«Entomotoxicological and Thermal Factors Affecting the Development of Forensically Important Flies Derek Reed Monthei Dissertation submitted to the ...»
Entomotoxicological and Thermal Factors Affecting the Development of Forensically
Derek Reed Monthei
Dissertation submitted to the Faculty of Virginia Polytechnic Institute and State University in
partial fulfillment of the requirements for the degree of
Doctor of Philosophy
Dr. Richard D. Fell, Chairperson
Dr. Carlyle C. Brewster
Dr. Sally Paulson
Dr. Kevin Pelzer
Dr. George S. Behonick
Dr. Michelle R. Peace
February 6th, 2009
Blacksburg, Virginia Tech Keywords: Forensic Entomology, Entomotoxicology, Degree-days, Postmortem Interval Copyright 2009, Derek Reed Monthei Entomotoxicological and Thermal Factors Affecting the Development of Forensically Important Flies Derek Reed Monthei Abstract Studies were conducted on the effects of alcohol and opioids on the development of forensically important flies. In addition different methods of degree-day calculations and development thresholds were used to determine the effects on PMI estimates. The first study determined the effects of ethanol on the development of Phormia regina in vitro. Ground pork loin was treated with a 1, 5, or 10% ethanol solution to give an equivalent Blood Alcohol Concentration (BAC) of 0.01, 0.04, and 0.8 % w/v. A significant difference in the time for second instars’ to complete the stage was seen between the 1% treated and control. Significant differences were also found among pupal and adult weights between all treatments and the control. A significant difference was shown between growth curves of the 5% treated and control for third instar larvae using the Kolmogorov-Smirnov test.
The ethanol content of Phormia regina in migrating third instar larvae that fed on treated meat was examined using headspace-gas chromatography (HSGC). All larvae had a content of 0.01% w/v, including the control.
The effects of ante-mortem injection of oxycodone in pigs were examined with respect to insect succession patterns and the development rates of Phormia regina. Pigs were given a subcutaneous injection of oxycodone hydrochloride (3 mg/kg by weight) and antemortem blood samples were collected prior to and following drug injection. Shortly after death the carcasses were placed at an open field site and allowed to decompose in a field cage. Insect samples were collected from carcasses for seven days post-mortem and the collected data were used to develop occurrence matrices. The Simple Matching Coefficient showed that successional patterns were similar between treated and untreated animals. Loin and liver from the carcasses were used as rearing media for in vitro development studies of Phormia regina. Kolmogorov-Smirnov test showed that third instar P. regina maggots from treated loin tissue were significantly longer in length than maggots feeding on untreated loin tissue. A significant difference in time was found among larvae on loin for the time from eclosion to completion of the second instar. Significant differences were seen in the weight of adults reared on liver and loin. A chi-square for homogeneity showed that adults were biased towards males (2:1) from untreated loin tissue.
A final study compared weather data sources, Accumulated Degree-Day (ADD) methods, and postmortem interval (PMI) estimations based on threshold and developmental data source.
Four pigs were used for statistical comparisons. Pigs were taken to a test site and allowed to decompose in an experimental cage. Probes recorded ambient temperatures and body temperatures. Maggot sampling was completed every day for each pig. A three way factorial linear fit model was used to test for statistical differences. Significant differences were seen in the calculated ADD based on probe location and the development threshold used. The ADD calculated from local weather station locations: Kentland Farm, Moore Farm, and Blacksburg Airport were also compared. A significant difference in ADD was found in the main effects among locations (Airport 44.1 ADD, Kentland 37.5 ADD, Moore 48.6 ADD), as well as among the thresholds used (10,12.2, and 14°C). Different PMI estimations also resulted when using development data from different development studies on Phormia regina.
iii Acknowledgements I would like to thank my advisor, Dr. Richard D. Fell for his ideas, support, and encouragement.
I would also like to thank all the members of my committee, Dr. Carlyle Brewster, Dr.
Sally Paulson, Dr. Kevin Pelzer, Dr. George Behonick, and Dr. Michelle Peace for their input, help, ideas, and direction in my studies.
I would like to thank Scotty Bolling for helping me construct my test cages.
I would like to thank Cindy Wood and Mike Ashby (Swine Center at Virginia Tech) for providing and housing the pigs used in the studies. I would also like thank Tara Valouch, David Burrows, Dr. James Kuhlman, Geraldine Magnin-Bissel, Dr. Blair Meldrum, Xiaohua Wu, Elizabeth Watson, and Jean Cobb for assistance with laboratory analysis. This project was reviewed and approved by the Animal Care Committee at Virginia Tech. Financial assistance provided by the Forensic Sciences Foundation from an Acorn Research grant as well as the Graduate Research Development Project Grant from the Graduate School at Virginia Tech.
I also appreciate and am grateful to many of the faculty, staff, and students in the Virginia Tech Department of Entomology for their assistance, support, and friendship. Special thanks to Dr. Don Mullins and Sandra Gabbert for all the supplies I borrowed and their time assisting me, Kathy Shelor and Sarah Kenley for being patient with me all the times I needed their assistance, to Dr. Reese Voshell for not only being a good running buddy, but for his encouragement and mentoring over the years, and to the many graduate students I have met over the years who provided support and friendship.
Finally, I would like to express my gratitude to my mother, Teri Wallis, who provided unwavering support, let me pursue my goals, read over many of my papers, and provided a great deal of financial assistance over the years.
1. INTRODUCTION____________________________________________________ 1
2. LITERATURE REVIEW _____________________________________________ 4
2.1. PMI AND FLY DEVELOPMENT _________________________________________4 2.1.1. Methods for Determining ADH and ADD_____________________________________ 6 2.1.2. Factors that Influence Carrion Insect Development __________________________7
2.2. PHORMIA REGINA____________________________________________________ 10
2.3. SUCCESSION _________________________________________________________ 11
2.4. ENTOMOTOXICOLOGY _______________________________________________14 2.4.1. Oxycodone (Oxycontin®) ___________________________________________________ 18 2.4.2. Ethanol___________________________________________________________________ 23
3. EFFECT OF ETHANOL TREATED TISSUE ON THE DEVELOPMENT OFPHORMIA REGINA IN VITRO _________________________________________ 26
3.1. INTRODUCTION ______________________________________________________26
3.2. MATERIALS AND METHODS __________________________________________26
3.3. RESULTS _____________________________________________________________30
3.4 DISCUSSION __________________________________________________________ 31
4. THE EFFECTS OF ANTEMORTEM INJECTION OF OXYCODONE ON INSECT
SUCCESSIONAL PATTERNS AND DEVELOPMENT OF PHORMIA REGINA(DIPTERA: CALLIPHORIDAE)_________________________________________ 45
4.1. INTRODUCTION ______________________________________________________45
4.2. MATERIALS AND METHODS __________________________________________47 4.2.1. Animals and Oxycodone Dosing ____________________________________________ 47 4.2.2. Insect Succession___________________________________________________________ 49 4.2.3. Development Study ________________________________________________________ 50 4.2.4. Data and Statistical Analysis____________________________________________ 51
5. COMPARISON OF THERMAL FACTORS AND PMI ESTIMATES USINGFORENSICALLY IMPORTANT FLIES _________________________________ 73
5.1. INTRODUCTION ______________________________________________________73 v
5.2. MATERIALS AND METHODS __________________________________________75 5.2.1. Study Site _________________________________________________________________ 75 5.2.2. Animals and Cages_________________________________________________________ 75 5.2.3. Sampling Protocol _________________________________________________________ 77 5.2.4. Statistical Comparisons _____________________________________________________ 77
5.3. RESULTS____________________________________________________________ 79
5.4. DISCUSSION __________________________________________________________80
6. SUMMARY ________________________________________________________ 92
7. REFERENCES _____________________________________________________ 96
Figure 3.1: Evaporation curves for concentrations of ethanol in ground loin tissue over a five day period for a control (A), 1% ethanol solution (B), 5% ethanol solution (C), and 10% ethanol solution (D)…………………………………………………………………….
..36 Figure 3.2: Pupal weights (mg) (Mean ± SE) from larvae that fed on ethanol-treated and untreated pork loin tissue.
Larvae and pupae were reared on a 24:0 (L:D) cycle at 23°C.
A significant difference in pupal weight was found between the control (A) and the treated groups (B). N = 155 pupae for control, 154 for 1%, 226 for 5%, and 255 for 10%....……………………………………………………………………………………39 Figure 3.3: Adult weights (mg) (Mean ± SE) from larvae that fed on ethanol-treated and untreated pork loin tissue.
Larvae and pupae were reared on a 24:0 (L:D) cycle at 23°C.
A significant difference in adult weight was found between the control (A) and the treated groups (B). N = 154 adults for the control, 215 for 1%, 215 for 5%, and 337 for 10%
Figure 3.4: Lengths of maggots feeding on either a 1% (A), 5% (B), or 10% (C) ethanol-treated loin tissue or untreated (D) tissue.
Larvae were reared on a 24:0 (L:D) cycle at 23°C.
Four maggots were sampled every 8 hours from all treatments and the control. Maggot lengths were measured. N= 823 larvae for 1%, 860 for 5%, 1146 for 10% and 902 for the control……………………………………………………………………………………41 Figure 3.5: Fitted curves of lengths of maggots feeding on tissue from either 1%, 5%, 10% ethanol-treated and untreated loin tissue.
A second order polynomial was used as the fitted curve equation. All treatment curves were compared to the control curve..……...43 Figure 3.6: The percentage of males and females that emerged from the pupae of larvae that fed on ethanol-treated or untreated pork loin. N = 154 adult flies for Control, 215 for 1%, 215 for 5%, and 337 for 10% ……………………………………………………………44 Figure 4.1: Succession Diagram for Oxycodone-treated and Untreated pig carcasses during 7 day sampling intervals in summer 2006 in Blacksburg, VA. Stage of decomposition are shown and are (A) Fresh, (B) Bloat, (C) Active Decay, and (D) Advanced Decay……..66 Figure 4.2: Succession Diagram for Oxycodone-treated and Untreated pig carcasses during 7 day sampling intervals in summer 2007 in Blacksburg, VA. Stage of decomposition are shown and are (A) Fresh, (B) Bloat, (C) Active Decay, and (D) Advanced Decay……..67 Figure 4.3: Lengths of maggots feeding on either (A) oxycodone-treated loin tissue, (B) untreated loin tissue, (C) oxycodone-treated liver tissue, or (D) untreated liver tissue.
Larvae were reared on a 24:0 (L:D) cycle at 23°C. Four maggots were sampled every eight hours from all treatments and the control. Maggot lengths were measured. A second order polynomial was used as the fitted curve equation. N= 670 larvae for treated loin, 242 for untreated loin, 358 for treated liver and 96, for the untreated liver……………
Figure 4.4: Fitted curves of lengths of maggots feeding on tissue from oxycodone-treated and untreated (A) loin and (B) liver tissue.