Bodie Pennisi: Welcome back, everyone.
Bodie Pennisi: Our second speaker is Dr. Ignazio Graziosi, who is an assistant professor in Warnell School
Bodie Pennisi: of Forestry at University of Georgia.
Bodie Pennisi: Dr. Graziosi studies tree health and raises awareness of the benefits provided by trees.
Bodie Pennisi: As a field biologist, he has studied the impact of invasive species.
Bodie Pennisi: insects and microorganisms on tree health and used this knowledge to develop management
Bodie Pennisi: and surveillance tools while engaging land managers and the public in education programs.
Bodie Pennisi: In his early career as a forester, he focused on the management of natural and urban tree
Bodie Pennisi: Dr. Graziosi has held positions with non-governmental and governmental organizations, universities,
Bodie Pennisi: and private companies in different countries.
Bodie Pennisi: His work involves field and laboratory studies, data collection and analysis, development of
Bodie Pennisi: protocols, use of photography, team project and partnership coordination, capacity building,
Bodie Pennisi: education and analysis.
Bodie Pennisi: outreach. And Dr. Graziosi, the floor is yours from Italy.
Ignazio Graziosi: Thank you. Thank you, Bodie. Good afternoon, everybody.
Ignazio Graziosi: Give me one sec that I'm going to click the magic button.
Ignazio Graziosi: All right.
Ignazio Graziosi: Can you hear me all right and see my screen?
Ignazio Graziosi: Yeah.
Ignazio Graziosi: Yes.
Ignazio Graziosi: Fantastic.
Ignazio Graziosi: Okay.
Ignazio Graziosi: It's great to be here.
Ignazio Graziosi: Looks perfect.
Ignazio Graziosi: Thank you again.
Ignazio Graziosi: So we are all dealing with the variety of different tree pests.
Ignazio Graziosi: You can see on the screen a couple of examples.
Ignazio Graziosi: There is a woolly adelgid.
Ignazio Graziosi: We have fall webworm, caterpillar, beetles.
Ignazio Graziosi: scales, and we tend to concentrate on the pest itself because it's what
Ignazio Graziosi: produces damage to our trees. But it is important to remember that it is always a
Ignazio Graziosi: team result. We have the pest, yes, but there are other actors in
Ignazio Graziosi: In the picture that caused the overall damage, of course, we have the tree itself and we have the environment.
Ignazio Graziosi: And the damage on the tree, the damage from the pest and from the disease, is caused by the interaction of these three components.
Ignazio Graziosi: And this is the concept of the disease triangle.
Ignazio Graziosi: So the damage is not caused by just one component.
Ignazio Graziosi: The pest alone is not enough, but is the interaction with the tree, which, for example, is susceptible, and the environment.
Ignazio Graziosi: And we are dealing with trees, especially in the landscape, for the focus of this webinar, and in urban environment.
Ignazio Graziosi: And in those environments, the situation gets worse.
Ignazio Graziosi: And I introduced to you that spiral of tree decline.
Ignazio Graziosi: And this is a diagram that was developed in the 90s and is really useful to understand this concept one step more.
Ignazio Graziosi: So how does this diagram work?
Ignazio Graziosi: So you see three different levels of spirals.
Ignazio Graziosi: Each spiral is a family of factors that add stress to the tree at different levels.
Ignazio Graziosi: A lot of those are similar to the stressor that Dr. Klein presented at the beginning of his presentation.
Ignazio Graziosi: And all these different family of stressors, they end up eventually with the death of the tree.
Ignazio Graziosi: And you see at the center of the death spiral, there is in fact the death of the tree.
Ignazio Graziosi: And if we look at those three spirals one by one, we can see, for example,
Ignazio Graziosi: the first one that is called the predisposing factor.
Ignazio Graziosi: general stressor. The urban environment of course is stressful for the tree, there is the genetic
Ignazio Graziosi: potential of the tree itself, and again it's a demonstration that the disease triangle is really
Ignazio Graziosi: important. And then we have well-known stressor like soil compaction, which is often the number one issue for many
Ignazio Graziosi: trees. And then we have another spiral that is closer to the center of our death spiral,
Ignazio Graziosi: which is called here inciting factor, and we have defoliating insects, for example, we have drought
Ignazio Graziosi: And then we have an even more internal spiral which is contributing factor,
Ignazio Graziosi: and you see a lot of biotic factor.
Ignazio Graziosi: You have fungi, wood boring insects, nematodes, Armillaria for example.
Ignazio Graziosi: The important thing to understand of this diagram is that each of the spiral, the predisposing factor, the inciting factor, and the contributive factor, contain factors that can directly bring the tree to death.
Ignazio Graziosi: If you see, I'm not sure if you are able to see my pointer that I'm using on the screen.
Bodie Pennisi: Yes, we are.
Ignazio Graziosi: Fantastic.
Ignazio Graziosi: Thank you, Bodie.
Ignazio Graziosi: And you can see these lines here.
Ignazio Graziosi: These lines means that each of these factors, for example, urban environmental factors,
Ignazio Graziosi: urban environment alone or soil compaction alone are able to cut through the different
Ignazio Graziosi: layers of the spiral and bring the tree directly to death.
Ignazio Graziosi: One important message to take home from this diagram is that the health of the tree and
Ignazio Graziosi: potentially the death of the tree is an interaction between many factors.
Ignazio Graziosi: And if we go back to our slide, visualizing different pests that we have to deal with,
Ignazio Graziosi: we have here non-native pests.
Ignazio Graziosi: We have examples of native pests.
Ignazio Graziosi: We have examples of native trees, examples of also exotic trees.
Ignazio Graziosi: And understanding the interaction among those native pests,
Ignazio Graziosi: attacking native trees and vice versa, non-native attacking native and native attacking non-native
Ignazio Graziosi: is really important because allow us to understand the mechanism
Ignazio Graziosi: and to understand what are the general strategies we can use to manage and control those pests
Ignazio Graziosi: and this is true for many different pests.
Ignazio Graziosi: So I'm bringing to you three examples,
Ignazio Graziosi: three stories if you want,
Ignazio Graziosi: that investigate, explore different scenarios
Ignazio Graziosi: and present to us some important component of this interaction
Ignazio Graziosi: that will help us to deal in the future with a variety of different pests.
Ignazio Graziosi: So the first one, the first example, the first story for you is a native tree impacted by non-native pest.
Ignazio Graziosi: And this is the very famous case, the superstar of insect pests, the emerald ash borer.
Ignazio Graziosi: So the emerald ash borer, I'm sure many of you are familiar with it on the picture on the left,
Ignazio Graziosi: is a canopy dieback caused by the insect.
Ignazio Graziosi: And remember, when you see canopy dieback caused by the emerald ash borer
Ignazio Graziosi: and you identify the problem to be that, the emerald ash borer,
Ignazio Graziosi: that means that the insect has been spreading in the area for at least 5 to 10 years.
Ignazio Graziosi: And then you see on the right that is the damage at a stand or forest level.
Ignazio Graziosi: So a very quick summary of what is the EAB, emerald ash borer, about.
Ignazio Graziosi: So larvae feed under the bark and doing so disrupt the phloem, the cambium, the outer xylem,
Ignazio Graziosi: and it cuts off the movement of nutrient and water.
Ignazio Graziosi: And trees, they can die very fast.
Ignazio Graziosi: This is an overview of how the damage happened.
Ignazio Graziosi: And if you start from the picture on the left, you see a young tree that is debarked, and
Ignazio Graziosi: you see the gallery caused by the feeding larvae, and you see that the tree is desperately
Ignazio Graziosi: trying to sprout.
Ignazio Graziosi: has a reaction to the attack and the water sprouts are actually a very important diagnostic
Ignazio Graziosi: feature in order to understand if a tree is attacked by the emerald ash borer.
Ignazio Graziosi: And if you get closer to the tree, you can actually see the larvae, like here, that is feeding.
Ignazio Graziosi: This is a fourth instar, is a mature larva, is probably around two inches long,
Ignazio Graziosi: And by feeding, it basically disrupts all the cambium tissue and the outer xylem.
Ignazio Graziosi: And then, after the larva, completed the larva development,
Ignazio Graziosi: which is usually at the end of the season,
Ignazio Graziosi: it folds in a J-shape and gets a little bit deeper in the outer wood,
Ignazio Graziosi: and it starts kind of slipping, and overwinter is called J-larva, or prepupa.
Ignazio Graziosi: pupa. And then at the end of the winter, pupate and emerge in spring. You can see the shiny
Ignazio Graziosi: green beetle that is emerging from a tree. And while it emerge, it leaves through a very
Ignazio Graziosi: characteristic, the famous D-shaped exit hole.
Ignazio Graziosi: This is another way to represent the life cycle of the insect.
Ignazio Graziosi: We can start from here, where the insect again comes out from the tree,
Ignazio Graziosi: leaving the D-shaped hole, and then mate, female, lay eggs in the crack of the barks.
Ignazio Graziosi: from the egg, a larva hatch goes through the bark and starts feeding and causing the gallery you already seen on the previous photos.
Ignazio Graziosi: And then pupate and will emerge again the following years.
Ignazio Graziosi: Here it is important to remember that this is usually mostly a one generation per year insect.
Ignazio Graziosi: But there is always a part of the population of the emerald ash borer in any location
Ignazio Graziosi: that requires two years instead of one to develop.
Ignazio Graziosi: And this is true especially in the northern part of North America,
Ignazio Graziosi: where temperatures are lower.
Ignazio Graziosi: As we know, temperature usually increases the development of insects.
Ignazio Graziosi: And so the colder it is, the slower it develops. So at northern latitude in North America, the
Ignazio Graziosi: emerald ash borer, a larger part of the local populations of emerald ash borer,
Ignazio Graziosi: required two years to develop. And it is important to know when we have to deal with this insect to control it.
Ignazio Graziosi: It was found, was discovered in 2002 in the Detroit area, which means again, as I pointed out earlier, that was present in the area already at least for 10 years.
Ignazio Graziosi: And then you see all the little red dots.
Ignazio Graziosi: Yes, it took North America, as we know, by storm.
Ignazio Graziosi: This is one of the last available map from USDA.
Ignazio Graziosi: This is 2023, because in 2021, I believe, the quarantine was lifted.
Ignazio Graziosi: at federal level.
Ignazio Graziosi: It was lifted because there was no hope to contain the insect through quarantine.
Ignazio Graziosi: And then the invasion of North America by the EAB was caused by one single individual cause.
Ignazio Graziosi: There was one culprit that allowed the EAB to move so quickly all over the United States.
Ignazio Graziosi: And I let you guess and you can write your answer if you have an idea in the chat box.
Ignazio Graziosi: I will not be able to see it right now, but I will go later and check.
Ignazio Graziosi: And this is, of course, firewood.
Ignazio Graziosi: campers and travelers, they move infested firewood to the next city, to the next country,
Ignazio Graziosi: to the next state.
Ignazio Graziosi: And this really is what determined a lot of the pathways of the invasion in North America.
Ignazio Graziosi: They were able to connect very closely the pattern of the spread with the highway and
Ignazio Graziosi: freeway system.
Ignazio Graziosi: There is one good thing that came out from this disaster, which is the "Don't move firewood" campaign.
Ignazio Graziosi: This is a very effective and important campaign that helps, for example, contain other invasive insects, such as the Asian longhorn beetle.
Ignazio Graziosi: Okay, so we know that as the EAB spread in North America, attacked and impacted heavily
Ignazio Graziosi: the native species of ash.
Ignazio Graziosi: In Georgia, for example, there is of course the emerald ash borer, and this is a spread, is
Ignazio Graziosi: I would say the southern edge of the invasion, so it's still spreading.
Ignazio Graziosi: This map is from 2020.
Ignazio Graziosi: So there is active surveillance is present in the Athens area, of course, and even a little bit southern. So you may think that is not very important, is not as important as
Ignazio Graziosi: fighting against the emerald ash borer in Georgia comparing to other states.
Ignazio Graziosi: It's true, there are other states where there is a continuous presence and availability of ash
Ignazio Graziosi: and Georgia is more scattered. But if we start looking at the distribution of ash species
Ignazio Graziosi: in Georgia, we see that it is really important for biodiversity and actually the state hosts
Ignazio Graziosi: multiple species of ash.
Ignazio Graziosi: We have green ash statewide, we have blue ash, which is an interesting tree because it shows
Ignazio Graziosi: a little bit of resistance against the emerald ash borer.
Ignazio Graziosi: It will die eventually, but it will take way longer compared to other species of ash.
Ignazio Graziosi: We have white ash, Carolina ash, which is a southern ash.
Ignazio Graziosi: We have Biltmore ash, which is a subspecies of white.
Ignazio Graziosi: We have pumpkin ash on the southern part of the state,
Ignazio Graziosi: swamp white and small ash.
Ignazio Graziosi: And then there is another plant,
Ignazio Graziosi: that unfortunately is important for the ecology of the emerald ash borer, and is a surprise that happened in 2014,
Ignazio Graziosi: when they discovered that the EAB was able to, we say, expand its host range and attack a native
Ignazio Graziosi: plant in North America, which is the white fringetree, which is the same family, Oleaceae,
Ignazio Graziosi: of ash.
Ignazio Graziosi: And this is present also in Georgia.
Ignazio Graziosi: It's important to know that because not only it could be a damage for the white fringetree,
Ignazio Graziosi: but more importantly, the white fringetree could function as a reservoir for the population
Ignazio Graziosi: of the EAB, even though
Ignazio Graziosi: all the other ash trees in the area are gone.
Ignazio Graziosi: So the EAB can stay in an area utilizing the white fringetree.
Ignazio Graziosi: Okay, so we know that the EAB is non-native and we know that it is from Asia.
Ignazio Graziosi: So if we look at the map where it was in Asia and where it is now in North America spreading
Ignazio Graziosi: and causing damage, we may ask how did it get there? Of course we know through
Ignazio Graziosi: trade. This is a photo in the port of Savannah. And we know that this not accidental introduction
Ignazio Graziosi: through trade of non-native species is not a new trend, but is an exponentially increasing trend.
Ignazio Graziosi: And you can see here an example from different parts of the world.
Ignazio Graziosi: So it is really exponentially increasing.
Ignazio Graziosi: One reason is that our ability to detect species has increased as well, improved.
Ignazio Graziosi: But trade is increasing, of course, and the introduction of non-native species is reflecting
Ignazio Graziosi: this globalization.
Ignazio Graziosi: If you go near potential port of entries, such as airport and port, you may notice traps.
Ignazio Graziosi: This is a generic trap in the port of Savannah.
Ignazio Graziosi: This is another example since we are talking about the EAB.
Ignazio Graziosi: This is the trap that is designed to catch the EAB.
Ignazio Graziosi: is a series of funnel, interconnected funnel. There is a pouch, which is the green pouch there,
Ignazio Graziosi: that is a lure that produces an attractant for the EAB. The EAB arrives,
Ignazio Graziosi: hits the funnel, and it falls in the cup. So this trap,
Ignazio Graziosi: These type of traps, they are not designed to catch as many beetles as possible to remove
Ignazio Graziosi: them from the environment.
Ignazio Graziosi: It's just a detection, but it's a very important detection methodology.
Ignazio Graziosi: Okay, we know of the damage, has the EAB spread in North America, it caused immense damage
Ignazio Graziosi: to the native population of ash.
Ignazio Graziosi: And we have another tool here I want to present.
Ignazio Graziosi: to you, because it's a useful tool to understand the strategy to manage non-native and native
Ignazio Graziosi: pests alike, which is the invasion curve. This is a diagram that illustrates the growth
Ignazio Graziosi: of a population of a pest, which here is called pest prevalence, over time.
Ignazio Graziosi: So the story starts with the introduction when the pests arrive in the area.
Ignazio Graziosi: So the introduction, of course, after the introduction the population of the pests, the prevalence is still low.
Ignazio Graziosi: And then start growing and start multiplying and feeding on the host.
Ignazio Graziosi: And then it enters exponential growth.
Ignazio Graziosi: And this is when land managers, for example, start to be aware.
Ignazio Graziosi: And it's a little bit more time before the public starts to be aware.
Ignazio Graziosi: And by the time the public starts to be aware,
Ignazio Graziosi: usually the population is already really high until it reaches a...
Ignazio Graziosi: plateau which is the so-called carrying capacity what is that for example is where or when all the ash-trees in the area are gone so the population of the pest cannot grow any more this diagram is important
Ignazio Graziosi: because it can be connected with our ability to deal and control the pest.
Ignazio Graziosi: When the population is really low, right after the introduction, we can even try to eradicate a pest.
Ignazio Graziosi: Of course, it's very difficult, but in some cases, for some pests, it's not impossible.
Ignazio Graziosi: We can do prevention, for example.
Ignazio Graziosi: But then as the pest prevalence starts to grow, it's really impossible to eradicate.
Ignazio Graziosi: And then the only control that is possible is a local control.
Ignazio Graziosi: For example, just trying to save individual trees.
Ignazio Graziosi: But as the prevalence and the difficulties of controlling a pest grows, the cost associated with the control grows as well. And this is really important to understand. And this is why...
Ignazio Graziosi: detection is so important and ideally we want to have effective tools to detect a
Ignazio Graziosi: test as close to the introduction event as possible because everything is easier
Ignazio Graziosi: and is possible.
Ignazio Graziosi: Okay, so as we understand how an invasion works, we can look at the map again and we
Ignazio Graziosi: can ask ourselves, okay, we know that the emerald ash borer is non-native, is from Asia.
Ignazio Graziosi: And is a pest here, but what about in its native range? What about in Asia? Was a pest? The answer is no. And there are multiple reasons for that, and they will relate to our disease triangle. We will see that.
Ignazio Graziosi: The first reason is that the native species of ash in Asia, they say co-evolved with the pest, which means they are less susceptible or resistant.
Ignazio Graziosi: And the only ash trees, Asian species of ash trees, that can be attacked by the EAB in Asia are very weak and stressed trees.
Ignazio Graziosi: That's one important reason. And this is why the low susceptibility and the resistance, this is why one of the approaches to control the EAB is to artificially make
Ignazio Graziosi: actually resistant through chemical protection.
Ignazio Graziosi: Of course, this is just a visual summary of the technology that I'm sure you are familiar
Ignazio Graziosi: to.
Ignazio Graziosi: There is three injection, bark spray, and soil drench.
Ignazio Graziosi: I want to give just a little flash and overview of the chemical control methodology for the
Ignazio Graziosi: EAB.
Ignazio Graziosi: And there are few involving systemic insecticides.
Ignazio Graziosi: Some of them, they can be applied by homeowner.
Ignazio Graziosi: Some of them, of course, they need a professional applicator.
Ignazio Graziosi: And you have to choose carefully which one, depending on the season, for example, soil
Ignazio Graziosi: drench needs to be applied in the spring before leaves are out.
Ignazio Graziosi: I leave you here two links, two QR codes.
Ignazio Graziosi: I encourage you to check them.
Ignazio Graziosi: One is an overview of the state, the status, and the control of the EAB in Georgia.
Ignazio Graziosi: And the one on the bottom on the left is the full protocol for insecticide control for the
Ignazio Graziosi: EAB.
Ignazio Graziosi: Ok, we are still trying to answer our question why is not a problem in Asia.
Ignazio Graziosi: One reason is the trees are resistant, but there is another reason.
Ignazio Graziosi: The other reason is that the population of the EAB there is kept in check by a community
Ignazio Graziosi: of natural enemies.
Ignazio Graziosi: These are predators.
Ignazio Graziosi: are parasitoids, and we will see later what is a parasitoid,
Ignazio Graziosi: that are able to attack the EAB and to keep the population low.
Ignazio Graziosi: Ok, so why don't we bring them over? That's exactly what we did.
Ignazio Graziosi: And this is called importation biological control, where you go there, you study the
Ignazio Graziosi: natural enemies that are effective in native range, and you bring them over.
Ignazio Graziosi: USDA did that after risk assessment and introduced few different species.
Ignazio Graziosi: And you see here three tiny wasps.
Ignazio Graziosi: And those wasps are parasitic wasps or parasitoids.
Ignazio Graziosi: The first two, the one on the left and the one on the center, they attack the larvae of the EAB.
Ignazio Graziosi: The one on the right attacks the eggs.
Ignazio Graziosi: And those are specialists.
Ignazio Graziosi: What it means is that they only attack the EAB.
Ignazio Graziosi: They don't attack any other insect.
Ignazio Graziosi: And so this warrants success in a way,
Ignazio Graziosi: because they cannot start attacking another insect and kind of waste their potential.
Ignazio Graziosi: How do they work?
Ignazio Graziosi: Okay, let's start with the first one here, the one on the left.
Ignazio Graziosi: And you see it's a small wasp and has a kind of a long tail.
Ignazio Graziosi: Its tail is an ovipositor, and it uses its ovipositor to find trees that are infested with the EAB and drill through the bark
Ignazio Graziosi: is able to use vibrational cues to understand if there is a larva under the bark and exactly where it is,
Ignazio Graziosi: and it stings the larvae of the EAB and it puts its own eggs in the larvae.
Ignazio Graziosi: Think about the movie Alien, Alien 1, not Alien 3, because the life cycle in Alien 3
Ignazio Graziosi: gets very complicated, but in Alien 1 is exactly how it works.
Ignazio Graziosi: Inside, there will be the larvae of the wasp that feeds in the body of the larvae of the
Ignazio Graziosi: EAB, eventually consuming the whole animal.
Ignazio Graziosi: The infographic that you see on the slide is the technology that is used to release it.
Ignazio Graziosi: This is a log prepared in the lab that is filled with larvae of the EAB infested with
Ignazio Graziosi: the parasitoid wasp.
Ignazio Graziosi: You hang them on a tree, the wasp, the adult wasp, they will eventually fly out and find
Ignazio Graziosi: other trees infested with the EAB to be parasitized.
Ignazio Graziosi: The second one is the egg parasitoid. I think you know the story now. It works exactly the same way that it attacks eggs.
Ignazio Graziosi: The technology is a small container. You can see in the picture on the bottom right here is a drug container, drugstore container, is called the O-binator.
Ignazio Graziosi: It contains a paper where there are eggs of the EAB that have been parasitized with this parasitic wasp.
Ignazio Graziosi: Look now at the picture in the center.
Ignazio Graziosi: These brown circles are the eggs of the EAB.
Ignazio Graziosi: If you look at the one on the bottom, you can see that inside there is actually a tiny baby larvae of the EAB.
Ignazio Graziosi: that is waiting to hatch. But if you look at the other two, the dark ones, you see that
Ignazio Graziosi: inside there is something different. That is the wasp that is ready to emerge. Okay,
Ignazio Graziosi: So we understand about biological control now, the importation of biological control,
Ignazio Graziosi: but you may ask, "Okay, so we are in North America.
Ignazio Graziosi: What about our native natural enemies?"
Ignazio Graziosi: The answer is, "Yes, we have some."
Ignazio Graziosi: There are many species that have been described of parasitic wasps or other types of insects,
Ignazio Graziosi: but those are not specialists.
Ignazio Graziosi: They can attack also other types of insects.
Ignazio Graziosi: So they are not effective in providing, they cannot be the only ones that can provide control.
Ignazio Graziosi: Alone, they are not enough.
Ignazio Graziosi: So, at the end of the story, what we want to reach for the EAB, and in general for many non-native pests attacking native trees, is balance between the susceptibility of the plant.
Ignazio Graziosi: and the community of natural enemies, both native natural enemies and also biological control.
Ignazio Graziosi: But also in the picture there is also the chemical protection that is really important, especially to save
Ignazio Graziosi: trees of great value. Because it's true that biological control in North America for the
Ignazio Graziosi: EAB hasn't been fully successful yet, but we can still save large trees of big value
Ignazio Graziosi: in the city and the landscape using chemical protection.
Ignazio Graziosi: Okay, so we are ready for our second example, a non-native tree that is attacked by a non-native pest.
Ignazio Graziosi: And this is an example that may be relevant for us in the south, which is the crapemyrtle bark scale.
Ignazio Graziosi: So the crapemyrtle bark scale, you can see here in the center, is of course a non-native
Ignazio Graziosi: scale attacking our beloved crapemyrtle.
Ignazio Graziosi: There is a huge crapemyrtle culture in the south, there are hundreds I think of different
Ignazio Graziosi: belonging to different species is not only Lagerstroemia indica, but there are hybrid of different species,
Ignazio Graziosi: different color, flower, texture of the bark, size, and of course, it's easy to be judgmental
Ignazio Graziosi: toward the crapemyrtle because it's so commonly used and you can say it's used too much.
Ignazio Graziosi: It's true.
Ignazio Graziosi: It's easy to be judgmental, but it's important to remember a couple of things.
Ignazio Graziosi: One is that crapemyrtle, they provide benefits.
Ignazio Graziosi: And you can see here a little report that has been prepared using this tool called iTree.
Ignazio Graziosi: If you are not familiar with the iTree, it is a suite of different tools that can be extremely useful to calculate benefits,
Ignazio Graziosi: so-called ecosystem services of trees, but also can be used to select the right tree for the right place.
Ignazio Graziosi: The second reason is that regardless of how much the crapemyrtle is planted in the south, we have to deal with this pest because it will create damage.
Ignazio Graziosi: We will have to deal with removal of attack trees or the control of the pest itself.
Ignazio Graziosi: Okay, so the crapemyrtle bark scale, starting from the picture on the left.
Ignazio Graziosi: This is a twig of a crapemyrtle, of course you see the white specks, those are individual,
Ignazio Graziosi: mostly female of the crapemyrtle bark scale, CMBS in short. Why is black? Because like aphids,
Ignazio Graziosi: Of course, scale, while they feed, they secrete droplets of sugary sap.
Ignazio Graziosi: And so black sooty molds, they grow on that.
Ignazio Graziosi: On the picture in the center, different things.
Ignazio Graziosi: Those white lumps are mostly mature females of the scale,
Ignazio Graziosi: but you can also see here immature female nymphs.
Ignazio Graziosi: And this is important for the life cycle.
Ignazio Graziosi: On the right you see a female and if you flip the female you see the eggs.
Ignazio Graziosi: Those very nice pink color are eggs.
Ignazio Graziosi: The life cycle involves both males and females. The male is actually winged, the female is not winged, and a mature female lose legs and cannot move.
Ignazio Graziosi: One of the things complicated the control is that it's not clear how many generations there are. They describe up to five generations, but the problem is that they are overlapping. So at one point, at any point, you may find different stages of the insect.
Ignazio Graziosi: If I go back one slide, the picture in the middle here has been shot one month ago in Athens,
Ignazio Graziosi: so in the winter. And you can see there are nymphs and adults. The nymphs are called crawlers.
Ignazio Graziosi: Okay, what is the situation?
Ignazio Graziosi: Was found in 2004 in Texas, of course huge crapemyrtle culture state, and then in 2014
Ignazio Graziosi: in Georgia, and only in 2018, unfortunately, was found in nursery in Georgia.
Ignazio Graziosi: The QR code I put there is a summary of the status and the biology of the crapemyrtle
Ignazio Graziosi: bark scale from UGA.
Ignazio Graziosi: So if you are interested, please snatch that.
Ignazio Graziosi: Okay, so we already know the invasion curve, what it means, and it's really important for
Ignazio Graziosi: the crapemyrtle bark scale, even though it's already present in the south, even though it's already
Ignazio Graziosi: present in Georgia, to be able to detect it as soon as possible.
Ignazio Graziosi: It's not everywhere yet.
Ignazio Graziosi: In Athens, it got there, I think, in 2021.
Ignazio Graziosi: And you can see it in high numbering for some trees, but there are a lot of trees.
Ignazio Graziosi: They have a very low infestation.
Ignazio Graziosi: So I would say we are at the beginning of the invasion in a lot of places in Georgia.
Ignazio Graziosi: So we are in the situation where we can do well because we are at the point on the invasion
Ignazio Graziosi: curve.
Ignazio Graziosi: where the population is not so high again, that our control can mean something.
Ignazio Graziosi: Alrighty, let's go back to our well-known map.
Ignazio Graziosi: So we know that it is a non-native, come from Asia.
Ignazio Graziosi: So we may ask, "Okay, what about the host there?"
Ignazio Graziosi: The bad news is that this insect in native Asia can feed on many different species of plant.
Ignazio Graziosi: It's not a specialist, so it can feed on apple in Asia, and soybean has been found on fig.
Ignazio Graziosi: One good news is that since there are so many, so they were able to find some cultivar, some species of crapemyrtle that has a low susceptibility.
Ignazio Graziosi: And for example, the species Lagerstroemia speciosa, they are studying these still, though.
Ignazio Graziosi: Okay, so those are the plants in Asia.
Ignazio Graziosi: What about the plants in North America?
Ignazio Graziosi: We know that it attacks basically most of the cultivar of the crapemyrtle, but unfortunately,
Ignazio Graziosi: like the EAB was able to find the white fringetree, the crapemyrtle bark scale started to
Ignazio Graziosi: feed happily on American beautyberry and also on St. John's wort.
Ignazio Graziosi: So, this can be a problem, of course, because it can go around attacking other plant.
Ignazio Graziosi: Okay, we are familiar with the disease triangle, so we may ask, okay, what about the role of
Ignazio Graziosi: the environment?
Ignazio Graziosi: What is the role of the environment here?
Ignazio Graziosi: Unfortunately, again, scales are one of the group of insects that most take advantage of urban heat island.
Ignazio Graziosi: Urban heat island, of course, is the phenomenon that causes temperature due to hardscape in the city to be even 10 degrees higher.
Ignazio Graziosi: And this has two effects.
Ignazio Graziosi: First of all, it stresses trees and they become more susceptible to pests.
Ignazio Graziosi: Second, it accelerates the development of the insect itself.
Ignazio Graziosi: And scales are very good in taking advantage of that.
Ignazio Graziosi: OK, let's go to some good news, the tools, the weapons we have to control it.
Ignazio Graziosi: So this is an overview, again, of the chemical control available for the crapemyrtle bark
Ignazio Graziosi: scale.
Ignazio Graziosi: We have soil drench, we have soil injection, we have foliar sprays, and also some soaps
Ignazio Graziosi: they can be used mostly to target crawlers, which again are the small, the young nymphs,
Ignazio Graziosi: like the one, the pinkish one in the photo here.
Ignazio Graziosi: Okay, you can see in the table different product brand names and how they can be applied.
Ignazio Graziosi: And I encourage you again to snatch that QR code because we'll give you the full protocol
Ignazio Graziosi: that you can use.
Ignazio Graziosi: The control, the chemical control is complicated by the fact that crapemyrtle is not good in
Ignazio Graziosi: absorbing systemic insecticide through trunk injection.
Ignazio Graziosi: The chemical moves very slowly, so that is not a viable option, unfortunately.
Ignazio Graziosi: Okay, we know about natural enemies, so we may ask now, looking at our map, what is the
Ignazio Graziosi: situation for this pest?
Ignazio Graziosi: Yes, in Asia, there is a healthy community of predators and parasitic wasps that worldwide
Ignazio Graziosi: and in Asia can attack.
Ignazio Graziosi: In the US, they were not able yet to clearly find an effective parasitoids, but there are
Ignazio Graziosi: many predators that can feed on the crapemyrtle bark scale, and they are used to try to control
Ignazio Graziosi: it.
Ignazio Graziosi: So, this is another question for you.
Ignazio Graziosi: If you know what is this, please write it in the chat box.
Ignazio Graziosi: Okay, so those are eggs of lady beetles, because lady beetles, different species of lady beetles,
Ignazio Graziosi: are avid, hungry predators of the crapemyrtle bark scale.
Ignazio Graziosi: There are three main species: the twice-stabbed lady beetle, the bigeminal, sorry,
Ignazio Graziosi: The bigeminal lady beetle, which looks like the twice-stabbed, but is a completely different species
Ignazio Graziosi: and also the non-native Harlequin lady beetle.
Ignazio Graziosi: These species, they will find trees infested with the crapemyrtle bark scale and they will feed on nymphs and adults alike.
Ignazio Graziosi: So, they help, yes, they do help, but often they arrive too late in the season and they
Ignazio Graziosi: are not specialists.
Ignazio Graziosi: They will feed on other prey, which means they will not stay for many generations on
Ignazio Graziosi: the tree, providing continuous control, and that is a problem.
Ignazio Graziosi: So this is my last question for you, if you have any idea of what is this.
Ignazio Graziosi: This of course is an egg from another predator that would happily feed on the crapemyrtle bark scale.
Ignazio Graziosi: It's called stalked egg.
Ignazio Graziosi: This is a beautiful egg of lacewings.
Ignazio Graziosi: One species in particular, the red-lipped, green lacewing, it feeds and predates on crapemyrtle
Ignazio Graziosi: bark scale nymphs and eggs as well.
Ignazio Graziosi: And you can see on the sequence on the right, this is a larvae of the lacewing, which are
Ignazio Graziosi: the most voracious.
Ignazio Graziosi: They swing. Do they work? Yes, they are actually available commercially, of course, to control
Ignazio Graziosi: different pests, including CMBS. But the problem is they don't build up a population on the
Ignazio Graziosi: plant like the previous case. And also adults need to feed on.
Ignazio Graziosi: sugar. And this means that you have to continuously, through the season, release.
Ignazio Graziosi: So, just one release at the beginning of the season is not enough.
Ignazio Graziosi: But they are commercially available and they can be used.
Ignazio Graziosi: Of course, you need to do chemical control very carefully because it has a potential to
Ignazio Graziosi: infuriate the biological control.
Ignazio Graziosi: At the same way as for the EAB, what we want in the future is a balance.
Ignazio Graziosi: We want the population of the scale low because the community of natural enemy is healthy,
Ignazio Graziosi: but we want to use and we want to do additional research to find effective chemical control
Ignazio Graziosi: that maybe is more compatible with the natural enemy.
Ignazio Graziosi: Okay, this brings me to the last, I would say, five, eight minutes, which is the last story in my presentation, which is a native tree impacted by native pests.
Ignazio Graziosi: And our example is the orange-striped oakworm moth.
Ignazio Graziosi: So this, of course, is a very well-known pest of oaks, especially red oaks in the group of the red
Ignazio Graziosi: oaks, but can feed on other plants, including hickory, birch, and maple. On the left,
Ignazio Graziosi: It's interesting because you can see that the skeletonizing damage is the one that is done by the baby larvae after hatching.
Ignazio Graziosi: And then as they grow, they start feeding on the entirety of the leaf lamina.
Ignazio Graziosi: And in some case, extreme case, especially for small trees, they can completely strip a tree.
Ignazio Graziosi: And this tree, the four on the right, is in early August.
Ignazio Graziosi: And it's a young, but not super young tree.
Ignazio Graziosi: It's a willow oak that was completely defoliated.
Ignazio Graziosi: OK, a little summary, I know a lot of you are already familiar with it, is of course
Ignazio Graziosi: a late summer and fall season pest that offers winter as a pupa and produces in the south
Ignazio Graziosi: two generations per year.
Ignazio Graziosi: So, we can start here.
Ignazio Graziosi: The adults they mate and the female lay eggs here on the underside of leaves in the late
Ignazio Graziosi: summer.
Ignazio Graziosi: And then young larvae, it initially feeds all together on the same branch where they
Ignazio Graziosi: hatched.
Ignazio Graziosi: And then as they grow, they disperse a little bit because they need a lot of leaves.
Ignazio Graziosi: And then again, they can defoliate. In some cases, they can defoliate completely a tree, but those cases are quite rare and exclusively for small trees. And at the end of the season,
Ignazio Graziosi: After, for example, for the south, the second generation is complete in the fall with the
Ignazio Graziosi: first cold, the larvae they drop to the ground and they will pupate in the first five inch
Ignazio Graziosi: in the ground.
Ignazio Graziosi: Okay, so we can use our map as a tool to ask questions.
Ignazio Graziosi: Okay, it's a native pest.
Ignazio Graziosi: Why it causes or can cause so much damage?
Ignazio Graziosi: What about the plant?
Ignazio Graziosi: What about the other factor we looked together earlier for the other two pests?
Ignazio Graziosi: First of all, of course, is a pest of particular relevance for urban and landscape trees and young trees.
Ignazio Graziosi: Why?
Ignazio Graziosi: Remembering this triangle.
Ignazio Graziosi: What is the role of the plant? This is an example.
Ignazio Graziosi: A lot of the trees in urban environment are trees that come from the nursery,
Ignazio Graziosi: and so are often clonal trees.
Ignazio Graziosi: The genetic variability of those trees are very low.
Ignazio Graziosi: For example,
Ignazio Graziosi: An example, on a UGA campus in Athens, there are a lot of beautiful Nuttall oaks.
Ignazio Graziosi: But those, they come from, they are very high quality trees, but they are basically the same tree.
Ignazio Graziosi: And so the susceptibility is low.
Ignazio Graziosi: One tree means the susceptibility for all the trees on campus of the...
Ignazio Graziosi: Nuttall oak is low.
Ignazio Graziosi: And so they are heavily attacked by the orange-striped oakworm moth.
Ignazio Graziosi: Okay, what about the environment?
Ignazio Graziosi: An example, again, yes, in urban environment, we have the problem of heat.
Ignazio Graziosi: Again, and we know that we'll stress trees, but we'll help the development of the orange-striped oakworm moth as well.
Ignazio Graziosi: These are some of the reasons why it can be a pest.
Ignazio Graziosi: Okay, what about natural enemies?
Ignazio Graziosi: So right now we know all the questions we should ask.
Ignazio Graziosi: Yes, there are natural enemies that are being described.
Ignazio Graziosi: We know of them.
Ignazio Graziosi: There are various predators that feed on larvae, for example, yellow jackets and other wasps.
Ignazio Graziosi: There are various parasitoids and fungal disease that kill the pupae up to 10 or in some case 20% of the pupae.
Ignazio Graziosi: And there are a lot of parasitoids that parasitize the eggs.
Ignazio Graziosi: And it's important, this is an example. On the picture on the left, this is the underside of
Ignazio Graziosi: pinnacle leaf full of eggs from the orange-striped
Ignazio Graziosi: oakworm moth. But if we look closely, we see that some of those eggs are yellow.
Ignazio Graziosi: Those eggs are empty eggs. You can see the opening here on the side. They open like a wallet.
Ignazio Graziosi: and the baby larvae already came out, so they hatched.
Ignazio Graziosi: But some other eggs, you can see this one, for example, the dark ones,
Ignazio Graziosi: they have circular openings. That means it has been parasitized.
Ignazio Graziosi: So that is a parasitoid, that is an egg parasitoid, a wasp that emerged from that egg.
Ignazio Graziosi: Okay, let's talk about control. So since this pest can be a pest but in some cases the damage is not so high,
Ignazio Graziosi: it's important to understand the need for the control.
Ignazio Graziosi: First of all, we need to distinguish between aesthetic damage and actual damage for the plant.
Ignazio Graziosi: The threshold is around 25% of defoliation. And then we need to assess the season.
Ignazio Graziosi: Why? Because late defoliation, even if it's a very substantial defoliation, but occurs late in the season, is not really harmful to the tree, because the tree already stores all the nutrients, and so it's not very harmful. So it's important to kind of judge.
Ignazio Graziosi: the severity of the situation.
Ignazio Graziosi: What can we use, though?
Ignazio Graziosi: So we can use Btk, Bacillus thuringiensis
Ignazio Graziosi: kurstaki, as a foliar spray,
Ignazio Graziosi: which is effective,
Ignazio Graziosi: but mostly on young instar, of course,
Ignazio Graziosi: on young larvae,
Ignazio Graziosi: has a very little impact on natural enemy,
Ignazio Graziosi: which is good,
Ignazio Graziosi: but often needs to be reapplied.
Ignazio Graziosi: But there are also other options for contact and also systemic insecticides.
Ignazio Graziosi: I encourage you also here to take a look at the publication link to the QR code here if
Ignazio Graziosi: you are interested.
Ignazio Graziosi: With that, I came to the end of my presentation.
Ignazio Graziosi: And I hope I will be able to provide you some insight on what are the biological parameters and the ecological interaction you have to look at to understand what is the damage and the control that can be applied to a pest.
Ignazio Graziosi: With that, I think I will stop my sharing and I will take any question you may have.
Ignazio Graziosi: And I will ask your help, Bodie, to summarize any question that came.
Bodie Pennisi: Thank you, Ignazio. That was great. Lots of really, really excellent information.
Bodie Pennisi: There hasn't been a question in the chat. There's lots of really good comments. Thank you.
Bodie Pennisi: I do want to mention something. When you were talking about the crapemyrtle bark scale,
Bodie Pennisi: unfortunately I have seen much expansion of the pest in landscapes, especially new landscapes, but even established
Bodie Pennisi: I
Bodie Pennisi: landscapes. I mean, I was in Savannah last year, same tree. At that height, there was no evidence.
Bodie Pennisi: I mean, again, the tree was pretty high. But this year, we were just there like two weeks ago,
Bodie Pennisi: and it was right there. And, you know, it was a large tree too. And all across the areas around
Bodie Pennisi: the planet, I have visited pretty much, I would say maybe about 60-70% of plantings have evidence.
Bodie Pennisi: So yeah, it's pretty bad.
Bodie Pennisi: Yeah, we just have lots of really happy people.
Bodie Pennisi: So thank you so much again.
Bodie Pennisi: I know you stayed late to entertain us
Bodie Pennisi: and share with us your expertise and knowledge.
Bodie Pennisi: So have fun, be safe,
Bodie Pennisi: and have a safe trip back to the U.S.
Ignazio Graziosi: Thank you, Bodie. It was my pleasure. I really enjoyed it. And yeah, I'm looking forward to being in touch.
Ignazio Graziosi: Thank you. Bye-bye.
Rich Braman: All right, everybody. Thanks for joining us again for the first one of these of this year.
Rich Braman: And we'll see everyone in March.
Rich Braman: And just make sure you get your sign-in sheets to us at gtbop at uga.edu.
Rich Braman: And if you need to mail those to us, you'll find that mailing address at the top of the sign-in sheet.
Rich Braman: I think that's it for me, Bodie.
Bodie Pennisi: Thank you, Richie.
Rich Braman: I'm going to hang around for just a minute to make sure we don't have any procedural questions, but I'll see you soon, buddy.
Bodie Pennisi: All righty.