Diversity of the Formicidae (Hymenoptera) carrion communities in Lisbon (Portugal): preliminary approach as seasonal and geographic indicators

Abstract

The value of the Formicidae (Insecta, Hymenoptera) community in forensic investigations is poorly studied in Portugal. In order to better understand the structure and dynamics of this group of insects in cadavers and their putative value in forensic investigations, studies were carried out in Lisbon area during one year. Piglet carcasses were used as a model of human decomposition. The entomofauna attracted to the carcasses was collected over a period of about 2 months in each season of the year. The collection of ants was performed at regular intervals, daily in the first 23 days and then with intervals of 2, 3 or 5 days until the end of the experiment. Five stages of cadaveric decomposition were recognized with the ants being present in all of them. Three hundred and nine specimens were captured: 7 in autumn, 6 in winter, 90 in spring and 206 in summer. These specimens belong to three subfamilies and seven different species. Four of them had never been mentioned before as being associated to cadavers in this geographical area. Spring and summer had the greater diversity of species and a larger number of individuals. Temnothorax luteus was the dominant species in spring and Tapinoma nigerrimum in summer. Corroborating the information of other similar studies carried out in the Iberian Peninsula, the sarcosaprophagous Formicidae community found in Lisbon is unique and different from other studied locations, which supports the need to perform regional studies. Our results shown that ants do not present a definite pattern of succession, but some species have the potential to be seasonal or geographic indicators.