228 - Rinkevich - Are varroa resistant to amitraz? (in English)

Andony Melathopoulos: [00:00:00] If you are a beekeeper, Or if you know of a beekeeper or if you just have a passing familiarity with beekeeping, you know that the biggest challenge to keeping honeybees alive in North America is this small reddish brown parasitic mite called the varroa mite. . Now, these mites are largely managed, their populations rebound every year and they, you can't get rid of them.

And they largely are managed with a single product and a cara side, a pesticide specific to mites with the active ingredient. amitraz. Now, amitraz based products have been around in beekeeping since the mid 1980s when they were first introduced to manage another mite, the tracheal mite. But they have stood this test of time and for a long time they've been a stalwart, especially in the commercial beekeeping sector for controlling these mites.

Now, there are indications that this product is starting to fail, which. Big concern across [00:01:00] North America, and that's where I'm so glad to have caught up with my next guest. Frank renov is a research entomologist at the Honeybee Breeding Genetics and Physiology Research Lab in Baton Rouge, Louisiana.

We caught up at the Alberta Beekeepers Commission meeting that took place in early December to talk about new research findings looking at monitor. For resistance TOAs across North America. So in this episode, you're gonna learn a lot about how to monitor for resistance and there are also some tips, especially here in the Pacific Northwest, for how you can participate in this national monitoring system so that we can get a better sense of whether these products still work and and what to do if they're not.

Here in the Pacific Northwest. So without further ado, let's talk with Frank Rink in in very cold Alberta this week on pollination.

All right, [00:02:00] welcome to pollination. I'm glad to be

Frank Rinkevich: here. This is

Andony Melathopoulos: exciting. Yeah, we are in frozen Alberta at the moment. Very cold. It's very cold. But but you were talking on a very hot topic. I know the beekeepers here in Alberta were very keen to hear of work happening at USDA Looking at the de the question of whether the stalwart product that, all beekeepers on the continent rely on amitraz.

Whether there's resistance developing. Can you tell us a little bit about where the concerns arose around amitraz resistance? One of the

Frank Rinkevich: nice things about working for the USDA is that we have a lot of stakeholder support and I get to talk to a lot of 'em. And whenever they come by the lab, I kept on hearing the same thing.

They kept on saying amitraz doesn't work like it used to. And we have to apply more of it. And in the back of my head, I started having these convers. The idea that resistance is in these varroa to explain those inefficiencies. So we actually started this project in 2019 and we went around the country and looked forage resistance in varroa.

And we found a a few pockets of it here and there, but it [00:03:00] seemed to be isolated. But then every year afterwards, where we started to do more of the sampling, we started to find more and more of it. . And in fact, this past year where we looked at over 700 samples, about half of those had high levels of amitaz resistance in our test.

And it's actually so high in our test that it will lead to treatment failure at the colony level. So this is quite the concern for the domestic beekeeping industry because amitraz is the most widely used miticide. In the United States. Now, that being said is if we lose the effectiveness of amitraz to control varroa, it's gonna be very difficult for beekeepers to manage varroa, especially in large operations where efficiency is very important.

So we're trying to document how prevalent is amitraz as resistance, but then also provide solutions. So what can we do to control those amitraz resistant varroa? And what's interesting is here in the Canadian situation is that this year other people have been finding very similar things with high levels of amitraz as [00:04:00] resistance in their varroa.

So it's a issue. In both United States and Canada. And so this week's meeting really gave me the opportunity to talk to people to extend that message and do more research so we could serve the beekeeping industry better.

Andony Melathopoulos: How does, how, just a basic question, how does one even measure? AOA looks like a varroa.

They don't, if it's resistance or not, doesn't like glow green or something. How does one. How do you test, how do you evaluate in a colony if the has a resistant population? Mites? The way that we test for

Frank Rinkevich: resistance is we have what I call the Apivar resistance test, and Apivar is the registered product that contains amitraz.

And with that test is I'll take a scoop of bees, which is about 300 bees, and we put it into a container with a little tiny square of this ape of our strip. Okay? And then we see how many of those varroa fall off the bees in three hours when exposed to that strip. Because we know at three hours, a hundred percent [00:05:00] of susceptible varroawill fall off.

Oh,

Andony Melathopoulos: lemme get this straight. So if you put the bees in this cage with that and you know they're susceptible, that you, they'll just, they'll fall off. They'll be dead. Yeah. Okay. All right. Within three hours. That's by

three

Frank Rinkevich: hours. Okay. So by def, by that definition, , any row is still left on the bees after that three hour exposure are gonna be resistant.

Gotcha. And so what we do is after that three hour exposure, we then wash those bees just with the simple detergent, and we then count the number of rows left on the bees after three hours, and then amount of bees that have varroa on them after three hours. That's what we use to determine our resistance level.

So if there's. 10 total varroa in our sample and five of them came off the bees at the end of the test, five divided by 10 is 50%, and that's how we calculate our apivar resistance level. It's a very simple calculation. Gotcha. There is much more complicated calculations we can do. , but I like to make it simple so that way we could put this tool in the [00:06:00] people outside of the scientific

Andony Melathopoulos: community.

Now bee colonies are spread far and wide. I imagine one question one might have is whether, know, maybe there's a pocket of resistance in New England and not somewhere else or whatever. How on earth are you able to perform this test across a continent of bees? That seems like a daunting task.

Yeah.

Frank Rinkevich: Unfortunately we can't be all places at all times, so what we've developed is what I call the Amitraz Resistance Monitoring Network, and it's a collaborative network of. USDA scientists, university researchers, apiary inspectors, and even beekeepers which participate in this monitoring program.

And the way that it works is that I will send them a kit in the mail, which is very easy to do and free of charge if everybody wants to participate. I send them the materials, the protocol, a data sheet, and then there's also a YouTube video of the protocol. Great. That allows people who've never done this before to see what's involved.

And that's one way we could extend our network is by having people across the country doing this test [00:07:00] remotely. And in fact, that came out of the restrictions on travel imposed by Covid. So that changed my research for the better that I was able to utilize shipping to have people do this test across the country.

In addition to that, I also like to travel a lot so I could get out in August and spend two, three weeks on the road to do the sampling. , every year we double our sampling effort. So like this, for this year, we did about 700 samples with some more data coming in soon. So it's a very popular project because of the implications it has for the beekeeping

Andony Melathopoulos: community.

Wonderful. And I do remember it is really remarkable because having this network of people, but I also, there was a slide with you and your technician. It was like 11. Almost midnight in your processing sample somewhere in a hotel room. .

Frank Rinkevich: Yeah, so some of our apiaries are quite far apart.

And then for strategic reasons, we try to drive a lot at night. Unfortunately, that means we check into our hotel at seven and we still have to process sample. So yeah, we'll be up till midnight working 1820 hour days here and there. [00:08:00] Not every day, but . Every now and then we catch a late night. So it's it, the project is exciting and for me it's, I'll step till one, two in the morning to do it because it's just it's a, it's an interesting project.

The beekeepers are interested in it and the implications it has is really motivating. And when I could tell the beekeepers about their situation, whether it's that they have susceptible, amitraz susceptible, or amitraz resistant varroa. It's a, it opens up a dialogue on what we can do, what's best for the bees.

So that's its own

Andony Melathopoulos: reward. Excellent. Well, We'll have in the show notes how people could participate. I know in the I remember one of the graphs, the Pacific Northwest , it would be nice to get some more coverage in our region in your. In this network. So we'll put that in the show notes and hopefully we can get some more submissions from our region.

Frank Rinkevich: Yeah as of today, we don't have any samples from Oregon, so it'd be great to have a lot more from Oregon. So yeah, the way that it works is you just send me your address, I send you a kit with the instructions, the materials. And there's also YouTube video, as I mentioned. And if you have any questions about it, you could email me and to get the data.

So yeah, [00:09:00] it's hope to work with some orient beekeeper

Andony Melathopoulos: soon. One of the fascinating things that you talked about in your in your presentation was following yards over consecutive years, especially with the rotation into oxalic acid. Can you explain what the fi, what you know, what was done there and what your findings were?

Cause I, I found them re I think everybody in the audience found them really remarkable.

Frank Rinkevich: Yeah. So fortunately if these varroa are resistant to amitraz, they're very likely to be susceptible to some other miticide. And with oxalic acid, the way that came about is that when a beekeeper who had amitraz resistant ROA asked me what to do, I couldn't make a recommendation cause I didn't have any data.

And so that hesitancy, I said whatever you do, let's follow up with that to see what happens. And this in these few situations I mentioned in my talk yesterday, is these beekeepers applied oxalic acid vapor every five days for four weeks, the proper treatment and the proper dosages. [00:10:00] and when we followed up with them the following year, what was very impressive was that the row that we sampled that following year, almost all those row were amitraz susceptible the following year.

I think what's happening is that the oxalic acid goes in and eliminates Theas resistant roa. And then the following spring, those row populations are founded by amitrazs susceptible row. So then as they develop over the summer when we got, when we finally test them late in August, they are mostly susceptible.

So I think what happens is we undergo bottleneck and then the populations the following year are established through founder effect with small populations. And that's how we

Andony Melathopoulos: get. . Lemme get this straight. Yes. Just so you had these apres, you tested them. , you did the test and you put 'em in the Cajuns, with Theas and not a lot of mites fell.

. Then the beekeeper went in and treated with oxalic acid, the mite levels, eventually rose up again. You sampled the. Those bees, you put that little strip of [00:11:00] AMR in the cage and then suddenly all the mites had fallen. It indicated that it was now it was you, in some ways, the amitraz might work in that situation.

Frank Rinkevich: Yeah, and that's what's interesting. And what I think what's happening is I. Based on my previous research on insecticide resistance and fitness costs and things like that I don't think this was a reversion, a genetic reversion to a susceptible phenotype. Typically, that would happen over many generations in the abeesence of insecticide or miticide pressure.

And I think what happened with this study is that the oxalic acid reduced the total row populations. and then the following spring, those rural populations that started new colonies were susceptible. So I think it's just population displacement and founder effect that's driving this. I don't think

Andony Melathopoulos: it's genetic re so not clearing up the pro.

The problem still re resides in the, population of varroa and.

Frank Rinkevich: Yeah. And I think it dilutes it to a level where the resistance leos become much rarer in that population [00:12:00] after treatment with with oxalic acid. So that situation has showed that, yeah, just even rotating one year might be enough to resource susceptibility.

So rotations are a very important part of row population management. So don't rely on just one. To do your ro control. It's that rotating of the materials, which I think is really important for impeding the development of resistance and even restoring susceptible phenotypes. We need to reproduce this because it wasn't under the most scientific conditions, it was just following up with beekeepers and this, so what we're doing this year is actually testing that we are working with.

A beekeeper who hastra resistant ROA and applying oxalic acid in a few different ways, measuring its impacts on ROA levels and colony health and survivorship. And then that way we could document, okay, here is what you need to do with actual scientifically generated data. We're gonna finish that project up in February with collaboration with Jeff Williams at University of Auburn and the students, and hopefully we can have some good data to make [00:13:00] confident recommendations on how to manage these amitraz resistant pro with oxalic acid.

Andony Melathopoulos: Alright, will we look forward to those results? But maybe to conclude the interview, you ended your presentation with a sort of decision making model. Based on resistance and susceptibility and percentage of mites. Can you walk us through, it's really nice to have the picture in front of you, but can you walk us through the gist of this what current science what you of envision as a decision making aid for beekeepers who are confronted with either resistance or lack of resistance and what to do?

Frank Rinkevich: Yeah, the interesting thing about running this amitraz resistance test is that you get two pieces of data. You get your amitraz resistance level. You also get your varroa infestation level, so you're getting quantitative and qualitative data on your varroa. And what this decision matrix looks at is the intersection of those two measurements.

So we have AP of R resistance classified as low, medium, and high. And it's plotted [00:14:00] against varroa pressure, low, medium, and high. So typically with va, we say less than one rope or a hundred bees is. One to five is medium and above five row a hundred bees is high. So we look at what we are recommending in each situation.

So for example, if we have very low varroa, low, less than one total row, and very low resistance in that situation, it's telling me to discontinue, to monitor because row levels are low that you might not need to do a treatment especially if it's you have zero r. . So yeah, in that case, you're gonna, it'd probably be a good idea to to save the cost of treatment cuz you don't have an issue.

If you have a situation where you have very low Apivar resistance, but high OA pressure, that situation is telling me that you should be treating soon because you have a mite problem. But also too, based on the results of the test, is that amitraz should provide complete control. So we recommend in that situation, imminent treatment with a p r, [00:15:00] what you don't want to do is end up in a situation where you have high APA R resistance and high varroa pressure because you need to treat those bees as soon as possible.

But AAR probably won't work because of the high resistance. So using another miticide, like potentially like oxalic acid or another material is your best bet because you're just wasting your time and money by treating with. By treating those colonies that are resistant TOAs with antra containing product.

Andony Melathopoulos: Oh. So I imagine the kind of sweet point is if you do have, you have high resistance and relatively low mites, is to get in and do an Noel acid intervention just to prevent you from getting into that top quadrant of high bar with high resistance. Yeah,

Frank Rinkevich: that's exactly it. So it's the intersection of both of those parameters that.

Dictate it. And on the slide it's, it goes from green in the lower left-hand corner where you have low resistance and low OA to red in the upper right hand corner, which is high resistance and high varroa. So yeah, it's color coded that way to tell you about how concerned

Andony Melathopoulos: you should be.

[00:16:00] Thank you so much for catch catching us up on this issue that I know many people are concerned about. Thank you so much, Dr. Reich.

Frank Rinkevich: My pleasure.