Zuha Raja Muhammad, Omar Baharudin
Forensic Science Program, School of Diagnostic and Applied Health Sciences, Faculty of Health Sciences, Universiti Kebangsaan Malaysia (National University of Malaysia), Jalan Raja Muda Abdul Aziz, 50300, Kuala Lumpur, Malaysia,
Parasitol Res. 2014 Jun;113(6):2285-94. doi: 10.1007/s00436-014-3883-z. Epub 2014 Apr 12.
Cosmopolitan scuttle fly, Megaselia scalaris (Loew) (Diptera: Phoridae) is one of the commonest forensic species recorded colonizing human corpse indoors and in concealed environment. The occurrence of this species in such environments provides a higher evidential value to assist estimation of postmortem interval (PMI) compared to other forensically important dipterans. However, developmental and size data of M. scalaris are still lacking and they are derived from a limited range of thermal values. The objective of this study is to develop the growth model of M. scalaris by emphasizing the size range of larvae and puparia at different constant temperatures. This species was reared in six replicates at eight varying constant temperatures ranging from 23 to 36 °C and cow's liver was provided as food source. Larvae and puparia were sampled at set time intervals and measured by their length and weight. Because interpretation of forensic entomological evidence is subject to application of different techniques, development of M. scalaris is expressed herein by using developmental table, length/morphological stage diagrams and linear/nonlinear estimation methods. From the findings, it is very important to highlight that sexual dimorphism of M. scalaris during post feeding larva and pupa stage could be observed based on size and developmental periods. Mean length and weight ratios of male to female puparia are approximately 0.8 and 0.3-0.5, respectively, indicating sexual dimorphism of this species. Developmental period in female are 4.0-11.4 h (post feeding larval stage), 3.7-24.0 h (pupal stage), and 3.0-20.1 h (total developmental period) longer in male. Due to this dimorphism, PMI estimation using M. scalaris post feeding larva or puparium specimens must be carried out carefully by to avoid inaccuracy and misinterpretation.
世界性的蚤蝇，即黑腹蚤蝇（Megaselia scalaris (Loew)）（双翅目：蚤蝇科）是在室内和隐蔽环境中定殖于人类尸体的最常见法医昆虫物种之一。与其他具有法医重要性的双翅目昆虫相比，该物种在这类环境中的出现对于协助推断死后间隔时间（PMI）具有更高的证据价值。然而，黑腹蚤蝇的发育和大小数据仍然缺乏，且这些数据来自有限的温度范围。本研究的目的是通过强调不同恒温下幼虫和蛹的大小范围来建立黑腹蚤蝇的生长模型。该物种在23至36°C的八个不同恒温下以六个重复进行饲养，并提供牛肝作为食物来源。在设定的时间间隔对幼虫和蛹进行采样，并测量其长度和重量。由于法医昆虫学证据的解释取决于不同技术的应用，本文通过使用发育表、长度/形态阶段图以及线性/非线性估计方法来表示黑腹蚤蝇的发育情况。从研究结果来看，非常重要的一点是要强调，在取食后幼虫和蛹阶段，可以根据大小和发育时期观察到黑腹蚤蝇的两性异形。雄性和雌性蛹的平均长度比和重量比分别约为0.8和0.3 - 0.5，表明该物种存在两性异形。雌性在取食后幼虫阶段的发育时间比雄性长4.0 - 11.4小时，蛹期长3.7 - 24.0小时，总发育时长3.0 - 20.1小时。由于这种两性异形，使用黑腹蚤蝇取食后幼虫或蛹标本进行PMI估计时必须谨慎操作，以避免不准确和错误解读。
