Forensic Entomology

Overview of presentation: 1.What is forensic entomology? 2.Medicocriminal entomology. 3. How long has a particular individual been dead? A. Developmental times of insects. B. Insect succession. 4. Description of a project being conducted at ASU.

The study of insects and other arthropods to legal issues. Broad field. It can be divided in three subfields: 1. Urban Forensic Entomology 2. Stored-product Forensic Entomology 3. Medicocriminal Entomology What is Forensic Entomology?

Medicocriminal entomology usually involves: 1. The intrigue surrounding human or animal death. 2. The decay process. 3. Detective work necessary to bring perpetrators to trial.

A typical question posed to a medicocriminal entomologist: How long has a particular individual been dead? Estimates of time a decedent has been dead “PMI” = Postmortem Interval. Involves application of the temperature-dependent development of insects.

One important biological phenomenon that occurs on cadavers are a succession of organisms that thrive on the different parts. 1.Flies lay eggs usually within the first 24 hours 2.Predatory rove beetles or parasites that feed on maggots will have to wait until the blow flies arrive and lay their eggs. 3.Beetles that specialize on bone, will have to wait until bone is exposed. The succession on cadavers happens in a fairly predictable sequence and can be used in estimating time of death if the body has been lying around for some time. Insect Succession

Show: YouTube: Maggots feast on animal carcass

Commonly called flies. Over 86,000 known species, over 16,000 occur in North America. One of the largest insect orders. Found in almost every habitat. Complete metamorphosis. Body characteristics: One pair of wings. Second pair of wings reduced to knob-like organs called HALTERES (used to stabilize flight). Compound eyes. Mouthparts vary (sponging, piercing, cutting- sponging) ORDER DIPTERA

Flies associated with carrion have SPONGING mouthparts Pseudotrachea

The Life Cycle of a Fly Larvae 3 instars Prepupal stage Pupae Adults Exact time depends on temperature and moisture

Pupae are cylindrical. Posterior spiracles also present (used for identification).

Developmental Data on Blow Flies and Flesh Flies 27°C and 50% humidity SpeciesEgg (Hrs) 1 st instar (Hrs) 2 nd instar (Hrs) 3 rd instar (Hrs) Prepupa (Hrs) Pupa (Days) Sarcophaga cooley S. shermani S. bullata Phormia regina Protophormia terranovae Lucilia sericata Eucalliphora lilaea Cynomyopsis cadaverina Calliphora vomitoria C. vicina C. terranovae

YouTube: “Maggots feast on animal carcass” Extremely large family of medium-sized flies. ~1,000 spp., found worldwide. Along with sarcophagid and muscid flies, the most important species that provide information relating to accurate estimation of the postmortem interval. Attracted to carrion and excrement, with some exploiting open wounds. First to arrive at a crime scene. Blow Flies (Family Calliphoridae)

Black Scavenger Flies (Family Sepsidae) Worldwide in distribution with at least 240 spp. Adults are small, shining black, purple, or red flies. No more than 3.5 mm in length. Head is noticeably rounded. There is a constriction at the base of the abdomen. Behavior: Flick their wings outward as they walk (“waggle flies”).

Largest order containing a third of all known insects (300,000 spp.). 30,000 spp. found in N. America. Complete metamorphosis (egg, larvae, pupae, adult). Characteristics: ELYTRA – Front wings hard; covers and protects the hind wings (membranous) that are used for flight. Adults: Chewing mouthparts Most can fly Feeding habits vary: Predacious, Scavengers, Herbivores Beetles (Order Coleoptera)

Carrion Beetles, Family Silphidae Large family, nearly worldwide in distribution. 1,500 spp. worldwide; 46 spp. in N. America. Medium sized to large beetles (10 to 35 mm). Antennae are clubbed. Elytra are often short and leave several abdominal segments exposed. Body is usually black, marked with orange, yellow or red patches.

Larvae vary in size and shape. Generally 15 to 30 mm long. Most are flattened. All larvae are capable of mobility.

Clown Beetles, Family Histeridae Large family with over 3,000 spp. 500 spp. in North America. Small, seldom larger than 10 mm in length. Round bodies and very shiny. Elytra are short and squared at the apex. Last two abdominal segments are exposed. Antennae: Elbowed and clubbed.

Clown beetles are very common on carrion and excrement (found on fungi and decaying vegetable matter). On a carcass, tend to be concealed in the soil underneath the body during the daylight hours. Most active at night. Both adults and larvae are predacious feeding on maggots, fly pupae and dermestid larvae. When collected, must be separated from other insects.

Skin Beetles, Leather Beetles, Hide Beetles, Carpet Beetles & Larder Beetles, Family Dermestidae Given their names according to their food preferences. Worldwide in distribution with over 500 spp. 123 spp. found throughout North America. Small beetles ranging from 2 to 12 mm in length. Oval in shape, covered with scales (many colorful patterns). Feed on various types of dried animal tissue.

Larvae: Range from 5 to 15 mm Usually covered with long tufts of dense hair Adults Pupa Larva

Approximate duration of each stage of decomposition (in days) of pig carrion in sunny and shaded areas. Advanced Decay Decay Bloat Fresh Sun Shade Time Since Death (Days)

Time Blow fly larvae Rove beetle adults Hister beetles adults Parasitic wasps Rove beetle larvae Hister beetle larvae Dermestid adults Dermestid larvae Days mons. 6-9 mons mons. Insect Succession During One Year

Occurrence Matrix FamilyGenus/Species CalliphoridaeLucilia illustris A AA/L Sarcophagidae Phormia regina Cochliomya macellaria Chrysomya rufifacies Protocalliphora sp. Opsodexia sp. Phaenicia caprina Species 1 A AA AAA A AAAAA AAAAAA A A/L L A A/L A A A A A A A A A A A L A L A A A A A A Drosophilidae Species 2 Species 3 A AA A AAAA ChloropidaeSpecies 1 Species 2 A A A AA Sepsidae Muscidae Piophilidae Sepsis sp. Musca domestica Species 2 Protopiophila latipes AA AAA A AA AA A A AA A DolichopodidaeSciapus sp. A Encyridae Histeridae Tachinaephagus zealandicus Species A A LALA A A SilphidaeSpecies 1 L Trogidae Staphylinidae Cleridae Dermestidae Carabidae Omorgus sp. Necrobia Dermestes AAA AAA A A A A A L AA L AA Time since Death (Days) A = Adult L = Larva

Objectives: To examine insect succession on chickens that have been placed in a field at the ASU farm complex. Students were responsible for designing and doing the experiment. An Easy Science Project For Students

This experiment was conducted from 18 September – 12 October Dead chickens were donated from a poultry producer in the area. Four chickens were used in this experiment (weighed 8-10 lbs). Chickens were placed in cages to prevent scavenging by other animals. Cages could be opened from the side and top for easy access. Materials and Methods

A rock was placed on each cage to prevent the cage from being moved by predators. Two cages were placed next to trees. Two cages were placed in a more open environment. Vegetation around the cages was identified. The amount of sun exposure during the day was also estimated for each cage.

Insects were collected on a daily basis for the first two weeks of the study. After two weeks, insects were collected every other day. Insect collecting techniques used: Aerial nets Forceps Hands Collecting jars Vials with alcohol Insects will be identified to species.

Insects Collected Blow flies – Adults and larvae

Ants Rove beetles Flesh flies Sepsis sp. Dermestidae

Forensic Entomology Little research on forensic entomology in AR Develop a hypothesis Design the experiment Test the hypothesis Analyze the results Formulate conclusions