Evaluation du potentiel insecticide de l’huile essentielle de Ocimum canum Sims sur Aphis gossypii Glover (Homoptera : Aphididae) au Togo

Afin de contribuer à l’élaboration d’une stratégie de gestion intégrée des ravageurs associés à la culture cotonnière, le potentiel insecticide de l’huile essentielle de Ocimum canum et de son composé majoritaire le terpinéol-4 a été évalué sur les adultes d’Aphis gossypii, puceron du cotonnier. Les tests biologiques ont été effectués en laboratoire selon la méthodologie Insecticide Resistance Action Commitee (IRAC) N° 1 Version 2. Les résultats de ces tests ont révélé que l’huile essentielle de O. canum et le terpinéol-4 possèdent de remarquables propriétés aphicides. Ils ont induit 100% de mortalité des pucerons adultes à la concentration minimale de 4 μl.ml-¹. Les DL50 mesurées ont indiqué les valeurs de 1,49 μl.ml-¹ et 2,06 μl.ml-¹ respectivement pour l’huile essentielle et le terpinéol-4. Les essais au champ seront nécessaires pour confirmer l’intérêt pratique de ces résultats dans l’élaboration d’un pesticide naturel contre ce puceron.Keywords: Cotonnier, terpinéol-4, puceron du cotonnier, bio pesticides, propriétés aphicide

Efficacite des bioinsecticides a base de l’huile essentielle de Cymbopogon schoenanthus (L.) spreng contre les punaises rouges (Dysdercus voelkeri, schmidt) en culture cotonniere au Togo

De nos jours la lutte contre les punaises rouges, ravageurs du cotonnier, se résume en l’utilisation d’insecticides chimiques de synthèse. Nombre de ces produits utilisés sont persistants et leur grande toxicité sur la santé humaine et environnementale est préoccupante. Dans la recherche d’alternatives aux insecticides chimiques de synthèse, ce présent travail de recherche vise à évaluer le potentiel insecticide des émulsions aqueuses à base de l’huile essentielle de Cymbopogon schoenanthus (L.) contre Dysdercus voelkeri, un des redoutables ravageurs du cotonnier au Togo. Des émulsions aqueuses à différentes concentrations ont été utilisées dans les traitements phytosanitaires sur culture cotonnière en comparaison avec des insecticides binaires vulgarisés (lambdacyhalothrine/profénofos 15/300 gha-1 et cyperméthrine/acétamipride 36/8 gha-1). Les dénombrements de D. voelkeri sur les plantes cibles de chaque parcelle élémentaire ont montré que la dose la plus forte de l’émulsion (6%) et le témoin positif (insecticide vulgarisé) ont été plus efficaces avec des densités de populations faibles de punaises respectivement de 7,14 ± 1,46 et 4,86 ± 1,84 punaises/plant. Contrairement les autres doses (4 et 2%) d’émulsions à base de l’huile essentielle de C. schoenanthus ont eu dans leurs parcelles respectivement 39,57±5,81 et 45,28±3,92 punaises/plant et le témoin (55,71 ± 5,23 punaises/plant). L’analyse sanitaire des jeunes capsules tombées sous les cotonniers a révélé que la dose la plus forte de l’émulsion (6%) et le témoin positif ont réduit respectivement les piqûres des punaises de 71,40 et 72,33% par rapport au témoin. Les taux de réduction des piqûres dans les parcelles à traitements de 4 et 2% de l’émulsion ont été faibles avec des taux respectifs de 55,32% et 22,83%. Ces résultats révèlent clairement que l’émulsion aqueuse formulée et testée dans l’étude peut réduire significativement les attaques de ces ravageurs. Cette étude montre la possibilité de l'utilisation de l’huile essentielle de C.schoenanthus comme matière première dans la formulation de biopesticide comme alternative aux insecticides chimiques de synthèse dans la lutte contre les punaises rouges du cotonnier au Togo

Improving youth livelihoods : Ivory Coast

French version available in IDRC Digital LibraryThis policy brief reviews young people’s participation in the Ivory Coast economy. Unemployment rates are higher in urban areas, and youth experience higher unemployment rates than adults, with 9.7 percent of young men and 15 percent of young women unemployed. Only 9 percent of jobs are in the formal private or public sectors in Ivory Coast/Cote d’Ivoire. The issue of underemployment relates to increasingly prevalent forms of informal employment. The youth employment challenge requires specific action from leaders, yet much about young people's employment experiences remains unknown. Statistics on employment are often inconsistent and unavailable.MasterCard Foundatio

Finite-dimensional analogs of string s <-> t duality and pentagon equation

We put forward one of the forms of functional pentagon equation (FPE), known from the theory of integrable models, as an algebraic explanation to the phenomenon known in physics as st duality. We present two simple geometrical examples of FPE solutions, one of them yielding in a particular case the well-known Veneziano expression for 4-particle amplitude. Finally, we interpret our solutions of FPE in terms of relations in Lie groups.Comment: LaTeX, 12 pages, 6 eps figure

Parton Branching in Color Mutation Model

The soft production problem in hadronic collisions as described in the eikonal color mutation branching model is improved in the way that the initial parton distribution is treated. Furry branching of the partons is considered as a means of describing the nonperturbative process of parton reproduction in soft interaction. The values of all the moments, and $C_q$, for q=2,...,5, as well as their energy dependences can be correctly determined by the use of only two parameters.Comment: 8 pages (LaTeX) + 2 figures (ps files), submitted to Phys. Rev.

Analyses of multiplicity distributions with \eta_c and Bose-Einstein correlations at LHC by means of generalized Glauber-Lachs formula

Using the negative binomial distribution (NBD) and the generalized Glauber-Lachs (GGL) formula, we analyze the data on charged multiplicity distributions with pseudo-rapidity cutoffs \eta_c at 0.9, 2.36, and 7 TeV by ALICE Collaboration and at 0.2, 0.54, and 0.9 TeV by UA5 Collaboration. We confirm that the KNO scaling holds among the multiplicity distributions with \eta_c = 0.5 at \sqrt{s} = 0.2\sim2.36 TeV and estimate the energy dependence of a parameter 1/k in NBD and parameters 1/k and \gamma (the ratio of the average value of the coherent hadrons to that of the chaotic hadrons) in the GGL formula. Using empirical formulae for the parameters 1/k and \gamma in the GGL formula, we predict the multiplicity distributions with \eta_c = 0.5 at 7 and 14 TeV. Data on the 2nd order Bose-Einstein correlations (BEC) at 0.9 TeV by ALICE Collaboration and 0.9 and 2.36 TeV by CMS Collaboration are also analyzed based on the GGL formula. Prediction for the 3rd order BEC at 0.9 and 2.36 TeV are presented. Moreover, the information entropy is discussed

Next-to-MLLA corrections to single inclusive kt-distributions and 2-particle correlations in a jet

The hadronic kt-spectrum inside a high energy jet is determined including corrections of relative magnitude O{\sqrt{\alpha_s}} with respect to the Modified Leading Logarithmic Approximation (MLLA), in the limiting spectrum approximation (assuming an infrared cut-off Q0 =Lambda_{QCD}) and beyond Q_0\ne\Lambda_{QCD}. The results in the limiting spectrum approximation are found to be, after normalization, in impressive agreement with preliminary measurements by the CDF collaboration, unlike what occurs at MLLA, pointing out small overall non-perturbative contributions. Within the same framework, 2-particle correlations inside a jet are also predicted at NMLLA and compared to previous MLLA calculations.Comment: 35 pages and 39 figures. Comments, appendices, figures, references added. Version to appear in Phys. Rev.

Total Cross Section, Inelasticity and Multiplicity Distributions in Proton -- Proton Collisions

Multiparticle production in high energy proton -- proton collisions has been analysed in the frame of Strongly Correlated Quark Model (SCQM) of the hadron structure elaborated by the author. It is shown that inelasticity decreases at high energies and this effect together with the total cross section growth and the increasing with collision energy the masses of intermediate clusters result in the violation of KNO -- scaling.Comment: 21 pages, 11 figures, submitted to Yad. Fisik

Microcanonical Jet-fragmentation in proton-proton collisions at LHC Energy

In this paper, we show that the distribution of the longitudinal momentum fraction of charged hadrons $dN/dz$ inside jets stemming from proton-proton collisions at $\sqrt{s}$ = 7 TeV center of mass energy can be described by a statistical jet-fragmentation model. This model combines microcanonical statistics and super-statistics induced by multiplicity fluctuations. The resulting scale dependence of the parameters of the model turns out to be similar to what was observed in electron-positron annihilations in Urmossy, Barnaf\"oldi, and Bir\'o.Comment: 7 pages, 8 figure

Scaling Distributions of Quarks, Mesons and Proton for all pTp_T, Energy and Centrality

We present the evidences for the existence of a universal scaling behavior of the production of $\pi^0$ at all transverse momenta in heavy-ion collisions at all centralities and all collision energies. The corresponding scaling behavior of the quarks is then derived just before the quarks recombine with antiquarks to form the pions. The degradation effect of the dense medium on the quark $p_T$ is derived from the scaling distribution. In the recombination model it is then possible to calculate the $p_T$ distributions of the produced proton and kaon, which are scaling also. Experimentally verifiable predictions are made. Implications of the existence of the scaling behavior are discussed.Comment: 10 pages in RevTeX, including 14 figures in eps file