Here's the problem with the current theory of insect olfaction | Part 1 of 4

Well, hi friends. Welcome everyone. We're really excited to have you here for this webinar with the awesome Tom Dykstra, the one and only, the indomitable. I could think of a bunch of other adjectives, but I'm just going to stop there while I'm on the safe side in safe territory, because Tom is going to be doing most of the speaking today, not me, and so I better keep it low key. So thank you all for being here. Tom is a good friend of mine, has been for well over a decade, probably a decade and a half at this point, and I've been honored to know his work. We've had Tom here on our webinar series a couple of times in the past. A couple of clips that we've posted on YouTube which have been tremendously popular, where he talks about some of the interactions with insects and plants. And one of the this is the first webinar that Tom is going to be doing for all of us in a series of four where he will be talking about how insects really, truly perceive their environment. How it actually happens versus how mainstream science today thinks it happens. And you know what that means is when you think about offering a and improvement on existing knowledge. There is this question that I've been asked about other people who have been my mentors. It's been asked about Don Huber and others who've said that, well, if these people have all this great information, why has it not been published and why has it not been peer reviewed? And one of my friends made a comment that really stuck with me. He said that there are some people who have no peers. And that is true anytime you have a pioneer. The definition of a pioneer is that they have no peers. There is no one alongside of them that is helping them with their work and moving forward. And when I say there is no one, there is not, the collective industry is not moving with them. That's the very definition of a pioneer. So Tom is one of these pioneering people who have looked at insects, an insect olfaction, how insects perceive their environment from a completely fresh perspective and said, wait a minute, do we really understand what's actually happening and what's actually going on here? So my suggestion for you would be in this presentation, buckle in your seat belts and hang onto your hats because Tom has an extraordinary information with a lot of really great, extraordinary webinar presentation with a lot of really great information that you're really going to enjoy. And if you have any questions, we're going to have time for Q and A At the end, you're welcome to chat with each other and also type any questions that you have into the Q and A box. If there's anything that I can answer and respond to while Tom is doing his awesome presentation, I may do that. But also we'll have lots of time for Q and A in the end. So thank you all for being here. And Tom, turn it over to you.

All right. Thank you so much, John. I would like to thank aea. I've been an industrial entomologist for a quarter of a century. I have not been allowed to publish. I know there have been a lot of comments. Yes, you talk about publishing this and publishing that. That is indeed how academia works. I do not publish. I have not published. I'm not allowed to publish. I would have gotten fired if I published. But there is a massive amount of information that I have been able to accumulate, and AEA has been wonderful in allowing me to get up and give a few presentations. This is going to be a series of one of the four presentations that I have, an insect olfaction, which will. Even those four will just be introducing the issue for those who wish to go a little bit further. And there are a lot of things that can be learned by understanding how insects smell. There are ties in with the Brix presentation that I gave before, as well as the orange presentation, too. And hopefully this will open up a whole new world for many of you. So the title is Problems with the Current Theory of Insect Olfaction. And the reason why I am talking about this is because I have been talking about insect olfaction for a long time. Oftentimes when I go to conferences, and it is in this that someone invariably raises their hand, it's very, very common, and asks why I'm introducing a new current theory of insect olfaction. What's wrong with the old one? So this is one of those times where I'm going to need to discuss some of the problems with the current theory of insect olfaction so that you can be open to what I have to say in presentations two, three, and four. And so that's what I will attempt to do today. It was in 2016 that we deciphered the insect olfactory code. It was a long time in waiting. I've been kind of wondering about this, especially since the 90s. More seriously, since the beginning 2000, about 2003. And then in 2016, we were able to decipher it. And I'm going to give you a little window into that, especially for presentations three and Four. But right now I have to deal with this. I've got to get through this. You have to understand, everyone should understand if you want to move on, that there are problems with the current theory of insect olfaction. And I'm now going to talk about them in sufficient detail. Not a huge amount of detail, but sufficient detail. So let us begin. So they are right there. AEA has hired me as their scientific advisor. I'm very thankful for that. Thankful that they give me opportunities to get out of the laboratory, to even speak on webinars such as this. And let's go ahead and begin the show. Olfaction and insects. How is it accomplished? It is thought to be well known. I mean, if you talk to most of the entomologists, especially if they're involved in insect olfaction, they will tell you that we've got a pretty good idea of how insect olfaction occurs. It's just the details that we're working out. And so the big question is how exactly is it accomplished? And I am going to spend some time during this presentation. I am going to be required in order to give you a brief overview of insect olfaction. And I'm going to give you the brief overview as to how it is taught in the universities, how it is taught in the textbooks, to give you that background information that you will need. And then after I give you that brief interview, I am going to proceed to rip it apart. Let's begin with insects. How do they smell? How does insect olfaction occur? We're all in agreement that it's all about the antenna. There are some other taste receptors and olfactory receptors in different parts of the body. The legs, the tip of the legs, the wings, the back of the insect has some taste receptors near the ovipositor. But generally speaking, this is all about the antenna. The antennae are picking up these odorants and detecting them. Exactly how this is occurring is going to be briefly discussed. So I've just got this large Saturn IAD or giant silk moth here, the Atlas moth, to show you how plumose and how our bipectinate antenna, and how beautiful too, how some of these antennae can actually be. But if we get a close up, it sometimes loses some of its beauty because off to the right there you see a close up of an actual antenna on an insect and you have a lot of hairs coming out of them. Those are the individual segments that are listed here. You can see the demarcations in between them. But it's the hairs that I think everyone Kind of focuses on. And these hairs are what I will be focusing on as well. So the most common hair or sensilla or odorant detecting mechanism on an insect are called the Sensillae trichodia. And they are these long hairs which are sticking out, and trich is hair. Therefore, they are simply named after hair because they are hair. Like they're not actual hairs, but that's what they look like. We have another type of sensilla with the Sensilia coelaconica here on the insect as well. These are significantly smaller. There's only a handful of them on this particular insect, but we have the central receiver surrounded by a number of modifiers on the outside, and that's a different type. And I just wanted to say ever so briefly that there are 400 different types of sensillae on arthropods. So if you include the insects, spiders, scorpions, mites, all of the senseli that are out there, about 400 different types, and all of them are designed to either taste or smell odorants. But the actual shape has not been discussed, despite the fact that we have 400 different shapes associated with them. So I want to focus on a cross section of one of these hairs next. So let's take a look at one of these hairs, the Sensila trichodia. This cross section is showing you that it is hollow. So on the inside of it, there.

Is.

Essentially a watery matrix, a sensilla lymph. And on the inside, there are, in this particular case, we have two neurons that extend up. They kind of look like spaghetti strands. And they are considered to be the detectors of the odorants. The odorants are said to be out in the air. So here we have a basic lepidopteran pheromone, a fatty acid. And they are purported to make their way through these tiny pores in the side of the scilla. You cannot see them on the left because they are microscopic, running about 10 to 15 nanometers. And these pheromones make their way through these tiny pores and then make their way in to the sensilla lymph in order to be detected by these dendrites. And then the message is sent to the brain. So that's what a cross section of a Sensilla trichodia looks like. And all the others have a similar type of cross section with a few different variations which are not important to my discussion. So originally, this is now a diagrammatic of what we just showed you. Right there. I've got the air on the outside I've got some pheromone molecules which are designated by blue balls, blue circles. And it was originally thought that these pores had conduits that led directly to the receptors on those spaghetti strands. The spaghetti strands are represented by the neuronal cytoplasm, the receptor, and many SNMPs, another type of possible receptor on insects too. It was originally thought that this is how it worked, and it kind of needed to, because the pheromones needed to diffuse from the air to the receptor itself. And that is what they were purported to do. This was back in the 60s, and since diffusion occurs 10,000 times faster in air, it made sense that you would have these conduits because we knew insects could smell pretty fast. And so having these conduits there there was very helpful. It was supposed that the pheromones simply diffused through the pores, made their way through this conduit to the receptor, and that's how they smelled. We have since learned that that is not the case, that these conduits do not extend all the way to the receptor. And because of that, we're now left with a watery matrix or sensillar lymph that the pheromone needs to get through in order to get to these receptors. But that's only one of the problems. Another problem is that we discovered that there are pheromone degrading enzymes on the outside of the sensila. Steve Furkovich back in the 70s was able to show that there are some enzymes which are breaking down the pheromones on the outside of the sensilla. Well, this is also a problem because why is it breaking it down? How are they going to detect pheromones if they're being broken down as soon as they land on the sensilla? Well, the situation got worse because we found pheromone degrading enzymes on the inside as well. So should any pheromone molecules get through the pores and on the inside, and they didn't get picked off on the outside, they were going to get picked off on the inside because the pheromone degrading enzymes, sometimes just known as PDEs, were in there taking apart the pheromones first chance that they got. So this was a problem seeming that the insect seemed to be setting itself up to prevent itself from smelling anything, and things got a little bit worse. And when we realized that many of the lapidoptera and pheromones, the butterflies and the moths, have long chain fatty acids, long chain fatty acids. As the name suggests, they're fatty acids. And fats don't mix. Water and oil don't mix. Oil is a fat. And because they don't mix, there was really no way for these pheromone molecules to diffuse in this watery matrix. In addition to being picked off by the PDEs, there was no way for them to dissolve. On the inside, a discovery was found. The pheromone binding proteins. The pheromone binding proteins, designated here by a red pentagon, had the job of attracting and binding an actual pheromone. Once it did so, it protected it. So it protected it so that it wouldn't get picked off by a pde, a pheromone degrading enzyme, and it was able to ferry boat this pheromone across the sensilla lymph without being attacked. So this was a good mechanism to come up with because they needed to overcome the problem of.