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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
Chemical constituents and toxicity of essential oils from three Asteraceae plants against Tribolium confusum
No full textPlants produce a high diversity of secondary metabolites with a prominent function in the protection against pests and pathogens. In this work, we studied the chemical composition and the effect of six essential oils extracted from three Asteraceae species (Heteromera fuscata, Coleostephus myconis and Mauranthemum paludosum) on nutritional indexes, adult emergence and larva and adult toxicity of Tribolium confusum. Flower and leaf essential oils were obtained by hydrodistillation. The study of their chemical composition was carried out by GC-MS. The results showed that they are rich on monoand sesquiterpens. The consumption of essential oils mixed with artificial diet of T. confusum larvae showed that H. fuscata leaf essential oil delayed the insect growth, reduced the food consumption and exhibited significant food deterrent index (0.02 ± 0.01 mg/mg/j, 0.05 ± 0.02 mg/mg/j, and 71.20 ± 19.22%, respectively) on treated larvae. Topical application of Asteraceae essential oils on pupae less than 24 h of age caused malformation on emerged adults. The highest level of malformation (18%) was induced by C. myconis leaf essential. Topical application of those essential oils on T. confusum adults (10 and 14 days-old) showed higher toxicity. The highest mortality of about 41% was recorded 7 days post-treatment on adults treated with essential oils from M. paludosum leaves. These preliminary results could represent the basis for further investigations on the susceptibility of the other
developmental stages and elucidation of the mode of action of mono- and sesquiterpenoids against these insect pest
Comparison of chemical composition and bio-insecticidal activity of three Chrysanthemum species essential oils on Tribolium confusum Du Val (Coleoptera: Tenebrionidae)
No full textIn traditional agriculture, plant extracts were the most effective source to protect the food, but by the nineteenth century this practice was gradually replaced by synthetic products. However, those products are expensive and induce the insect resistance, so researches are oriented to study the insecticidal activity of plant extracts aimed to isolate active (s) compound(s). In this work we studied the insecticidal activity of essential oils of three Chrysanthemum species against Tribolium confusum. Three methods are used, such as ingestion, topical application against adults and nymphs and fumigation against adults. The results analysis showed that ingestion of artificial medium treated by essential oils causes a decrease in larvae consumption and we noticed that C. macrotum essential oil was the most antifeedant one. In addition this oil caused significant mortality (68 %) in treated larvae.
Topical application of essential oils against adults and nymphs beetle showed that C. macrotum essential oil is more toxic against adults (44%) than nymphs (28%). The analysis of fumigation results showed that the highest toxicity (48%) was caused by C. macrotum essential oil and that so it doesn’t exceed 1% in the case of C. trifurcatum and C. fuscatum. These results highlight that C. macrotum essential oil was most effective against T. confusum. Chemical analysis of different essential oils showed that C. macrotum essential oil was very rich in terpenes, where sesquiterpenes are the most abundant compounds. According these results we have determine the species and the chemical
composition of the most toxic essential oil on T. confusum. Further study will be very useful to determine the toxic compound (s)
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
Identification d'un dérivé de polyacetilène de spiroketole enol éther du Chrysanthemum macrotum L
No full textFeeding 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
Identification of an insecticidal polyacetilene derivative from Chrysanthemum macrotum leaves
No full textCompounds responsible for insecticidal properties of Chrysanthemum macrotum (D.R.) Ball. leaves against Spodoptera littoralis Boiduval caterpillars have been investigated. The screening of the insecticidal activity was performed by incorporating methanol, buthanol or ethyl acetate extracts, or some chromatographic fractions to the caterpillars’ artificial diet. It was noted that extracts and fractions ameliorated or disturbed nutritional indexes, being not always toxic for caterpillars. Among the tested fractions, one pure compound with a high insecticidal activity (percentage of mortality 66.7%) was purified. The nuclear magnetic resonance study allowed its identification as a polyacetylene derivative, in particular a spiroketal enol ether one
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
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