Molly Quade: Fighting Varroa with Fungi (360)

360 - Molly Quade: Fighting Varroa with Fungi

Susanna Capelouto: Hello. This is Susanna Capelouto. I'm a proud member of the Metro Atlanta Beekeepers Association, also the Coastal Empire Beekeepers Association in Savannah, and the Georgia Beekeepers Association. I want to encourage every beekeeper out there to join your local club or two or three or more. You're listening to Beekeeping Today.

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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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Jeff: Hey. A quick shout-out to Betterbee and all of our sponsors whose support allows us to bring you this podcast each week without resorting to a fee-based subscription. We don't want that, and we know you don't either. Be sure to check out all of our content on the website. There, you can read up on all of our guests, read our blog on the various aspects and observations about beekeeping, search for, download, and listen to over 300 past episodes, read episode transcripts, leave comments and feedback on each episode, and check on podcast specials from our sponsors. You can find it all at www.beekeepingtoday.com. Thank you, Susanna, for that wonderful opening from down in Georgia.

Becky: I love it. She opened the podcast for us, and then she also had a service message for beekeepers, getting them to join not just one, but I think she was up to three beekeeping organizations, so a public service announcement for beekeepers. What a lovely way to open the podcast.

Jeff: With the chorus of her bees supporting her.

Becky: Oh, yes.

Jeff: Wasn't that fun?

Becky: That was even better. I love that.

Jeff: Thank you, Susanna. Becky, it's the end of November. How are your bees doing? What are they doing?

Becky: What are they doing? Hopefully, the goal is not much. Hopefully, they're not trying to figure out how to get themselves fed. I am just wrapping up wrapping up, which is exciting. I always put moisture boards on really early, but I am just finishing up getting some form of a winter wrap on the girls. I just go around, and I'm hefting them, making sure that there hasn't been a dramatic weight change from the last visit until now. They're clustering because our days are definitely cooler now. I was going to ask you about your bees, Jeff.

Jeff: Oh, my bees. The bees that are doing well are doing really well. I have a couple of weak colonies that will not make it through the winter. I've elected not to try to combine them or do anything. I'm just going to let them pass on.

Becky: You're not going to hold their hand. I always like, "Okay, wait, this one shouldn't make it through the winter, but let's get it through the winter." You have to have a mild winter in order to be able to hold their hand through it.

Jeff: Open them up and need just a few bees or a half frame of bees or something like that, and sit there and say-

Becky: Oh, they're not going to make it.

Jeff: -I'm sorry, girls, and I close them up quietly.

Becky: Yes, half a frame of bees now. Say thank you for your service. I've seen pretty small clusters, but that still means a strong five, six frames of bees clustered so that if it warmed up, you're still spanning more in a deep box, make it through. Honestly, the next couple of months are, December's not as challenging as January and Minnesota, and that can really, really get them to have to give up. If the cluster is not big enough to get them to that next frame of honey, then they really just don't have that option.

Jeff: Well, it's funny that we're talking about making it through the winter and winter inspections. We have a new question come in today, or come in recently from a Jeremiah Mast from Ohio, and he submitted it for our HiveIQ hive tool giveaway question.

Becky: I always love a question from Ohio. I really want to hear what he has to ask us. Can you play it for us?

Jeff: Let's queue it up right now.

Jeremiah Mast: Hi, Jeff and Becky. I just got started in beekeeping this past spring after catching two local swarms in beehives. I did the Formic Pro treatment for Varroa, and now I'm wondering here in Ohio, when's the right time to check on bees in the winter without bothering the cluster too much? If they do run low on food, what's the best emergency feed to give them?

Jeff: See, it was quite the timely topic for our initial conversation.

Becky: I have about three answers to this question. How many answers do you have?

Jeff: I have one, two. Go ahead. Go with your answers.

Becky: Well, I was always taught that you should wrap your colonies up, and then you really should not get back into them until, wow, warm, warm day in February. That means that they're actually doing a little bit of flying. I will say I really don't like that approach because if there's a chance-- I was also taught to not put fondant on a colony. I was taught that you just leave them with enough honey. That's a great idea in practice, but if something goes wrong and that cluster doesn't have access to food, but you could have emergency food on the colony, then that's fantastic. Let's go ahead and give them a chance to live. I would say that knowing how heavy they are, I always heft the boxes to see--

Jeff: I heft them all, and they're on scales.

Becky: You're a little fancier than I am. I'm lifting them up, and so I know if a colony is light going in, and so I'll make a note of that. As far as inspections go, we really do not want to break that propolis seal. We don't want to open them up because if we're doing it, we're doing it because we love to see them and we're curious. Really, if we want to help them out, hefting the box, if it is unusually light, then that's, I think, the only reason to go in there and put on some fondant.

Jeff: I agree with you. I try not to open them at all. Once they're sealed up for the winter, I do not open them. Around here in Washington state, we might get some 50-degree days in January, then I go out to the yard if there are bees flying or if they're clearing out the entrances or something, I might crack a top just to peek in on them and see if there's anything they need. That's really more my own personal curiosity and nib nosing, if you will, than it is the bees really needing anything. I like to leave enough honey on them in the fall.

Becky: That 50 degrees is a great number because if you do that and then the colonies get time, if they're big enough, that's just not going to greatly impact them. Going in, if it's 30 or below freezing, and just to check on them, is probably not a good practice. If you do think that they're potentially on the brink of starving, then that's a good time to get food on there. A lot of beekeepers will go ahead and put that emergency food on now instead of later, so that that cluster can move up into that fondant when they need it instead of you having to open up the colony and put it on when it's there. That might be the answer. Instead of going in and peeking, go ahead and just maybe give them some insurance if they're not heavy enough.

Jeff: Thank you, Jeremiah, for that question. I hope we were able to answer that for you. You will be receiving a HiveIQ tool that's been co-branded with Beekeeping Today Podcast, brought to you by HiveIQ. They are designers of innovative beekeeping equipment out of Australia. Check out all their information on our website and on their website. Thank you, Jeremiah.

Becky: Yes, thank you.

Jeff: Becky, do you like mushrooms?

Becky: I don't have a problem with mushrooms, but I don't grow them actively. I don't seek them out, but if they come shipped to my door in a box for me to make a meal with them, I certainly go for it and use them. What about you, Jeff?

Jeff: No, I don't like mushrooms, quite honestly.

Becky: That's a thing with people, because if you think too much about what you're eating--

Jeff: Actually, quite honestly, if they're chopped up fine, I like them. There's a time when the big mushroom sandwiches, instead of a hamburger or something like that, with the rage, and it's just like, "No, I can't do that." Well, a long way to get into this topic, but today's guest is Molly Quade, who is a graduate student at Washington State University working with fungus as a means to treat for Varroa in a beehive.

Becky: That is an exciting topic, and I really look forward to talking to Molly about this.

Jeff: The whole mushroom thing has been a big part of the Washington State University for many years, starting, I think, or at least made notoriety with Paul Stamets years ago and all of his research on mushrooms, not only just for bees, but for all sorts of purposes. Molly and her team are working with fungus as a means to manage Varroa in a honeybee colony. I look forward to talking to her and finding out exactly how they're doing this.

Becky: Fantastic.

Jeff: We'll be talking to Molly right after these words from our sponsors.

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Jeff: Hey, everybody. Welcome back. Sitting around the great big virtual Beekeeping Today Podcast table, we have sitting just over the mountains in Pullman, Washington, is Molly Quade from Washington State University, a graduate student, and in St. Paul, we have Becky. Hi, Becky.

Becky: Hello. Can you two hear me over there in Washington? [laughs]

Jeff: We can, we can.

Molly Quade: Obviously, yes.

Becky: Welcome to the podcast, Molly. We are so excited that you decided to join us.

Molly Quade: Thanks so much for having me on. This is so great.

Jeff: We're going to get into the meat of the discussion here real quick, but why don't you let our listeners know a little bit about yourself and what got you interested in bees and insects, and then we'll dive into fungi.

Molly Quade: Well, I originally started working here in Brandon Hopkins Lab doing honeybee research as an undergraduate back in 2021. That was when I was attending WSU here as an undergrad, doing all my undergraduate courses. At the time, I didn't have any knowledge about bees or really about research either. This was how I first got introduced to both of those concepts.

Working in research as an undergrad, I learned that I do want to do research, but what I'm truly passionate about is fungi. I spent a long time looking for programs that would be interesting for me to be a mycologist and go pursue grad school studying mycology, which is usually grouped under plant pathology, so I was looking for plant pathology programs.

I ended up deciding to stay here and continue living in Pullman and do grad school here because I had this awesome opportunity to combine the worlds of entomology and mycology and work on these different projects that were basically examining the effects of fungus on bees or on Varroa mites. There's a few different things we've done with that.

That was how I got into the bee world, was through this route of research. While fungi is really what I was originally so passionate about, now I feel like they're both such prominent things in my heart. [chuckles] It's really interesting. The more I learn, the more I learn that there's so much overlap between entomology and fungi in general. That was how I ended up here. [chuckles]

Jeff: Quite honestly, I wouldn't have thought that there was so much interconnection between the entomology and fungi and fungi-ology. [chuckles]

Molly Quade: Totally. Even just in ecology, there's so much symbiotic relationships between different insects and fungi that a lot of people might not know about, but they're very interdependent in some situations.

Jeff Ott WSU has a big program in mushrooms, [chuckles] don't they?

Molly Quade: Not really. We do have a fungarium, which is this big collection of dehydrated specimens. Other than that, we have a plant pathology department here. This is similar, I think, for a lot of plant pathology departments at different universities. They're really looking at pathogens for plants, like fungi that fall under that category. Here at WSU, we don't have any researchers who are really doing stuff with mushrooms and more stuff that's just generally interesting fungi-related, but there is a big plant pathology program that looks at fungal pathogens towards plants.

Jeff: Let's talk about, how does this relate to the honeybee now. You're starting to see a lot of connections and a lot of interplay between fungi and honeybees, and you mentioned varroa, which is our big problem in beekeeping right now. Introduce us to that topic and get us up to speed real quick.

Molly Quade: Well, at least a lot of beekeepers are familiar with the fact that we have this impending problem with the varroa mites, where they built resistance to all the miticides that people are currently using. We are in rapid need of not only new treatment methods for varroa mites but also some kind of treatment strategies that could maybe be more sustainable long-term.

We know right now that resistance is a big concern with varroa mites, that they have built resistance to many of the different miticides that are available, and so a lot of research going on in the bee world is simply looking to find new, different treatment methods or new things that could be applied to hives to kill these mites. Currently, there are no biological controls for varroa mites. A biological control is something that's used pretty commonly throughout agriculture. Essentially, it's just using a biological organism to manage the population of an unwanted pest organism.

I say manage; it's the nice way of saying we want it to kill the pests, but we say manage the population because, realistically, we know we can't control a population. Essentially, my research is looking at using this fungus that naturally kills and parasitizes insects as potentially developing it to be the first biological control for varroa mites.

Jeff: What kind of fungi attack insects, and how did they isolate it into something that would attack the varroa only?

Molly Quade: Something that really blew my mind when I first started learning about all this was that entomopathogenic fungi, which are the fungi we're talking about, entomo meaning insect or arthropod, and then pathogenic, meaning it's a pathogenic kills them. Entomopathogenic fungi are actually found very prevalently throughout soil all over the world. Basically, in every climate except for extremely cold climates like in Antarctica.

Researchers have done soil surveys all over in all the other continents other than Antarctica, and they've observed that there's a huge diversity of fungi found in the soil in general, which we already know, but there can be a multitude of entomopathogenic fungi in the soil anywhere all the time. These entomopathogenic fungi are very diverse, and they didn't all evolve together. What I mean by that is that you can find entomopathogenic fungi in many different clades of the fungal kingdom.

There are many different species, in general, of fungi that perform this life cycle, where they're parasitizing insects and killing them. It's actually a lot more common than I think people realize that they exist. Usually, people hear about cordyceps as the main one, I think, because there's a lot of stuff in the media that's proliferated the idea of cordyceps is the zombie fungus, but there's really a multitude of other fungi that do the exact same thing.

Jeff: Became a job of somebody to try to isolate those that would attach themselves literally or figuratively to the different varroa mites or different mites?

Molly Quade: I'll back up a second. Before I explain how this plays a role with the mites, I just want to explain a little bit of how these fungi are used already in agriculture. In entomopathogenic fungus, most of them anyway, they perform a very similar lifecycle where they start as a spore that is being dispersed.

If this spore finds its way back into the soil, it can maintain a saprophytic lifecycle, which means it's feeding on decaying or decomposing organic matter in the soil, but if that one singular spore ends up on the cuticle of an insect, it will start performing all these different actions that essentially allow it to penetrate the insect's cuticle, the insect's exoskeleton, and then grow within the insect's hemocoel, which is the insect's body cavity.

Point being, if there's one thing to take away from this, the spores are the unit that we care about here. They're the thing that performs that infective lifecycle. You could grow a whole bunch of mycelium from this fungus, which mycelium is just the vegetative growth from a fungus, and you could put that mycelium all over an insect, and it wouldn't do anything.

Whenever people are working with these fungi as biological controls for insect pests, they are working with the spores. Usually, in most cases, on a commercial scale, these spores are either getting mixed in with some kind of carrier powder to help it adhere to things or, like a curative solution,` if it's being applied in a liquid form. Usually, then that liquid or powder treatment is either being applied directly onto plant foliage so that any insect pests that could be feeding on that foliage would come in contact with spores, or they're tilled into the soil in order to boost that natural population of fungi that might already be present there.

To put that into context, these fungi already are used throughout agriculture, however, everybody thinks, "Okay, well then let's use them for varroa mites." The main thing that is limiting with that is temperature. Currently, my research is working with developing thermally tolerant strains of Metarhizium and other entomopathogenic fungi so that they are able to germinate and carry out this infective lifecycle in a beehive, which is much warmer than the soil outside where these fungi would naturally be found.

There is currently no large-scale use of this fungus for managing mites. It's all experimental at this time. Keeping that in mind, if this was just another insect, we would know that we can already go treat for that insect using the fungi, but because the beehive is such a different climate that they're regulating to be warm and dry, that's the main bottlenecking issue here with using Metarhizium and other fungi for that purpose. That's where my project comes into play.

Becky: When you are talking about the fungi, are these species specific? Are they actually targeting a specific beetle or a specific fly, or when they're being used-- I'm assuming they're just not a broad spectrum, is that correct?

Molly Quade: Well, it's different. It's very variable depending on the species or genus. I talk a lot about Metarhizium because that's the main fungus that is being researched for this purpose. Metarhizium is a genus. There's many different species of Metarhizium, and within that, there's some species of Metarhizium that are very, very generalist, meaning they will infect a wide variety of types of insect or species of insects. Then there's some species of Metarhizium that are very specialist. They're only going to infect one specific type of insect.

It really is variable depending on exactly what species and genus you're talking about, but because I wanted to eventually select something that would be varroa mite-specific, that's part of the cool. Other than developing thermal tolerance, I also would want to, over time, have something that is specific towards varroa mites, ideally. With that in mind, I pre-selected species of fungi that I know are already very generalists so that I could have that option versus starting with something that would only affect beetles or something.

Becky: I hear beekeepers saying, "Hey, we're trying to keep chalkbrood out of our colonies. Molly, what are you doing? [laughs] You're trying to put a fungus back into the colonies.

[laughter]

Molly Quade: Yes, and to be honest, I don't know much about chalkbrood's growth, to be honest. That's not my area. I will say with people wondering how active this fungus will be in the hive, because we would be dispersing spores specifically, which would be growing on the mites. I don't foresee this fungus proliferating very much throughout the hive. I don't see any potential of it, for example, growing throughout the wood in the hive or anything like that. For that reason, I'm not too worried about anybody having any lasting Metarhizium populations or anything like that in their colony.

Jeff: This is a little bit too early in the conversation, but you touched on it. I'll ask, how would those spores be applied to the colony?

Molly Quade: That's a great question, and that's something we're still deciding. We're still finalizing and researching which application method is the best, but there's a variety of different kind of ways you can go about it. When I first joined this project, we were growing Metarhizium on brown rice and then waiting until it was fully covered in spores. The rice didn't even look like rice anymore. It looked all green and fuzzy because Metarhizium spores are green.

We would then weigh 400 grams of this rice into a paper bag, and then put it in the top of the hive. We'd use like a little spacer board to give an extra couple of inches. You think of this as maybe a more passive mode of application because in this case, we're relying on the bees to come in and remove this debris from their hive, and in the process get the spores all over each other and hopefully onto any mites that are crawling on them.

Then we've also worked with the ways that are more direct modes of application. For a while, we were working with using spray bottles that have spore solutions suspended in the liquid and individually spraying each frame, which obviously is not something that someone realistically would do later on, if this is a treatment people are actively using. That would take too long. That was just to get research on is spraying in a solution a good way to kill the mites? Then there's also dry forms of application, so dusting the spores into the hive from the top.

Something else we're wanting to try out is using some sort of aerosol spray to disperse spores very quickly throughout the entire hive while only needing to insert the aerosol spraying device into the entrance of the hive. The ultimate goal would be to have something like that that would be a very direct form of application where it's actively being put on all the bees and they're not having to do work to put it on themselves, but then also something that's really efficient and fast for people to use in the field on a commercial level. Because if it's something where they need to open up the hive and spend more than three minutes in there, it's probably not going to be used commercially.

Jeff: You said that there were challenges to find the right delivery and the right fungi for the climate inside a colony. I would think that would be a real tough one.

Molly Quade: Totally. Yes. First step is going to be developing this strain or strains of these different species of fungi I'm working with. We are working on application as well, but that'll definitely be a further question after that strain is developed.

Jeff: This is a great conversation. I'm really looking forward to hearing a little bit more right after these words from our sponsors.

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Becky: Welcome back, everybody. Okay, Molly, first of all, I love how much you love your subject. This is exciting. Your subjects because it's bees and fungi, but this is such a fun conversation. Could you share with us, I know that a lot of people will think of a fungus, and except for maybe putting mushrooms on their pizza, they might not understand the benefits of fungi to the natural world. Could you maybe share some specific information about the benefits of fungi to honeybees?

Molly Quade: Sure. Yes. Well, I think a lot of people are familiar with Paul Stamets over at Fungi Perfecti. He's the main mushroom guy right now, I think, in the world, it seems. His company, Fungi Perfecti, and then their sister company, Host Defense, they've developed all these different fungal extracts for humans to take as supplements. A few years back, they were interested in researching how these extracts could affect bees, with the ultimate goal of developing some kind of supplemental feeding that beekeepers could put in their feeder, in their hive, and hopefully boost the bees' immunity or whatever potential effects it could have.

I've been lucky enough to be able to work on these trials where we have 100 different cages that we've hand-made out of plastic, little cups to put bees in. We'll scoop like a half scoop of bees in each one and basically feed them these different extracts. Over time, we'll collect data on the mortality and different effects that we're seeing. With each of these trials we do, we're looking at a different thing. It's pretty broad, but WSU is known for originally, or at least our lab here at WSU is pretty well-known at this point for putting out a paper that was documenting the effects on these bees, specifically the effects of viral loads within the bees after taking these extracts.

If you look at the paper, you'll be able to see these beautiful graphs that really illustrate it nicely. Basically, two of the four different types of fungi that were tested were able to reduce viral loads in these live colonies and in the cage trials as well. It was measured with deformed wing virus and Lake Sinai virus. That was pretty insightful. As far as I know, I think they're still working on getting FDA approval for this as a product. Not yet a product for beekeepers to actively purchase and use. That's the goal that they're working on. I actually just wrapped up a cage study with these extracts just recently, so I know it's still in the works for sure.

Becky: You've got a fungal pipeline of bee solution.

Jeff: How was that applied?

Molly Quade: This was an extract that was made and then poured into the feeder. I want to say it was mixed in with the sugar syrup. This was something made for the bees to consume, which is a lot different than all this other fungal work I was talking about, where it's killing an insect from the outside, so completely different. This is one that we're wanting to allow the bees to ingest, and then it's naturally priming their immune system. Just like how we know in humans, some fungi can do that as well, like Turkey tail and reishi mushroom. That was the idea behind it.

Becky: Is there any danger if you study fungi to become allergic to your fungus? I know it's common in entomologists to become allergic to their insects, but.

Molly Quade: That's a good question. I don't know a ton about that, but I will say people do worry a lot about if you're handling entomopathogenic fungi, they can somehow infect humans too. My go-to response with that is no, because our skin is a lot different, but you can develop an allergic reaction type reaction from breathing dry spores of any kind.

Something about Metarhizium, specifically, is that it produces spores very heavily, and so I'll have an agar plate with just absolute layer of green dust. If I don't open it in the hood, it'll just poof all over, and everybody will be breathing it in. That's definitely something to consider with safely handling them. As far as developing an allergy to a specific fungus, I haven't heard about that as much. That would be interesting to look into.

Becky: Well, hopefully not a personal story.

Molly Quade: Yes, maybe I'll be the first one. [laughs]

Becky: No, no, we don't want that. Varroa mites, aren't they difficult to study unless they're inside of a colony and you need to be able to see what's killing them, but if you take them out of a colony, aren't they going to die?

Molly Quade: Absolutely. That is a really great point. If this was developing a biological control for any other insect, it'd be fine because we could figure out what conditions are needed to rear that insect and we could give those conditions to them and allow them to grow and we could observe them dying. You're totally right on that. If we were to take a bunch of mites and have them in a little dish, they would all just die within, probably, 12 to 24 hours from starvation. Something we do to get around that is, we'll do these in-lab bioassays where we'll take a little centrifuge vial, a little plastic tube that holds one or two milliliters, and we'll have to work by hand, removing pupae from the cell.

Becky: Oh, wow. Oh, that's so cool. Okay, sorry, this is very cool.

Molly Quade: It takes a long time. It's one of the tasks where I'm like, "We need everybody's help today. Can we get eight people to sit around this table?" Because we'll just bring in a frame and uncap it, and then you want the pupa to be a right age. You want it to be old enough to where its eyes are just barely starting to turn purple. I'm sure you could do it with other ages, but we at least want a consistent age across the one. That's what we do. You have to very carefully remove it without damaging it in any way, where the pupa will die. Put that in the tube, and then you got your mites that you've either treated with Metarhizium or treated with a control solution, and then those go on the pupa.

Yes, with mites it's really tricky, but something else that I'm able to do to avoid having to do that whole process when I'm just working in the lab performing multiple generations of selection with these fungi for thermal tolerance, what I'll usually do, I'll have them incubated at the temperature I want them to be acclimated to. When I want to run them through a host, which you should do every few generations in order to prevent the fungus from losing virulence, because if we're just regrowing a fungus in the same plate for multiple generations, we could unintentionally select some really wimpy strain of fungus that now has no reason to infect an insect.

In the lab, when I'm doing this, something else I do instead of doing that whole thing with pupa and mite is I will take wax moth larva, that I rear, which is so funny because whenever I talk about this with beekeepers, they're like, "You're growing wax moth, why? You grow wax moth." They actually are a really, really good option for purposes like this when you need some insect host that you're rearing in a lab and you want to have it readily available. They reproduce really rapidly.

What else is really great about the wax moth specifically is they melanize really quickly. If a pathogen is starting to infect them through part of their body, that area of their body will turn black, and then over the course of several days, their whole body will turn black. That black spot will spread across their entire body.

Short answer, yes. In order to avoid having to always need mites, if I just want to confirm that this fungus still is able to infect an insect, I'll just do it on the wax moth larvae in the lab. That's especially the case now, going into the winter. Right now it's November. We won't be able to open up a hive now in Pullman for several months without risking hurting that colony and letting all the cold air into their hive. For now, I'm going to be just doing the wax moth larva now until the spring.

Becky: Oh, that's so interesting. Are you always rearing wax moth larvae, or is that just something that you did for your experiment?

Molly Quade: I originally started doing it for this experiment, which now is spanning over a year and probably will go on for the next couple of years. I basically just have some tubs put together in my lab that I-- They're pretty easy to rear. I just make sure they have food and wax to lay on, and they all go through the whole life cycle just in a tub. I can neglect them and they'll be there when I need them, which is nice.

Jeff: If you ever run out, let me know. I got some that you can have.

Becky: Yes, I think a lot of beekeepers just envision you having an old super that you're letting them tunnel through.

Molly Quade: It was nice, though, getting started with the wax moth rearing setup. It didn't work out the first couple of times, but I was able to just go get some from our apiary spot that happened to have some right then.

Jeff: How long does it take for the Metarhizium to actually infect and stop a varroa? Is that an hour thing or is that a multiple-day thing?

Molly Quade: It's going to be between 2 and 10 days for most insects. From what we've seen with mites doing these bioassays in the lab, it'll usually be between two and five days. A reason behind that, with the timing, is that this fungus is an organism that is performing this infective lifecycle in order to exploit nutrients, really. It's getting nutrition from these insects.

Thinking of it from the fungus's point of view, if you're infecting an insect host, you wouldn't want to kill it right away unless you're already proliferated, because let's say that fungus were to target the most vital organs first and that insect dies right away. Now, you, as the fungus, are having to compete with all these other different fungi and bacteria that are now also on that insect, also feeding on it as it's decomposing. It makes sense from an evolutionary standpoint why these fungi take multiple days to infect a host, because they only have been able to colonize the least vital organs first before the host insect actually dies. Short answer with that, for the varroa mites it's two to four days is what we've seen or two to six days.

Jeff: I was trying to think of how that would work into an IPM strategy or into your life cycle of the varroa mite. What's the effectiveness, and at what point would you introduce this to the varroa to be most effective?

Molly Quade: I don't know if I have much of an answer for that other than it's something we're continuing to work on, but something that comes to mind is we would want to do it whenever the mites are most exposed in the hive. Maybe timing it with the brood cycle of the colony, where it's being applied when there's most open cells available. I'm not sure exactly how you would time that, but I think a lot about that we want these spores to be getting in all the spots on bees and in the cells so that they're wherever the mites are going to be.

Jeff: After a brood break is what it sounds like.

Molly Quade: Yes, exactly. After a brood break could be a really great option.

Becky: I actually wrote down the same question. I wrote, is this to manage mites or is it to protect bees? Are you giving it to them so that, basically, is it to keep the population low, or is it to crash the mite population, if that makes sense? I think you answered that, or you're not quite there yet. I guess it's going to depend upon the efficacy and how long the spores last after you put a treatment in. Right?

Molly Quade: Right. That's also something that's still in the works, just knowing how viable is a spore. Our paper that came from our lab a couple of years ago with this, they were able to-- I don't think this made it into the actual paper, but I remember hearing that they were able to swab the top of a frame that had the fungus right on it, and they could see spores on it, and they were able to swab that onto a plate, and those spores were still viable. That was after the colony had overwintered. That might not be the case for all the spores, but you were at least able to show that, okay, some of these spores are still viable after being in the hive for three to four months.

Becky: Did they do tests for honey to see if the spores are found in surplus honey?

Molly Quade: There has not been any testing that I know of for that yet. Obviously, if a cell of honey is full of spores, you wouldn't really want that. Something else I think about is, fungi are all around us all the time. There's spores in the air, there's spores on the ground, there's a fungal biome that's in-- There's a bunch of different fungal species associated with plants, and there are pollen and nectar. That is something we definitely would want to keep in mind as we're developing this. Part of me wants to say, there's already going to be spores in the hive, regardless, to some extent. As long as we're not flooding it with spores, I'm thinking we could probably be okay.

Becky: It's one of those things where it's like, depending upon what the impact is on surplus honey might also impact what the treatment recommendations are. It might be like, okay, do this after you pull the honey, and then give the bees a year to clean up those spores, or are spores going to stick around? I'm just hoping they establish, and it's just a really low population of spores that just keep the mite populations low. Wouldn't that be great?

Molly Quade: That would be great. Something I want to try out next year is creating some frame that just has a substrate on it for the fungus to grow on. I don't know if this is exactly how this would work, but something like maybe taking a plastic frame that's just foundation, turning it on its side, and in the lab, pouring agar on it, so it's like I got this flat, big rectangular surface of agar. Then maybe growing the fungus on that. I have a feeling that agar would dry out too quick in a beehive, but something along those lines of having some frame that goes in that could maybe host the fungus as an active population. That's something I'm interested in looking into.

Becky: A fungal frame, I love it.

Jeff: A fungal frame. [laughter] Oh, Molly, this is really fascinating. The fun thing is that it's ongoing work. We can check back with you in six months, and there'll probably be more developments that you'd be able to talk to us about at that point.

Becky: Well, can we ask you, where are you in your program right now, Molly?

Molly Quade: Well, this is my second year of graduate school that just started. I originally enrolled as a master's student here, but due to the complex nature of this project-- [laughs]

Becky: Multi-year nature of your project.

Molly Quade: Yes, and due to my interest in it, I'm currently in the process of transitioning to be a PhD student. Just switching to that title in the program, meaning I wouldn't complete my master's, I would just be switching to that. For a lot of master's projects, usually everything is laid out for you already, and then you are performing the research. With something like this, it's so broad and so open, and so there's so many different routes to go that I'm having to learn so many different things on my own, which is great. I really love it. For that reason, I'm like, "I should change this to a PhD."

[laughter]

Becky: Smart.

Jeff: Is there anything you'd like to tell our listeners that we haven't asked you about yet?

Molly Quade: I want to emphasize the importance of a biological control. Because this could be the first biological control for these mites, not only is it easily integrated into organic and sustainable egg because it's a natural organism, but also biological controls usually have such a complex mode of action that it's usually much, much harder for pests to build resistance to them in the first place. Worst case scenario, this fungus could be another treatment method for beekeepers to alternate between in order to prevent resistance from continuing to grow. Best case scenario, this fungus could be a really, really effective treatment that resistance would not be built to at all.

One way to think about it would be like, if you're applying an acid or something topical to an organism, they can build resistance to that. If it's a biological organism that has evolved to have this way to be a predator or a pathogen, things don't typically build resistance to that, especially not after a few generations. It's usually many, many years of evolution to evade that predator or pathogen. For that reason, this fungus not only could be another treatment method, but it could be a really effective treatment method that mites do not build resistance from, basically.

Becky: That's so well said, Molly. Our problem has literally been that this is a relatively evolutionary new pest too, Apis mellifera, and without a lot of defenses against it, including anything in the hive that's preventing establishment. Your efforts are excellent as far as keeping our honeybees safe. Thank you.

Molly Quade: Thank you. Varroa mites are the main thing we're all thinking about right now, but also with tropilaelaps potentially in the future, this could also be a very viable option for managing that.

Becky: Molly, I think I hear beekeepers they're worried; they want you to tell them, really specifically, how is this not killing their bees?

Molly Quade: Totally. That's the main worry, is you're dumping all these spores that are insect-killing into a hive. How do we know it's not just going to kill all the bees? Especially when I talk about it being distributed onto the bees and hopefully onto any mites, why wouldn't it just kill the bees? Luckily, there's already been research showing that adult bees are very unaffected by this fungus. It's very, very hard for one of these fungi to parasitize an adult bee.

While we don't really know 100% for sure why, there's a couple of reasons that people are pretty certain about. The first reason is that bees are very fuzzy. If you ever look at a bee that's covered in pollen spores, those spores are being held away from their cuticle. It's very likely that any fungal spores that land on their fuzzy little bodies are going to be held so far away from their exoskeleton that this spore is going to send out this germination tube that tries to reach and penetrate the cuticle. That germ tube probably wouldn't reach that far.

Then the other reason is that bees are very, very hygienic. If you picture a mite with their little legs, they can't really clean things off of themselves in the same way at least that a honeybee is. That's one of their defining features is they're always cleaning each other and cleaning themselves, and cleaning their hive. We're pretty certain at this point that fungal spores that land on bees are probably getting cleaned off pretty rapidly from the bees themselves.

Becky: Are we worried about the larvae at all?

Molly Quade: We're not the only university who's working with Metarhizium for varroa mite. Luckily, there are research publications from other institutions that show when they directly inoculated larvae and pupae with a spore solution. Mind you, they opened a cell or went to a cell that was already open, and they injected a spore solution in there, so very, very intentional placement of these spores. With that, they did see a very, very low mortality rate. I don't have the number in front of me, so I don't want to quote it, but I want to say it was under 10% or 15% mortality of larvae and pupae.

There might be some concern over if the brood are being affected by this fungus, but the counterargument with that is that, if we're wiping out all the mites that are exposed in that brood cycle, a 10% or under 10% mortality of larva might be an acceptable trade-off if your colony is already strong. If it means that it's thoroughly getting into those cells and then also killing the mites that are in those cells with the larva. Again, this was in an experiment where they were directly inoculating these cells, we would not necessarily see that mortality rate if it was being applied in a live colony.

Jeff: Molly, this has been extremely fascinating, and I appreciate your time this afternoon to enlighten us and our listeners on the Metarhizium and the research that you're involved in there at WSU to see how that can affect the role of mites. Thank you for joining us.

Becky: Yes. Thank you, Molly. We are so excited to see where this takes you and where it takes the bees.

Molly Quade: Thanks so much. Thank you so much for having me. This was great.

[music]

Jeff: I was pretty happy because by the time Molly was done, I'm able to say Metarhizium and not stumble over it.

Becky: I know. I was really impressed when you threw that word out there. [laughter] I'm just like, "Jeff's got this. We know what Jeff's new side gig's going to be. He's going to be growing mushrooms someplace."

Jeff: I'm just going to throw out the word Metarhizium any chance I get just to say it. I'm really excited about this. In the last month or two, we've talked about Norroa, and now we're talking about the Metarhizium and the varroa treatment. There's the first one.

Becky: Wait, what'd you say? I'm sorry. I didn't catch that.

Jeff: Metarhizium.

Becky: Oh, okay. The Metarhizium.

Jeff: We have these new treatment or management options that are coming out, that are being developed. That might give us some hope in the future and get us out of these dreary, dreadful varroa days.

Becky: The days of varroa. You know what I'm excited about? I am excited about really smart, enthusiastic graduate students who are just working really hard to help our bees stay healthy. That's what I'm excited about. What a pleasure to meet Molly.

Jeff: If only she had a little bit more enthusiasm.

Becky: Right, right, right. [crosstalk]. She was a little quiet. No. She was just fantastic and to be only a couple of years into a program and to be able to-- Just she has so much knowledge about her subject. To be able to convey that information so well to the two of us and maybe a few other people out there, it's pretty exciting.

Speaker: That about wraps it up for this episode of Beekeeping Today. Before we go, be sure to follow us and leave us a five-star rating on Apple Podcast or wherever you stream the show. Even better, write a quick review to help other beekeepers discover what you enjoy. You can get there directly from our website by clicking on the reviews tab on the top of any page.

We want to thank Betterbee, our presenting sponsor, for their ongoing support of the podcast. We also appreciate our longtime sponsors, Global Patties, Strong Microbials, Bee Smart Designs, and Northern Bee Books for their support in bringing you each week's episode. Most importantly, thank you for listening and spending time with us. If you have any questions or feedback, just head over to our website and drop us a note. We'd love to hear from you. Thanks again, everybody.

Jeff: Metarhizium

Becky: [laughs]

[00:51:48] [END OF AUDIO]