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| All right, it looks like we are not getting any more new people coming in so we are going to go ahead and get started. Thank you all for coming. I’m Bri Price, the WSU Bee Program extension coordinator. This is our first webinar of 2026, we have 3 more planned for this year. If you are interested in what those are about or to register, visit our upcoming events page on our website bees.wsu.edu. I just have a couple announcements before we begin, and then I’ll introduce today’s speaker. 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 that are pivotal to our food security and environmental health. In partnership with the CAHNRS Resilient Washington Initiative, we’re committed to advancing sustainable practices and pollinator-friendly landscapes, as well as ensuring a flourishing future for agriculture and natural resources. There will be time to answer questions after the presentation today, so feel free to type questions into the Q&A box below anytime during the presentation. After the event and before you close your browser, you should be prompted to answer a short five-question education and outreach survey. Your participation in this will really help us understand our impact today. Today’s speaker is Dr. Ryan Kuesel. Ryan is a postdoctoral researcher in our WSU Bee Program. Ryan is originally from Holland, Michigan, and he earned his PhD at the University of Kentucky in the Gonthier Lab, studying berry pest management. At WSU, Ryan has partnered with commercial apiaries to inspect their hives for signs of disease and to monitor their growth. He’s also educated current and future veterinarians about honeybee diseases. Ryan’s current major project aims to better understand European foulbrood. In this webinar, Ryan will outline whether we found differences in European foulbrood infections or honeybee colony strength in commercial colonies that were or were not in blueberry pollination. This data is one part of a multi-state project funded by an SCRI grant where migratory honeybee colonies were tracked as they were moved between crops, almonds, apples, blueberries, brambles, sunflowers, and canola. In 2023 and 2024. Today, you’re going to get a first glance at this project’s results. I’m going to go ahead and hide my screen, and you can share your screen, Ryan. | Woman with brown hair on screen wearing red glasses and a Washington State University Logo in the background. |
| Oh, yeah, thanks so much for the great introduction, Bri. And thanks everybody for coming today. So like Bri said, thanks so much for the introduction. Looking at the incidents and colony impacts of EFB in the Pacific Northwest based on that four‑state study that we’ve done 2 years out of 5 years so far. | The Washington State University Honey Bees and Pollinators Logo. The first slide heading reads, Incidence and Colony Impacts of European Foulbrood in the Pacific Northwest, Ryan Kuesel Ph.D., WSU Entomology, Honey Bees & Pollinators Program, Washington State University. Beside the text on the right, is the logo for the WSU Honey Bees and Pollinators Program. |
| So a quick overview of this webinar. I’ll cover what European foulbrood is as a bacterial species, and what its symptoms look like in a colony first to get us all on the same page about what European foulbrood is. I’ll then also go into how it causes damage inside of bee larva. And then go into why some beekeepers and researchers talk about it in association with blueberry pollination. Then I’ll give an overview of what we know from what we’ve currently done in the 2024 to 2027 four‑year or four‑university study that I collaborated on. Our fieldwork is done, but the laboratory work is just getting started and moving forward. And then I’ll give an update on the results of the fieldwork that we performed so far, at least what WSU had collected in the field data‑wise, before giving a conclusion about what this all means and then what’s to come, what y’all should look forward to in the future out of this project. | The next slide heading reads, Webinar Overview. Dr. Kuesel reads the bullets as he describes what will be covered in the webinar. |
| Alright, let’s dive into European foulbrood. You probably all know that European foulbrood is caused by a bacterium that’s Melissococcus plutonius. There’s a second foul brood called American foulbrood, which is devastating to a colony, much more so than European foulbrood, but this work, again, is about European foulbrood and not about American foulbrood. European foulbrood is shortened, often abbreviated to EFB as the acronym, so you’ll hear me say EFB a lot. It’s a lot fewer syllables to say throughout the webinar, meaning European foulbrood. | The next slide heading reads, Bacterial diseases, and two images of bacterial cells are shown. Under each is a journal citation. A green circle with the words, European foulbrood, appear on the left image and a red crossed circle with the words American foulbrood appear as Dr. Kuesel explains the webinar will cover European foulbrood, not American foulbrood. |
| So EFB infects larva at a young stage and kills them before they’re capped off by nurse bees. So unlike American foul brood, which kills the larva after they’re capped off, you’re going to see your symptoms and your larva die when they’re still larva as they’re growing before the capping happens by those nurse bees. | The next slide heading reads, EFB Infects Larvae. An image shows 7 stages of brood maturation. The first cell shows a queen laying an egg and is labeled, egg (day 1-3). The second shows 3 increasingly larger larvae and is labeled, larva (day 4-9). The third shows a large fifth instar larvae and is labeled, larva (capped) (day 0). The fourth shows a white pupa and the fifth shows a darker colored pupa. Both pupae are labeled, pupa (day 10-20). The fifth shows an adult bee and is labeled, adult (day 21). |
| But EFB is quite a weird sort of enigmatic disease because it seems to come and go with the passing of seasons. EFB symptoms are much worse in late spring and early summer, and especially in the Pacific Northwest, it seems almost ubiquitous that you’ll see a little bit of EFB, or a lot, hopefully not, but you may see a lot in your colonies. Publications as far back as about 1961 mentioned that sudden outbreaks of EFB are followed by a spontaneous recovery a few weeks later, meaning that you may get a sick colony that recovers on its own, with or without treatment, which is antibiotics, one specific type of antibiotics for this, oxytetracycline. And as we’re learning more about EFB in the modern day, we’re slowly finding patterns as to when and maybe why EFB symptoms emerge in colonies. One paper out of 2010 taught us that the outbreak of EFB disease seems to be linked to colony stressors, especially or including a lack of good quality food, so that may be one key to EFB. | The next slide heading reads, European foulbrood. Two images appear, one showing larvae that are discolored brown and the other showing a larva that is falling out from its cell due to European foulbrood disease. Dr. Kuesel reads the bullet points which explain that European foulbrood is an enigmatic disease that has seasonal outbreaks of symptoms. Their outbreaks tent to be sudden but can be followed by spontaneous recovery later and outbreaks are theorized to be linked to colony stressors like a lack of food. |
| And recent research has shown that the bacteria that causes EFB, Melissococcus plutonius, is sometimes present in colonies regardless of whether they’re displaying symptoms or not. There’s a study out of 2024 by Mallory and colleagues at the University of Guelph in Canada who looked at EFB in colonies and said that although the presence of that bacteria is associated with EFB symptoms, it does not consistently predict the manifestation of symptoms, meaning that just because that bacteria is present in a colony, it doesn’t mean that that colony will show symptoms. And that’s emphasized here in a second study in 2025 when Peter Fowler and colleagues from Michigan State University looked for EFB bacteria by searching for their DNA in migratory colonies. And when they found EFB bacteria in a given colony, only 28% of those colonies with bacteria were showing symptoms at the time they were sampled, while the remaining 72% of infected colonies had no symptoms of EFB while they still had that bacteria present. And that was out of almost 300 colonies inspected. So not only is EFB strange and difficult because it comes and goes with the seasons. It’s also weird that the bacteria seems to need maybe some sort of additional factor to let them take over a larva and show symptoms in the colony. That’s why I’ll often talk throughout this webinar in terms of seeing or not seeing EFB symptoms more so than seeing EFB infection, because being infected and seeing those deleterious symptoms is not one and the same with this strange bacterial disease. | The next slide heading also reads, European foulbrood. The same two images as appeared in last slide showing larvae that are discolored brown and the other showing a larva that is falling out from its cell due to European foulbrood disease. Dr. Kuesel reads the bullet points which explain that the presence of Melissococcus plutonius does not directly predict EFB symptoms and that a 2023 study from Michigan State University showed that 82% of colonies were asymptomatic despite the presence of M. plutonius bacteria in the colony. |
| Here’s the causal agent again. It’s Melissococcus plutonius. It looks like this on the right with multiple circle‑shaped cells often stuck together in a line as they’ve divided outward in a line. Here’s the causal agent again. It’s Melissococcus plutonius. It looks like this on the right with multiple circle‑shaped cells often stuck together in a line as they’ve divided outward in a line. Here, there’s four different Melissococcus bacteria or cells smashed together in one line, and it’s not spore‑forming as a bacteria. Luckily, it’s much easier to kill than American foulbrood, and you can sanitize your equipment much, much easier for this European foulbrood than American foulbrood because it doesn’t form spores. It’s also microaerophilic or entirely anaerobic, meaning that it can’t survive in environments with high levels, or any oxygen. So instead, it needs to survive in really oxygen‑poor environments like bee bread, honey, or the inside of a larva, of course, or maybe inside of the soil, which a few studies, just a few have started to show. | The next slide heading reads, European foulbrood pathogen. A microscope image of bacterial cells is shown on the right under the label, Causal agent: “Melissococcus plutonius”. Bullet points reiterate that European foulbrood is caused by a bacteria in the sepcies Melissococcus plutonius, which is in the family Enterococcaceae and that it is a non-spore forming, gram-positive, lanceolate coccus bacteria that is microaerophilic or anaerobic. |
| Larvae are infected with that EFB bacteria when they eat royal jelly or bee bread that contains those bacterial cells. And the bacteria begins to colonize the midgut of the larva really rapidly, and as they multiply in the midgut of infected larva, they compete with that larva for food and end up starving out that larva. | The next slide heading reads, European foulbrood infection. An image shows larvae that are discolored brown falling out from their cell due to European foulbrood disease. Bullet points read that larvae ingest bacteria from infected brood food colonizes the midgut, that it competes for nutrients with the larva, causing starvation, and that larvae are always susceptible, but older larvae are less susceptible. |
| So in weaker larva, the bacteria will take over the midgut completely. The larva will change color from a healthy pearly white, you see nice healthy larva on the left, nice white color, and they’re even in what looks like very new comb; it’s a light color, to an increasingly yellow, almost brown larva, as you can see here in the right image. It’s almost like a progression if you go right to left on this middle column where they start out sort of yellowish‑white, then darker, and then these larvae actually start to break down. This larva is dead at this point, and the body’s just collapsing before it finally turns into this brown, almost scale, loosely stuck to the bottom of the cell. You can see, typically with this, because of the body discoloration, a net of white trachea (that’s the respiratory system in these larva) running throughout it. But if you have this sort of deflating, sickle‑shaped or C‑shaped larva, the larva falling forward out of the cell and then finally deflating, you likely have European foulbrood. And then, while removing this scale or here, a much more dried‑out scale the mouthparts of nurse bees can become infected with the European foulbrood bacteria, and they can transmit it throughout the colony. | The next slide heading reads, European foulbrood symptoms. The same image as before shows larvae that are discolored brown falling out from their cell due to European foulbrood disease. A second image to its left shows healthy white bee larvae. Bullet points read that larvae turn yellow then brown, revealing white trachea, before they, twist outward in the cell, and turn “semi-liquid”. The last bullet notes larvae usually die on day 4-3 of infection. |
| So Melissococcus plutonius weakens the larval gut microbiome, also allowing secondary infections of bacteria like Achromobacter eurydice, Enterococcus faecalis, and Paenibacillus alvei. And it’s thought that one or multiple of these contribute to a bad smell that’s sometimes found with EFB cases. | The next slide heading also reads, European foulbrood symptoms. Three microscope images of bacterial species are shown. Each is labeled, Achromobacter euridice, Enterococcus faecalis, Paenibacillus alvei. Dr. Kuesel reads a new 3th bullet that is connected to the 3 bacterial species with a bracket. The text indicates one or more of the secondary bacterial species may be responsible for a foul odor sometimes found in European foulbrood cases. |
| Then, the death of some larva but survival of others leads to what’s known as a shotgun brood pattern. You can see that clearly here. Some larvae have died out, while others are in their final stage before getting capped, and some have survived up to the capping phase. That’s a common symptom of a lot of different diseases, so you’ll have to also look for the state of those larvae; look for those drying up yellowish‑brown larva as well. And again, it may or may not have a foul odor if it has an association with those other secondary infectors. The royal jelly might also be discolored. If you can see deep down in that cell with a good light, the royal jelly is yellowish or almost brownish, meaning the royal jelly fed to this larva by a nurse bee is infected with that foulbrood, and the larva is going to get infected by eating it. | The next slide heading also reads, European foulbrood symptoms. They read, shotgun brood pattern, royal jelly discolors yellow or brown, often but not always foul odor in hive. An image of honeybee brood with sparce maturing larvae and pupae is shown as Dr. Kuesel explains “shotgun brood”. That picture is replaced with a picture of very small honey bee larva and eggs is shown. One larva is yellowish colored and it is sitting in a pool of brood food that is also discolored yellow. 3 new bullet points are revealed. |
| So, of course, the way that EFB gets into the larva is through feeding. When royal jelly or bee bread enters the mouth, it first moves through the pharynx and into the esophagus, which are muscular tubes that assist in swallowing food and moving it deeper into the body. It then enters the mid‑intestine, which is a huge pouch; about a third of the thickness of each larva. So, most of the larva is this midgut. That structure digests the food and diffuses nutrients across its walls into the hemolymph, which is the blood of insects, and that’s how the larva gets nutrients. Then the food moves into the hind intestine, where water, salts, and amino acids are removed, feces is formed, and it’s excreted. | The next slide heading reads, Digestive system. An image of the internal digestive system of honey bee larva is shown, and arrows connect labels to each structure. Dr. Kuesel reads the labels and their respective functions. |
| But as we know, EFB infects the larva in the midgut. This very large organ responsible for capturing nutrients is what gets infected. | The next slide heading reads, Where’s the EFB Action. An image of the internal digestive system of honey bee larva is shown, and one arrow connects the label for mid intestine/midgut to the structure. |
| EFB bacteria start growing between the food mass in the hollow middle of the midgut. You can see in image A. The L is lumen, the center of the midgut. There’s probably food in there. But what we see stained is these red European foulbrood cells and purple larval gut cells. The bacteria are directly attaching to epithelial cells of the gut. The EFB cells use up the nutrients that would normally feed the larva’s own growth by blocking absorption across the gut membrane. As they steal nutrients, they reproduce and colonize all of the gut, as seen in image C. The entire center of the midgut is infested with European foulbrood. And while colonizing the gut, they’re also producing enzymes that dissolve the gut wall of the larva. | The next slide heading reads, EFB Disease Cause. The midgut is enlarged to show a 4-panel figure of microscope images. Panel A shows limited red-stained M. plutonius bacteria on the inner edge of a ring of purple stained gut cells. Panel B shows a different cross section of the same. Panel C shows the entire center area of the mid gut filled with red bacterial cells and Panel D shows a closeup of the same. |
| If the larva is strong and well fed, it might survive until pupation even while infected; they can live to adulthood but typically come out as slightly smaller adult bees. But if the larva is very weak and not well fed, then the EFB succeeds at fully starving the larva, and it will die before the cell wall is capped. That means EFB usually kills its host larva and invades the tissue outside the gut after its death. Once the larva is dead, the bacteria and other secondary invading bacteria use what’s left of the body, continue to discolor and dry out the cell, and then wait for a nurse bee to pick it up and spread the bacteria. | The next slide heading also reads, EFB Disease Cause. An image shows discolored brown larvae that are falling out from their cells due to European foulbrood disease. |
| So, if you need to identify EFB in a hive, and this is what we looked for in our study, remember EFB kills larva before the cells are capped. You’ll see yellowish or brownish deflating larva in open cells, often with that net of white trachea running through their bodies. You’ll sometimes smell a sickly sweet, almost sour urine smell, but not always. Don’t mistake it for American foulbrood, though. American foulbrood kills the larva once they’re capped. You’ll see capped cells sinking inward. These caps sink down, not out. You may see liquid bacterial inoculum, that orange liquid, emerging. And if you do a matchstick test, insert a stick into the cell and stir, you can pull out a rope of larval goo if it’s American foulbrood. EFB can have a little ropiness, but not nearly as much. | The next slide heading reads, Field Identification of EFB. An image shows discolored brown larvae that are falling out from their cells due to European foulbrood disease. A list of symptoms for European foulbrood is shown on the left and reads, kills larvae before capped, yellowish/brown larvae, sometimes smells, and sometimes stringy. A list of symptoms for American foulbrood lies below and reads, kills larvae after capped, sunken and leaking brood caps, always smells, very stringy. A second picture replaces the last showing capped bee brood with spaced-out capped cells amidst empty cells. The cell caps are sinking in, and some show a reddish liquid of bacterial inoculum above the caps. A third picture replaces the last showing the “match-stick test for AFB”. A long string of crushed larva is being pulled from a section of capped brood on a matchstick. |
| All right. So we’ve all learned, or maybe been reminded about what causes EFB. Let’s switch over to looking at why symptoms and damage in colonies happen. | The next slide is only a heading that reads, That’s WHAT causes EFB. Now WHY do symptoms and damage happen? |
| Back at least in 1991, honeybee pathologists Leslie Bailey and Brenda Ball were asking that same question, and they found that the number of infected larvae in colonies was highest when the overall population of brood was high. Here they sampled the number of sick larvae in a colony over two years. The black circles are Year 1, peaking around mid or late June into early July. The same pattern is seen in Year 2, though Year 2 had fewer EFB‑infected larvae. The triangles above show the overall number of larvae (on a separate scale). What’s important is that they peak at the same time. They suggested that when nectar flow begins in early spring or late June into July, brood production takes off while fewer bees remain nurses, because they’re being pushed into foraging roles earlier. That decreases the amount of brood food each larva receives, and with fewer nurse bees feeding more larvae, larvae are more likely to starve and die to EFB. Further, there are fewer nurse and undertaker bees to remove dead larvae from the colony. So, more bacterial inoculum accumulates in those larval bodies sitting in cells. Altogether, they hypothesized this could lead to greater EFB presence in late spring and early summer. | The next slide heading reads, Population Dynamics. A graph shows lines that starts low in May, rises to a peak between June and July, and then falls back down in August. The lines are labeled “Sick Larvae 1”, “Sick Larvae 2”, and “All Brood”. Dr. Kuesel describes the figure and then reads text next to the figure that describes how a 1991 manuscript hypothesized EFB symptoms may be linked to high overall brood populations because there are too many larvae for the available nurse bees to feed when nectar flows strengthen. |
| So one of the earliest crops that needs bee pollination in the Pacific Northwest is blueberry. Bees often come back from California almonds that maybe get split into two and then treated for varroa, and then around late April, they’re moved into blueberries for pollination. Or they might get moved into apple, or cherry orchards, which are also blooming at about the same time. But for a bit now, beekeepers have expressed some concerns that their bees seem to get European foulbrood more, or at least express symptoms of EFB more when they pollinate blueberries, and that ends up setting those colonies back for future pollination jobs and summer honey collection. That’s a pretty concerning possibility for beekeepers and blueberry growers alike in the Pacific Northwest. It’s a huge portion of America’s blueberry production is done where we are in the Pacific Northwest. So we started looking to see if there’s a link a couple years ago. | The next slide heading reads, EFB and Blueberry Pollination. One image shows palatized blue bee colonies in the middle of a blooming blueberry orchard. Below that, another image shows two bee keepers inspecting bee colonies in the middle of a blooming blueberry orchard. |
| After brainstorming at the start of our study, we thought of several things that we need to look at as a possible reasons why EFB symptoms could emerge in blueberry pollination. It could be that the nectar flow from blueberries indeed is spurring that high brood production, and having more foraging, causing larva to go hungry and die, and then not be removed as fast as they need to be, like Bailey and Ball suggested. Blueberry pollen also has very low protein and essential amino acid content already. So, bees pollinating blueberries might experience that nutritional stress in that way, leading to weaker larva, who’s maybe immune systems can’t fight off the EFB bacteria. Fungicides are used at high levels as soon as blueberry flowers drop to protect those new growing blueberries from a lot of different fungal diseases. So, bees that aren’t removed from blueberry plots fast enough and are there into blueberry formation might be exposed to fungicides, which we’re learning now actually can maybe disrupt the larval gut microbes inside of bees, which would interfere with their ability to digest and capture nutrients, and could cause those larva to starve even more quickly in the face of EFB infections. In that time of year is still pretty cold in the Pacific Northwest, or at least it can be, especially at night. So broods could be developing slower due to that cold weather, giving EFB more time to spread and multiply in each larva. Then maybe different blueberry blossoms, or the soil around blueberries might harbor a different or more virulent strain of EFB than other crops. That one would be hard to prove, or perhaps the high acidity of blueberry pollen could acidify the gut environment of the larva, making it more hospitable to EFB bacteria. Blueberries are acidophiles. They love acid, and their pollen represents that through more acidic pollen. | The next slide heading also reads, EFB and Blueberry Pollination. One image shows palatized blue bee colonies in the middle of a blooming blueberry orchard. Dr. Kuesel reads a list of hypothetical reasons European foulbrood symptoms rise in blueberry pollination. The list is: Nurse Bee to Brood Imbalance? Low Forage & Nutritional Stress? Fungicide exposure? Brood chilling? Different strain of EFB? And Acidic pH of Blueberry Pollen? |
| Then compounding all those possibilities is the fact that splits are typically made just before blueberry pollination and leaving splits, making splits leaves colonies with less pollen and honey stores between the two of them. So for folks who are unfamiliar with splits, making a split is just when you take one colony and split it into two by removing about half the brood, the bees, the pollen, and the nectar stores from the original colony, putting them into a new colony. And then you have two different colonies, and you give this new colony a new queen or let it re-queen itself if you’re doing walk away splits. | The next slide heading reads, Making Splits / Dividing Colonies: Could splitting result in nutritional stress to larvae? A picture shows two 5-frame bee boxes laid out next to either as a beekeeper adds frames of bees and brood to each, creating two splits. |
| And we do know already from a previous work actually by several of the collaborators on this current study that blueberries provide low quality or low quantities of already low quality, like poorly nutritious pollen compared to other crops. This is a study from published in 2019, that, was summarizing the work over the previous several years from that. | The next slide heading reads, Lack of adequate pollen in the landscape. The cover page of a manuscript is depicted. It reads “Journal of Economic Entomology – Apiculture and Social Insects.” “Assessment of pollen diversity available to honey bees (Hymenoptera: Apidae) in major cropping systems during pollination in western United States. The authors are Ellen Topitzhofer, Hannah Lucas, Priyadarshini Chakrabarti, Carolyn Breece, Vaughn Bryant, and Ramesh R. Sagili of Oregon State University. |
| It found that of several early season crops, including meadow foam, cherry, almond, highbush, blueberry, and hybrid carrot. Bees collected very little pollen in that high bush blueberry environment. And that was measured using pollen traps that remove the corbicular pollen from bees as they’re entering the colony. In blueberries, bees brought us back about 81 grams of pollen per week compared to meadow foam, or a great pollen source that has about 693 grams per week per colony. Cherry had about 533 grams per colony per week, and almond had 303 grams per colony per week. That would have to take place before the blueberry and cherry and meadow foam. In hybrid carrot, it was the worst of all of them, they don’t produce very much pollen. | The next slide heading also reads, Lack of adequate pollen in the landscape. Dr. Kuesel reads the weights of pollen collected per colony per week in 5 pollination crops from the study. |
| And that led us into our 4 statewide and 4 university wide multi-year project. | The next slide is only a heading that reads, Four-State-Wide Project. |
| This the team at Oregon State, headed by Ramesh Sagili was awarded the Specialty Crop Research Initiative in 2024 for a whopping $4.2 million dollars. So thanks for the USDA for funding us on that. And that funding was split amongst multiple professors at four different universities. All these folks are from Oregon State, Washington State, Mississippi State, and then University of California at Davis. And together, while 8 of these professors and each of their teams plan to look at several of the possible reasons why those EFB symptoms might emerge in blueberries. | The next slide heading reads, USDA SCRI Funded Project. The subheading reads, Evaluating and Mitigating European Foulbrood Disease in Honey Bees. The images of 8 faculty members at Oregon State University, Washington State University, University of California Davis, and Mississippi State University. The faculty members are Ramesh Sagili, Brandon Hopkins, Elina Niño, Priya Basu, Jeff Chang, Maude David, Tim Delbridge, and Andony Melanthopoulos. Two images of the team standing and working together in a blooming almond orchard are shown below. |
| The objectives of our massive study were to determine the factors associated with EFB symptom prevalence and intensity. Evaluate techniques to manage European foulbrood. investigate genetic variation in EFB bacteria in colonies pollinating early season specialty crops. And then develop effective EFB management practices at the very end of all of this work. | The next slide heading reads, Objectives of Study. Dr. Kuesel reads the 4 bullet points containing the objectives. |
| So if we do indeed find an association with EFB symptoms and blueberry pollination. What we really expected to find and still expect to find is that there’s not really one direct reason causing that increase in symptoms. We expect that blueberry pollination, like, maybe comes at a poor time of year with inclement weather that causes that brood chill slows down brood production. And then a lack of adequate pollen in the in the blueberry landscape combined with a lack of optimal foraging weather due to that inclement weather and too few nurse bees for the amount of larva that they’re producing might all lead to poor larval nutrition and cause some of those symptoms. And then fungicide exposure if colonies are left past petal fall and into the fruiting period, would be an additional contributor, possibly. | The next slide is a diagram showing different factors connected by arrows. A yellow box labeled, almonds with a drawing of a beehive and a note that says, no EFB symptoms. A green box labeled inclement weather with a small snowflake and bee icon, leads to a smaller box labeled brood chill. A purple box labeled fungicide exposure has a picture of a chemical sprayer. Around the bottom half are three curved sections connected to a red center. They read “lack of adequate pollen in the landscape”, “lack of optimal foraging due to inclement weather”, “skewed larvae to nurse bee ratio.” The red center reads “Poor larval nutrition. The boxes containing, poor larval nutrition, brood chill, and fungicide exposure all point to a blue box in the center of everything labeled, blueberry with a beehive and a frame showing , EFB symptoms.” |
| So the experiment that we’ve already completed now in the 1st 2 years of 2024 and 5 was to move colonies along a typical migratory pollination route. Where half of them in May in the second period would go to blueberry pollination and half of those would go anywhere but blueberries for that period. Each university partnered with several commercial apiaries to get this done, and we moved bees that we owned as well along this path. And we and our partner beekeepers moved colonies from each state out to California for almond pollination in late January, early February. And then we inspected the colonies a couple weeks later right at peak bloom, in February. Once the bloom had all subsided, we moved half of those colonies to a blueberry pollination down below in our respective states, while the other half were instead moved to a different specialty crop, or most often, especially for WSU, they were moved to a holding yard for that period of time. And we inspected those at the end of blueberry bloom, but in both locations right around May, and then moved them out before fruit sat in that blueberry into another holding yard, or another specialty crop for pollination in our third inspection period. We inspected that third inspection in July and then moved those to their final overwintering location where we inspected them just before winter in October as our 4th inspection. We let all of those colonies overwinter as normal and then repeated the process again back in late January, early February, by moving them out to California almonds, and then doing the same pattern where those same blueberry colonies were moved to blueberry, and the others were moved to not blueberry. And throughout the 2 years, as colonies died out, we removed them from the experiment and continued on with the smaller cohort so that we were tracking the same colonies for both years across 8 total inspection periods. | The next slide heading reads, Experimental Design (Longitudinal Study). A flow chart shows boxes from left to right. The first box reads “California almond pollination”. Two arrows point right to a box reading, Specialty Crop “X” Pollination or holding yard above a box reading, blueberry pollination. Arrows leave those boxes and converge on a box reading, specialty crop “Y” or holding yard. An arrow leaves that box and points to a box reading specialty crop “Y” or holding yard. An arrow leaves that box and points to a box reading California almond pollination. Each box has another green arrow pointing to a central box reading Perform Colony Evaluations, (clinical levels of brood, disease, bee population, brood area, pollen stores, etc.), and sampling: Larvae nurse bees, pollen, and wax. |
| So here’s what our very coordinated first sampling looked like in almonds in 2024. All four university teams worked together on these first colonies out in around San Joaquin Valley of California, and that was in February, two years ago, 2024. We learned the ropes of sampling and data collection as a group all together, so we were on the same page. | The next slide is an image of the quad-university team inspecting colonies together in a blooming almond orchard. |
| We opened up each colony at every inspection point and measured the bee population as the frames that were covered in bees. And we pulled every frame out as well and quantified what percent of each frame was covered in open brood, eggs and larva, and what percentage was covered in cat brood? So here we’d say, maybe this is about 90% coverage, maybe 85% coverage of that capped brood, and there’s probably… you’d have to look in a better light, some larvae around here, maybe 5-10% of open brood. We do the same on the back and then do all the frames throughout the colony. We also recorded EFB scores. So is on a scale of 0 to 3. 0 meant that there were no infected larvae in the whole colony. One meant there were about 1 to 10 larvae in the whole colony infected. 2 meant 11 to 50 colony or larvae were infected in the colony, and then a 3 score of 3 meant 50 or more larva in that colony were infected. So that was a good way to say how severely these colonies are infected or not at all. That’s only possible if we had larva to look at as well, so at some point you’ll see some of these colonies we weren’t able to diagnose EFB symptoms in, because there simply weren’t larva. | The next slide heading reads, Colony Evaluations – Bee population, brood area (capped and open) and EFB score. An image of a brood frame filled with capped brood and covered in bees is shown. |
And we sampled healthy larva carefully without popping them at all, without damaging their fragile larval bodies. We scooped them out with queen grafting tools and forceps, and then added them to a vial, and then put them directly onto negative 80 Celsius freezing conditions with dry ice, and stored them to be analyzed later on for what strains of EFB bacteria are present inside of them. | The next slide heading reads, Colony Evaluations – PCR Detection, Culturing, Whole Genome Sequencing. An image of a bee larva being placed in a vial using forceps is shown on the left. On the right is an image of a larvae being scooped out of a brood frame with a queen grafting tool. |
| And then we also took samples of nurse bees for multiple reasons for a head protein count to look at how much protein or vitellogenin is present in the head of these bees, which can directly link to how much. brood food they can make, and how nutritious of that royal jelly brood food that the larva can make, as well as to dissect them out and look at what bacteria are present inside of their guts as adults. | The next slide heading reads, Nurse Bee Sampling – Head protein content and Vitellogenin analysis and Gut microbiome diversity. An image of a brood frame filled with capped brood and covered in bees is shown on the left. On the right is an image of a scientist sampling a cup of nurse bees off of a brood frame. |
| All right so here’s the results so far. This is just data from those inspections that that we undertook at WSU. There’s more data from the additional universities that we will look at in future talks, and if we look at Oregon State University for those talks and more. | The next slide is only a heading that reads, Results So Far Colony Inspection Data from WSU-Inspections. |
| So 1st up, this is just colonies with symptoms. This means the colony had symptoms at any point, and any of the 8 inspection periods. We split it into blueberry versus non-blueberry going colonies. We have symptomatic here at about 30.3%. in the blueberry pollination group versus 32.3% were symptomatic for EFB in that non-blueberry group. That’s pretty much exactly even. And then, with the non-symptomatic, they’re approximately even as well, about 69.7% in the blueberry group, 67.7% in the non-blueberry group. So already that was kind of surprising that we did not really see a difference at that coarse level for colonies that were ever infected showing EFB. But that’s over 2 years of time and 8 inspection periods combined into one. | The next slide heading reads, Colonies with Symptoms. A bar chart with 4 columns is shown. The left two columns are labeled blueberry and colored blue. The leftmost column shows 30.3% of colonies used to pollinate blueberry were ever symptomatic with EFB. The column to its right shows 69.37% of colonies used to pollinate blueberry were not ever symptomatic with EFB. The right two columns are labeled non-blueberry and colored red. The left column shows 32.3% of colonies never used to pollinate blueberry were ever symptomatic with EFB. The right most column shows 67.7% of colonies not used to pollinate blueberry were not ever symptomatic with EFB. |
| This splits those out among the 8 inspection periods across the 2 years into 5 columns or green is 0. There was no EFB located or identified. One is yellow, where there’s few larva. 2 is a little more larva, and 3 has that large infection of 50 plus larva infected. And then some of those had no larva for us to identify, so we had to put that in a separate category looking 1st at February. We were surprised to have a couple colonies, about 3 colonies that we suspected had that EFB infection, but at a pretty low level, about a 1 for 2 of those colonies, and a two for one of those colonies. That shows that EFB can happen outside of that peak season of late spring and our May survey. This is into that right at the end of blueberry pollination. We’re starting to see what we suspected was more EFB in these colonies, with some even reaching that third level, 15 of those colonies. Had that third level of highly infected with what we suspected was EFB. 34 colonies are at the level of two and then 26 were at the level of one. So EFB seem to be peaking there. This was late May. Then we skipped June and went into our July survey when they’re in that next crop or holding yard. We see the level of EFB is about the same, but starting to starting to go down a little bit, especially those ones and twos. And then no larva still. Both of them have about 24 colonies with no larva. So May and July is our peak. Maybe likely was peaked right in the center of both of these inspection points. In October, we see very few colonies that still had European foulbrood symptoms. And with some of these, I would be suspicious that it may not be EFB, but may instead be colony collapse of a different variety, like a parasitic mite syndrome, where there’s too much Varroa, and you’re seeing sort of similar symptoms, but maybe we misdiagnosed those in the field. And then over winter into February. We have very few again, just one and one. And now we’re seeing that cohort really, really decline. Very few colonies survived into the second year. That’s shows how difficult beekeeping is, especially when we’re not using antibiotics to treat for this disease. In May, we’re peaking with our very few colonies still, you know, just 3, 2, and 1 in that increasing severity category. And then in July we actually found no symptoms. So it seems like we had a good year. Maybe those bees were able to feed well and survive throughout that summer and beat off the EFB disease. Then in October, again, we see some that we suspected were full of were infected with EFB, but maybe a different disorder. | The next slide heading reads, EFB Scores Across Eight Surveys (percent). A bar chart with 8 separate sections shows the number of colonies that had active EFB symptom scores of 0, 1, 2, 3 or had no larva to judge infection status within each of the 8 sampling times. The majority of colonies always had scores of 0. Dr. Kuesel identifies some peak periods with symptoms while symptoms were largely non-existent in the other sampling periods. Those are as follows: May 2024 and July 2024 sampling had between 14 and 34 colonies per symptom score 1, 2, and 3. May of 2025 had between 1 and 3 colonies per symptom score 1, 2, and 3. |
| Now let’s split those into blueberry versus non-blueberry, and we’re looking at the percent of colonies within that blueberry group, and the percent of colonies within that non-blueberry group. And this is just the 1st year of inspection points. In February, very few that just show any EFB symptoms at all. So 1, 2, or 3 on that scale. In May, we’re peaking at 32.1% of EFB symptoms in blueberries, a little bit elevated compared to our non-blueberries at 22.5% colonies infected in May of 2024. So we have a little bit of differential there, a little under 10% more colonies infected in that first year in the blueberry colonies. Then following that up, as the colonies are beating off EFB and healing up, we have a 20.5% with EFB symptoms and blueberries, and about the same, 20.1%, with EFB symptoms and the non-blueberry goers. And then finally into October, we see a little bit more of that EFB might be hanging around if it’s not a red herring. Whereas our non-blueberry going colonies have none. | The next slide heading reads, EFB Symptoms in 2024 Inspections. A bar chart is shown containing two columns with 4 rows. Columns show each individual sampling period. The left column shows colonies used to pollinate blueberries that didn’t have active symptoms, had active symptoms, had no larvae, or were deadouts while the right column shows the same data categories for colonies never used to pollinate them. Both rows show similar data, with one key difference being that in May, 32.1% of blueberry colonies had EFB symptoms and 57.7% did not, while 22.5% of non-blueberry colonies had EFB symptoms and 70.3% were not symptomatic. |
| This is into year two, 2025, where we have very few colonies, but are still seeing there might be some EFB at the start. Are we having a little bit of EFB symptoms in blueberry, and strangely more in our non-blueberry crops this year before moving into July, where it seems to cure itself and heal up, and then we go back into maybe some of those false flags or red herrings in October. It is still possible that EFB, though. I should stress that. | The next slide heading reads, EFB Symptoms in 2025 Inspections. A similar bar chart to the prior slide is shown. Both rows show similar data, with one key difference being that in May, 3.4% of blueberry colonies had EFB symptoms and 75.9% did not, while 15.2% of non-blueberry colonies had EFB symptoms and 78.8% were not symptomatic. |
| This is just in more detail looking across the 3 different categories of damage or severity in each treatment. I’m sort of laying that out in in more detail. That’s for 2024. | The next slide heading reads, Symptom Scores in 2024 Inspections. A bar chart is shown containing two columns with 4 rows. Columns show each individual sampling period. The left column shows colonies used to pollinate blueberries that earned a symptom score of 0, 1, 2, 3, or had no larvae, while the right column shows the same data categories for colonies never used to pollinate them. Both rows show similar data, and Dr. Kuesel covers key differences between the two. |
| And there’s for 2025, the severity scores. So it seems like so far there’s some variation between the two groups. It’s very hard to say if there really is a lot more in blueberry, but there may be a little bit, it seems. | The next slide heading reads, Symptom Scores in 2025 Inspections. A bar chart is shown containing two columns with 4 rows. Columns show each individual sampling period. The left column shows colonies used to pollinate blueberries that earned a symptom score of 0, 1, 2, 3, or had no larvae, while the right column shows the same data categories for colonies never used to pollinate them. Both rows show similar data, and Dr. Kuesel covers key differences between the two. |
| Now let’s look at the fate of symptomatic colonies. This is sort of getting at what’s the cost of European foulbrood infections overall. And this is regardless of treatment group. They may or may not have gone to blueberries in this group, and what each of these dots means is you’re moving from sampling round 1, 2, 3, 4 over winter, and then 5, 6, 7, 8. Meaning February, May, July, October, February, May, July, October. In green at a 0 is the EFB value or score of 0. That’s a healthy colony. Moving up to yellow, hopefully y’all can see it on your screens, the yellow at this level 1 is the level 1 infection, up to orange is 2, and up to 3 is red, and then down to negative 1 means it’s a black dot, it means that there’s no larva to judge this on. And so you can see a lot of these colonies are not making it super far into the season, and you can highlight what all exactly is happening here, where green means that. That colony has seemed to outlast the larva or alas, the infection of European foulbrood. Yellow means that it maybe died out due to European foulbrood. It made it 2 sampling points before dying, and there’s no points here, meaning that that colony’s died out, orange up here means that the colonies died out one had one sampling point, and then it died after that, based on when it was infected last, and then in red means that that colony was infected, and then the next time that we sampled it, it was gone, maybe likely died out to that European foulbrood. So I’d say if we look at this… black means that there were, it’s hard to tell because the EFB only occurred in our last sampling point. We don’t know the fate of that colony, because we stopped tracking it after those 2 years, and 4 of those colonies showed just those symptoms in the very last inspection in October. Green, 12 of these survived more than 2 surveys after the symptoms, which is about half of a year. That’s 21% of the colonies that I’d say overcame that infection. Then yellow 21 colonies survived exactly 2 surveys after infection. It’s about 37% that I say were maybe weakened by European foulbrood and maybe couldn’t survive in that weakened state. But maybe an additional stressor took out those weakened colonies. And that stressor very likely might be, especially in these blue highlighted colonies might be winter. So these colonies made it, you know, 4 periods, and most of them had an infection in that May sampling point, sampling point 2, they likely either died over winter, or maybe were combined by ourselves or by partner beekeepers with other colonies because they were judged to be too weak to survive over that winter in orange. Those survived just that that one survey after infection and then died. It’s about 18% that I say were likely weakened by European foulbrood and likely died as a result of that disease. And then in red, 10 of them died immediately after their infection was diagnosed, so that, that means quite likely in my eyes, these colonies died out to European foulbrood. | The next slide heading reads, Fate of Symptomatic Colonies. An 8 by 7 grid of small dot and line charts show the EFB symptom score for every colony that ever showed EFB symptoms in each time point. Each colony only showed symptoms once or twice. Each graph is surrounded by red, orange, yellow, green, or black, indicating the colony was dead in the very next inspection round after showing symptoms, lived for two inspections and was dead in the third after showing symptoms, lived for one inspection after showing symptoms and was dead in the following round, or showed symptoms only in the eighth and final inspection round respectively. A blue border appears surrounding yellow colony charts that first died in the February 2025 inspection round as Dr. Kuesel hypothesizes they may have died to winter struggles. The blue border disappears when Dr. Kuesel begins to talk about orange and red bordered charts. |
| All right. Next, let’s take a look at some of those metrics. And this is the frame of bees between the two treatments. For all these graphs from here on out, red means that they did not go to blueberry and blue means that they did go to blueberry. And we have our age inspection periods on the x-axis, and then the frames of bees, the number of frames covered in bees, on the y-axis up here. So as we’re going along throughout the season seems like the no blueberry colonies fared a little, or it started out a little bit stronger, maybe by about a frame of bees here. But in the May survey and blueberries or non-blueberries, they came back to about the exact same before it seems like about 2.8 frames difference occurred in those colonies that did not go to blueberry versus those that did go to blueberry. And again, this is usually these colonies and blueberries were moved to a different location for blueberry pollination, where in red, our colonies more than often stayed where they were and were left in a holding yard. It seems like these blueberry colonies didn’t recover quite as well going into October. That’s where we’re seeing our drop-off in bees, but a lot of these blueberry colonies are sitting at around 6 frames of bees, or actually, it looks like about 7, maybe six and a half frames of bees, where our non-blueberries are about 2.2 frames of bees higher than that. And that continued over winter still, where our non-blueberry colonies still seem to be a little bit stronger, about 1.5 frames of bees than that blueberry counterparts. And again, when they’re going up into blueberries, they’re differentiating by about 2 frames of bees, or 1.95, with those non-blueberry goers being stronger. Interestingly, when they went into July, they really converged back to the same level. We had low levels of EFB infection that year, so maybe that could be why there wasn’t a lot of damage from EFB in these colonies, and then down into October, we’re seeing our colonies are doing, very poorly without proper management of a lot of diseases in EFB across this this intensive study and intensive transport. | The next slide heading reads, Frames of Bees Between Treatments. A dot and line graph shows a red and blue line. The blue line represents the average frames of bees in colonies that went to blueberry pollination across the eight sampling points. The red line represents the average frames of bees in colonies that did not go to blueberry pollination across the eight sampling points. Both lines start low in February 2024, rise in May 2024, rise again to a peak in July 2024 before falling to its lowest level in October 2024. The same pattern is repeated in 2025. Four brackets show the non-blueberry colonies had 2.8, 2.2, 1.5, and 1.95 frames of bees more in July 2024, October 2024, February 2025, and May 2025 respectively. |
| So this is frames of open brood. We’re starting very tightly close with the frames of open brood at about one frame of total open brood in February at the end of almonds. They seem to diverge a little bit, about a quarter frame of brood difference here with that non-blueberry goers, still a little bit ahead before they come back together to be about the same in July, and then crashing down in October to almost no brood for that overwintering period together. Coming out of winter into almonds, got a little bit of separation again, 0.21 frames of open brood difference between non-blueberry and blueberry goers, and then into May, they really took off. It seems like those non-blueberry colonies were able to put on a lot more larval growth, larval production, compared to our non-blueberries, about 0.8 frames difference there, before converging again in July and into October. | The next slide heading reads, Frames of Open Brood Between Treatments. A dot and line graph shows a red and blue line. The blue line represents the average frames of bees in colonies that went to blueberry pollination across the eight sampling points. The red line represents the average frames of bees in colonies that did not go to blueberry pollination across the eight sampling points. Both lines start low in February 2024, rise in May 2024, rise again to a peak in July 2024 before falling to its lowest level in October 2024. The same pattern is repeated in 2025. Three brackets show the non-blueberry colonies had 0.25, 0.21, and 0.8 frames of open brood more in May 2024, February 2024, February 2025, and May 2025 respectively. |
| And then, finally, here’s our frames of capped brood. It seems like for the first 3, those error bars are overlapping, so there’s not a lot of difference. Maybe a little bit, maybe a quarter frame of bees difference in that May before they come up to about the same. and then back down to zero. And then in that second year, we actually are seeing a little bit of difference in that capped brood, about 0.4 frames difference in February, expanding up to that 0.74 frames of kept difference. So throughout this experiment, it seemed like our non-blueberry goers were had a little bit higher levels of bees, open brood and capped brood. Then our blueberry goers. But again, we have that, confounding variable that maybe it’s the movement of the colonies into the blueberry that caused that stress and that lack of bee production. | The next slide heading reads, Frames of Capped Brood Between Treatments. A dot and line graph shows a red and blue line. The blue line represents the average frames of bees in colonies that went to blueberry pollination across the eight sampling points. The red line represents the average frames of bees in colonies that did not go to blueberry pollination across the eight sampling points. Both lines start low in February 2024, fall slightly in May 2024, rise again to a peak in July 2024 before falling to its lowest level in October 2024. For 2025, both lines rise into February, rise again to a peak in May, and fall in July 2024 before falling to its lowest level in October 2024. Three brackets show the non-blueberry colonies had 0.25, 0.21, and 0.8 frames of open brood more in May 2024, February 2024, February 2025, and May 2025 respectively. |
| Alright. So now, instead of splitting them into blueberry goers versus non blueberry goers. We’ve got them split into infected versus non-infected. We’re infected is orange in gray is not infected. This is regardless of what treatment they went to, lueberries versus non-blueberries, and instead is, again, getting at the question of how impactful a foulbrood infection on colonies is. We see a large difference, and in this case they’re starting out at a pretty different point in May in terms of frames of bees, so I calculated the increase in frames of bees as they’re hitting their peak of population into July and August. And we see that those colonies that were not infected were able to put on quite a bit more frames of bees than those that had suffered an EFB infection at any point throughout the experiment. So, it seems like EFB can take off a couple frames of bees in that summer growth period in in these relatively smaller hives. And so that could be a critical point showing that EFB can damage your bee populations and weaken that colony. | The next slide heading reads, Frames of Bees by Infection Status. A dot and line graph shows an orange and grey line. The orange line represents the average frames of bees in colonies that ever showed EFB symptoms in any of the eight sampling points. The grey line represents the average frames of bees in colonies that never showed EFB symptoms in any of the eight sampling points. Both lines start low in February 2024, rise slightly in May 2024, rise again to a peak in July 2024 before falling to its lowest level in October 2024. For 2025, both lines rise into February, rise again to a peak in May, and fall in July 2024 before falling to its lowest level in October 2024. Two numbers lying along the lines show the infected colonies gained 0.97 frames of bees while non-infected colonies gained 2.74 frames of bees between May and July 2024. |
| We’re seeing the same pattern for open brood. And again, this disease kills your open brood, where moving from May into July with that big brood production increase, we’re seeing about, a half of a frame of open brood more being produced in May to July, as opposed to the infected colonies that just had very, very little growth, actually. It seems like they were very, very stunted in their larval growth, maybe because those larvae are dying out to that EFB. | The next slide heading reads, Frames of Open Brood by Infection Status. A dot and line graph shows an orange and grey line. The orange line represents the average frames of bees in colonies that ever showed EFB symptoms in any of the eight sampling points. The grey line represents the average frames of bees in colonies that never showed EFB symptoms in any of the eight sampling points. Both lines start low in February 2024, rise slightly in May 2024, rise again to a peak in July 2024 before falling to its lowest level in October 2024. For 2025, both lines rise into February, rise again to a peak in May, and fall in July 2024 before falling to its lowest level in October 2024. Two numbers lying along the lines show the infected colonies gained 0.05 frames of bees while non-infected colonies gained 0.54 frames of bees between May and July 2024. |
| And then again, with our frames of capped brood. This is still, you know, some of those larvae that are dying. They’re not making it to that capped brood season, or capped brood stage. But it seems strange that we actually had higher levels of growth for our not infected colonies. And that’s something that we’ll have to tease out a little bit more. Or no, that sorry, that is correct. There’s higher levels of not infected frames, about 1.08 frames of not infected or non-infected bees, and then 0.6 frames. That’s… That’s what we expected to see. | The next slide heading reads, Frames of Capped Brood by Infection Status. A dot and line graph shows an orange and grey line. The orange line represents the average frames of bees in colonies that ever showed EFB symptoms in any of the eight sampling points. The grey line represents the average frames of bees in colonies that never showed EFB symptoms in any of the eight sampling points. Both lines start low in February 2024, fall slightly in May 2024, rise to a peak in July 2024 before falling to its lowest level in October 2024. For 2025, both lines rise into February, rise again to a peak in May, and fall in July 2024 before falling to its lowest level in October 2024. Two numbers lying along the lines show the infected colonies gained 0.60 frames of bees while non-infected colonies gained 1.08 frames of bees between May and July 2024. |
| All right. I think I’ve got a couple more minutes and I’ll leave some time for questions. But the conclusion that that we can pull out from what we’ve done so far and what we’ve analyzed so far from the study. It doesn’t seem like there’s a lot of evidence that blueberry pollination increases EFB symptoms in Washington. And it’s a two-year study, we’re going to see much more data from Oregon State and the other universities come out. So far in Washington, we can’t really say that blueberry pollination increased. EFB symptom prevalence, but it does seem like there is some evidence that blueberry pollination is a little bit harsher on colonies in terms of amount of bees and brood than colonies that are being left at a holding yard. So if you move your colonies to blueberries. You really need to keep them fortified with additional syrup and pollen patties, which is something that we all need fed syrup and not pollen patties this year or those two years. So, there may be some deleterious effects rather than leaving them in their place. Oh, and I should also say, then EFB, of course, is harmful to your colonies and will reduce the number of bees and brood and can result in in early death of your colonies. | The next slide heading reads, Conclusion. Dr. Kuesel reads and elaborates on each bullet as he describes the conclusion. |
| So more to come again. We’re going to have about double the inspection data at Oregon State University. They were able to keep in touch with their beekeepers very, very closely, and were able to track more of those colonies throughout all eight inspection points, which was critical for this study. We’re going to get the vitellogenin analysis, so how much of that protein is present in the bees’ heads of the adult bees to see how well they’re being fed, how much EFB impacts that ability to store proteins in the head and then produce the brood food for larva. We’ll also see a laboratory analysis of bacterial presence, which is ongoing now and moving forward quite quickly, thanks to the folks at Oregon State University and then also out of Oregon State University, we’ll learn more about what bacterial strains of EFB are present in these larva at different periods of time and in the adults. We already know from Peter Fowler in 2025, that same study that there’s a lot of different strains of bacteria, of EFB bacteria, and they’re split up into typical versus atypical groups based on their genetics, and typically those typical ones are really not able to survive in oxygenated environments, and those atypical ones seem to be associated with a little more ability to grow in oxygenated environments. It seems like the atypical ones from their work has a little more virulence and co-infected colonies. So, colonies that have both typical and atypical strains they found have significantly higher rates of that clinical, meaning symptomatic disease levels. So, I’m really excited to see what data we can get for our bacterial strains and compare it to that group out of Michigan State and then eventually coming in probably 2027, or we’ll formulate or have evaluations of management techniques for EFB control. And then then in 2027, we’ll ultimately develop and effective EFB management practices that we can distribute to keep EFB it controlled and her colonies healthier. | The next slide heading reads, More to Come. Dr. Kuesel reads and elaborates on each bullet as he describes what is to come from the project in the future. |
| All right, that’s all I’ve got. I think we’ll move on into questions. | The next slide heading Questions? Support from the following: National Institute of Food and Agriculture. Specialty Crop Research Initiative. |
| Bri: Awesome. Thank you, Ryan. That was so interesting. We do have a couple questions already. How were the colonies in this study overwintered outside or in wintering sheds or indoor? Ryan: Great question. All of our colonies were wintered outdoors, so they experienced the harshest, most simple management tactic for colonies. Bri: Were the colonies treated for Varroa and with what and when? Ryan: Yep, we used a rotation of Varroa miticides. They were treated in almonds. I think year one it was treated with oxalic acid dribble. And then year two was definitely treated with thymol in those almonds. And we also treated for them in late spring, just before they went on into honey production and that typically was oxalic acid dribble. I think year one, it was, oxalic acid dribble in year two, that may have been switched. And then we treated them again in October, late October again with, I think, use the oxalic acid. That tends to be our go-to is the oxalic acid dribble. Bri: Okay, is there any relationship between PMS or parasitic mite syndrome and EFB? Are they related through poor nutrition? Is PMS an identifiable disease? Ryan: Good questions. I do not know of any links between PMS and EFB. They’re often confused for one another because the symptoms look so similar. We still think PMS is largely about the buildup of viral diseases in these colonies, and the weakening of the bees via those viruses, as opposed to EFB, which is the bacterial disease. But if you have a weakened colony from one or the other, from Varroa mite and its viruses, or European foulbrood, weak colonies are always more susceptible to other stressors and other diseases. So I don’t know of a direct link, but I would not be surprised if there would be one via that route. And then what was the you remember? What was the second part? Bri: Is PMS an identifiable disease? Ryan: Pms is… sort of a complex identifiable… explicitly, not really. It’s sort of an amalgamation of symptoms of this colony has a lot of different… a lot of mites and a lot of different viral diseases that are causing the colony collapse. So that’s kind of a catch all term for we have too many mites, and the colony is collapsing because of that. Bri: What type of smell is EFB typically associated with, if you can describe it? Ryan: Yeah, to me it smells like sour urine. Sort of a sickly sweet putrid, sort of sour urine odor. An American foulbrood is really dead fish to me. Bri: What statistical analysis was done on the data? Ryan: Yeah, good question. we’re going to finalize that analysis, but we’re going to end up doing. linear models on them that can capture both the beekeeper, the random effects of beekeeper, location, all of those random effects in addition to it, before we publish this data and finalize it. Bri: Are there any data sets about weather conditions during the peak infection periods? Ryan: Hmm. we did not capture that. That is something we could go back and look at a course level. I’m looking at past weather in the in each area. In my knowledge of the literature, I don’t know of any great studies that have compiled that. But I wouldn’t be surprised to find some. Bri: Okay, this is the last one so far. If anyone else has any questions, go ahead and start typing them in. So the last one we have here is, of all the hives that were dead outs, what percent do you think is attributed directly or indirectly to EFB? Ryan: Good question. I slide back. Actually, I couldn’t give a little bit better answer there. So we had about 92 and 96, we had about 188 colonies that we were able to survey for all 8 time periods. Of that, it seems like about 60 of them survived. And here I would guess it’s probably 15 over 60, so maybe, or no, it would be 15 over 60. It would be 15 over 188 minus 60. So maybe 11%, I’d say about 11, 11, 12%. Bri: Very interesting. okay, we got one more. do you think migrating the hives to the almond orchards increases the sharing of disease over a larger area, i.e. Hives coming from many different locations? Ryan: Yes, I would say yes, it’s quite likely. If you have robbing behavior, those bees might be entering colonies and pulling out infected bacteria or bacterial infected bee bred and nectar and honey. So I think that it could increase that risk. And that is one of the major risks of moving all of our eggs into one basket each year in almond pollination. Bri: After pollination in blueberries where the hives fed and managed or just left to recover on their own? Ryan: Yep. They we never did protein patties. But we did feed sugar syrup regularly. So we were monitoring the weight of those colonies and giving them sugar syrup. They would all receive sugar syrup if it seemed like some of them needed it. They were given that that syrup, but not maybe some of the pollen supplements that maybe they needed. Bri: Do you know of any supplements that help strengthen the larval gut? Ryan: That’s a good question. There’s a lot in the works. I know. I don’t know of any that are proven to work at this point. I think there’s a couple on the market, but as far as experimentally provable supplements. I don’t know of any, but not to say that there aren’t any. Bri: Okay. Awesome. Well, thank you so much, Ryan. It doesn’t look like we have any more questions. If you think of any questions later, you’re welcome to email Ryan. It’s ryan.kuesel@wsu.edu. I will also send a follow-up email, with the YouTube link once it’s posted, and I can copy Ryan in there, so you’ll have his email directly. Thank you all so much for attending this first webinar. As a reminder, before you close your browser, you’ll be prompted for that short five-question education and outreach impact survey. Again, this is the first of four webinars this year, so tune into our other ones coming up. Our next one is in March. and again, this is recorded, and they will be posted on our YouTube channel, Share it with your friends, and rewatch it as you please. Thank you so much again for attending, and I’m going to end the webinar now. Ryan: Thank you | View of Ryan and Bri alternate as each person speaks. |