Questions Set-1_Forensic Entomology_Forensic Science

Questions Set-1_Forensic Entomology_Forensic Science

1. In forensic entomology, which factor MOST critically limits the accuracy of post-mortem interval (PMI) estimation based on insect development?

a) Species misidentification of larvae
b) Geographic variation in insect fauna
c) Temperature fluctuation during larval development
d) Presence of multiple insect species on the corpse

Answer: c) Temperature fluctuation during larval development

Explanation:
Insect growth and development are temperature-dependent and follow accumulated degree hours/days (ADH/ADD). Even minor fluctuations in ambient or maggot-mass temperature can significantly alter larval growth rates, leading to major errors in PMI estimation. While species identification and faunal variation are important, temperature remains the most critical limiting factor in developmental-based PMI calculations.

 

2. Which developmental stage of blowflies (Calliphoridae) is considered most reliable for precise PMI estimation in early post-mortem periods?

a) Egg stage
b) First instar larva
c) Third instar larva
d) Pupal stage

Answer: c) Third instar larva

Explanation:
The third instar larva is the largest, most active feeding stage with well-defined morphological features. It allows accurate measurement of length, weight, and spiracular development, which are crucial for age estimation. Eggs and early instars develop rapidly and are more susceptible to environmental variability, while pupae provide broader PMI ranges.

 

3. Which of the following insect species is most indicative of a body having been moved indoors after death?

a) Chrysomya megacephala
b) Calliphora vicina
c) Musca domestica
d) Lucilia sericata

Answer: b) Calliphora vicina

Explanation:
Calliphora vicina prefers cooler temperatures and indoor environments and is often associated with bodies found inside buildings. Its presence on a corpse discovered outdoors may suggest post-mortem relocation, making it a crucial species in forensic reconstruction.

 

4. The phenomenon of maggot mass effect primarily influences PMI estimation by:

a) Altering larval species composition
b) Increasing oxygen consumption in larvae
c) Elevating local temperature around larvae
d) Delaying pupation

Answer: c) Elevating local temperature around larvae

Explanation:
Maggot masses generate significant metabolic heat, often raising local temperatures by 10–20 °C above ambient conditions. This accelerates larval development and, if not accounted for, can lead to underestimation of PMI. Accurate forensic entomological analysis must correct for this effect.

 

5. Which chemical analytical approach is increasingly used in forensic entomology to detect ante-mortem drug or poison intake using insects?

a) Spectrophotometry of larval extracts
b) Histological examination of larvae
c) Entomotoxicological analysis by GC-MS
d) Enzyme-linked immunoassay of pupal casings

Answer: c) Entomotoxicological analysis by GC-MS

Explanation:
Entomotoxicology involves analyzing insect tissues (larvae, pupae) for drugs or toxins when human tissues are unavailable or degraded. GC-MS provides high sensitivity and specificity for detecting narcotics, pesticides, and heavy metals, making it the gold standard in advanced forensic entomological investigations.

 

6. Which entomological parameter is MOST reliable for PMI estimation when a body is discovered after several weeks?

a) Egg hatch time
b) Larval length
c) Insect succession pattern
d) Maggot mass temperature

Answer: c) Insect succession pattern

Explanation:
After prolonged post-mortem periods, larval development becomes less useful due to pupation or emergence. Succession patterns, involving predictable arrival of insect taxa over time, provide a broader PMI window and are essential in advanced decomposition stages.

 

7. Which order of insects typically colonizes a corpse during the dry remains stage of decomposition?

a) Diptera
b) Hymenoptera
c) Coleoptera
d) Lepidoptera

Answer: c) Coleoptera

Explanation:
Beetles (Coleoptera), particularly Dermestidae, colonize remains during late decomposition, feeding on dried tissues, hair, and ligaments, making them crucial indicators of extended PMI.

 

8. Which anatomical feature is MOST useful for differentiating between second and third instar fly larvae?

a) Body segmentation
b) Mouth hooks
c) Posterior spiracles
d) Cephalopharyngeal skeleton size

Answer: c) Posterior spiracles

Explanation:
Posterior spiracle morphology changes distinctly with each instar. The number, shape, and orientation of spiracular slits provide the most reliable criterion for larval instar determination.

 

9. Which environmental condition significantly delays insect colonization of a corpse?

a) High humidity
b) Presence of open wounds
c) Burial at shallow depth
d) Low ambient temperature

Answer: d) Low ambient temperature

Explanation:
Insect activity and oviposition are temperature-dependent. Low temperatures delay insect arrival and larval development, causing overestimation of PMI if not corrected.

 

10. What is the PRIMARY forensic significance of puparial cases found at a crime scene?

a) Indicate time of egg laying
b) Provide DNA of the victim
c) Indicate completion of larval development
d) Identify insect species directly

Correct Answer: c) Indicate completion of larval development

Explanation:
Puparial cases indicate that larvae have completed feeding and entered pupation, allowing investigators to calculate minimum PMI based on total developmental time.