Presentation on theme: "Also Included: Maggot Therapy and Taxidermy"— Presentation transcript:
1Also Included: Maggot Therapy and Taxidermy Forensic EntomologyAlso Included: Maggot Therapy and Taxidermy
2Forensic 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.
3The Most Common Application Relates to Death Investigations Determining PMI – postmortem intervalMovement of the corpseManner and cause of deathAssociation of suspects with the death sceneDetection of toxins or drugs through analysis of insect larvae
4Estimates of PMI Using Insects May Be Based On: Period of time for a given species to reach a particular stage of developmentComparisons of assemblages of insect fauna on corpse at time of examinationA combination of both above
5Most Important Environmental Factors in Corpse Decay* TemperatureAccess by insectsDepth of Burial* Based on study of decay rates of 150 human corpses at U. of Tenn.
6Ecological Roles of Insects in Decomposition Necrophages – species feeding on corpse tissue; mostly true flies and beetles; age determination (larval instar) important for PMIOmnivores – insects that feed both on the corpse and associated fauna; ants, wasps and some beetles; may alter rate of decompositionParasites and Predators – many beetles, true flies and wasps that attack immature fliesIncidentals – use the corpse as a resource extension; springtails, spiders, centipedes, some mites
7Five 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;
12Five Stages … 2Bloated 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
13Five Stages … 3Decay 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
17Five 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 beetlesin 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
19Five Stages … 5Dry 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
21Rat will be completely buried and eggs laid upon it. Female Carrion Beetle and Kangaroo RatRat will be completely buried and eggs laid upon it.
22Barriers to Decomposition and Irregular Decomposition Physical – soil, water, caskets, antermortem and postmotem injuriesChemical – embalming agent, insecticides, lime, etc.Climatic – heat, cold, wind, rainfallAnimals – bird, mice, rodents, canids, cats, etc.
23Maggot Therapy – Technically called Maggot Debridement Therapy or MDT Fly larvae are used to scavenge on dead tissue associated with a wound.Fly larvae excrement, termed allantoin has a high ammonia content which appears to serve as an antibiotic.
24Wounds on the Battlefield in World War II It has been noted by war surgeons that wounds incurred by troops in which fly larvae were feeding had much less gangrene and healed more quickly than wounds that were protected from flies …
25Phaenicia sericata – the green blow fly Phaenicia sericata – the green blow fly. This species feeds only on necrotic (decayed) tissue.
26Interesting 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.
27Maggots Feeding at Edge of an Ulcerating Wound on Foot
28Maggots Cleaning Up a Wound Associated with an Amputation
29Vertebrate Biology/Taxidermy – Skull and Skelton Preparation
36Dermestid Beetles Are Economic Pests and Will Scavenge on Anything Organic of Both Plant and Animal OriginDestroy woolen carpets, upholestry and rugsConsume insects on pins in museum and university collectionsStored furs, leather and skinsMeat, cheese and stored productsMaterials made of silk
37Dermestids are Beneficial in Terms of Their use in vertebrate skull/skeleton collectionsTheir forensic use as we have seen