[Bonus] Short - Varroa Treatment Options: Amitraz aka Apivar

[Bonus] Short - Varroa Treatment Options: Amitraz aka Apivar

Jeff: Welcome to Beekeeping Today Podcast Shorts, your quick dive into the latest buzz in beekeeping.

Becky: In 20 minutes or less, we'll bring you one important story, keeping you informed and up to date.

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Becky: Brought to you by Betterbee, your partners in better beekeeping.

Jeff: Hey, everybody. Welcome to this Beekeeping Today Podcast short on varroa treatments. This is a multi-part series covering the different treatment options available to combat this honeybee pest. Each short in this series, we'll cover one specific treatment option. For the series, we've invited Dr. David Peck from Betterbee to join us. In this short, we'll be discussing amitraz, or otherwise known in the trade as Apivar. Hey, Becky. Hey, David.

Becky: Hey, Jeff.

David: Hey, Jeff. Hey, Becky. Thanks for having me back.

Becky: Hey, David. It's so much fun to talk pesticides with you, too. [laughter]

Jeff: Amitraz, Apivar, that's a big treatment option available to us.

David: It absolutely is. For most beekeepers, your relationship with this treatment may depend quite a lot on your scale, because if we can speak honestly here, for the most part, your average beekeeper, most of the beekeepers in the US are going to be using Apivar strips, which contain the active ingredient, amitraz, to kill varroa mites in their hives. If you're talking about the commercial beekeepers, the people who actually have most of the hives, they are using amitraz, that same chemical, but they may not be using the legal Apivar strips in order to treat their bees.

We've got a lot of folks who are using this same molecule, but they're not all necessarily using the legal approved, controlled, manufactured product, which is what we're going to really try to be focusing on today. I think we're going to have to talk about both sides of that because what one set of beekeepers is doing can have an effect on what the other ones are able to do.

Jeff: Let me ask real quick before we get too far down that, just so we can make a distinction. If you go into your local bee store and you buy amitraz or Apivar, it's in a strip.

David: That's right.

Jeff: If the commercial guy is-- are they applying some strip, or are they applying another type of-- is there another modality of treatment?

David: There are two legal ways that I can apply amitraz to my bees, and they're both made by the same manufacturer. I can use Apivar, or I can use a product called Amiflex. The Apivar is a plastic strip that has been impregnated with these molecules that kill mites. The Amiflex gel is you apply it using like a caulk gun, and you just squirt that onto a card, put that on top of your bees. That's two different ways that I can apply it. That was really developed to offer a legal way for the commercial beekeepers to use it. To be honest, I've talked to commercial beekeepers, and they're doing all sorts of things out there that I really wish they weren't.

They tend to be mixing up the amitraz molecule that they're illegally sourcing, and then mixing up with some other ingredients and then putting into their hive. There'll be some kind of a carrier that gets it in there, but it is not that plastic impregnated, slow-release strip that the Apivar strip is.

Becky: Are they doing it because of finances, because of dosage, or because of a little of both?

David: Yes, I think the answer could probably be a little of both. Breaking the law is cheaper than following it, more often than not, I think, but that doesn't stop most of us from following the law. They do sometimes think, "Well, I get better control of it, mixing it up in my big vat out in the barn." I would argue that probably the laboratory that's manufacturing this stuff has pretty precise control, but if you want to quadruple the dose or something, then sure, I guess mixing it illegally in an old tin can would do that, but I don't know that that's the best practice for good bee health.

Jeff: We've jumped forward a little bit on the mode of treatment, but this is a synthetic chemical, correct?

David: That's right. This molecule, just like Apistan and CheckMite's active ingredients, amitraz is a synthetic molecule that is targeted to kill varroa mites in a very specific way. As a result of that, it's pretty gentle on bees themselves. It's not going to be toxic for a human to breathe in. You could sniff an Apivar strip, not that I'd necessarily recommend it.

Becky: Not a recommendation.

David: You're not going to keel over, but there's plenty of products that if you take a big whiff of it, you're going to be knocked right down onto the grass. It's kinder, gentler in some ways, but very harshly targeted for the varroa as long as the way that that molecule is created in the laboratory is going to actually hit the varroa mite where it hurts, as long as the mites don't have any resistance to that molecule coming in and killing them.

Becky: Now, David, if you're going to use Amiflex, do you have to get a special pesticide applicator approval certification?

David: Yes, you do. Yes, the way that was approved in the US, they were able to get it approved quickly and efficiently, but because of that, you need to be a certified pesticide applicator in order to use it. If you've got a great big beekeeping operation and you want to start doing things legally, you could shift in that direction. Plenty of folks have, but for the most part, the average backyard beekeeper is not going to pay to take 16 hours of classes and pay a $1,000 fee or whatever it costs to get that pesticide applicator license. No, us humble mortals are limited, for the most part, to our Apivar strips.

Jeff: David or Becky, how does the amitraz work? Is it ingested? Is it absorbed? How does it affect the varroa mite?

David: The mechanism of action is actually really interesting. It's actually binding to part of the mite's nervous system, and it doesn't kill them directly, it paralyzes them. These mites are getting paralyzed by their nervous system getting too stimulated, and then they fall off the bees and then wind up starving to death on the bottom of the hive or getting chewed on by a bee who catches them when they're indisposed. Becky, you actually have expertise in the way this actually works. These are octopamine agonists, right?

Becky: If we start digging back, I've got a PhD dissertation that does talk about octopamine because I looked at octopamine-immunoreactive neurons in the honeybee brain. That with them being activated when honeybees were doing hygienic behavior.

David: Cool. The advantage here, of course, is that bees and mites both have these octopamine receptors, but they're different. It's not like the bees are sniffing their amitraz strips and then winding up hyperactive, paralyzed, and falling to the ground. The molecule targets the mite receptor, but it doesn't have that same negative effect on the bee's receptor.

Becky: It sounds like a hard night of partying for the varroa who don't actually recover from it.

Jeff: The amitraz basically knocks the mite off the bee, and they fall to their death, or they fall and eventually die. What are some of the pros and cons of using this? Why would a beekeeper want to select the amitraz or Apivar as a synthetic chemical in their beehive?

David: Apivar has no meaningful, I'll say, temperature restrictions. A beekeeper is unlikely, unless they're in a really extreme climate, to be in a situation where it's too hot or too cold to put this onto the hive. It is, when it kills the mites, very effective at doing so. It's very gentle on the bees. It doesn't get soaked up into the comb because it isn't wax soluble. You don't wind up getting the active ingredients soaked up into the wax, so that it's then going to expose the bees and the mites to low levels of it for a long time. In fact, the amitraz molecule breaks down pretty quickly inside of the hive.

It ceases to be amitraz only after a pretty short time being out and about and circulating. That means that you're not going to be building up these residues of it, which is pretty handy.

Jeff: When is it applied?

David: Importantly, you cannot apply this when you have honey supers in place. You've got to use this typically in the spring, before you're putting your supers on, or in the fall after you've taken your supers off, for those of us that essentially put the supers on in late spring and take them off in late summer or early fall. Of course, the removal of the Apivar strips does not necessarily mean the end of your Apivar treatment. Because this is a long-term treatment, and then there's a withdrawal period after you take the strips out of the hive that you also have to respect.

If I say, put these things into my hive in the spring, and the bees are all running around, the amitraz molecules are getting from the strips onto the bees, from the bees onto the mites, killing the mites, and then doing a good job. I leave those strips into the hive for a period of between 42 and 56 days, nearly two months of treatment. Then once I pull the plastic strips out, I am not allowed to put my supers onto the hive for an additional 14 days, another two weeks after that treatment has been removed, just to make sure that it's all been totally purged from the hive, and there's little to no risk of anything getting up into the honey that a human could then be exposed to

A lot of folks find that even if they'd like to use this in the spring, unless they're going out when there's still snow on the ground, they might not be able to get it in and then out before they've got to put the supers on for the spring honey flow. That's why most beekeepers find themselves using this in late summer and in the fall.

Jeff: Right after they pulled the supers.

David: Right. Now, that's of course true for a honey production hive. If you're a beekeeper who's also got a couple of nucs on the side, if you've got an observation hive that you're maintaining for a local school that has kids coming and looking at it every day, if those hives aren't making honey that a human is going to consume, you can use Apivar anytime throughout the year. Here at Betterbee, when we make overwintered nucs, we will make the nucs in the middle of the summer, and then we've just got to keep them small but healthy to get all the way through to the next spring, so somebody can buy them and then start off a big colony from them.

We absolutely use Apivar in our hives in the middle of the summer while the honey flow is on because we know that none of that honey is ever going to be consumed by a human being.

Becky: I think it's important to note that you've mentioned, but just to say this is gentle enough to put in a five-frame nuc, because there are treatments out there that you cannot use on five frames of bees.

David: That's exactly right.

Becky: This is something you can do in five frames.

David: Right, or hives of a different shape. The way the label is written, you put in one strip for every five frames of bees. That means that you've got pretty flexible opportunity if you've got a top bar hive or a hive that is a very non-standard shape, there's still dosage instructions that you can follow that will allow you to use this, which is not true of something that maybe forms a gas inside the hive and needs the hive to be a particular size and volume for it to function correctly.

Becky: And not really hurt the bees.

David: Exactly.

Jeff: Let's talk real quick on the downside of amitraz. This is something we've discussed with other treatments in this series. Varroa resistance to the active ingredient.

David: That's right. Unfortunately, amitraz was celebrated in the same way that Apistan and CheckMite were. That we had this great synthetic miticide, it was gentle on the bees, it killed the mites really effectively, but over the last few years, more than few, at least a decade, there have been slow but sure increases in folks reporting that they're Apivar strips just don't seem to be killing as many mites as they used to. To be honest, that's less beekeepers with a couple of hives in the backyard using these strips. It's more of the commercial beekeepers who are using the illegal stuff.

They're still finding that using this active ingredient, this amitraz molecule, just wasn't having the same effect that it used to. There's been a lot of really good research done on exactly what's happening and exactly what the consequences are for bees and beekeeping. The 2024 to 2025 mass bee die off that was reported and then studied by the USDA, one of the main findings that they came forward with was a lot of the bees that seemed to be dying seemed to have higher levels of the genes in their mites that indicate resistance to amitraz.

They found these dead mites, they tested them, they ground them up and looked at their DNA, and they found gene markers that are at least associated with those mites being more resistant to amitraz. What we found is that the more operations that you look at, especially big commercial operations where we know the beekeepers are using an awful lot of amitraz-based pesticide to keep their mites under control, we find that they're seeing higher and higher and higher levels of those genes for resistance, and they're reporting lower and lower and lower effectiveness of amitraz-based pesticides.

Unfortunately, that means that even if they aren't using the Apivar strip, if they're using the same molecule, it means that there is a risk that there's just more mites in the world that are resistant to Apivar. We experienced that here at Betterbee. We were doing an experiment a year or two ago, and we were using Apivar to keep the mite levels low so that the mites didn't interrupt the experiment. Then, lo and behold, we did a mite check just to make sure, and the mites were sky high. It was because those particular mites happened to have a large number of individuals with this amitraz resistance trait.

The beauty of Apivar is you can put it in as long as you time it correctly. You don't have to worry about the temperature. It's going to be gentle on the bees, harsh on the mites. The problem is you need to trust but verify, because there's no telling for sure before you start whether your mites have Apivar resistance.

Jeff: Do they know if that gene, that resistance gene, is that persistent? Will that eventually breed itself out in a population of varroa?

David: What I do know is one of the scientists who study this is Franklin Kevitch at the USDA, and he's presented data that show a pretty compelling story, that he found that when beekeepers were using Apivar, or rather, let's just say they were using amitraz to kill their mites, if that was all they were using, the levels increased, increased, increased, increased, but if you found a population that had amitraz-resistant mites, and then you stop using the amitraz for a year and you switch to using oxalic acid vapor instead, and that's just one example, I think you could probably switch to a lot of different things.

In his study, you switch over to oxalic acid vapor for a while, and then you go back in and you test the mites to see how many of them are still resistant to the Apivar. The answer is it's a pretty low number. It seems like when you get into that healthy rotation cycle, those good IPM practices where you're using more than one mite aside, which more hobby beekeepers may be doing than than the big commercial guys who might be trying to save a buck and just keep using the same thing because they bought a 55-gallon drum of it or whatever they're up to.

It's possible that the hobbyists are going to have less of a problem with this because they are naturally going to be doing more rotation in their hives, which means that there's less strong selection for every single mite to have and then maintain high levels of those resistance genes.

Becky: Local mite populations matter.

David: Exactly.

Becky: That gets pretty complicated, though, doesn't it? Because your mite populations consist of both resistance and then whatever disease variants they're vectoring.

David: Right. We already talked about your PhD dissertation. I've got a whole chapter, which is all about how varroa mites spread between hives. There's a real problem here because if I have a local population, me and all the other beekeepers around us are using this molecule responsibly, we're using it to keep our mites under control, but we're rotating in other treatments as well, and we don't have high levels of resistance, if somebody buys a nuc from some knucklehead 12 states over who's willing to drive it all the way over to their customer, now suddenly, there's a possibility that the mites inside that hive are going to start spreading in the local population.

A bee drifts in the wrong direction, maybe a drone goes to the drone congregation area, gets a little confused, and he follows his new buddy home instead of the hive he's supposed to go to. Maybe there's a mite riding on his back. There's all sorts of ways that we know that these mites are able to spread. It only takes one mite with the wrong genes getting into a new hive. Suddenly, we've been able to spread something that we really didn't want spreading, like amitraz resistance, across a landscape.

Again, it's not to say that you can't have a population of bees and mites that are pretty darned treatable, where you can keep the mites pretty well under control with Apivar. The problem is that there's no guarantees anymore, because we know that this resistance can exist and does sometimes exist, and so you do need to be constantly monitoring your mite levels while you're doing your treatment. That's really true for any mite aside. If we know that we've got these devastating parasites in our bees, and we know that we need to put a treatment in because the devastating parasite levels have gotten too high, we can't just put the treatment in, pat ourselves on the back, and assume that everything's fine.

You've got to go back in and make sure that whatever treatment you use is actually having the effects that you intended. If not, you've got to grab a different one off the shelf and start that treatment instead.

Jeff: We'll be covering all of IPM in a future short.

David: Yes.

Becky: I do want to say, just because I hear what you're saying about amitraz and commercial beekeepers, but commercial beekeepers are some of the best for monitoring-

David: Yes. That's true.

Becky: -varroa and just being so just very on a schedule, and making sure that they know what their mite numbers look like in all their colonies, and figure out if requeening is needed or an intervention is needed.

David: That is a really good point.

Becky: They are some of the best as far as that control and treatment, and tracking.

David: Yes, that is a really good point, because I think that the hobbyist maybe can more easily pay attention and pay a bunch of money for different treatments for their hive, but the commercial beekeeper's livelihood depends upon staying on top of this. A hobbyist can lose their bees to varroa every single year for a decade, and they'll just keep buying more bees. A commercial beekeeper can't afford to do that. They've got to keep their bees alive. That's everything to them. You're right that good, responsible farmers are always on top of their pests, and most commercial beekeepers are good, responsible farmers who are staying on top of things.

Becky: Also, if you get a swarm, if you buy a package, if you buy a nuc from anybody, even a responsible vendor you've never had a problem with, assume they have varroa. Test for Varroa. If you're newer, you might not be good at it yet, but make sure that you're-

David: Practice makes perfect.

Becky: -going down that path. It's so hard for everybody to keep it out of their colonies.

David: Right.

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