Managing Varroa in Your Colonies with Dr. Kirsty Stainton (S6, E44)

S6, E44 - Managing Varroa in Your Colonies with Dr. Kirsty Stainton

Ron Skjefte: This is Ron Skjefte with Yellow Medicine Apiaries from Granite Falls in West Central Minnesota. Here I maintain 30 hives and love it because I've found beekeeping can take me down the road as far as I may want to go in any of the sciences. Becky and Jeff, why don't you crack the cover on this  Beekeeping Today Podcast episode and see where it takes us?

Jeff Ott: Welcome to  Beekeeping Today Podcast presented by Betterbee, your source for beekeeping news, information, and entertainment. I'm Jeff Ott.

Becky Masterman: I'm Becky Masterman.

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There you go, Becky. There is a Minnesota beekeeper opening the show for us. Thank you, Ron Skjefte, from Granite Falls. Do you know where Granite Falls is, Becky?

Becky: I do know where Granite Falls is, yes, but I do not know Ron. That was a generous contribution. I can hear the listeners, there's a collective sigh of relief that I will stop begging Minnesotans to do a listener open. Do you hear that? [laughs]

Jeff: Everyone's like, "Oh my goodness. Thank you, Ron Skjefte."

[laughter]

Becky: Thank you, Ron. That was excellent. Everybody, my husband's from Ohio, Kim's from Ohio. We don't have an opening from Ohio yet. At least I don't know that we do because you do have some banked, don't you?

Jeff: Yes, I do have some banked yet from January's Louisville episode. Folks who stopped by the booth and left an opening, be patient. We'll get through them, that's for sure. Becky, it's April. Most people are thinking bees, bees, bees right now, or most beekeepers are. Packages, nucs, overwinter colonies. I look forward to April with bees.

Becky: April is just I think one of the very best beekeeping months because it gives us days where we can get through the colonies and not have to worry about temperature. Not all the days here, but we certainly do have those days. It's just such a lovely beginning of the season. It's a great beginning also for another season, right?

Jeff: Baseball? [laughs] Varroa.

Becky: Varroa. Yes. We start managing Varroa more as we start managing our bees more.

Jeff: If you are just receiving your packages and/or nucs, you should be aware of them. There are different approaches you can deal with, if you have a package versus with a nuc. If you have overwintered colonies, you really need to get on top of your Varroa treatments. This leads us up to today's guest, Kirsty Stainton, who's here to talk about her book  Varroa management.

Becky: It is just the go-to guide for beekeepers. I think a lot of new beekeepers hear that they have to manage Varroa, they have to monitor Varroa. They get one slide or one elevator pitch as far as why. This is a really nice book that-- It introduces beekeepers to the reasons why and the different approaches to monitoring and managing Varroa. I love this book.

Jeff: Some listeners may be saying, "Oh my gosh, not another episode about Varroa." I honestly do empathize with our listeners who say that because every time I open a hive and I see a Varroa somewhere, I say, "Oh my gosh, not another @#$! Varroa," because they're there. It's a reality of life. You can't ignore it. Everybody's had colonies, I've had colonies who I've ignored in the summer, in the fall, and they died by the first snowfall because of Varroa. You can't underestimate the Varroa. That's why we are beating that drum so much this year.

Becky: Even if you do everything right, you can have a Varroa problem. It's a relentless season of monitoring and managing because the infestations can come from within population growth in your colony, or the Varroa can invade one way or another into your colonies. Either your bees are robbing or drifting bees. Those drones, Jeff, they do drift and they carry Varroa. The problem is that we have to keep talking about it until we are able to figure out how we can handle it and have the solution be predictable, which is not right now.

Jeff: I just want to restate that it's not just the wandering drones that bring home Varroa to the household.

Becky: [laughs]

Jeff: All right? It's not the male bee causing just the problem. It is bees robbing out failing colonies are really subject to bringing home the Varroa.

Becky: Very true. It happens both ways, both are responsible, except if the females are bringing home Varroa from a robbing adventure, at least they're bringing home some food too.

Jeff: Oh. Oh my gosh. All right, well, so we'll leave it at that. Becky, I'll leave you with the last word on that one.

Becky: [laughs]

Jeff: Let's welcome our guest, Kirsty Stainton, to the show with her book  Varroa management, published by one of our sponsors, Northern Bee Books.

[music]

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Jeff: While you're at the Strong Microbials site, make sure you click on and subscribe to The Hive, their regular newsletter full of interesting beekeeping facts and product updates. Hey, everybody, welcome back to the show. Sitting across the big virtual beekeeping today podcast table is Kirsty Stainton. She's joining us today all the way from the UK, and she's here to talk about Varroa mites and her book  Varroa management. Welcome, Kirsty.

Dr. Kirsty Stainton: Thank you very much for having me.

Becky: Yes. Welcome. I think it's Dr. Kirsty, isn't it?

Kirsty: It is.

Becky: -or Dr. Stainton?

Kirsty: Yes, totally.

Becky: You don't have that anywhere in your book. You hid that from Jeff, but I think I did a little digging.

Kirsty: Well discovered. I did get a doctorate back in, gosh, 2008, so a lifetime ago. It was my scientific credential, but these days I don't really go by that because I'm not working as a scientist anymore, but yes, it's Doctor.

Jeff: I'm surrounded by scientists. Even at home, I'm surrounded by PhDs. I feel so inadequate. All right. Sorry. Enough about me, Kirsty, thank you for joining us. We've talked quite a bit about Varroa this year, and Becky and I have mentioned this. It's an important topic for beekeepers today. You just cannot overlook it. That's why we invited you here today. Before we get going, we know you're a PhD, can you give us a little bit of your background, who you are, what you do?

Kirsty: I got my PhD, Oxford University, in molecular biology. After that, I went on to work as a postdoc. I worked on a little microorganism called Wolbachia. This infects insects. This is how I got an interest in insects and then into honey bees. Late on in my postdoc years, I thought, "I want to get into honey bees. I want to do science and honey bees." In 2016, I joined the honey bee labs in the UK called Fera. I started doing honey bee research, and I kept doing that until about two years ago when I decided to get into science communication because through that job I started giving lectures to beekeepers, writing articles.

I found that I was enjoying that more than the science, and I was getting-- I love being a scientist, but I was getting tired of being in the lab and starting to enjoy being out in the world actually talking to people. That's what I do now. I'm working full-time, working on creating and updating literature about beekeeping, giving lectures about beekeeping, and loving it.

Becky: I get the sense that you wrote this book after giving a lot of talks about Varroa because it's so well brought together of, if I'm trying to share the message of Varroa, what do beekeepers need to know? Am I right?

Kirsty: I hate to correct you, but actually, it's the other way around.

Becky: Oh, no.

Kirsty: I'm so sorry. I wrote the book for myself, and it wasn't a book. Because when I started beekeeping, I didn't start beekeeping until 2016. As you know, beekeeping is very difficult and there's lots of challenges, but I found Varroa particularly challenging to get to grips with. I was very confused about all of the different treatments, the husbandry. The one thing I did know as a scientist was I need to get on top of this.

As part of my job, I was researching it. I was reading the papers and writing it down because my memory is terrible. I was writing down all these papers and summarizing it. I thought, "I've got to write this down and keep it and come as a reference guide when I need it in the field." Then Jeremy at Northern Bee Books approached me and said, "Would you like to write a book?" I thought, "Actually, I found this little thing I've written for myself quite useful. Maybe other people would like it." That's how the book happened.

Becky: It's so user-friendly. Did you know that because of you transitioning to scientific communication? How did you do that? Because this isn't a lot of notes about papers. You do reference them, but it is very, very user-friendly.

Kirsty: I wanted to distill down the important practical points. I think as a scientist, you learn to do that because you're reading papers to design research experiments. You distill it down into a protocol, essentially. You read what you want to do and what the experiment is that you want to design. Then you write, one, add this, two, do that. I feel that's reflected in the  Varroa management book, is this just very simple, do it like this and you'll probably be okay.

Jeff: For our listeners, can I give an introduction to Varroa? Then let's talk about how you know that you have Varroa.

Kirsty: Varroa destructor is a fairly new parasite of honey bees. It was introduced in the UK in the '90s. I'm not sure about the figure for the United States. It's only been in honey bees for a matter of decades. It's a really serious parasite because of this new relationship that honey bees have with Varroa. The native host in Asia has a variety of grooming behaviors and methods to deal with Varroa mite that our honey bees, European honey bees don't have.

This mite, which infests the brood cells and parasitizes the developing brood, is a real problem in colonies of European honey bee because the bees can't manage it themselves, and you really do have to be active in your treatment against it.

Jeff: Varroa was introduced in the United States I think in the late '80s. I ran across it first in the early '90s. You had it in Minnesota. You and Florida had it first, didn't you, Becky?

Becky: Jeff, it was Wisconsin and Florida.

Jeff: Oh, Minnesota, Wisconsin. They're close, aren't they?

Becky: There's a border. There's definitely a border. It definitely was detected in Wisconsin before it was detected in Minnesota. [laughs]

Jeff: All right. My apologies to Minnesota and condolences to Wisconsin. It's been around for most beekeepers who are practicing now. It's been with them as long as they've been beekeeping like you have, Kirsty. It's just part of managing honey bees. You have to manage the Varroa mite. How do you know that you have Varroa mite? We know that there's different washes and different rolls. How else can you tell that your colony has mites?

Kirsty: You can tell by, first of all, looking in the floorboard. If you have a removable Varroa tray, you can have a look in there. That will give you an indication of mites in the colony because that represents the natural death of mites. They will drop down into that floorboard. You can get a very crude estimate of how many mites you've got. Obviously, for more accurate monitoring, you do need those alcohol washes and drone brood removal unless you've got a pretty serious condition called parasitic mite syndrome, which is what happens when the mite levels get very high in the colony.

The problem with the high mite levels in the colony is not just the effect of the mites parasitizing those developing brood, it's that those mites are actually introducing a virus. They're vectoring a virus between the pupae that is making the whole situation worse. You end up with something called parasitic mite syndrome. If you're in a bad situation, you can recognize it through the symptoms of parasitic mite syndrome.

Jeff: What are some of those symptoms?

Kirsty: Probably, first of all, you'll see some actual Varroa, which is a fairly obvious symptom. That's just the tip of the iceberg. Any Varroa you see on the bees or on the surface of the frames is the tip of the iceberg because these guys are brood parasites. They're in the brood, causing absolute mayhem. What you start to see is nibbled cappings. The workers do have some rudimentary hygienic response, so they're nibbling the cappings because they're detecting that something is going on in there. Once the Varroa infestation gets to a very high level, they start to detect that and they nibble away trying to figure out what's going on underneath.

You will end up with dead pupae. The dead pupae is actually a result of the DWV reaching very, very high levels and killing off the pupae. You end up with the standard pepper pot brood pattern. I don't know if it's the same in the US, but in the UK, we always talk about a pepper pot brood pattern being present when a disease or disorder is present. That's caused by the pupae death.

You have deformed wings of those individuals that survive infestation and they survive the deformed wing virus, except they're useless because they've got these deformed wings. They cannot function in the colony. They will die. You'll start to see cannibalism and neglected brood. You start to see these headless pupae because the bees are gnawing away at them. Things really start to break down. You can get very aggressive bees. I don't know if it's the same in the US, but in the UK, if you've got a Varroa problem, you probably know when you're approaching the colony because they're a lot more aggressive than usual.

Things really start to break down pretty quickly from there. You've got a terminal decline if you are seeing all of those symptoms.

Jeff: If you're starting to see those symptoms, you probably have a serious case of Varroa.

Becky: When you realize that your colony has parasitic mite syndrome, hopefully, the first thing that a beekeeper does is not close the hive and decide to ignore it, right? We have a problem potentially with those mites or the colony totally collapsing, and then the bees potentially being robbed and mites spreading. What do you recommend that beekeepers do besides panic or ignore it?

Kirsty: I suppose prevention is the best cure. I probably shouldn't say that, but yes, making sure you don't get to that situation. The time that you're most at risk is around July and August, because peak brood rearing of the bees is peak Varroa rearing because that's where they live, that's where they're getting nutrition. Really keeping an eye on things through June and July when you've got peak brood rearing. Then if you do, unfortunately, find you've got a serious situation, you've got the mites and you've got the DWV, you really want a very fast-acting, very effective treatment.

I know you guys have slightly different treatments in the States, and they might have different efficiencies because some products have resistance in the mites, so they're not as effective as they claim to be because of that resistance. That depends on the geographical region. I think if I was to recommend something very, very strong for treating, it would be something like formic acid at that time of year. Because if you've got resistance to the synthetic pesticides that contain things like tau-fluvalinate and amitraz, they might not work very well.

Becky: Do you recommend if somebody notices really severe signs-- Honestly, even just seeing a mite on the dorsal side of a bee is a serious sign. Do you recommend that they still monitor and measure their Varroa level before they do something?

Kirsty: I think monitoring is absolutely key with all of Varroa management. Monitoring needs to be done throughout. I think if you're seeing parasitic mite syndrome, then just get in there and treat, provided you verify that it's indeed mites causing the symptoms because there are some conditions and disorders that may have some similar symptoms to parasitic mite syndrome. Definitely, monitoring is key, and that's something that needs to be performed regularly throughout the year because each different method of monitoring that you can use depends on the time of year and what's going on in the colony.

Becky: Yes. If you look at pictures of the parasitic mite syndrome, the brood that's been uncapped, and the perforated cappings, and then you look at pictures of American foulbrood, to the untrained eye, people can get really confused. It does make sense that they need to look for those specific signs and make sure they have not the disease, but they have mites.

Jeff: One telling thing about American foulbrood is if they're to the point where you have-- What do you call it, the peppercorn, the pepper pop?

Kirsty: Pepper pot brood pattern.

Jeff: Yes. Once you get--

Becky: I love that. We're going to start using that.

Jeff: I can't say it. Pepper pop brood pattern. With American foulbrood, you can smell it. If you see that, you put your nose down on a frame, you'll know the difference real quick. I was going to ask you because you've referred to it a couple of times and I just want to make sure we discuss this. When you say you see one Varroa on a frame or one Varroa on the back of a bee, that's the tip of the iceberg. That the majority of your problem is under the cappings. Let's restate how many Varroa are generally underneath that capping. If there's Varroa in that capping, generally, how many Varroa are underneath that capping?

Kirsty: It depends how bad your infestation is. If you've got a mild infestation, there should only be one mother mite who then lays her eggs. She will lay five or six eggs, depending on how good she is, I suppose. Then the first egg will hatch into a male mite, and then all the subsequent eggs will be the female mites and they will mate with that male. Essentially, you've got a-- What's the word? I don't want to say the word incestuous situation going on, [laughter] but essentially that's what it is, but where you've got heavy infestations, they have found that you can have more than two mother mites per cell.

Then you've got really serious situation because one mite on its own is creating a wound in that pupa and drawing out the valuable fat body from that bee and having all of those other effects of vectoring viruses and so on. Two can only be worse. If it's a heavy infestation, maybe up to 50% of those brood cells can contain multiple mother Varroa mites.

Jeff: By the time that that adult bee emerges, if they're so unlucky or lucky, to the point that they do emerge, there could be five or six or more adult Varroa coming out with it, or five or six adult female Varroa mites looking for a new home in the cell next door or down the frame.

Kirsty: Yes. They can repeat that process two or three times. They can do it more than that. The average is that one mother mite will be able to repeat that process two or three times. You then get an idea of why it is that Varroa reproduces so quickly in the brood cells. Because one mother mite can have four or five daughter mites and she can go on and do it again and again, and it just gets out of hand very, very fast.

Jeff: If you're running two brood boxes or more, and you have-- I don't know. In the States, you have 20 frames of brood. It won't be full frames of brood. Let's say out of that 20 frames, you have 15 frames of brood. That's a lot of Varroa that you're raising right there along with the brood at the height of summer. That's the iceberg part of the iceberg.

Kirsty: Yes. Summer is the hardest time because you've got the supers on the hives. You've probably not got very many options for Varroa treatments. You're probably hoping that everything's going to be okay until you take those supers off and you harvest your honey, but it might not be because that's when things are really taking off for the Varroa.

Jeff: All right. Let's take this quick break to talk to our good friends at Betterbee.

[music]

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Becky: Welcome back, everybody. Kirsty, I was struck by some numbers you put in the book, where you talk about if you start a season with just 50 mites in the colony, I don't think I'm ever going to forget these numbers, what can happen in 120 days.

Kirsty: It's very sobering to see how quickly the mites can reproduce. That's only under a situation of that being an isolated colony because obviously, you've got Varroa coming in from neighboring colonies, there's drifting, robbing, and so on. The bees are picking up from all sorts of places.

Becky: Yes. If they can go from 50 to 1,000 in 120 days, if you just think about what 50 cells in your brood nest is, it's nothing. It's just so minimal. If you think about how hard it is to control the mites underneath the cappings, it really is, I think you used the word, it is sobering to think that you have that problem and you can never eliminate them from the hive. You're at a point where you're just always managing the population unless you're on some lovely island with no other bees coming into it.

Kirsty: Yes. I think that's a really difficult thing to accept actually. There's one thing about the book that I'm not sure was criticism, but people ask me why I didn't put shook swarming in there as a management tool for Varroa. I think that's a good question because you can manage Varroa by using a shook swarm. A shook swarm is commonly used, in the UK, at least, for things like foulbrood infection. What you do is you shake off all of the adult bees and you put the queen as well into a new colony with fresh foundation, and it's all clean, and you get rid of the brood. You destroy the brood.

We use it in the UK to treat European foulbrood at low levels or early on in the year because obviously, we can't do it in the autumn because you're getting rid of the brood because the brood is the source of the infection. You get rid of all of that brood and you start again, you get nice clean wax and the bees build up again. The theory is, yes, that should work for Varroa because you're getting rid of the brood. This is the general gist of any husbandry option for managing Varroa. Get rid of the brood, that's where the Varroa are.

The reason I didn't put shook swarm as an option for treatment in the book is that a shook swarm it seems like a fairly extreme measure to do on something that you have to manage all year round. People who do use shook swarms every spring report having good results because they reduce the pathogen load in their wax and any residues from pesticides and so on.

For me, I just felt it was quite an extreme way of treating or managing for Varroa when you can do a brood break and keep all that wax and maintain that energy that the colony has put in. I'm not knocking it as a method of reducing Varroa. Indeed, will reduce the Varroa, but then you've got to think if you're doing a brood break, how are you going to kill all of those mites that are still running around on the adult bees?

Becky: It's double stress. They're losing their home and then you're going to have to put some treatment on them.

Kirsty: Yes. Sometimes if you want to avoid using chemicals, I don't know about it in the US, but in the UK there's a lot of people who are advocating for avoiding treatments and avoiding chemicals, the brood break is only going to buy you a limited amount of time if all of those mites just get to run back into the brood cells once the queen gets started up again.

Jeff: Varroa has been a big topic for us. Let's skip over our specific treatment options and advise our listeners to go to Honey Bee Health Coalition for those in the States. Let's talk about some of the higher-level management options that you can help us with.

Kirsty: There are a variety of ways of managing Varroa. On one side, you've got the chemicals, you've got the products that you can add to the hive to actively kill the mites. On the other hand, you've got husbandry and management tools. In most cases, that's to stimulate a brood break so that you're getting rid of the mites that are inhabiting the brood cells, but that does not kill the mites that are on the adult bees. This is where you have to think about combining the husbandry and management tools with the chemicals.

If you're thinking about doing a brood break, for example, from queen caging, I don't know if that's popular in the States, but queen caging is a good way to stimulate a brood break. You get rid of all the brood in there, but you've still got the Varroa on the surface of the bees. Something that's absolutely fantastic for a broodless period is oxalic acid. Now, oxalic acid claims to be something like 99% effective at killing mites. Actually, is, if you read all of the papers that have been published about it, and I have.

The brilliant thing about using oxalic acid to treat Varroa is so easy. There's different ways you can do it, but the best way is to just mix it with some sugar syrup and trickle it onto the bees between the frame spaces. You can get a knockdown of over 90% of the Varroa that still remain. Combining treatments is a really clever way to get more bang for your buck when you're doing your Varroa management.

Jeff: We call it the dribble method here. I don't know if that's what you call it.

Kirsty: Trickling, we call it.

Jeff: Trickling. Dribble, trickle.

Becky: When you say combining treatments, you mean combining a chemical with a management?

Kirsty: Yes.

Becky: Correct.

Kirsty: That's what I meant to say, yes.

Becky: We don't want a lot of chemical cocktails going on in those hives.

Kirsty: No. I would like to stress not to combine treatments. I'd also like to suggest, and this is something that in the literature in the UK I felt was lacking, to draw a line between the treatments based on essential oils and organic acids and those based on synthetic pesticides. I think it's a really, really important line. I think the pesticide-based products should be avoided if possible.

I have nothing against the companies who make them. I think these products can be really effective, but they're only really effective if you don't use them very often because the mites become resistant so quickly, especially with something like tau-fluvalinate, your mites can become resistant within three years of using that if you're using it repeatedly. Things that have essential oils and organic acids like thymol or oxalic acid or formic acid are the first stop for any kind of Varroa treatment, but not a combination of those. Certainly, not one that's been verified and approved by the authorities.

In the UK that would be illegal. I don't know about it in the US. Combining those treatments with your management tools like queen caging or your brood break or whatever method you choose to use.

Jeff: What's your favorite approach for Varroa, Becky?

Becky: Oh, okay. As you did mention, oxalic is definitely one of my go-to's at certain times of year, but my favorite, favorite, favorite approach is formic acid. I treat every colony in the spring because I'm in the area where all of my colonies have mites because of the high density of honey bees, but everybody gets it in the spring, everybody gets it midsummer because the risk of invasion and the ever presence of the Varroa population is just a fact. I just love how my colonies look after using it. I'm not a spa. I'm not getting paid to say that. I literally love that treatment. It has just been a game-changer in keeping my bees healthy.

Kirsty: I'm also a fan of formic acid, but actually in the UK, it's got a bit of a bad reputation. That's because there are some caveats to using it safely. One of them is that your colony has to be more than six frames of bees and all of your entrances have to be open. It has to be very well-ventilated. I think there were some teething issues early on in the formic acid-based products in the UK, which has meant they've got a bad reputation.

I think it's not really deserved because if it is used correctly, then it should be a very effective product, and there may be some minimal death. This is something that sometimes happens with the mite treatments. You'll observe minimal death. You'll see some worker bees or maybe even some brood pulled out, for example, with thymol. I think the gut reaction is to think, "Oh, no. This treatment has done something bad to my bees," but actually, these things are accounted for. In the whole population of the colony, that's actually a negligible amount that's lost. It's worth it for the Varroa treatment because what the Varroa are doing is so much worse than any minimal effect of a chemical.

Becky: Kirsty, I just want to clarify, when you say six, do you say six frames of bees? Are you talking about in a deep box?

Kirsty: We use a standard [crosstalk]

Becky: I think we're talking different numbers. We're talking Langstroths over here.

Kirsty: Oh, okay.

Becky: For the most part.

Kirsty: I think maybe we use slightly smaller hives, which is maybe why we had a problem less so than you have because if you're using a bigger hive and you've got more bees, then you're less likely to have that accidental overdose, which is of an effective population and air.

Becky: In the US with what we have available commercially for formic acid, the smallest colony size I would use one strip in would be single deep. That's at least nine frames of bees. We're talking about the same effect of product, but I think it's being sold in different doses. My guess is that your dose is different than our dose just because of the equipment that's being used. I just want to clarify that our listeners shouldn't put a strip of formic on a nuc colony because they might see some bad effects, but yes, ventilation is so important.

Jeff: What are the bad effects of formic acid? If you go to the social media sites and you hear these horror stories of the festooning of bees out at the front once they put on the formic acid, what is the proper application, if we can just cover that real quickly, at a high level?

Kirsty: With any formic acid product, it's easy to accidentally overdose if there's an insufficient population of bees. As we said, you need a minimum of six frames of bees, and you need to make sure the entrances are open and that there's plenty of ventilation getting to the hive. If you've got the removable floor, take that tray out so that the vapors can dissipate. What happens if there's an accidental overdose is that not only can you have loss of the adult bees but you can have loss of the queens. There can be serious queen problems if formic acid is accidentally overdosed, which is why it has a bad reputation over here.

Becky: I think that when I hear about people saying they have-- I've never really experienced queen loss because of formic application, and I've used it a lot, but I think that if you're using it on a colony that is in the middle of a collapse, I am not surprised that you might lose a queen. I think if the infestation is severe enough, the formic is going to be more to prevent the mites from spreading than to save your colony necessarily because I think even if you have a populous colony but it's not operating as it should because they're sick, you might see some queen loss.

I hear from some people sometimes that they talk a lot about queen loss, but if you go through when it was finally applied, it might have just been too late to actually be a successful intervention to manage the population to keep the colony healthy.

Kirsty: That's the problem with a lot of the chemical treatments, is someone will say, "What's the best treatment for something?" You say, "Well, it could be this, but you've got a long list of things " What size is the colony? What's the temperature outside, et cetera, et cetera? Because that influences so much of how they act, and they all act very differently. It can be very confusing to get your head around all of these different factors.

Becky: It's changing, right? It's an ever-changing world out there. I think once people start to understand the problem and stop chasing the mite population instead of controlling it, I think that that makes keeping your bees alive a little bit easier. Instead of reacting to the problem, being really proactive. I think that makes people a much better Varroa manager.

Kirsty: Yes. It has to be an ongoing management throughout the year, have specific set times where you check for Varroa during your monitoring methods. This should definitely be early spring to make sure that your colony is getting off to a good start. A really key thing I actually haven't mentioned is checking around July or August, not just because you've got to think about whether your supers are present, but one of the things that Varroa does is that it parasitizes the fat body. That was discovered by Sam Ramsey, who I think you may have had on your program.

He wrote a fantastic paper about that. The repercussions of that are those bees that have had their fat bodies damaged during that time have reduced overwintering capacity. You think your bees have gotten away with it if you've treated them late, but actually, they're not going to survive the winter. That's when Varroa losses can manifest, is actually in the spring when the bees haven't been able to make it because of the damage to their fat body.

Becky: The University of Minnesota has actually shifted when they're telling beekeepers to pull those supers and intervene to an earlier date because of mite management.

Kirsty: I think that's a good recommendation. You can even put them on again afterwards, as long as you've managed those mites. I don't know if it's common in the US to put them back on for the ivy flow. We have ivy here in abundance.

Becky: I wish we had an ivy flow. That sounds so lovely.

[laughter]

Do you have an ivy flow, Jeff, in Washington?

Jeff: No. Blackberry. We have blackberry flow. Ivy, no. No, no, no.

Becky: We have goldenrod. That's our fall flow.

Jeff: What about drone removal? Is that an effective control?

Kirsty: It's actually a surprisingly effective way of getting rid of mites in that mites are particularly drawn to drones because drones are capped for longer than workers. That means that mother has more chance of reproductive success. Maybe she can make an extra mite, maybe she can be more successful if she goes to the drone brood. What happens is, if you put a frame of drone brood into a box near the brood nest on the edge of it and you trap the mites in that drone brood and get rid of it when it's capped, you can see a 50% reduction in Varroa mite.

That's from a study, so I guess it's very variable. That's from the study I could find quantifying the effects, but you could expect something like a 50% reduction in Varroa, which is fantastic for not using a chemical, but in reality that just buys you a brood cycle because they can double every brood cycle. It's useful. It's a good tool. In this country, you can do it June, July and then you don't do it beyond that, but that buys you time. It's buying your brood cycle to keep those supers on.

Jeff: At the time our listeners are listening to this episode if they're listening to it the first week it's out, many of them are getting set to receive their packages and nucs of new bees and they're getting ready to set up the new colonies, what is your recommendation for Varroa management on that brand new nuc of bees that you receive or the package? Do you have any recommendations?

Kirsty: I guess package is different from a nuc because your package bees doesn't have any brood. You can give them a little puff of oxalic acid. I don't know how many bees are in a package bee because I've never actually received them.

[laughter]

Hopefully, that's safe advice.

Jeff: We'll send you some.

[laughter]

Kirsty: I might get into trouble for that.

Becky: We can definitely dribble them, 7 to 10,000 bees.

Kirsty: With nucs, you do a reduced administration of different products. I guess you have to check it first. Hopefully, you've checked your nuc. You've made sure it's come from someone who isn't rearing Varroa and that they're actually rearing bees.

[laughter]

Then you check, you have a look at that nuc, you get a feel for what's going on. If you think there might be some Varroa in there, even in spring, even a few mites is bad news. You have to be careful with a nuc to make sure that you're not overdosing. We talk about overdosing formic acid, but you can actually overdose with thymol or the synthetic pesticides if you don't reduce the formulation. Usually, they recommend a half, but it does depend on what product you're using. That's definitely something to be mindful of with nucs. Formic acid is a no.

[laughter]

Just don't do that.

Jeff: Just say no to formic. That's always a concern for-- it should be a concern for when you receive new bees, am I receiving someone else's problems, whether package or nuc? I think it's an important consideration.

Kirsty: I think so. I've known beekeepers who have had that happen. They're new beekeepers, they're excited to get their bees, and then things aren't going the way they hoped, and they've ended up with a colony of Varroa. In one case, I've known a beekeeper who inherited some chronic bee, which was particularly nasty because she also had a lot of Varroa in her new colony as well.

Jeff: Oh. All right. This is a topic that may irritate some folks, but I do want to bring it up because it comes around all the time in every bee meeting, is the beekeeper says, "I don't need to treat for Varroa. I don't see Varroa in my bees. I have genetically hybrid bees that are good at keeping down Varroa." I've got whatever. What is your recommendation about non-treatment, non-management of bees, letting them bees be bees?

Kirsty: That's not a small question.

[laughter]

Jeff: In the next few minutes, let us know.

Kirsty: That's a huge question. When I talk about Varroa treatments, I dedicate quite a sizable portion of my lectures talking about this, just to introduce the topic, because it's such a difficult thing. If I was to try and do it briefly, I think one of the key points is mating isolation. If you're trying to breed for Varroa resistance by selecting from your colonies that haven't died after you've stopped treating, but all of your neighbors are treating, then you're not going to win, sorry.

You might think it's okay for a couple of years because sometimes the colonies can take a few years to actually fully die from Varroa. In the long term, it's not a viable strategy unless you're very geographically isolated, and that's an important point because you're always going to have an influx of alleles, and that is genes that are counteracting your resistance genes because you're in the minority.

Another thing to think about is inbreeding. If you're talking about trying to select for Varroa, the problem with Varroa is the colonies that die from it, it is going to be the majority. You're going to lose 9 out of 10 colonies from Varroa. Depending on what you're starting with, you can end up with a bit of inbreeding going on in those colonies. There's so much complexity involved in the genetics of resistance, which I'm not going to go into. It's a very complicated picture.

As a molecular biologist, I've looked at the genetics of the genes and pathways that are suspected to be involved in Varroa resistance and there's hundreds of genes. We're talking about-- You don't need all of them to be selected for resistance, but you need some proportion of those hundreds of genes to be involved in those pathways and processes for those bees to become resistant. It's just not going to happen if that doesn't happen because the genetics is the nuts and bolts of the whole thing. If you're isolated and you've got thousands of bees and there's no imports, knock yourself out. Otherwise, it's going to be very challenging.

Jeff: All right. That's a truthful, honest answer in two or three minutes. That's good.

[laughter]

Becky: It's one of the best I've heard.

[laughter]

Jeff: This is such a deep topic, and we've barely scratched the surface. Is there anything that we haven't asked you that you were prepared and just ready to talk about for the next couple of seconds? [laughs] I'll give you another two minutes.

Kirsty: Deformed wing virus. Conversations about Varroa and not treating for Varroa and treating for Varroa. Every conversation about Varroa seems to focus on Varroa, but deformed wing virus is a really, really important player in this situation. You're not just thinking about an interaction between a honey bee and a mite, you're thinking about the interaction between the honey bee and the mite and the virus.

This is endlessly complicated because I always say in my lectures, "Deformed wing virus is working for Varroa. These guys are working together." If you're thinking about non-treatment, you're not just thinking about selecting for a bee that's resistant to mite, you're thinking about how that bee is coping with high levels of deformed wing virus. I don't know if you know this, but deformed wing virus, the reason I say it's working for Varroa is that it increases the honey bee development time, so Varroa has more time to reproduce those breed cells.

Worse than that, DWV-infected bees have been found to have-- there's less of a hygienic response in the bees. The bees are less able to detect those Varroa-infested cells if there's lots of DWV. It's like the DWV is masking, it's hiding them. It's keeping them hidden in the basement underneath. In some cases where they have reported Varroa resistance in bees, what they've actually got is a population of bees that have avirulent deformed wing virus or no deformed wing virus.

It has been found, there's a mounting body of evidence, that bees that don't suffer from deformed wing virus and just don't have it present are more able to tolerate Varroa. They're tolerating it. They're not resistant, but they can tolerate a much higher load of Varroa and they can become stable in that way. It's very different when you start thinking about this third player in this horrible game between bees and the mites.

Jeff: Kirsty, this has been a very depressing conversation.

Kirsty: Sorry.

[laughter]

Jeff: No, it's been very enlightening. I hadn't heard that one part about that last key point there that you pointed out about the DWV increasing the brood time of the honey bee, giving the Varroa more time. I had not read that. That's news. That's good. Heard it here on  Beekeeping Today Podcast. Kirsty, it's been great having you on the show. I hope that you keep doing some research and continue speaking and you come back and visit us again.

Kirsty: Thank you very much. It's been my pleasure.

Becky: Thank you, Kirsty. We appreciate your visit.

[music]

Jeff: That was great having Kirsty on the show. I'm glad that you recognized her as having a PhD. That wasn't in her book, was it?

Becky: It's nowhere in her book. I remember that when I read her book and I saw how she cited all the research, I just knew she was a scientist, so I did a little bit of digging.

Jeff: Fantastic. It caught me off guard, but it was really great surprise. This would be the fifth time I've said this in this episode, we've really been beating this Varroa thing to death. It won't be the last time we've talked about it but from today's discussion with Kirsty, who's written that very good guide on Varroa management, which is the title of the book, you'll find the link to that on Amazon and from Northern Bee Books in our show notes, I don't know if we can summarize it really quick, is to have a plan for Varroa management.

Start the season, know that you're going to have to manage for it. Monitor for Varroa. Choose a method that you want to monitor and keep records of. Know your options, which options do you want? Are you going to do soft chemicals or hard chemicals? What fits your management style and your location?

Becky: Well said.

Jeff: Manage for Varroa. Manage your bees, manage the Varroa, manage your whole operation for Varroa. Know that no matter what you do, no matter how good of a beekeeper you are, you're going to lose some colonies.

Becky: That's really well said, Jeff. I think, one, your last point takes some of the shame of Varroa infestation out of it. We all get Varroa. Depending upon what your bees are doing, you might get to unmanageable numbers before colony death occurs. Also, I think those five points put together something that's really important. Nobody wants to put chemicals in their hives. Nobody wakes up and says, "Oh my gosh, for no reason at all, I'm just going to apply this to the hive and see what happens."

If you have a really good management strategy and a plan, you can decrease the amount of miticide, either organic or synthetic, that you actually need to use in your hive in order to lose as few colonies as possible. I think that those five steps, if people follow them and really take on the challenge of, let's not let these mites increase in population to the point where they're going to kill a colony, I think it can make a difference.

Jeff: All right. Thanks, Becky.

Becky: Yes. Let's go see our bees now in our respective states.

Jeff: [laughs]

Becky: It's bee season. [laughs]

Jeff: That about wraps it up for this episode. Before we go, I want to encourage our listeners to follow us and rate us five stars on Apple Podcasts wherever you download and stream the show. Even better, write a review and let other beekeepers looking for a new podcast know what you like. You can get there directly from our website by clicking on the reviews along the top of any web page.

We want to thank our regular episode sponsors, Betterbee, Global Patties, Strong Microbial, and Northern Bee Books for their generous support. Finally, and most importantly, we want to thank you the  Beekeeping Today Podcast listener for joining us on this show. Feel free to leave us questions and comments at the "Leave a Comment" section under each episode on the website. We'd love to hear from you. Thanks a lot, everybody.

[00:50:33] [END OF AUDIO]