1,720,961 research outputs found
Trophic Interactions between Generalist Predators and the Two Spotted Spide Mite, <i>Tetranychus urticae</i> in, Strawberry
No full textThe two spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a major cause of pest damage worldwide. Its host range includes among many the strawberry crop, a high value crop in Denmark as well as in many other temperate and subtropical regions. Chemical control of T. urticae have been challenged by the polyphagous nature of T. urticae and its ability to reproduce exceedingly fast under optimal conditions. T. urticae have shown to be able to develop resistance towards chemical pesticides. Pest control by chemical means also have the unfortunate side-effect of reducing populations of naturally occurring enemies.The potential and ability of phytoseiid predatory mites to control T. urticae have long been recognized. Less known is the potential of insect predators to control this pest and especially the naturally occurring generalist predators. Knowledge of the natural occurrence and diversity of predatory insects and predatory mites in Danish strawberry fields and surrounding vegetation is lacking, as is the knowledge of the potential of generalist insect predators to control T. urticae.The overall objective of this PhD thesis was to investigate the trophic interactions between natural enemies, in particular generalist predators and the two spotted spider mite, T. urticae, in strawberry. This was done by investigating interactions of T. urticae and its natural enemies as influenced by cropping practice and the surrounding vegetation (Manuscript I) as well as more specifically defined predator-prey interactions (Manuscript II and III) and interactions occurring between groups of natural enemies (Manuscript IV).Cropping practice influenced the density of T. urticae profoundly, with a ten times higher abundance found in conventional compared to organic strawberry fields (Manuscript I). Cropping practice also influenced the abundance, distribution and species richness of the arthropod natural enemies. The ratio of predatory mites per T. urticae was consequently found to be considerably higher in the organic compared to the conventional strawberry fields, approaching the recommended ratio for biological pest control of T. urticae. The abundance of insect predators was not different between the two cropping systems, while the abundance of hymenopteran parasitoids was. A higher species richness of predatory mites was found in the conventional field margins compared to the organic field margins, while insect predator species richness was found only to be higher in the organic field edge compared to the conventional field edge. The contribution of the generalist insect predator, Anthocoris nemorum L. (Hemiptera: Anthocoridae) to control of T. urticae was investigated by molecular gut content analysis of field collected predators (Manuscript II). Based on the present results, it is not only evident that they contribute to the natural regulation of T. urticae, but also that they seem to do this from late June to early August. The proportion of predators with T. urticae DNA in their gut content decreased during this time, while the density of T. urticae only increased non-significantly.The antipredator response of T. urticae (Manuscript III) was influenced by predator specialization. Chemical cues of a specialist predator, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) induced a reduced oviposition rate of T. urticae, while chemical cues of both the specialist and the generalist predator, Orius majusculus Reut. (Hemiptera: Anthocoridae) induced an increase in dispersal rate of T. urticae. Increased dispersal of prey increases the likelihood of the prey encountering other natural enemies.The study of the tritrophic interaction between entomopathogenic fungi, arthropod predators and T. urticae as influenced by specialization of the natural enemies (Manuscript IV), revealed an effect of fungal specialization on the resulting predator behaviour. Specialist fungal spores, of Neozygites floridana Weiser and Muma (Zygomycetes: Neozygitaceae), significantly increased prey encounters by predators and increased the likelihood of predators handling prey in the presence of these spores, while generalist fungal spores, of Metarhizium brunneum (Metchnikoff) Sorokin (Ascomycota: Clavicipitaceae), significantly reduced the predation rate of T. urticae. However, behaviours such as time spent searching, feeding, resting and grooming were not significantly affected by the presence of either species of fungal spores.In conclusion, many T. urticae natural enemy interactions influence the resulting trophic dynamics in strawberry agroecosystems. Findings confirm the important role of cropping system on pest and natural enemies, and the resulting infestation levels point to the potential role of generalist insect predators to control of T. urticae in strawberry. It furthermore confirms the important role of antipredator responses and predator responses to entomopathogenic fungi as affected by specialization. The studies also raise new questions and potential avenues of further studies. These include the contribution by insect predators to control of T. urticae and larger scale studies of interactions between T. urticae predators and entomopathogenic fungi, which would expand our knowledge and ultimately benefit biological control of T. urticae in strawberry.<br/
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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