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Carrion Fly and Disease Vector Activity Associated with a Decomposing Corpse LTJG David England,MSC,USN Medicolegal Entomology Navy Entomology Center of.

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Presentation on theme: "Carrion Fly and Disease Vector Activity Associated with a Decomposing Corpse LTJG David England,MSC,USN Medicolegal Entomology Navy Entomology Center of."— Presentation transcript:

1 Carrion Fly and Disease Vector Activity Associated with a Decomposing Corpse LTJG David England,MSC,USN Medicolegal Entomology Navy Entomology Center of Excellence Naval Air Station Jacksonville, FL

2 Objectives 1.Basic Methods For Estimating Postmortem Interval 2.Oregon Decomposition And Insect Succession Model 3.Current Forensic Entomology Endeavors

3 AccumulatedDegreeDayHours Post Mortem Interval(PMI)

4 Estimation of PMI  Insect succession patterns  Insect life cycles  Influential variables Life Cycle Variables SuccessionPMI

5 Variables that influence PMI  Temperature  Season  Species  Death Scenario  Toxicology  Parasitoids & Predators

6 Insect Succession Succession of insects generally follows a similar pattern at the family level, but there are variations at the genus and species levels with respect to differing geographical locations Forensic entomology ‘works’ because succession is a very predictable and consistent event

7 Site Location Soap Creek Ranch, 18km NW of Corvallis

8 Animal Model  36 kg domestic pigs  Euthanasia method  Clothed  Caged  Human homicide scenario

9 Sampling Methods: Onsite & Laboratory  Temperature readings: ambient, carcass and maggot mass  Insect Sampling Sticky, Pitfall, Hand Sample and Net  One Pig Weighed Daily (Change in Mass)  Growth Chambers 22°C and 12 hours controlled light 22°C and 12 hours controlled light  Identifications - OSU Insect Collection

10 Stages Of Decomposition*  Fresh  Bloated  Active Decay  Advanced Decay  Dry Remains * Catts and Haskell, 1990

11 Fresh Stage  10 minutes PMI  Calliphoridae, species Lucilia illustris (Meigen)  Egg clusters: six hours PMI  Reared and identified

12 Calliphoridae Green bottle fly (Lucillia illustris) Photo:

13 Bloated Stage  Eight hours - Bloating  12 hours, bald-faced hornets (Dolichovespula maculata) (Linnaeus)  33 hours PMI: the green bottle fly eggs hatched  48 hrs: Staphylinidae appear

14 Staphylinidae Brown and gold rove (Ontholestes cingulatus) Hairy rove (Creopilus maxillosus Photo:

15 Active Decay Stage  72 hour PMI  Red-tailed flesh fly (Sarcophaga haemorrhoidalis)  Terrestrial isopods  Adult green bottle fly decreasing  Dermestidae, Silphidae, Histeridae

16 Advanced Decay Stage  120 hours: carcass began to desiccate  132 hours: third instar/post feeding maggots  147 hours: maggot mass exited carcass  Large predator/scavenger activity

17 Post Feeding Activities

18 Green bottle fly pupae

19 Dry Remains Stage  288 hrs PMI  Desiccated  Beetle Activity  No odor  Seasonal rain mid- October  25 days: scavengers  November: cages removed

20 November, 2005 Cage removed Cage removed April, months after cage removal

21 Decomposition Summary  Green bottle fly within 10 min  Ovipositing/egg cluster 6 hrs  33 hrs: first hatch  12 hrs: predators (hornet)  72 hrs: predators (beetles)  168 hrs: green bottle maggots left carcass  Jan. 1 st little evidence left; dead vegetation

22 Temperature Summary  Ambient temperatures (°C): Mean 20.8; Min. 9.03; Max  Maggot mass temperature (°C): Mean 30.9; Max (128 hrs.PMI)  Mean RH: 50%  Precipitation: none until Oct.

23 Rate of Decomposition % mass

24 Decomposition Rates Log of % mass

25 Linearized Regression Analysis _______________________________________________________________ Studies R² Slope (estimated) _______________________________________________________________ Grassberger: European Urban Habitat 1) May ) Aug Richards: Hawaiian Islands 1) 1877 m ) 1169 m ) 646 m Anderson: SW British Columbia 1) Carcass ) Carcass England: Corvallis, Oregon 1) Carcass

26 Summary  Regional Model  Standardized Analysis * * All slope values produced consistent results *Exponential decomposition rate that can be evaluated with linearization  Utilized In Further Research (geography, seasons, scenarios, etc.)

27 Current Forensic Entomology Endeavors  Provide Entomological Training For Naval Criminal Investigation Service  Georgia Research With Naval Criminal Investigation Service  Iraq Fly Samples

28 Acknowledgements Dr. Phil Rossignol Dr. Anne Rossignol Dr. Brian Croft Dr. Paul Jespersen CDR Szumlas Joyce Takyasu Clint Sexton

29 Questions and Discussion


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