Third-Instar Larvae of Forensically Important Insects as a Tool for Estimating the Minimum Post-Mortem Interval in Dog Carcasses Under High Summer Temperatures in Southern Iraq

Forensic entomology applies knowledge of insect biology to medico-legal investigations, most critically for estimating the minimum post-mortem interval (PMImin) when conventional pathological methods become unreliable. This study evaluated third-instar larval development and the accumulated degree hours (ADH) method for estimating PMImin in dog (Canis lupus familiaris) carcasses under the extreme summer temperatures of Al-Diwaniyah, Southern Iraq (43 °C). Twelve carcasses were studied across two contrasting habitats — an agricultural area and a cemetery — with three carcasses placed on the ground surface and three buried at 50 cm depth in each habitat. Four forensically important species were recorded across all groups: Calliphora vicina, Calliphora vomitoria, Chrysomya megacephala, and Chrysomya albiceps. PMImin estimates for surface carcasses ranged from 8.143 h (C. vicina, cemetery) to 11.000 h (C. vomitoria, cemetery surface). For buried carcasses, estimates ranged from 12.727 h (C. vicina and C. megacephala, cemetery buried) to 20.727 h (C. megacephala, agricultural buried). Burial at 50 cm consistently and substantially increased PMImin relative to surface carcasses. Cemetery surface carcasses yielded marginally higher estimates than agricultural ones for shared species, reflecting habitat-level microclimatic differences. Calliphora vicina consistently produced the earliest estimates, confirming its value as the closest entomological indicator of the time of death. The findings demonstrate that third-instar larvae are reliable biological clocks for PMImin estimation in hot-climate Iraq and that both burial depth and habitat type materially affect entomological estimates.