新乡地区夏季常见嗜尸性昆虫群落演替规律初步研究

目的研究新乡地区夏季嗜尸性昆虫的种类及其群落演替规律。方法观察法研究新乡医学院动物房后偏僻草地上6只大白鼠和5只家兔尸体腐败过程中嗜尸性蝇类的主要物种及其群落演替规律。结果该地区主要出现嗜尸性蝇类为双翅目3科7种,包括家蝇、大头金蝇、丝光绿蝇、棕尾别麻蝇、黑尾黑麻蝇、厩腐蝇、元厕蝇,且呈现出演替规律性。结论研究结果可作为新乡地区对尸体死亡时间的推断依据。     

嗜尸性昆虫群落演替及其法医学应用研究进展

法医昆虫学是近年来法庭科学中发展较快的学科之一,而利用昆虫学证据来推断死亡时间或称死后经历时间(PMI)是其最主要的应用。当尸体PMI达一周以上,无法通过蝇蛆生长发育历期来推算时,仍可以借助嗜尸性昆虫群落演替规律来判断。嗜尸性昆虫群落演替规律与尸体腐败过程息息相关,法医昆虫学家通过对尸体腐败进行人为分期,能够辨别出不同的演替波次,从而达到推断PMI的目的。本文对嗜尸性昆虫群落演替研究与应用进行了综述,并分析了未来研究趋势,希望能为相关研究和实践应用提供参考。     

石家庄地区夏秋季常见嗜尸性昆虫群落演替规律

目的研究石家庄地区常见嗜尸性昆虫种类及其群落演替。方法观察法研究2007—2009年夏秋季放置在同一地点的9只家兔尸体上常见嗜尸性昆虫的种群演替。结果该地区家兔尸体上出现常见双翅目3科4属9种,主要有蝇科的家蝇、厩腐蝇、开普黑蝇、厚环黑蝇;丽蝇科的丝光绿蝇、大头金蝇,麻蝇科的棕尾别麻蝇、肥须亚麻蝇、黑尾黑麻蝇。鞘翅目5科11种,主要有埋葬甲科的大黑葬甲、Silpha carinata（Herbst）、大负葬甲、Ptomascopus morio（Kraatz）、双色葬甲;蜣螂科的金龟子;步甲科的毛婪步甲和蠋步甲;拟步甲科的细土潜;隐翅甲科的大黑隐翅虫、小隐翅虫。膜翅目2科2种,蚁科的路舍蚁;胡蜂科的墨胸胡蜂。结论该地区嗜尸性蝇类群落演替明显,嗜尸性昆虫有地域特征。研究结果可作为石家庄地区对尸体进行死亡时间推断的依据。     

深圳地区大头金蝇年生长发育规律观察

目的观察深圳地区优势嗜尸性蝇种大头金蝇在尸体腐败分解过程中的发育历变化规律,并探讨其用于死亡时间推断的可能性。方法在调查深圳地区嗜尸性昆虫物种谱系的基础上,设置自然环境下的家猪尸体腐败模型,观察记录大头金蝇到达尸体、蝇蛆出现、大量出现、开始离食、大量离食、开始化蛹、大量化蛹,蛹开始羽化和大量羽化9个发育历期关键时间点。同时,收集处理成虫和幼虫,测量体长并模拟二元方程用于死亡时间推断。结果深圳地区不同季节中,大头金蝇在尸体上的生长发育具有规律性,蛆虫的离食时间点和羽化时间点对应的腐败分期在各个季节基本相同,前者基本处于腐败期,后者处于后腐败期。该地区四季蝇蛆长随死亡时间的变化模拟成二项式方程,分别为春季:y=-0.000 2x2+0.147 5x-0.925(R2=0.989 3);夏季:y=-0.001 4x2+0.316 6x-4.499 8(R2=0.970 1);秋季:y=-0.000 4x2+0.187 8x-1.107 9(R2=0.987 8);冬季:y=0.000 4x2-0.080 3x+4.367(R2=0.994 9)。结论大头金蝇在尸体上发育历期有一定的规律性,特别是蛆虫的离食时间点和羽化时间点对死亡时间推断的参考价值。     

西藏自治区中南部地区嗜尸性蝇类种类组成及分布

死亡时间(postmortem interval,PMI)推断一直是涉及人员死亡的刑事案件现场勘验中法医调查的重点和难点[1]。嗜尸性蝇类证据的应用是解决死亡时间推断特别是腐败尸体死亡时间推断的有效手段之一,但前提是要立足案发当地常见嗜尸性蝇类的种类及分布特点,并据此建立具体种类的发育史数据库。     

青岛地区常见嗜尸性蝇种及其季节性分布研究

目的观察青岛地区嗜尸性蝇种季节性演替规律,为死亡时间推断提供参考。方法在室外设立田间观察场所,2012年4月1日开始至2013年4月1日,每月第1天6时放置猪尸,20min后开始观察,至18时,期间每小时观察1次;第3天以后,分别于7时、12时、18时各观察1次。观察时记录尸体上出现的昆虫种类、虫态、数量并采集相应标本,进行分类鉴定。结果可以观察到有嗜尸性蝇类侵袭尸体的月份为4月至11月,共发现3科23种蝇类,其中丝光绿蝇、大头金蝇和亮绿蝇数量位列前三,分别占全部观察数量的40.71%、31.95%和7.12%。丝光绿蝇、大头金蝇中午时段出现的数量显著多于早上和傍晚。一年中各种蝇类在中午出现的数量均多于早上及晚上。4月上旬,蝇类早、晚与中午出现的数量相差显著;而在7、8月份差别较小。大部分嗜尸性蝇种集中在新鲜期和肿胀期。结论本文观察数据可为利用嗜尸性蝇类演替规律进行法医学死亡时间推断,以及建立地区嗜尸性蝇种类数据提供参考。     

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。     

呼和浩特夏秋季嗜尸性苍蝇群落组成与演替

目的研究呼和浩特夏秋季常见嗜尸性苍蝇生态群落组成与演替规律。方法连续3年用观察法研究7—10月份,家兔、狗尸体、鸡、鱼内脏等试验材料上的嗜尸性苍蝇生态群落组成与演替。结果该地区上述尸体上出现的双翅目嗜尸性苍蝇是最先到达尸体上的昆虫,而且在尸体上出现时间及部位表现出很强的生态群落演替规律性。结论研究结果可成为在呼和浩特地区对尸体进行死亡时间、死亡地点推断的依据。     

北京地区法医昆虫学研究──Ⅱ.尸体分解过程中的昆虫种类演替与死亡时间推断

在调查北京地区嗜尸性昆虫物种谱系的基础上，进一步研究了在尸体分解过程中，昆虫种类的演替特点及其对死亡时间推断的价值。嗜尸性昆虫侵食尸体的过程可分为侵入期、分解期和残余期：侵入期以双翅目蝇类为主，时间推断以幼蛆的发育程度为依据；分解期出现大量鞘翅目种类，时间推断以甲虫的各类组成、数量以及演替特征为主要依据；残余期昆虫数量极少。季节及温度、环境条件、尸体是否受伤或裸露，是影响昆虫侵食尸体时序的三个重要因素。正常的春季，侵入期为8至25天，分解期为约42天。     

成都市嗜尸昆虫种类季节变化研究

目的 研究成都市嗜尸昆虫种类及其与季节变化的关系。方法 经过两年重复试验,观察3～11月兔尸上嗜尸昆虫种类变化。结果 发现3～11月兔尸上出现的嗜尸昆虫种类主要有舍蝇、丝光绿蝇、大头金蝇、赭尾麻蝇、巨阿尾丽蝇。其中,巨阿尾丽蝇见于3、4月,舍蝇出现于4月中旬至10月初,而大头金蝇、丝光绿蝇、赭尾麻蝇则自3月至10月中下旬均可见到,10月底以后则见不到任何嗜尸苍蝇。幼虫的出现晚于成虫1～4天不等,与季节及环境有关。结论 通过舍蝇、丝光绿蝇、大头金蝇、赭尾麻绳、巨阿尾丽蝇的生命周期的研究,有望为成都市法医学实践中死亡时间的推断提供依据。     

The succession and development of insects on pig carcasses and their significances in estimating PMI in south China

The succession of insect communities on carrion varies at local and global spatial scales. As such, ecological succession data obtained from corpses at one geographic location cannot necessarily be applied to other locations. Our study describes this succession in the far southern part of China to provide such data for forensic cases in this region. A total of 18 pig carcasses were placed in the field in four seasons, and the timing of the following events were recorded: appearance of larvae, onset of larval wandering, when most larvae had wandered, onset of pupariation, when most larvae had pupariated, onset of eclosion and end of eclosion. Our results indicated that all of the evaluated events could be used as accurate indicators of postmortem interval (PMI). The carcasses decayed fairly quickly in spring, summer and autumn, taking 225+/-75 h, 183+/-44 h, and 247+/-70 h, respectively, to decay from the fresh stage to skeletonisation. In winter, carcasses needed longer (1180+/-291) to decay as much. Carcasses attracted 47 species of insect, with flies predominating. The larvae were mainly Chrysomya megacephala (Fabricius), Chrysomya rufifacies (Macquart) and Hydrotaea (Ophyra) spinigera (Stein). Most necrophagous insects were found all year around, and there were no marked differences in species among the four seasons, except that Dermestes maculatus (De Geer) was absent in winter. Blowflies produced only one generation on a carcass before it became skeletonised, which simplified the estimation of PMIs.     

Preliminary study of the succession pattern of necrobiont insects, colonising species and larvae on pig carcasses in Temuco (Chile) for forensic applications

Knowledge regarding the succession patterns of insects that visit carcasses as well as the other arthropod that colonise them and analysis of the parameters that are associated with larvae allow calculation of the minimum postmortem interval (PMI). This information is obtained from experiments carried out under specific geoclimatic conditions, which determine their application in forensic environments under similar conditions. The field study presented here is the first in Chile to analyse the decomposition process of pig carcasses and the associated succession of insects, colonising species and parameters related to larval masses. All of the larvae obtained from daily samples were measured (in mm), and their mean, range, standard deviation and stage of development (instars) were determined. The carcasses reached the dry remains stage in only 11 days. Seven species of Diptera visited the carcass during the process, but only two species colonised it by means of egg deposition followed by development of larvae: Cochliomyia macellaria (Fabricius) and Lucilia sericata (Meigen) (Diptera: Calliphoridae), which exhibited a duration of the development cycle from egg to adult of 21 days. The collected Coleoptera correspond to five predator species (Staphilinidae and Histeridae). From the results of this study, it can be concluded that only some of the insect species present in this region can provide information that can be used in forensic entomology and that analysis of larval masses of colonising species can be a valuable tool for determining the PMI(min) in this region of Chile.     

Diversity of Forensic Rove Beetles (Coleoptera,Staphylinidae) Associated with Decaying Pig Carcass in a Forest Biotope

Most forensic studies are focused on Diptera pattern colonization while neglecting Coleoptera succession. So far, little information is available on the postmortem colonization by beetles and the decomposition process they initiate under temperate biogeoclimatic countries. These beetles have, however, been referred to as being part of the entomofaunal colonization of a dead body. Forensic entomologists need increased databases detailing the distribution, ecology, and phenology of necrophagous insects, including staphylinids (Coleoptera, Staphylinidae). While pig carcasses are commonly used in forensic entomology studies to surrogate human decomposition and to investigate the entomofaunal succession, very few works have been conducted in Europe on large carcasses. Our work reports the monitoring of the presence of adult rove beetles (Coleoptera, Staphylinidae) on decaying pig carcasses in a forest biotope during four seasons (spring, summer, fall, and winter). A total of 23 genera comprising 60 species of rove beetles were collected from pig carcasses.     

A preliminary investigation of insect colonisation and succession on remains in New Zealand

A preliminary, systematic field study on the process of decomposition and associated insects was conducted, for the first time, in New Zealand. Using pig carcasses as an animal model for human decomposition, insect colonisation and succession was monitored in three different habitats in the Auckland region where remains are likely to be found. A significant difference in the rates of decomposition was found among the three different habitats of an open field, coastal sand dune area and native bush during the autumn/winter season. The primary colonisers of all carcasses were Calliphora stygia Fabricius (Calliphoridae), Chrysomya rufifacies Macquart (Calliphoridae) and Hydrotaea rostrata Robineau-Desvoidy (Muscidae). Two species were identified as possible representatives of the habitats in which they were found; Fannia sp. (Fanniidae) in the open field habitat and Calliphora hilli Patton (Calliphoridae) in the native bush habitat. Also identified was Sylvicola sp. (Anisopodidae) as a possible indicator of damp habitats as well as a likely indicator of a longer postmortem interval. This preliminary investigation presents a broad outline of the insects associated with remains and the order in which they appear in the Auckland region.     

Insect succession and carrion decomposition in selected forests of Central Europe. Part 3: Succession of carrion fauna

The succession of insects on pig carrion was monitored in spring, summer and autumn, in three forest types and 2 years in Western Poland (Central Europe). In most forensically useful taxa, significant differences between seasons, forests and years in time of appearance on carrion were found. The lowest values of appearance time were recorded in summer and the highest in spring. In alder forest insects appeared on carcasses significantly earlier than in pine-oak forest and hornbeam-oak forest. In summer periods of insect presence on carrion were significantly shorter than in spring and autumn. In most taxa no significant effect of forest type or year on length of the presence period was found. In all seasons assemblages of adult taxa were clearly more aggregated than assemblages of larval taxa. Sequence of insects' appearance on carcasses was very similar in different seasons, forests and years. General seasonal models of insect succession on carrion are proposed for forests of Central Europe. Data on appearance time and length of the presence period in particular seasons, forests and years are presented for forensically useful taxa. Implications for methods of PMI estimation (particularly the succession-based method) are discussed.     

Variation in decomposition stages and carrion insect succession in a dry tropical climate and its effect on estimating postmortem interval

Insects have an important role in minimum postmortem interval (PMI_min) estimation. An accurate PMI_min estimation relies on a comprehensive study of the development and succession of local carrion insects. No published research on carrion insect succession exists for tropical north Queensland. To address this, we aimed to obtain preliminary observational data concerning the rate of decomposition and insect succession on pig carcasses in Townsville and compare these with other regions of Australia and overseas. Adult insects were collected daily from three pig carcasses for 30 d during summer and identified to family level. Observations of decomposition rate were made each day and progression through the stages of decomposition were recorded. Adult insects were identified to family and their presence/absence used as a proxy for arrival at/departure from the remains, respectively. These preliminary data highlight several interesting trends that may be informative for forensic PMI_min estimation. Decomposition was rapid: all carcasses were at the dry/remains stage by Day 5, which was substantially quicker than all other regions in the comparison. Differences were also observed in the presence/absence of insect families and their arrival and departure times. Given the rapid progression through early decomposition, we argue that later-arriving coleopteran taxa may be more forensically informative in tropical Australia, in contrast with temperate regions where Diptera appear most useful. This research contributes preliminary observational data to understanding insect succession patterns in tropical Australia and demonstrates the critical need for comprehensive local succession data for each climatic region of Australia to enable accurate PMI_min estimation. These data will inform future research targeted at gaining a more comprehensive understanding of insect succession in the Australian tropics.

Key points:

• We obtained preliminary observational data concerning the rate of decomposition and insect succession on pig carcasses in tropical Australia.
• Decomposition was rapid: all carcasses were at the dry/remains stage by Day 5.
• Coleopteran taxa may be more forensically informative in tropical Australia than dipterans.

     

Decomposition and Arthropod Succession in Whitehorse,Yukon Territory,Canada

Forensic arthropod succession patterns are known to vary between regions. However, the northern habitats of the globe have been largely left unstudied. Three pig carcasses were studied outdoors in Whitehorse, Yukon Territory. Adult and immature insects were collected for identification and comparison. The dominant Diptera and Coleoptera species at all carcasses were Protophormia terraneovae (R‐D) (Fam: Calliphoridae) and Thanatophilus lapponicus (Herbst) (Fam: Silphidae), respectively. Rate of decomposition, patterns of Diptera and Coleoptera succession, and species dominance were shown to differ from previous studies in temperate regions, particularly as P. terraenovae showed complete dominance among blowfly species. Rate of decomposition through the first four stages was generally slow, and the last stage of decomposition was not observed at any carcass due to time constraints. It is concluded that biogeoclimatic range has a significant effect on insect presence and rate of decomposition, making it an important factor to consider when calculating a postmortem interval.