Insect larvae recovered from decomposing pig carrions in Okija, Anambra State, Nigeria

Abstract

Insect immature stages found on decomposing cadavers are source of information that assist forensic investigators elucidate the time of questionable death. Hence, insect larvae recovered from decomposing pig carrions as models to human cadavers in Okija (05 °53.240"′N and 006 °46.510″E) Anambra State, Nigeria were reared to adults in the laboratory by adopting a simple method to assist amateurs. Samples of the larvae were collected with camel hair (student’s art) brush, 5ml spoon and blunt forceps. They were collected in batches and placed in rearing containers (9.0 cm depth and 6.5 cm width) and labeled accordingly. Each sampled batch was replicated thrice and reared under ambient temperature (28.6 ± 0.15 ºC) and relative humidity (68.5 ± 1.34 %). The reared insect larvae later emerged and they were taxonomically identified. The species were ascertained by a taxonomist at Insect Museum, Institute of Agricultural Research, Ahmadu Bello University, Zaria. The species include: Chrysomya albiceps, Chrysomya chloropyga, Chrysomya regalis, Isomyia dubiosa, Isomyia sp. (Calliphoridae), Sarcophaga inzi (Sarcophagidae), Chrysomyza africana (Ulidiidae), Musca domestica (Muscidae), Hermetia illucens (Stratiomyiidae), Dermestes frischii (Dermestidae) and Necrobia rufipes (Cleridae). The Calliphoridae first developed into adults at day 8, Sarcophagidae day 16, Ulidiidae, day 22, Muscidae, day 31, Stratiomyiidae, day 33, Dermestidae, day 38 and Cleridae, day 53. The probable reasons for the insect larvae to associate with the carrions were highlighted and their forensic importance discussed.

Keywords: Insect larvae, Carrions, Decomposition stages, Forensic science