Simpson / Casas Advances in Insect Physiology

Physiology of Human and Animal Disease Vectors
1. Auflage 2009
ISBN: 978-0-08-088873-6
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, Band Volume 37, 350 Seiten

Reihe: Advances in Insect Physiology

This latest volume in this series contains articles on the physiology of human and animal disease vectors. The papers in this special issue give rise to key themes for the future and make progress towards answering such questions as:How do insect vectors of disease find their animal hosts?Once a host is located, how do insects deploy their intricate mouthparts and the extraordinary complexities of salivary chemistry to secure a blood meal? - Contributions from the leading researchers in entomology - Discusses the physiological diversity in insects - Includes in-depth reviews with valuable information for a variety of entomology disciplines

Autoren/Hrsg.

Simpson, Stephen

Casas, Jerome

Inhaltsverzeichnis

1;Front Cover
;1
2;Advances in Insect Physiology
;4
3;Copyright Page
;5
4;Contents
;6
5;Contributors
;8
6;Preface
;10
7;Chapter 1: Orientation Towards Hosts in Haematophagous Insects: An Integrative Perspective
;12
7.1;1 Introduction

;13
7.2;2 Functional neuroanatomy ;14
7.3;3 A brief history of haematophagy ;16
7.3.1;3.1 The Relationship Between Insects And Vertebrate Hosts
;17
7.3.2;3.2 Feeding on Blood
;17
7.4;4 The host signals

;18
7.4.1;4.1 Odours
;18
7.4.2;4.2 Heat
;19
7.4.3;4.3 Water Vapour
;21
7.4.4;4.4 Visual Cues
;23
7.5;5 Looking for food

;25
7.5.1;5.1 Activation
;26
7.5.2;5.2 Appetitive Search
;26
7.5.3;5.3 Host Detextion
;27
7.5.4;5.4 Host Finding
;27
7.5.5;5.5 Host Contact
;28
7.5.6;5.6 Host Biting
;28
7.5.7;5.7 Food Recognition and Feeding
;29
7.5.8;5.8 Leaving the Host
;31
7.6;6 Stimulus propagation and sensory reception

;31
7.7;7 Orientation mechanisms

;34
7.8;8 Thermal sensing in kissing bugs

;37
7.9;9 Sensory parsimony

;45
7.9.1;9.1 Parsimonious Use of Information In Blood-Sucking Insects
;45
7.9.2;9.2 Practical Consequences
;46
7.10;10 State-dependency of host-seeking behaviour

;47
7.10.1;10.1 The Temporal Modulation of the Response to Odours
;48
7.10.2;10.2 Maturation and Responsiveness
;49
7.10.3;10.3 The Modulation of Host-Seeking Activity by Reproduction
;50
7.10.4;10.4 Feeding Conditions and Host Searching
;51
7.11;11 Why some people are bitten more than others?
;52
7.12;12 Learning and memory
;53
7.13;13 Repellents, how they work

;53
7.14;14 Conclusions and perspectives

;54
7.15;Acknowledgments;59
7.16;References;59
8;Chapter 2: From Sialomes to the Sialoverse: An Insight into Salivary Potion of Blood-Feeding Insects
;70
8.1;1 Insects discover blood as food;71
8.2;2 Blood feeders like fast food: A historical perspective;74
8.3;3 Problems faced by arthropods when taking blood;75
8.3.1;3.1 Haemostasis
;75
8.3.2;3.2 Inflammation
;77
8.3.3;3.3 Annoying Itching
;78
8.3.4;3.4 hellip and pain hellip
;81
8.3.5;3.5 The Attacked Endothelium Fights Back
;81
8.3.6;3.6 Microbiological Concerns
;81
8.4;4 Toward a longitudinal definition of the salivary components of blood-feeding insects
;81
8.4.1;4.1 Enzymes
;82
8.4.2;4.2 Receptor Antagonism and Platelet Aggregation Inhibitors

;86
8.4.3;4.3 Physiological Antagonists, Primarily Vasodilators
;87
8.4.4;4.4 Kratagonists
;88
8.4.5;4.5 Protease Inhibitors
;91
8.4.6;4.6 Anaesthetics
;93
8.4.7;4.7 Antigen (Ag5) Family Members
;98
8.4.8;4.8 Immunity-Related Products
;98
8.4.9;4.9 The Unexpected
;99
8.5;5 Salivary diversity;99
8.6;6 The evolutionary scramble;101
8.7;7 On the odd, the paradoxical, the bizarre and the bias;105
8.8;8 Measuring the size of our ignorance;106
8.8.1;8.1 A Forecast of the Costs and Time Required for Acquiring Sialome Wisdom
;110
8.9;9 Salivary antigens: Epidemiological tools?;110
8.10;Acknowledgments;111
8.11;References
;111
9;Chapter 3: The Enemy Within: Interactions Between Tsetse, Trypanosomes and Symbionts
;130
9.1;1 Background;131
9.1.1;1.1 Human and Animal Trypanosomiases
;131
9.1.2;1.2 Trypanosome Species
;132
9.1.3;1.3 Tsetse Identification and Distribution
;133
9.1.4;1.4 Tsetse Life Cycle and Physiology
;134
9.1.5;1.5 Trypanosome (t. brucei sspp.) life cycle: development and differentiation
;137
9.2;2 Tsetse-trypanosome interactions;140
9.2.1;2.1 Parasite Surface Coat
;141
9.2.2;2.2 Host Blood Factors
;142
9.2.3;2.3 Tsetse Midgut Environment and Signals for Differentiation
;144
9.2.4;2.4 Trypanosomes and Tsetse Digestive Enzymes
;145
9.2.5;2.5 Tsetse Immune System
;146
9.2.6;2.6 Effects of Trypanosome Infection on Tsetse Physiology
;159
9.2.7;2.7 Fly Sex, Age and Starvation and Trypanosome Transmission
;160
9.2.8;2.8 Environmental Temperature and Trypanosome Transmission
;162
9.3;3 Symbiont-tsetse-trypanosome interactions;163
9.3.1;3.1 Wigglesworthia Glossinidius
;163
9.3.2;3.2 Wolbachia Pipientis
;164
9.3.3;3.3 Sodalis Glossinidius
;164
9.4;4 Towards new methods of disease control;167
9.4.1;4.1 Gene Knockdown in Glossina

;167
9.4.2;4.2 Paratransgenesis
;169
9.5;5 Conclusion;170
9.6;Acknowledgments;171
9.7;References;171
10;Chapter 4: Interactions of Trypanosomatids and Triatomines
;188
10.1;1 Introduction;188
10.2;2 Triatomines;189
10.2.1;2.1 Distribution
;189
10.2.2;2.2 Development
;190
10.2.3;2.3 Intestinal Tract, Digestion and Excretion
;193
10.2.4;2.4 The Intestinal Microenvironment
;194
10.3;3 The trypanosomatids;201
10.3.1;3.1 Distribution of Species and Strains
;201
10.3.2;3.2 Developmental Cycle in the Triatomines
;206
10.4;4 Effects of the host on trypanosomatids;209
10.4.1;4.1 Susceptibility and Refractoriness
;209
10.4.2;4.2 Effects of Ph, Osmolality and Ionic Composition
;211
10.4.3;4.3 Effects of the Border Face
;211
10.4.4;4.4 Effects of Microorganisms and Antimicrobial Compounds
;214
10.4.5;4.5 Effects of Digestion, Digestion Products and Excretion
;215
10.4.6;4.6 Effects of Other Soluble Factors
;220
10.5;5 Effects of trypanosomatids on triatomines;221
10.5.1;5.1 Classification of Pathogenicity and Action of Secondary Stressors
;221
10.5.2;5.2 Pathogenicity of Blastocrithidia Triatomae and Trypanosoma Rangeli
;222
10.5.3;5.3 Subpathogenicity of Trypanosomatids in Triatomines
;228
10.6;6 Interactions in double infections;230
10.7;7 Conclusions;231
10.8;Acknowledgments;231
10.9;References;231
11;Chapter 5: Lyme Disease Spirochete–Tick–Host Interactions
;254
11.1;1 Introduction;254
11.2;2 Tick biology and physiology;255
11.2.1;2.1 Argasidae
;256
11.2.2;2.2 Ixodidae
;257
11.2.3;2.3 Feeding Characteristics of Ixodid Ticks
;258
11.2.4;2.4 Host Responses to Tick Feeding
;259
11.2.5;2.5 Anti-Haemostatic Tick Salivary Components
;260
11.2.6;2.6 Anti-Inflammatory Tick Salivary Components
;266
11.2.7;2.7 Immunosuppressive Tick Salivary Components
;270
11.2.8;2.8 Tick Midgut Components
;278
11.2.9;2.9 Tick Haemolymph Components
;281
11.3;3 B. burgdorferi biology and interaction with tick vectors;283
11.3.1;3.1 Genome of b. Burgdorferi
;283
11.3.2;3.2 b. Burgdorferi genes that facilitate tick colonization and persistence
;284
11.3.3;3.3 Tick Proteins that Facilitate Borrelia Transmission
;288
11.4;4 Summary;290
11.5;Acknowledgments;290
11.6;References;290
12;Chapter 6: Epidemiological Consequences of the Ecological Physiology of Ticks
;308
12.1;1 Introduction;308
12.2;2 Physiological adaptations for tick feeding habits;310
12.2.1;2.1 Cuticle Structure and Function
;311
12.2.2;2.2 Adaptive Patterns of Cuticular Wax Deposition
;312
12.2.3;2.3 Respiration and Metabolic Rates;315
12.3;3 Water balance, defence and consequences for pathogen conveyance;316
12.3.1;3.1 Osmoregulation: Spitting into The Host
;316
12.3.2;3.2 Immunomodulation: Salivary Pharmacology;317
12.3.3;3.3 Pathogen Traffic;320
12.4;4 Seeking a host - Where and when?;321
12.4.1;4.1 Water Balance Constraints;322
12.4.2;4.2 Sensory Systems;325
12.4.3;4.3 Recruitment of Unfed Ticks to The Questing Population;327
12.4.4;4.4 Fat Reserves Determine Lifespan;334
12.5;5 Epidemiological consequences of tick phenology;334
12.5.1;5.1 Focal Distribution of Tick-Borne Encephalitis;335
12.5.2;5.2 Widespread, but Partitioned, Sistribution of B. Burgdorferi S. L.;337
12.5.3;5.3 Sensitivity to Climate Versus Impact of Climate Change;338
12.6;6 Conclusions;339
12.7;Acknowledgments;340
12.8;References;340
13;Index
;352
14;Color Plates
;360

Leseproben

Chapter 1 Orientation Towards Hosts in Haematophagous Insects

An Integrative Perspective

Claudio R. Lazzari

Institut de Recherche sur la Biologie de l'Insecte, UMR 6035 CNRS – Université François Rabelais, Faculté des Sciences et Techniques, Av. Monge, Parc Grandmont, 37200 Tours, France

Abstract

A common problem for organisms is the localization, in space and time, of the resources necessary for survival using information from the environment. Haematophagous insects depend on vertebrate blood for their survival and reproduction. Their food sources are thus unique in that it is not in the host's interests to be bitten (it can defend itself), the host is mobile, and the food circulates inside vessels beneath the host's skin. An insect's response to any stimulus depends on its sensory capacity and the way the gathered information is processed by their central nervous system. Here, I discuss how haematophagous bugs acquire and use information associated with their hosts, to efficiently feed on hosts' blood. I will describe the role of physical and chemical cues in each step of the feeding process, in particular the role of thermal sensing how multimodal cues are integrated to facilitate the exploitation of a potential host. The parsimonious use of the same type of information to exploit different resources in different contexts is also discussed, as are the mechanisms underlying modulation of haematophagous behaviour by an insect's physiological state.

1. Introduction

Neuroethology (‘neuro’ Greek; related to nerve cells, ‘ethos’ Greek; habit or custom) addresses the neural basis of animal behaviour, through an evolutionary and comparative approach. Its main focus is understanding how the central nervous system translates biologically relevant stimuli into behavioural activity (Ewert, 1980).

Various notions about the origins and goals of neuroethology exist (Ewert, 1980, Hoyle, 1984, Bullock, 1990 and Pfluger and Menzel, 1999). However, the main questions addressed in this area of study, by means of experimental exploration, are as follows (Ewert, 1980):

• (1)
  Which sensory processes are responsible for distinguishing between behaviourally relevant and irrelevant stimuli?
• (2)
  How are signals localized in space and time?
• (3)
  How is information acquired, stored and recalled?
• (4)
  What is the neurophysiological basis for the motivation of a behavioural pattern?
• (5)
  How is behaviour coordinated and controlled by the central nervous system?
• (6)
  How is behaviour ontogeny related to neuronal mechanisms?

Insect neuroethology is a well-developed field, thanks to advances in the development of several model systems. Studies on some of the major topics, such as wind-triggered escape, the recognition of acoustic signals, learning and memory and others, have provided considerable insight into how the nervous system controls adaptive behavioural responses in insects. The particular species chosen for detailed analysis in such studies include honeybees, cockroaches, crickets, flies and a few others. However, no blood-sucking insects are included in this “select” group, even though some of them are classical models in insect physiology (e.g. Rhodnius prolixus) or the subject of intense study due to their impact on human health (mosquitoes). This does not mean that we lack information on their behaviour and neurobiology. On the contrary, important aspects of their behaviour, sensory physiology and functional neuroanatomy have been extensively studied. Nevertheless, very few studies have analysed this aspects with an integrative view in haematophagous insects. In this chapter, I summarize the current understanding of the physiological mechanisms that underlie host-seeking in blood-sucking behaviour, with an integrative view, to elucidate some of the issues described above.

2. Functional neuroanatomy

To understand the neurobiological basis of behaviour, we firstly need to understand the organization of the nervous system. Functional neuroanatomy provides the basis for focusing physiological studies on the neural elements associated to a particular behaviour. A series of detailed studies have been published over the past few years on the functional neuroanatomy of mosquitoes, particularly Aedes aegypti and Anopheles gambiae. These studies have revealed the neural architecture of the olfactory brain and the organization of sensory pathways from the antennae, maxillary palps and labium (Anton, 1996, Anton et al., 2003, Anton and Rospars, 2004, Ignell and Hansson, 2005, Ignell et al., 2005, Ghaninia et al., 2007a, Ghaninia et al., 2007b and Siju et al., 2008).

Some of the most significant findings of these studies concerning these malaria and yellow fever mosquitoes ( A. gambiae and A. aegypti, respectively) are described below:

• ?
  In A. gambiae, antibody labelling and subsequent three-dimensional reconstructions of the antennal lobes showed that males have 61 glomerular neuropils and females have 60. The size of the antennal lobe and of individual glomeruli was also tested for sexual dimorphism (Ghaninia et al., 2007b).
• ?
  In A. aegypti, sexual dimorphism has been demonstrated both for the number of total glomeruli (49 in males and 50 in females) and size of certain glomeruli (Ignell et al., 2005).
• ?
  Maxillary palp projections in A. aegypti are restricted to two posteromedial glomeruli, which do not receive antennal afferents. These include nerve projections from carbon dioxide receptors, which project to a single glomerulus (Anton, 1996 and Anton et al., 2003).
• ?
  Five non-overlapping projection zones were identified within the antennal lobe of A. gambiae, with one zone receiving input exclusively from maxillary palp sensilla and two zones each receiving input exclusively from trichoid or grooved-peg antennal sensilla (Anton and Rospars, 2004).
• ?
  Extensive serotonergic neurohemal plexi have been observed in the peripheral chemosensory organs of A. aegypti and A. gambiae, that is in the antenna, the maxillary palp and the labium, suggesting a potential role of serotonin as a neuromodulator in the chemosensory system (Siju et al., 2008).
• ?
  The central projections of the contact chemoreceptors in the labium and cibarium of A. gambiae and A. aegypti have been described in detail (Ignell and Hansson, 2005).

Notably, despite the differences in feeding habits between male and female mosquitoes, sexual dimorphism in the olfactory brain is not very marked, at least in terms of anatomical differences. Given the specificity and sensitivity of sensory organs dedicated to perceiving specific host-associated cues in females but not in males, one would expect a greater divergence between the sexes, but this does not seem to be the case. This could be related to the fact that both sexes feed on nectar, with females additionally sucking on blood. Even assuming that both males and females detect the same plant-associated volatiles and that certain chemical cues are common to both plants and animals (Syed and Leal, 2007), one would still expect a greater difference between the olfactory brains of males and females. It is possible that the glomeruli responsible for processing host-specific signals in females are, in males, involved in processing signals specific to this sex. This would thus allow for physiological dimorphism that it is not anatomically visible.

Neuroanatomical studies of Hemiptera have focused on bedbugs and kissing bugs. Whereas studies on bedbugs have been mostly limited to the general anatomy of the central nervous system (Singh et al., 1996), more complete sets of data are available on the neuroanatomy of kissing bugs. Indeed, following on from the classical studies of V.B. Wigglesworth on the histology of the peripheral and central nervous systems in R. prolixus (Wigglesworth, 1953, Wigglesworth, 1959a and Wigglesworth, 1959b), further studies described the general anatomy of their central nervous system, the organization of antennal lobes and the ocellar and mechanosensory pathways (Barth, 1952, Barth, 1976, Insausti, 1994, Insausti and Lazzari, 1996, Insausti and Lazzari, 2000a and Barrozo et al., 2009).

Recent studies on triatomines suggest that there is no sexual dimorphism in the organization of the antennal lobes (Barrozo et al., 2009). This is not surprising, given that, in contrast to mosquitoes, both sexes feed on vertebrate blood, and no marked difference has been found in the number and type of sensory organs between males and females. Another interesting finding, meriting further analysis, is the fact that antennal inputs do not only project into the deutocerebrum, but descend further along the ventral nervous chain, synapsing nervous elements in the suboesophageal, porthoracic and posterior (meso+methathoracic+abdominals) ganglia (Barrozo et al., 2009). These kind of direct connections had been previously...