Forensic Entomology Exam 2

Ch 5,6,7,9,3

the arrival and departure of insect fauna at carrion is fairly unpredictable

True or False

False

the attractiveness of the body to specific fauna …. with the progression of decay

changes

each biogeographical area has its own specialist carrion fauna, but the broad …. of cadaver specialists are similar worldwide

taxonomic groups

the common animal used in successional studies is the …

domestic pig

why do we use domestic pigs is succession studies

readily available, similar in size and tissue levels to human, can easily be modified to replicate a victim’s death scenario, and successional patterns are similar to those found in humans

stage 1 of decomposition (Fresh Stage)

initial decay, 24-72 hrs after death, generally involves mostly microorganisms already present in the body, first wave of insect activity occurs

first wave of insect activity

blow flies, flesh flies, and some house flies oviposit or larviposit on corpse

early arriving flies deposit egg or larvae in … areas of the corpse such as…

moist, orifices and fresh wounds

in later stages of decomposition, moist tissues have been removed or altered, resulting in the corpse no longer being attractive to …

early arriving species

Ants can … oviposition or development of maggots on the corpse

delay

Stage 2 of Decay (Bloat/putrefaction)

3-10 days after death, putrefaction occurs, abdominal cavity opens due to bloat, second wave of insect activity occurs

second wave of insect activity

flesh flies, additional house and blow flies start to arrive as do their predators (Staphylinidae, Silphidae, and Histeridae beetles) and Hymenoptera parasitoids

second wave insects will continue to develop on the corpse until far into … decay

active decay

What also changes during Stage 2: Bloat

soil and normal soil fauna composition beneath the corpse

During stage 2, the soil beneath the corpse tends to become …. form ammonia secretions from the maggot mass

alkaline

Stage 2 can drive changes in the normal soil fauna composition for …. to …. following death

months to years

Stage 3: active decay

10-20 days after death, most body mass is lost, insect activity is the strongest with large maggot masses forming, third wave arrives

Towrards the end of Stage 3: active decay, blowfly larvae…

leave the corpse and pupate in the ground

The number of predacious beetles is very … during stage 3

high

third wave of insect activity

Coffin flies (Phoridae) and fruit flies (Drosophilidae) arrive, attracted by leaking fluids from the corpse

Stage 4: Advanced Decay

20-50 days after deat, butyric fermentation, fat in corpse turns rancid, internal organs liquify, body begins to dry out, fourth wave occurs

fourth wave of insect activity

Cheese skippers (Piophilidae) arrive attracted by the cheese-like scent of butyric acid

Dermestidae (hide beetles) sometimes also arrive, attracted to the dried out tissue

Stage 5: Dry Decay

6 months -10 years after death, slow process, carrion dries out, lasts until corpse is fully skeletonized, fifth wave arrives

fifth wave of insect activity

hide beetles (Dermestidae), checkered beetles (Cleridae), and clothes moths (Tineidae) arrive

in stage 5, hide beetles and checkered beetles feed on remaining …

skin, hair, cartilage, and nails

in stage 5, clothes moth larvae feed on remaining

hair

PMI min estimation at this stage will have substantial error margins

Stage 5: Dry Decay

successional studies can provide diverse information about local carrion species including:

list of species found in a geographical area

seasonal variation in succession

inter- and intra- species dynamics

effects of rainfall and temperature on a corpse as these factor affect insect development

many insects can be quickly identified to family level in the field but identification to … or … may require a specialist

genus or species

identification usually requires rearing fly … to adulthood because species level identification generally requires …

larvae, genitalia

PMI min is obtained by comparing the stage of development of … collected from a corpse with those of the same species under similar …..

maggots, environmental conditions

Fly larval development as PMI min indicator is most relevant between the time the….

first batch of eggs is laid and the flies from those eggs pupate and leave the corpse, first 72 hours

After the first …. hours, there is greater uncertainty about the timing of initial colonization

72 hours

After the first batch of eggs/larvae pupate and leave the corpse, the focus for estimating PMI min shift from larval development to…

insect succession pattern

PMI min can be estimated from successional patterns by using a timeline of insect …. and …. from the corpse

arrival and departure

PMI min can be estimated from successional patterns using the …. present rather than a single species

assemblage of species

insect data of the taxa present are placed into an ….. which records the presence of a taxon at a specific point in the timeline

occurence matrix

barriers to colonization and examples that impact colonization

ecozone, season, sun or shade exposure, habitat/scenario (buildings, vehicles, enclosed spaces), wrapping remains, and burial

the length of the … interval will be impacted by many factors and can rarely be predicted

precolonization interval

precolonization interval

the interval of time before flies find the corpse and stage 1 of decomposition starts

depending on how accessible the corpse is to insects, this interval can last anywhere from hours to weeks

ecozone

the habitat, vegetation, soil type, and meterological conditions of an area

has a major impact on the types and species of insects present as well as their seasonal availability

Data generated in one ecozone can be used to estimate PMI in a different region

True or False

False

in temperate regions, most insect activity is restricted to these seasons

spring, summer, and fall

in tropical and sub-tropical regions, insect activity will occur

year round

relative abundance of certain insects and differing colonization times in different seasons many indication the

season of death

bodies placed in direct sunlight will decompose at a … rate

faster

bodies placed in shade will decompose at a … rate

slower

bodies placed in direct sunlight lose … more rapidly than bodies in the shade

bodies in direct sunlight may … rather than decompose in regions with high temps

mummify

what fly taxa readily enter buildings

blowflies and houseflies

what fly taxa are exclusively found outdoors

flesh flies

outside, decomposition will proceed more …

rapidly

indoors, flies take … to reach the remains due to limited access to the structure so colonization and decomposition may be …

longer, delayed

a greater variety of … larvae have been found to be associated with indoor deaths

fly

a greater variety of … larvae are associated with outdoor deaths

beetle

two major issues with bodies found inside vehicles

likely be a delay before insects enter the vehicle

temperatures are greatly increased in the vehicle

in a vehicle, many usual species involved in decomposition may be excluded if they … rather than fly

crawl

temperatures are greatly increased in vehicles which will … insect development and the rate of decomposition

speed up

major impact of high vehicle temp on PMI estimation

may compensate or overcompensate for the original delay in insect colonization

enclosed spaces may include

garbage cans, suitcases, boxes, refrigerators, dishwashers, safes, etc

enclosed spaces can limit … to the body, preventing or delaying ….

insect access, colonization

insects can use …. to gain entrance to an enclosed space, but such cues do not exist to allow them to..

olfactory cues, leave

large number of …. will be found inside enclosed spaces with a carrion, and can be misleading to investigators

dead adult flies

wrapping is not an impediment to colonization unless the wrapping is very …,

tightly sealed

with wrapping, much of the entomological evidence is actually …

kept and protected

buried remains are not colonized by insects

True or False

False

the time required for insects to reach buried remains is usually…

longer

for buried remains, the sequence of colonization may not start with blowflies

True or False

True

for buried remains, rate of decomposition is usually … due to …. species reaching the body and a … soil temp

slower, fewer, lower

three types of aquatic habitats

freshwater, estuaries, marine

lotic freshwater

moving water systems such as streams/rivers

lentic freshwater

standing water systems such as lakes or ponds

estuaries

transitions between freshwater and marine

marine

include shoreline and open ocean

submersion in … environments can alter the terrestrial faunal succession on carrion as well as the process of decomposition

aquatic

physcial/chemical parameters influence decomposition largely through their effect on … and … interactions

microbial and macroinvertebrate

physcial/chemical parameters that influence organismal colonization of a corpse in aquatic environments

temperature, oxygen content, pH and salinity, the corpse itself (clothing, trauma, etc.)

temperature is the foremost environmental factor influencing the rate of corpse decompostion via the timing of …, the rate of …, and …. of aquatic organisms

oviposition/colonization

larval growth

survivorship

…. water temperatures slow down the process of decomposition, especially microbial breakdown

cold-water

… water temperatures accelerate decomposition

warm-water

higher temperature water increases …. by altering the quantity and quality of organic matter associated with the corpse

larval growth

the thermal diversity to which aquatic organisms are exposed to varies by … and … in the same body of water

location and timing

water temp has a significant impact of number of degree days, often ….the number of degree days needed for larval development

increasing

while annual temperature range is less in … environments, the seasonal temperature change is greater than that in … environments

lotic;

lentic

lotic environments include

moving water such as streams/rivers

lentic environments include

standing water such as ponds and lakes

daily temperature changes are often greater in … than in non-shore areas of lakes

streams

thermal stratification is rare in … environments but common in …

lotic

lakes

thermal stratification

different temperatures between top, middle, and bottom layers of a body of water

dissolved oxygen and temperature are …. correlated

negatively

the higher the temperature, the … the oxygen content

lower

small, fast flowing streams usually have … oxygen levels

high

stream pools, ponds, some lakes, and deep oceans have relatively … oxygen levels

low

in … environments, conditions within a few meters of the surface are often anoxic

lentic /standing water

in … environments, water can reach the max level of oxygen saturation

lotic/ flowing water

many insects show a preference for … waters

cold

in low oxygen environments there is … species diversity

low

low oxygen environments lead to … rate of decomposition

slower

insects in warmer and more stagnant (lentic) waters must have specific … and … adaptations to survive in low oxygen conditions

respiratory and behavioral

extreme pH levels (acidic or basic) will lead to … rates of decomposition

slower