Carrion flies of forensic interest: a study of seasonal community composition and succession in Lisbon, Portugal

Abstract

Information on Diptera community, seasonality and successional patterns in every geographical region is fundamental for the use of flies as forensic indicators of time of death. In order to obtain these data from the Lisbon area (Portugal), experiments were conducted during the four seasons of the year, using piglet carcasses as animal models. Five stages were recognized during the decomposition process. The stages, besides visually defined, could be separated taking into account the occurrence and abundance of the specific groups of Diptera collected. In general, the bloated stage recorded higher abundance and species-richness values. Seventy-one species were identified, belonging to 39 families, in a total of 20 144 adult Diptera collected. Autumn yielded the highest values of species richness, whereas winter had the lowest. In all seasons of the year, Calliphoridae was the dominant family; Muscidae and Fanniidae were very abundant as well. Calliphora vicina Robineau-Desvoidy, Calliphora vomitoria (Linnaeus), Chrysomya albiceps (Wiedemann), Lucilia ampullacea Villeneuve, Lucilia caesar (Linnaeus), Lucilia sericata (Meigen) (Calliphoridae), Hydrotaea ignava (Harris), Muscina prolapsa (Harris), Synthesiomyia nudiseta (van der Wulp) (Muscidae), Piophila megastigmata McAlpine, Stearibia nigriceps (Meigen) (Piophilidae) and Nemopoda nitidula (Fallén) (Sepsidae) were revealed to be very important members of the Diptera community collected. The necrophagous behaviour, demonstrated by their immatures, using carrion as a food source makes them useful forensic indicator species. Also of relevance is the presence of Chrysomya megacephala (Fabricius), S. nudiseta and P. megastigmata, foreign species established in the local carrion communities. This study also marks the first record of S. nudiseta in Portugal.

Small Bait Traps as Accurate Predictors of Dipteran Early Colonizers in Forensic Studies

“…The occurrence of carrion flies was clearly influenced by temperature effects, as expected from the literature (Tantawi et al 1996;Martínez-Sánchez et al 2000;Schrӧeder et al 2003;Arnaldos et al 2004;Grassberger and Frank 2004;Hwang and Turner 2005;Anton et al 2011;Battán Horenstein and Salvo 2012;Prado e Castro et al 2012;George et al 2013). The highest number of specimens and species was caught with a high average air temperature, while the lowest values were obtained in low temperatures, which is in agreement with the results obtained from western Spain by Martínez-Sánchez et al (2000).…”

“…Conversely, most of the Diptera species from family Muscidae documented on the first seven days in carcasses in Salamanca (Martínez-Sánchez et al 2000) were not part of the insect fauna of our study. Although, the study performed in Murcia (Arnaldos et al 2004) and the one performed in Lisbon (Prado e Castro et al 2012) found the same species of muscid flies as the ones found in this study, except for the species H. dentipes was collected in Prado e Castro et al 2012 but not here, and a trade in the genera Phaonia, as the present study collected the species Phaonia trimaculata and Prado e Castro et al collected P. subventa (Table 6). These results suggest that forensically important Muscidae communities are more region-specific and/or more bait sensitive than Calliphoridae.…”

“…In fact, the traps used in this study, as well as the experimental design, captured the same diversity of Diptera early colonizers when compared with studies using pig carcasses in the same region (Prado e Castro et al 2012). Moreover, this kind of trap is cheap, easy to make and replicate, and does not have the ethical, legal, or practicability implications associated with the use of human remains or pig carcasses.…”

“…Nevertheless, all blowfly species, except for Chrysomya megacephala, which was collected on pig carcass in Lisbon (Prado e Castro et al 2012) and also on chicken carcass in Murcia, Southeast Spain (Arnaldos et al 2004), were also collected in the present study. It is important to highlight that C. megacephala is a species only recently discovered in Portugal and in low numbers (Prado e Castro and García 2009).…”

The colonisation of remains by the muscid flies Muscina stabulans (Fallén) and Muscina prolapsa (Harris) (Diptera: Muscidae)

“…[17]. A similar distribution pattern has been described in Lisbon in Portugal although somewhat fewer M. stabulans were recorded in summer than in the spring and autumn [18]. Skidmore (1985) [11] [21] although some authors state that state that they usually overwinter as pupae [22].…”