forensics lecture 6- bugs to bacteria Flashcards
what is entomology?
-From the ancient Greek – entomon and -logia study of
-A branch of zoology.
-Study of insects – so those from the phylum arthopoda, with an exoskeleton, and no vertebrate.
-The largest group of any animal – more than 1million species have been described.
Insects live in nearly every conceivable environment and have done from the last 350 million years.
Entomology is crucial to our understanding of evolution, biodiversity, agriculture and human disease, but also forensics.
what is forensic entomology?
-the use of insects (and their larvae) and/or arthropods to aid in legal investigations
-primarily use to aid in unnatural death investigations
also used to
-Detect drugs and poisons
- Determine location of an incident
-Find the presence and time of the infliction of wounds
what are the 3 areas of application?
1- insects that inhabit human remains
2- insects that damage structures
3- infestation of foods
what is the post mortem interval?
the interval between time of death and post mortem exam
what are the methods used to determine PMI?
-Algor Mortis
-Livor Mortis
-Rigor Mortis
-Changes in fluid of the eye
-Stomach and bowel contents
-Decomposition changes
-Insect colonization
-Circumstantial evidence
how do insects provide evidence during post mortem interval?
-Season of death. -succession
-Changes in location after death – urban/rural
-Circumstances surrounding the death
-Body on the surface for a while before burial?
-Aquatic insects? Season and conditions under which the body came to be in water
-Toxicology
how are insects used as evidence in ecological concepts?
-Different species go through development in a predicted pattern.
-Developmental time is temperature dependent.
-Succession.
why are insects useful?
-metamorphosis
-feeding strategies
-sophisticated behaviour
-small size
-chitin
-wings
-life cycles
how are invertebrates used as forensic indicators?
1- invertebrates attracted to dead bodies eg detritivores
2- invertebrates that leave dead bodies
3- invertebrates that leave dead bodies
4- invertebrates as a cause of death
what is the entomology succession?
1- blowflies
2- flesh flies
3- burying/ histerid beetle
4- house flies
5- dermestid beetles
what insects colonise a corpse?
blue bottle fly
what is the life cycle of a blow fly?
-Adult female blowflies arrive within minutes to lay eggs on a body (up to 300 eggs) in wounds and natural openings
-Within 24 hours eggs hatch in to 1st instar larvae.
-Feed –moult to 2nd instar larvae
-Feed – moult to 3rd stage maggots
-Feed – moult to prepupae larvae move away from the body and no feeding
-Moult to pupae then final stage of moult to adult
why are microorganisms important?
- advances in technology
- awareness of dangers of pathogenic microbes
- increase in individuals/ groups threatening to release pathogens maliciously and cause distres
what is the relationship between microorganisms and decomposition?
-We are host to a large number of microbes.
-Bacteria are important to the decay process.
-Environmental factors affect decomposition
Dry/frozen environmental slow down decomposition
Warm and moist environmental speed up decomposition.
-Time since death – can we use microorganisms for PMI? Not yet.
how are microorganisms used as identification tools?
-Soil microbes
-Saliva microbes
-Geographical origin
-Microbial infection transfer
-Food poisoning
