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| All right, let’s get started! Hi, everyone! I’m Bree Price. I’m the WSU Bee Program Extension Coordinator. Thank you so much for coming to the last webinar in our 2025 webinar series.I just have a couple of announcements before we begin. The WSU Honeybees and Pollinators Program is a cornerstone of the College of Agricultural, Human, and Natural Resource Sciences, abbreviated CAHNRS, that is dedicated to fostering resilient ecosystems in Washington and beyond. Our mission intertwines innovative research, community engagement, and education to safeguard pollinators pivotal to our food security and environmental health. In partnership with the CAHNRS Resilient Washington Initiative, we’re committed to advancing sustainable practices in pollinator-friendly landscapes as well as ensuring a flourishing future for agriculture and natural resources. Today, there will be time to answer questions after the seminar. Feel free to type your questions in the Q&A box below anytime during the presentation. After the event and before you close your browser, you’ll be prompted for a short 5-question education outreach impact survey. Your participation in this really helps us tailor our education outreach to what you’re wanting to learn about. Today’s speaker is Molly Quade. Molly is a graduate student at our bee program. She began working at the bee program as an undergraduate where she assisted on a collaborative project with Paul Stamets with Fungi Perfecti, investigating the role of reishi mushroom extract in enhancing honeybee immune systems. This experience sparked her interest in insect-fungi relationships, and since then she’s contributed to a variety of projects focused on integrating fungal applications into commercial apiculture. Now, as a graduate student at WSU. Molly is researching the use of Metarhizium and other entomopathogenic fungi in integrated pest management, with a focus on developing strains for varroa mite management. She plans to continue her research in fungal strain selection with the long-term goal of advancing the application of fungi in commercial beekeeping and sustainable agriculture. This webinar will overview ongoing research, developing strains of entomopathogenic fungi to help honeybees manage varroa mites and other honeybee pests associated with beekeeping. Metarhizium an entomopathogenic fungus, is already implemented in various agricultural pest management products and could be developed into a host-specific strain for beekeepers, which would benefit both commercial and hobbyist operations. This exciting collaboration between entomology and mycology holds significant potential for modern agriculture. I’m going to mute myself and hide my video, and you can share your screen, Molly. | Woman in grey shirt on screen wearing glasses and a Washington State University Logo in the background.hyu78 |
| Awesome. Thanks so much, Bri! All right, thanks everyone for being here tonight for this webinar. I’m really excited that it seems like there’s a lot of people here excited to hear about this topic, and I’m working with strains of these fungi that could potentially be a new management strategy for Varroa mites, so I’ll go ahead and get started. | Title slide reads “Entomopathogenic Fungi for Varroa Mite Management,” over an image of fungal spores with honey bee hives. Molly appears in the upper right corner of the screen to speak. |
| A little bit about me. I worked here as an undergrad in this lab, and I originally wanted to study fungi and pursue a route of study related to mycology. And there’s a lot of different reasons why mushrooms and fungi in general are appreciated by so many people. They’re very beautiful, for one. They bring people together, people like to get together and forage together, and cook together, and they’re very tasty, they’re very nutritional, and there’s been a lot of ways that fungi have been used through advancing medical techniques or advancing agriculture. And so, it only makes sense to consider how fungi could be used to help honeybees. I ended up deciding to stay here as a grad student at WSU because I had the opportunity to explore these opportunities of how we could use fungi with bees. | Images showing multiple fungi: an Amanita muscaria mushroom, shiitake mushrooms growing in a bucket, people gathered around a basket of mushrooms, and spores under the microscope, highlighting the different interests fungi bring. Molly shows an image of beekeepers with bees to connect fungi with bees. |
| So, and surprisingly, there’s actually a lot of different research going on. That’s kind of the cross-section between mycology and apiculture, so… Here’s kind of an outline of what I’m going to cover today. I’ll give a quick little background on the stressors currently faced by bees so that you can understand how these fungi are going to play a role, and then give some background on this fungus, Metarhizium, and how it’s already used commercially. And then, the research we’ve been doing here at WSU over the last few years, and then finally, I’ll discuss my research that I’m doing, as my thesis. | The slide depicts the outline for the presentation overlaid over an image of honey bee hives with bees in the air. Molly reads the points off the slide: Quick background on stressors currently faced by honey bee colonies; Metarhizium fungi and its use within integrated pest management; Current and past research investigating use of metarhizium in apiculture; My research: Selecting thermally tolerant strains |
| So, first and foremost, we’re all familiar with, well, if you’re if you’re a beekeeper, you’re already familiar. A lot of us are familiar with honeybees and how they’re used in agriculture. They are an introduced pollinator, they’re not native to the Americas. And they’re introduced, and they’re perfect for pollination, commercially, because they nest in cavities and were able to have them in these cavities that we provide in the form of a nice beehive box.And we’re able to move them and manipulate them around as this livestock that is performing this, pollination for us that’s necessary, that cannot be done without these honeybees on such a large scale of monocultural crops, because we don’t have, population of other insects that would normally do that when we’re growing everything in these vast monocultural areas. So, because of that, we are dependent on honeybees. | Slide has image of commercial honey bee colonies in the hundreds being unloaded into an almond orchard from a large truck. Molly reads the text on the slide emphasizing the commercial importance of honey bees. |
| And that’s why there’s all this concern all of a sudden, with, recent years of honeybee mortality drastically increasing. Where we’ve been seeing higher and higher rates of colonies coming out of the winter dead, and, this data only shows up until 2022 to 2023, but this last year was actually one of the worst years on record, where commercial beekeepers were reaching out to us, the university, seeing if we had any bees to spare, like, that’s how bad it was. So, we know that there’s this rapid problem that is concerning to not just beekeepers, but to everyone, because our agriculture is dependent on this. | Slide is titled “The Problem” with an image from Bee Informed Partnership, showing how honey bee colony death is rapidly increasing each year. The most recent year in the image, 2022-23 has 48% mortality, the highest of any previous years. |
| And, of course, we know. There’s already all kinds of obstacles that honeybees naturally would have to go through. So, for example Finding a balanced diet of pollen and nectar, having a big enough population to survive through the winter. And then managing different parasites and pests. | Slide is titled “the facts” With images of honey bees with diversely colored pollen, clumped in a beehive for the winter, and different honey bee pests |
| And of course, unarguably, the main parasite here that’s an issue is the varroa mite, The reason that honeybees need, intervention from a beekeeper to help manage these mites is because originally, these mites were not parasites to Apis mellifera, they were parasites to Apis cerana, the eastern honeybee, and just in the last, like, century, couple hundred years, we’ve seen this host switch, and then… it wasn’t until the 80s that we started seeing varroa mites on Apis mellifera in the United States. So honeybees, they’re dependent on us to step in and do something to help them naturally manage this parasite. | Molly reads facts about Varroa mites from the slide with images of varroa mites. |
| And now, not only are our bees facing all of these natural obstacles they’d normally face of eating enough nutrition and maintaining a big enough population, but. They’re also facing all these other stressors that are related to modern agriculture, like how they’re being moved around and often losing a lot of foraging workforce during the day, but then, now, on top of all that, we have these mites that are vectoring disease and causing physical damage to tissues of honeybees and kind of all of this together has just been contributing to this mortality problem. | Slide reads “Compounding Problems” with an image of a honey bee surrounded by bubbles depicting the mentioned obstacles: gaining enough nutrition, loss of foraging workforce during transportation, maintaining large enough population to survive the winter, pesticides with legal side effects, managing pests, and climate change, with varroa mites stacked on top of these bubbles, vectoring disease and causing physical damage. |
| But mainly, the mites, as we’ve seen in recent years, have built resistance to, the miticides that are available for them. So there’s all these different methods of managing miticides. But… or, excuse me, managing varroa mites. , but they all have their own drawbacks, so… Of course, mechanical methods, they’re often not very reliable or can be too time-consuming to implement on a commercial level. And then synthetic miticides can build up residues in the comb and have negative long-term effects on larvae and brood over multiple generations. And then other miticides, of course, are gonna require proper PPE, but like I said, the main issue here is that mites have built resistance to these miticides. | Molly breaks down the list of Varroa Mite Management methods as text appears highlighting her points. Mechanical methods such as powdered sugar are too time consuming or not reliable . Synthetic miticides build up residues in the comb, affecting larvae and comb products. Many miticides are no longer effective due to resistance being built. |
| So, the solution would be having more options in the mix to alternate between to prevent. Resistance from building over time, because we know that pesticide resistance and miticide resistance is built when ee have, a lot of use of the same treatment over and over. Populations of an organism are able to build resistance to it quicker. So, not only do we need more methods of managing varroa mites, but it would also be good to find something that could be more sustainable and potentially be, harder for these pests to build resistance to in the first place. | Image showing how pesticide resistance is developed. A graph depicts that most of the population will die at first from a pesticide application, with few surviving. A second graph shows the following generation, where most are surviving and few are killed, because they now have more resistant genes and are less susceptible overall as a population. Text below reads “Varroa mite populations have built resistance to available miticides – new strategies are needed fast”. |
| So, that kind of brings us into this idea of biological controls. So, if you’re not familiar, a biological control is just a fancy term for using a biological organism to manage the population of another organism that we don’t want, so kind of the common example that most people know would be releasing ladybugs in the garden to manage aphids, or using a cat to manage rodents, anything like that, just using any living organism. To manage the population of an organism we don’t want. So, what’s really great about biological controls is that it’s usually harder for pests to build resistance to them, because they have such a complex biological mode of action, usually. So, sure, like, a rodent could maybe have a new strategy for evading a cat, but they’re not gonna build resistance over generations like how we would see with, something like an acid that we’re applying, or something that, is like a chemical treatment. So, finding a biological control for varroa mites could be a good route to go if we’re trying to, not have this problem anymore of long-term resistance and of course. Any organism can be a biological control, any living organism, so we have examples with insects and mammals, but also birds, bacteria, and even fungi can be biological controls. | TItle text reads: “Potential new strategy: Using a biological control” with an icon depicting insects and humans working together to manage crops. Text reads: A biological control means using a living organism to manage a population of a pest” Easily integrated into organic agriculture, low non-target toxicity, usually harder for pests to build resistance. The word “fungi” in green appears when Molly concludes points |
| So that brings us to our fungus star of the show today, Metarhizium, which is an entomopathogenic fungus, so… It is entomo pathogenic. It is pathogenic towards insects. So it parasitizes insects, and it kills them, while exploiting. Nutrients from the insect’s body and organs. , and what’s really wild about these fungi is that they’re actually present in soils all around the world, and there’s been some interesting, survey research done that has shown that. , not just Metarhizium, but entomopathogenic in general are, very, very prevalent just in soils in all climates, in all regions of the world. So, along with many other things in the soil, right? It’s all in the soil, so that’s kind of wild that to me, anyway, when I was first learning about this, I didn’t expect this to be such a common thing, these insect parasitizing fungi to be found around us all the time, but they are, and you might be thinking, well, where are all the parasitized insects? What’s really cool is that, this fungus can actually just be a saprotroph as well, meaning feeding on dead and decaying matter that’s just naturally in the soil. So, because of this, it’s also considered beneficial, many other fungi, it’s breaking down organic matter and contributing to our cyclical, decomposing of matter. And it can also live as an endophyte, meaning it can be symbiotic with plants and live externally on them, and potentially fight off insect pests that would land on the plant. But we won’t be talking as much about that today. | Image of Metarhizium fungus growing on an agar plate. It appears green and dusty with spores. Text to the side reads: genus of entomopathogenic fungi, naturally present in soils around the world, saprotrophic, performs beneficial functions of the ecosystem by colonizing rhizosphere, can live as an endophyte |
| So here’s that non-infective life cycle. Where we have a fungus living in the soil, and, you know, fungi, they have mycelium, which is kind of the main, like, vegetative part of the organism, the fungus is mainly the mycelium, and then the mycelium will produce spores, also known as conidia, with this type of fungus, and the spores are dispersed either through air or through the soil. And those spores can either end up back in the soil, and then continue this growth. The mycelium will grow from those spores, and it’ll continue its life cycle in the soil, or it can do the thing that we care more about, right? Where it does its infective life cycle. | An image appears illustrating the non infective life cycle of metarhizium: spores grow into threadlike networks of mycelium, which produces more spores, surrounding an image of a plant in soil to show where this is taking place. |
| So with that spore, it can diverge into either life cycle. So this infective life cycle would be, the spore lands on the outside of an insect, as it’s traveling through the air, it adheres and spores are hydrophobic, so are insects’ exoskeletons, so that means. They can stick together very easily. And, once the spore has stuck to a surface, it will send out a germination tube. Which, well, I’ll explain it more in depth in a second, but basically, it’ll penetrate through the insect’s exoskeleton and grow inside the insect, starting with the least essential organs first, and then moving to the most vital organs, and then eventually, once it has killed the insect, it’ll send out spores, aka conidia. On the outside of the insect’s exoskeleton. Which is when we get this fuzzy green texture on the outside of the insect. So, and this is, of course, to exploit nutrition, as I said before, but you can also imagine that it’s really successful for an organism to have this type of ability to parasitize a living organism. Because it’s gonna help with dispersal. So if you’re this sad little grasshopper that who’s been infected by Metarhizium, you’ve probably hopped a long ways since when you first got infected. So now you’re dead in a different place than where you first got infected. And you’re sending out the spores are coming out of your dead insect body, , and now the spores have spread, and it makes sense why this fungus would have spread all over the world. And it’s also very, very advantageous to be able to flip-flop between these two different life cycles as well, because, the fungus is now exploiting whatever resource is available to it at the time. | Title text reads “metarhizium’s infective life cycle” next to an image illustrating the infective life cycle, starting with spores, then germinating into the insect exoskeleton, infecting the insect body, and finally more spores appearing in a dusty green texture on the insect’s body. Molly talks through each step of the life cycle. Text to the side reads “metarhizium can flip flop between these two life cycles to exploit available resources” |
| So yeah, here’s kind of a closer look at that life cycle. We have spores being dispersed through the air, landing on an insect’s cuticle, and then it’ll send out a germination tube, which is, like, the first strand of mycelium it produces. And that germination tube forms something called the appressorium, which is this, plug-like structure here. And the appressorium will secrete all kinds of specialized enzymes that are very specifically, , geared towards breaking down this waxy, chitin-rich cuticle that the insect has, so you know, they’re not like us, soft and fleshy, they’re hard on the outside, so, very specialized adaptation for the fungus to be able to break through that, and then and it’s also using turgor pressure, which is interesting as well. So this appressorium uses enzymes combined with turgor pressure to break through. And then it’ll grow more mycelium inside the insect’s body. And I mentioned it’ll target the least vital organs first. The reason for that is because if the fungus was gonna target, like, the most important organs that the insect needs first. And the insect dies right away, now the fungus is gonna have to compete for these nutrients with all kinds of other bacteria and fungi that are now on this decaying, dead insect. So all of this is, like, super highly, specialized. | Another slide showing the infective life cycle on a drawing of an insect larva. A spore is adhered to the larva, with mycelial threads entering the body, and growing to produce more spores on the outside of the insect. |
| And then, here’s what these dead insects would look like with spores then being produced on the outside after they’ve been filled with mycelium from this fungus. So, we get this fuzzy green texture on the outside, kind of like what mold looks like, if we were to look at that under a microscope, or swab one of those and put it on a microscope slide, we would see a bunch of little tic-tac-shaped spores that I’m gonna show you in just a second. And so, again, this is super highly specialized. Metarhizium, is a genus, so there’s many different species of Metarhizium. And depending on the species, this fungus can be either a specialist, where it is known to only infect, like, a certain group of insects, or even just one species of insect, or they can be known as, like, generalist. Where they’ll infect many different kinds of insects, but yeah, so very diverse. And not only that, but Metarhizium is not the only fungus that does this, and I’ll talk about more about that in a minute but just know that there are many different kinds of entomopathogenic fungi in all different clades of fungi. This is not just one group of fungi taxonomically, that are able to do this. There are many different kinds that do this. | Dead insects infected with metarhizium, including a grasshopper, grub, and stinkbug, all of which are covered in a dusty green texture of spores. Text appears reading “ metarhizium is a genus comprised of 70 species, known up to infect 200 species of insects”. |
| And surprisingly, we’ve actually known about this, for a long time. So, originally, Metarhizium was discovered by Eli Metchnikov, who is kind of known, for discovering a lot of early pathogens, and he originally discovered this fungus growing from a wheat grain beetle, which is one of these little guys. Within a decade, he was able to get this fungus being used as a biological control for wheat grain, these wheat grain beetles, across Ukraine, and it was already pretty effective, so this is something that was being used as a biological control very, very soon after its discovery. And now, Metarhizium is used commercially as a biological control for many different arthropod and insect pests. So, currently there are over 40 different, products available on the market for different, purposes, they use Metarhizium as its main active ingredient, so it’ll be Metarhizium spores in this bag, Plus maybe, like, a carrier agent, like a carrier powder or a carrier liquid. | Title text reads “discovery and early use”. An image of Elie Metchnikoff sitting next to a microscope, with another image of a grain beetle. Molly reads text off the slide explaining the early use of the fungus. |
| MET52 is one of the main products that, s most well-known, I would say. And, this would usually be for plant crop pests, where, the spores are getting dusted onto the foliage of some plant crop, or tilled into the soil to naturally boost the populations of these fungi that might already be there. But, of course, with any biological control, the efficacy of the biological control being effective against our pest organism, is going to always be dependent on the different conditions that are favored by that organism that we’re using in this situation, are conditions are going to be favorable, based on, is the spore able to germinate? | Title text reads “current use of metarhizium in integrated pest management” next to an image of a pesticide product bag labeled “Met 52” next to an image of a metarhizium culture plate. Text reads “47 commercially available products in 2007, usually for plant crop pests, applied onto soil or directly onto plant crops”. A bubble appears saying “efficiency of application is dependant on conditions favored by the fungus” as Molly explains. |
| So, with that being said. What in the world would be stopping us from just dumping a whole bunch of spores into a beehive and saying “Kill the mites! Let’s… let’s have it do its thing!” What environmental conditions, specifically, would be different? | An image of WSU researchers working on commercial hives in a large field as bees fly around them. Text reads “what is stopping us from managing varroa mites with metarhizium? What conditions differ in the hive?” |
| It would be temperature. So, in the beehive. The bees are constantly working to regulate that temperature and keep it around, these numbers are a little off. More 32 to 36 degrees C. And, specifically the brood nest, which is where our mites are going to be reproducing and developing. So, that would be something that we specifically would want to target would be the brood nest, and unfortunately, these spores are not as likely to germinate at these high heat temperatures as they would at temperatures more close to what you would normally find in the soil around the world. And sure, maybe there’s some areas where the soil gets really warm, but never usually this warm, right? So, while we know that Metarhizium does have effect on varroa mite populations, it does successfully kill them, in the beehive, it has never been, at a rate comparable to that of miticides that we would use. So In order to be able to apply this and be like, this is as reliable of a treatment as miticides that a commercial beekeeper would use, we need to find a way for the fungus to fare well in these high-heat environments. | An image from a heat camera shows the warmth of the bee cluster reaching up to 35-40 degrees celsius with an illustration of bees clustering together to thermoregulate. Text reads “ the colony is constantly working to regulate temperatures” |
| So, one way to do that would be, developing the fungi into strains that are thermally tolerant. And in 2021, this paper came from my lab, where two of our researchers were able to develop. | Title “ work with metarhizium at WSU” over a screenshot from a journal database showing the WSU publication titled “Directed evolution of metarhizium fungus improves its biocontrol efficacy against varroa mites in honey bee colonies”. |
| A phenotypic strain of Metarhizium that, showed tolerance to high heat environments, and was effective against varroa mites. And here’s a little bit of how they did that. So, It starts with a spore. In this case, they called it a mitospore, but Mitospore, conidia, same thing, just an asexually produced spore, because this fungus grows asexually. Starting with a spore, they would grow this on media, and then by media, it’s usually gonna be an agar plate. And they would expose the fungus to either oxidative stress using hydrogen peroxide or nutritional stress, meaning the agar had very, very low nutrient value. … And the purpose for exposing the fungus to stress is to increase the rate of potential mutation that is gonna occur genetically, and we need that because I mentioned this is an asexually reproducing fungus. Meaning, we’re not getting as high rate of genetic recombination with each generation of culturing. So, they would expose the fungus to stress to hopefully get more genetic variation in that growth. And then they would mix up those spores, and then incubate them at a higher temperature, and then repeat this over and over. | Graphic showing the selection process, starting with spores, moving with arrows through nutritional or oxidative stress, to a new agar plate, moving to a pipette where spores are mixed, and then an icon showing temperature increase. An arrow connects this back to the first step of growing spores to make a circular chart. |
| And then in the field, they would apply, . This fungus onto the beehive with just an agar plate with some spores. And then collect mites that fell to the bottom of the hive, dead and put those on agar plates. And you can see in this picture here these, 6 dots growing on these plates here, our fungus growing out of these dead mites that they’ve plated. And then they would culture from. That fungus and then repeat the process again and again. | Another circular chart, this time with images of selecting mites for culturing. An image of a metarhizium culture plate points to a bee hive and shows where the agar is placed on the top of the frames inside the hive. An arrow leads this to an image of mites, some of which are growing green sporulating growth on culture plates. An arrow connects this to a clean culture plate to show that it gets inoculated, and a final arrow connects this back to the original culture plate. Molly talks through each step of the circle. |
| And here’s, something that shows their success, so, what we’re looking at here are those spores that I mentioned with germ tubes emerging from them. And you’ll notice in the top row here, which is spores not selected for the high heat environment, they were only able to produce some short germination tubes, or no germ tubes at all, versus this strain that they selected to be thermally tolerant, was able to grow these really long, prolific germ tubes. So, both of these were incubated at 35 degrees to allow for these germ tubes to germinate, and this is a very clear example that this strain is much more successful at that high heat environment, because they’re able to produce these very prominent germination tubes. | Images of spores under the microscope. The top row of spores, not heat tolerant, are germinating with very short or no germ tubes emerging from them. The bottom row of photos, showing the heat tolerant strain, is producing much longer germ tubes that are distinctly more vigorous. |
| So when I joined the lab and started working on this project, we were producing Metarhizium, we’re trying to produce it in mass amounts by growing it on this brown rice. And so, of course, this is all done in sterile conditions in our hood here, because if we were to open this brown rice or open an agar plate out into just an open room, there’d be other fungi in the environment that would grow on there, so we do this in this sterile space where we’re able to scoop the contents of that agar plate into a bag of brown rice here and let the fungus, grow throughout the rice and of course, we have to have our super special, organic brown rice that doesn’t have any mycoinsecticides in it, so that means somebody has to go to Costco a lot, which is usually me. | Image showing brown rice prepared in plastic bags in a sterile workspace, along with an image of a hand holding a culture plate full of spores. Title text reads “Early cultivation steps at WSU”. Images appear of molly pushing a shopping cart full of brown rice bags. |
| And once that bag of rice is fully grown with Metarhizium and is visibly heavy with spores, meaning it’s all green and dusty, like how a moldy apple might look, we will open it up in that sterile space. And weigh out 400 grams of that colonized rice that now is, full of spores, and we put it in these brown paper bags. And you can see we’ve added a spacer to the top of the hive here to give an extra, like, inch and a half of space for this bag of rice to sit. And then we’d tear a little hole in it. Actually, I have a little video of it here. So, just opening the top of the hive and placing this bag in here, and the idea is that the bees, you know, they don’t want this random paper bag in their hive, so they’re going to be tearing at it and interacting with the rice, and the rice will fall out at some point, and they’ll be getting spores onto themselves as they’re moving it, and then they’ll be cleaning each other and getting spores onto each other, and the goal is essentially just to get spores all over the bees where the mites would be. | Image of paper bag full of metarhizium sitting inside a bee hive with bees crawling on it. Molly plays a video of her and her colleague opening the hive lids to place the paper bag of metarhizium. |
| And, in order to monitor how effective these treatments are, this is what we do. We use these cards that we get that fit in the bottom of the hive. They slide right through the entrance, and we coat them with Vaseline. And this just allows us to pull the card out every week, or every two days, however often we decide to for that experiment, and, we’ll count the number of mites on the bottom, and then this is also where we can collect mites to then culture like that last paper I just showed did. So there’s a mite on the sticky card. | Title text reads “monitoring mite population” over an image of a paper sticky card removed from the hive, with varroa mites trapped on the card. |
| And while we were seeing some effect of Metarhizium on these field trials, it was not quite enough to really continue going with that those methods we had… we had decided on, and so we did what you do very often in research, where something doesn’t work on the scale that you’re goal is for it to work on, and so you just gotta scale it back and look at it a little closer in the lab again first, and then later try again in the field. So, last fall, we did this in vitro assay. Where we tested the Metarhizium in lab conditions. And we did this on testing it on Varroa mites but of course, if we were to collect a whole bunch of mites off of bees and, have them in, like, a dish or something in the lab, they would die right away, right? Because they’re going to be starving without their honeybee hosts. So, in order to pull this off, we had to manually pull out a whole bunch of honeybee pupae. And place them in these centrifuge tubes to replicate, sort of, what a brood cell condition would be, and then we put mites on those pupae. | Title text reads “metarhizium on varroa mites – in vitro experiments” next to a gloved hand holding a centrifuge tube with a bee pupae and mite inside, bullet points read “ honey bee pupae are removed from comb for varroa mites to be laced on. Replicating the environment and conditions found in the brood” |
| And actually, Getting ahead of myself, because I have a video that. Shows exactly what I just explained. So, in this video here, my coworkers and I are pulling out mites from brew frames and collecting them into this jar, and then at the same time, we’re also removing pupae from, the brood cells as well for these centrifuge tubes. So, it was very tedious, we had to get everybody on board together in order to collect enough in a day, and we learned that paintbrushes, specifically camel-haired paintbrushes, are the best way for picking up mites. If you ever need to manually pick up varroa mites, using a little paintbrush to twirl under their little feet works really well. | Title text reads “manually collecting mites and honey bee pupae from brood colonies” while a video plays showing Molly and her team manually collecting mites and pupae from frames of comb. |
| So once we collected all the mites, and we collected all the pupae, some of the mites were treated with Metarhizium spore solution, which I’m making here, just by swirling some of that Metarhizium-colonized rice in some solution, and then filtering it out. And then these mites we collected were individually dipped in that spore solution and then placed on the pupae. And then, for our control group, we used just the solution on its own, which is Tween 80, between 80, it’s basically just a surfactant, an emulsifier, so it helps the spores not to be all clumpy in the water. If we were to just have the spores in water, they would clump up. So, we made the Spore solution. I’m filtering these spores in a solution Tween80, and then the control group was Tween 80 on its own. | Video plays showing the next steps where mites are set on filter paper to have spore solutions poured over them. Text to the side reads “mites in the treatment group were submerged in spores solution (metarhizium spores in tween solution). Mites in the control group were submerged in control solution (Tween 80) |
| And we monitored mortality every single day, so every day we look there and see if any of the mites are dead, and any dead mites, we would collect using our paintbrushes, and then plate them on the agar plates. And surface sterilize them first, right? Because there’s gonna be contaminants on their bodies that would grow on that agar plate if we didn’t do that. | Images showing gloved hands collecting the mites with handheld tools and placing them on culture plates. Another image shows fuzzy fungal growth coming from the plated mites. |
| And after 5 to 10 days, we see this noticeable growth coming out of the mites, so right in the middle here was where a mite was placed, and this green fuzzy growth coming out is, characteristic of Metarhizium. | Image of Molly in labcoat holding culture plates to examine them. Next to an up close image of a culture plate with fungal growth coming from a mite. Text below reads “examining growth after 5-10 days” |
| And we actually got pretty successful results from that. So, , this red line here is representing our rate of mites dying that were treated in the Metarhizium group, and then, down here, our black line is the control group, and you can see that by day 5, we had over 50% higher mortality in the treatment group versus the control group. So that’s pretty significant. And 5 to 10 days, correlates with the amount of time it would take Metarhizium to kill an arthropod, so it makes sense. | Molly talks through the graph showing the results from the experiment. The graph shows the mortality rates of the treatment and control groups. The treatment group starts having rapidly higher mortality starting day 2, and by day 7, has over 50% higher mortality than the control group. |
| Now, the question on everyone’s minds, I’m sure, is. How do you know this fungus isn’t just gonna kill all the honeybees if you’re dumping a bunch of spores in the beehive. And there are spores that are geared to kill insects and arthropods, aren’t they just gonna kill the bees? And that’s a very valid concern to have. , and luckily, we have very good reason to not feel concerned about this for a few different reasons. So I’ll explain. So, first of all, . You know, we’re not the only lab who’s done stuff with Metarhizium for varroa mites. There are other institutions out there researching it, and luckily, there have already been studies done that have shown. That Metarhizium had very, very little effect on, bees in general. So basically, it was very, very hard for Metarhizium to infect adult bees. And then larvae and pupae had around a 5% mortality rate when researchers were directly inoculating the fungus into the brood cells. So, that might not necessarily represent the numbers on if it were just being applied. In the hive in general, but when they specifically put the spore solution into a brood cell that had a larva in it that they had about a 5% mortality rate. And that could potentially be acceptable, because if we’re wanting to target the brood nest and get, whatever treatment we’re using thoroughly applied throughout the brood cells where these mites are going to be reproducing and developing, 5% mortality of larvae could be acceptable If we’re also getting, like, 98% mortality of mites, right? So if you’re a beekeeper, and you really just want those mites gone, and It wipes out all of them that are exposed with all the open brood then, and it only wipes out a little bit of your larva. I would find that acceptable, personally. And the reason that it’s speculated, it’s so hard for these fungi to affect adult bees, is, first of all, bees are very, very fuzzy. So, in this picture here, , this bee is covered in pollen spores, and you’ll notice all of the pollen is being held away from the bee’s exoskeleton because of this hair. And that’s what the hair is meant for, right? It’s for collecting the pollen. So, it’s very likely that spores landing on the bees. , could produce that germ tube and not be able to reach the bee’s cuticle, and then the other kind of big defining factor about bees that also is the reason we’re not as worried about it is bees are very hygienic. They’re always cleaning each other and cleaning themselves, and you know, they have their specialized. Morphological features for combing their antenna, and they’re very, very hygienic. So, it’s also likely that if spores are getting on the bees, they’re immediately cleaning it off of each other, and then moving on to the next bee, and then getting cleaned off of that bee. So the mites, on the other hand, if you picture them with their little legs, they’re not really they’re not going up and combing stuff off the top of their bodies, so… It makes sense that spores are probably getting disrupted before they’re able to germinate on bees. And what’s also really great is that Metarizium imposes, minimal health risks to human and mammals, meaning. It’s not good to read spores, right? With with any kind of fungus, you don’t want to be inhaling spores, that’s going to irritate your lungs. So, Metarhizium is known to be a very, very low-risk pathogen. In fact, it’s considered, Bsl1, biosafety level 1. Meaning lowest, lowest level possible, and I actually learned recently, our food science labs on campus are also BSL1, meaning, we would have the same standards in our lab, working with this pathogen as they would working with food. So, very, very low level, , risk, and, one last thing about the risk towards bees. As we continue developing this and doing this research, we’re always going to be monitoring the effects that the fungus has on the bees, because when you’re working with any pathogen, you want to make sure that it’s affecting things in the way you want it to, right? So, even though we’re very, very confident that this is not having major negative effects on honeybees we’re still gonna be,keeping track of that along the way, and measuring, like, bee mortality and things like that, but because we want to make sure we’re… we’re… protecting our bees. | Text reads “how will this fungus affect the bees” next to an image of a honey bee forager. Bullet points appear reading “so far, studies have shown that metarhizium has minimal effects on adult honey bees. Shown to infect a small ratio of bee larvae- trade off for mite management. Bee hair and hygienic behavior” A green box appears after Molly speaks saying “Metarhizium poses minimal health risks to humans/mammals!” |
| So, one of the next steps is going to be confirming the best mode of application for this. I mentioned the rice thing did not work quite as well as we had hoped, and there’s many different modes of application, right? So when you think about different ways to apply oxalic acid, you can apply it in a solution, dribble, you can apply it in a more passive way, like where, like soaked towels, which is kind of adjacent to the rice thing. It’s very passive, where, like, the bees are being required to interact with it in order to get the treatment on them, versus something more direct, like the dribble or vaporization, where we’re just putting something in there, and it’s automatically getting all over the bees. We don’t have to wait for the bees to perform any action for the treatment to get on them, so similarly, we can think about direct and passive modes of application for Metarhizium. And the goal, again, is for this to work on a commercial level. So with that in mind, it has to be something that’s gonna go fast. So, you know, we can’t individually. Open up a hive and dip every mite in Metarhizium solution. We have to be able to go up to each colony and maybe stick something in the entrance to aerosol spray the spores everywhere in the hive in under 30 seconds, something like that, because if it’s gonna take too long, commercial people aren’t gonna use it,which is understandable. | Title text reads “ next steps – modes of application” over images showing different application methods of miticides including shop towels being placed in between boxes, a plastic syringe dribbling a liquid between frames, and a beekeeper placing a vaporizer in the entrance of a hive. Text appears reading “what type of application would work best for spore dispersal in the hive”. Bullet points to the side read “determine most efficient mode of application, direct vs. passive applications, application needs to be efficient at killing mites, but also needs to be easy and quick enough to be done in a commercial setting.” |
| And other next steps, is looking at other entomopathogenic fungi, and this is no longer really a next step, this is a current step, because this is now what I’m currently doing, but you know, I mentioned earlier that there are many other different kinds of entomopathogenic fungi other than Metarhizium. I talked about Metarhizium this whole time, but it’s just kind of one of the main ones already used. There are so many other different kinds of fungi that also perform very, very similar. Modes of action to, in fact and kill insects. So, by looking at more than just Metarhizium, by looking at other fungal taxons, I think we’re more likely to find strains that show , high effects in high heat environments if we look at more groups versus just one, right? We’re gonna have a wider genetic pool. | Title text reads “next steps – other entomopathogenic fungi” over a stock image of an iceberg. The top part of the iceberg has a bubble with the word “metarhizium”. Below the waters surface, the iceberg has bubbles listing names of other entomopathogenic fungi. |
| So, that brings me to the research I’m doing, personally. Is working with these three different species of entomopathogenic fungi and developing them for thermal tolerance. So, this is to measure their effect on Varroa mites, as well as just see how well these three different fungi respond to my selection techniques, and how differently will they change over time as I’m culturing them. | Title text reads “Fungi I’m selecting for thermal tolerance” over culture plate images of Metarhizium brunneum, appearing green with spores, Hirsutella thompsonii, appearing wrinkly and white in growth, and beauveria bassiana, appearing fluffy and white. |
| This is what I’m in the middle of doing right now, the first step whenever you’re selecting a strain or, performing any kind of selection with any kind of organism. You kind of first have to do an initial screening. So, for me, that was incubating these fungi at the four different temperature points that I decided on, ranging between 27 degrees Celsius and 35 degrees Celsius, and so I had 3 reps of each species. In each incubator. And doing this initial screening kind of just gives me an initial idea of how vigorous these fungi are going to be at these different temperatures. And it also gives me something to select from, so if I, you know, for example, see a plate doing really, really well at my second to highest temperature. I’m gonna select from that to continue the next generation. So you can see here in this picture on the right, I have 4 sets of plates, 3 in each set. And, this group of plates on the top basically have no growth. So that dot in the middle is where I transferred some mycelium. And they didn’t grow at all. So these are the plates that are from 35 degrees Celsius when I first started, and you can see they’re not suited for that environment. They’re not gonna grow at 35 degrees Celsius, versus these ones on the bottom here that completely filled out their plate. Those ones were grown closer to room temperature. So right away, this kind of gives me an initial idea of how easily these fungi can grow at different high temperatures, and that’ll be something I can compare my strain that I end up with to later. | Title text reads “ first step: initial screening and incubation” over images of lunch trays sitting in a shelved incubator with culture plates laid out on them. One image shows plates that grew on the entire plate, while others have very minimal or no growth. |
| So, after I have this initial screening done, I select a single spore from the cultures that I decide to carry to the next generation. And I do that by looking under the microscope here, and these spores here that just have their regular tic-tac shape. You’ll notice they don’t have any germ tubes. So these are spores that are ungerminated that I would not want to select from, and I guess, I don’t know if I clearly really said it yet, but. the reason we care so much about the spores germinating and producing these germ tubes is because that is what starts this mode of infection, like, this infected life cycle that they’re carrying out. So if you go back to earlier with the life cycle. It always starts with a spore germinating and putting out that germ tube. So, if we were to just grow a whole bunch of Metarhizium mycelium and then put it on an insect. It wouldn’t do anything to it. It’s all about the spore germinating, so that’s, like, kind of our unit that we care about when we’re developing this to be thermally tolerant, so these ones, un-germinated, I wouldn’t want them. I would want one that’s germinated, so this picture on the right shows a bunch of spores that have sent out these long germ tubes, and so taking a sterilized needle, I’ll get in there really closely and just touch that strand of mycelium, and then touch the middle of the next plate, and that that tiny fragment of mycelium that gets transferred over is enough to then continue growing onto that plate, and so that starts my second generation then. So, again, by doing this, you know, I’m selecting from a spore that has germinated at whatever temperature I’m growing it at. So I know it’s able to carry out its lifecycle successfully, but then the other benefit is that when I start working from just one spore, I now am only working with one genome. So, if I were to just scoop up a bunch of these spores that germinated and have them growing on a plate, I’m working with however many different genomes. Like, it could be hundreds or thousands. By working with one spore from this point on, or at least selecting one sport for the next generation. I can know that I’m just working with one genome, and that means I can actually select a strain versus something that is just phenotypically exhibiting some trait of thermal tolerance. I wanna I want to have a defined spore genome that I’m working with, and I can later have some kind of genetic marker that is that shows that that strain is very distinguishable from, what I started with. | Title text reads “selecting single spores”. Molly circles around the images, highlighting an image of spores that are ungerminated, and remain tic-tac shaped with no germ tube. The images of germinated spores show tic tac shaped spores under the microscope with very prolific germ tubes present. Text reads “selecting the next generation from a singular spore means working with a single genome = better observation of genotypic changes”. |
| So once those spores are on new plates. Each their own individual plate. , they will start growing more mycelium. So, and that’s what that would look like under the microscope, the germ tube will start sending out more and more strands, and it’ll form this network of these, branching mycelium structures. | Title text reads “transferring viable growth”. An image shows molly holding a culture plate with spores, next to an image of mycelium under the microscope forming a thick, mat-like web. |
| Here’s kind of a closer look at that. So, hyphae are kind of a single strand of mycelium. I’ve been saying mycelium grows from the germ tube. It’s really hyphae that then meshes together to form this mycelial net, but yeah, so selecting, , the first strand of hyphae from a spore, letting it grow out at the higher temperature, then so I’m slowly acclimating. These fungi to higher and higher temperatures as I select through these generations. | Text reads “hyphal growth. Selected spores are grown onto new culture plates. Spores germinate into hyphae which grows together to form mycelium.” An image of spores is connected with an arrow to more images of mycelial threads under the microscope. Text underneath reads “the generation started from this hyphae is incubated at 32.5 or 35C and then the process is repeated.” |
| And as I go through this, it’s one thing that’s really important is making sure that these fungi aren’t losing their traits that allow them to be virulent towards insects. It’s very possible that somebody could, over time, unintentionally select a fungus that. Now is just really crappy, and has lost its ability to carry out its infective life cycle if I’m only exposing it to this agar plate nutrient situation in the lab, right? So, every few generations, I make sure that the fungus is still maintaining its virulence, by applying it to wax moth larvae. And then, observing their mortality as well. And the reason I do this with wax moth larva, it’s kind of funny, because when I talk about this, a lot of times beekeepers are like, why are you rearing wax moths? We don’t want them! But they’re actually really, really useful in lab settings like this when you’re working with an insect pathogen because they are very, very easy to rear in the lab. And to rear a lot of them quickly. And they’re very good hosts for passaging pathogens on, because they melanize very quickly. So, these pictures show ones that are already completely dead, and they’ve turned completely black, but if I were just to show you one that is in the process of being infected and still alive, it might just have, like, one black spot on it, I need to get more photos of that, but essentially, because it melanizes very rapidly, I can visually observe the infection spreading throughout the wax moth larvae. So, to do this, it just kind of is a little check that even though I’ve had this fungus on agar for so long, it is still virulent towards insects, and it still is able to carry out its infectious life cycle. | Title text “Ensuring virulence” next to images of living and dead waxmoth larvae. The dead larvae are completely melanized and appear black. The living, healthy larvae is a healthy white color. Molly reads the text off the slide. |
| So, this is what that cycle looks like as a whole. I start with this initial screening. Select mycelium from that and then grow it out, select individual spores and their germ tubes. And then continue this over time while ensuring virulence along the way. So currently, I’m in my third generation of selection, with my three different species of fungi that I’m working with, and of course, they’re all getting grown separately, and, getting exposed to the same conditions over time, and I’m measuring how they each are able to react and change, based on these selection methods. | Graphical summarizing this whole process. Initial screening on culture plates goes into the cycle of selection, starting with mycelium starting the generation, then individual spores being selected, and ensuring virulence on waxmoths, and then repeating. |
| So, looking ahead, here’s kind of the timeline of what the goal is for this project. Ultimately, the goal would be having this be a registered product that commercial beekeepers are able to purchase and apply, and not just commercial beekeepers, right? Any beekeeper could purchase this, is the goal, and use it as a biological control that is effective and everything. So currently, I’ve spent a lot of time over the last year figuring out what protocols are best and what selection methods are best for working with these fungi based on previous work, and then I acquired my starter cultures from these different USDA culture collections, and they came in these little freeze-dried packages that looked like this, and I had to hydrate them and saw them, and then I did my initial screening, and now I’m here in the screen selection period. So, like I said, I’m in my third generation. And I’m going to be going to be continuing this selection method all winter, with the goal of next spring 2026, doing a field trial with my three different fungal strains. Or maybe just with the one or two that show the best results in lab conditions, or something like that. But the goal for the next 6 months for me is to gear this into field trial setting, and then with that, continuing to confirm the application methods, whether that’s some kind of aerosol spray or some direct application, or some more passive application that we test, and then I want to be able to find a way to distinguish these strains I develop from their original cultures that I started with back here. So there should be some kind of genetic marker related to thermal stress or something, or germination rate, something that should be different than what I started with and I can genetically identify it, and people can have primers, then, that would help them identify the strain and. And such, and we can distribute it, but first, before any of that, any of the distribution, it has to get approval from the EPA. So, along with any other pesticide product, we need that approval. And then finally, it’ll be registered. So who knows how many years that will be until it’s registered, but the goal for this is that it will be the first biological control for varroa mites, and that it’ll have very effective control, while also not affecting bees. And yeah, hopefully offering a reasonable alternative to other miticides that mites are already resistant to. | Title reads “Looking ahead” with a picture of Molly looking at agar plates. Molly reads bullet points off slide. |
| So to kind of wrap this up and conclude, we know honeybees are facing a lot of problems right now, mainly the varroa mite. And this is something everyone should care about, because everyone needs to eat. And Metarhizium, it’s already used commercially for all kinds of insect agricultural pests. It could be the first biological control for rural mites, if we can develop some thermally tolerant strains and figure out how they can best be applied in the field. So, at WSU here, I’m gonna be here as a grad student for the next few years, at least, working on this project, and really excited to see where this takes me. | Title text reads “Conclude” over an image of bees on a frame of comb. Bullet points read “Honey bees are declining, and varroa destructor is the main stressor. This decline could have a huge negative impact on our food systems. Metarhiziu mshows potential to become the first biocontrol for varroa mites, but a thermally tolerant strain is needed first. At WSU, we will be continuing this development, investigate the virulency and thermal tolerance of other fungi, and examine the most efficient application method. |
| So, I hope that this was interesting for everyone who’s watching this, and I hope that, I’ve shown you at least one way fungi can be used to help honeybees, and there’s, of course, others we can talk about, but. This is the main one that I’m really excited about, and yeah, fungi are so cool, so this is just one other reason to really appreciate them. | The same images that we started with of an amanita muscaria, shiitake mushrooms, people gathered for foraging, and spores under the microscope, connecting back to the original point. |
| So, super special thanks to everyone at WSU who’s, helped me with this. This is my project, the thermal tolerance part, but, this has been a collaborative project in general to do all this work with this fungus. And, also special thanks to the Washington State Beekeepers Association for choosing my research to fund. So, they funded me they chose me for as one of the people, Taydin was the other person who got it, last year, and then this year, I was one of the people to receive it again, along with Bri. So, thank you to WASBA for awarding us for supporting our research. | Acknowledgements slide. A scene of honey bee hives at an orchard appears with images of the WSU honey bee lab logo, and an image of graduate students Molly and Taydin standing with Alan Woods the president of the Washington State Beekeepers Association. |
| And with that, I’m happy to take any questions, or thoughts or ideas or suggestions that anyone has. Bri: Great job, Molly, we did already get a comment in the Q&A saying, brilliant, I cannot wait to start my Master of Science on a topic like this benefiting honeybees. Thank you. Molly: Nice, right on! Bri: All right, if anyone has any questions, go ahead and type them in the Q&A. Of course, we’ll wait here for a bit to, see if anyone has questions and give you time to type them. We got another comment here: Thank you for a great presentation, Molly. Molly: Oh, you’re very welcome. Bri: Okay, we have another comment here. Not a question, but thank you for the fantastic presentation. Again, all the comments, Molly, and it was very great. Molly: Well, thank you, everyone. While we’re waiting for any questions, I thought I’d throw these electron micrographs up here. I’m currently in an electron microscopy imaging class here at WSU, which is just amazing that they offer a class like this. That’s not normal at all for a university to offer, as far as I know, but basically, they just let you image whatever stuff you have for your research, so here’s some images here of these Metarhizium spores in the chains that they form, naturally. Bri: So Cool. Okay, someone else said really cool research. we got a question here, incredible. Will you be needing a field study location, perhaps a local farm? Molly: Woo! Yes, so something that we get asked a lot about these is. Can I be part of this? Can you test this on my bees? and in the past, we’ve tried to do some good citizen science work with this and something I did not really mention at all in this research in this presentation is that in order to do this research, we are currently having to commute outside of the state of Washington. And the reason for that is because in the state of Washington, you’re required to have a special use permit for any type of unapproved, pesticide only for honeybees, for beekeeping, An indoor potato fumigation, which is really, really wild if you think about it, because that means in the state of Washington, if you have some unapproved experimental pesticide that could potentially be really dangerous, and you’re applying it to, like, a cornfield or some big field, that’s fine, but for some reason, we need this special use permit just for apiculture, and Indoor potato fumigation, if you have an unapproved pesticide. So, we commute to Moscow, to do these field trials. And we are in the process of getting this special use permit so we can start doing this in the state of Washington. And once that happens, we’re hoping to open this up to be, like, a Washington State citizen science project and when that happens, you’ll probably be hearing about it, because we’re going to be looking for people to be willing to let us test this on their bees and observe the effects. So, stay tuned for that. Currently not doing that, but definitely planning to do that in the future, because doing citizen science projects like that is really helpful and insightful. But I’m glad that people are interested and would be willing. Bri: Will you continue to study the effects this might have on people, also? Molly: That’s a good question, yeah, so… I mean, we’re an entomology lab, so I don’t think we’re really gonna be doing any experiment where we’re trying to grow it on any fleshy organism, but I do get a lot of questions about that pretty often, especially because of this dang show that I think is proliferated the idea, The Last of Us, that this fungus could develop thermal tolerance and parasitize humans, and kind of the main reason. There’s no, fear of that happening, realistically, is that, like I mentioned, these fungi are so, so specialized for penetrating the waxy, lipid-rich chitin-rich cuticle that insects have, and this is something that they’ve evolved for so long to be able to have that capability. I do not see a possibility of the fungus being able to penetrate human flesh and parasitize humans, at least not for millions and millions of years, for that evolution to happen again. Yeah, but… but yeah, definitely something to keep in mind. Probably more what we will be considering is what would be proper ways of application that would reduce the amount of PPE someone needs, so If it is, for example, what I mentioned with, like, aerosol spraying spores, we would want to do that in a way where the spores aren’t getting out and in spraying in someone’s face, right, or maybe they’re required to wear a respirator, how you would with oxalic acid vaporization, something like that. So… We’re probably not gonna study how it affects humans, but yeah, not much worry about it infecting humans. Bri: How long do you perceive it may take to come to commercial use? Molly: Oof, that’s a big question, and I don’t know if I have enough experience in this world to really say that, but I would say it could be a while, … at the minimum, it’s gonna be at least, some years. , I don’t know if I, yeah, have much more to really guess about that, but it’ll at least be, like, several years, I would say, until this is a registered product, just because that’s how long it always ends up taking to registered products. Bri: All right, we got another question. Has the temperature differentiation in the modification of the fungi at all shown to have different efficacy with the structure or anatomical thickness of the chitin on mites or other. Meaning, does the temperature affect both host and vector? Molly: Ooh, interesting. Well. Let’s see, maybe I don’t fully understand the question, but… If we’re… we’re only gonna be testing it on mites. , in that high-heat environment, because the mites would not survive at a lower temperature. So, over time, we should see, you know, higher and higher mortality rates on mites, as we select a thermally tolerant strain, because the mites are going to be at that heat level, but yeah, I mean, if we were to have the mites at a lower temperature, I imagine they would die pretty quick, if I’m interpreting that question right, but feel free to ask it again if I’m misunderstanding. Bri: How long are the spores effective or viable once applied with a propagate themselves, or would you have to reapply the spores at a regular interval? Molly: That’s a good question. So, something interesting in that 2021 paper that I showed the title of, I don’t know if it’s actually mentioned in the paper directly, but I know that those researchers who did that, they were able to swab the hive. In the spring, when they had treated it with Metarhizium in the fall, and they were able to swab some spores, like, I think it was right on the top where those frames were that the agar plate was, like, sitting on, so it’s like, there was some spores left there from where the agar plate was. And, they were able to say they were able to show that the spores were still viable after that overwintering had occurred, however, those were just the spores that were left over from that agar plate. It wasn’t like the fungus was, like, proliferating itself in the hive. And, you know, it would be really cool, and like, we’ve kind of talked about, like, oh, could this fungus potentially then continue growing in the hive? And, like, you know, it’s a saprotroph so could it maybe grow on the wood, or grow on some other substrate in the hive. And, personally, that could be a possibility, but I kind of foresee this as something that people will need to treat. Again, with, just because, at least currently, we’re selecting for spore germination, right? And, in order for a spore to, germinate, that’s one thing, but for it to be fully myceliating and producing more spores, that’s a whole other thing. So, if we do have a thermally tolerant strain that’s able to perform that whole action, maybe it would be, like, producing more spores on, like, the outside of the mites that it killed, but there wouldn’t be any, like, substrate or surface that would be growing more spores. Because of that, unless we figure out other things, I could be wrong. I kind of foresee this as something that you will need to treat multiple times with, and maybe they’re maybe you would see some slight residual effect over time with some spores still kind of being in the hive, but, I’m thinking you would need to apply more spores, but I’m very interested in trying out, maybe making, like, a frame that has some kind of substrate instead of, like, letting the bees use it as a frame, just, like putting a frame of some kind of substrate in there, and maybe having a fungus growing on it, and seeing how long is it able to stay active and alive in there. That would be interesting. So, gonna continue looking at that. Bri: What are your next short-term steps? Molly: My next short-term steps are going to be continuing with this strain selection that I’ve been working on, and then as well as getting more images of these spores, I was really hoping to have some spore images to show you guys tonight that would show where I’m at with my thermally tolerant strains and show those germ tubes, but, it does take a lot of time to do this imaging, so short term, that’s my next step. Bri: Okay, we have a couple questions on if this treatment would affect the honey or taste of the honey. Molly: Ooh, that’s a good question. That would be that would have to be something we’re gonna continue having to look for, but, it could be that this treatment would maybe have some limitations with when you could apply it, like how there’s some mite treatments you don’t apply when you have the honey super on, or something like that. , that’s what I would imagine, worst case scenario, if it does affect the honey. But, best case scenario, I think there’s actually a good chance that it might not affect it very much, unless somehow it was, like, a mass amount of spores ending up in a cell where honey is, because if you think about it, there’s already spores all over the place. Just like how I was saying, if I were to open an agar plate in a random room, there’s spores in the air that are gonna land on it, so, I’m imagining there probably are a lot of spores, other than pollen [grains] like, there probably are a lot of fungal spores in honey already, but yeah, definitely gonna be something to keep in mind as we develop this this into a treatment application, but yeah, I imagine unless somehow the application method is shooting, like, a lot of spores into the honey, it would probably have a very minimal effect is what I would say. Bri: Okay, and then it looks like, maybe these are the last two questions. What other pests can this fungi work on? Have other insects had Metarhizium applied to them, and what was the outcome? Molly: Ooh, yes. So… , real-world example of this that’s happening at WSU at a different location is in Wenatchee at our Extension Center. They’re developing these fungi to be virulent towards coddling moth, because, you know, in Wenatchee, they do all the research with tree fruit, you know, that’s their thing, is the tree fruit Research extension center. So, they that’s actually where my Hirstuella came from. So I mentioned that I got these fungi from culture collections. That’s the case for two of them, the one of the species I work with, I actually received as an isolate, from the Wenatchee extension, that they isolated from a coddling moth, meaning they actually just found a coddling moth that was dead with fungus growing out of it, and they were able to identify the fungus and continue growing it, and they now work with that fungus among. The other as well as the other two that I work with, so, coddling moth is a relevant one that comes to mind fresh for me, but, I mean, if you look it up, you’ll see that it’s been used for a lot of insects in agriculture, like, a lot, a lot. Thrips, aphids , yeah, citrus… I’m blanking on the name, but that one citrus bug that’s a huge pest for citrus crops, but yeah, if you look, it’s been used for so many different things. Sorry, I can’t give you more examples, but Yeah, I’m in the bee world too much. Bri: Awesome. You got some other comments about how great your presentation was, and that this will be, really impactful research. If there are no more questions, , Molly’s email’s on the screen, so you’re welcome to email her with other questions later, thank you all so much for attending this webinar. Before you close your browser, you’ll be prompted for that short 5-question education and outreach survey, this is the last of our eight webinars in this 2025 webinar series, and this has been recorded, so it will be posted on our YouTube channel @wsubeeprogram, so you can tell your friends about it if you’d like, , to share it with them. I’ll also be sending out a follow-up email with the link to the YouTube, video once it’s uploaded. And we will be doing another webinar series in 2026, so keep your eye out for, emails from me or our social media posts about our next webinar series. Thank you so much for attending. Molly: Awesome. Thanks so much Bri. | Title reads: Questions, comments, ideas? |