Ecology of Invertebrate Diseases

A rapidly growing interdisciplinary field, disease ecology merges key ideas from ecology, medicine, genetics, immunology, and epidemiology to study how hosts and pathogens interact in populations, communities, and entire ecosystems. Bringing together contributions from leading international experts on the ecology of diseases among invertebrate species, this book provides a comprehensive assessment of the current state of the field. Beginning with an introductory overview of general principles and methodologies, the book continues with in-depth discussions of a range of critical issues concerning invertebrate disease epidemiology, molecular biology, vectors, and pathogens. Topics covered in detail include:

• Methods for studying the ecology of invertebrate diseases and pathogens

• Invertebrate pathogen ecology and the ecology of pathogen groups

• Applied ecology of invertebrate pathogens

• Leveraging the ecology of invertebrate pathogens in microbial control

• Prevention and management of infectious diseases of aquatic invertebrates

Ecology of Invertebrate Diseases is a necessary and long overdue addition to the world literature on this vitally important subject. This volume belongs on the reference shelves of all those involved in the environmental sciences, genetics, microbiology, marine biology, immunology, epidemiology, fisheries and wildlife science, and related disciplines.

Autorentext

ANN E. HAJEK, PHD, is a Professor in the Department of Entomology, Cornell University, Ithaca, New York, US. DAVID I. SHAPIRO-ILAN, PHD, is a Research Entomologist at USDA-ARS, Byron, Georgia, US.

Inhalt
List of Contributors xvii

Preface xxi

Section I Introduction 1

**1 General Concepts in the Ecology of Invertebrate Diseases 3
**Ann E. Hajek and David I. Shapiro-Ilan

1.1 Introduction 3

1.1.1 What Is Disease? 4

1.1.2 Terminology and Measurements 5

1.1.2.1 Prevalence/Incidence 5

1.1.2.2 Pathogenicity/Virulence 5

1.1.2.3 Infection/Infectivity 6

1.1.2.4 Immunity 6

1.1.2.5 Transmission 7

1.1.2.6 Epizootic and Enzootic Diseases 7

1.1.2.7 Cycles of Infection 8

1.1.2.8 R0 and the Host Density Threshold 10

1.1.3 Factors Influencing the Ecology of Invertebrate Diseases 11

1.1.3.1 Host Range 12

1.2 Types of Studies 13

1.3 Why Study the Ecology of Invertebrate Diseases? 13

1.4 What this Book Covers 14

Acknowledgments 16

References 16

**2 Methods for Studying the Ecology of Invertebrate Diseases and Pathogens 19
**Raquel Campos-Herrera and Lawrence A. Lacey

2.1 Introduction 19

2.2 Traditional Methods for Studying Diseases 19

2.2.1 Sampling Goals 19

2.2.2 Sampling Regimes 20

2.2.3 Methodologies 20

2.2.3.1 Searching for Infected Insects Using General Entomological Sampling Methods 23

2.2.3.2 Selective Media 23

2.2.3.3 Extraction Methods 24

2.2.3.4 Airborne Spore Sampling 24

2.2.3.5 Insect Baiting 24

2.2.3.6 Dispersal of Entomopathogens: MarkReleaseRecapture Method 25

2.3 Molecular Tools to Assist in the Detection and Quantification of Pathogens and their Impact on the Host 25

2.3.1 Employment of Proteins: The Beginning of the Molecular Era in Invertebrate Pathology 26

2.3.2 Techniques Based on the Nucleic Acids: the Pre?]Omics Era 27

2.3.3 Advanced Techniques: qPCR, NGS, and the Arrival of the ?]Omics Era 31

2.4 Traditional Versus Molecular Methods: Advantages and Limitations 33

2.5 Advancing the Frontiers of Ecology using Pathogens and Diseases 36

2.6 Conclusion38

Acknowledgments 38

References 38

Section II The Basics of Invertebrate Pathogen Ecology 49

**3 The Pathogen Population 51
**Leellen F. Solter and James J. Becnel

3.1 Introduction 51

3.2 Characteristics of Pathogens 51

3.2.1 Invasiveness and Infectivity 52

3.2.1.1 Routes of Entry 53

3.2.1.2 Establishment of Infection and Tissue Tropism 54

3.2.2 Pathogenicity, Virulence, and Pathogen Replication 55

3.2.2.1 Virulence Factors 57

3.2.2.2 Attenuation or Enhancement of Virulence 58

3.2.3 Latency 59

3.2.4 Obligate, Opportunistic, and Facultative Pathogens 60

3.2.5 Transmission 61

3.2.5.1 Horizontal Transmission 61

3.2.5.2 Vertical Transmission 62

3.2.5.3 Indirect Transmission 63

3.2.6 Genetic Variability and Potential for Coevolution with Hosts 64

3.2.6.1 Species and Strains 64

3.2.6.2 Host Specificity 65

3.3 Pathogen Effects on Host Development and Behavior 66

3.4 Pathogen Populations 67

3.4.1 Density?]Dependent Pathogens 67

3.4.2 Density?]Independent Pathogens 68

3.4.3 Pathogen Persistence in the Host Population 68

3.4.3.1 Chronic Infections and Vertical Transmission 69

3.4.3.2 Alternative and Alternate/Intermediate Hosts 69

3.4.3.3 Pathogen Survival in Cadavers and in Plant Tissues 70

3.4.3.4 Latency in Host Populations 70

3.4.4 Persistence of Pathogen Stages in the Environment 71

3.5 Dispersal and Spatial Distribution of Pathogens 72

3.5.1 Physical Factors: Wind and Water Dispersal 73

3.5.2 Biological Factors 73

3.5.3 Spatial Distribution 74

3.6 Pathogen Interactions 75

3.6.1 Interactions with other Biological Agents 75 3.6.2...