10 December 2021
Honey bee health is the main topic of my work. My concept of this has changed over the years. I started as a Master student looking at parasites of solitary bees. Then I made my PhD thesis on the reproductive regulation of Varroa mites. These things were quite separated for me, the common point being that I was dealing with parasites. The beauty of having more experience though: You begin to make connections, to discover how permeable some boundaries are. Nowadays, I do clinical studies to protect all bee species – even if the studies are done with honey bees.
Overwintering – the bottle neck for honey bee health
Winter is a critical point for bees, not only honey bees. The latter however, have to maintain their activity to a certain extent. Solitary bees or bumblebee queens go into a dormant stage during the cold months. Honey bees, on the other hand, go into a winter cluster. This is an adaptation to their social organisation and keeps them warm during this time. So-called winter bees live for several months. Workers in summer only for a few weeks. In spring, winter bees are real methusalems and have to start with all that work normally done by young workers.
Honey bee health for overwintering needs a series of different factors. Good nutrition. I don’t get tired to repeat this. The part relating to the clinical studies I’m talking about here, however, are varroa treatments. Another thing I talk quite a lot of. The varroa mite has been a gamechanger for the overwintering capacity of honey bee colonies. The parasite weakens the developing bees, transmits viruses, and is a catalyst for the transmission to other insect species.
Treating against the varroa mite, therefore, is a service for honey bees as well as for other bee species. Or even insect species: DWV has been found in many different species. If we translate it to the One Health concept: Varroa treatments are the connection between animal health and environmental health. The condition of managed honey bee colonies and the health of wild living species. It’s a huge responsibility for beekeepers.
The right time for varroa treatments
The most important thing to understand about varroa mites: Their population doubles every month as long as they can reproduce. I.e. as long as brood is present. If you want to know more about varroa biology, check out my Bee Health Course. Here, the important thing to understand: This dynamic determines the times when to treat against the parasite.
As you can see on the chess board above, the varroa infestation follows an exponential course. This also means that you have to treat BEFORE there are problems. A varroa treatment, if you want, is always preventive. Because you avoid the infestation getting too high. You push down the starting point for the doubling. It’s ensuring honey bee health for the future, not only for the moment of the treatment.
A summer treatment improves the health of the winter bees. If they grow up with a low infestation, their fat body is larger, and they carry less DWV. A treatment in winter means that the colonies start with a low mite infestation into the season. They will be more productive in summer. You stay at the first four rows of the chess board and don’t arrive at higher level when there’s still nectar flow. Treatments during honey production are a no-go! Not for honey bee health, but for product quality.
Clinical studies for good treatments
Treatments against varroa mites have to be efficient on killing the parasites, but safe for the colony. They’re drugs after all. And that’s where clinical studies come in. Before a product gets on the market, it has to be thoroughly tested. There’s much more to it than clinical studies. But these are a crucial element for the health of the colonies treated with them in the future. And, by this, also for the impact beekeeping has on the health of wild bees.
The question “does it work?” needs an answer under real conditions. You have to be able to give clear indications on the efficacy. Therefore, clinical studies follow a certain procedure to provide good data. You will be counting a lot of mites, filling out a lot of forms and doing quite a bit of statistics to do that. Beekeepers often assume that a treatment worked when a lot of mites fall down on their bottom boards. But actually, it’s much more important how many mites remain in the colony.
Let’s say, after a treatment you count 2,000 mites on the bottom board. You’re happy because your colonies got rid of so many mites. Let’s say that the treatment really worked well. There are only 100 mites left in the colony. This is an efficacy of 95%. Great! But let’s say you see the same 2,000 mites on the bottom board. But there are still 500 mites in the colony. This is only a 80% efficacy – but you saw the same result from the outside. And the consequences for the colony are noticeable – double 100 for four months or 500. It’s 800 mites in the first case and 4,000 in the latter. Quite a difference, isn’t it?
Efficacy and safety for honey bee health
To reach an efficacy really improves honey bee health, you have to know what stays in the colony. That’s why in clinical studies you do a so-called “critical treatment”, with another product. Then you count also the remaining mites. Every single mite. Only then you can really tell something reliable on the efficacy of the product. Obviously, this isn’t practicable for beekeepers. This is why they get the product when it’s ready and they just have to use it. A registered product, one you can go to the veterinary authority and complain if something goes wrong. Because the manufacturer is responsible for the indications given on the label.
In addition, we also test the safety for the colonies. Like all drugs, varroa treatments can have side effects. Maybe not only the mites die, but also the bees. The brood may get damaged or the queen dies. The most visible side effect obviously: many worker bees die after the treatment. This is something we assess with special traps over the time of the study. We check for the development of the colonies, the egg-laying activity of the queen, the presence of stores according to the time of the year.
A lot of work for honey bee health
Doing clinical studies doesn’t only mean collecting numbers, it also needs some experience and understanding of honey bee biology. You have to put the numbers into context. Only this combination will produce reliable data. Every single study has its own challenges you have to deal with. The first one being designing the study according to the product you’re testing. How is it handled? Which is the dosage? What happens with overdosage (this is a pre-clinical aspect often combined with clinical studies). Are there modifications necessary to make the treatment practicable for beekeepers?
Clinical studies always follow a standard framework, but a winter study is different from the next one in summer. By doing clinical studies, I’m helping to develop better treatments. To improve honey bee health, but also to protect wild bees from the diseases of the managed cousins.
P.S.: If you want advice on clinical studies or any other part of the efficacy and safety assessments for varroa treatments, contact me with the form below. In a 30-minute call, we can assess if I can help you, your plans and aims. If it fits and you want my services, I’ll be happy to help you. If it doesn’t fit, that’s ok, too.