Introduction
Arista is celebrating its 10th anniversary!
After having started in 2014 with the first group of beekeepers, we are now 10 years into intensive breeding of Varroa-resistant honey bees.
Given this milestone, we want to use this update to look back at the start of Arista, analyze where we are now, see what we have learned and what this means for the future.
In the beginning…
We have to go all the way back to 1983. This was the first year the Varroa mite was found in the Netherlands – about 40 years ago. The mite quickly spread throughout the country and colonies became heavily infected. Beekeepers were informed about control and the first anti-parasitic agents did a good job initially. After application in the hive, you could find whole streets of dead mites on the bottom of the hive. In the early years, the bees could handle quite large quantities of mites.
However, it soon turned out that the Varroa reproduction in the brood cells had a very nasty side effect. To feed its offspring and itself, the mother mite makes a wound in the pupae’s abdomen. Moreover, through this wound, a whole range of pathogenic viruses – via the Varroa – can now enter the pupa. The pupa does develop into a bee, but it is born sick. The pathogenic viruses cause the weakening and eventual collapse of the colony if left untreated.
40 years of problems
Now we are 40 years on and the problem actually has only got worse. What are the reasons for this?
The first cause is that it is in fact quite difficult for a beekeeper to see how heavily infested the hives are. The mites are spending most of the time in the brood and are mainly close to the bottom of the cell. Which means you can only find them if you open and examine part of the brood under a microscope. The mites that are not in the brood are on the bees. However, mostly on the bottom and ventral side of the abdomen. So when a beekeeper removes a comb from the hive and inspects it, usually very few mites are visible as the bees walking across the comb are looked at upon the back. You simply cannot see the mites that are on the bees’ bellies. Therefor it often happens that beekeepers with bee mortality, do not link this mortality to Varroa because they do not actually see them that often.
The second cause is that several chemical agents no longer work because the mites have become resistant to them or because the agents can only be used under certain conditions. Sometimes the agents work only on the bees and not in the brood. In other cases, effectiveness depends on temperature, and the location of application, the concentration of the active ingredient, and/or the amount and frequency of application all are of importance and critical. And even if all treatments are carried out just right, it is essential to remember that the chemicals are effective against the Varroa mite. However… the bee itself is also an insect and can therefore also be weakened by the treatment intended against the Varroa mite. And to make matters worse… the chemicals kill the Varroa mite but have no immediate effect on the pathogenic viruses. The viruses are obviously unable to reproduce properly when Varroa infestation is low and will slowly disappear from the population. However, this can take several months. During that time, the number of Varroa mites increases again – at least until the next treatment.
Many bee associations and institutes help beekeepers with treatment schedules, but it still is complicated, a lot of work and on top of that also depending on the season. This last factor makes it difficult, even for an experienced beekeeper. With a relatively long autumn and warm winter, weak colonies can survive a bit easier because they can still produce brood for a bit longer. However, in this brood, Varroa can reproduce an extra generation (or 2…). This means that colonies that were treated by the book are now in fact one treatment short. Then they start the next season with more mites than usual which leads to extra mortality in the year after the warm winter. A long cold winter can also cause a problem as affected bees do not live as long. Again, this may lead to increased mortality, usually a bit faster than with the warmer winter. And there is the ‘beekeeper’ factor. After a year with less mortality, there is often less treatment, and this affects the following year…
Given the above, it is not surprising that bee mortality is much debated every year and other factors such as the use of pesticides in agriculture are also often blamed. These can obviously have their effects, but many studies show that honey bees are only exposed to these pesticides for a small part of the year and then often at low concentrations. These studies show the same thing time and time again: the Varroa mites with its pathogenic viruses are the cause of honeybee mortality.
The last straw
In 2012, yours truly, a beekeeper since the teenage years, was working as head of vaccine research in Boxmeer at the veterinary drug company MSD Animal Health and in that capacity familiar with viral, bacterial and parasitic diseases, especially their prevention.
During the Varroa treatment with a Thymol product of two beautiful breeding queens, things went wrong. A side effect of the otherwise relatively non-toxic Thymol is that the queen can temporarily stop laying eggs and she can then be removed by the workers. That actually had happened here, resulting in a new daughter queen laying in each of the colonies. But the original breeding queens were off to bee heaven….
This was the straw that broke the camel’s back. After many years of reluctantly treating chemically, the decision was made: either to stop beekeeping or to find a way to get off the dead end road of chemical treatments. The latter became my new mission and I decided to devote the rest of my career to bees.
There is a solution?!
After reviewing the available scientific literature, the work of the USDA Bee Laboratory in Baton Rouge (USDA: United States Department of Agriculture) immediately stood out. Here, work on Varroa resistance had been going on since the 1990s and, in particular, the VSH (Varroa Sensitive Hygiene) work of John Harbo, Jeffrey Harris, Jose Villa and Bob Danka captured the imagination. John Harbo had the hope that there might already be a predisposition to Varroa resistance in the population of US honey bees, but that it can only be selected to a higher level if you make colonies with a queen inseminated with 1 drone (‘SDI’: Single Drone Insemination). This ensures that the workers in such a colony all have the same mother and father. This, as opposed to a normal mating with 10 drones (fathers) or more where any positive traits are diluted so much that they are no longer measurable. And what was the result? Already in the first experiment with 43 colonies (made with a fixed quantity of bees and mites) after a period of 10 weeks, 3 colonies were found to have fewer mites than at the beginning of the trial. This trial (published in 1997) later turned out to be the start of a very successful research program with dozens of publications in which was shown that the Varroa resistance found, was caused by the ‘VSH’ (Varroa Sensitive Hygiene) behavior. This is the behavior of the worker bees cleaning out Varroa-infected brood cells, thus making reproduction of the mite impossible.
From the review of the publications it was clear that the laboratory in Baton Rouge had the knowledge for the possible solution to the problems we also had in Europe with Varroa.
First visit at the USDA
Question was, what to do? I picked up the phone and called Bob Danka, at the time in charge of VSH research…. Already after 15 minutes in this call, it was clear to Bob that a further exchange in Baton Rouge would be most productive and the first visit in June 2013 was a fact! Ralph Büchler (Kirchain Bee Institute, Germany) was invited to come along as well and this led to a very instructive first week including a visit to the VSH colonies, getting to know the researchers in the lab and hands-on brood research which is an important basis of Varroa resistant breeding. Commercial beekeepers were also visited including David Thomas who had a business in Louisiana and in… Hawaii. Whilst talking with Bob and David, the European Buckfast and Carnica breeding programs also came up for discussion, which in fact go a lot further than the US breeding.
Founding of the ‘Stichting Arista Bee Research’
The visit to the USDA only increased the conviction, that we should be able to replicate this in Europe too. Therefore, the Arista Bee Research Foundation was established in December 2013.
Second visit to the USDA
The first visit was appreciated on both sides of the ocean and not long after this one came an invitation from David Thomas and Bob Danka to once again visit the lab in Baton Rouge. In Hawaii, David was running a VSH program using breeding material from the USDA. During this visit in April 2014, Arista was asked to help with this breeding program by implementing European breeding experience. On this trip, the experienced breeder Renaud Lavend’Homme from Wallonia, Belgium came along which further facilitated the exchange of knowledge. Just in time, as in 2014 we were about to start the special breeding in both the Netherlands and Belgium.
Take-off
From that moment onwards, things moved quickly. By running the breeding program in parallel on Hawaii and in Europe (each with bees from its own region), we were able to develop a modernized version of the 1-drone insemination method in small colonies very quickly. We also learned how to best use the large colonies that are inseminated or mated (in a mating station) with multiple drones, in the breeding program.
In this update, we take a closer look at the method we have developed over the past few years and introduce a name for this breeding approach: “the hop-step-jump” and present the 2023 results of the “Italy route” using this method.
The “hop-step-jump” method
Hop
The hop-step-jump method consists of 3 parts, starting with the “hop”: the selection using the 1-drone insemination. Let’s say we started with 100 colonies and, after infestation with extra Varroa mites, we find that in 10 of the colonies an estimated 75% of the mites are removed. This means we then estimate the VSH percentage to be 75%. Next, we take these 75% colonies to Italy for the next part, the ‘step’. In the last 5 years we have thus taken 83 queens/colonies to Italy for further selection.
Step
In Italy, beekeepers make more than 10 daughters from each of those queens. These daughters are brought to a mating station with drone colonies that are already reasonably high VSH. This does not need to be a completely ‘closed’ station; a small proportion of non-resistant drones may also ‘join in’. After mating, the queens are placed in normal large production colonies and the colonies are used for honey harvest. Bee samples are taken several times a year and Varroa infestation on the bees is determined. In the last 5 years, 1144 colonies have been monitored this way for Varroa infestation, honey harvest, etc.
And what appears to happen? There is an actual 3 division in the colonies. Even though all the colonies were mated in the same mating station, some colonies still have quite a few mites (> 3% that might still need to be treated), some have a reasonable low level of mites (2-3%), but some of the colonies have really very low infestations (around 1% or less).
What is going on here? We conclude that the difference can be explained by different resistance levels of the daughters of the original 75% mother. This is quite normal. According to the ‘Mendelian’ inheritance, we can expect that some of the daughters will be close to 50%, some will be 75% and some will be 100%. Unfortunately, this cannot yet be determined with a genetic test. But we now assume that the populations with the very low infections, were the daughters with 100% or at least very high resistance levels. And that is a very important fact for the last part of the hop-step-jump.
Jump
Now that we have an average of 2 out of 10 daughters that have a very low infection level in the colony and therefore probably have a very high resistance level, we can do the third part of the selection. Were we to make new (grand) daughters from these colonies again, they would no longer be purebred as there may have been foreign drones flying around at the mating station. With a bit of bad luck, such a (grand)daughter would be only moderately resistant. So, that is not what we do. What we dó do, is we use these daughter’s drones. We make use of the very special biological fact that the drones, the sons of these daughters, are born from unfertilized eggs. In other words, these drones have no father (from the mating station), but only a mother! And since this selected mother herself is rated as very high VSH, all her sons will be too!
From these drones we collect semen (in Italy) and transport it back to Belgium and the Netherlands. Here we inseminate queens with this very high VSH semen. After selection in the 1144 colonies, 83 daughter-drone colonies have been used from 42 mother queens sent in over the past 5 years. The average Varroa infestation rate of the drone colonies (untreated for 2 years) used was 1.0%.
The transported semen has been used in the Netherlands, among others, for the queens in the Arista hives (~20) that we rent out to donors/sponsors. Each queen receives the sperm of about 10 drones (‘MDI’: Multiple Drones Insemination). We monitor these hives for several traits, but obviously for Varroa mite infestation as well. In the following chart, we give the average mite infestation for spring, summer and autumn of the years 2020, 2021 and 2023.
This table shows the success of the program: mite infestation throughout the year of 1% or less (0.6%, 1%, 0.7%): the blue bars.
We do not have low-VSH colonies as a control, but we have been able to calculate mite infestations for these types of colonies using the Randy Oliver simulation model (Scientificbeekeeping.com) and see that in untreated colonies, mite infestation is 10% at the end of the year. This corresponds with what beekeepers see in untreated colonies.
In the Arista hives, there is no longer see bee mortality due to Varroa, and this without any chemical treatment.
Because the hop-step-jump method works so well and has proven itself in Hawaii and Italy, we now have land mating stations in Belgium and the Netherlands as well. This methodology will have to be rolled out further.
The future
We have laid a very solid foundation in the past 10 years in developing the breeding method and setting up breeding groups with the participation of more than 300 beekeepers. We have an initial good base with a total of 6 paid employees, 3 in Belgium and 3 in the Netherlands. This will have to grow further to have good geographical coverage as well. We can now also select further in width (biodiversity) and ensure that as many lines of different bee races become Varroa resistant.
There has been a lot of support from Arista Netherlands for the German-speaking countries active in breeding. Through the ‘Varroaresistenz 2033’ program, it is now high time for German, Austrian and Swiss support for project leaders in these countries themselves.
Arista spent a lot of time in 2023 and early this year informing the government and beekeepers in Australia where Varroa mite has also set foot. Hopefully a breeding program will be started here as well.
Apart from the Hawaii project, there are only a few small VSH breeding initiatives in the United States, despite the fact that VSH was discovered here. Arista recently received an initial start-up budget from the Dioraphte Foundation and is now making plans with the USDA lab and an initial project leader-candidate to expand breeding activities here too. This is much needed as the US has the highest honeybee mortality rate of around 40% per year.
More research will also be done to support labour-intensive breeding. Arista is taking part in a Genetic marker project (with Inholland University of Applied Sciences and Bejo seeds, financially supported by NL-EU funds) and Fanny Mondet’s VPS odor quick test project (with financial support from Stichting Goeie Grutten). We will provide updates on these as we reach an important milestone.
Financial support
We would like to thank our donors, sponsors and grant providers very much for their support over the past 10 years. Without this support, we would still be “dealing” with increasingly inferior chemical treatments. However, broad support is now needed to further expand breeding towards a (much) larger group of beekeepers with the aim of also providing “normal” beekeepers with a wide diversity of lines. This is the goal for the next 10 years!
BartJan Fernhout