HOSA: Forensic entomology

Requirements to become a forensic entomologist

Bachelor's degree of science in biology, zoology, or entomology

Followed by a master's degree and doctorate in entomology

Medicological entomology

Use of entomology in death/abuse inestigations

Entomology

The scientific study of insects

Forensic entomology

The study of insects as they pertain to legal issues

Published writing about forensic entomology dates back to...

10th/13th centuries, used in ancient Chinese murder investigations

Jean-Pierre Megnon

Wrote La Fauna des Cadavres, the first serious book on forensic entomology

1966

American Board of Forensic Entomology is led by Dr. Paul Cotts and Dr. Lee Geff

2002

First North American Forensic Entomology Association meeting held

End of 19th century

First entomological research conducted in Quebec

Dipteran larvae

Also known as maggots, are the larvae of blowflies

Why blowflies are used to estimate time of death

They will arrive very quickly to a dead body

Blowflies are only active during which time of the day?

Daytime

1st instar

5mm long

Appears after 1.8 days

Stage lasts 20 hours long

Egg

2mm long

Appears soon after death

Stage lasts 8 hrs long

2nd instar

10mm long

Appears 2.5 days later

Stage lasts 15-20 hours

Dark crop visible through skin

3rd instar

17mm long

Appears 4-5 days later

Stage lasts 36-56 hours

Insects will consume large amount of tissue during this time

Pre-pupa

9mm long

Appears 8-12 days later

Stage lasts 86-120 hours long

Early+late pupa

9mm long

Appears 18-24 days later

Stage lasts 6-12 days long

Adult

Size varies

Appears 21-25 days later

Stage lasts several weeks

Distinguishing larvae by number of slits

1st instar larvae have one V-shaped slit

2nd instar larvae have 2 slits

3rd instar larvae have 3 slits

Accumulated degree hours (ADH)

The number of hours at an adjusted average temperature it takes for an insect species to develop to a given stage

Successional colonization

Process by which a body is colonized by a series of insects spaced out over time

Puparium

The hard pupal case of the insect pupa

Insect larvae are attracted to which two gases of decomposition?

Putrescine and cadaverine

Other uses for entomology in death investigations

Indicating whether body has moved

Indicating whether body was disturbed

Indicating position of wounds

When consuming a body, larvae will first settle in...

Wounds, then natural orifices (nose, mouth, etc) that have a membrane layer

Entomotoxicology

The study of drugs, poisons, and metabolites found in insects

Drugs can affect insect development by...

Slowing it down or speeding it up

DNA identification using insects

1. Using DNA to find species of insect when evidence is too damaged

2. Using DNA to identify victim by testing DNA of partially digested tissue inside crop of insect

Crop

"Gut", stores food

Frass

Solid wastes excreted by insect larvae

Myiasis

Parasitic infestation of living vertebrate tissue by larval flies

Myiasis primarily occurs in...

Very young children, old adults, and temporarily/permanently incapacitated people in need of a caregiver

In which part of a cocaine user's body will larvae converge?

Nose, since cocaine damages septum

Maggot debridement therapy (MDT)

The purposeful use of maggots on living patients to remove dead tissue

Dr. William Baer

Used MDT to treat soldiers in WW1 who were susceptible to infection in trench warfare

Used MDT to treat osteomyelitis, a deep bone infection

Dr. Ronald Sherman

Discovered that maggots also secrete antibodies/allantoin

Simulate granulation, the production of new tissue

Secrete ammonia, which alkalizes wound (bacteria prefer acidic environment)

Lack of insects may result from...

Too low of a temperature

Too early in the year

Body was very recently killed

Body was stored in inaccessible location

Rings of death

Carcass of a poisoned animal is fed on by other animals, causing these scavengers to get sick and die, and are fed by other other scavengers, creating noticeable rings of death

The age of the oldest insect evidence relating to a corpse is used to calculate...

The minimum time of death

Forensic entomology is important because...

The time of death is of value to grieving family members

It may have legal implications

Forensic entomology allows for the determination of...

Time since death

Whether body has moved or disturbed

Presence of wound sites

Whether deceased was poisoned/drugged

Length of time of neglect in living victims

Two methods of estimating time of death using forensic entomology

Predictable development of larval Diptera

Successional colonization of body with different species

Although unnoticeable to humans, dead bodies give off...

A variety of chemical cues such as odours, which can be detected by blowflies

Diurnal

Active during the day

As temperature increases, insect larvae develop __________ quickly

More

Factors taken into account when estimating time of death

Oldest insects present

Temperature data

Species of insect

Development data (how long it takes for an insect to reach a certain stage under the present environmental conditions)

Successional colonization is used when...

The time of death is much lengthier than could be determined using Diptera larvae development

It is the _______________ who identifies the wound site and what weapon may have caused it

Forensic pathologist

Bioaccumulate

The accumulation of toxic chemicals in an organism, often the chemicals are stored in fatty tissues

Puparial

A stage in the lifecycle of an insect that follows the larval stage

Carrion

The decaying flesh of dead animals