Somsak Piangjai

Forensic entomology cases in Thailand: a review of cases from 2000 to 2006

This paper presents and discusses 30 cases of cadavers that had been transferred for forensic entomology investigations to the Department of Forensic Medicine, Faculty of Medicine, Chiang Mai University, northern Thailand, from 2000 to 2006. Variable death scenes were determined, including forested area and suburban and urban outdoor and indoor environments. The fly specimens found in the corpses obtained were the most commonly of the blow fly of family Calliphoridae, and consisted of Chrysomya megacephala (F.), Chrysomya rufifacies (Macquart) Chrysomya villeneuvi Patton, Chrysomya nigripes Aubertin, Chrysomya bezziana Villeneuve, Chrysomya chani Kurahashi, Lucilia cuprina (Wiedemann), Hemipyrellia ligurriens (Wiedemann), and two unknown species. Flies of the family Muscidae [Hydrotaea spinigera Stein, Synthesiomyia nudiseta (Wulp)], Piophilidae [Piophila casei (L.)], Phoridae [Megaselia scalaris (Loew)], Sarcophagidae [Parasarcophaga ruficornis (F.) and three unknown species], and Stratiomyiidae (Sargus sp.) were also collected from these human remains. Larvae and adults of the beetle, Dermestes maculatus DeGeer (Coleoptera: Dermestidae), were also found in some cases. Chrysomya megacephala and C. rufifacies were the most common species found in the ecologically varied death scene habitats associated with both urban and forested areas, while C. nigripes was commonly discovered in forested places. S. nudiseta was collected only from corpses found in an indoor death scene.

First Report of Human Myiasis Caused by Chrysomya megacephala and Chrysomya rufifacies (Diptera: Calliphoridae) in Thailand, and Its Implication in Forensic Entomology

Abstract We report a forensic entomology case associated with human myiasis in Chiang Mai Province, northern Thailand. The remains of a 53-yr-old-male were concurrently infested with third instars of the two blow fly species, Chrysomya megacephala (F.) and Chrysomya rufifacies (Macquart), near a severe tumor lesion presented on the lower right leg. The presence of third instars, ≈5 d old, on the day following postmortem indicated that myiasis occurred before death. This is the first report of both fly species acting as a myiasis-producing agent in Thailand. Unsynchronized data between the age of fly larvae due to myiasis premortem and verified age/condition of the corpse suggest a potential complication and error in the estimation of postmortem interval if other predisposition fly infestations are not considered.

The First Documented Forensic Entomology Case in Thailand

Abstract The forensic entomology case described herein is the first such case documented in Thailand. A mummified corpse of a 32-yr-old man was discovered in a forested habitat, with the larvae of six species of flies (Diptera) found in association with the corpse at the time of its discovery, i.e., those of Hydrotaea (=Ophyra) spinigera Stein (family Muscidae), Piophila casei (L.) (family Piophilidae), Megaselia scalaris (Loew) (family Phoridae), Sargus sp. (family Stratiomyidae), and larvae of two unidentified flesh fly species (family Sarcophagidae). The presence and age of the larval specimens of P. casei, M. scalaris, and H. spinigera gave entomological evidence that the postmortem interval for the corpse was 3–6 mo. This report also documents some of the forensically important fly species that occur in Thailand.

Morphology of immature stages of Hemipyrellia ligurriens (Wiedemann) (Diptera: Calliphoridae) for use in forensic entomology applications

In forensic investigations, all immature stages of flies (egg, larvae, and puparium) can serve as entomological evidence at death scenes. These insects are primarily used to estimate the post mortem interval (PMI), but can also be involved in the analysis of toxic substances, determining manner of death, and in indicating relocation of a corpse in homicide cases. In this study, we present the morphology of the egg, larvae, and puparium of Hemipyrellia ligurriens, a blow fly species of forensic importance in Thailand. Examination was conducted using scanning electron microscopy (SEM). The egg stage was found to display a relatively wide plastron region (or median hatch line area) that spans almost the entire length of the egg. The median hatch line is oriented in an upright position. External chorionic sculpture of the egg is present in a hexagonal pattern whose reticular boundaries are slightly elevated. In the larval stages, the most prominent morphological changes were detected upon comparison of the first to the second instar; whereas, the differences between second and third instar larvae were less obvious outside of the increase in number of posterior spiracular slits. Most of the major differences involve body size and structure of the anterior and posterior spiracles. Each anterior spiracle in both the second and third instars projects five to seven papillae apically. Each posterior spiracular disc of a third instar exhibits a complete peritreme, three spiracular slits, and a prominent button that is ventromedially located. The puparium is coarctate and features a clustered bubble membrane comprised of ≈57 mammillate structures positioned dorsolaterally on each side of the first abdominal segment in young puparia. This feature is replaced by short, tubular respiratory horns in aged puparia. This study provides more detailed exposure of important morphological features that can be used for accurate identification of immature stages of H. ligurriens. Information presented can aid in forensic investigations involving this fly species.

Differentiation of the Third Instar of Forensically Important Fly Species in Thailand

Abstract Differentiation of the third instar of forensically important fly species in Thailand was performed using light microscopy, based on their morphological criteria for fly identification. Four species of the family Calliphoridae [Chrysomya rufifacies (Macquart), Chrysomya megacephala (F.), Chrysomya nigripes Aubertin, and Lucilia cuprina (Wiedemann)] and two species of the family Muscidae [Musca domestica L. and Hydrotaea (=Ophyra) spinigera Stein] were examined in this study, with the features of the anterior spiracles, dorsal spines between the prothorax and mesothorax, and posterior spiracles being emphasized. The comparisons, presented herein, should be helpful for forensic practitioners to readily distinguish the third instars of fly species found associated with human cadavers, before their use for further forensic investigations.

Morphology of the puparia of the housefly, Musca domestica (Diptera: Muscidae) and blowfly, Chrysomya megacephala (Diptera: Calliphoridae)

Examination of the puparia of the housefly, Musca domestica L. and blowfly Chrysomya megacephala (F.), through scanning electron microscopy (SEM), revealed many differences in the profile of their morphology. Special attention was focused on puparial characteristics used to differentiate between the two fly species studied, and between other forensically important flies. Results of this study indicate that the housefly puparia are almost evenly rounded at both ends and the anterior spiracle bears six papillae. A pair of pupal respiratory horns is found laterally before the posterior boundary of the first abdominal segment, bearing numerous papillae that have a longitudinal opening along the oval convex base. The peritreme of each posterior spiracle forms a crude forward or reverse D-shape, encircling three sinuous slits. The blowfly pupariums anterior spiracle contains 8–12 papillae. The pupal respiratory horns protrude slightly and in some specimens a group of ~38 globules on the bubble-like membrane may be observed. Each of the posterior spiracles is more or less an oval- shaped peritreme, encircling three straight spiracular slits. The anatomical features presented herein allow for the differentiation of puparia of the two fly species studied and could prove useful in future forensic entomological assessments.

Evidence of Haplorchis taichui infection as pathogenic parasite: three case reports.

Haplorchis taichui is the minute intestinal fluke which parasitizes the small intestine of humans and other mammals. We present the pathology in the small intestine of 3 human cases caused by H. taichui. Microscopic examination revealed mucosal ulceration, mucosal and submucosal haemorrhages, fusion and shortening villi, chronic inflammation, and fibrosis of the submucosa. This finding clearly indicated H. taichui as pathogenic; thus prevention of infection and treatment should be paramount.

Ultrastructure of eggshell of Chrysomya nigripes Aubertin (Diptera: Calliphoridae)

We examined the eggshell structure of the blowfly, Chrysomya nigripes Aubertin, a species of forensic importance, using scanning electron microscopy. A relatively wide plastron region was located dorsally. It extended almost the entire length of the egg and bifurcated slightly, close to the micropyle, which is a deep cavity surrounded by an elevated, fine, wavy rim. The chorionic sculpture had an hexagonal pattern, with a smooth and elevated boundary. The ruptured eggshell showed the outermost exochorion, membranous outer endochorion and pillar layer, which also had an hexagonal pattern on a perforated mesh pillar layer. This study provides a greater database on the egg of this forensically significant blowfly.

Larval Morphology of Chrysomya nigripes (Diptera: Calliphoridae), a Fly Species of Forensic Importance

Abstract The morphology of all instars of Chrysomya nigripes Aubertin, a blow fly species of forensic importance, is presented with the aid of both light microscopy and scanning electron microscopy (SEM). Morphological features of the cephalopharyngeal skeleton, anterior spiracle, posterior spiracle, and dorsal spines between the prothorax and mesothorax are highlighted. No consistent features were found, even using SEM, for distinguishing the first instar of C. nigripes from that of Chrysomya megacephala (F.) or Chrysomya rufifacies (Macquart), two other commonly associated blow fly species in corpses in Thailand. Several features observed in second and third instars proved to be valuable characteristics for separating these species.

Morphology of puparia of Megaselia scalaris (Diptera: Phoridae), a fly species of medical and forensic importance

Megaselia scalaris (Loew), a scuttle fly, is a fly species of medical and forensic importance. For use in forensic investigation, fly specimens found to associate with human corpses have to be identified at species level. Herein, we present the morphology of the puparia of the above fly species using scanning electron microscopy. The characteristic of the intersegmental spines along the dorsal and lateral segments and sculpture of the pupal respiratory horn of this puparia may be useful in future studies, to distinguish it from other closely related species.