Biology and Morphology of Forensic Entomological Important Sarcophagid Flies (Diptera: Sarcophagidae)

Abstract

The fly species, Sarcophagid (Diptera: Sarcophagidae), is forensically important, due its larvae being associated with human corpses. Therefore, these larvae can be used as entomological evidence in forensic investigations. In Thailand, Sarcophaga (Boettcherisca) nathani and Sarcophaga (Lioproctia) pattoni are found commonly both in urban and forested areas. This study aimed to investigate the biology and morphology of B. nathani and L. pattoni at all stages in their life cycle. The morphological characteristics of the egg, larva, pupa and adult were observed under light microscope (LM) and scanning electron microscope (SEM). The eggs of B. nathani measured 1.92±0.13 mm in length and 0.56±0.04 mm in width (n=75), while those of L. pattoni were 2.29±0.12 mm in length and 0.63±0.06 mm in width (n=86). LM and SEM observations of the larvae showed distinct characteristics of the cephalopharyngeal skeleton, number and arragement of papillae in the anterior spiracle, intersegmental spines between the prothorax and mesothorax, and posterior spiracle. SEM micrographs of puparia displayed unique characteristics between the species, such as the number and arragement of papillae in the anterior spiracle, intersegmental spines between the prothorax and mesothorax, and spiracular tufts on the posterior spiracle.

The genitalia in adult male B. nathani and L. pattoni displayed distict features of the sternite 5, phallus, basiphallus, cercus, epandrium juxta, postgonite, pregonite and vesica; whereas the adult female of these species showed nine stages of ovariole development. Comparision between the mixed and isolated females of both these species revealed that the ovariole of isolated females developed slower than that of mixed ones. Investigation of the biology was performed to determine the larval developmental rate by measuring three sample larvae every 12 hr by observed three replicates. The results indicated that total development from first instar to adults of B. nathani and L. pattoni took a period of 15 and 21 days, respectively. The developmental rate of the length and width of both fly species also were obtained. Results from this study provided information of the biology and morphology of both flesh fly species, which may be useful in species identification and estimation of post-mortem interval in forensic investigation.