PDF(Pubmed)
Abstract：
Accurate minimum post-mortem interval (minPMI) estimations often rely on a precise age determination of insect developmental stages, which is significantly influenced by environmental temperature. An optimal preservation of the entomological samples collected at crime scenes is pivotal for a reliable aging of immature insect samples. For blow flies (Diptera: Calliphoridae), the most widely used insect indicators in forensic investigations, an appropriate preservation of tissues is particularly important in the case of puparial samples because aging methods for intra-puparial forms usually depend on morphological analyses; however, although informative soft tissues and structures could be discoloured and/or distorted if they are not properly fixed, there is a lack of studies to assess different methods for the optimal preservation of intra-puparial forms collected in forensic investigations. The present study compares three preservation methods for intra-puparial forms of the blow fly Calliphora vicina Robineau-Desvoidy, 1830: (i) direct immersion into 80% ethanol, (ii) puncturing of the puparium and hot water killing (HWK) prior to preservation in 80% ethanol, and (iii) HWK without puncturing before preservation in 80% ethanol. External and internal morphological analyses of intra-puparial forms of different ages were conducted to assess the quality of preservation. The results indicate that direct immersion in ethanol led to poor preservation, affecting both external and internal tissues. Both methods with HWK resulted in a better preservation, but puncturing resulted, in some cases, in physical damage of the specimens. HWK without puncturing emerged as the optimal preservation method, consistently yielding high preservation scores for both external and internal morphological analyses. These findings have practical implications for forensic practitioners and emphasise the need for updating some published guidelines and protocols in forensic entomology.
摘要：
准确的最小验尸间隔（minPMI）估计通常依赖于昆虫发育阶段的精确年龄确定，受环境温度的影响很大。在犯罪现场收集的昆虫学样品的最佳保存对于未成熟昆虫样品的可靠老化至关重要。对于苍蝇（双翅目：Calliphoridae），法医调查中使用最广泛的昆虫指标，在阴部样本的情况下，组织的适当保存尤为重要，因为阴部内部形式的老化方法通常取决于形态学分析;然而，尽管如果没有正确固定，信息丰富的软组织和结构可能会变色和/或变形，缺乏研究来评估法医调查中收集的阴部内部形式的最佳保存的不同方法。本研究比较了三种保存方法，以保存pay蝇CalliphoravicinaRobineau-Desvoidy的阴部形式，1830：（i）直接浸入80％乙醇中，(ii)在保存在80%乙醇中之前,刺破脓毒和热水杀灭(HWK),和(iii)在80%乙醇中保存之前未刺穿的HWK。对不同年龄的阴部形式进行了外部和内部形态分析，以评估保存质量。结果表明，直接浸入乙醇会导致保存不良，影响外部和内部组织。HWK的两种方法都能更好地保存，但是穿刺结果，在某些情况下,在标本的物理损伤中。不穿刺的HWK成为最佳保存方法，对于外部和内部形态分析，始终产生较高的保存分数。这些发现对法医从业人员具有实际意义，并强调需要更新一些已发布的法医昆虫学指南和协议。
