chantawannakul, P., & McAfee, A. (2020). Varroa destructor: A Complex Parasite, Crippling Honey Bees Worldwide. Trends in parasitology, 36(7), 592–606. https://doi.org/10.1016/j.pt.2020.04.004

Student Author- Cameron Franz