Dr. Steve Pernal: Varroa Mite Research (343)

343 - Dr. Steve Pernal: Varroa Mite Research

Vicki Atkinson: Hello, this is Vicki Atkinson from Duncannon, Pennsylvania. Top bar beekeeper there. I want to welcome you to Beekeeping Today podcast. Thank you so much.

[music]

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

Becky Masterman: I'm Becky Masterman.

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Jeff: Hey, a quick shout out to Betterbee and all of our sponsors whose support allows us to bring you this podcast each week without resorting to a fee-based subscription. We don't want that, and we know you don't either. Be sure to check out all of our content on the website. There, you can read up on all of our guests, read our blog on the various aspects and observations about beekeeping, search for, download, and listen to over 300 past episodes, read episodes, transcripts, leave comments and feedback on each episode, and check on podcast specials from our sponsors. You can find it all at www.beekeepingtoday.com. Thank you, Vicki Atkinson, for that wonderful opening from the floor of the North American Honey Bee Expo. It's fun working through all those. Remember everybody?

Becky: I loved talking to Vicki, and she had so much enthusiasm for top bar hives, and she wanted us to talk more about them on the podcast. Then do you remember when we learned that she manages over 50 top bar hives? [laughs]

Jeff: I know.

Becky: She's an expert. [laughs]

Jeff: Yes. Wait, what?

[laughter]

Jeff: Vicki, thank you for that great opening. It's the end of July. We are pulling honey.

Becky: I do my honey in batches just because I need to, but that literally means that-

[laughter]

Becky: -I'm now getting two different flavors, and my bees will keep going for a little while longer. My arms are stronger and my back is really thanking me for the workouts. How about you? Are you extracting? You extract it once, right?

Jeff: Yes, I do. This year it's going to be a little disjointed because I'm in that home transition thing. I don't have my honey house anymore, so I'm not quite sure how I'll extract it, whether it be at my buddy Paul's place or I'll take it to somebody who does some custom extracting.

Becky: I'm going to give you a tip, Jeff. Don't do it in the bee yard.

[laughter]

Jeff: Oh, so noted. I won't.

Becky: I know you knew that.

Jeff: Or the doors open.

Becky: That's a robbing situation.

Jeff: How do you pull your honey? Do you use fume boards, escape boards, bee blowers?

Becky: I used fume boards, and I have now added a fume board this year, so I have a total of three. Don't get jealous. It's a big operation.

Jeff: [laughs]

Becky: I use Fischer's Bee-Quick, and that's always worked really well for me. My whole operation smells like marzipan because of the product, which is-- it's not bad, but it works really well for me. This isn't a commercial, but it works really well for me, and I don't mind the smell. It's just a process where literally I go to a yard, pull the honey, take it home, extract it, and then I go to the next yard the next day with the extracted supers, pull that honey, put the extracted supers back on the colonies so that it helps me where I don't need inventory for as much honey as each colony is going to produce every year.

Jeff: That's really good and you don't have to worry about the storage. My year's going to be a mess. I'm not quite figured it out yet. More on that in future episodes. Today's guest is Steve Pernal. We're going to be talking to him about varroa mites. I'm looking forward to it.

Becky: I can't wait to hear what Steve has to tell us about his operation-- not operation, but the government operation up in Canada.

Jeff: We'll be talking to Steve right after this word from our sponsors.

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Jeff: Hey, everybody, welcome back. Sitting around this great big virtual Beekeeping Today podcast table, we are excited to have Steve Pernal from Alberta, Beaverlodge, Alberta. Dr. Steve, how are you doing? Thank you for joining us.

Dr. Steve Pernal: I'm doing fine. Very happy to join you today.

Becky: Steve, it's quite an honor. Are you the highest-ranking beekeeping scientist in Canada?

Steve: I guess-

Becky: [laughs]

Steve: -it depends how it ranks. I work for our federal government, so the equivalent to USDA in Canada, which is Agriculture and Agri-Food Canada. Yes, I do lead our national honeybee research program federally. I have a great number of counterparts at Canadian universities, but we've got a small research unit in Northern Alberta in a little place called Beaverlodge, and it's been here for a great number of years. There's a lot of history behind being located here up in Northern Alberta. Historically, this has been a huge honey producing region, and we've retained a couple of research positions up here dedicated for the beekeeping industry.

I think there's a lot of other people in Canada that do great work, so, I don't know about most highly ranked.

[laughter]

Jeff: How far north in Alberta are you? We should have you back on our how to winter in northern climates.

Steve: Yes, we do that. I'm trying to remember what parallel we're on. I think we're almost on the 56th parallel here, 55, 56. There's a lot of Canada further north, but we're located in the peace region. This is a region of northern Alberta and northeastern British Columbia, which is a large agricultural region. If you looked at this latitude in the other prairie provinces in Canada, if you looked at Saskatchewan or Manitoba, there'd be far less agriculture. This is like a big island of agriculture in this northern part of Canada. It's expanded over time.

Because of our long days here in the summertime and the available forage, it's always been pretty good for beekeeping. We've got some very big honey crops and high productivity per hive.

Jeff: Why don't you tell our listeners a little bit about your background, how you got interested in bees, and why you're the-

Becky: [laughs]

Jeff: -top bee wrangler there now?

Steve: I ask that myself sometimes, how did I get here?

[laughter]

Steve: I started off, went to university. I was the one of my siblings in my family that did all the high school science fair projects, so maybe I was predestined to go into a geeky research career. My father was a university professor in Brandon, Manitoba, but he was not a scientist. He studied Eastern European history, but I liked the sciences and did an undergraduate degree in Brandon and went to the University of Manitoba for both my master's and PhD.

My master's was in entomology and in crop pest entomology. Then I got into bees, honeybee research in my PhD. That was with Dr. Rob Currie. Rob was a brand new faculty member and I was his first graduate student. I think through my exposure to entomology, I was quite interested in insects going through, was interested in social insects, and there was a great opportunity to study with a new faculty member who happened to be a bee specialist. That's how I really got into bees. I started beekeeping actually in my PhD. That's where I first really started getting my hands dirty with bees. Rob's recently retired, so my PhD mentor's retired. Anyways, that's how I got into it.

Jeff: In all your other duties at what many of our listeners may understand as the USDA but the equivalent in Canada, you've done a lot of different research on honey bees, and one of the big things that you've been working on is the varroa. Can you tell us a little bit about your research?

Steve: Yes. I've done a lot of different things over the years, but the entire time I've been working with bees, varroa has been a problem. I'm probably telling you something all your listeners know, we don't really have good things to control it anymore. A lot of the really potent miticides that have been developed over the years, mites have fairly rapidly evolved resistance to. You could see that happening in Europe for years and years before North America. Then similar things happened in North America. Now, our last sort of silver bullet with amitraz is really becoming ineffective. That's true in the US and certainly true in Canada. We've done a lot of resistance testing in the last few years.

We do have products that are available to beekeepers in North America. Primarily, a lot of the organic acids, like oxalic acid and formic acid, and they do kill mites, but they tend to be harder to use. They require more repeated applications. They're more temperature dependent. Things like formic acid can kill queens, and certainly, they're more hazardous to beekeepers. In one way, thankfully, we have something available to kill mites on bees, albeit it's more complicated and more labor-intensive, but there's a really dire need worldwide to find other varroa controls. I think, again, most of your listeners will know that. That's not new news.

What's interesting is even though I have trialled products in Canada before, we have a registration process similar to the US. As a government lab, we have some interest in trying to supply data for public good and help register products in Canada that either have been registered in the US or not registered in the US. The current opportunity I have is a bit unique in that I'm evaluating an entirely novel compound. This is something that's never been used on mites before. It's never been used on anything before.

Typically, all the stuff we kill mites with has had other uses in agriculture. It's been co-opted to kill varroa. This particular compound we're using was discovered by a good collaborator of mine, that's Dr. Erika Plettner at Simon Fraser University, just outside of Vancouver. It's funny how connections work. I did a postdoctoral fellowship at Simon Fraser quite a few years back, at '98 to 2001, and Erika was, I believe, just finishing her PhD at that time, but we briefly overlapped.

I worked in Mark Winston's lab, and Mark had a big history of discovering the components of queen mandibular pheromone. I was looking at similar substances for mites. We were trying to see if there was anything about the semiochemistry of mites we could use to exploit and kill them. Erika had come and worked in Keith Slessor's lab, who was the chemist behind a lot of that pheromone work. We briefly overlapped, but she ended up getting a faculty position at Simon Fraser University. She still kept in contact with me, and at one point she said, "Well, Steve, I've got this compound. We think it's pretty promising to kill mites." She was gently suggesting I should try it.

Initially, I didn't want to because a lot of people come to me and say, "We've got this great thing for killing mites."

[laughter]

Steve: A lot of beekeepers tell me that, or they look up on the internet and say, "Hey, I found this thing," so I have to be a bit judicious in what I spend my time on. Nevertheless, certainly when I spent a little more time looking at it, Erika had some very promising data. When you start working with compounds like that, you start small. Working with bee colonies is time-intensive and also expensive. You do little tests called bioassays or lab tests, and you expose bees or mites on bees or mites themselves to doses of these compounds, and you see whether, in fact, they have an effect on that mite.

Erika's background, a lot of her previous work, had been with what we call phytophagous insects or crop pests that feed on plants and kill them. She was trying what we call these libraries of compounds. She's a brilliant chemist, these libraries of compounds with little structural changes to them to see if they had different activities against insect pests like cabbage loopers, this is a moth. Because we both had this common history of looking at semiochemicals from working in labs, she has still maintained quite an interest in bees and decided to trial it against varroa.

Some of these compounds in these libraries had activities against varroa. Then by doing quite a number of tests, she narrowed down these groups of compounds that had activity. When I got involved, we did some bioassays in my lab. She continued to do hers, and collectively, but mainly, certainly, Erika, narrowed down the most active compound to something we call 3C. Why is it called 3C? Because it's easy to say.

[laughter]

Steve: That's just what we call a library name, the name of this compound, and it's patented by Erika and Simon Fraser University. It's called 1-allyloxy-4-propoxybenzene. That's the-

Becky: Oh, no. [laughs]

Steve: -chemical name, but it's a mouthful, and I'm used to saying it. The library name technically is 3C (3,6) and we call it 3C. I'll just call it 3C-

Becky: Thank you.

Steve: -because it's easier to say.

Jeff: Thank you.

Steve: That's what we call it. I got involved with 3C in 2019, and I did a field trial in the fall. We applied the compound using little wooden sticks, almost like wooden rulers. We put them in the colony either on top of the top bars or in between the frames. Erika formulated these wooden sticks for us, and we put them into colonies. That first fall, we had really pretty impressive mite fall in these colonies. Then I got really interested. We have continued to work together over these last few years to vary the application, how the compound is put on these ticks, or Erika has. Also my part has been really varying dose and colonies, and also timing in terms of when we apply this compound at a certain time of year. We've looked at efficacy, so how it can actually kill the mites.

I like to say I practice a lot of anti-beekeeping. I do things to our bee colonies here at our little research farm which beekeepers should not do. Sometimes we give them diseases and treat them. In terms of treating mites, we farm mites that infect colonies and use a bit of science and witchcraft to try and get them infected at a certain level. You don't want them to have too many mites because then it's unrealistic, and not too few because then you don't see effects. You homogenize them and get them all the same size as the same mite loading either in fall or spring, typically, and then apply that treatment.

We've put that compound on for either four-week periods or six-week periods. We now use a six-week period, and then we look at various doses that give us good efficacy. That involves counting an awful lot of mites that fall onto sticky boards at the bottoms of hives so you can see how well those mites die. After we apply that experimental compound for six weeks, we'll follow up with a finishing treatment, or a cleanup treatment, we call it. We used to use amitraz because we didn't really have resistance, and now we do, so we have to use combinations of other things. We clean out as best we can the rest of the mites in the colony not killed by the treatment to calculate the relative efficacy of the compound.

I've been doing a lot of efficacy experiments, and also more recently, concurrently looking at effects on the bees. When we put this into a hive, is it killing the bees, or is it doing it subtly? Are the populations of the colonies lower? Do we get brood dying? We're doing some of those latter experiments more recently and trying to build a bit of a data set.

Jeff: We did talk to Erika in 2024 April, so if our listeners, after you finish listening to this episode, want to hear more about Erika's work and the other area she's working with, check out April 8th, 2024, our discussion with Dr. Erika Plettner.

Steve: Maybe her version's completely different, I don't know.

Becky: It tracked. Don't worry, Steve, we've got the--

Steve: No, it's perfect.

Becky: This is very exciting to have a continuation of what we learned from Erika. I only have about 12 follow-up questions, so whenever you want to let me go. [laughs]

Steve: Just very globally, both Erika and I, and I also point out other people that have used this compound. That would include Steve Cook with the USDA that's trialed it. More recently, Véto-pharma in Europe has. Erika, with Simon Fraser University, formed a partnership with Véto-pharma. Erika is at the helm of deciding how to commercialize this product. She and Simon Fraser formed that agreement with Véto-pharma to look at things like applicator developments, so something that would turn into what the final applicator will be, and also to be a participant in identifying what gaps we have in the regulatory process. They've come on as the third player in this process, and they're bringing certain expertise that neither I nor Erika have.

What's been interesting for me is sometimes you think you have a great thing going, and somebody else in some other part of the world uses it and goes, "You know what? This really doesn't work." On the whole, the participants that have used the product generally have found that it has mite-killing efficacy. It does vary, depending on environmental conditions and brood cycles, but-- I'm pretty satisfied now. We have something that does kill mites, I think, in our conditions, which is a very temperate climate with a really well-defined winter.

It tends to work fairly well. In other parts of the world where the brooding period is longer, we may have to devise other treatment regimens where you just need control longer in the season.

So far, I'm fairly convinced we're onto something that'll eventually be useful for beekeepers, but there's still quite a bit to go between now and when we have a registered product. That's mainly to do with the fact this has had no other use in agriculture before. We would have to put together a technical package for the active ingredient, and Erika certainly has started towards that. Then Erika and I and partners will have to develop the other parts of the package, which would include things like its mite-killing efficacy, but also, very critically, its safety to bees and its safety to humans. Develop things like residue detection techniques to see how much this compound is left in the honey or in the wax of bee colonies. We're working with other partners to do that right now.

Becky: I know that initially she did say that there was some residue in the comb. Is this the treatment that would most likely be not during honey production, used during honey production but have to be off the colony prior to that supers going on?

Steve: I don't want to be too definitive about use patterns yet, but I would venture to say we would be safest to have more of a traditional treatment window, such as the fall and spring. The compound is lipophilic. It ends up partitioning and getting into the wax, primarily more so than honey. Again, Erika is the super chemistry expert, so she can go on about this, but I know she's demonstrated, for example, that the compound offgases from combs. Over the winter there's a very large reduction of the concentrations you might find in the comb if you treat it in the fall versus the spring, so it's not locked in there forever, but you can find the compound in honey and wax, which is true of almost any other miticide we use in a beehive. We're just going to have to really come up with the best use patterns. I would venture to say at this point, probably not during the flow.

Becky: You got to the point where you're using the treatment on a full-sized colony. Is that a two Langstroth-deep colony?

Steve: Yes, our testing so far has been on singles. Part of that's just been practicality. I think eventually we'll have to use-- and it's both for Erika and myself. Other partners may have used this on doubles, I'd have to go and check, but we've been looking at our dosing on a per-box basis. We've run everything from 4 grams to 10 grams of this compound in a box. I think we're finding this sweet spot. 10 grams, I think, is a little too much. We may be seeing some effects on these, some subtle effects. Probably 8 grams per box is what we're going to continue evaluating as the preferred dose. We're again going to have to work out techniques for different colony sizes. Of course I'm sure we'll continue to take on partners to test what may be the approved applicator device in different parts of the world.

Jeff: How is it applied? You have different applicators that are being developed, but is it through contact with the chemical, the varroa?

Steve: Yes, some of that's known, and some of it's not known. We would characterize the compound as having low volatility. It does evaporate, but it evaporates slowly. It'll evaporate in the hive environment, evaporate over several weeks. I would venture to say you are getting some volatilization of that compound in the hive environment, and we do have data to support that. You can actually trap it and monitor it in the air of the colony, and some of it is spread by direct contact with the strip and bees. I think it's getting moved by those two modalities primarily.

Becky: I think it's exciting that Véto-pharma is a partner because that means that it's not going to just be one country. It'll be hopefully multiple countries that they'll be able to release it in once it gets approved or work on that simultaneously.

Steve: That's absolutely true. It's one thing working with an experimental compound in a university lab or in a government lab, and it's quite another thing to have a registered compound and be able to manufacture it. Obviously, some partner is going to have to come on board with this process. It wasn't in-house developed at a multinational rate. I think the initial interactions we've had with Véto-pharma have been very good and very supportive. Of course, they've got a huge vested interest as well, but you don't really see it as a unique partnership between primarily SFU and Véto-pharma. I think what your local government lab brings to it is a public good perspective. I think we have a very good perspective on how beekeepers use products and what some of the limitations are and really using it in real-world testing.

I think we're all bringing something to the table, and I'm potentially excited to be part of this where we are now, as we've really shown proof of concept to a large degree, but there's certainly a burden to produce data that's going to be used for registration. Both Erika and I are in the midst of applying for lots of grants, which will come into effect in 2026. Those grants we anticipate will be used to support more of the data that'll be used to support registration with what'll look like the final. We hope it will look like the final applicator.

Becky: It's a journey, isn't it, to get from product idea to product testing to legal product registration and on the market? It's years and years.

Steve: Yes, absolutely. Number one question I get from beekeepers is, when is it available? I don't always have a good answer for them. I can just tell them where we are on this journey. I feel for them. I get it. We bee keep, too, and we have the same issue. We're doing our best. Again, we're forming partnerships that'll try and actually make this happen and perhaps make it happen a little more quickly than if we try to do it ourselves.

Jeff: Hey, this is a good opportunity to take a quick break and hear from our sponsors. We've been talking with Steve Pernal of Agriculture and Agri-Food Canada. We'll be right back.

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Becky: Welcome back, everybody. Steve, I just wanted to follow up. You mentioned that you had to get good at varroa population dynamics in order to do research and have an estimated population for the actual experiments. Do you feel like you have a much better understanding now of varroa population dynamics that you can share with us? You're trying to make sure they're not too low or too high for an experiment, but how hard is that to get to?

Steve: It's super hard. It really depends on starting populations of mites, amounts of brood, how those colonies have been started. I can tell you for some of our other projects that we've actually tried to really tightly control varroa dynamics in colonies, what we've actually done is we've started with broodless package units, and we've actually seeded the colonies with individual mite loads. We've estimated how many mother mites we need to start a population.

We had mentioned Renata before previously in the Minnesota lab, when she was a postdoc with me. She was involved in a project, and I remember she worked with me, and she seeded these individual package-style units so that at the end of the summer we'd have certain population loads and we can do certain population evaluations. You have to get to that level of detail. You'd have to actually control number of mites, numbers of bees, and standardize the size of the units so that the population dynamics among these colonies as they grew were really, really similar. From a really geeky research perspective, that's how you'd really standardize the growth of mites in those colonies.

If we're doing our efficacy testing, we can cut ourselves a little slack because we're doing something that looks real-world. There's going to be some variability in those mite numbers, but we just have to monitor quite a lot and try and estimate mite population growth. I guess there's two scenarios. One is, may come out in the spring, we really look at our colonies and look at mite loads and hopefully have a group that are in the ballpark of exceeding what might be an economic injury level. We would say here, if we can detect the mite in the springtime, it needs typically treatment. We don't want ones that have huge mite loads because that's not necessarily a realistic test.

Then for the fall, it would be either actively at managing mite populations and colonies with treatments or starting units that get small and actively monitoring mite populations and sometimes manipulating brooding them to try and achieve colonies that are similar in size with similar mite loads. That's quite tricky. You can do the best you can by maybe estimating mite population growth and manipulating those colonies, but inevitably, you end up with variability.

What happens is we end up with these groups of colonies. We monitor them, and then we sometimes have to take out a number because they just have too many mites, or they have non-detectable mites, and then stratify the treatments with ranges of populations of mites within the treatment group, so it's tricky. I don't think I have any magic knowledge. I think it's just a lot of active management.

Becky: I think, actually, that should make us feel pretty good because it's really tough to predict numbers. You can do a test and see what your levels are, but we all have those colonies that have increased levels, and we don't know how it happened. I think you made a bunch of beekeepers feel good. I have a quick follow-up, though. Canada's always had, I think, really good economic threshold for treatment of varroa. What are your treatment levels right now, your threshold levels, or your recommendations to beekeepers in Canada?

Steve: We used to traditionally say always 1% in the spring, been pretty consistent, and I think a 3% level in the fall. It's been interesting. I know Dr. Nuria Morfin, who recently was heading up the tech transfer team in British Columbia and has just recently this year moved to my former mentor's position at the University of Manitoba. She revised a treatment threshold recommendation for the fall down to 1%. I would say, in effect, what most of our commercial beekeepers are using is pretty much detection in the spring and a 1% level in the fall to prevent what they feel is economic damage or loss over the winter. I believe our thresholds have come down, and I also believe that's related to the virulence of viruses that mites are actually transmitting.

Becky: You said detection in the spring. That means if you do an alcohol wash and you see varroa, then management is needed?

Steve: Yes. Formally, that level would've been 1%, but essentially, detection would mean if you're detecting mites in that colony, we're treating for it. I've been fairly impressed by what I see with a lot of our commercial beekeepers. They've been pretty vigilant despite the labor now required to treat mites. Levels have been surprisingly, I think, well managed, but it doesn't change the fact we still have lots of years with huge mortality, just as you see in the US. It's a pretty complex picture, but keeping on-- inevitably, when we have train wrecks, they're usually related to high mite levels.

Becky: Minnesota's really close to Canada, so I'm taking those thresholds. Thank you.

[laughter]

Jeff: Besides rural, you do a lot of other work in your role, and one of those that stands out is your Genome Canada project.

Steve: Yes. Genome Canada is a granting agency. It's a federal granting agency, and they support, as the name implies, genomic proteomic projects, omic projects. When I started my career, I never would've dreamed that I would be on a genomic project because I'm not a genetics person, per se. I've learned a lot over the years. Science is a lot about networking, and I think science is much more multidisciplinary than it ever used to be, which is mind-blowing because I get to work with people that are way smarter than me and have way different disciplines.

I know, looking at genomic projects, I first connected with Dr. Leonard Foster at the University of British Columbia. Again, we share a little common history together. We passed through, again, Winston's lab but at much different times, but he came highly recommended to me. He was a new faculty member at UBC, and I had been working here for a little while. He runs a core proteomic facility at the University of British Columbia. He does lots of crazy and great things, but he's still maintained this interest in bees.

In terms of the omics projects, I started working with him initially, and we started actually looking at things like markers, actually proteomic markers, which are unique for determining which bees might be more hygienic than others. That was the basis of our older projects, and that's what I found super interesting. We worked together and common interests, different expertise, but we, I think, put together some pretty good projects.

As time has gone on, there's been many more partners, particularly Amro Zayed at York University that is a honeybee genomics expert. I've been part of a team. I haven't led or co-led these past couple of projects but have been part of a very large team. I would venture in Canada, they've been the largest bee projects done on this side of the border. This last one will be called BeeCSI, and people ask me why, and I say, because you have to have a catchy name for a big project if you're going to get a grant.

Jeff: [laughs] That's B-E-E-C-S-I, right?

Steve: Yes. B-E-E-C-S-I. That's right. That project was co-led by Amro and also Leonard, and I was one of several collaborators on that project, but we had labs working at UBC here in Beaverlodge and in Lethbridge, the University of Manitoba, University of Guelph, New York University in Louisville. Hopefully, I didn't leave anybody out, but I believe those are the main labs in Canada, and all of them are either core bee labs or certainly have an interest in bees and bring different specialties to that.

The last focus of this last series of grants really was looking at whether we could develop markers of stress in bees or detect markers of stress in bees looking at genomic signatures, expression profiles, or through proteomics to better predict or real-time analyze why colonies might be dying. That takes a lot of coordinated work. Working on a big project, a big downfall can be working with a lot of people. Fortunately, most of us get along, but the coordination is a huge, huge part of that. We, collectively as a group, designed protocols and had similar experiments going on at all these different sites in Canada.

For example, I was just looking at one recent paper the group had published, and I just noted there was 114 different field sites and almost 500 different colonies. With a lot of the experimentation for this last project, what we tried to do is follow bee colonies in different crop pollination systems. In Canada, we pollinate crops not nearly as much as the US. Big crops for us would be hybrid canola seeds. All that yellow canola that bees love is purchased every year by farmers. That's hybrid seed. It has to be bred every year.

We primarily use honeybees to do that crossing, and also leafcutter bees. In Canada, that's a huge multi-billion-dollar crop. Contribution of honeybees and, to a lesser extent, leafcutter bees is huge for that. We also have bees that pollinate things that you're familiar with, blueberries, highbush and lowbush blueberries, apples, cranberries, some vegetable crops, et cetera. What we did is we put bees in these different crop systems, and we put them in holding yards before they move onto the crop system. Then we moved them in mid-bloom, and they did their pollination thing, and then we followed them after they left. They were moved out. We had these three time points.

The beauty of some of these projects, even though they're very omic-heavy, is we also have a lot of phenotypical data. Sure, you can examine the omics, the genomics, the proteomics, but you also collect a lot of data on what these bees are doing in these crops. Some of that other data could be pesticide exposure, it could be population size, it could be foraging activity. You build this huge because you have this multi-site experiment, this huge database of all this phenotypic data, as we call it, that couples whatever genotypic data's mined out of the DNA of these bees or looking at maybe their proteomic signatures as well.

Some of the early papers from this big project, and it takes a long time to bring this data together, really has brought out some interesting stuff. One recent paper is on stressor networks. Sarah French was the lead author on this project. She came out of Amro Zayed's lab, and a lot of us contributed to it because we contributed data from all of our sites individually. Somebody like Sarah and many others has analyzed this data and pulled some sense out of what we're seeing. At a level of what we call stressor networks, which are things like, "Hey, what do these bees have in their hives that are stressors?" They're pesticides, typically, or their diseases.

When we look at them over time before they get moved into a crop like canola or apples or blueberries, et cetera, and we look at them on the crop and we follow the crop, we can see the total number of stressors they accumulate and interactions. There's a very detailed analysis of this, but there's some real, tangible take homes from some of this work. One of them is that honey bees are really exposed to a lot of stressors all the time. It's not like at this time, one time point wherein there's a little panacea of these, I don't know, of this pasture. They have no stress. They're still exposed to things like diseases. There still might be pesticide exposure, remember this, in high miticides that we use.

We move on to the crop, and we typically see things that we would expect, like exposure to pesticides particular to the crop system. Then they tend to retain those stressors as they're moved out because they've collected that nectar, they've collected the pollen, and it stays in those hives. One figure I remember is on average in this study and all these little experiments we did across the country, when you moved a bee colony into this crop they were pollinating, they were exposed to an average of 23 stressors, which had 307 interactions. You may have to get somebody like Sarah French to explain all those interactions, but what it means to me is, they're exposed to a lot of stuff and it stays with them.

In some of our very highly intensive crop pollination systems, and I'm sure in the US you can relate to this, they get exposed to a lot of stuff that stays in those hives and act as stressors and can affect colony performance. Also when you look at the breadth of foraging in some of these crops, you find that bees that stay in those crop systems and don't fly as far tend to get exposed to certain crop specific pesticides.

If we look in other landscapes where bees have the ability to collect pollen more broadly in these landscapes, when they collect pollen more broadly, which tend to be less agricultural and more urban, they're not free of stressors, but their stressors are more disease related. In those colonies, we have greater exposure to a greater number of viruses, for example, some pesticides that are more common use, and also bacterial diseases. In terms of the stressors bees are exposed to, it goes without saying it's complicated. They're exposed to a lot of stressors all the time. In terms of our ability to predict when colonies might die, it's very linked to region and exposure, and there's this dichotomy of pesticide exposure and also disease exposure.

It's a hard thing to put into a nutshell, but it really is eye-opening in terms of saying, when you look at this crop system and you look at the stressors to bees, it can be quite different than other crop systems. in Canada, for example, the one crop we put bees into that hide the highest numbers of stressors were cranberries, followed by a crop like blueberries, and then intermediate might be canola. Crop systems with lower stressors but still detectable stressors would be things like apples or soybeans. It really is contextually dependent on region and crop.

Anyways, that might be a bit of an abstract description of things, but we're trying to say is, what's really going on in colonies and why can't we predict when a colony dies? You think we should be able to do this by now. We can because it's very complicated and what we call the stressors are the things that actually affect productivity and health of bees are very contextually dependent.

Becky: I really used to like the narrative of the bees go to work in pollination and then you bring them, for example, back to Minnesota and you put them out for honey production. I don't want to say all the stress, but a lot of their stress is alleviated. You're telling me that there's a good chance that it's not, in the sense of your data show that when they're moved out of the pollination, they retained those stressors.

Steve: Yes. At least at the time scale we detected them because that pollen and nectar is still in the hive. A lot of the residues we looked at in terms of what we call risk quotients of the pesticides, individually for a lot of these pesticides, they're low. They're not going to immediately kill bees, but if you added up dietary exposure in certain crop systems, so there's a lot of little amounts of pesticides and bees eat a lot of that and store a lot of it, cumulatively, there can be a potential sub-lethal effect in those colonies.

I think it's true that a lot of these colonies going into intense pollination systems or there's a lot of pesticide use have that hangover effect that stays in the colonies for a while. Hopefully they can be moved to an environment which is less pesticide intensive but also less bee intensive. We looked at these colonies that were in these somewhat urban landscapes or more urban landscapes. Think of the lower mainland of BC where some of this work was done as well, and then maybe technically out of ag regions. I don't know if you've heard the term poisoned oasis. Maybe in an urban area, you set up this wonderful bee garden. Who goes there? All the bees in the concrete jungle glom on this garden and they're sharing things like diseases and you have disease spillover. I feel like Dr. Doom and Gloom here, but just different things are happening in different landscapes.

Keeping bees healthy involves minimizing pesticide exposure and having enough foraging space for bees and monitoring diseases and pests. There's a reason why we have continued losses in bees, and it's because a lot of the answers are very complicated and they're very contextual, depending on where those bees are going and what they're doing.

Becky: I really wonder if you have a tool now where you can study management. If you study the stressors when they're in the different environments and then once they get to the post-pollination environment where there's a heavy nectar flow and, for example, they dry out a box of new comb. You split the colony, put on just foundation, which I think a lot of people are resistant to doing the whole box if it's a commercial operation. You do a whole box of new comb and you see, hey, did that nice clean comb alleviate any of that? Anyway, you have a cool tool, but it's a big deal, right?

Steve: Thanks. Truthfully, we have a lot of data to mine, so we've got some pretty bright young people writing some pretty incredible papers. I think there's more to come off these studies. As I said, science is very interdisciplinary and we're learning things I had no idea we could really look into before. I think that's pretty cool.

Jeff: Does your department have a website?

Steve: I have a governmental website, which is probably a lot less jazzy than the one you have.

[laughter]

Steve: You can google me and I come up somewhere. Working within the government, we have to put our papers into a database and our outputs and our talks. They eventually get populated on the website. They'll roll up to my own governmental little webpage there, but people can reach out to me individually as well. That's certainly fine.

Becky: I think we have so much more that we'd like to talk to you about, but maybe after you winter your bees this next fall or early winter, maybe you could come back and join us and share more.

Steve: Yes, absolutely. I've had lots of great people working for me. For instance, Courtney MacInnis has looked at a new internal parasite of honeybees called Lotmaria passim. We could talk about that. We're continuing to do other work, so I'd be certainly happy to talk to you anytime.

Jeff: I look forward to having you back on the podcast, and I do look forward to meeting you in person at the Washington State Beekeepers Association meeting in October.

Steve: All right. Always better face to face, but it's still nice to see you virtually.

[music]

Jeff: Very good. Steve, it's been our pleasure having you here today. Thank you for joining us.

Steve: My pleasure.

Becky: Thanks, Steve. Jeff, that was so nice to talk to Steve and also get an update on all that great work Erika told us about, Erika Plettner.

Jeff: When he mentioned Erika, all of her conversation came back and it was like, "Wow,"-

Becky: Wow.

Jeff: -"this is really cool."

Becky: Me too. [laughs]

Jeff: I really encourage our listeners to go back to that April 8th, 2024, episode with Erika to listen to her talk about very cool research that she is doing.

Becky: I just remember after talking to Erika, how happy I was that there was just another tool being developed for varroa. I'm sure I used that same phrase in that episode, but I was so excited about it. I just didn't know that's what Steve was working on, so to hear that it's progressed to the point where they're closer and closer to being able to apply to have it registered or actually they have to get it formulated for application, but they're closer and it's going forward. That's just great news today. I'll take it.

Jeff: That about wraps it up for this episode. Before we go, I want to encourage our listeners to follow us and rate us five stars on Apple Podcasts or wherever you download and stream the show. Even better, write a review and let other beekeepers looking for a new podcast know what you like. You can get there directly from our website by clicking on the Reviews tab along the top of any webpage. We want to thank Betterbee and our regular longtime sponsors, Global Patties, Strong Microbials, and Northern Bee Books for their generous support. Finally, and most importantly, we want to thank you, the Beekeeping Today podcast listener, for joining us on this show. Feel free to leave us questions and comments on our website. We'd love to hear from you. Thanks a lot, everybody.

[00:49:04] [END OF AUDIO]