1,720,954 research outputs found
Feeding perturbation and toxic activity of five Chrysanthemum species crude extracts against Spodoptera littoralis (Boisduval) (Lepidoptera; Noctuidae)
No full textThe effect of the whole methanol extracts of five Chrysanthemum species on feeding and performance of Spodoptera littoralis (Boisduval) larvae has been investigated in vitro. The extracts exhibited antifeeding and phagostimulating activities against cotton leafworm larvae when applied either on leaf discs or incorporated into an artificial diet. Under chosen conditions, the antifeedant index calculated over 24 h for sixth instar larvae significantly varied from 78.55 for Chrysanthemum segetum L. to -44.18 for Chrysanthemum fuscatum Desf. at the dose of 1000 ppm. Toxicity of the extracts was manifested by a high mortality, reduced growth rates, and low weight gain by larvae fed on diets containing 1000-10,000 ppm of the extract. Anyone of the larvae treated with Chrysanthemum macrotum (D.R.) Ball. leaves crude extract survived to pupation at the two higher concentrations. The time to pupation increased for Chrysanthemum grandiflorum flowers crude extract from 11.40±0.93 to 28.93±10.92 days as the extract concentration in the diet increased from 0 to 10,000 ppm. The ingestion of crude extract by the third instar larvae reduced significantly the consumption, growth and utilisation of the ingested and digested food, and reduced digestibility. The crude extract of the leaves of C. macrotum, dissolved in acetone and topically applied on sixth instar larvae, showed a quite high mortality (95%). These results suggest the presence in the extracts of anti-feeding and/or toxic substances, active by consumption and topical application. The identification of these compounds and their action mode will be object of further studie
Insecticidal and anti-appetent activities of four Chrysanthemum species against Tribolium confusum Du Val (Coleoptera: Tenebrionidae)
No full textInsect pests are one of the major factors limiting the production and the storage of agricultural products. The use of synthetic pesticides limits the damage of these pests. However, the effectiveness of these products is continually eroded by the development of resistance in these pests and serious health and ecological disadvantages were detected. It is clear that there is an urgent need for alternative control measures, which must be active against the pests, safe to humans and environmentally friendly. Evaluation of local plants as sources of protectants is one of the promising ways to fulfil this need. In this study the essential oil of four Chrysanthemum species (C. macrotum, C. trifurcatum, C. segetum and C. fuscatum) were evaluated for their insecticidal activity against Tribolium confusum using tow methods: fumigation and consumption. The essential was diluted in acetone to obtain the concentration of 1%. For the fumigant activity, 100 μl of the solution was applied on filter paper (1x2.5 cm), after evaporating the solvent, each filter paper was placed on the underside of the screw cap of a glass vial and was screwed tightly onto the vial containing ten adults of Tribolium confusum. Concerning the evaluation of the anti-appetent activity, 5 μl of each Chrysanthemum species essential oil were applied on flour disc (95% wheat semolina and 5% beer yeast). The control received only acetone and five replicates were set up for each treatment and control. The results showed that essential oil obtained from flowers of C. macrotum and those from leaves of C. trifurcatum have the highest fumigant activity and cause respectively the mortality of 48 and 40% against adults of T. confusum. The study of anti-appetent effect on larvae of T. confusum showed that C. segetum flowers essential oil has the significant feeding deterrent index (92.45±4.61) followed by the leaves essential oil obtained from C. fuscatum (71.20±19.22), without having a significant mortality on this larvae.
The study of essential oil composition of the four Chrysanthemum species highlighted their richness on mono and sesqueterpenes that are known for their insecticidal activity.
Though these findings are preliminary, they could represent the basis for further investigations on the questions raised in this work. In particular, additional research is needed to investigate the susceptibility of other stages of the insect life, such as pupae and eggs and to improve our understanding of how mono- and sesquiterpenoids act on insects. Practically, in view of a possible use of the most active mono- and sesquiterpenoids, it should be pointed out that longer exposure periods could be needed to bridge the tolerant phases of insects, some of which could be present at the time of application
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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