根据食尸性蝇类推断死亡时间的研究进展

法医昆虫学是应用昆虫学知识解决法医实践中所遇到的相关问题的一门科学。食尸性蝇类在尸体的腐败分解中发挥着重要的作用,运用食尸性蝇类的特点可以更准确进行死亡时间推断,为侦查破案提供线索。本文对依据食尸性蝇类推断死亡时间的方法进行综述,以期为后续的研究与实践应用参考和借鉴。     

嗜尸性蝇类种属鉴定研究进展

死亡时间(postmortem interval,PMI)推断一直是困扰法医学工作者的难题之一,尤其是荒郊野外或偏僻屋内的高度腐败尸体更是难以使用常规手段推断PMI,因此常需要借助现场中的昆虫证据来推断。不同种属的蝇类发育时间差异较大,在实际案件中,如果不进行种属鉴定而直接测量蝇蛆体长、计算积温或演替阶段,或是基于错误的种属鉴定来计算,往往会导致推算出的结果与实际PMI之间出现较大偏差,误导案件侦查方向。因此,使用法医昆虫学方法来推断腐败尸体PMI,必须先进行准确的昆虫种属鉴定。本文对嗜尸性蝇类不同虫态的大体和超微形态学种属鉴定以及分子生物学种属鉴定方法进行综述,以期为相关研究和实践提供新思路和新方法,为法医昆虫学在鉴定实践的应用推广提供参考。     

呼和浩特地区夏秋季常见嗜尸性蝇类的研究

目的研究呼和浩特地区常见嗜尸性苍蝇种类及其出现规律。方法观察法研究7～10月份兔尸上嗜尸性苍蝇种类变化。结果该地区兔尸上出现的双翅目嗜尸性苍蝇3科8属10种,主要有蝇科的家蝇、舍蝇、开普黑蝇、刺足齿股蝇、厩腐蝇;丽蝇科的丝光绿蝇、大头金蝇、铜绿蝇;麻蝇科的棕尾别麻蝇、肥须亚麻蝇。上述蝇类在尸体上出现时间及部位表现出很强的规律性。结论研究结果有望成为法医在呼和浩特地区对尸体进行死亡时间推断的依据。     

法医昆虫学在死亡时间推断中应用3例

在自然界,动物一旦发生死亡,昆虫往往是尸体的首先发现者。它们在P体上取食繁衍,成为尸体的主要毁坏者。最先到达尸体的是蝇类,其次是鞘翅目昆虫。另外还有蚂蚁。螨类、膜翅目昆虫。欧洲的一些科学家发现昆虫在尸体上的发育演变很有规律,并将其应用于法医调查,由此形成了现代的新兴科学即法医昆虫学（F。rensicEnt。m。l。gy）‘’．近20年来,法医昆虫学研究在国外发展很快,有关法医昆虫学方面的文章,及应用昆虫学知识成功破案的报道也在成倍增加。这表明法医昆虫学作为一门学科的兴起已日趋成熟,并作为一项应用技术已受到国际…     

嗜尸性昆虫证据在案发现场的分布研究

为了明确案发现场昆虫证据的分布,为法医昆虫学现场昆虫证据收集提供借鉴,我们利用猪尸体进行模拟,对现场昆虫的分布进行了调查,重点观察了大头金蝇、丝光绿蝇、绯颜裸金蝇、厚环黑蝇、阎甲科、隐翅甲科、埋葬甲科和皮蠹科昆虫的活动情况。结果表明,昆虫标本主要分布于尸体上及现场约10米范围的地面和地下,据此我们提出了法医昆虫学现场取样规范。     

贵州地区嗜尸蝇类调查

目的　调查贵州地区与尸体有关的蝇类。方法　根据昆虫学调查方法 ,设定调查地域 12个 ,于 2月、 5月、 8月和 11月的 10～ 2 0日采集一次标本。结果　全年 12个地域 44次共采集嗜尸蝇类标本 3 743 3只 ,经鉴定隶属于 5科 17属 2 7种。结论　取得了贵州地区嗜尸蝇种及区域、季节分布的资料 ,填补了在《中国蝇类》中未见贵州报道的空白。为下一步研究各嗜尸蝇种的生活史打下了基础 ,为推测死者的死亡季节及死亡环境提供参考依据。     

温度对丝光绿蝇幼虫发育速度影响

丝光绿蝇（Luciliasericata），属丽蝇科，俗称绿豆蝇，是一种分布极广的冈食性蝇类，主要李生在腐败动物质中，是尸体腐败过程中最常见的蝇种[1]。其生活史中经历有蝇（成虫）→卵十幼虫（蛆）→蛹→蝇的过程。根据尸体上该蝇种生活史的不同阶段特点，可以推断尸体的死亡时间。目前国外已有在实验室条件下观察记录蝇类生活史为主的基础研究报告[2，5]，但在国内尚未见有关报道。本文选择尸体腐败过程中最常见的丝光绿蝇为对象，研究其在8种实验恒温条件下生长发育速度．并取得基础数据，现报告如下。材料和方法将家兔处死后，放置于室外让…     

基于翅脉的图像数字化分析进行嗜尸性蝇类种类鉴定

目的基于翅脉的图像数字化分析对常见嗜尸性蝇类进行种类鉴定,为法医昆虫学中嗜尸性蝇类快速、准确的物种鉴定提供新的思路。方法用腐肉野外随机诱捕棕尾别麻蝇、绯角亚麻蝇、酱亚麻蝇、拟东方辛麻蝇、红尾粪麻蝇、巨尾阿丽蝇以及裸芒综蝇7种常见的嗜尸性蝇类雌雄成虫共226只,对每只苍蝇右翅的17个标志点进行数字化处理和图像分析,利用置换检验评估异速生长效应的影响,典型变量分析(canonical variate analysis,CVA)对7种嗜尸性蝇类物种间以及雌性物种间的翅形变化情况进行分析,交叉判别验证对分类的可靠性进行评价。结果在7种嗜尸性蝇类物种间和雌性成虫物种间,异速生长的影响具有统计学意义(P0.05)。CVA结果表明在7种嗜尸性蝇类物种间和雌性物种之间,翅膀形状变化具有明显的差异性,前2个典型变量占据了翅脉形状总变异的82.9%和84.1%。利用翅脉的图像数字化分析可以区分这7种常见的嗜尸性蝇类,总体种类判别准确率为81.2%～100.0%,7种雌性蝇类的种类判别准确率为75.0%～100.0%。结论基于翅脉的图像数字化分析是一种较为简便、可靠的昆虫物种鉴定的方法,可用于常见嗜尸性蝇类的种类鉴定。     

河南三门峡地区夏秋季常见嗜尸性蝇类的初步研究

目的探讨三门峡地区常见嗜尸性苍蝇种类、演替规律及其在法医学实践中的应用价值。方法采用笼诱法观察7月中旬-10月中旬兔尸上嗜尸性苍蝇种类演替规律及生活习性。结果出现的双翅目嗜尸性苍蝇有3科9属13种,主要为蝇科的舍蝇、市蝇、厩腐蝇、元厕蝇、斑蹠黑蝇、兰翠蝇;丽蝇科的大头金蝇、丝光绿蝇、亮绿蝇、巨尾阿丽蝇;麻蝇科的棕尾别麻蝇、褐须亚麻蝇和尾黑麻蝇;且出现时间有很强的规律性。结论河南三门峡地区夏秋季常见嗜尸性蝇类在兔尸上的出现有一定的演替规律,可望为该地区法医学死亡时间的推断提供参考。     

北京地区尸生性蝇类研究及其在法医鉴定中的应用

为提供法医学尸体死亡时间鉴定的准确性，对北京地区人尸上蝇类区系进行了系统调查（1994～1996）。发现本地区共有双翅目尸生性蝇类3科、12属、14种。其中常见种有红头丽蝇、丝光绿蝇、大头金蝇、肥须亚麻蝇、急钓亚麻蝇、棕尾别麻蝇和家蝇7种。对其常见种的幼虫进行不同温度和湿度下培养，观察常见环境因素，如日历期、风雨天气等因素对其生长发育速率的影响。结果表明，蝇类幼虫在其适宜生长发育的温度范围内，随着温度的升高发育速率加快，历期缩短；在同一温度和同一饲养条件下，发育速率因种而异；平均温度在28℃左右时，蝇类幼虫发育最快，尤其是1～2龄幼虫，时间为1天左右，且较稳定。这些数据对法医学推断死亡时间具有参考价值。     

In Vitro Effects of Household Products on Calliphoridae Larvae Development: Implication for Forensic Entomology

Several parameters can delay the first arrival of flies on a corpse and the subsequent development of the larvae. This study focuses on the development of Lucilia sericata (Diptera: Calliphoridae) (Meigen, 1826) on household chemical‐contaminated substrates. bleach, perfume, hydrochloric acid, caustic soda, insecticide, mosquito repellent, and gasoline in quantities consistent with an amount that could possibly be spilled on a corpse were mixed with beef liver to simulate contaminated fleshes. Larvae were bred at 25°C on these media until emergence. Four developmental parameters were followed: survival rates, development times, sex ratios, and adult sizes. Hydrochloric acid, insecticide, and gasoline killed all larvae. In low quantities, caustic soda and mosquito repellent increased the development time and decreased the adult size. However, high quantities of these chemicals killed all larvae. Lastly, bleach and perfume did not affect the survival rate and barely impacted the development time or adult size. These results demonstrate common household products spilled on a corpse can strongly affect the development of Calliphoridae larvae. The effects of such products should be considered in forensic entomology cases.     

Diurnal and Nocturnal Flight Activity of Blow Flies (Diptera: Calliphoridae) in a Rainforest Fragment in Brazil: Implications for the Colonization of Homicide Victims

Nocturnal flight of blow flies (Diptera: Calliphoridae) is a controversial issue in forensic entomology. We performed two field experiments to investigate the diurnal and nocturnal activity of six blow fly species in a rainforest fragment in Brazil. Initially, nocturnal (17:30–05:30) versus diurnal (05:30–17:30) flight activity was investigated. Only 3.9% of adults were collected at night, mostly the native species Mesembrinella bicolor, and nocturnal oviposition did not occur. In the second experiment, collection of adults took place at the following intervals: 05:30–08:30, 08:30–11:30, 11:30–14:30, and 14:30–17:30. The proportions of adults did not differ significantly among the four diurnal intervals, except for Hemilucilia segmentaria, which was captured more frequently in the early morning. Calliphoridae has predominantly diurnal behavior, not laying eggs in darkness. The association of the native species M. bicolor, Hemilucilia semidiaphana, and H. segmentaria to forested areas reinforces the forensic relevance of data on their flight pattern.     

PCR-RFLP identification of Diptera (Calliphoridae,Muscidae and Sarcophagidae)--a generally applicable method

A simple, rapid method using restriction fragment length polymorphisms (RFLPs) within the internal transcribed spacer (ITS) regions of the ribosomal DNA gene repeat allows identification of insects and other organisms. We used the method to identify the morphologically similar Diptera larvae that are important in forensic entomology for estimating the time and location of death. Polymerase chain reaction (PCR) was used to amplify a region from the 18S to the 28S rRNA genes. The ITS1 and ITS2 regions provided variation between species and homogeneity within species, with the exception of Cochliomya macellaria. Combinations of the restriction enzymes DdeI, HinfI and Sau3AI provided diagnostic bands for identification of the ten species from three families of Diptera (Calliphoridae, Muscidae and Sarcophagidae).     

A forensic entomology case from the Amazon rain forest of Brazil

The first case of application of forensic entomology in the Brazilian Amazonia is described. The corpses of 26 men were found in the rainforest in Rondonia State, Brazil. Fly larvae collected on the bodies during autopsy were identified as Paralucilia fulvinota (Diptera, Calliphoridae). No data or specimens were collected at the crime scene. At the laboratory, the larvae developed into pupae in 58 h and into adults in 110.5 h. The total development time for P. fulvinota was measured in field experiments inside the forest. The age of the larvae when collected from the bodies was estimated as the difference between the time required for them to become adults and the total development time for this species. The estimated age of the maggots and the minimum postmortem interval was 5.7 days.     

Hydrocarbon and Fatty Acid Composition from Blowfly Eggs Represents a Potential Complementary Taxonomic Tool of Forensic Importance,

One of the most important contributions of forensic entomology is to assist criminal expertise to determine the postmortem interval, which depends on the duration of the immature stages of insects of forensic interest. On the other hand, the time of development of the different stages varies according to the species; therefore, its identification is essential. Currently, few studies have investigated the use of cuticular hydrocarbons, and none regarding fatty acids, as complementary taxonomic tools to expedite species identification. Therefore, we evaluated whether cuticular hydrocarbons together with fatty acids of eggs of flies of the family Calliphoridae, main group of forensic interest, can be used to distinguish species. The analyses were performed by chromatographic techniques. The results show that there are significant differences between the composition of cuticular hydrocarbons and fatty acids between species and, therefore, they can be used to provide a complementary taxonomic tool to expedite the forensic expertise.     

The development of the black blow fly, Phormia regina (Meigen).

The black blow fly, Phormia regina (Meigen) is a primary species commonly utilized to indicate a postmortem interval, or more appropriately a "time since colonization". Due to the importance of this species as a secondary myiasis producer in livestock operations, and more recently as a time since death indicator in the field of forensic entomology, a considerable amount of data on its growth and development has been generated. However, the developmental time as reported by these studies varies greatly, and current more detailed data is needed for use in medicocriminal entomology. Hourly developmental data is presented under constant temperatures of 10, 15, 20, 25, 30, 35 and 40 degrees C, and cyclic temperatures of 10-15, 15-25, 25-35 and 35-45 degrees C. This study is in agreement with the results reported by Kamal [Comparative study of thirteen species of sarcosaprophagous Calliphoridae and Sarcophagidae (Diptera). I. Bionomics, Ann. Entomol. Soc. Am. 51 (1958) 261] and Melvin [Incubation period of eggs of certain musciod flies at different constant temperatures, Ann. Entomol. Soc. Am. 27 (1934) 406] only at temperatures of 25 degrees C and below. Bishopp [Flies which cause myiasis in man and animals: some aspects of the problem, J. Econ. Entomol. 8 (1915) 317] reported a shorter developmental duration for larval stages than what was produced with our laboratory rearings.     

Genetic relationships between blowflies (Calliphoridae) of forensic importance.

Phylogenetic relationships among blowfly (Calliphoridae) species of forensic importance are explored using DNA sequence data from the large sub-unit (lsu, 28S) ribosomal RNA (rRNA) gene, the study includes representatives of a range of calliphorid species commonly encountered in forensic analysis in Britain and Europe. The data presented provide a basis to define molecular markers, including the identification of highly informative intra-sequence regions, which may be of use in the identification of larvae for forensic entomology. Phylogenetic analysis of the sequences also provides new insights into the different evolutionary patterns apparent within the family Calliphoridae which, additionally, can provide a measure of the degree of genetic variation likely to be encountered within taxonomic groups of differing forensic utility.     

Wildlife forensic entomology: determining time of death in two illegally killed black bear cubs.

Forensic entomology is now commonly used to determine time of death in human death investigations. However, it can be equally applicable to wildlife crimes. This paper describes the use of entomology to determine time of death in the illegal killing of two young bear cubs in Manitoba, Canada. Two cubs were found shot, disemboweled, with their gall bladders removed. Natural Resource officers (Conservation Officers) and a Royal Canadian Mounted Police (R.C.M.P.) officer examined the remains, and the R.C.M.P. officer collected insect evidence. The only insects on the remains were adult blow flies coming to lay eggs and the blow fly eggs themselves (Diptera: Calliphoridae). The time of hatch was recorded and the insects were reared to adulthood. Time of hatch, together with species identification, macro and micro climate and lab developmental data were used to determine the time of death. The time was consistent with the time that the defendants were seen at the scene and was used in their conviction. This case illustrates that insect evidence can be equally as valuable in poaching cases as in homicide cases. However, in most cases Conservation Officers are unaware of this science. It is therefore, extremely important for more Conservation Officers to be educated about this field.     

尸源性昆虫的法医学研究进展

尸源性昆虫学是应用昆虫学知识解决有关法律问题的法医学分支学科,对死亡时间的推断。特别是腐败尸体的死后间隔时间的推断等方面具有无可比拟的优越性。本文根据国内外近期法医昆虫学方面的研究进展,阐述了尸源性昆虫的研究历史、种类和侵蚀过程,并总结了尸源性昆虫形态学及分子生物学的种属鉴定方法。及近几年来在推断死亡时间方面的具体应用。就尸源性昆虫在法医学领域内的应用及进展进行综述。