Text Transcript with Description of Visuals
| Audio | Visual |
|---|---|
| Music plays | Title slide. Presentation title: Codling Moth Mating Disruption is 30+ years old! What Have We Learned? What Still Needs to Be Done?” Author information: Don Thompson, Pacific Biocontrol Corporation”. |
| Good morning everybody. Codling moth mating disruption is 30 years old. A tremendous amount of research has been done over the last 30 years, and I’d like to review some of the things we’ve learned and what still needs to be done. | Slide appears containing the title of the presentation along with an illustration of a codling moth with its wings spread. |
| I like to do this in a unique way: by comparing what is known about oriental fruit moth mating disruption which was first registered in 1986, and codling moth mating disruption, which was first registered in 1991. | Slide titled “Compare Mating Disruption Systems” contains two orchard photos side by side. The first image is labeled 1986 and a photo of an oriental fruit moth sits below it, indicating that oriental fruit moth mating disruption was first registered in 1986. The second image is labeled 1991 and has a codling moth below it as codling moth mating disruption was first registered in that year. |
| The efficacy of oriental fruit moth mating disruption is quite robust, most people would give it a 10 out of 10. Codling moth mating disruption is more variable. So I’d like to discuss, why the difference between the two systems? | Slide titled “Efficacy of Mating Disruption: contains photos of both an oriental fruit moth and a codling moth along with their scientific names. Below each image is a cartoon graphic of three judges holding up score card. The oriental fruit moth has three ten ratings, while the codling moth has an 8, a 6, and a 10. |
| So first we really need to understand the physiological and behavioral responses of each insect to their pheromone. | A transition slide titled “Need to understand physiological and behavioral responses” with small supporting images of insect anatomy and research activities. |
| So let’s start with the physiological responses. You can see the scan here of a codling moth. You can see the antenna here, and on the antenna are all these hair-like structures called sensilla. And here is one sensilla or sensillum, and you can see this opening here on the side of the sensillum where the pheromone molecule will move into the inside of the sensillum. | Slide titled “Physiological Responses” contains a close up microscope image of a codling moth’s head, highlighting antennae and sensory structures. Additional images on the right include magnified sensilla and a diagram of a single sensillum indicating where pheromone detection occurs. |
| If you look at that more detail, here’s the pheromone, the black dot that moves through this opening in the sensillum, down these pore tubules, and then into the sensillum lymph where it’s met by binding proteins. And these binding proteins attach to the pheromone molecules and then move them to these receptors on the outer dendrite. When the number of pheromone molecules on their receptors gets to a point, it exceeds a threshold and the signal is sent from the outer dendrite down to the inner dendrite to the olfactory receptor neuron and down the axon. | Slide titled “Physiology of Pheromone Perception” shows a labeled drawing of a moth antenna and its sensory hairs. Two diagrams to the right illustrate pheromone molecules entering a pore in the sensillum and binding to receptors on the outer dendrite of sensory neurons. The diagrams below shows a signal being sent from the outer dendrite to the inner dendrite and then to the olfactory receptor neuron and the axon. |
| And then the axons sends the signal down the antenna, into the antenna lobe where further processing occurs. | Slide titled “Physiology of Pheromone Perception” shows a labeled diagram of insect antennal structures, illustrating how the signal is sent from the axons to the antennal lobe for processing. |
| So just to summarize that then, you have the sensilla on the outside of the antenna. Some are specific to pheromones, some are specific to plant volatiles, both send signals down into the antenna lobe. Processing for pheromones is done differently than for the plant volatiles, but there is an integration of the signal, and an output to the brain of the insect. Once the brain receives those signals, then it elicits a certain behavior. | An additional diagram appears on the slid comparing plant volatile sensilla and pheromone specific sensilla on the moth antenna, showing how each connects to a different group of glomeruli which sends signals to the brain. |
| And with behavioral responses to codling moth pheromone, the insect is perceiving the pheromone. The males are perceiving the pheromone downwind and they’re moving upwind following a concentration gradient until they get to the female. This is quite a remarkable process given that the female shown here is emitting pheromone at five nanograms per hour. It’s quite amazing when you think about a drop of water is 0.05 grams and this is a very small amount of pheromone on an hourly basis. But the males through the canopy that are able to follow these plumes find the female then mate with her. You can see that in this lower part of the graph here’s an electropiso sprayer. It vibrates at very high intensity and sends a pheromone signal and the males follow upwind in pursuit of it. | Slide titled “Behavioral Responses to Odor Plumes” showing moth flight paths as they move through an odor plume, generated by an electropiso sprayer, until they reach the female. |
| OFM mating disruption has been working very well for the last 35 years. Why is that? What is it about mating disruption for OFM that makes it so robust? | Transition slide titled “OFM MD Working Well – 35 Years!”, with a large image of an oriental fruit moth with it’s wings spread. |
| So I went back and I looked at some old papers. This one from Tom Baker and Wendell Roelofs in 1981, and it’s entitled “sex pheromone dosage and blend specificity of response by OFM males” and there’s just a couple of points that I’d like to bring from this paper. Males exhibited sustained upwind flight only to intermediate concentrations of pheromone. | Slide titled “Behavioral Responses” contains the title and author information of the mentioned research paper. Text below this highlights the response of males to intermediate concentrations of pheromone. |
| High concentrations of pheromone caused arrestment some distance from the source. | Additional text appears on screen highlighting the response of males to high concentrations of pheromone. |
| So Tom Baker and Wendell Roelofs did another experiment in the field and published this: initiation and termination of oriental fruit moth male response to pheromone concentrations in the field”. And simply, they conducted the experiment in this way: they had concentric rings at known distances from the center. And in the center, they had pheromone lures loaded with either 10 micrograms or a thousand micrograms of pheromone. So they knew the distance from each one of these rings, and then they released male OFM downwind from these sources of pheromone. And they wanted to follow the flight activation and the upwind flight to these different concentrations of pheromone. | Slide titled “Behavioral Responses” contains the title and author information of the mentioned research paper. A diagram below this outlines the experimental setup, with pheromone lures of 10 or 1,000 micrograms of pheromone set up downwind, and codling moth males flying upwind to reach them. |
| And what they found is that, depending on the lure dose 10 micrograms and a thousand micrograms, first of all notice that both the OFM males were activating flight, taking flight to both concentrations, low-dose and a high dose. But when you were one meter from the source, from the pheromone lures, the OFM males kept on flying. Whereas to the higher dose, 1000 micrograms, 56 percent of those males stopped flying. The dose was too high just before the source of pheromone, before these lures. 12 percent at the low dose stopped, didn’t make it. But a hundred percent of the males stopped flying towards the higher dose. In other words, they found this upper threshold for active space. | Slide summarizes the results of the mentioned study on oriental fruit moth response to pheromone concentrations, showing that higher lure doses increased flight termination before reaching the source, indicating an upper threshold for active pheromone tracking. |
| So what is the active space? The active space is the concentration of pheromone that enables a successful response. So a successful response being males down here are detecting the pheromone coming from the female, are able to follow a concentration gradient up to the female, where they land and mate with that female. That’s the active space. There’s a lower concentration and an upper concentration that enables that successful response. | Slide titled “What is Active Space?” which contains an illustration of male codling moths following a pheromone trail towards a female. Text on screen stresses that there is a lower and upper pheromone concentration threshold. |
| So if the concentration is above the upper threshold of the active space, then it overwhelms the sensory system. So if now the pheromone is coming from a hand applied dispenser, massive concentration of pheromone moving downwind. Yes, the males might still initiate flight down here and start flying on, but they get arrested just like Tom Baker and his colleagues said. They stopped flying because the concentration is too high. So with respect to mating disruption, we call that non-competitive mating disruption. | Slide titled “Concentration above upper threshold of active space” contains an illustration of male moths initiating flight towards a pheromone trail that is above the upper threshold of active space and arresting the flight as the pheromone level overwhelms their sensory system. Text on screen states that this is non-competitive mating disruption. |
| If the concentration is below the upper threshold of the active space, then the sensory system is not overwhelmed. So again looking at it, flight is initiated and they fly upwind but the concentration is not greater than the upper threshold. It’s less, so they keep on flying towards those dispensers. We refer to this as competitive mating disruption. | Slide titled “Concentration below upper threshold of active space” contains an illustration of male moths initiation flight towards a pheromone trail that is below the upper threshold of active space. Their flight is not arrested and the sensory system is not overwhelmed. Text on screen states that this is competitive mating disruption. |
| So just to kind of quickly show a summary of this, here’s your OFM female calling, and you have hand applied dispensers releasing high doses of pheromone. The males are flying upwind but they get above that active threshold of the active space and they stop flying and cannot proceed further. Whereas with codling moth, again the females are calling. You’ve got hand applied dispensers releasing pheromone. The males follow up that plume towards either the dispensers, they do not get overwhelmed and we call this competitive attraction. | Two cartoon graphics appear. The top graphic is labeled “non-competitive attraction” and shows male oriental fruit moths initiating flight towards a female in a tree which contains mating disruption dispensers. They suspend their flight as the pheromone level is above the threshold of active space. The bottom image shows male codling moths in the same situation but the pheromone level is below the upper threshold of active space. Their flight is not arrested and they are attracted to the dispensers |
| So going back to OFM, this paper was published by Mike Reinke and his colleagues at Michigan State University in 2014 called “pheromone release rate determines whether sexual communication of oriental fruit moth is disrupted competitively or non-competitively”. | The title and author information of the mentioned research paper appears on screen. |
| So what they concluded was that OFM has disrupted competitively with female equivalent pheromone dispensers. Like you see, here is the lure. So you put 400 of these out. The release rate coming off those lures is more equivalent to a female OFM. So if you have 400 of these per acre then OFM has disrupted competitively, because the males are flying to them. But if you put high releasing dispensers, hand applied dispensers though, then they’re disrupted non-competitively with these dispensers. They’re getting arrested in flight. They’re not able to complete the location. | Slide summarizes the results of the mentioned study showing that pheromone release rates determine whether mating is disrupted competitively with equivalent dispensers or non-competitively using high release dispensers. |
| So non-competitive mating disruption, just to summarize, flight is initiated, they fly upwind and the concentration gets too high because they’re coming from a pheromone dispenser. It overwhelms their sensory system and they get arrested. They stop flying. | Slide titled “Non-competitive Mating Disruption” contains an illustration of male moths initiating flight towards a pheromone trail that is above the upper threshold of active space and arresting the flight as the pheromone level overwhelms their sensory system. |
| So what does this mean for you as growers? Well if you were to walk into an orchard, your stone fruit orchard, you really need to think about: “okay it’s going to be non-competitive”. So what you want is a uniform, even distribution of high release dispensers that last all season long, because if you get a uniform distribution of these high release dispensers, you’re going to have a concentration of pheromone that is high enough everywhere in the orchard to disrupt those insects, those OFM males non-competitively. | Slide titled “What Does this Mean for You?” contains an image of an apple orchard along with text highlighting the need for even distribution of high release dispensers and that dispensers must release all season long. |
| So you could see that in this graph here, control is density independent, and I’ll show you this in a second. So here you see on the y-axis, you can see percent catch, 100 percent catch down to zero. And as you put out the number of dispensers here, you can see you get to the point where you have enough dispensers out there that fill the entire orchard with enough pheromone at a high enough concentration so that the upper threshold of the active space is reached, and you shut down male flight. They get arrested. | Slide titled “Non-competitive mating disruption” presents a graph showing moth catch decreasing as the number of pheromone dispensers increases. Text on screen stresses that control is density independent. |
| So if you look at this chart, let’s say it’s a 10 acre orchard. Each one of these red dots represents a pheromone dispenser. The blue dots would represent concentrations or density of OFM insects in that orchard. You can see high populations here and low populations over here. Well with OFM mating disruption, because it’s non-competitive, it’s more density independent. So as long as you have a concentration or an application of enough high releasing dispensers, you can get good uniform concentration and shutdown of OFM mating. | Slide titled “OFM Mating Disruption” contains a schematic illustrating non-competitive, density independent mating disruption in oriental fruit moth, where high release pheromone dispensers create a uniform pheromone concentration across the orchard, preventing mating. |
| What about codling moth mating disruption? As I said at the beginning, it’s working okay after 30 years, but it’s not a 10 out of 10 all the time. | Transition slide titled “CM MD Working Okay – 30 Years” containing a large drawing of a codling moth adult with it’s wings spread. |
| Why not? So what’s been observed in the field? Peter Witzgall in Sweden has done a lot of behavioral work where he’s looking at a response of codling moth males in orchards treated with pheromone dispensers. Remember these dispensers have a release rates about a thousand times greater than what a codling moth female releases. | Slide titled “What’s Been Observed?” contains a photo of an apple orchard. A graphic of mating disruption dispensers attracting male codling moths is overlayed. |
| So over two or three year period, Peter and his colleagues actually sat out in orchards watching the behavior of codling moth male and female insects in response to the treatment with pheromone dispensers. And they became so good at this that they were able to differentiate male and female codling moth from each other. He concluded that codling moth mating disruption treatment turns on codling moth search engine. It causes them to fly and search for sources. | The title and author information of the mentioned research paper appears on screen along with a photo of the researcher and an example flight path of a moth through the orchard. |
| Gary Judd and his colleagues at Summerlin British Columbia published this paper in 2005 called “the behavioral response and attraction of codling moth males to their pheromone following various pre-exposures”. So what Gary wanted to find out is, if you treated an orchard with pheromone dispensers and place codling moths in there, they would have a certain exposure to whatever background concentration was created in the orchard. And they wanted to see how that impacted their behavior in wind tunnels in laboratory situations. | The title and author information of the mentioned research paper appear on screen along with photos of a mating disruption dispenser in an apple orchard and a wind tunnel in a laboratory. |
| So what Gary did is he first of all applied pheromone dispensers to these orchards, and then he took codling moth males and he put them into bags and hung those bags into the trees. So whatever concentration was created by these pheromone dispensers is what the exposure was to these males in the bags. And he did this and left them there for 24 hours, and then took the bags, and then took them back to the lab, and wanted to see whether or not after this exposure whether males would actually fly up to a pheromone source; a lure or a female. And sure enough those codling moths still flew to that source. | Slide summarizing the results of the mentioned study which contains an illustration of the male codling moths in bags attached to trees in the pre-exposed orchard. Additionally there is a photo of a wind tunnel with a codling moth inside of it. Text on screen highlight that the codling moths still flew to the source when they had been exposed to pheromone dispensers. |
| So Gary then wanted to know what would it take? What kind of exposure would it take to codling moth pheromone in order to shut it down? So he took codling moth males and put them in these mason jars with known concentrations of pheromone and sealed and left them there. And he determined that it would take 30 minutes of exposure to concentrations of about 35 micrograms of codlemone per liter of air in order to eliminate their upwind flight to a pheromone source, or to affect the sensilla on the antenna so that the sensilla was no longer send signals down to the brain of the insect. A lot of pheromone over quite a period of time before codling moth would be shut down. | Slide titled “Exposure to 35 micrograms of Codlemone/Liter” summarizes the results of the mentioned experiment. Supporting images show codling moths in mason jars, a microscopy image of the sensilla of the antennae, and an image of a codling moth in a wind tunnel. |
| So in light of Gary’s results from the previous slide, let’s look at some release rate comparisons. So on the slide we’ve got a logarithmic scale going from 10 up to 100 million nanograms, and so this is the pheromone emission rates. So we start with the female that releases five nanograms per hour. So way at the bottom of the scale and, like I said, a hand apply dispenser’s releasing roughly a thousand times more. So 5,510 nanograms per hour. And then Gary’s mason jar where he determined there was 35 000 nanograms per hour that it would take in order to shut down codling moth responses to pheromone. And then up here 32 million nanograms per hour that come out of a pheromone emitter. So that gives you a relative comparison. | Slide titled “Release Rate Comparisons” contains a comparative scale showing pheromone emission rates across different dispenser typers, illustrating a logarithmic increase from low natural emissions to very high-release mating disruption devices. |
| So with those release rate comparisons in mind, let’s look at another couple of experiments conducted by Peter McGee for his PhD at Michigan State University. He wanted to look at how high exposure increased flight and trap catch. I’ll show you two slides one with aerosols and one with hand apply dispensers. So with aerosols you had three treatments: you had four 10 acre blocks treated with nothing, no pheromone, four ten acre blocks treated with aerosol emitters at one per acre, these blocks here were also treated with emitters at one per acre. What he did is he took bags and he put 800 codling moths onto branches and covered them up with bags in each one of these treatments. The only difference is on this treatment here, the blue bar you can see, he sprayed with aerosol five times onto the leaves before he put the codling moths and the bags over the branch. So this was treated with a lot of pheromone. This was just the background concentration of pheromone from the one meter per acre and no pheromone. He then took those bags off the branches and took those codling moths to an untreated orchard. So no pheromone exposure at all, and released them and wanted to see what those exposures did to flight and trap catch. And lo and behold, what you see is that those blocks where they had treated with five sprays directly onto the foliage, they became super searchers. Those flew the most and got the most trap captures in these other orchards. | Slide titled “High Exposure Increase Flight and Catch” contains a bar chart showing mean codling moth catch per replicate across treatments. Moth catch is highest with repeated pheromone aerosol exposure, intermediate with a single exposure, and lowest in the no pheromone control. Indicating increased flight and trap catch following high pheromone exposure. |
| He also did the same thing with hand applied dispensers. So the same basic protocol. So we had four 10 acre blocks each treated with hand applied dispensers in this gray bar and in the yellow bar. And then the blue bar is 410 acre blocks untreated. And again he put bags over branches with 800 codling moths in each of these treatments, in the no pheromone and the 400 per acre. And in this one, the only thing he did differently is he put two hand applied dispensers inside those bags. So lots of exposure coming from those. He took all the bags out and then released the codling moths into untreated orchards to see what the pheromone exposure would do to flight and trap capture. And you can see once again that the exposure to higher concentrations of pheromone stimulated flight and searching behavior and trap catches. | Slide titled “High Exposure Increase Flight and Catch” contains a bar chart showing mean codling moth catch per replicate across treatments. Moth catch is highest in the treatment where dispensers were placed inside the bag, intermediate in the treatment with hand applied dispensers in the orchard, and lowest in the no pheromone control, again indicating increased flight and trap capture following high pheromone exposure. |
| So this again is an example of competitive attraction. Exposure to high concentrations of pheromone, whether it be hand applied or aerosol sprays, stimulated that flight and searching behavior. They become super searchers, they move up towards sources of pheromone. | An illustration titled “Competitive attraction” appears showing male codling moths being attracted to pheromone trails given off by hand applied mating disruption dispensers. |
| So what does this mean for you? First of all, dispensers compete with males, okay? And so because of that competition between dispensers and males for the attention of the females, then you need to know where all your hot spots are. Therefore pheromone trapping is incredibly important to you. By knowing where your hot spots are or where your low population sites are, then you can adjust dispenser density and supplemental control. | Transition slide titled “What does this mean for you?” contains a photo of an orchard and a bullet point list highlights key reminders for competitive control. |
| Codling moth mating disruption is competitive, therefore control is density dependent. You can see on this graph here from Larry Gut and Peter McGhee and Jim Miller, you’ve got trap suppression here on the y-axis and the number of dispensers on the x-axis. So we have zero dispensers, you get this catch up here close to 100 percent catch. And as you add even a few dispensers, you can see even with minimum amount, maybe five or ten dispensers in these plots, you reduce trap a catch by about 75 percent. And as you add more dispensers, you improve the efficacy of mating disruption of trap suppression so it operates by a competitive attraction. | Slide titled “Competitive Mating Disruption” contains a line graph illustrating competitive attraction. On the x-axis is the number of dispensers, on the y-axis is the percentage of catch. The percentage of trap catch is show to go down as a result of more dispensers being added. An overlay on the graph show that this is an example of a moth population with few females. |
| But as you get into higher populations, you can see many more females out there. Same number of dispensers and all of a sudden the competition goes up. | The same graph is shown but the overlay shows four female codling moths rather than one. |
| So what that means is, codling moth’s main disruption is competitive attraction, density dependent. So on this graphic here from Vince Jones and Mike Doerr, the red dots represent pheromone dispensers and the blue dots represent populations of codling moth. Larger blue dots represent higher populations, small blue dots represent small populations. And you can see over here where this arrow is, you’ve got like 20 codling moths that were found in this location, and you’ve got really the same number of dispensers out here as you do over here on the right hand side where you’ve only found one codling moth. So you’ve got one codling moth, low population pressure and you’ve got the same number of dispensers. So you got to remember that the dispenser density relative to codling moth population is really important. The more traps the better. You need to know where your hot spots are, where your low populations are. You need to trap with as many traps as you can manage. | Slide titled “Codling Moth Mating Disruption” contains a schematic illustrating competitive mating disruption in codling moth which is density dependent, where high release pheromone dispensers create a uniform pheromone concentration across the orchard, but codling moth populations are shown to have very different densities across the field. Text highlight that dispenser density is relative to codling moth population. |
| Point sources are extremely important. Regardless of what formulation you’re using, two to four hundred dispensers to the acre is really important for control of codling moth. | Transition slide titled “Point Sources Important” contains an illustration of trees with hand applied mating disruption dispensers tied to them. Below this is text outlining that 200 to 400 dispensers per acre is the correct amount. |
| Why not increase the release rate and reduce the number of point sources? Larry Gut did this experiment about 20 years ago, not long after biocontrol came out with a dispenser called isomite CTT. And we had thought that labor was being an issue, therefore why not put twice as much pheromone in a dispenser but reduce the number of point sources that you have to place per acre? So Larry compared the 200 of the isomate CTT with 200 isomates C plus and 400 isomate C plus, relative to a no pheromone control. | Slide titled “Why not increase release rate and decrease points” contains the experimental design as outlined in the audio, a list of the four treatments used, and a photo of an apple orchard. |
| And so here’s the release rates, so the blue bars represent the release rate coming off on isomate CTT applied at 200 dispensers. The gray bars represent the amount of pheromone coming off of isomate C plus dispenser applied at 400 to the acre. You can see CTT has a higher release rate therefore the logic being then you could put out less point sources per acre. What did Larry find? Well he did fruit injury at harvest. The full rate of C+ was the best of all of those pheromone treatments so here’s 400 C+ and 200 of the CTT and you can see the 200 C+ worked almost as well or a little bit better than 200 CTT. | Slide titled “Fruit Injury at Harvest” contains a bar graph of the mean percentage of fruit injury for the four treatments of the study. It is clear that all three treatments showed a large improvement when compared to the no pheromone control, with the 400 C plus treatment showing the least fruit injury. We see that the 200 C plus treatment, while similar to the 200 CTT treatment in results, showed slightly less fruit injury than the 200 CTT. |
| What that means is that increasing the release rate from a dispenser, putting more pheromone in there does not compensate for putting out less point sources per acre. | Transition slide titled “Increasing Release Rate” contains an illustration of trees with hand applied mating disruption dispensers tied to them. Below this is text outlining that increasing release rate does not compensate for less points. |
| Let’s look at another experiment conducted by Larry Gut at Michigan State University looking at the application rate number of point sources versus population size. So in a high population situation, Gary went back and looked at CTT at 50 per acre, CT at 100 per acre, CTT at 200 per acre. And again like we showed in those previous slides, a 400 C plus with the extra point sources is better. | Slide titled “Application Rate vs Population Size” contains a bar graph of the four application rates tested in the study versus the size of the codling moth population. As the application rates go up, the population sizes go down. |
| But what happens when you get into areas of your orchard or your entire orchard where your population density is low and that’s been determined by using extensive use of pheromone traps and history of that block? So what about the dispenser density relative to a lower cutting moth population density? | Slide titled “Codling Moth Mating Disruption” contains a schematic illustrating competitive attraction which is density dependent. We can see pheromone dispensers, shown as red dots, creating a uniform pheromone concentration across the block, but the codling moth populations, shown as blue dots, are very few in number. Text below this highlights that dispenser density is relative to codling moth population density. |
| And Larry showed this, that under low populations, all of a sudden the discrepancy between the different application rates of the different dispenser gets minimized. In other words, 200 CTT per acre is not that different from 400 C plus per acre at a low population density. And as you saw from Larry’s previous experiment, 200 of C plus would work as well as 200 CTT but at half the price of 400 dispensers to the acre. And as a result, biocontrol registered CM flux which goes out 200 to 400 dispensers per acre because of this data. | Slide titled “Application Rate vs Population Density” contains a bar graph of population size versus the 4 application rate treatments from the study, however the populations are very low across all treatments. |
| So the take-home messages from this part of my talk: OFM mating disruption works by non-competitive attraction. codling moth mating disruption works by competitive attraction. The efficacy of mating disruption is density dependent. codling moth has this aggregate of distribution, we know them as hot spots, so monitoring populations with pheromone traps and visual inspections of orchard is most critical, the most critical thing you can do. And the application of point source is of critical importance with the idea relative to the population density in your orchard. | Slide titled “Take Home Messages” contains a bullet point list of key messages as outlined in the audio. |
| For the last part of my talk, I’d like to talk about aerosol formulations. Currently there are four formulations available to you in Washington state: the puffer CM, the CM Mist, smart release CM, and the semio system. | Slide titled “Aerosol Formulations” contains photos of the 4 types of aerosol systems available. Each appears as an aerosol can with a sprayer mechanism on top. |
| What does the distribution of pheromone from an aerosol look like relative to what the distribution from a hand applied dispenser would look like? First of all these are Excel files used by Rufus Isaacs and MSU to illustrate what 400 dispensers per acre might look like. So each one of these points represents the placement of a dispenser and you can see the even kind of distribution of pheromone release coming from those dispensers. With an aerosol though, you only go one or two per acre but it’s a vast amount more pheromone being released from each aerosol emission than from hand applied, and that’s represented by the much larger peaks, but only two per acre. | Slide titled “What does distribution look like” contains a comparison of pheromone distribution patterns showing that hand applied dispensers create many small evenly spaced peaks, while aerosol application produced fewer, larger concentration peaks with broader coverage. |
| So how does pheromone then get released from an aerosol and cover such an area? Well what happens with an aerosol is that you take your pheromone, and you mix it with some sort of solvent to keep it in solution, and you place it into the can, and then the gas propellant is injected into the can, and these propellant gases have a very low boiling point. So some of them are have like minus 15 degrees Fahrenheit boiling point, so they’re all put into the can and so every time the emission is released you get this blast. The propellant and pheromone and solvent into the air, and it’s like an explosion. And it breaks up the pheromone particles and the solvents into very small particles. 30 to 120 microns in size and these small particles, just like spray drift, can move a long ways. | Slide titled “Pheromone Release from Aerosol” contains a photo of an aerosol can spraying a fine mist into the air. |
| This is a chart from Stephen Welter at the University of California. It talks about the movement of pheromones from aerosols. And so what he did is he put an aerosol unit here, and the unit was turned off. And then he had traps downwind, and he was measuring the percent trap suppression. And you can see, he’s only five percent suppression and 25 percent of suppression. The traps are all catching downwind and then he turns the unit on here, and with the wind behind now all of a sudden with the pheromone being released from this emitter, you’re getting 90, 95, 75 percent trap suppression. Quite a bit more than what you saw on when the unit was turned off. So that pheromone is moving both longitudinally and laterally a great distance from the source of emission. | Two maps compare pheromone movement and trap suppression with an aerosol unit on versus off. When the aerosol unit is off, trap suppression is limited and localized. When the aerosol unit is on, pheromone spreads downwind, producing broader and stronger trap suppression across a larger area |
| What about the mode of action of aerosols and how does that compare with the mode of action of hand applied dispensers? Peter McGhee did his PhD at Michigan State under Larry Gut looking at how males respond to the pheromone coming from aerosols, and he determined that male move upwind towards an emitter. So here’s the large plume coming from the emitter, and males are falling up along the edges of these plumes and then accumulating in behind the emitters, leaving females only downwind. So without the males, no mating. Again he determined the mode of action being displacement males being displaced from this area, therefore no mating occurs. | Slide titled “Mode of Action – Aerosols” contains a diagram showing male moths moving upwind towards aerosol pheromone sources, bypassing both traps and females, and reducing successful mating. |
| So competitive attraction or competitive mating disruption is very similar with aerosols and hand applied. The concentration of pheromone is insufficient to impact their sensory system, so the flight is not arrested. So the males move up towards an aerosol emitter and they’re accumulating in behind, leaving females downwind of the emitters with no males in the area, therefore no mating. so the high emissions from these aerosol emitters do not overwhelm the sensory system they still can fly. | A diagram illustrates competitive mating disruption, where the pheromone concentrations are insufficient to overwhelm the male moth sensory system, allowing normal flight behavior. |
| Because of that then, point sources are important too with competitive attraction. Here is more data from Peter’s PhD work. So we’ve got, in terms of percent trap shutdown here, you got zero emitters, so you got zero percent trap shut down. One emitter every four acres gives you pretty close to fifty percent trap shutdown. One every two acres, 77 percent. One per acre, two per acre, or three per acre, four per acre. You can see you get the same sort of curve as you add more and more emitters, and it’s not unlike that same curve that I showed you for hand applied. It’s just shown inversely, point sources are important too because competitive attraction is how aerosols are working. And Peter determined that to get the same efficacy of 400 expenses per acre, you would need about two emitters per acre. This was done in 10 acre blocks, mind you, so keep that in mind. When you work at hundred acre or a thousand acre blocks, emitters will work better. But in his experiment, 10 acre blocks, it took about two units per acre to equal 400 dispensers of hand applied. | A line graph shows that increasing the density of point-source pheromone dispensers leads to higher trap shutdown, demonstrating that competitive attraction increases as more point sources are added. |
| So there’s just one more experiment that came out of Peter McGhee’s PhD thesis research, and that is dealing with number of emissions from aerosol matters. And Peter looked at both the trap captures of sterile insects and wild insects relative to the number of emissions per hour coming from emitters. And you can see here, whether he sprayed once an hour, twice an hour, or four times an hour, it was really no statistical difference in terms of shutting down the trap captures, both with sterile and with wilds. But as soon as you turned off the emitters, then catches went up accordingly. So it’s really important to have those aerosol emitters emitting pheromone all the time. Turning them off can result in problems. So you can say, well we’re between flights, I’m not catching anything in my traps. But your traps, the resolution is not to the point where you can be absolutely confident there’s no codling moth activity out there. So having aerosol emissions occurring throughout the flight period of codling moth is really important. | A bar graph titled “MIST Emissions” shows the mean sum of male codling moth captures based on the 4 treatments mentioned in the study for both sterile and wild insects. It shows no statistical difference between treatments except for the sterile insects when the emitters are turned off. The number of captures for this treatment is significantly higher. |
| Beware the windward border with aerosol emitters. Again, you’re putting them out along the borders and there’s large gaps. Insects tend to move towards the edges anyway, so if you have gaps then you can have areas where the female is calling and the males are mating with them. So border sprays and hand applied dispensers along the edges are really important. | Diagram showing codling moths mating along the edge of a field, illustrating why additional border sprays or dispensers are needed to prevent mating. |
| So which dispensing system is better? I think that both can work and both can fail. It’s all about how you manage the system relative to the kinds of populations and densities that you have. So hand applied I think is probably more robust because you’ve got a uniform distribution of dispensers that just release from the time they’re put out until they’re empty. And so you want dispensers that go at least 180, 200 days of emission to get your full season protection. Aerosols can work fine too, but again you do have the issue of more gaps along the borders, and always treating larger areas is incredibly important to the efficacy of aerosols. | Slide titled “Which dispensing system is better?” contains a comparison of pheromone distribution patterns showing that hand applied dispensers create many small evenly spaced peaks, while aerosol application produced fewer, larger concentration peaks with broader coverage. Text below this stresses that both systems can work or fail, and that hand applied is more robust due to point sources. |
| So the take-home message from this part of my talk is aerosols release particles 30 to 120 microns in size, therefore pheromone coverage is extensive, they move a long ways. Aerosols work by competitive attraction, just like hand applied dispensers do. Therefore point sources are important too. Border areas can have gaps due to separation. | Slide titled “Take Home Messages” contains a bullet point list of key messages as outlined in the audio. |
| I’d like to end by just going back to what I was talking about at the beginning: Why are the responses to pheromone between OFM and codling moth so different? OFM high concentrations arrest flights. 100 to 200 dispensers to the acre is what you need. As long as you have a uniform concentration from those dispensers, you can arrest flight and get good control. Whereas high concentrations of pheromone from dispensing devices stimulates flight so codling moth continued to fly looking for sources of pheromone. | Slide titled “Why are the responses to pheromones so different?” contains photos of an oriental fruit moth and a codling moth along with their scientific names and the differences in their responses to pheromones. |
| Unfortunately we’re still missing the link between the basic and applied research we need to understand this question and the differences. And unfortunately we’ve lost so many researchers over the last 10 years or so. It’s hard to get this work done. | Slide titled “Where have all the researchers gone?” contains a photo of men in suits walking away from the camera. |
| As a result of that, we have to fall back on what we know works, the success of a systems approach. So I look at the mating disruption being the foundation the brick wall in which the system is built on, and by knowing the modes of action which I discussed today: population density and point sources and how one relates to the other. Then you can put together a systems approach which is sanitation, banding, rouging off infested fruit, use of insecticides, proper timing to reduce the populations, and then now sterile release is becoming important. But really central to it all is the use of traps. Having enough traps out there so you know where your hot spots are, you know where your low populations are. Therefore you can adjust your management approach according to what you find in your orchard. | Slide titled “Success of a Systems Approach” contains a diagram of integrated pest management systems for codling moth, with mating disruption as the foundation and sanitation, insecticides, sterile insect release, and traps acting together to protect apples |
| In finishing, I’d like to dedicate this presentation to the memory of Larry. Larry passed away in September of 2021, he began his career in Washington state with Jay Brunner in 1991 and he dedicated the next 30 years to understanding behavior modes of action of both OFM and codling moth. He made so many substantial contributions to our knowledge and really helped us implement these important technologies. Larry, you will be missed. | A dedication slide containing a black and white photo of Larry Gut and the text “You Will Be Missed.” |
| And with that, thanks for listening. | Thank you for listening slide. |
| Music plays | Credits for talk and video roll. |
