Megaselia scalaris (Loew) (Diptera: Phoridae) is a cosmopolitan scuttle fly of medical and forensic importance. This
species is generally small, humpbacked and is a prominent decomposer of corpses indoors. Taxonomically, adult sexes
can be distinguished based on the characteristics of the terminal segments of the abdomen. In this report, the terminalia
of adult male and female M. scalaris were examined using scanning electron microscope (SEM). The terminal segment
of an adult female is less complex compared to male, consisting of an ovipositor and cerci. In male, the hypopygium
consists of epandrium, hypandrium, anal tube and penis complex. A pair of long and feathered setae was attached to the
tip of the anal tube and tapered. The application of SEM to identify this species isuseful and can be expanded to other
species in this fly group.
Phorid flies play an important role in forensic cases and can cause myiasis in humans. Studies on phorid flies species diversity are still limited in Malaysia. This research was carried out to collect information about species and frequency distribution of phorid flies as to provide more information on their roles in forensic and medical entomology. Bait trap was used with 100 g beef liver as baits. The species of the flies were identified using identification keys from Disney as well as Brown and Oliver. There were 449 phorid flies found in Kepong, Kuala Lumpur including Megaselia scalaris, Megaselia spiracularis, Megaselia sp. and phorid flies of genus X. Female phorid flies (98.89%) were found more prone to be trapped compared to male phorid flies (1.11%). Most phorid flies trapped in Kepong, Kuala Lumpur were from genus Megaselia and consisted of female flies. A total of five species of phorid flies probably new to science were also discovered. This study showed that Megaselia flies were found indoors rather than in open spaces. This was corresponding to their discoveries among the decomposing corpse found inside premises.
Development of insects in laboratory for minimum post mortem interval estimation (mPMI) or time of colonisation (TOC) in
forensic entomology can be affected by the type and quality of food consumed during larval period. Since mPMI estimation
also involves analysis of larval specimens collected from burned human remains, it is important to study if burned tissues
could affect growth of sarcosaprophagous larvae. This study investigated the effect of burned tissues on the size and
developmental period of Megaselia scalaris (Loew) (Diptera: Phoridae), a species of forensic importance. Development
of M. scalaris on 75 g burned cow’s liver was compared with control liver in three study replicates. Mean larval length
(2.87 ± 0.11 mm) and weight (0.81 ± 0.08 mg) of M. scalaris larvae in burned liver diets were significantly lower than
larval length (5.03 ± 0.15 mm) and weight (2.85 ± 0.21 mg) of control liver diets (p < 0.001) whilst mean pupal length
(2.53 ± 0.06 mm) and weight (0.92 ± 0.06 mg) in burned liver diets were significantly lower than pupal length (3.52 ±
0.06 mm) and weight (2.84 ± 0.16 mg) in control liver diets (p < 0.001). Development of larvae in burned liver was 5-9
hours slower than those feeding on control liver based on single observation. Although the assessment is preliminary, the
findings indicate physical growth of larvae feeding on burned animal tissues was affected and entomological specimens
recovered from burned remains should be evaluated carefully to avoid errors in mPMI/TOC estimation. Limitations and
suggestions for further research are also presented herein.
In forensic entomology practice, it is more common to use raw animal tissue to breed dipteran larvae and it often brings unpleasant odour in the laboratory. Few studies suggested the use of synthetic diets, mainly agar-based media, as alternatives to animal tissue but it is rarely being practiced in forensic entomology laboratory. The present study observed the growth of a forensically important fly, Megaselia scalaris (Loew) on raw cow’s liver, nutrient agar, casein agar and cow’s liver agar. A total of 100 M. scalaris eggs were transferred each into the different media and placed in an incubator at 30°C in a continuous dark condition. Data on length and developmental period were collected by randomly sampling three of the largest larvae from each rearing media, twice a day at 0900 and 1500 hours until pupariation. M. scalaris larvae reared on raw cow’s liver recorded the highest mean length (4.23 ± 1.96 mm) followed by cow’s liver agar (3.79 ± 1.62 mm), casein agar (3.14 ± 1.16 mm) and nutrient agar (3.09 ± 1.11 mm). Larval length in raw liver and liver agar were significantly different from those in nutrient and casein agar (p < 0.05). Larvae bred in liver agar and raw liver recorded the shortest larval duration before entering the post-feeding stage (89 hours), followed by nutrient agar (119 hours) and casein agar (184 hours). Total developmental time from oviposition until adult emergence for M. scalaris in liver agar and raw liver was approximately 163 hours. All puparia in nutrient agar and casein agar failed to hatch. This research highlighted the potential use of cow’s liver agar as an alternative diet of raw liver to culture M. scalaris in laboratory.
Ahmad Firdaus Mohd Salleh, Anita Talib, Mohamed Abdullah Marwi, Noor Hayati Mohd Isa, Syamsa Rizal Abdullah, Raja Muhammad Zuha Raja Kamal Bashah, et al.
Chrysomya megacephala (Fabricius) dan Chrysomya rufifacies (Macquart) adalah merupakan dua spesies lalat penting yang boleh dijadikan sebagai penunjuk terbaik untuk menganggarkan selang masa kematian atau Post Mortem Interval (PMI) untuk kegunaan dalam sains forensik. Penentuan PMI adalah berdasarkan kepada saiz dan peringkat perkembangan larva. Kajian perkembangan telur, larva dan pupa lalat Ch. megacepahala dan Ch. rufifacies dijalankan di bawah suhu 27ºC, 30ºC dan 33ºC di makmal dengan menggunakan kebuk pertumbuhann serangga. Data daripada kajian digunakan untuk menghasilkan satu graf pertumbuhan dan Jam Darjah Terkumpul (ADH) bagi kedua-dua spesies. Ch. megacephala mengambil masa selama 9.15 hari pada suhu 27ºC, 8.54 hari (30ºC) dan 6.76 hari (33ºC) untuk melengkapkan satu kitar hidup. Pada C. rufifacies pula, kitar hidupnya lebih lama berbanding Ch. megacephala iaitu 9.92 hari pada suhu 27ºC, 9.13 hari (30ºC) dan 7.44 hari (33ºC). Telur bagi kedua-dua spesies menetas lebih cepat pada suhu 33ºC berbanding dua suhu yang lainnya. Nilai ADH yang rendah pada sesuatu suhu, menunjukkan sesuatu spesies lebih cepat melengkapkan suatu kitar hidup. Penemuan ini berguna dalam menganggarkan selang masa kematian bagi mayat yang dijumpai pada suhu persekitaran yang berlainan.
This study was conducted to examine the effect of malathion on the development of Chrysomya megacephala. A total of 12 adult Sprague-Dawley rats was divided into 4 groups. Each animal in the 4 groups was given orally 0 (control), 10, 25 and 50ml/kg body weight of malathion, respectively. Chrysomya megacephala larvae were then allowed to grow on the liver of carcass. Larvae development was estimated by means of weight and length, time of adult emergence and survival rate. Results indicated that for the first 6 to 30 hours, larvae from control group developed more rapidly than larvae feeding on tissue containing malathion. However, the 3 doses of malathion did not exhibit significant impact on larvae length and weight. The time required for adult emergence was significantly greater for malathion-treated colony which was 10 days compared to 7 days in control colony. Control larvae of C. megacephala had higher survival rate compared to larvae exposed to the three different doses of malathion. Analysis of the tissues indicated that all rats and fly samples were positive for malathion. Malathion concentration was highest in liver. It was concluded that the presence of malathion altered the development rate of C. megacephala and thus disrupted normal postmortem interval estimation.