Presentation on theme: "DO NOW: discuss with LP An insect flying into a girl's ear terrifies her. Her mother rushes the girl to the doctor, but he is unable to remove the insect."— Presentation transcript:
DO NOW: discuss with LP An insect flying into a girl's ear terrifies her. Her mother rushes the girl to the doctor, but he is unable to remove the insect. Suddenly, the mother has an idea. What is it?
SIGNAL After you hear the bell, you have 5 seconds to… … achieve silence … look me in the eyes … remain silent until I give instructions
S UGGESTED TEXT OF THE DAY Group MMS Mom Dad Bro Sis Frients Dog Cat Goldfish Parrot Ento mo logy
A SOLUTION The mother makes the daughter use a cow liver as a pillow.
Two things I learned about forensic entomology during this video… 1) 2) http://www.youtube.com/watch?v=C2YNmdPNG_A&list=PLRx mxOk3GDXL4gPVGhZsi7-_05xsX1IvY
W HAT IS F ORENSIC E NTOMOLOGY ? Forensic Entomology is the use of the insects and other arthropods that feed on decaying remains to aid legal investigations. Forensic Entomology is used to determine time since death This is called postmortem interval or PMI The time between death and corpse discovery Other uses include movement of the corpse manner and cause of death association of suspects with the death scene detection of toxins, drugs, or even the DNA of the victim through analysis of insect larvae.
I NSECT B IOLOGY Insects are the most diverse and abundant forms of life on earth. There are over a million described species- more than 2/3 of all known organisms There is more total biomass of insects than of humans. of humans. Insects undergo either incomplete or complete metamorphosis (Egg to larva to pupa to insect) Larva have a soft tubular body and look like worms. Fly species larvae are “maggots”
B RIEF H ISTORY Sung T’zu (1235) First reference to forensic entomology Bergeret (1855) Use forensic entomology to solve a case of a long-dead infant J.P. Megnin (1894) “La Faun des Cadavres: Application l’entomologie a la Medicine Legale” Hall 1948 Monograph on identification of blowflies Pekka Nuorteva of Finland (1970’s) Rekindled interest in the technique, published series of case histories Keh (1985), Smith (1986), Catts and Goff (1992) Textbooks and reviews
Insects as Evidence Forensic entomologists use their knowledge of insects and their life cycles and behaviors to give them clues about a crime. Most insects used in investigations are in two major orders: 1 – Flies (Diptera) 2 – Beetles (Coleoptera) Blow Fly Carrion Beetle
Examples of Diptera (Flies) Informational Source: http://naturalsciences.org/files/documents/csi_tg_overview.doc Images: Top Left - http://www.scienceinschool.org/repository/images/issue2forensic3_large.jpg, Middle-Left: http://forensicfact.files.wordpress.com/2008/04/blowfly053.jpg, Top Right - http://users.usachoice.net/~swb/forensics/P1.jpg, Bottom - http://www.deathonline.net/decomposition/corpse_fauna/flies/index.htm Flesh Fly (Sarcophagidae) S triped thorax Blow & Greenbottle Flies (Calliphoridae) Metallic thorax and abdomen House Fly (Muscidae) Cheese Skipper (Piophilidae) Early Stage Decomposition Late Stage Decomposition Life Cycle of a Calliphoridae Fly
Examples of Coleoptera (Beetles) Informational Source: http://naturalsciences.org/files/documents/csi_tg_overview.doc Images: http://www.cals.ncsu.edu/course/ent425/library/spotid/coleoptera/coleoptera.html & http://www.forensicflies.com/beetles.htm Carrion Beetles ( Silphidae) Adults & larvae feed on fly larvae Early to Late Stage Decomposition Late Stage Decomposition Rove Beetles (Staphylinidae) Predator of fly eggs Early Stage Decomposition Hide Beetles (Scarabidae) Usually the last to arrive Clown Beetles (Histeridae) Predator of fly eggs Ham & Checkered Beetles (Cleridae) Predator of flies & beetles; also feed on dead tissue Skin Beetles (Dermestidae) Feed on dried skin & tissues
Blow Fly Metamorphosis Blow flies are attracted to dead bodies and often arrive within minutes of the death of an animal. They have a complete life cycle that consists of egg, larva, pupa, and adult stages. It takes approximately 14-16 days from egg to adult depending on the temperatures and humidity levels at the location of the body. Adult Egg s Pupa 3 rd Instar Larva 2 nd Instar Larva 1 st Instar Larva
17 B LOWFLY L IFE C YCLE 1. <8 hours after death—blowfly eggs can be found in the moist, warm areas of a corpse 2. Within 20 hours—1 st of their 3 larva stages, 1 st Instar 3. 4 th or 5 th day—3 rd of their 3 larva stages, 3 rd Instar *The stages of larva can be determined by the number of spiracle slits at their posterior end
Last Friday, a hiker in Waco, Texas found a torso near the banks of the Brazos River in Cameron Park. A search was conducted by local law enforcement, and a pair of legs were found on Saturday.
Your job is to determine how long ago the person died based on insect evidence.
1) Use tweezers to obtain a sample. 2) Carefully carry your microscope to a lab table. 3) Analyze your sample. 4) Put your sample in the bucket and place your microscope back on the cart. 5) Thoroughly clean everything 6) Turn in all paperwork to your supervisor. THIS IS A SUMMATIVE GRADE.
LEFT PAGE REFLECTION 1) What did you like about this activity? 2) What could be improved about this activity? 3) What else do you want to know about forensic entomology?
G ENERAL L IFE CYCLE OF B EETLES A single female may lay from several dozen to several thousand eggs during her lifetime. Eggs can be laid singly or in clumps Larva feed voraciously – they can be predatory. The larval period varies between species but can be as long as several years. All beetle larvae go through several instars, which are the developmental stages between each molt. In many species the larvae simply increase in size with each successive instar as more food is consumed. In some cases, however, more dramatic changes occur. Beetle larvae pupate, and from this pupa emerges a fully formed, sexually mature adult beetle, or imago. Adults have an extremely variable lifespan, from weeks to years, depending on the species.
E COLOGY OF D ECOMPOSITION Necrophages - the first species feeding on corpse tissue. Includes rue flies (Diptera) and beetles (Coleoptera). Omnivores - species such as ants, wasps, and some beetles that feed on both the corpse and associated maggots. Large populations of ominvores may slow the rate of corpse’s decomposition by reducing populations of necrophagous species. Parasites and Predators - beetles, true flies and wasps that parasitize immature flies. Incidentals – pill bugs, spiders, mites, centipedes that use the corpse as an extension of their normal habitat
D ECAY R ATES A RE V ARIABLE Studies of decay rates of 150 human corpses at in the Anthropological Facility in Tennessee (The Body Farm) Most important environment factors in corpse decay: Temperature Access by insects Depth of burial Other Factors Chemical-- embalming agent, insecticides, lime, etc. Animals disrupting the corpse
T IME OF D EATH - I NSECTS Accumulated Degree Hours (ADH) 1. Immediately preserve some insects from the crime scene. 2. At the crime lab, raise some of the insects from the crime scene in the same conditions as those found at the crime scene. 3. Record the length of time for development under the specific conditions found at the crime scene. 4. Compare the insects raised at the crime lab to those found at the crime scene. 33 A “maggot milkshake” is a blended group of maggots that have fed on tissue and now are used to determine drug usage of the corpse.
M AJOR G ROUPS OF I NSECTS A SSOCIATED WITH C ADAVERS Flies Blowflies Flesh Flies House Flies Cheese Skippers Beetles Carrion Beetles Dermestids Scarab Beetles
B LUE B OTTLE F LIES (B LOW FLIES ) F AMILY NAME : C ALLIPHORIDAE Blowflies often are an attractive blue-green, metallic color, leading to the common English names, blue-bottles and green- bottles.Blowflies often are an attractive blue-green, metallic color, leading to the common English names, blue-bottles and green- bottles. They also come in a non- metallic, brown form, but all blowflies usually relatively large flies.They also come in a non- metallic, brown form, but all blowflies usually relatively large flies.
G REEN B OTTLE F LIES (B LOW FLIES ) F AMILY NAME : C ALLIPHORIDAE Blowflies can pick up faint traces of the odor of decay from up to 20 km away and lay their eggs in a suitable corpse. Blow flies are one of the first insects to arrive at a cadaver – they prefer fresh, moist flesh.
C OMMON H OUSE F LIES F AMILY NAME : M USCIDAE Adults are most common at corpses in the early stages of decomposition when the corpse is moist. The larvae are usually dung feeders.
F LESH F LIES F AMILY NAME : S ARCOPHAGIDAE Most flesh flies breed in dead animals, dung, or decaying material, but a few species lay their eggs in the open wounds of mammals; hence their common name.
C HEESE S KIPPER F AMILY NAME : P IOPHILIDAE Cheese flies are attracted to the cheesy odor which emanates from a corpse during the later stages of decomposition, particularly when the body is undergoing butyric fermentation. They are also common pests of cheeses and hams. Cheese Skippers have been found in coffins buried up to 3 m deep and in corpses up to 10 years old.
C ARRION B EETLES The first beetles arrive at a corpse soon after the body begins to putrefy. Flies, on the other hand, prefer fresher meat. In contrast to the flies, beetles have chewing mouthparts and can manage tougher foods than the semi-liquid material that fly larvae are so efficient at exploiting. Several beetle types make their living out of corpses. The early arrivals tend to be predatory adults that feed on fly larvae. Some of these species lay their eggs in the corpse, and the emerging larvae, which share their parents' powerful jaws, also feed on fly larvae.
C ARRION B EETLES F AMILY NAME : S ILPHILDAE There are over 200 species in this family, but the ones that eat dead flesh are those that belong to the subfamily Necrophorinae
M ORE ABOUT THE S ILPHID F AMIILY Silphids are large carrion beetles that feed on both carrion and fly larvae. Even though adults have been recorded feeding on carrion, they cannot survive on it alone, and die if they do not have access to maggots.
H ISTER BEETLES F AMILY NAME : H ISTERIDAE They are among the first beetles to arrive at carrion. They generally hide under a corpse during the daylight, and only become active at night when they enter the maggot-infested part of the corpse to capture and devour maggots. The adults feed on both the larvae and pupae of all species of blowfly. The adults lay their eggs in the corpse, and the larvae feed on blowfly pupae when they emerge.
S AP B EETLES F AMILY NAME : N ITIDULIDAE Nitidulids (sap beetles) are small to minute terrestrial beetles. They feed on tree sap, fungi, fruit juices, carrion, flowers or leaves.
R OVE B EETLES F AMILY NAME : S TAPHYLINIDAE They eat the fauna residing on and in a corpse Adults are early visitors to a corpse and they feed on larvae and eggs of all species of fly, including predatory fly larvae. They lay their eggs in the corpse, and the emerging larvae are also predators.
H IDE B EETLES F AMILY NAME : D ERMISTIDAE Late-arriving species tend to be specialist scavengers which feed on tougher parts like skin and tendons as the body dries out. The dominant late stage scavengers include the larvae of hide beetles (Dermestidae).
S CARAB B EETLES F AMILY S CARABAEIDAE Like the dermestids, scarab beetles arrive when the body is completely dry
H AM BEETLES (C HECKERED B EETLES ) F AMILY NAME : C LERIDAE Clerids are elongate beetles that often have a metallic sheen or are colored red or yellow. Both the larvae and the adults are predatory, feeding on other insects. The Ham beetle is common in the later stages of decomposition of a carcass. The larvae feed on dried fat and pupate inside the empty pupal cases of flies, after sealing the opening with silk.
C ARCASS BEETLES F AMILY NAME : T ROGIDAE Carcass beetles are large beetles with very thick exoskeletons and uniform dark coloration. They are among the last beetles to inhabit a carcass. They feed on dried remains such as skin and ligaments. Both adults and larvae feed on the carcass and the larvae live in vertical burrows underneath it when they are not foraging.