Krzysztof Szpila

An initial study of insect succession and carrion decomposition in various forest habitats of Central Europe

At the end of summer and beginning of fall 2005 insect succession and pig carrion decomposition were studied in pine-oak forest, hornbeam-oak forest, and alder forest in Western Poland (Central Europe). Five stages of decomposition were recognized: fresh stage, bloated stage, active decay stage, advanced decay stage, and remains stage. The highest rate of decomposition was observed in the alder forest and the lowest in the pine-oak forest. A similar composition of carrion entomofauna was found in each forest. Numerous adults of Lucilia caesar, Phormia regina and Calliphora vomitoria (Calliphoridae), Hydrotaea spp. (Muscidae), Stearibia nigriceps and Parapiophila vulgaris (Piophilidae), Necrodes littoralis and Thanatophilus rugosus (Silphidae), Creophilus maxillosus, Omalium rivulare, Oxypoda acuminata and Philonthus spp. (Staphylinidae) as well as larvae of L. caesar, P. regina, C. vomitoria, Fannidae (Diptera) and N. littoralis, C. maxillosus, Philonthus (Coleoptera) were collected. There were no differences between forests in the sequence of insect occurrence on carrion. However, differences between forests in occurrence time and activity period of some taxa were found. Implications of these results for forensic entomology are discussed.

Insect succession and carrion decomposition in selected forests of Central Europe. Part 2: Composition and residency patterns of carrion fauna

The insect fauna of pig carcasses was monitored in different seasons and forests of Western Poland (Central Europe). The composition of carrion fauna and selected features of residency in carrion in adults and larvae of particular taxa were analysed. A total of 131 adult and 36 larval necrophilous taxa were collected. Only 51 adult species and 24 larval taxa were minimally abundant (>or=10 specimens) at least on one carcass. As for the composition of carrion fauna, there were large differences between seasons, but no important differences between forest types. In most species of Diptera, length of the presence period of adults was between 35 and 65% of the sampling interval, while in most species of Coleoptera, it was above 60%. Only in a few species (e.g., Saprinus semistriatus, Necrodes littoralis or Creophilus maxillosus) was the presence period shorter than 35% of the sampling interval. Interestingly, in some adult Coleoptera (e.g., Necrobia violacea) very long presence periods were recorded. In most taxa, the length of the presence period of larvae was between 40 and 65% of the sampling interval. Only Calliphora vomitoria, Phormia regina, Hydrotaea dentipes, N. littoralis and C. maxillosus had shorter presence periods of larvae. As a rule, residency of adults was broken, whereas residency of larvae was unbroken. Moreover, in adults, two distinct residency patterns were observed; with breaks clumped in the final part of the presence period and with breaks evenly distributed inside the presence period. Almost in all taxa, the time of appearance showed the closest relationship to the onset of bloating. The relationship was significant, positive and strong in adults of P. regina, Fannia manicata, Hydrotaea ignava, Stearibia nigriceps, S. semistriatus, N. littoralis and C. maxillosus as well as larvae of P. regina, H. dentipes, H. ignava, S. nigriceps, N. littoralis, Oiceoptoma thoracicum, Thanatophilus sp., C. maxillosus and Philonthus sp. Interestingly, in some forensically significant taxa (e.g., adults of N. violacea or Thanatophilus rugosus), we found no significant relationship between the time of their appearance and the onset of any decompositional process. Implications for the succession-based post-mortem interval (PMI) estimation, determination of the carcass movement and the season of death are discussed.

Insect succession and carrion decomposition in selected forests of Central Europe. Part 1: Pattern and rate of decomposition

Pig carrion decomposition and insect succession were monitored in different seasons and forests of Central Europe. Pattern of decomposition as well as onset, duration and rate of decompositional processes were measured. Pattern of decomposition was the same in almost all cases with putrefaction, active and advanced decay. In the majority of carcasses active decay was driven by larvae of Calliphoridae with a clear seasonal shift in dominant taxa. However, in some spring, alder forest cases active decay was driven by larvae of Necrodes littoralis (Coleoptera: Silphidae). As a rule the mosaic decomposition was observed. In spring a significant delay in onset of all decompositional processes was found. Season significantly affected rate of active decay due to a much higher rate in summer. Decomposition in alder forest proceeded faster than in pine-oak forest and hornbeam-oak forest. Differences between the latter two forests were practically negligible. Implications for forensic entomology are discussed.

Morphology of the first instar of Calliphora vicina , Phormia regina and Lucilia illustris (Diptera, Calliphoridae)

Abstract Scanning electron microscopy documentation of first instar Calliphora vicina Robineau‐Desvoidy, Phormia regina (Meigen) and Lucilia illustris (Meigen) (Diptera: Calliphoridae) is presented for the first time, and the following morphological structures are documented: pseudocephalon; antenna; maxillary palpus; facial mask; labial lobe; thoracic and abdominal spinulation; spiracular field; posterior spiracles, and anal pad. Light microscopy documentation and illustrations are provided for the cephaloskeleton in lateral and ventral views. New diagnostic features are revealed in the configuration of the facial mask, cephaloskeleton and posterior spiracles. The first instar morphology of C. vicina, Ph. regina and L. illustris is discussed in the light of existing knowledge about early instars of blowflies.

Morphology and identification of first instars of the European and Mediterranean blowflies of forensic importance. Part II. Luciliinae.

First instars of Lucilia ampullacea Villeneuve, Lucilia caesar Linnaeus, Lucilia cuprina Weidemann, Lucilia richardsi Collin, Lucilia sericata Meigen and Lucilia silvarum Meigen (Diptera: Calliphoridae) are thoroughly documented with scanning electron microscopy images, light microscopy photographs and line drawings. The following morphological structures are documented: pseudocephalon, antennal complex, maxillary palpus, facial mask, cephaloskeleton, thoracic and abdominal spinulation, spiracular field, and posterior spiracles. New diagnostic features of the cephaloskeleton are presented and the spinulation of the abdominal segments is described. Earlier descriptions are summarized and major discrepancies with the current study are discussed. The present results allow for the clarification, correction and, especially, complementing existing information provided by numerous authors. The first instar larva of L. richardsi is described for the first time and an identification key to the first instars of European species of Lucilia Robineau‐Desvoidy of forensic importance is presented.

Key for the Identification of Third Instars of European Blowflies (Diptera: Calliphoridae) of Forensic Importance

In Europe larvae of blowflies are the main group of insects responsible for decomposition of exposed vertebrate remains, including the human body. This determines their high forensic importance and frequent application for estimation of PMI. The importance of proper identification of insects collected in forensic cases and experiments to the species level is underlined by all manuals of forensic entomology (e.g. Smith 1986; Byrd and Castner 2001; Greenberg and Kunich 2002). Especially difficult is the identification of the larval stages, where breeding to the adult stage or DNA-based methods are recommended. Fortunately, the available knowledge of the morphology of third instars of Calliphoridae is sufficiently good to allow the preparation of a complete identification key for at least all European species of forensic importance. Eleven species are included in the key. Most of them are widespread through Europe (Rognes 2004) and have been frequently reported from both real cases and carrion experiments, and the necessity of their inclusion into the key cannot be questioned. There are: Calliphora vicina, C. vomitoria, Chrysomya albiceps, Phormia regina, Protophormia terraenovae, Lucilia caesar, L. illustris, L. sericata. The author has also decided to add three additional species to the key: Cynomya mortuorum, Chrysomya megacephala, and Lucilia ampullacea. Recently, the larvae of Cynomya mortuorum were recorded from human corpses at least twice (Staerkeby 2001; Benecke 2002). Smith (1986) points out this species as rather a late newcomer in comparison to other blowflies, but recent research on succession shows that in spring conditions Cynomya mortuorum may be among the first colonizers of pig carrion (Szpila et al. 2008).

A new dipteran forensic indicator in buried bodies.

The first breeding records of miltogrammine fleshflies in buried vertebrate carrion are presented. First instars of Eumacronychia persolla Reinhard (Nearctic) (Diptera: Sarcophagidae) and Phylloteles pictipennis Loew (Palaearctic) (Diptera: Sarcophagidae) are able to penetrate dry, loose soil and reach deeply buried animal remains, an ability which distinguishes is unique to necrophagous Calyptratae. Their broad geographical distribution, fast location and colonization of carrion, complete development on buried food resources and easy identification make these species useful forensic indicators in buried bodies in dry habitats.

Species identification of Middle Eastern blowflies (Diptera: Calliphoridae) of forensic importance

The lack of reliable tools for species identification of necrophagous blowflies of the Middle East is a serious obstacle to the development of forensic entomology in the majority of countries of this region. Adding to the complexity of diagnosing the regional fauna is that species representing three different zoogeographical elements exist in sympatry. In response to this situation, a high-quality key to the adults of all species of forensically relevant blowflies of the Middle East has been prepared. Thanks to the modern technique of image-stack stereomicroscopy and high-quality entomological materials, this new key can be easily applied by investigators inexperienced in the taxonomy of blowflies. The major technical problems relating to the species identification of necrophagous blowflies of the Middle East are also discussed.

The first instar larva of Apodacra pulchra (Diptera: Sarcophagidae, Miltogramminae)

The morphology of the first instar larva of the miltogrammine flesh fly Apodacra pulchra Egger, 1861 is described using SEM and light microscopy. The larva is shown to possess a strongly modified pseudocephalon with comb-like lateral processes, a large ventral organ, and a transversely enlarged, slit-like (or ⊥-shaped) functional mouth opening. The thoracic cuticle is forming longitudinal ridges, and the abdominal segments have a single long lateral sensory sensilla on each side. Morphology is discussed in context of the remaining Oestroidea in general and of the subfamily Miltogramminae in particular.

A large-scale molecular phylogeny of flesh flies (Diptera: Sarcophagidae)

The available data for Sarcophagidae in GenBank were analysed in order to reconstruct the most comprehensive phylogeny to date. GenBank was explored for nine markers that are commonly used in various molecular and phylogenetic studies of flesh flies. We obtained data for 187 species and constructed an aligned dataset with 9241 characters. However, the matrix suffered from 74% missing data due to a low number of sequences for some markers and in most of the cases only short fragments of the analysed genes were available. The reconstructed tree was taxonomically biased towards the subfamilies Paramacronychiinae (12% of the described species) and Sarcophaginae (8.6% of the described species) and specifically the genus Sarcophaga. The third subfamily Miltogramminae was represented by only 0.7% of described species. Moreover, about half of the included species were of forensic importance, while the percentage of such species in the entire family was estimated at 7%. Many nodes had very low support, so in order to increase the support and thereby identify a ‘core topology’, we pruned ‘rogue’ taxa and applied different substitution models. Both strategies improved support considerably, although some nodes still were left unresolved. An analysis of the distribution of bootstrap values across chronograms showed that the weakest phylogenetic signal is restricted to that part of the tree which coincides with the onset of rapid radiations mainly within the genus Sarcophaga. Our study is concordant with phylogenies obtained by other authors, with the most noteworthy exception being the subfamily Paramacronychiinae emerging as paraphyletic with regard to the Miltogramminae, which is in strong conflict with morphological evidence. We discuss the new findings in the light of traditional taxonomical classifications of Sarcophagidae and recent molecular studies.