Diptera Succession during Early Decomposition Stages in a Mediterranean Pinewood Umbrage

Research Article

Austin J Forensic Sci Criminol. 2015; 2(4): 1033.

Diptera Succession during Early Decomposition Stages in a Mediterranean Pinewood Umbrage

Arnaldos MI1,2, Khedre A³, Begoña I¹, Presa JJ¹, Clemente ME¹, López-Gallego E¹, Martínez AB¹, Pérez-Marcos M¹ and García MD1,2*

¹Department of Zoology and Physical Anthropology, University of Murcia, Spain

²Servicio Externo de Ciencias y Técnicas Forenses, University of Murcia, Spain

³Department of Zoology, University of Sohag, Egypt

*Corresponding author: Maria Dolores Garcia, Department of Zoology and Physical Anthropology, Campus Universitario de Espinardo, 30100 Murcia, Spain

Received: July 16, 2015; Accepted: August 09, 2015; Published: August 12, 2015


The succession of entomosarcosaprophagous fauna depends on multiple factors, being the environment one of the most important. Thus the study of sarcosaprophagous community in different microclimatic environments is relevant, even if the different locations are close to each other. Results concerning the early sarcosaprophagous community collected during a whole year in an umbrage area located at 980 MASL in Sierra Espuña Mountain (Murcia province, SE Spain) are presented. The study was carried out using a Schoenly trap baited with 5kg piglets. A daily sample was taken during all four seasons. More than 12700 specimens, belonging to 18 orders of Arthropoda, were collected. The most abundant in all seasons was Diptera, representing 97.66% of the captures in fall. Among Diptera, Calliphoridae was the most representative family during the first stages of decomposition, representing 94.37% of all Diptera in spring, 41.05% in summer, 61.03% in fall and 80% in winter. Muscidae and Fannidae were also abundant in summer and fall. The Calliphorid species collected were: Calliphora vicina, Calliphora vomitoria, Chrysomya albiceps, Lucilia caesar, Lucilia sericata, Pollenia sp. and Stomorhina lunata. The primary species was always C. vicina. The most abundant species in the whole study was Chrysomya albiceps, being the most representative species in summer and fall. Calliphora vicina was the most representative in spring and winter. These results are compared with previous studies conducted with a piglet and chicken carcasses in a near suburban area. Differences concerning community species composition and dynamics and succession, as well as decomposition process have been detected.

Keywords: Calliphoridae; Forensic entomology; Iberian Peninsula; Sarcosaprophagous fauna


Studies on the entomosarcosaprophagous community and the successional patterns in carcasses represent the starting point of research in forensic entomology that mainly deals with death investigations. One of the methods to estimate the delay between death and corpse finding is based on the biological principle of succession, where the colonization of the corpse occurs in a sequence that, when known, is predictable. Successional stages are represented by the variety of arthropods present in the corpse at a particular time. This diversity is, then, compared to know successional patterns for that geographic area or habitat [1]. Unfortunately, most of the studies concerning the sarcosaprophagous community and its successional patterns have been conducted in restricted areas, mainly man influenced, and few comparisons with other close and different environments have been made. In particular, wild areas have been ignored, except for some locations [1-10].

In the Iberian Peninsula, except for some data [3,4,11-15], hardly any work has been devoted to natural environments related to the sarcosaprophagous community. With exception of the information on diversity of species and relative abundance of taxa obtained from succession studies [16] no other data exists about sarcosaprophagous succession in wild conditions in the Iberian Peninsula.

As it concerns the community, the most important component for forensic purposes is the necrophagous, mainly Diptera, some of which are known to be the first arthropods to arrive at the corpse. These insects arrive immediately after death, and their dynamics depend on several factors [17], such as the corpse placement, weather conditions, and season. In addition, the corpse itself is an important factor [18-20].

Given all of above, our study attempts to provide for the first time data, for the Iberian Peninsula and also Europe, on the early sarcosaprophagous community in a mountainous wild environment.

Materials and Methods

The present study was carried out in the Murcia region of Sierra Espuña, a mountainous area located in the southeast of the Iberian Peninsula (SE Spain). The selected location was an umbrage area named Peña Apartada, at 980 MASL (UTM 30TXG6274190).

The vegetation of the area is a mixed mediterranean forest composed of Pinus halepensis, Pinus pinaster, Pinus nigra, Quercus rotundifolia, Quercus faginea, Quercus coccifera, Juniperus oxycedrus and Pistacia lentiscus.

Samples were collected daily for 15 days during the four seasons of the year defined as fall (15/09/06-29/09/06), winter (8/01/07- 22/01/07), spring (4/04/07-18/04/07) and summer (15/06/07- 29/06/07).

A modified version of the trap designed by Schoenly et al. [21] measuring 60 × 70 × 70 cm and Morril solution [22] as preservative solution were used to collect sarcosaprophagous fauna. This trap has been used previously for the study of sarcosaprophagous fauna [23-30], and has been shown to be as effective as other conventional methods by Ordóñez et al. [31].

Each season the trap was baited with a dead piglet (Sus scrofa L.) of 5kg weight. The piglet was euthanized using ketamine and saline solution, according to European Convention for the Protection of Vertebrate Animals used for Experimental and Other Scientific Purposes (86/609/CEE) D.O.C.E. 18.12.86. The piglets were provided by the University of Murcia Veterinary farm. As soon as the animals died, they were covered by a plastic bag to protect them during transportation to the trap.

The relative humidity and the temperature inside the trap were continuously recorded with HOBO U1O Data loggers placed in the trap.

Each sampling day, digital photographs of the bait were taken, and any other relevant data related to weather conditions, odours, etc. were also recorded.

Insect taxa were identified using different keys [32-35].

To estimate the diversity of Diptera community in our study, Margalef and Shannon indexes were calculated for each season, and for every decomposition stage. Margalef index was calculated following the equation MI=(S-1)/lnN, where S is the number of identified taxa and N is the total amount of individuals. Shannon’s index was calculated from the equation: H’=-Σ pi ln pi, where pi is the proportion of individuals found in the ith species from the total pool of species. The importance, utility and characteristics of both indexes have been extensively discussed in Magurran [36] and in Prado e Castro (pers. comm.) regarding the sarcosaprophagous community. Although the value of the Shannon index usually falls between 1.5 and 3.5 [36], the special characteristics of the sarcosaprophagous community made this index to achieve lower values, as reported in other special communities.

Results and Discussion

Climatological data

During fall, mean temperatures were quite warm (17-22oC); relative humidity varied between 43 and 89% (Figure 1). In winter, mean temperature decreased reaching a minimum of 4.5°C and a maximum of 13.5oC. Relative humidity was close to 50% reaching 70% around the middle of the sampling period. Spring was characterized by low mean temperatures, close to 10oC, and relative humidity close to 50% except for the first days. During summer, mean daily temperature was close to 23oC; relative humidity reached values in the upper 50%, increasing towards the end of the sampling period.