A body is discovered outdoors in summer with maggot masses present. Third-instar larvae of Calliphora vicina (blowfly) are identified, and the accumulated degree-days (ADD) to reach this stage from egg is 120. The average temperature since death was 20°C, with a base temperature of 10°C for this species. What is the estimated minimum postmortem interval?
- A 6 days
- B 3 days
- C 12 days ✓
- D 20 days
Correct answer: C. 12 days
Explanation
Accumulated degree-days (ADD) = (average temperature − base temperature) × number of days. Here, ADD = (20 − 10) × days = 10 × days. If ADD to reach third instar = 120, then days = 120 ÷ 10 = 12 days. This is the minimum PMI because flies colonize the body within hours of death, so the larval age represents the minimum time since death. ADD-based calculations are the standard entomological method for PMI estimation, with species-specific base temperatures and developmental data.
Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.