After clarifying last week what the “dependence on chemicals” means when talking about varroa, I’d like to go a step further. Because, obviously, varroa treatments aren’t the only thing that you can do about it. So, let’s talk about Integrated Pest Management (IPM) and how to transform it into “Integrated Varroa Control”.
IPM is a concept from agriculture. It aims to prevent economic losses by pests in crops. It includes close monitoring, preventive measures, and finally treatments based on need. The sentence I say so often “As much as needed, as little as possible” actually comes from this concept. When working for a company that did studies required for pesticide registration, I did a course to get the permit to apply them myself. Not that I wanted to do that, but I wanted to learn about the farmers’ reality. And as it was a course for farmers, this was a good occasion…
Anyways, the whole thing came back into my mind when reading the paper by Cameron and Ellis about this very topic and how to apply it to varroa treatments. Because, in the end, that’s what I’m always talking about. Though I don’t agree on everything with these authors, but those are just details.
Varroa is a parasite of a managed animal
So, you may have stumbled on this “prevent economic losses” thing. Beekeeping is still treated as if it was something natural, totally different from bad agriculture (because that’s how many beekeepers see farming…). But obviously, that’s not totally true. Beekeeping isn’t natural. Honey bee colonies in the hands of a human aren’t natural. Beekeeping means managing animals. And as always, you can do this good or bad. Like agriculture. Like science. Like anything.
Colony losses are an economic damage. Even if you’re just a hobbyist. You have to replace the colony, you won’t harvest honey from it. Even if you produce honey only for your family: If you don’t get it from your colonies, you have to buy it, don’t you? For a professional beekeeper the economic loss is much more visible, so for them the concept of avoiding them should be a primary goal.
Varroa isn’t only about colony losses, though. It also reduces the production itself. There are several studies and data on how much varroa infestation reduces the honey yield. In a post I wrote some time ago, I discussed how it pays off if you follow good practices and recommendations from science.
If we take this perspective, the premise of IPM totally makes sense: We want to avoid colony losses and maintain the colonies healthy and productive. So, how to transfer this to a “Integrated Varroa Control”?
Setting thresholds
The foundation for IPM is determining economic thresholds. So, at which point do we have an economic damage? And at which level a treatment can still avoid this? Here, the most important thing is to have reliable tools to determine this threshold. And… well… here’s also where the problems begin when it comes to beekeeping.
There are several methods to assess the infestation level. And their reliability… well, let’s say varies. The popular methods of shaking adult bees with powdered sugar or washing them with alcohol or soapy water take only a part of mites into account: Those dispersing, i.e. sitting on adult bees. Depending on when you do this assessment, most of the mites might be in the brood, reproducing. So, a threshold of “3 mites per 100 bees” also needs an indication of WHEN this is valid. Hopefully tied to the state of the colony, and not a month. Because “July” in Florida or Northern Germany looks completely different.
Counting dead varroa mites on the bottom board is a little bit better. But it’s time consuming and not so easy to really see every mite between wax scales, pollen, and whatever else lies there. All these difficulties explain the different thresholds that are floating around between beekeepers.
Anyways, this is an insecurity that also agricultural assessments face. Nobody can really count all the aphids that are on a wheat field. So, let’s say we have a sufficiently valid threshold that’s also adapted to regional conditions. Then, how do we proceed?
The IPM pyramid
IPM has different levels that often are shown in form of a pyramid. At the very bottom of it, we have prevention. At the next level, there are cultural measures (we’ll go into what this all means in a bit). Followed by mechanical, then biological, and finally chemical measures. This means that varroa treatments, those which kill the mites, are only the last resource to use.
This is perfectly summarized by the sentence at the beginning: As much as needed, as little as possible. It doesn’t mean that varroa treatments have to be avoided at all costs, like some understand it. As I said last week: Chemicals aren’t bad per se, they have to be used correctly.
But what do the levels of the pyramid even mean? Let’s take a look at that.
Prevention against varroa
This level focuses on the management. In an ideal case, the conditions in which a pest is able to establish on its host. For instance, Australia prevented the introduction of varroa for a long time by its severe controls when introducing biological material, living animals, etc. But this is also a good example that shows that complete prevention is nearly impossible. Also Norway still has regions without varroa in its North. And protects these regions with clear laws about bee transports etc. But I dare say that also this won’t last forever.
The spread of varroa mainly depends on beekeeping practices, but also on honey bee biology. Swarming, robbing, drifting – these behaviours also carry varroa mites into other colonies. Not everything is in our control.
It’s also difficult to remove the conditions that favour varroa. In the end, all what they need is a bee colony. Varroa infestations aren’t favoured by certain climatic conditions or anything like that. Spacing colonies wide apart helps to minimize the effects of robbing etc. But this is very impractical, especially with the large operations in places like the Americas or Turkey. If you have thousands of colonies, finding enough apiaries to space them far apart…
What’s in our control
But here’s where good practices come in. You can chose the apiaries carefully. You can also avoid robbing and drifting by how you place the colonies, not leaving combs outside, feeding quickly and cleanly. That’s good practice and will help you with other diseases and issues as well. This is an overarching theme in Integrated Varroa Control and beekeeping in general.
Cultural measures
This one is maybe the one I have most issues with… because an example for a cultural measure would be breeding. And you know my opinion on that – I won’t repeat it here, there’s a blog post explaining it thoroughly. But other examples for cultural measures are:
- Trainings about varroa. You can only manage what you know about, in the end. And it gets less overwhelming if you know about the “enemy” (one of my most popular talks, by the way).
- Exchanges with other beekeepers on how they handle the situation. We’re social animals, after all. Talking to others often opens the perspective and shows solutions that a single person didn’t even think about. This can be very helpful – especially if it’s paired with proper training…
- Individual consulting. Even if you learned something, the situation you face may look different or you’re not sure about something. In such a situation it’s good to know whom to call and ask for advice.
- Treatment schemes. Some regions may coordinate treatment times and products to use to avoid reinfestation and resistance.
All these things build a foundation that helps the single beekeeper to deal with the situation and are part of an Integrated Varroa Control. Completely without breeding… but I’d be ok with it if it’s complemented by these other measures.
Mechanical control
This includes physical measures, like cutting out drone brood. Drone brood is more attractive for varroa mites than worker brood – this comes from their original host Apis cerana. If you put a frame with a foundation into the colony (at the margin of the brood nest), the workers will build drone combs. You then wait until the drone brood is freshly capped and remove this comb from the colony. By this, you can “flatten the curve” of varroa infestation during the productive season of the colony.
This is something hobby beekeepers here in Germany use quite often and it’s also part of the treatment schemes. For professionals, however, this isn’t really practical. Another example would be hyperthermia. This means increasing the temperature in the colony above 40°C for a short period of time. Varroa mites apparently are more susceptible to higher temperatures than the bees are.
The issue with this: Even if the (adult) bees don’t die, it’s a severe stress factor. Honey bees try to maintain a temperature range around 35°C in their nest. Higher (and lower) temperatures disturb the development of the brood. And this then has long-term implications for the colony as a whole. So, even if it sounds nice that you can kill varroa mites without chemicals, if and how it impacts the bees isn’t well-studied. Careful.
This level of Integrated Varroa Control, in my opinion, has produced a series of nonsense that I won’t repeat here. So, use your common sense when you hear about some totally safe and 100% efficient stuff in this area…
Biological control measures
This is a very popular one: Wouldn’t it be great to have a disease or predator that attacks only varroa mites and not the bees? Actually, this would be great. However, we don’t know of any natural enemies of varroa mites yet. They’re well-protected in the colony, after all.
There have been some more or less promising attempts. For instance, using fungi that have some success in controlling other mites. This has been studied quite a bit as biological treatment against varroa mites, too. I’m sceptical mainly because I read too much “100%” in these studies. In biological systems, this is always an indicator to look closely if the promise is really kept.
Integrated Varroa Control using biological agents, until now, unfortunately, didn’t have much success. There are also other challenges that need to be addressed. Like the contamination of the hive products. Fungal spores in the honey would be like residues from chemical treatments: Something to avoid. And this is difficult in an environment that is warm and humid like a honey bee nest.
There were also some other attempts, like bacteria. But none of these really led to something that safely killed the mites. And many things that claim to be successful without being backed-up by good data.
This doesn’t mean that biological measures aren’t possible. But it needs much more research and good data before we introduce another biological agent into bee colonies. That can backfire easily… Especially in closed and finely-regulated systems like honey bee colonies.
Integrated Varroa Control in diverse conditions
The last level of the IPM pyramid is chemical control. I.e. the well-known varroa treatments which so many complain about being dependent on. In last week’s post, I already talked about this in detail, so no need to repeat myself. I even discussed the available substances during BeeAdvent last year.
What is left to say here: I totally agree with the statement that chemical treatments are the last measure to take. That’s what I mean when I say “As much as needed and as little as possible.”. Nobody wants you to limitless put chemicals into your colonies. In the end, we also have to care for food security, so reduce residues etc. But, if it’s necessary, then you have to treat.
This also doesn’t mean that the other levels of the pyramid aren’t valid. They totally are. I said it many times, that I would love to see my doubts on breeding contradicted by good data. That’s true also for my doubts about hyperthermia or biological control. We need evidence-based approaches. Not ideological ones. And it has to be tested in different conditions, adapting treatment schemes (also the chemical ones for that matter).
Finally, applying the IPM pyramid to varroa control and beekeeping also doesn’t mean to focus on a single level. Neither the chemical one nor any other. I talk mostly about treatments, for several reasons. First, it’s the area I really know something about. And I prefer talking about things I know. This is also why I say that I’ll be happy to be proven wrong in my opinion about breeding. Secondly, the chemical level is also the level that is most in our hands. The one we have most experience with. In which we have rules to act upon that ensure it’s mostly safe for the bees (if you use them correctly… good practices, you know).
That said, I can only repeat myself: Treat as much as necessary and as little as possible. Respect good practices. Educate yourself. That already includes much of the IPM pyramid and practical Integrated Varroa Control.
