Micromorfología comparada de estadios inmaduros de Calliphoridae (InsectaDiptera) de interés forense

Abstract

Abstract: Forensic Entomology is a very important support for Forensic Sciences, not only to estimate the postmortem interval (IPM) (Legal Entomology), but also in anthropic environments (Urban Entomology) as well as stored products (Entomology of Stored Products). Diptera, and especially the Calliphoridae family, are the main members of the sarcosaprophagous fauna since many species developed their immature stages in this type of ecosystem (necrophagous species). The morphological knowledge allowing the unequivocal differentiation of the species of Calliphoridae is scarce for immature specimens. The main cause is that for a correct identification of these instars detailed micromorphological studies of all the characters of taxonomic interest are needed, mainly studies combining optical microscopy (MO) and scanning electron microscopy (SEM). In this respect, it should be remembered that, collection procedures of entomological evidence as recommended by the European Association of Forensic Entomology (EAFE) do not fit the usual protocols for scanning electron microscopy (SEM). Therefore, in this thesis we have tried to evaluate different protocols of scanning electron microscopy to establish which is the most appropriate to study the immature stages of sarcosaprophagous Diptera (egg, larvae I, II and III and puparium) and to apply them to the micromorphological description of all immature stages of five species of calliphorids, (Calliphora vicina Robineau-Desvoidy, 1830, Calliphora vomitoria Linnaeus, 1758, Chrysomya albiceps Wiedemann, 1819, Protophormia terraenovae Robineau-Desvoidy, 1830, Lucilia sericata Meigen, 1826), establishing which features allow to correlate morphologically the stages in each species as well as their taxonomic utility to distinguish species each other within subfamilies Calliphorinae, Chrysomynae and Lucilinae. Ethanol fixation has been satisfactory in the immature specimens studied; so, the recommendations of EAFE are compatible with the use of MEB in this material although, complex aldehyde fixatives are confirmed as the most suitable for this type of specimens and microscopy technique. Then this latter is recommended to be applied when the forensic entomological evidence could arrive alive to the laboratory to be treated. The morphological study of the five species of Calliphoridae studied has shown, in the light of the results obtained from the observation to the MEB, that there is enough variability regarding different features to be able to distinguish species in each of the immature stages. However, the lack of bibliographical data concerning other species with this type of microscopy, except for the eggs and larvae of first stage, does not allow to compare appropriately our species with the others. In fact, the descriptions provided of the larvae of second and third stages, as well as the puparia, of all species studied constitute the first complete descriptions based on mixed techniques of MO and MEB. However, using the data available in the scientific literature, it has been possible to verify the taxonomical potential of different features, such as the pattern of spiny bands, the morphology of the spines, the ventral organ and the lobule, the cirrus, the anterior and posterior spiracles, the distribution of posterior papillae and the anal protuberance, although they have not been able to be used homogeneously to identify the other species of european Calliphoridae due to the lack of previous descriptions.