Teresa Bonacci

Successional patterns of the insect fauna on a pig carcass in southern Italy and the role of Crematogaster scutellaris (Hymenoptera, Formicidae) as a carrion invader

The sarcosaprophagous fauna plays a key role in organic matter decomposition. Moreover, the biological, ecological and behavioral specificities of the taxa are useful to reconstruct the decay history of a corpse or carcass, often back to the lethal event. Here we report the seasonal succession of the insect fauna on a pig carcass exposed in a rural area in Calabria (southern Italy) during summer 2007 and 2008. The aim is to identify and qualitatively assess the major taxa of forensic importance in this region. The principal fly invaders were Lucilia caesar (L.), L. sericata (Meigen, 1826), Chrysomya albiceps (Wiedemann, 1819), Sarcophaga (Meigen, 1826) spp. and Amobia (Robineau‐Desvoidy, 1830) spp., Musca domestica (L.) and Muscina stabulans (Fallen, 1817). The primary beetle species collected in summer belonged to Dermestidae, Dermestes maculatus (De Geer, 1774) and Cleridae, Necrobia rufipes (De Geer, 1775). This paper also examined the ecological role of ants in the insect succession and describes the evidence of skin injuries directly inflicted by the acrobat ant Crematogaster (Acrocoelia) scutellaris (Olivier, 1791) (Hymenoptera Formicidae) while feeding on pig carrion. Ants belonging to two other species were also collected: Camponotus aethiops (Latreille, 1798) and Tetramorium semilaeve (André, 1881). Ants can invade carcasses and corpses directly, disrupting blowfly egg laying or preying on their larvae. Our data on the carrion faunal composition and role of ants as invaders should be useful for further forensic cases in Calabria (southern Italy). This is among the few reports of ants as forensically relevant species.

A case of Calliphora vicina Robineau-Desvoidy, 1830 (Diptera, Calliphoridae) breeding in a human corpse in Calabria (southern Italy)

Forensic entomology is the study of insects associated with human corpses. The most common and widely accepted application of entomological evidence in criminal investigations is to determine the post-mortem interval (PMI), i.e. the time from death to discovery of the corpse, and other circumstances of the crime scene. The insects that first colonize a human corpse usually belong to the families Calliphoridae, Sarcophagidae and Muscidae, and often are very important elements in forensic investigation. The aim of this study was to highlight the importance of evaluating forensic evidence on a regional and urban scale. To assess the climatic, geographical and environmental influences on carrion-breeding fauna, we present details of a case in Calabria (southern Italy) in February 2007. The entomological evidence consisted only of Calliphora vicina Robineau-Desvoidy, 1830. The presence of this species is related to the climatic and micro-environmental conditions in the urban habitat of Cosenza, southern Italy, and to the location and status of the cadaver.

Rediscovering the ‘umbrella species’ candidate Cucujus cinnaberinus (Scopoli, 1763) in Southern Italy (Coleoptera Cucujidae), and notes on bionomy

Abstract During the monitoring of protected species for the management plan of the Sila National Park (Calabria), abundant populations of the saproxylic beetle Cucujus cinnaberinus were recorded in some pSCI forest sites with a well-developed Pinus nigra laricio tree layer. The beetle was rediscovered in Calabria after 49 years of unsuccessful attempts (since 1960) in 7 of the 21 stands investigated; it seems to be concentrated in good quality biotopes marked by a high availability of fallen pine trunks at least 30 cm in diameter. In May and June, the population is represented mostly by aged larvae (III, IV instar), and pupae have been obtained in the laboratory starting from July. The observed feeding habits are predatory on maggots and on larvae of other saproxylic beetles; thus, C. cinnaberinus can be defined as a very active ‘large spectrum predator of saproxylic arthropods’. Chopped veal could be an alternative larval food in the laboratory. Climatic oscillations (annual precipitation) may be involved in the reappearance of the beetle. A preliminary list of the associated saproxylic fauna is presented and the potential role of C. cinnaberinus as an umbrella species is discussed.

A preliminary investigation of insect succession on carrion in Calabria (southern Italy)

We present data from the first study of successional patterns of insect fauna in Calabria (southern Italy). The aim was to identify and qualitatively assess the major taxa of forensic importance in this region. Studies were conducted in autumn-winter 2006, summer 2007 and winter 2008 in the Botanical Garden, University of Calabria. Over 50 taxa were collected and identified. The most abundant fly species were Lucilia caesar (Linnaeus, 1758), L. sericata (Meigen, 1826), Chrysomya albiceps (Wiedemann, 1819), Calliphora vicina Robineau-Desvoidy, 1830, C. vomitoria (Linnaeus, 1758), Sarcophaga spp., Amobia sp ., Musca domestica Linnaeus, 1758, and Muscina stabulans ((Fallen). The successional patterns, relative abundance of adult sarcosaprophagous insects, carcass decay, diversity and seasonality of species are described and the taxa useful for estimating the post-mortem interval (PMI) are identified. The data of this study could be very useful for further forensic investigations in southern Italy.

Testing the predatory behaviour of Podarcis sicula (Reptilia: Lacertidae) towards aposematic and non-aposematic preys

Food preferences and the effects of prey chemical repellents in the dietary behaviour of Podarcis sicula were tested using four species of Carabid beetles as prey models. The goal of the study was to assess (i) the ability of P. sicula to recognize insect preys provided with chemical repellents and aposematic colorations under laboratory conditions, and (ii) the importance of chemical signals used by the prey model as antipredatory strategy. Preys used in this study were Brachinus sclopeta and Anchomenus dorsalis (aposematic species) and Amara anthobia and A. aenea (non-aposematic species). Aposematic species are characterized by warning color pattern and by production of chemical repellents, while non-aposematic ones do not. Amara anthobia and A. aenea were attacked with high frequency by P. sicula, Brachinus sclopeta and Anchomenus dorsalis with low frequency. Non-aposematic species were preyed more often than the aposematic ones. Brachinus sclopeta was preyed after low latency, while Amara anthobia and A. aenea after long latency. Non-aposematic species were captured and eaten without difficulty, while when B. sclopeta or A. dorsalis were captured, lizards always tossed their head and then rub the snout on the soil, probably because of the unpalatability of aposematic preys.

Cucujus tulliae sp. n. – an endemic Mediterranean saproxylic beetle from genus Cucujus Fabricius, 1775 (Coleoptera, Cucujidae), and keys for identification of adults and larvae native to Europe

Abstract Cucujus tulliae sp. n. is described as a new member of genus Cucujus Fabricius, 1775 (Coleoptera, Cucujidae), which enumerates at present eleven species distributed in Eurasia and northern America. This saproxylic beetle is the first Cucujus species known only from Mediterranean and it is probably endemic to Calabria (Italy). The species was found especially in old–growth mountain forests of high conservation value (i.e. national parks) dominated by Calabrian pine (Pinus laricio calabrica). We hypothesize that Cucujus tulliae sp. n. probably evolved from isolated populations of Cucujus haematodes Erichson, 1845. The species is thus relictual and of high conservation value, corresponding at least to endangered (EN) category with respect to recent IUCN criterion. Cucujus tulliae sp. n. is here compared with two species native to Europe – Cucujus haematodes and Cucujus cinnaberinus (Scopoli, 1763) and with the Caucasian Cucujus haematodes caucasicus Motschulsky, 1845, which is confirmed as a valid subspecies. The male genitalia of this Caucasian form have been examined and illustrated for the first time. A comprehensive key to adults and larvae of European species is provided.

Peace in ground-beetle larvae: non-aggressive outcome in Chlaenius spp. larvae interactions

Cannibalism reduces the number of competitors and provides high-quality food, but it may have costs related to the risk of injury, disease/parasite transmission and reduction of inclusive fitness. Carabid larvae are usually very aggressive, with very low tolerance of conspecifics. Thus cannibalism is common. We investigated aggressive and cannibalistic behaviour in the larvae of eight ground beetle species, especially Chlaenius velutinus and Chlaenius spoliatus whose larvae have long articulated cerci. Chlaenius species live in dense populations with frequent intra-specific encounters, whereas encounters are rare in the other species. Dyads of conspecific larvae of the eight ground beetles species were tested for aggressive and cannibalistic behaviour. Unlike the other six species, larvae of the two Chlaenius species avoid cannibalism, possibly as a consequence of a behavioural display involving cerci interactions. This display was never recorded in conspecific larval interactions of the other species. Instead, cannibalism consistently occurred (20 to 50%) following aggressive interactions (1.2 to 2.6 attacks/event). The non-aggressive outcome in Chlaenius larval interactions contrasts with the high aggressiveness (35 to 85% of trials) shown by the other species. This suggests the presence of an inhibitory mechanism in the Chlaenius species. The cerci interaction probably inhibits cannibalism via intra-specific recognition; this behaviour may have evolved under the pressure of ecological factors (resource abundance and dispersion, larvae density, frequency of encounters). In Chlaenius spp. ecological constraints may have led to an inconvenient costs/benefits trade-off, while in other species they did not exert negative pressure on the occurrence of cannibalism.

Odour and Colour Similarity in Two Species of Gregarious Carabid Beetles (Coleoptera) from the Crati Valley, Southern Italy: A Case of Müllerian Mimicry?

ABSTRACT Bombardier beetles of the genus Brachinus (Carabidae) are disagreeable prey because they discharge irritating quinones. Brachinus beetles live in aggregations and display warning colours. Like Brachinus beetles, Anchomenus dorsalis beetles produce methylsalicylate, and present a similar colour pattern. Anchomenus dorsalis beetles are usually found within Brachinus aggregations. Our aim was to investigate the similarity of cuticular chemical profiles of these two species to test the hypothesis of interspecific chemical mimicry. We investigated the cuticular composition of A. dorsalis, B. sclopeta, and Poecilus cupreus. Poecilus cupreus, a non-aposematic carabid commonly found in Brachinus spp and Anchonemus dorsalis aggregations, was used as a control. The cuticular profiles of the three species include 48 different hydrocarbons. The cuticular hydrocarbon profiles of the three species of carabids were different, but individuals of Brachinus were chemically more similar to those of Anchomenus than to those of Poecilus; in turn, individuals of Poecilus were more similar to Anchomenus than to Brachinus. We suggest that A. dorsalis is possibly mimicking the cuticular profile of B. sclopeta as an effective antipredator strategy. Brachinus sclopeta may benefit from a reduction of individual predation risk due to an increased number of aggregated preys (dilution effect), while A. dorsalis may increase the benefit both from the dilution effect and from the greater chemical defense of B. sclopeta.

Outdoor post-mortem bite injuries by Tapinoma nigerrimum (Hymenoptera, Formicidae) on a human corpse: Case report

Ants are among the insects that colonize exposed human and animal corpses during the early stage of decomposition. In Calabria, Italy (as well as in other countries), Formicidae have been observed preying on immature stages of Diptera and other insects, as well as causing irregular scalloped areas of superficial skin loss on human corpses and animal carcasses. We present a case of injuries on a human corpse caused by ant feeding. The macroscopic appearance is described and the results of a histochemical investigation of the skin lesions caused by worker ants are reported for the first time. The investigation was carried out on the fresh corpse of a 53-year-old man discovered in a rural area of Cosenza province (Calabria, southern Italy). Numerous irregular areas of superficial skin loss caused by the ant Tapinoma nigerrimum (Nylander 1856) (Hymenoptera, Formicidae) were observed on the body surface, inflicted very early in the post-mortem period. Because the classification of lesions is of crucial importance for forensic investigations, the macroscopic appearance and distribution pattern of the lesions on the corpse are illustrated. The histochemical investigation of the damaged skin explains, for the first time, the mechanism of production of the lesions.

Predator feeding choice on conspicuous and non-conspicuous carabid beetles: first results

Abstract Insects use various types of behaviour, chemical defences, mimetic, aposematic or cryptic appearances as anti-predatory strategies. Among insects, carabid beetles of the genus Brachinus are distasteful prey because they discharge an irritating “cloud” of quinones when threatened. These beetles live in aggregations and adopt warning (conspicuous pattern) colours and chemicals to create a template that is easily learnt by predators. Another carabid beetle, Anchomenus dorsalis, mimics the colours and cuticular profile of Brachinus and is usually found in Brachinus aggregations. In this paper we report results from laboratory observations on feeding choice of the following natural predators - Crocidura leucodon (Insectivora: Soricidae), Ocypus olens (Coleoptera: Staphylinidae) and Podarcis sicula (Reptilia: Lacertidae) - on carabid beetle species. Comparing the number of attacks of predators towards aposematic and non-aposematic prey, there was a statistically significant preference towards non-aposematic prey.