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Carrion Fly and Disease Vector Activity Associated with a Decomposing Corpse

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. Objectives. Basic Methods For Estimating Postmortem Interval

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Carrion Fly and Disease Vector Activity Associated with a Decomposing Corpse

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  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 • Basic Methods For Estimating Postmortem Interval • Oregon Decomposition And Insect Succession Model • Current Forensic Entomology Endeavors

  3. Accumulated Degree Day Hours Post Mortem Interval (PMI)

  4. Estimation of PMI • Insect succession patterns • Insect life cycles • Influential variables PMI

  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 • 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. CalliphoridaeGreen bottle fly (Lucillia illustris) Photo: http://bugguide.net

  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 Hairy rove (Creopilus maxillosus Photo: http://bugguide.net Brown and gold rove (Ontholestes cingulatus)

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

  20. November, 2005 Cage removed April, 2006 6 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. 1st little evidence left; dead vegetation

  22. Temperature Summary • Ambient temperatures (°C): Mean 20.8; Min. 9.03; Max. 34.9 • Maggot mass temperature (°C): Mean 30.9; Max. 50.7 (128 hrs.PMI) • Mean RH: 50% • Precipitation: none until Oct.

  23. Rate of Decomposition % mass

  24. Decomposition Rates Log of % mass

  25. 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.)

  26. Current Forensic Entomology Endeavors • Provide Entomological Training For Naval Criminal Investigation Service • Georgia Research With Naval Criminal Investigation Service • Iraq Fly Samples

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

  28. Questions and Discussion

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