[BELLS RINGING] SPEAKER 1: This is a production of Cornell University.
SPEAKER 2: Insects are the most successful multicellular organism on our planet, and new discoveries about them help us understand the natural world. Reginald Chapman's The Insects has been the standard textbook in the field since the first edition was published more than 40 years ago.
Building on the strengths of the original text, the richly illustrated fifth edition brings his classic work up to date for the molecular era. In a Chat in the Stacks book talk at Cornell University's Mann Library, editor Angela E Douglas touches on Dr. Chapman's original work and the process of producing the fifth edition with an international team of eminent insect physiologists.
Dr. Angela Douglas is the Daljit S and Elaine Sarkaria Professor of Insect Physiology and Toxicology at Cornell University. She is a fellow of the Royal Entomological Society and the Entomological Society of America.
ANGELA DOUGLAS: Can everyone hear me OK? Yes. I'd very much like to take the opportunity to thank both Mary and Lynn for inviting me and for organizing this event. Thank you so very much, and thank you everyone for coming along.
The Chats in the Stacks are about authors, for authors of recently published books. And this requires me, really, to do a little bit of explaining because at one level, the people who are responsible for this book are indeed myself and Steve Simpson. And here we are in celebratory mode.
Steve, my colleague, is-- just make quite sure I've got this right. No, I'm not understanding this. Steve, my colleague, is based at the University of Sidney in Australia. And you can see us here in celebratory mode on the publication of this book when I visited him last month in Australia.
But actually, we aren't really the authors of this book at all. The author is one Reginald Frederick Chapman. And here's the evidence. Here he is preparing the book.
The other way in which I have to do a little bit of explaining is that, yes, indeed, this version, the fifth edition, was published this year, but actually, it's a book with a long history. And this is obvious. There's a clue to that from the picture of Reg on the far side. And you can see he's preparing illustrations.
And notice there's not a computer screen in sight. He's preparing illustrations with a fine black ink pen. And he's got scissors and glue, and he is putting together his illustrations, which is telling us that this book has a long history. In fact, the first edition was published in 1969.
So what I'd like to do is, first of all, tell you a little bit about Reg, the author, the true author of this book. And then I want to tell you about the process by which the fifth edition was written. And the basis of this was really that no one, no one today could do what Reg did. And it took 24 authors to equal his expertise.
And I call him here Reg the Colossus, because he truly did bestride this narrow world of insect structure and function like a colossus. And I say that with real care because Reg was a true Brit. He didn't blow his own trumpet. And I'm sure that he would feel rather uncomfortable at being called a colossus. But it is evident to those of us who contributed to the fifth edition that that truly is what he was for this area.
And finally, I'm going to say a few words about what the fifth edition is seeking to achieve, providing a modern understanding of how insects work.
So I'm going to start off by telling you a little bit about Reg. And to do that, we need to go to a different time and to a different place. Really, we need to go to London in the 1960s, a time when Carnaby Street was the height of fashion-- doesn't it look quaint-- when the only thing that protected us from nuclear annihilation was to walk from Hyde Park to Aldermaston and back with Bertrand Russell and the Reverend Collins, and a time when modern music was being turned on its head by four young men from Liverpool.
Now, Reg couldn't really indulge in any of these frivolities of one sort or another because he had recently been provided with a job as a lecturer, or in American terms, an assistant professorship at Birkbeck College in London. And he was tasked with the job of putting on a master's course in entomology.
Now, Birkbeck College is a very interesting place. It's one of the London colleges. And it was set up in the 1820s by the Reverend Birkbeck, Jeremy Bentham, and a number of other luminaries of the time to provide education for working people.
And remarkably for the time-- it opened in 1825. And the first people admitted were men, but within five years, women were admitted as well. And this was a tremendous achievement for 19th century Britain because for much of the 19th century most men would be able to tell you that women were too feeble-minded to be given a university education. But they were at Birkbeck College.
And because it was for working people, the doors opened at 6 o'clock in the evening, and lectures and classes were between 6:00 and 10:00 at night. And that is still the case today. It is a very, very special college.
And I have lectured there as a visiting lecturer, and I can assure you that it is a very different experience. The students are very diverse in all sorts of different ways, very inquisitive. And it's tough work.
And I've told you all this detail because I think it's important because what Reg did was write up his lecture notes from that really tough experience of teaching at Birkbeck College-- and I mean tough in the very best sense of the word-- as a book. And the first edition was an enormous success.
In fact, the second edition came out just three years later. A decade later was the third edition. And 1998 was the fourth edition.
And his textbook on the insects really reflects his lifelong commitment to education and students. In addition to the four editions of The Insects, he wrote-- edited a book on the regulatory mechanisms of insect feeding, which is very much a bible for those of us who are interested in such things, a book on the biology of grasshoppers, and with Liz Bernays, a very important book on host-plant selection by insects.
And all of this may sound a little bit stuffy, but one thing that Reg was not was stuffy. He was great fun and a great entertainer, and I'd like to illustrate this by a picture that Liz Bernays provided to me. In fact, all the pictures of Reg that I'm displaying were kindly provided by Liz.
And here is Reg at a party reminding everyone around him that the sensory world of an insect is kind of different from the sensory world of you or me. So put your feet on the ground. You can feel the ground beneath you. If you were an insect, you'd also be able to taste it. Insects have chemoreceptors on their tarsi, on their feet. And as Liz said to me, this picture is of Reg saying, just imagine if you could taste with your feet.
So more seriously, Reg made an enormous contribution. And the greatest part of his legacy is undoubtedly the insects, for this book very much framed the way that generations of insect scientists, the way that we think, the questions we ask, the way that we work. And this is, I think, for two reasons.
The first is he didn't indulge in the generalized insect. Every single-- almost every single-- example refers to a particular species or a particular family. And furthermore, he also had a beautiful way of writing. His words, they dance on the page. They sing to you. He was just a wonderful writer.
And really, this is the cruelty of scientific writing because it doesn't matter how wonderfully he did his illustrations with his black ink pen-- and many of those illustrations are in this fifth edition too-- nor how beautifully he wrote nor how accurate his science was because science moves on. And very soon the science that he wrote is incomplete.
Perhaps some of it is actually we now to be wrong. And it isn't what the next generation of entomologists and insect scientists need. And in this respect, writing science is really different from writing in other ways. We can pick up one of the classics-- I've got one of Charles Dickens's books here-- and read it with just as much entertainment and instruction as someone who picked up the first edition.
And I like to think that our grandchildren and great-grandchildren will be able to enjoy the wonderful books of this year's Nobel Prize winner of literature, Alice Munro, who is another person whose writing sings from the page. They will be able to enjoy it without any change or modification. But that is not the case for science because it dates.
So what were we to do? How could we enable another-- for future generations to appreciate and gain from what Reg Chapman was doing knowing that no one could be like Reg, that colossus, who has the knowledge and understanding of the diversity of insects and also an understanding of their physiology and how they work?
So Steve Simpson was very much the person, the motor behind this. And he and I came up with the conclusion, the only way to do it was like this-- 24 experts from four different continents. And we really can't thank our colleagues enough for taking on the task and entering into this with us. And all of our colleagues who contributed, I think they all really understood what we were trying to achieve, which was to continue what Reg had started but updating his chapters while maintaining that flavor.
Actually, by the time we got to this point, we thought that, well, our job was nearly over. But of course, we discovered very quickly that it had only just begun. And we spent four years doing this.
Our colleagues are wonderful colleagues, but they're also very good academics, and they like to do things their own way. But we were able to herd, and we were very lucky in that all our colleagues were indeed actually rather well behaved cats. And in the end, it was achieved. And we really do also thank Cambridge University Press for their patience and tolerance as we herded our cats together.
Anyway, we have now the fifth edition of The Insects. And what I'd like to do now is just tell you a little bit about how this book and all those people who contributed to the updating of Reg's achievement contributes to our modern understanding of how insects work.
And the first thing we have to really understand is that insects are fundamentally different in the way that they're organized and structured from people, mammals, and vertebrates. And this is really because if we look at the diversity of animals, the groups where we are, in the group called the chordates, and where the insects are, in the group called the arthropods-- and I'm just going to replace that crab by an arthropod-- I'm not worried about placing that lizard by a person, but we have to get our insects right-- that they are very different groups.
And the common ancestor of those groups was in many ways a very simple organism. So many of the complex organs that enable us to work evolved independently in the lineage giving rise to the insects versus the lineage giving rise to you and me. And I'd like to illustrate that. And I'm doing this in reverse order.
So lastly, by telling you a little bit about the tracheal system of an insect, which is how insects breathe-- and this is chapter 17. There are a total of 27 chapters in here. Chapter 17, updated by Jon Harrison from the State University of Arizona.
I'd also like to tell you a little bit about the insects' equivalent of kidneys, which are the malpighian tubules. And this chapter 18 was updated by Julian Dow from the University of Glasgow in the UK.
And I'm going to start off with a little bit of indulgence. I'm going to tell you about one of the chapters which Steve and I worked on together to update. And this was the chapter on nutrition. So let's start off with nutrition, and really you might anticipate that nutrition of insects is actually rather a boring subject.
And the reason why you'd expect it to be boring is that the nutritional characteristics of all animals were really set very early in their evolution. All animals as a group were metabolically very impoverished. And so we have a requirement for lots of different kinds of nutrients. That's what a balanced diet is all about.
It's not good that we need a balanced diet. It's actually very bad because it means we have to have certain kinds of nutrients, and it limits the sorts of places, habitats that we, as animals, can utilize. And in particular, we have a need for vitamins and essential amino acids. Look at the back of your cereal pack, which turns this limitation of being an animal into some sort of virtue.
But some insects, unlike us, really can defy animal nutritional science. And they can live on diets that no self-respecting animal can possibly do. For example, some can feed through the life cycle on vertebrate blood, grossly deficient in B vitamins. There is no way that any self-respecting animal could possibly do this, and yet some insects quite clearly, apparently, have for some 30 or more million years.
Similarly on plant sap, deficient in essential amino acids, and various insects that can feed on sound wood, which is a bit like you and me living our whole life on filter paper. We wouldn't get very far that way. And how they do it-- they do it because they have organs that have no parallel in us or indeed in any other mammal or vertebrate which contain micro-organisms that provide those nutrients.
So I sincerely hope that none of you have personal experience of lice, but if you have, I'm sure you'll appreciate that the only way that they can be this nasty parasite is because they have a special organ close to their gut called a stomach disc, which is packed full of bacteria that provide them with the B vitamins that are absent from their diet.
In the same way, the aphids and whiteflies and related species have an organ in their body cavity. In aphids, it's this u-shaped organ illustrated green here that is as large as the liver of you or me but differs from our liver in that it's packed full of bacteria that provide essential amino acids.
Similarly, bostrychid beetles-- and I sincerely hope you don't have them in your furniture, but you might do-- they have these large organs, indicated here, suspended by fine filaments from the gut. And those organs are full of bacteria that, again, are providing these nutrients.
And even the lowly cockroach, which I fear you might have come across, and if you hasn't, I'll invite you to Comstock Hall, where you will certainly encounter one, they, too, can only do what they do because their fat body has these special cells containing bacteria. So this is something that some insects can do that the lineage giving rise to us certainly can't.
I'd like now just to consider malpighian tubules. These are the renal organs of insects. You might say the insect kidneys. So I guess we're all familiar with our own kidneys, those paired kidney-shaped structures positioned just below the ribs. And they have no connection with our gut, physical connection to the gut at all.
Whereas in insects, the equivalent is the malpighian tubules, which are these sort of a bit like spaghetti-shaped structures. If you look at this figure from the mouth going to the anus taken directly from Reg's book, the malpighian tubules are these blind-ended outpocketings from the gut, just at the junction between the midgut and the hindgut. So the kidneys of an insect are actually linked directly to the gut.
Not only are they anatomically different-- sorry, I shouldn't have called them kidneys. I should have called them renal organs. Not only are the malpighian tubules of the insect different anatomically from those of you and me, but they're physiologically very different as well. So in our kidneys, each of our kidneys is made up of a million or more nephrons, in which the blood is passed through this fine capillary network, associated with, confusingly again, called malpighian body. But this is in the vertebrate.
And the high blood pressure forces water and various solutes through to form the primary urine, whereas in an insect it's not mediated by filtration but by secretion. The particular ions are secreted actively using energy across into the lumen of the malpighian tubule, a very different physiological mechanism for mediating the production of urine and excretion.
And all of this in relation to the malpighian tubules, one of the key workers who established this, was Arthur Ramsay in the 1950s. And this work is described in all of the editions of The Insects from first to fifth. And you might say that Arthur Ramsay entered into an alliance with the Indian walking stick. And he chose this insect because the malpighian tubules of this insect are remarkably easy to dissect and very robust.
And in fact, you can take them out, put them into saline or into insect blood or what have you, and they will continue to twitch and writhe like little snakes for hours and hours. And they will continue to mediate that secretion, excretion of-- as they do in the body.
So what he did was he had a glass slide, and here's the malpighian tubule of his walking stick. And in this diagram, it says it's in haemolymph, which is a fancy insect word for insect blood. And then he covered this with liquid paraffin so it wouldn't desicate. And then he took a hair from his own head and tied it to the end of the malpighian tubule, the open end, the end nearest the gut. And then he just pulled it out.
And the malpighian tubule continued to generate the urine, which was drop by drop exuded from the open end of the malpighian tubule. And this is energetically very expensive and requires lots of oxygen. So he made sure there was a little air bubble provided so that there was sufficient oxygen to keep this going. And he made use of this wonderful method to establish the mechanisms by which the urine is produced and excreted in the malpighian tubule.
You will find in the fifth edition, but none of the previous editions, additional information all about the genetic basis of the malpighian tubules. We have now the genomic revolution, and now we can start to understand how these malpighian tubules operate, not just at the level of movement of ions or so on, but also at the level of the function of the underlying genes.
I will not be testing you on the names of all these genes at the end of the class but tell you that one of the-- well, for us-- astonishing things that emerged from this work was that in spite of the fact that malpighian tubules and kidneys are anatomically and functionally so different, many of the same genes are actually underpinning that function.
And we can illustrate this just by one example, which is the gene for an enzyme called xanthine dehydrogenase. And there are some people, unfortunate people, who have a mutation in that gene, which means that they tend to accumulate a particular compound called xanthine. And when this reaches sufficiently high concentrations, it precipitates and causes kidney stones.
So here is a CT scan of a patient. You can see the backbone down the middle and the two kidneys. And these little white dots are those kidney stones. Now, there are many ways in which kidney stones can be formed, and this is just one of them, causing a disease called xanthuria.
It so happens that insects can suffer from exactly the same disease. And in fact, the very second mutation of the Drosophila fruit fly that was identified was a mutation, a null mutation, in precisely this gene. It's called rosy because it has the effect of converting the eye color from a wonderful rosy red of the wild type to brown.
But in addition and much more important than that, it causes a bloating of the malpighian tubules. So the xanthine comes down as little kidney stones in the malpighian tubule, and the malpighian tubules look very uncomfortable. We can't ask the insect if it's in pain, but I strongly suspect that all the rosy mutants that are to be found in Drosophila labs really are in great pain because they're suffering from essentially kidney disease.
So here we have a situation where we have excretion being mediated by two different organs with two different fundamental processes involving the same genes being recruited to serve the same ultimate function. So we have uniformity at the bottom at the top and variation at the physiological level.
And it is because of this that we can use Drosophila and indeed other insects as a biomedical model to understand the fundamental principles of this disease of xanthuria but also various other diseases as well. Even though Drosophila don't have kidneys and their physiology is different, we can still make use of them in a very effective way.
I'd like now to move on to the last of my three topics that I've taken out from this book. And this refers to the tracheal system. So we have to remember, of course, that the insects don't breathe through their mouth, and they don't have lungs. Well, cartoon insects do, but real insects don't.
Insects gain their oxygen through air holes or spiracles down the lateral side of their thorax and their abdomen. And they have air tubes ramifying through their tissues. So here's a figure from The Insects. And this is, if you imagine our locust here, and the head at one end, and then we the tail tip of the abdomen at this end.
It's a section through the abdomen taken through there so that you can see the central gut and the heart and the nerve cord. And at either side, there is a hole letting the air through via the spiracle. This is important, and I'll explain why in a moment. And this gives rise to these branching tracheal network of air-filled tubes that ramify through to make contact with the gut, with the heart, and with all the other organs.
I should mention at this point-- and I didn't mention before, and mentioning this in passing-- one of the other interesting features of insects can best be described if you'd like to put your hand to your heart, you do this. If you were able to ask an insect to do the same and ask it to put a leg to its heart, it would do this.
So the heart is a long tube down the dorsal side of the insect. If you can feel your backbone, that is actually where the heart of an insect is. So insects are just different.
But let me get-- that is by the way. I shouldn't be talking about hearts. I'm talking about tracheal systems. OK. So Jon Harrison has done some lovely work addressing the tracheal system. And I want to talk about this because many people think the only advances in insect science in the last decade or two relate to genomics. And this is a beautiful illustration of how making use-- or predominantly through genomics, and it's not like that at all.
There are wonderful advances using all sorts of other different approaches. And this is an illustration. It [AUDIO OUT] use sophisticated microscopical methods to map out the tracheal system in absolute detail, in this case, in a set of darkling beetles. And what he was particularly interested in arose from what seems at first sight as a design fault of insects, that as I mentioned a moment ago, there are spiracles on the abdomen and the thorax but no spiracles for the head and no spiracles for the legs.
And this means that the only way that they can get oxygen to the head and the legs is by a trachea, an air tube, going through the neck up to the head and through the junction, the orifice between the thorax and the leg. And so if we consider this figure just here, here is the area at the junction between the body and the leg. And within that, there is the trachea going through to provide the oxygen to the muscles of the leg.
So what Jon and his colleagues studied were these darkling beetles that varied 1,000 fold in their size, from the tiny little castaneum, a bit more than a milligram, down to Eleodes obscura, which is nearly 2 grams. And here is a diagram that illustrates what they found.
So the black points in the diagram are the four different beetles, the castaneum, the very small one at the far end going up to the obscura, the very largest one at the end nearest to me. And what they were able to show was that the cross-sectional area for the space between the thorax and the leg increased with increasing size of the insect more slowly than the increase in the size of the trachea that goes through.
We don't understand why that is. But I don't think it's difficult for us to imagine those two lines eventually converging, such that the trachea actually fills the whole space available. And unless something pretty extraordinary happens in terms of the organization of this system, this limits the size of the insect. You can't have an insect without legs, without oxygen.
And indeed they predicted on the basis of this that the largest insect would be about 14 to 15 centimeters in length. Actually, the largest insect of this form that we know is titanus giganteus, which is 17 centimeters. And this makes us suspect that this is absolutely right, that insect size, at least of this small form, is limited by the amount of space for those air tubes or trachea to get into the leg.
I'd just like to finish off by talking to you about a character in 20th century insect science that I suspect is the most famous of all, Gregor Samsa. Now, Gregor Samsa-- it all started for him one morning when he woke up from unsettled dreams, and he found himself transformed into a gigantic insect.
He lay on his hard armor-like back, and when he raised his head a little, he saw his vaulted brown belly divided into sections by stiff arches, from whose height the coverlet had already slipped. His many legs, which were pathetically thin compared to the rest of his body, flickered helplessly before his eyes. You don't actually need that picture at all, do you? And I hope you all recognize this, of course, as the opening paragraph of Franz Kafka's Metamorphosis.
Now, I'm mentioning this for two reasons, which I think try to encapsulate the two things I want to tell you. The first is that 40 years later, didn't require 24 international exports from four continents for us to enjoy or appreciate at least this wonderful story because this is not scientific literature. But you do need to read this book and books like this in order to appreciate that this can't possibly happen to you because the tracheal system wouldn't fit into the orifice between your body and your legs.
But let's just imagine for a moment that it could. I'm sorry to tell you, you wouldn't be able to leave your kidney stones behind. And if you were fit and healthy, your eyes would turn rosy red. Thank you very much, everyone.
SPEAKER 1: This has been a production of Cornell University on the web at Cornell.edu.
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Insects are the most successful multi-cellular organism on our planet, and new discoveries about them help us understand the natural world. Reginald Chapman's "The Insects" has been the standard textbook in the field since the first edition was published more than forty years ago. Building on the strengths of the original text, the richly illustrated 5th edition brings this classic work up-to-date for the molecular era.
In a Chats in the Stacks book talk Oct. 24, 2013 at Mann Library, editor Angela E. Douglas touches on Dr. Chapman's original work and the process of producing the 5th edition with an international team of eminent insect physiologists. Her talk provides examples of the volume's focus on form and function, bringing together basic anatomy and physiology, highlighting how these relate to behavior, and illustrating the importance of this comprehensive new edition as an essential reference tool for students, researchers, and entomologists.
Douglas is the Daljit S. and Elaine Sarkaria Professor of Insect Physiology and Toxicology at Cornell University. She is a Fellow of the Royal Entomological Society and the Entomological Society of America.