Strategies for Controlling Varroa Mites in Infested Honeybee Colonies

By: Dorina Debreczeni


“If the bee disappears from the surface of the Earth, man would have no more than four years left to live.” – you’ve probably heard Albert Einstein’s proverb. It’s obvious that agricultural crops highly depend on pollinating insects including more than 20,000 species of bees; they are the invisible ‘motive’ of the increasing yield and help us produce sufficient quantities of food. In the last decades many diseases, parasites and poisonous substances appeared which Apis mellifera (honeybees’ Latin name) is under threat from – some of these caused vast damage in beekeepers’ colonies; in addition, they’re spreading in wild species. For instance, Europeans have been in a vague war for at least 40 years already with a mite called Varroa destructor. But what could be the reason for the impotency of modern science in the major struggle against Varroa mites? How is it possible to help bees survive?


The poor health of western honeybees is due to the spreading #Varroa mites. The main problem is that we can only make the Varroa mites’ population sparse but cannot exterminate them completely by the medication we use currently. The infested bee colony dies off within a few years if they are untreated. Researchers want to develop a #medicine which kills mites but spares the bees to ensure an effective Varroa control. That’s such a great challenge and requires a lot of diligence!


These pests originally came from Southeast Asia by bee imports, and now can be found throughout the world except for Australia. Since they were introduced to Europe, they transmit several viruses including RNA viruses such as the deformed wing virus. On the continent more than 3 million of the 15 million colonies die each year on account of the mites. Their unique reproduction make them unstoppable even in heavy conditions.


For around 50 years professionals thought that Varroa mites feed on hemolymph, a blood-analogous fluid in the body of invertebrates (like ticks live on blood of mammals), but the newest researches state that mites preferably need the bees’ fat body which organ contains fat tissue, performs the function of the liver and can be found under the cuticle. In the fat body hormones and proteins create the response of the immune system, moreover, this organ helps in the digestion of pesticides.


Beekeepers control the Varroa mites in various ways and they must find the right balance, so keeping the bees healthy requires a great deal of skills and techniques.


Varroa destructor can be seen by the naked eye so it’s relatively easy to recognize. It multiplies in the brood cells, and by the time the bee hatches, it’s weakened, abnormally sensitive to pesticides. Furthermore, they have a decreasing ability to learn, have a worse memory and a change in their natural behavior. If it were not enough, the mite can also be carried to other beehives.

Deformed Wing Virus

Beekeepers can place synthetic or naturally occurring substances to the hive. After the mite has the contact with the chemicals, it dies and drops off. Beekeepers and vets can use organic acids like oxalic, formic or lactic acid, etheric oils like thymol, or synthetic ones like pyrethroids and amitraz. I would like to highlight some chemical discoveries which have been made to prevent the extinction which would have been caused by the Varroa mites. One of them is published in the Nature magazine and is related to lithium-chloride, which is an inorganic salt. The study shows that LiCl effectively kills mites but not under every circumstance (have a look at the article in the citations); it is a rudimentary try; we must keep up research and find new methods combining Chemistry and Biology.


Physical methods are not as popular as chemical control but can have similar efficiency. These are based on colony manipulation when beekeepers remove and freeze or heat the #drones brood (differentiation of bees is explained in this article:

https://www.thescientificteen.org/post/honeybee-or-queen-a-study-of-the-epigenetic-differentiation-of-bees ). We can also apply a perforated bottom board to prevent mites to climb back to the hive and infest other bees.


One other interesting report caught my eyes – recently, scientists started to practice genetic engineering to breed Varroa resistant bees with certain genes being removed. This new method may be a breakthrough in examining and abolishing these parasites.


Bees’ well-being is influenced by many factors, but mites are their most serious enemies in Western Europe. My purpose is to find and suggest a solution which can provide a stable future for humankind and these little magnificent creatures. Numerous scientists work on finding a solution to this global problem day by day.


Considering all the above, I suggest you take action, #beeaware even a small change matters - for example planting more flowers and trees in your backyard to provide more food for honeybees. There are many actions that can be taken to help save bees in the Earth's ecosystem. (For example in Utrecht, Netherlands all the bus stops’ roof have been covered by plants as a gift for bees: https://www.ecowatch.com/dutch-city-bus-stops-into-bee-stops-2639127437.html ). You can read more about what you can help with on the attached infographics.


ADDITIONAL INFORMATION:

Here you can find my #tips for ordinary inhabitants living in urban areas:

1. Let your yard go wild, do not maw the lawn in your garden or in public places where it wouldn’t be necessary.

2. Flowers, trees, plants, crops, fruits, bushes - bees will love you if you plant many of them. Search for plants according to your local climate.

3. You had better buy products from markets which are made by local gardeners in order to support sustainable agriculture.

4. Organize programs for kids to teach them how fun is to be aware of the life of these little insects and to make action.

5. Instead of harmful artificial pesticides use natural alternatives.

6. Provide them a tray or bowl of water in your garden and allow them to drink. Yes, bees also need water like humans.

7. You can build your own wasp nest or beehive where bees or wasps move to. In some websites you can get instructions to make it yourself.

#savethebees #varroamites #honeybeesparasites #honeybeestreatment


Recommended videos about Varroa mites and honeybees:

https://youtu.be/NpTf9DWAHeg (Bee Health and Varroa Mite)

https://youtu.be/6Y2t81Y8I2Q?list=WL (Varroa Mites: Why Bees are Dying)


CITATIONS

Bayer AG. (2016). Research to protect bees against the Varroa mite. Retrieved from https://www.research.bayer.com/en/bee-protection-varroa-mite.aspx

Boxmeer. (2018, May 17). US Breeding program. Retrieved from https://aristabeeresearch.org/category/blog-news/blog/arista-bee-research/

Delaplane, K. S. On Einstein, Bees, and Survival of the Human Race. Retrieved from https://bees.caes.uga.edu/bees-beekeeping-pollination/other-topics/on-einstein--bees--and-survival-of-the-human-race.html

Delaplane, K. S. Honey Bee Parasites. Retrieved from https://bees.caes.uga.edu/bees-beekeeping-pollination/honey-bee-disorders/honey-bee-disorders-honey-bee-parasites.html#Varroa

FAO. (2006). Chapter 3. Parasitic bee mites. Retrieved from http://www.fao.org/3/a-a0849e.pdf

FAO. (2018). Why bees matter - The importance of bees and other pollinators for food and agriculture. Retrieved from http://www.fao.org/3/i9527en/i9527en.pdf

Ramsey, S. D., Ochoa, R., Bauchan, G., Gulbronson, C., Mowery, J. D., Cohen, A., … vanEngelsdorp, D. (2019, January 29). Varroa destructor feeds primarily on honey bee fat body tissue and not hemolymph. Retrieved from https://www.pnas.org/content/116/5/1792

Ryabov, E. V., Childers, A. K., Chen, Y., Madella, S., Nessa, A., vanEngelsdorp, D., & Evans, J. D. (2017, December 12). Recent spread of Varroa destructor virus-1, a honey bee pathogen, in the United States. Retrieved from https://www.nature.com/articles/s41598-017-17802-3

Ziegelmann, B., Abele, E., Hannus, S., Beitzinger, M., Berg, S., & Rosenkranz, P. (2018, January 12). Lithium chloride effectively kills the honey bee parasite Varroa destructor by a systemic mode of action. Retrieved from https://www.nature.com/articles/s41598-017-19137-5


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