The Science of Forensic Entomology

David B Rivers, Loyola University Maryland, Maryland, USA Gregory Dahlem, Northern Kentucky University, Kentucky, USA

About the companion website xii

Preface xiii

Chapter 1 Role of forensic science in criminal investigations 1

Overview 1

The big picture 1

1.1 What is forensic science? 1

1.2 Application of science to criminal investigations 3

1.3 Recognized specialty disciplines in forensic science 9

Chapter review 10

Test your understanding 11

Notes 12

References cited 12

Supplemental reading 12

Additional resources 12

Chapter 2 History of forensic entomology 13

Overview 13

The big picture 13

2.1 Historical records of early human civilizations suggest understanding of insect biology and ecology 13

2.2 Early influences leading to forensic entomology 16

2.3 Foundation for discipline is laid through casework, research, war, and public policy 18

2.4 Turn of the twentieth century brings advances in understanding of necrophagous insects 21

2.5 Forensic entomology during the “great” wars 22

2.6 Growth of the discipline due to the pioneering efforts of modern forensic entomologists leads to acceptance by judicial systems and public 23

Chapter review 24

Test your understanding 26

Notes 26

References cited 26

Supplemental reading 27

Additional resources 27

Chapter 3 Role of insects and other arthropods in urban and stored product entomology 29

Overview 29

The big picture 29

3.1 Insects and other arthropods are used in civil, criminal, and administrative matters pertinent to the judicial system 29

3.2 Civil cases involve disputes over private issues 31

3.3 Criminal law involves more serious matters involving safety and welfare of people 31

3.4 Administrative law is concerned with rulemaking, adjudication, or enforcement of specific regulatory agendas 32

3.5 Stored product entomology addresses issues of both a civil and criminal nature 33

3.6 Urban entomology is focused on more than just “urban” issues 38

Chapter review 42

Test your understanding 44

Notes 45

References cited 45

Supplemental reading 46

Additional resources 46

Chapter 4 Introduction to entomology 47

Overview 47

The big picture 47

4.1 Insecta is the biggest class of the biggest phylum of living organisms, the Arthropoda 47

4.2 The typical adult insect has three body parts, six legs, two antennae, compound eyes, external mouthparts, and wings 50

4.3 Tagmosis has produced the three functional body segments of insects: the head, thorax, and abdomen 51

4.4 Sensory organs and their modifications allow insects to perceive and react to their environments 55

4.5 The structure and function of an insect’s digestive system is intimately tied to the food that it prefers to eat 57

4.6 A tubular tracheal system transports oxygen to the body’s cells while blood moves through the body without the aid of a vascular system 58

4.7 The nervous system of insects integrates sensory input and drives many aspects of behavior 60

4.8 In order to grow, insects need to shed their “skin” 61

4.9 Many insects look and behave entirely differently as a larva than as an adult – the magic of metamorphosis 61

4.10 The desire to reproduce is a driving force for unique reproductive behaviors and copulatory structures in insects 62

Chapter review 64

Test your understanding 65

References cited 66

Supplemental reading 67

Additional resources 67

Chapter 5 Biology, taxonomy, and natural history of forensically important insects 69

Overview 69

The big picture 69

5.1 A variety of different insects and terrestrial arthropods are attracted to a dead body 69

5.2 The fauna of insects feeding on a body is determined by location, time, and associated organisms 71

5.3 Necrophagous insects include the taxa feeding on the corpse itself 72

5.4 Parasitoids and predators are the second most significant group of carrion-frequenting taxa 85

5.5 Omnivorous species include taxa which feed on both the corpse and associated arthropods 87

5.6 Adventitious species include taxa that use the corpse as an extension of their own natural habitat 89

Chapter review 90

Test your understanding 92

References cited 92

Supplemental reading 94

Additional resources 94

Chapter 6 Reproductive strategies of necrophagous flies 95

Overview 95

The big picture 95

6.1 The need to feed: anautogeny and income breeders are common among necrophagous Diptera 95

6.2 Size matters in egg production 98

6.3 Progeny deposition is a matter of competition 100

6.4 Larvae are adapted for feeding and competing on carrion 102

6.5 Feeding aggregations maximize utilization of food source 103

6.6 Mother versus offspring: fitness conflicts 104

6.7 Resource partitioning is the path to reproductive success 105

Chapter review 106

Test your understanding 108

Notes 109

References cited 109

Supplemental reading 111

Additional resources 112

Chapter 7 Chemical attraction and communication 113

Overview 113

The big picture 113

7.1 Insects rely on chemicals in intraspecific and interspecific communication 113

7.2 Chemical communication requires efficient chemoreception 114

7.3 Semiochemicals modify the behavior of the receiver 115

7.4 Pheromones are used to communicate with members of the same species 116

7.5 Allelochemicals promote communication across taxa 118

7.6 Chemical attraction to carrion 120

7.7 Chemical attraction to carrion by subsequent fauna 122

Chapter review 124

Test your understanding 127

Notes 127

References cited 127

Supplemental reading 129

Additional resources 130

Chapter 8 Biology of the maggot mass 131

Overview 131

The big picture 131

8.1 Carrion communities are composed largely of fly larvae living in aggregations 131

8.2 Formation of maggot masses involves clustering during

oviposition or larviposition 132

8.3 Larval feeding aggregations provide adaptive benefits to individuals 134

8.4 Developing in maggot masses is not always beneficial to conspecifics or allospecifics 140

Chapter review 143

Test your understanding 145

References cited 146

Supplemental reading 149

Additional resources 149

Chapter 9 Temperature tolerances of necrophagous flies 151

Overview 151

The big picture 151

9.1 Necrophagous insects face seasonal, aseasonal, and self-induced (heterothermy) temperature extremes 152

9.2 Temperature challenges do not equal death: necrophagous insects are equipped with adaptations to survive a changing environment 153

9.3 Life-history features that promote survival during proteotaxic stress 154

9.4 Deleterious effects of high temperatures on necrophagous flies 158

9.5 Life-history strategies and adaptations that promote survival at low temperatures 160

9.6 Deleterious effects of low-temperature exposure 166

Chapter review 167

Test your understanding 170

Notes 171

References cited 171

Supplemental reading 174

Additional resources 174

Chapter 10 Postmortem decomposition of human remains and vertebrate carrion 175

Overview 175

The big picture 175

10.1 Decomposition of human and other vertebrate remains is a complex process 175

10.2 Numerous factors affect the rate of body decomposition 177

10.3 When the heart stops: changes occur almost immediately but are not outwardly detectable 179

10.4 Body decomposition is characterized by stages of physical decay 184

Chapter review 187

Test your understanding 190

Notes 190

References cited 190

Supplemental reading 192

Additional resources 192

Chapter 11 Insect succession on carrion under natural and artificial conditions 193

Overview 193

The big picture 193

11.1 What’s normal about terrestrial decomposition? Typical patterns of insect succession on bodies above ground 194

11.2 Succession patterns under forensic conditions are not typical 196

11.3 Several factors serve as barriers to oviposition by necrophagous insects 198

11.4 The physical conditions of carrion decay can function as a hurdle to insect development 200

11.5 Insect faunal colonization of animal remains is influenced by conditions of physical decomposition 204

Chapter review 208

Test your understanding 211

Notes 211

References cited 212

Supplemental reading 214

Additional resources 214

Chapter 12 Postmortem interval 215

Overview 215

The big picture 215

12.1 The time since death is referred to as the postmortem interval 215

12.2 The role of insects in estimating the PMI 217

12.3 Modeling growth–temperature relationships 220

12.4 Calculating the PMI requires experimental data on insect development and information from the crime scene 222

12.5 The evolving PMI: changing approaches and sources of error 227

Chapter review 230

Test your understanding 232

Notes 233

References cited 233

Supplemental reading 235

Additional resources 235

Chapter 13 Insect alterations of bloodstain evidence 237

Overview 237

The big picture 237

13.1 Bloodstains are not always what they appear to be at the crime scene 237

13.2 Science is the cornerstone of bloodstain pattern analyses 238

13.3 Crash course in bloodstain analyses 240

13.4 Insect activity can alter blood evidence 243

13.5 Insect feeding activity on bloodstains or fresh blood can yield regurgitate spots or transference 243

13.6 Digested blood is eliminated from insects as liquid feces or frass 245

13.7 Parasitic insects can confound blood evidence by leaving spot artifacts 246

Chapter review 246

Test your understanding 248

Notes 248

References cited 249

Supplemental reading 249

Additional resources 250

Chapter 14 Necrophagous and parasitic flies as indicators of neglect and abuse 251

Overview 251

The big picture 251

14.1 Parasitic and necrophagous flies can infest humans, pets, and livestock 252

14.2 Not all forensically important insects wait until death to feed 253

14.3 Chemoattraction of flies to the living does not necessarily differ from the odors of death 255

14.4 Necrophagous and parasitic flies display oviposition and development preferences on their vertebrate “hosts” 257

14.5 Larval myiasis can be fatal 258

Chapter review 261

Test your understanding 263

Notes 263

References cited 264

Supplemental reading 265

Additional resources 266

Chapter 15 Application of molecular methods to forensic entomology 267

Overview 267

The big picture 267

15.1 Molecular methods: living things can be defined by their DNA 267

15.2 Evidence collection: preserve DNA integrity 270

15.3 Molecular methods of species identification 270

15.4 DNA barcoding protocol 275

15.5 Problems encountered in barcoding projects 279

15.6 Gut content: victim and suspect identifications 280

15.7 Molecular methods and population genetics 281

15.8 Molecular methods: non-DNA based 282

15.9 Validating molecular methods for use as evidence 284

15.10 Future directions 284

Chapter review 285

Test your understanding 287

References cited 288

Supplemental reading 291

Additional resources 292

Chapter 16 Archaeoentomology: insects and archaeology 293

Overview 293

The big picture 293

16.1 Archaeoentomology is a new “old” discipline 293

16.2 Concepts and techniques from forensic entomology can be applied to archaeology 295

16.3 Ancient insects and food: connection to stored product entomology 296

16.4 Ancient insects as pests: beginnings of synanthropy and urban entomology 298

16.5 Ancient insects and mummies: revelations about past lives and civilizations 301

16.6 Forensic archaeoentomology: entomological investigations into extremely “cold” cases 304

Chapter review 304

Test your understanding 306

Notes 307

References cited 307

Supplemental reading 309

Additional resources 309

Chapter 17 Insects as weapons of war and threats to national security 311

Overview 311

The big picture 311

17.1 Terrorism and biological threats to national security are part of today’s world 312

17.2 Entomological weapons are not new ideas 314

17.3 Direct entomological threats to human populations are not all historical 316

17.4 Impending entomological threats to agriculture and food safety 318

17.5 Insect-borne diseases as new or renewed threats to human health 319

17.6 Insects can be used as tools for national security 321

Chapter review 324

Test your understanding 327

Notes 328

References cited 328

Supplemental reading 329

Additional resources 329

Chapter 18 Deadly insects 331

Overview 331

The big picture 331

18.1 Insects that bite, sting or secrete cause fear, loathing, and death 332

18.2 Insects that cause death 333

18.3 Human envenomation and intoxication by insect-derived toxins 338

18.4 Insects that injure humans rely on chemically diverse venoms and toxins 338

18.5 Non-insect arthropods that should scare you! 342

18.6 Implications of deadly insects for forensic entomology 345

Chapter review 346

Test your understanding 349

Notes 349

References cited 350

Supplemental reading 351

Additional resources 351

Appendix I Collection and preservation of calyptrate Diptera 353

Collecting adult flies 353

Collecting fly larvae 355

Mounting and preserving specimens (adult flies) 355

References cited 357

Resources and links 357

Appendix II Getting specimens identified 359

Morphological identification of specimens on your own 359

Identification of specimens (by systematic expert) 360

References cited 361

Resources and links 361

Appendix III Necrophagous fly life table references 363

Glossary 367

Index 377