975 resultados para Saw-flies.
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Biodiversity is unequally spread throughout terrestrial ecosystems. The highest species richness of animals and plants is encountered around the Equator, and naturalists observe a decrease in the number of creatures with increasing latitude. Some animal groups, however, display an anomalous species richness pattern, but these are exceptions to the general rule. Crane flies (Diptera, Tipuloidea) are small to large sized, non-biting nematoceran insects, being mainly associated with moist environments. The species richness of crane flies is highest in the tropics, but these insects are species rich and abundant in all biogeographic realms, boreal and arctic biomes included. The phylogeny and systematics of crane flies are still at an early stage and somewhat controversial. New species are constantly discovered even from temperate Europe, faunistically the best known continent. Crane flies have been rather neglected group of insects in Finland. The history of Finnish crane fly taxonomy and faunistics started in 1907, the year when Carl Lundström published his two first articles on tipuloids. Within roughly 100 years there have been only a handful of entomologists studying the Finnish fauna, and the species richness and natural history of these flies have remained poorly understood and mapped. The aim of this thesis is to clarify the taxonomy of Finnish crane flies, present an updated and annotated list of species and seek patterns in regional species richness and assemblage composition. Tipula stackelbergi Alexander has been revised (I). This species was elevated to a species rank from a subspecific rank under T. pruinosa Wiedemann and T. stackelbergi was also deleted from the list of European crane flies. Two new synonyms were found: T. subpruinosa Mannheims is a junior synonym of T. freyana Lackschewitz and T. usuriensis Alexander is a junior synonym of T. pruinosa. A new species Tipula recondita Pilipenko & Salmela has been described (II). Both morphology and COI (mtDNA) sequences were used in the assessment of the status of the species. The new species is highly disjunct, known from Finland and Russian Far East. A list of Finnish crane flies was presented, including the presence of species in the Finnish biogeographical provinces (III). A total of twenty-four species were formally reported for the first time from Finland and twenty-two previously reported species were deleted from the list. A short historical review on the studies of Finnish crane flies has been provided. The current list of Finnish species consists of 338 crane flies (IV, Appendix I). Species richness of all species and saproxylic/fungivorous species is negatively correlated with latitude, but mire-dwelling species show a reversed species richness gradient (i.e. an increase in the number of species toward north). Provincial assemblages displayed a strong latitudinal gradient and faunistic distance increased with increasing geographical distance apart of the provinces. Nearly half (48 %) of the Finnish crane flies are Trans-Palaearctic, roughly one-third (34 %) are West Palaearctic and only 16 and 2 % are Holarctic and Fennoscandian, respectively. Due to the legacy of Pleistocene glaciations, endemic Fennoscandian species are problematic and it is thus concluded that there are probably no true endemic crane flies in this region. Finally, there are probably species living within Finnish borders that have hitherto remained unnoticed. Based on subjective assessment, the number of “true” (i.e. recorded + unknown species) species count of Finnish crane flies is at minimum 350.
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Mermithid nematodes (Nematoda: Mermithidae) parasitize larval, pupal and adult black flies (Diptera: Simuliidae), oftentimes resulting in partial or complete host feminization. This study was designed to characterize parasite-host seasonal variation and to estabUsh the developmental life stage at which feminization is initiated. Data indicate that the total adult population of black flies collected from Algonquin Provincial Park throughout the spring of 2004 was comprised of 31.8% female, 67.8% male and 0.4% intersex individuals. Of the total population, 0.6% was infected by mermithid nematodes (69.0% female, 3.5% male and 27.6% intersex). Seasonal infection trends established over a 12-month period revealed that black flies with different life histories host the same mermithid subfamilies, while black flies with similar life histories host mermithids from different subfamilies. If a simuliid species simultaneously hosts two mermithid species, these parasites are from different subfamilies. Molecular mermithid identification revealed two mermithid subfamilies, Me.somermithinae and Gastromermithinae, present in the simuliid hosts. Mermithid colour variation was not found to be a reliable species indicator. The developmental stage at which feminization is initiated was determined by examining gonad morphology and meiotic chromosomal condition. Results indicate that mermithid-infected black flies exhibit feminization prior to larval histoblast formation. Larvae can be morphologically male (testes present) or female (ovaries present), with morphological males exhibiting either male (achiasmate) or female (chiasmate) meiotic chromosomes; morphological females were only genetically female. Additionally, mermithid infection inhibits simuliid gonad development.
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The sequential banding patterns of the larval salivary gland polytene chromosomes of seven species of Inseliellum (Diptera: Simuliidae) were mapped. This was completed through the comparison with the standard maps of an eighth species of Inseliellum, Simulium cataractarum. During chromosomal analysis, both fixed and floating inversions were identified. A floating inversion (IIL-l ex,2ex) revealed a cytotype within Simulium exasperans that is distributed between two islands, Moorea and Tahiti. Inversion data revealed three shared fixed inversions that could be used as phylogenetic characters. In addition, the placement of a chromosomal landmark (the nucleolar organizer, or NO) was used as a phylogenetic character. The result of a cytophylogenetic (transformational) analysis showed two groups: the NO-IL group, and the NO-IS group. A combined phylogeny was created using the published morphological data and the cytological data of the eight species. The combined tree did not differ from the morphological data only tree. Possible routes of dispersal are hypothesized using geological, chromosomal, and phylogenetic data. These data showed a general pattern of dispersal and colonization from older islands to younger islands, with one possible instance of dispersal from younger to older islands. It is postulated that inter-island speciation has allowed this dispersal and colonization, but intra-island speciation has created the diversity seen in Inseliellum.
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Although much research has been conducted on blood-meal acquisition in adult female black flies (Diptera: Simuliidae), the same cannot be said for sugarmeals. Both sexes feed on sugar which provides energy for flight and it has been commonly held that nectar is the major carbohydrate source. This thesis addresses the question of whether a non-floral carbohydrate source, specifically homopteran honeydew, is ingested by male and female black flies. Black flies reared in the laboratory have been observed to readily ingest freshly excreted and older (dry) honeydew when presented with honeydew coated tamarack branches. Field work was conducted in Algonquin Park, Ontario in the spring and summer of 1993. Three separate studies were designed to test whether homopteran honeydew is an important carbohydrate source for black flies and whether flies from different habitats utilize different sugar sources. The sugars melezitose and / or stachyose are known to occur in a variety of homopteran honeydews and therefore were used as indicators of honeydew feeding by black flies. In the first study, black flies were collected with insect nets from a stand of Larix larcina heavily infested with honeydew - producing homopterans (Adelges lariciatus). Six black fly species were captured: Simulium venustum, S. rostra tum, S. vittatum, Stegopterna mutata, S. aureum and S. quebecense. Samples of honeydew and individual black flies were tested using thin layer chromatography (T. L. C.) with fructose, glucose, sucrose, turanose, melezitose, raffinose and stachyose as standards. All sugars except turanose and melezitose were found in the adelgid honeydew samples. Since the sugar melezitose was absent from ~ honeydew samples, stachyose was used to indicate that black flies were feeding from this particular honeydew source. Of the 201 black flies tested, 194 contained sugars which occurred in 16 combinations. Stachyose combinations excluding melezitose, present in 45.9 % of flies, were used to indicate that black flies had been feeding on the adelgid honeydew. In the second study, black flies were collected in the morning and evening on 8 collection dates, using a vehicle mounted insect net. The crops and midguts of 10 male and 10 female Simulium venustum were dissected on each sample date. In total the gut contents of 320 individual flies were analysed by T. L. C. The sugars identified from these flies were present in the following proportions: fructose (100.0%), glucose (100.0%), sucrose/turanose (50.4%), melezitose (30.3%), raffinose (18.8%) and stachyose (8.7%). These sugars occurred in fourteen different combinations. It is argued that the presence of melezitose and / or stachyose indicates that black flies had fed on homopteran honeydew. Significantly more female flies (40.0%) than male flies (27.5%) had fed on honeydew. In the third study, adult black flies were sampled by sweep netting vegetation in four habitats in the morning and evening on 8 collection dates. The habitats are as follows: (1) Davies Bog, (2) Abandoned Air Field (dominated by blueberries, Vaccinium spp.), (3) Deciduous Habitat and (4) Coniferous Habitat. Sugars in the crops and midguts of female flies were tested by T. L. C. and, for S. venustum, it was found that significantly fewer flies (18.8%) from the Air Field contained honeydew than from the other three sites (Davies Bog, 34.4%; Deciduous Habitat, 36.2%; Coniferous Habitat, 25.0%). Of the 1287 black flies tested individually by T. L. C. 441 (34.3%) contained melezitose and / or stachyose sugars indicating that this proportion of the population were feeding from Homopteran honeydew. It is therefore clear that floral (nectar) sugars are not the only source of carbohydrates available to black flies.
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The sugar-feeding ecology of dipteran vectors has recently been targeted because it presents opportunities to inoculate common food sources for these dipterans with entomopathogenic bacteria as a means of controlling the population of host-seeking adult dipteran vectors. Whereas this approach to vector control holds some promise, differences in the nutrient composition and concentration in sugary food sources can influence the food selection pattern of dipteran vectors and potentially confound the outcomes of field trials on the efficacy of entomopathogenic bacteria as vector control agents. Further, nutrient components of bacteria-inoculated artificial diets may present unintended effects of extending the survivorship or fecundity of the target population and potentially render the whole approach counterproductive. The present study investigated the diet-specific factors that influence the foraging decisions of female Simulium venustum/verecundum (Diptera: Simuliidae) and female Anopheles stephensi (Diptera: Culicidae) on artificial nectar and honeydew. Paired choice experiments showed that the black flies forage more frequently from high calorie diets, which contained melezitose, or those diets that contained amino acids, compared to low calorie melezitose-free diets or amino acid-free diets. The mosquitoes however displayed a more random diet selection pattern. The effects of sugary diets on certain life-history traits considered to be important to the ecological fitness of the black flies and mosquitoes were also investigated. Sugary diets had no significant effect on the survivorship and fecundity of the black flies, but they influenced the resistance of Leucocytozoon-infected flies to the parasite. Amino acid-containing diets appeared to extend the survival of mosquitoes, and also allowed them to take more vertebrate blood when they blood fed.
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A vignette of J. McDonagh's Saw and Plaining Mills, Welland Canal, Thorold.
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UANL
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La saga Saw est une franchise qui a marqué le cinéma d’horreur des années 2000. Le présent mémoire tâchera d’en faire une étude détaillée et rigoureuse en utilisant la notion de jeu. En élaborant tout d’abord un survol du cinéma d’horreur contemporain et en observant la réception critique de la saga à travers l’étude de différents articles, ce travail tentera en majeure partie d’analyser la franchise Saw en rapport avec l’approche ludique du cinéma en général et celle adoptée par Bernard Perron. Cette étude, qui s’élaborera tant au niveau diégétique que spectatoriel, aura pour but de montrer l’importance de la place qu’occupe la notion de jeu dans cette série de films.
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Winnie, la bruja viaja siempre en su escoba y vuela por el cielo vacío, donde no hay semáforos, ni atascos de tráfico, pero de repente empieza a chocar con un helicóptero, con una avioneta, con edificios altos. Así que, utiliza su varita mágica para transformar su escoba en todo tipo de extrañas y maravillosa cosas. Y ahí es donde comienzan sus problemas.
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Un relato tradicional de origen nigeriano, que encierra una fábula sobre el sol y el zumbido de las moscas.
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All organisms face attack from many natural enemies and all in turn have some means of defence. Can resistance evolve, and if it can, why doesn't it? Recent work on fruit flies and their parasitic wasps has shed light on these questions
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Much is made of the viscerally disturbing qualities embedded in The Texas Chain Saw Massacre - human bodies are traumatised, mutilated and distorted – and the way these are matched by close and often intense access to the performers involved. Graphic violence focused on the body specifically indicates the film as a key contemporary horror text. Yet, for all this closeness to the performers, it soon becomes clear in undertaking close-analysis of the film that access to them is equally characterised by extreme distance, both spatially and cognitively. The issue of distance is particularly striking, not least because of its ramifications on engagement, which throws up various aesthetic and methodological questions concerning performers’ expressive authenticity. This article considers the lack of access to performance in The Texas Chain Saw Massacre, paying particular attention to how this fits in with contemporaneous presentations of performance more generally, as seen in films such as Junior Bonner (Sam Peckinpah, 1972). As part of this investigation I consider the affect of such a severe disruption to access on engagement with, and discussion of, performance. At the heart of this investigation lie methodological considerations of the place of performance analysis in the post-studio period. How can we perceive anything of a character’s interior life, and therefore engage with performers who we fundamentally lack access to? Does such an apparently significant difference in the way performers and their embodiment is treated mean that they can even be thought of as delivering a performance?