A CHECKLIST OF FORENSICALLY IMPORTANT INSECT TAXA ON DECOMPOSING CARCASSES AND SUCCESSIONAL PATTERNS RELATED TO DECOMPOSITION AND SEASON IN MINNESOTA A THESIS SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY CORREY S. HILDEBRAND ROBIN E. THOMSON, ADVISOR IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE AUGUST 2019 Copyright © Correy Shearman Hildebrand ACKNOWLEDGEMENTS I would like to express my sincere gratitude to my major advisor, Dr. Robin Thomson, for providing me with the opportunity to pursue an advanced degree. I am forever grateful for the guidance and patience demonstrated by her throughout my graduate career. I would like to gratefully acknowledge the remaining members of my committee. I wish to thank Dr. Roger Moon for his much necessary tutelage of statistics and accumulated degree days, as well as his helping hand with field work. I am very thankful for the mentorship of Val Cervenka, who laid the path for my work in forensic entomology, and without her advice and experience I wouldn’t have this opportunity. This material is based upon work supported by the National Science Foundation under Grant Number CSBR 00052928, to Robin Thomson. I am grateful for funding received from the University of Minnesota Council of Graduate Students and Department of Entomology. I would also like to acknowledge the support of the Minnesota Agricultural Experiment Station. Dr. Ralph Holzenthal has been invaluable in both his taxonomic wisdom as well as his carpentry skills and for this I am most appreciative! Drs. Terry Whitworth, John Luhman and Roger Blahnik have also been most helpful in the identification of specimens and I would like to acknowledge their contributions to this project. Additionally, I would like to thank the following volunteers for their time and effort: Veronica Tonnell, Serenna Svanoe, Mathieu Nicklay, Calla Morrissey, Katelyn Bodin, and Sarah Wood. Additionally, a special thank you to Doug and Deb Manthei of Manthei Pig Farm in Elk River, Minnesota. I would like to thank my mother and father for their moral support. Despite possessing a limited understanding and tolerance of all subjects of entomology, they have been a shoulder to lean, and an ear to give. You’re a marvel, Ma. Dad, you’re my hero. I would also like to include a quick but meaningful bit of gratitude to my small group of life-long friends, who have endured many dry conversations regarding my research. Josh, Erika, LaRae, Andrea, Leslie, Kurt, and Thora—thank you for feigning interest in a subject that utterly bored and disgusted you. Lastly, I would like to thank my husband, Aaron, for his endless and tireless support. He has played the role of satellite for far too long and for that, I will always be indebted and forever grateful. i DEDICATION My thesis work is dedicated to Trent Reznor. Oh! And my husband. ii TABLE OF CONTENTS ACKNOWLEDGEMENTS ................................................................... i DEDICATION .................................................................................... ii TABLE OF CONTENTS .....................................................................iii LIST OF FIGURES ........................................................................... vi LIST OF TABLES ............................................................................. vii ABSTRACT ..................................................................................... viii CHAPTER I INTRODUCTION AND LITERATURE REVIEW ................................ 1 1.1 Introduction .................................................................... 1 1.2 Defining Forensic Entomology ....................................... 3 1.3 A Brief History of Forensic Entomology ........................... 3 1.4 Forensic Entomology Today ........................................... 5 1.5 Human Decomposition .................................................... 6 1.6 Biology of Calliphoridae ................................................ 10 1.7 Insect Succession ......................................................... 11 1.8 Faunal Surveys and Succession Studies ...................... 13 iii CHAPTER II CHECKLIST OF FORENSICALLY IMPORTANT INSECT TAXA ON DECOMPOSING PIG CARCASSES IN MINNESOTA ................... 19 2.1 Introduction .................................................................. 19 2.2 Materials and Methods .................................................. 19 2.2.1 Research Site and Study Plot ......................... 20 2.2.2 Carcasses ........................................................ 21 2.2.3 Carcass Sampling ............................................ 21 2.2.4 Specimen Identification and Preservation ........ 22 2.3 Results and Discussion ................................................. 23 2.3.1 Calliphoridae .................................................... 24 2.3.2 Non-Calliphoridae Diptera ................................ 30 2.3.3 Coleoptera ....................................................... 32 2.4 Conclusion .................................................................... 34 CHAPTER III DECOMPOSITION AND SEASONAL DISTRIBUTION ................... 36 3.1 Introduction .................................................................. 36 3.2 Materials and Methods ................................................. 36 3.3 Results and Discussion ................................................ 38 3.3.1 Decomposition ................................................ 38 3.3.2 Seasonal Distribution ...................................... 45 3.4 Conclusion .................................................................... 52 iv LITERATURE CITED ..................................................................... 55 APPENDIX A ................................................................................... 58 v LIST OF FIGURES Figure 3.1 July 2018 pig carcass in the first four stages of decomposition. University of Minnesota St. Paul campus dairy ............................ 37 vi LIST OF TABLES Table 1.1 Calliphoridae collected on decomposing carcasses throughout North America by region .............................................................. 14 Table 2.1 Dates of carcass placement. University of Minnesota St. Paul campus dairy, spring 2017 to fall 2018 ........................................ 22 Table 2.2 Sixty-four forensically important insect taxa on 11 decomposing pig carcasses. University of Minnesota St. Paul campus dairy, spring 2017 to fall 2018 .......................................................................... 25 Table 2.3 Calliphoridae collected on decomposing pig carcasses in North America by state or province including new results form 11 decomposing pig carcasses. University of Minnesota St. Paul campus dairy, spring 2017 to fall 2018 ........................................ 30 Table 3.1 Number of days each carcass spent in decomposition. University of Minnesota St. Paul campus dairy, spring 2017 to fall 2018 ......... 40 Table 3.2 Percentage of pig carcasses on which insect taxa occurred for each stage of decomposition. University of Minnesota St. Paul campus dairy, spring 2017 to fall 2018 ....................................................... 45 Table 3.3 Number of collection events of forensically important insect taxa on 11 decomposing pigs, grouped by season at time of collection. University of Minnesota St. Paul campus dairy, spring 2017 to fall 2018 ........................................................................................ 48 Table 3.4 Occurrence of adult Calliphoridae collected from 11 decomposing pig carcasses. University of Minnesota St. Paul campus dairy, spring 2017 to fall 2018 ................................................................ 50 Table 3.5 Occurrence of reared Calliphoridae collected from 11 decomposing pig carcasses. University of Minnesota St. Paul campus dairy, spring 2017 to fall 2018 ................................................................ 51 vii ABSTRACT Numerous studies in North America have focused on the entomofauna associated with decomposing pig carcasses. However, research is lacking in the upper Midwest region of the United States. This study establishes a reference checklist of forensically important insect taxa throughout stages of decomposition of a carcass and investigates these taxa in relation to both stage of decomposition and season in Minnesota. Eleven pig carcasses (Sus scrofa) were placed in the field at monthly intervals from May 2017 through September 2018 and were examined daily to collect both immature and adult insects. Collections were with aerial net, pitfall traps, and hand collection. Adult specimens were identified and preserved. A portion of calliphorid larvae were also reared to adult in the laboratory for identification and preservation. In total, 64 forensically important insect taxa were recorded, representing 14 families, and including 12 species of Calliphoridae. Phormia regina and Lucilia sericata were consistently abundant through temperate seasons. Calliphoridae dominated the early stages of decomposition, and Coleoptera increased in the later stages of decomposition. The results of this study will serve as a practical tool of geographic reference of forensically important insects for local law enforcement agencies and forensic entomologists investigating cases of unnatural death in Minnesota, and also will serve as a foundation for further succession research in the region. viii Chapter 1: Introduction and Literature Review