55 research outputs found

    The Species Richness of Lepidoptera in a Fragmented Landscape: A Supplement to the Checklist of Moths of Butler County, Ohio

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    Land conversion for agriculture or urban expansion has fragmented the midwestern landscape and isolated native biotas in remnant habitat patches. Identification of priority renmants to be targeted for conservation, however, requires an understanding of the species diversity and distributions in such fragmented landscapes. During a 3-year inventory, we estimated the species richness of Lepidoptera in forests and old fields within an agricultural region of southwest Ohio, Butler County. A combination of casual collecting (butterflies) and a systematic field study (moths) were used to sample lepidopteran species at several sites from 1998-2000. Our inventory added 207 new species to the checklist of the Lepidoptera of Butler County, bringing the total described species richness of the region to 599 species (including Peoria tetradella (Pyralidae), a state record). The species accumulation curve produced from our 1999 moth inventory did not reach saturation, suggesting that additional species remain to be recorded. These results indicate that even highly modified landscapes can support a substantial species diversity of Lepidoptera if there are sufficient areas of native habitat. Since short-term insect inventories tend to be biased toward common, well-known species, rapid diversity assessments may miss important elements of conservation interest. Checklists should remain an important data source for species occurrences and biogeography. Without a well-established knowledge of species geography, critical areas of conservation interest may be overlooked or left unprotected

    The Species Richness of Lepidoptera in a Fragmented Landscape: A Supplement to the Checklist of Moths of Butler County, Ohio

    Get PDF
    Land conversion for agriculture or urban expansion has fragmented the midwestern landscape and isolated native biotas in remnant habitat patches. Identification of priority renmants to be targeted for conservation, however, requires an understanding of the species diversity and distributions in such fragmented landscapes. During a 3-year inventory, we estimated the species richness of Lepidoptera in forests and old fields within an agricultural region of southwest Ohio, Butler County. A combination of casual collecting (butterflies) and a systematic field study (moths) were used to sample lepidopteran species at several sites from 1998-2000. Our inventory added 207 new species to the checklist of the Lepidoptera of Butler County, bringing the total described species richness of the region to 599 species (including Peoria tetradella (Pyralidae), a state record). The species accumulation curve produced from our 1999 moth inventory did not reach saturation, suggesting that additional species remain to be recorded. These results indicate that even highly modified landscapes can support a substantial species diversity of Lepidoptera if there are sufficient areas of native habitat. Since short-term insect inventories tend to be biased toward common, well-known species, rapid diversity assessments may miss important elements of conservation interest. Checklists should remain an important data source for species occurrences and biogeography. Without a well-established knowledge of species geography, critical areas of conservation interest may be overlooked or left unprotected

    Insect herbivory in an experimental agroecosystem: the relative importance of habitat area, fragmentation, and the matrix

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    Habitat area, fragmentation, and the surrounding matrix influence levels of herbivory in various ecosystems, but the relative importance of these effects has rarely been assessed. We compared levels of herbivory and densities of dominant arthropod herbivores (the hemipteran insects Agallia constricta, Empoasca fabae, Therioaphis trifolii, Lygus lineolaris and Halticus bractatus) among experimental plots that varied in the area and fragmentation of clover habitat and the composition of the matrix (bare ground or grass) surrounding clover habitat. To assess levels of herbivory, we compared clover biomass within herbivore exclosures to the biomass accessible to herbivores. The area and fragmentation of clover habitat, as well as matrix composition, significantly influenced the collective densities of herbivores, although each species exhibited unique responses to habitat structure. Herbivory was strongest in plots with large (64 m 2 ) as compared to small (16 m 2 ) amounts of clover habitat. The difference in clover biomass between the inside and outside of exclosures increased significantly with increasing density of Empoasca fabae but was unrelated to the densities of the other herbivores, suggesting that Empoasca fabae was an exceptionally important herbivore in this system. This study supports the view that herbivore densities and herbivory generally increase with increasing area of plant monocultures, but emphasizes that levels of herbivory may be driven primarily by one or a few key herbivore species

    Effects of Landscape Structure on Movement Patterns of the Flightless Bush Cricket Pholidoptera griseoaptera

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    Because the viability of a population may depend on whether individuals can disperse, it is important for conservation planning to understand how landscape structure affects movement behavior. Some species occur in a wide range of landscapes differing greatly in structure, and the question arises of whether these species are particularly versatile in their dispersal or whether they are composed of genetically distinct populations adapted to contrasting landscapes. We performed a capture-mark-resight experiment to study movement patterns of the flightless bush cricket Pholidoptera griseoaptera (De Geer 1773) in two contrasting agricultural landscapes in France and Switzerland. The mean daily movement of P. griseoaptera was significantly higher in the landscape with patchily distributed habitat (Switzerland) than in the landscape with greater habitat connectivity (France). Net displacement rate did not differ between the two landscapes, which we attributed to the presence of more linear elements in the connected landscape, resulting in a more directed pattern of movement by P. griseoaptera. Significant differences in the movement patterns between landscapes with contrasting structure suggest important effects of landscape structure on movement and dispersal success. The possibility of varying dispersal ability within the same species needs to be studied in more detail because this may provide important information for sustainable landscape planning aimed at maintaining viable metapopulations, especially in formerly well-connected landscape

    Cryo Electron Tomography of Native HIV-1 Budding Sites

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    The structure of immature and mature HIV-1 particles has been analyzed in detail by cryo electron microscopy, while no such studies have been reported for cellular HIV-1 budding sites. Here, we established a system for studying HIV-1 virus-like particle assembly and release by cryo electron tomography of intact human cells. The lattice of the structural Gag protein in budding sites was indistinguishable from that of the released immature virion, suggesting that its organization is determined at the assembly site without major subsequent rearrangements. Besides the immature lattice, a previously not described Gag lattice was detected in some budding sites and released particles; this lattice was found at high frequencies in a subset of infected T-cells. It displays the same hexagonal symmetry and spacing in the MA-CA layer as the immature lattice, but lacks density corresponding to NC-RNA-p6. Buds and released particles carrying this lattice consistently lacked the viral ribonucleoprotein complex, suggesting that they correspond to aberrant products due to premature proteolytic activation. We hypothesize that cellular and/or viral factors normally control the onset of proteolytic maturation during assembly and release, and that this control has been lost in a subset of infected T-cells leading to formation of aberrant particles

    Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

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    Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

    Landscape and Local Controls of Insect Biodiversity in Conservation Grasslands: Implications for the Conservation of Ecosystem Service Providers in Agricultural Environments

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    The conservation of biodiversity in intensively managed agricultural landscapes depends on the amount and spatial arrangement of cultivated and natural lands. Conservation incentives that create semi-natural grasslands may increase the biodiversity of beneficial insects and their associated ecosystem services, such as pollination and the regulation of insect pests, but the effectiveness of these incentives for insect conservation are poorly known, especially in North America. We studied the variation in species richness, composition, and functional-group abundances of bees and predatory beetles in conservation grasslands surrounded by intensively managed agriculture in Southwest Ohio, USA. Characteristics of grassland patches and surrounding land-cover types were used to predict insect species richness, composition, and functional-group abundance using linear models and multivariate ordinations. Bee species richness was positively influenced by forb cover and beetle richness was positively related to grass cover; both taxa had greater richness in grasslands surrounded by larger amounts of semi-natural land cover. Functional groups of bees and predatory beetles defined by body size and sociality varied in their abundance according to differences in plant composition of grassland patches, as well as the surrounding land-cover diversity. Intensive agriculture in the surrounding landscape acted as a filter to both bee and beetle species composition in conservation grasslands. Our results support the need for management incentives to consider landscape-level processes in the conservation of biodiversity and ecosystem services
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