Ping Yu: Hello everyone, welcome to the Blooms and Beyond podcast, a podcast that uncovers plant history, culture, and management through the lens of science. I'm your host, Ping. I have Dr. Alexandra Revynthi joining me today to talk about one of the most exciting topics for me and for her, thrips parvispinus.
Ping Yu: I got to know Dr. Alexandra Revynthi through a grant that we both are on. That's thrips parvispinus. So she works on the chemical and biological control side of things and I, of course, working on a horticultural perspective for the pest control. So I'm very excited to talk to her on this pest management.
Ping Yu: And I don't want to steal any more thunder from our speaker today. Without further ado, here is my conversation with Dr. Alexandra Revynthi. I hope you enjoy it. Hi, Alexandra. Welcome to the podcast. But first, let's start off with the introduction. Can you tell our audience a little bit about who you are and what you do? Alexandra Revynthi: Hello, everyone. Thank you very much for the invitation. I'm very happy to join you today.
Alexandra Revynthi: My name is Alexandra and I originally come from Greece. And I was born and raised there and I did my undergraduate studies. I'm an agronomist by training with a specialization in crop protection. And that's how my passion started for plants and entomology.
Ping Yu: Yeah, before this session recorded, I was asking her how to pronounce the name. But it was, for me, it's common because a lot of times I want to make sure that I don't spell it wrong. I got that too for a lot of people because I am not American. Fortunately, my last name is pretty simple. I guess you got that a lot from people.
Alexandra Revynthi: Right? Yes. Also the way that is spelled in English, because we have a different alphabet, so they are trying to correlate the right Greek character to the correct Latin character. So usually we wouldn't write my last name with a Y, but upsilon corresponds to a Y, so it makes the pronunciation very difficult for an English speaker.
Ping Yu: Yeah, before earlier today, I was Googling, I was doing my homework, and I come across with a Greek dish that's called revithia. Do you know the dish that I'm referring to right now? Alexandra Revynthi: Yeah, you're referring to chickpeas, which are called revithia.
Alexandra Revynthi: And indeed, originally my family comes from an island in the Cyclades, that is a small island in the western Cyclades that is called Serifos. And in this region, the name is very typical, and it actually signifies chickpeas. And it happens also that one of the traditional dishes of this region is oven-baked chickpeas. Ping Yu: Oh! The Greek dish...
Ping Yu: Greek dish does have some correlation in there.
Alexandra Revynthi: It has a link. It's just that my great grandpa didn't want to have this link, so he actually changed the spelling of the last name.
Ping Yu: Okay, gotcha.
Ping Yu: It has a link.
Ping Yu: Oh, that's so interesting. I was like, what is that? Because I can only find the word for that recipe or for that dish, but not your name. Okay, now it makes sense.
Ping Yu: So you mentioned you grew up in Greece, but do you grow up with plants? What first sparked your interest in plants or horticulture in general? Can you share your career path or your background?
Alexandra Revynthi: So I remember everything started when I was very young. I was visiting my grandma. We had Easter holidays. We were off from school and I was in her house and I was taking a walk and collecting flowers. And this triggered my interest for plants. I went to my mom and I told her, tell me who studies plants and who works with plants.
Alexandra Revynthi: And I told her, okay, this is what I'm going to be.
Alexandra Revynthi: She said, are you sure? I said, yes, this is what I want to be.
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Alexandra Revynthi: I was 11 at that time. And my mom was excited because it happened that she was working in a pest control company.
Alexandra Revynthi: So she was, although she is not an agronomist, she was familiar with the profession and the challenges that the profession has.
Alexandra Revynthi: So she guided me through to find my way towards agronomy. So this is how I started. And my parents always thought, she's 11, she's going to change her mind. It's too early, but I didn't. And I'm happy that I didn't. Because it was really a dream that came true when I entered the university and I...
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Alexandra Revynthi: I had the opportunity to study everything about plant protection. My initial plan was that I wanted to study ornamental plants and particularly landscape architecture. That was like the plan. But already in the first, second semester, I think it was, the first year, we had agricultural zoology
Alexandra Revynthi: as a course. And this is where I fell in love with the topic. I fell in love with mites, actually. So I had very good teachers and they introduced us to this topic and it was great. So I started shifting away from ornamentals. I ended up doing my thesis with direction to plant protection. I specialized in entomology and acarology. And I did my thesis on an invasive mite, the pest that we had in Greece at that time.
Alexandra Revynthi: So when I graduated, I wanted to continue in research and I wanted to do a PhD on mites. And my plan was to find the best acarologist in the world. And I was very lucky to learn that he was based in Europe. His name was Maurice Sabelis [VERIFY]. He has passed, unfortunately.
Alexandra Revynthi: So I tried to find a position and do a PhD at the University of Amsterdam. So I left Greece and I moved to Amsterdam and initially I started as a researcher. After a year I started my PhD on predatory mite behavior [VERIFY].
Alexandra Revynthi: But then the twist was that I also was lucky. So the plants that I was using for my study were actually roses. So I ended up combining both ornamentals and mites at the same time. So I was very happy that I could combine both interests in one topic.
Ping Yu: Yeah, and now you are. So basically, you worked at Amsterdam for a couple of years before you moved to the U.S., right? When did you move to the U.S.? Alexandra Revynthi: No, I did one year before my PhD in Amsterdam, just plain research. And then I did my PhD for four years [VERIFY]. And then I moved immediately to the U.S. So I came here as a postdoc.
Alexandra Revynthi: My first postdoc was in collaboration with the University of Florida and the USDA APHIS. I was based in USDA APHIS in the treatment lab in Miami in Coral Gables. And then my second postdoc was based in the Tropical Research and Education Center.
Alexandra Revynthi: with Dr. Mannion [VERIFY].
Alexandra Revynthi: And I was working with invasive pests of ornamentals like the hibiscus bud weevil [VERIFY].
Ping Yu: Can you give us like an overview of your research program at University of Florida right now?
Alexandra Revynthi: So currently I'm working at the Tropical Research and Education Center as an assistant professor for ornamental entomology and acarology. The main theme of the lab is developing integrated pest management programs for pests that plague the ornamental industry.
Alexandra Revynthi: But the program is actually divided into two main pillars.
Alexandra Revynthi: Again, ornamental entomology is the first one, and the second one is agricultural acarology,
Alexandra Revynthi: because there is still a big need for people that are specialized in mites.
Alexandra Revynthi: In the US, we don't have so many mite specialists as in other countries of the world.
Alexandra Revynthi: When it comes down to mites, we prioritize ornamental plants, but I might deviate slightly if we have a pressing mite issue in the region. But we always try to develop integrated pest management programs for these pests and considering their
Alexandra Revynthi: as well as the different management tools that we develop.
Ping Yu: Yeah, because I lived in Florida and I know Florida is a heaven for plants and pests.
Ping Yu: And especially for parvispinus, for thrips parvispinus, it is an invasive pest. It was...
Ping Yu: Apparently, Florida is the first official report of this invasive pest back in 2020. Can you give us a little bit of background of how you started to work with this pest?
Alexandra Revynthi: It's an interesting one. I don't even remember how I started working. I do remember I saw the pest alert.
Alexandra Revynthi: that was already published in 2020. And we started having our eyes open. It was not for people that work in our field in Florida. It's very common to have invasive pests all the time. At that time, when thrips parvispinus appeared, I had already been working on a weevil, invasive weevil, and an invasive snail. So when the thrips arrived, we were like, "Okay, here we go again."
Alexandra Revynthi: So we started just keeping our eyes open, making sure that we don't miss it. Because initially, that pest was found in a greenhouse. In Orange County, Florida. And as far as I know, we started seeing the pest. I think it was in late 2021.
Alexandra Revynthi: And I think the first official report, if I'm not mistaken, came in January 2022. This is when officially we recorded it being present in Homestead in nurseries. And of course, it triggered a lot of concern because the ornamental growers could see a lot of damage on the plants and they could see thrips. So they said, OK, I have thrips and then they would take action to manage thrips.
Ping Yu: because they thought it was one of the old thrips species that they were familiar with. Actually, the management practices that they were implementing would not work. Yeah. To make things worse, especially in Florida, because I think shortly after its official report with thrips parvispinus, the Florida growers had to...
Ping Yu: suffer from a regulation because this pest has become a quarantined pest, which means that they have to be 100% clean with this pest before they can ship out their plant materials. Otherwise, they're going to shut down their whole operation. So they're under huge pressure in that regard. But with you working a lot on mites and other pests,
Ping Yu: What is the biggest difference between working on mites and thrips? Alexandra Revynthi: Actually, thrips are the best insects to work with. I love mites because they are easy to work with. They are very small and researchers might feel intimidated by their size, but it's actually an excellent material to work with because their life cycle is short so they can reproduce fast.
Alexandra Revynthi: So you can obtain results fast because the reproduction is very fast. And thrips give you exactly the same opportunities. So when we got the thrips, I felt hopeful that we will find the solution. We will make it work because I had already experienced working with thrips.
Alexandra Revynthi: I had worked with thrips at the University of Amsterdam, and I knew that they reproduced fast. So we were in a position to develop management tools much faster than if we were working with a pest that has a long life cycle.
Ping Yu: Yeah, see, I think it's a different...
Ping Yu: position or different view of saying things. Because for us, for researchers, we would say, "Hey, if we got a pest or disease issue that has a very short life cycle, we can start doing the research and have results fast enough to have some outcomes."
Ping Yu: But from the grower's perspective, they're like, oh, it can replicate so quickly so it can create more damage. And that gives them the headache of, oh, gosh, I have to take actions quicker than they reproduce. So it's a tricky part. For the growers, definitely, it's one of the worst nightmares that you can get from a pest because you cannot even see them. You only see the damage when the plants cannot be saved anymore.
Alexandra Revynthi: So like thrips from a grower perspective is like the worst pest that someone can deal with [VERIFY: audio may say "best" — sarcastic usage].
Ping Yu: Yeah, and they are very tiny, especially for thrips parvispinus, even way tinier than the common western flower thrips.
Ping Yu: and you have to have a hand lens or a magnifying lens to be able to see them clearly. So it's tricky for the growers to detect. Speaking of that, can you share some of the simple, easy ways for the grower to go out and check if they have the pest?
Alexandra Revynthi: So in the cases like these where the insect is very small and we know that it spends part of its life cycle hidden so the eggs are inside the leaves you cannot see them and then the pupae they stay in the soil so again you cannot see them you're searching for three stages pretty much.
Alexandra Revynthi: And they're very small. So we always advise to target the upper part of the canopy, the tender tissue, because this is the one that they like. And they can observe the scars. They can observe stunted growth. So the new tissue is not fully developed normally. You can see it's shriveled. It doesn't look healthy. So we encourage them to try to work with the symptoms. If symptoms are not there, but they still want to monitor, which is good because prevention helps.
Alexandra Revynthi: We always encourage them to do the beating method. It's like pretty much you take a board with you, put a white piece of paper on it, and then you go and you start hitting the canopy against this white piece of paper gently because of course we don't want to damage the plant and then the insects will fall.
Alexandra Revynthi: And of course, with a magnifying lens, thrips parvispinus can be more or less distinguished from the other thrips pests that we have because it has these two colors in its thorax and abdomen. So it has this golden yellow color versus the darker brown or black. So it has these two distinct colors. So if people see this, they can think, okay, I might have this pest.
Alexandra Revynthi: However, for accurate identification, because we do have two more species that are very closely related and they resemble each other, we do need to do the mounting and the formal identification. But this already will tell a grower, okay, I need to be on the lookout, I should bring this specimen to a specialist to
Alexandra Revynthi: help me and let me know what should be my next actions based on the correct
Alexandra Revynthi: identification. But the beating method is certainly a very good first step to set the tone for the management options that are available.
Ping Yu: Yeah, because speaking of the identification, I remember we were in South Georgia trying to collect some of the samples for parvispinus, and we thought we got them. We did get some of them, but we also got the Hawaiian thrips, which is Thrips hawaiiensis.
Ping Yu: And this one is very much like thrips parvispinus. And you have to have very specific training to be able to tell them apart. So basically, if you're a grower out there and you suspect that you have this thrips parvispinus issue in your operation, the best strategy that you have,
Ping Yu: one tip is to call your extension office, say, "Hey, I got this issue. Can you collect the sample and send it to the clinic and do the right identification and then go from there?" Because normally they cannot
Ping Yu: be able to correctly identify those.
Ping Yu: So in your lab, I know that you started working on thrips parvispinus pretty early because it's again,
Ping Yu: started in Florida and you have worked on thrips before. Can you share some of the work that you have done at least from the laboratory evaluation for the chemicals? And can you share some of those results and experiments that you have done on this pest? Alexandra Revynthi: Sure. So as you mentioned, as soon as this pest was found in Florida, there was a lot of regulation.
Alexandra Revynthi: And immediately the ornamental growers that were found with this pest, they were placed under quarantine. And they couldn't have their plants outside the quarantine area unless they had eradicated the pest. At that time, a single individual was enough to place a nursery under quarantine. Only one insect.
Alexandra Revynthi: So you can understand that there was a lot of pressure. Considering that we were very close to the spring shipping season, which is the most intense season for the ornamental growers here in South Florida, you can understand that this
Alexandra Revynthi: could have a potentially large financial impact on them. And actually, it did have four nurseries that were actually placed under quarantine. So the Florida Department of Agriculture and Consumer Services, considering these obstacles, offered the option to the growers to be reinspected within 48 hours after they have issued the quarantine.
Alexandra Revynthi: It was found positive, but it was willing to take all the precautions and all the actions in order to eradicate the pest. They had 48 hours at their disposal and then they could request a reinspection.
Alexandra Revynthi: So that the inspector can come check and if the insects were not there anymore they would release the nursery from the quarantine. Considering these circumstances we started devising a lab assay under this time frame because we needed chemical control that would guarantee a knockdown effect within 48 hours.
Alexandra Revynthi: And of course, because of the regulation and the quarantine, we were not allowed to go and work in nurseries and do the research on the farms or even conduct a greenhouse trial. So everything had to happen in the lab inside the containment facility that we do have here at TREC [VERIFY: may say "REC"].
Alexandra Revynthi: So what we did, we started screening as many registered products for use on ornamentals under nursery conditions that they would have thrips on their label as possible.
Alexandra Revynthi: In total, I think, if I recall correctly, we screened 22 conventional and 11 biorational botanical products and trying to identify which ones they would stand out and they would offer this knockdown effect when they would come into direct contact with the insect.
Alexandra Revynthi: Or if they come into contact with the leaf tissue, and then we offer this sprayed leaf tissue to the insects and feed on it, and then see if they die by ingesting the product. That was the idea. And then, of course, we took into account that we had three feeding stages on the plant. So we have the adult
Alexandra Revynthi: female that we know that these are the insects that increase the population that they lay eggs.
Alexandra Revynthi: So we targeted the adult females as well as the two instars.
Alexandra Revynthi: So the first instar and the second instar nymphs or larvae as we call them.
Alexandra Revynthi: And we tried to identify which of all these products would give us the maximum potential for control.
Alexandra Revynthi: And this is as far as we could go within a lab setting and considering the 48 hours window. So this is how we started. And we were happy to see that there were good options available in the market that the growers could purchase and actually use them.
Alexandra Revynthi: But we were also surprised to see that chemistry, old-fashioned chemistry, that we knew that was very efficacious for thrips, like for western flower thrips, would not work for thrips parvispinus. So then we started understanding why thrips,
Alexandra Revynthi: the growers had such a difficult time managing this pest when they first detected it. Because they started spraying from the beginning but they said no, it doesn't work. And yeah, based on these experiments we came with a short list of potentially good products and as soon as the regulation relaxed a little bit we applied for an additional permit.
Alexandra Revynthi: that would allow us to do greenhouse experiments. And we did that. We did these experiments. And in this case, we used ornamental plants as our host. We worked with mandevillas. We worked also with gardenias. And we tried to see when you spray an entire plant,
Alexandra Revynthi: and it's already infested or if it's not infested and then you try to infest it, whether we would see this potential being translated from the lab to the greenhouse. Of course, the growers couldn't wait for us to finish all this research. So as soon as a lab trial would come to an end, we would immediately share the results with the growers.
Alexandra Revynthi: so that they have more and more options for rotation because we didn't want to enter in a situation where we will cause issues with resistance. And we were happy to know that, you know, by following the products that we had seen already in the lab showing potential,
Alexandra Revynthi: by implementing them appropriately, growers were able to go through the shipping season with smaller disturbance. And the following year, like in 20, actually in 2024, we had actually one relatively smooth shipping season when it comes down to thrips. There were no complaints. Things went very smoothly.
Ping Yu: That's great to hear. I think that's the power of the research and collaboration with universities and industry. We were like, it's a teamwork. But when you mentioned that some of the insecticides you started with a lab
Ping Yu: evaluation for the chemicals and narrow it down to a list of certain chemicals that would work best for thrips parvispinus.
Ping Yu: Can you give us some examples of those tested chemicals that you found are very effective for thrips parvispinus?
Ping Yu: Among them, are there any specific products that can cover both thrips parvispinus and other thrips?
Alexandra Revynthi: To answer that question, yes. Because they are registered for thrips. They would even mention, for instance, western flower thrips in their label.
Alexandra Revynthi: So there were like three products that really stood out. The first one was chlorfenapyr. It is known as Pylon or Piston. That was like the best performing product and we could corroborate the results from the lab also at the greenhouse in two different ornamental hosts.
Alexandra Revynthi: Then we had a relatively new product that is called XXpire [VERIFY]. It's a combination of sulfoxaflor [VERIFY] with spinetoram. This one also showed great potential. Growers already using this product on hibiscus to manage the hibiscus. They were familiar with it and they had access to it.
Alexandra Revynthi: So it was great. Then abamectin, which is known as Avid or Timectin [VERIFY: product name], was the formulation that we evaluated. This one also showed very good results, actually very good results in the greenhouse. In the lab, I think it came, if I recall correctly, came fourth in the list.
Alexandra Revynthi: But in the greenhouse, it really showed potential. It did very well in both cases when it was applied directly on the insects or when it was evaluated as a residue toxicity treatment.
Alexandra Revynthi: And the interesting results that we obtained, we did also see potential in two biorational pesticides that we evaluated subsequently in the greenhouse. The first one was a mineral oil at a 3% concentration. And the second one is a formulation of sesame oil.
Alexandra Revynthi: And we could see in the greenhouse, although we were expecting to see high efficacy when the products would come into direct contact with the insects, because these products work through contact and they suffocate the insects by closing the spiracles or the organs that they use to breathe.
Alexandra Revynthi: We didn't see these effects. However, we saw increased mortality when the plants were treated with this product and then the thrips were released to feed and reproduce. We saw high mortality when the products were already applied on the plants, which was something that we did not expect.
Alexandra Revynthi: But also, we were hopeful that we have two good alternatives to conventional chemistry, that we can use them for rotation and also as alternatives in order to be able to implement other management strategies that are not chemical control.
Ping Yu: When you brought the terminology, biorational insecticides and conventional insecticides, can you explain a little bit what biorational insecticides are? For conventional, I guess, if I understand, it's more like a synthetic insecticide that's from...
Alexandra Revynthi: the chemistry perspective. But what's the difference of those two? Yeah, the conventional, I would say, these are the synthetic insecticides. All of them need an EPA registration number. Some of them might even be restricted-use pesticides and might require a pesticide license in order to be bought and subsequently being applied. Biorational insecticides are
Alexandra Revynthi: defined as the insecticides that they are based and derived from natural resources.
Alexandra Revynthi: One example can be botanical insecticides, so where we have the active ingredient deriving from plants.
Alexandra Revynthi: In the biorationals, we can also put the products that they have as their active ingredients.
Alexandra Revynthi: This is also a category of biorational pesticides, only in this case because it has fungi or it may have bacteria, we call them microbial
Alexandra Revynthi: insecticides. They can have as their active ingredients, components that come from other organisms or plants.
Ping Yu: Yeah, so basically for the biorational insecticides, we can also use the neem oil would be normally used for some pest control.
Ping Yu: Sulfur can be also another example of biorational insecticides.
Alexandra Revynthi: Yes, because it is based in petroleum and it has some sulfates that they might be deriving from non-synthetic components.
Ping Yu: Okay, but when you were doing the greenhouse trial down the road, it actually stood up.
Ping Yu: They became one of the most effective chemistry. What do you think the difference with those two trials? What can you explain why we're seeing those two different results for the same chemistry? Alexandra Revynthi: No, it's not that it did not come to the top. It came to the top and this is why it was selected.
Alexandra Revynthi: But from the short list, it was number 3 or 4, because let's say the number 1 which was chlorfenapyr, it would give us 100% mortality when it was sprayed directly on the insects or as a residue toxicity.
Alexandra Revynthi: And it would result in high mortality in all three different stages. These were the criteria. So this is why, for instance, this particular active ingredient was like number one. Abamectin would still result in very high mortality, close to 90-95%, but this mortality might vary maybe with the application type or the stage of the thrips that was targeted.
Alexandra Revynthi: So why did we observe? The differences that were observed were not outside the norm. It's just that we were expecting to see the same order that we saw in the lab to be translated in the same order in the greenhouse. However, in a greenhouse, you also have fluctuating temperature and humidity.
Alexandra Revynthi: Although we did use a controlled environment and we could even control for the humidity that was approximately at 70%. But it is still a fluctuating environment. In the lab, we used incubators, no fluctuation at all of the temperature and the humidity.
Alexandra Revynthi: And we do know that products like abamectin, they can be sensitive to photodegradation. And of course, it has to do with how you apply the product. But again, what we observed was close to what we were expecting. It's just that it did better than other active ingredients that we tested.
Ping Yu: Oh, okay. That makes sense because sometimes we would say greenhouse is also considered as a controlled environment, but in fact, in reality, we cannot control every bit in there because you got all those ventilation, the cooling pad going on, and you have people constantly come in, open the door. It's nothing like a growth chamber in your lab.
Alexandra Revynthi: So, one of the things that we haven't done is actually build the rotation program. So we only tested each product by itself. And the comparisons were always made, okay, the product versus the control, because this is what makes sense, right? We measure mortality when we compare to the water that was our control.
Alexandra Revynthi: The mineral oil as well as the sesame oil, they offer opportunities for rotation. People should scout before making the decision to apply a pesticide because it might not be necessary. So you don't want to waste your money by buying the product and then paying labor to apply the product. And then you cannot enter because there might be a re-entry restriction, right? So you don't have access. So all this costs a lot of money.
Alexandra Revynthi: So it's better to put the time into scouting, make sure that you do have an issue that you need to resolve, and that the issue is very big, so you need to get a very aggressive, knockdown approach, and then come in with additional strategies.
Alexandra Revynthi: This is not always the case. So if somebody wants, because they have concern, because there is regulation in place and they cannot take risks, then the biorational, like the oils, if the weather permits, because we always have to take into account the temperature, right? If we have very high temperatures, these
Alexandra Revynthi: products should not be used because there are serious concerns with phytotoxicity.
Alexandra Revynthi: Right? But especially during the fall and winter months,
Alexandra Revynthi: we have the opportunity to use these products instead of conventional chemistry.
Alexandra Revynthi: And we can leave the conventional chemistry when we are closer to shipping,
Alexandra Revynthi: so that the growers can comply with regulation and they can ship out of the state plants that do not have the pest.
Ping Yu: Yeah, because I was thinking for anyone who's spraying or who's using the pesticides or insecticides,
Ping Yu: one of the things that they have to bear in mind is rotation. Because with ornamentals we pretty much have limited options for certain pest and disease issues [VERIFY]. So if we keep
Ping Yu: applying the same thing, it just loses the effectiveness of the product and that's not something we can afford because we don't have a whole lot of options out there. But for thrips parvispinus, it has a very large or wide host range. But can you give us some examples of thrips parvispinus's favorite plants? Alexandra Revynthi: If we need to choose one, that will be the bell pepper.
Alexandra Revynthi: That's the number one host plant. And this is why in Europe they started calling it the pepper thrips. Although its common name is short spine thrips. So pepper is the preferred host and we have documented research but also evidence from the growers community. Especially here in Florida we had a grower in the beginning of the situation with the invasion of thrips parvispinus where a grower lost the entire crop.
Ping Yu: Yeah, because thrips parvispinus was first originated from Indonesia, if I remember right, in the pepper fields. That's why I think that's how it became a devastating pest in there and then come all the way to the U.S. And then I guess for the ornamentals,
Alexandra Revynthi: mandevilla and gardenia are the... For ornamentals, gardenia is number one, for sure [VERIFY]. Mandevilla is the second. Although you will hear from the growers, they battle heavily. And thrips parvispinus on mandevilla, they see the scars, they see the thrips. It's a constant problem. If you talk with researchers that are trying to work with this thrips species on mandevillas,
Alexandra Revynthi: they will tell you it's impossible.
Ping Yu: It's hard.
Alexandra Revynthi: I haven't met a colleague just yet to tell me,
Alexandra Revynthi: I have a colony of thrips parvispinus on mandevilla.
Ping Yu: What is the...
Ping Yu: Can you tell us a little bit about the dip treatment experiment?
Ping Yu: Is that the same?
Ping Yu: I think it's different from the laboratory evaluation for chemistries and the greenhouse
Ping Yu: trials you have done.
Alexandra Revynthi: Give us some hint for that experiment. So this experiment also took place in the containment facility that we have. But the idea behind it was what if we start the crop clean? So we want to do IPM, but it's easy to do IPM and to implement biological control and other practices when the pest pressure is very low. So start clean, we are already ahead of the game.
Alexandra Revynthi: And mandevillas and gardenias and hibiscus, all of those are propagated through cuttings. So, and taking cuttings is a very standard practice for the ornamental industry as a whole, but also for the ornamental industry here in South Florida.
Alexandra Revynthi: So we explored the potential of treating these cuttings before they even are stuck, before they are rooted, and see the potential of these treatments against the second instar larvae, which was found to be a very aggressive stage. They could cause a lot of damage. So we targeted the stage and we did the research on beans.
Alexandra Revynthi: Because we had an adapted population on beans and we wanted to see if the treatments were going to work. And we evaluated treatments, we evaluated products that were available in the market, number one. And number two, they were allowing dipping in their label. Because not all products can be used as a dip treatment. It has to specify in the label that you can use them as a dip treatment.
Alexandra Revynthi: So we identified these products and we went with a maximum label rate for dipping in this case. So at that time, the Suffoil-X, which is a mineral oil at 2% concentration, it had got an emergency exemption for dipping for thrips parvispinus because they had already seen great potential. In Canada, they do treatments for cuttings against thrips for many years now, successfully, targeting the western flower thrips.
Alexandra Revynthi: So, Canada already has Suffoil-X, which is the product with dipping in its label. In the US, we didn't have it up until recently. They asked for an exemption in the label for this particular species to apply mineral oil, Suffoil-X, as a dip treatment.
Alexandra Revynthi: So we included it in the list and there are also some microbial products that they had. They were formulations of Beauveria bassiana either as a wettable powder or as an emulsified concentrate. So pretty much we gently dipped the beans [VERIFY] and we evaluated how first they were of course infested with the thrips larvae.
Alexandra Revynthi: Then we dipped them, and then we evaluated how many thrips larvae were dislodged, just by simply dipping them into the solution. And from the ones that they were not dislodged, how many survived and how many died over time.
Alexandra Revynthi: So we did that and we saw already that the mineral oil and the oil formulation of Beauveria bassiana were really showing great potential. They could dislodge more than 80% of the thrips population, which was great.
Alexandra Revynthi: But this potential was seen on beans, right? But when you treat ornamental materials, you need to make sure that the quality of the plant is not going to be affected. So we took cuttings from gardenias and mandevillas that we had, and we treated them with the solutions, with all the solutions, and then we measured phytotoxicity.
Alexandra Revynthi: to make sure that we're not going to damage the cuttings. And then, of course, we stuck them, so we let them root and everything. And we saw, indeed, that the mineral oil that had got this exemption in the label was the best-performing treatment, and it was the treatment that did not cause phytotoxicity.
Ping Yu: Yeah, so basically there are some products that will be better helping the growers to manage this pest from the beginning. And actually Rosa is going to talk to me on this in another episode. So I'm very excited to hear her research on this. What do you think are the research gaps that still needed to be filled for a better control of this pest?
Alexandra Revynthi: I know there are different groups working on this pest, but what are the research gaps? So, currently we are in the process of publishing a couple of manuscripts that we have and we are preparing a couple of more on the potential of biological control in the system because we cannot continue using chemical control without
Alexandra Revynthi: the fear of getting resistance and of course for the impact on the human health as well as the environment.
Alexandra Revynthi: So we have identified predatory mites, predatory insects, entomopathogenic fungi, and entomopathogenic nematodes
Alexandra Revynthi: that can be considered as biocontrol agents against thrips parvispinus. So we are hopeful that soon we will be able to share with the scientific community this information. We have already shared this with the public, this information, because
Alexandra Revynthi: we, as you said, we host webinars and we try to maintain the growers up to date about our research so that they can see which tools can be suitable for their operation. But I think as we move forward, the most important is to find a way to integrate all these different tools that we have identified. So I think this is where we stand right now.
Ping Yu: Try to bring together all the strategies and make them work in a synergistic way so that we can achieve the best management possible. Yeah, I agree. Because right now, I think different groups are working on different perspectives. And to a certain point on the road, we need to gather everyone together and then
Ping Yu: provide every piece in there and solve the puzzle altogether.
Ping Yu: What are some of the next steps that you are excited about besides thrips parvispinus, just the research that you are interested in?
Alexandra Revynthi: Interesting question. So, I want to dive a little bit more on the thrips and I want to try and understand a little bit more the plant and thrips interactions and try to understand why we observe different things in the lab versus the field, especially trying to understand what is happening with mandevillas. The project that we have together is already giving us this opportunity to answer these questions.
Alexandra Revynthi: So we have a new invasive pest. The two-spot cotton leafhopper. This is another challenging pest. Very strict regulation in the sense that it's a pest of okra and cotton. So we're talking about a commodity like cotton is a very important crop for the entire country.
Alexandra Revynthi: So this is a big challenge that we have ahead. And I hope because there are a lot of many good scientists already working on that from different crop angles, from the vegetable side, from the hibiscus side, from the cotton side. So I'm really hopeful, looking forward to see what the research is going to show and how we can all together find ways to mitigate this invasive pest. Ping Yu: I know that you have passion for plants and now you are working for...
Ping Yu: for ornamental pest control. But if I ask you, what is your favorite plant, what would you say? Alexandra Revynthi: Orchids. Phalaenopsis orchids, yeah. Ping Yu: Why? Alexandra Revynthi: Because they're so beautiful. I feel admiration for the plant. I find it so aesthetically pleasing. So like for me, this is like my top.
Ping Yu: Yeah, and it's very elegant. But is Greece a big orchid producer? Do you grow up seeing orchids around you?
Alexandra Revynthi: They're popular. I had several orchids while I was living in Greece. None of them survived. That's another story.
Alexandra Revynthi: Yeah, but I wouldn't say that Greece is like a top contender in orchid production. Of course not.
Alexandra Revynthi: But yeah, we do have orchids in Greece.
Ping Yu: Okay, so the reason why I ask you if you grew up with the orchids around you, because for a lot of people, if people have to choose one of their favorite plants, there's always linkage or connections between their home with the plant or some emotional or cultural link here and there. So that's why I ask you about that.
Ping Yu: But with that in mind, if people want to go look, find more of your research, Alexandra, work or your other research, where do you recommend them to go and look? Alexandra Revynthi: Yeah, we try to keep up to date. We have a webpage that is dedicated to thrips parvispinus.
Alexandra Revynthi: This is where we upload the webinars that we do, the recordings of the webinars. In earlier stages of the research, we would even upload the PowerPoint presentation so that people could access the content at their time and review it and see the rates that we use and the products that we evaluated.
Alexandra Revynthi: And we also try to put links of the publications. So we have these webpages that we keep on updating.
Ping Yu: Yeah, I'll add all those links to the show notes. But thank you for taking your time out of your busy schedule to talk with us on this topic. And I really enjoyed it.
Alexandra Revynthi: Thank you very much for the invitation.
Ping Yu: Thank you.
Ping Yu: Besides the resources that our guest speaker shared with us today, AFE also has additional resources on thrips. Please go to the AFE Thrips and Botrytis Research Library and find more resources on thrips parvispinus and botrytis. This episode in our first season is made possible through an educational grant from the American Floral Endowment.
Ping Yu: The research priorities helped shape the topics that are featured. To learn more about AFE and access their research and educational resources, visit their website at endowment.org. Conversations like this only happen when you support the show. For more information and find ways to support us,
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Ping Yu: And as always, go check out the show notes to learn more about this topic and other topics we featured on the show at bandbpod.com. Thank you for listening. Till the next time, stay healthy and go plants!