Forensic entomology: a new hypothesis for the chronological succession pattern of necrophagous insect on human corpses

Forensic entomology can help to estimate the time elapsed since death, by studying the necrophagous species collected on a cadaver and its surroundings. The determination of the so- called post mortem interval (PMI or period of first oviposition) is based on the development time of necrophagous dipterans and on the chronological pattern of insects’ succession on the corpse throughout the decaying process. In the present study, authors investigated this succession by the analysis of the database of the Department of Forensic Entomology of the French Gendarmerie over 12 years (1992–2003) in order to propose a new approach and a new hypothsesis of the dynamic of necrophagous-insects’ populations present on a human cadaver over time. For all treated cases, the presence/absence and the oldest development stage of the species were recorded. Data were analyzed by statistical and Wagner parsimony methods. The statistic results allowed the association of groups of species with typical developmental stages. The Wagner parsimony analysis showed that the dynamic of the necrophagous insect population present on a cadaver could be characterised by specific species. Together, they allowed establishing hypotheses of succession of necrophagous insects on human cadavers over time that could be usefull in the PMI estimation.     

Symbiotic bacteria in the relationship between Anaphes nitens (Hymenoptera: Mymaridae) and Gonipterus platensis (Coleoptera: Curculionidae)

The egg parasitoid Anaphes nitens (Hymenoptera: Mymaridae) parasitizes the Eucalyptus snout-beetle Gonipterus platensis (Coleoptera: Curculionidae), one of the main defoliating beetles of Eucalyptus. Outbreaks of this pest are being recorded in areas with low parasitism rates by A. nitens. Endosymbiont bacteria can affect the reproductive characteristics of host insects increasing or decreasing the parasitism rate. The objectives of this study were to identify the presence, phylogeny and transmission modes of endosymbiont bacteria in A. nitens and G. platensis. Six populations of A. nitens and one of G. platensis were evaluated. Genomic DNA from these populations was extracted and nine genera of cell endosymbionts were searched by PCR. Three species of the Enterobacteriaceae family, Erwinia amylovora, Serratia grimesii, Yersinia massiliensis and the cell endosymbiont Rickettsia belli were identified in all A. nitens populations. Only Serratia grimesii was found in G. platensis. The presence of E. amylovora, Y. massiliensis and R. belli in the F1 and F2 generations indicates vertical transmission in A. nitens, while S. grimesii is vertically transmitted in G. platensis.     

Linnaeus's butterflies (Lepidoptera: Papilionoidea and Hesperioidea)

The names of all the species of butterflies described by Linnaeus under "Papilio" are researched. Of the 305 names treated, 243 (c. 80%) are currently valid as specific (241) or subspecific (2), 29 are junior synonyms, 14 are invalid (one of these applying to a fake), and for 13 the identity is unknown or uncertain. Six species of moths misidentified by Linnaeus as butterflies are cited in the study, but details are not included. One hundred and fifty-two lectotypes have been designated, representing about 56% of the sum of the valid names and junior synonyms. Of these, 99 were selected from specimens in the Linnean Society of London, 52 from Queen Ludovica Ulrica's collection, Uppsala, and one lectotype is a Petiver specimen from the collection of Sir Hans Sloane. Linnaeus described at least five species, possibly eight, from the literature alone. All Linnaean material examined is documented, as are 'subsequent' specimens that are associated with Linnaean material. Synonymy and homonymy are discussed and presented, as are the identities of type localities. Care has been taken to achieve a practical balance between Linnaean and current species identities. Linnaean material studied included specimens from The Linnean Society of London, Museum Ludovicae Ulricae (Uppsala University), the Clerck and De Geer collections in the Naturhistoriska Riksmuseet, Stockholm, and the collection of James Petiver, now part of the collection of Sir Hans Sloane housed in The Natural History Museum, London.     

Lens cell-to-cell channel protein: I. Self-assembly into liposomes and permeability regulation by calmodulin

Summary Lens fibers are coupled by communicating junctions which contain a 28-kDalton protein (MIP26) believed to be the main component of the cell-to-cell channel. To study the permeability properties and regulation of these channels, anin vitro system has been developed in which MIP26 isolated from calf lens is incorporated into liposomes and the resulting channels are studied spectrophotometrically by a swelling assay. Liposome vesicles were prepared using a sonication/resuspension method. Incorporation efficiency was monitored by freeze-fracture. Vesicles were resuspended in 6% Dextran T-10. Assay buffer was identical, except for isotonic substitution of sucrose for T-10. MIP26-incorporated (but not control) vesicles swell under isotonic conditions indicating sucrose entry (via channels) followed by water to maintain osmotic balance. In the absence of calmodulin, calcium ion has no effect on channel permeability. On the contrary, vesicles prepared with equimolar amounts of MIP26 and CaM do not swell in the presence of calcium ion, indicating that the channels can be closed. Addition of EGTA to these vesicles reinitiates swelling—evidence that the channel gating mechanism is reversible. Magnesium ion has no effect on either type of vesicle.     

Characterization of the complete mitochondrial genome of Hydrotaea spinigera (Diptera: Muscidae) with phylogenetic implications

Hydrotaea spinigera Stein is a muscid species with high forensic importance. To further supplement the genome-level features of related species, the complete mitochondrial genome of H. spinigera is amplified, sequenced, annotated, analyzed, and compared with 13 other species of the family Muscidae. This mitogenome is 15,517?bp in length, with a standard set of 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a typical non-coding control region. The gene organization, base composition, and secondary structures of tRNA genes of this mitogenome are similar to other dipteran species. Phylogenetic analyses based on all the mitochondrial PCGs and rRNA genes for 14 muscid and one outgroup taxa are performed using Bayesian inference (BI) and maximum likelihood (ML) analysis. The inferred trees indicate that the Muscidae, the subfamily Muscinae, and the tribes Azeliini and Reinwardtiini are monophyletic, whereas the monophyly of the subfamily Azeliinae and the tribe Muscini is not supported.     

The species of Papilionidae and Pieridae (Lepidoptera) described by Cramer and Stoll and their putative type material in the Natural History Museum in London

A history is presented of specimens of Papilionidae and Pieridae in the Natural History Museum, London that are thought to include types of species described by Cramer and Stoll in ' De Uitlandsche Kapellen '. Background details on the publication and associated persons are also provided. The authenticity of the specimens is discussed together with a list of all the material available. Details of homonymy and synonymy are presented as discussed. Lectotypes are designated for Papilio alcmeone Cramer, 1777 , and Papilio antonoe Cramer, 1777 .  © 2005 The Natural History Museum, London, Zoological Journal of the Linnean Society , 2005, 145 , 283–337.     

Seasonal patterns of nitrogen fixation in termites

1. Termite nitrogenase activity was highest in autumn and spring (≈ 3 μg N₂ fixed termite fresh mass (g)^–1 day^–1) and lowest in winter and summer (≈ 0·8 μg N₂ fixed termite fresh mass (g)^–1 day^–1).
2. The nitrogenase activity of worker termites was significantly higher than all other castes (1·58 ± 0·27 μg N₂ fixed termite fresh mass (g)^–1 day^–1).
3. Worker termites constituted the largest proportion of all the castes throughout the study period (≈ 90%).
4. The localized input of fixed nitrogen by termites may reach 15·3 mg N log^–1 day^–1 and 5·6 g N log^–1 year^–1.     

Eusocial bee male aggregations: spatially and temporally separated but genetically homogenous

Male insects mostly aggregate near sites where sexually reproductive virgin females are found and where mating occur. This reproductive strategy is quite common in Hymenoptera and appears to decrease the chances of inbreeding. In Hymenoptera, inbred mating frequently result in sterile diploid males. Production of diploid males may reach high proportions in small bee populations, and it usually lead to population extinction within a small number of generations. Aggregation of males during a short period of time allow the mixing of local genes. In this paper, we analyzed male aggregations of Tetragonisca angustula (Latreille) (Hymenoptera: Apidae), a eusocial stingless bee, using microsatellite molecular markers. We used population genetic statistics for haplodiploid organisms to address genetic structuring among male aggregations. Our findings indicate that, in general, male aggregations of T. angustula occurring over short time scales and in close proximity are genetically homogeneous as if a single aggregation. We conclude that T. angustula males randomly disperse within a population looking for mating chances rather than settle on a distinct male aggregation. This behavior seems to contribute to the reduction of inbreeding in this species.     

Heat accumulation and development rate of massed maggots of the sheep blowfly,Lucilia cuprina (Diptera: Calliphoridae)

Blowfly larvae aggregate on exposed carcasses and corpses and pass through three instars before wandering from the carcass and pupating. The developmental landmarks in this process can be used by forensic entomologists to estimate the time since the insects colonised the carcass, which sets a minimum post mortem interval. Large aggregations of feeding larvae generate a microclimate with temperatures up to 15 °C above ambient conditions, which may accelerate larval development and affect forensic estimates of post-mortem intervals. This study investigated the effects of heat accumulated by maggot masses of Lucilia cuprina at aggregations of 20, 50 and 100 larvae, each at incubation temperatures of 18 °C, 24 °C and 30 °C, using body length and life stage as developmental indicators. Aggregation temperatures reached up to 18.7 °C above ambient temperature, with significant effects of both size and temperature of the aggregation on the development time of its larvae. Survivorship was highest for all life stages at 24 °C, which is near the developmental optimum of L. cuprina. The results of this study provide a broadly applicable method of quantifying heat accumulation by aggregations of a wide range of species of forensic importance, and the results obtained from such studies will demonstrate that ambient temperature cannot be considered the only source of heat that blowfly larvae experience when they develop on a carcass. Neglect of temperatures within larval aggregations will result in an overestimation of post-mortem intervals and thus have far-reaching medicolegal consequences.