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Forensic Entomology

Forensic Entomology Relies Strongly on the Following Ecological Concepts. Developmental time is temperature dependant at the microhabitat level. Ecological succession

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Forensic Entomology

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    1. Forensic Entomology Also Included: Maggot Therapy and Taxidermy

    2. Forensic Entomology Relies Strongly on the Following Ecological Concepts Developmental time is temperature dependant at the microhabitat level. Ecological succession – A corpse will be invaded by a series of different species or insect groups over time. Each species or group changes the microenvironment through its activities which makes it attractive to new waves of organisms and so on.

    3. Forensic Entomology is Involved With Arthropod Involvement in Events Surrounding Felonies Violent Crimes murder, suicide and rape physical abuse contraband trafficking

    4. The Most Common Application Relates to Death Investigations Determining PMI – postmortem interval Movement of the corpse Manner and cause of death Association of suspects with the death scene Detection of toxins or drugs through analysis of insect larvae

    5. Estimates of PMI Using Insects May Be Based On: Period of time for a given species to reach a particular stage of development Comparisons of assemblages of insect fauna on corpse at time of examination A combination of both above

    6. Most Important Environmental Factors in Corpse Decay* Temperature Access by insects Depth of Burial * Based on study of decay rates of 150 human corpses at U. of Tenn.

    7. Rcological Roles of Insects in Decompositon Necrophages – species feeding on corpse tissue; mostly true flies and beetles; age determination (larval instar) important for PMI Omnivores – insects that feed both on the corpse and associated fauna; ants, wasps and some beetles; may alter rate of decomposition Parasites and Predators – many beetles, true flies and wasps that attack immature flies Incidentals – use the corpse as a resource extension; springtails, spiders, centipedes, some mites

    8. Five Stages of Human Decomposition Have Been Recognized -1 Fresh Stage (Days 1-2) – From moment of death to first sign of bloating; flesh flies, blow flies, ants eating fly eggs and predatory wasps;

    9. Flesh Flies – 2 Species

    10. Two Blowfly Species

    11. Blowfly Larvae

    13. Five Stages … 2 Bloated stage (Days 2-6) – putrefaction begins; gases produced by anaerobic bacteria; considerable bloating; seepage of fluids; adult and larval blowflies attracted in large numbers to seepage; soil fauna moves away due to wetness of earth; ants and other species of flies prey on maggots

    14. Five Stages … 3 Decay Stage (Days 5-11) – Abdominal wall is broken and carcass deflates; adult flies begin to leave but great masses of maggots remain and feed; carcass will begin to dry and beetles begin feeding on drier tissue; flies start to pupate; predatory beetles such as rove and hister beetles are attracted

    16. Hister Beetles Prey on Blowfly Larvae

    17. Rove Beetles – 2 Species

    18. Five Stages … 4 Postdecay Stage (Days 10-25) in dry habitats - remains consist of dry skin, cartilage and bones; site for dermestid beetles, histerids, fly pupae, immature and adult rove beetles in wet habitats – large quantities of wet, viscous material (byproducts of decomposition) found in soil under the remains; site for adult and immature moth flies, rove beetles

    19. Dermestid Beetles – Adult and Larvae

    20. Five Stages … 5 Dry Stage (Days 25+) – Mainly bone and hair is all that remains; odor is primarily that of soil and litter; some dermestids, fly pupae, immature and adult rove beetles, normal soil fauna consisting of mites, etc. start to return; this stage could last for several months to years

    21. Carrion Beetles – 2 Species

    23. Barriers to Decomposition and Irregular Decomposition Physical – soil, water, caskets, antermortem and postmotem injuries Chemical – embalming agent, insecticides, lime, etc. Climatic – heat, cold, wind, rainfall Animals – bird, mice, rodents, canids, cats, etc.

    24. Maggot Therapy – Technically called Maggot Debridement Therapy or MDT

    25. Wounds on the Battlefield in World War II

    27. Interesting and True … Maggot therapy is much more commonly used in Great Britain and Europe than in the U.S. There have been about 25,000 treatments in Great Britain since 1995. Ronald Sherman, M.D. is the pioneer of maggot therapy in the U.S. He is located at U. of Calif., Irvine.

    37. Dermestid Beetles Are Economic Pests and Will Scavenge on Anything Organic of Both Plant and Animal Origin Destroy woolen carpets, upholestry and rugs Consume insects on pins in museum and university collections Stored furs, leather and skins Meat, cheese and stored products Materials made of silk

    38. Dermestids are Beneficial in Terms of Their use in vertebrate skull/skeleton collections Their forensic use as we have seen

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