5,950 research outputs found

    Efeito da Azadiractina sobre Chaetosiphon fragaefolli (Cockerell, 1901) (Hemiptera: Aphididae) na cultura do morangueiro.

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    O pulgão-verde Chaetosiphon fragaefolli é o principal inseto-praga da cultura do morangueiro. Neste trabalho, foi avaliado o efeito da azadiractina para o controle do inseto em laboratório e casa de vegetação. Os tratamentos avaliados foram a azadiractina (Azamax®, 100; 200 e 300 ml.100L-1) comparado com o tiametoxam (Actara 250 WG®, 10 g.100L-1), lambda-cialotrina (Karate Zeon 50 CS®, 80 ml.100L-1) e uma testemunha (água). Os produtos foram pulverizados sobre plantas de morangueiro da cultivar Aromas infestadas artificialmente em casa de vegetação. A azadiractina foi equivalente a lambda-cialotrina e ao tiametoxam no controle de C. fragaefolii desde que realizada uma segunda pulverização sete dias após a primeira. A persistência biológica dos inseticidas lambda-cialotrina e tiametoxam foi superior a 28 dias, com um controle de 75% da população de pulgões, enquanto azadiractina apresentou menor persistência biológica, controlando 70% da população por sete dias

    N=2-Maxwell-Chern-Simons model with anomalous magnetic moment coupling via dimensional reduction

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    An N=1--supersymmetric version of the Cremmer-Scherk-Kalb-Ramond model with non-minimal coupling to matter is built up both in terms of superfields and in a component-field formalism. By adopting a dimensional reduction procedure, the N=2--D=3 counterpart of the model comes out, with two main features: a genuine (diagonal) Chern-Simons term and an anomalous magnetic moment coupling between matter and the gauge potential.Comment: 15 pages, Latex; one reference corrected; To be published in the Int. J. Mod. Phys.

    Effect of Insecticides Sprayed on Leaves and Applied via Soil to Aphis illinoisensis Shimer, 1866 (Hemiptera: Aphididae) on Grapevines

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    High infestations by the grapevine aphid Aphis illinoisensis (Hemiptera: Aphididae) have been observedin vineyards in southern Brazil, retarding plant growth and causing premature berry drop. This studyevaluated the effect of insecticides on the control of the species in two experiments carried out in agreenhouse. The first control experiment for A. illinoisensis was conducted with seedlings of Vitis viniferavar. ‘Cabernet Franc’ to assess the effect of azadirachtin (Azamax®) at dosages of 2.4 and 3.6 mL a.i.(active ingredient)/100 L of water, with reapplication seven days after the first application (DAFA). Tocompare its effect, the neonicotinoids imidacloprid (Provado 200 SC®) and thiamethoxam (Actara 250WG®) were sprayed at dosages of 8 mL or g a.i./100 L of water in foliar application without reapplication.The second experiment compared the effect on A. illinoisensis by spraying these neonicotinoids at dosagesof 8 mL or g a.i./100 L in foliar applications and of 0.05 mL or g a.i./100 L applied in the soil. Evaluationswere performed at 0, 1, 5, 7, 10 and 14 DAFA. Imidacloprid and thiamethoxam effectively controlled A.illinoisensis in both forms of application [soil and foliar], while azadirachtin at the dosage of 3.6 ml a.i./100L reapplied seven days after the first application provided 55.7% control. In conclusion, A. illinoisensis canbe controlled effectively by employing neonicotinoids in the soil, while azadirachtin can be an alternativeto reduce infestation pressure

    Self-dual vortices in a Maxwell-Chern-Simons model with non-minimal coupling

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    We find self-dual vortex solutions in a Maxwell-Chern-Simons model with anomalous magnetic moment. From a recently developed N=2-supersymmetric extension, we obtain the proper Bogomol'nyi equations together with a Higgs potential allowing both topological and non-topological phases in the theory.Comment: 12 pages, 9 figures, 2 tables; some typos corrected, one reference updated. To be published in the Int. J. Mod. Phys. A (1999

    Effect of insecticides sprayed on leaves and applied via soil to Aphis illinoisensis Shimer, 1866 (Hemiptera: Aphididae) on grapevines.

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    High infestations by the grapevine aphid Aphis illinoisensis (Hemiptera: Aphididae) have been observed in vineyards in southern Brazil, retarding plant growth and causing premature berry drop. This study evaluated the effect of insecticides on the control of the species in two experiments carried out in a greenhouse. The first control experiment for A. illinoisensis was conducted with seedlings of Vitis vinifera var. ‘Cabernet Franc’ to assess the effect of azadirachtin (Azamax®) at dosages of 2.4 and 3.6 mL a.i. (active ingredient)/100 L of water, with reapplication seven days after the first application (DAFA). To compare its effect, the neonicotinoids imidacloprid (Provado 200 SC®) and thiamethoxam (Actara 250 WG®) were sprayed at dosages of 8 mL or g a.i./100 L of water in foliar application without reapplication. The second experiment compared the effect on A. illinoisensis by spraying these neonicotinoids at dosages of 8 mL or g a.i./100 L in foliar applications and of 0.05 mL or g a.i./100 L applied in the soil. Evaluations were performed at 0, 1, 5, 7, 10 and 14 DAFA. Imidacloprid and thiamethoxam effectively controlled A. illinoisensis in both forms of application [soil and foliar], while azadirachtin at the dosage of 3.6 ml a.i./100 L reapplied seven days after the first application provided 55.7% control. In conclusion, A. illinoisensis can be controlled effectively by employing neonicotinoids in the soil, while azadirachtin can be an alternative to reduce infestation pressure. Key words: Grapevine aphid, chemical control, pest management, azadirachti

    The potential of Red Supergiants as extra-galactic abundance probes at low spectral resolution

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    Red Supergiants (RSGs) are among the brightest stars in the local universe, making them ideal candidates with which to probe the properties of their host galaxies. However, current quantitative spectroscopic techniques require spectral resolutions of R>17,000, making observations of RSGs at distances greater than 1Mpc unfeasible. Here we explore the potential of quantitative spectroscopic techniques at much lower resolutions, R ~2-3000. We take archival J-band spectra of a sample of RSGs in the Solar neighbourhood. In this spectral region the metallic lines of FeI, MgI, SiI and TiI are prominent, while the molecular absorption features of OH, H_2O, CN and CO are weak. We compare these data with synthetic spectra produced from the existing grid of model atmospheres from the MARCS project, with the aim of deriving chemical abundances. We find that all stars studied can be unambiguously fit by the models, and model parameters of log g, effective temperatures Teff, microturbulence and global metal content may be derived. We find that the abundances derived for the stars are all very close to Solar and have low dispersion, with an average of [logZ]=0.13+/-0.14. The values of Teff fit by the models are ~150K cooler than the stars' literature values for earlier spectral types when using the Levesque et al. temperature scale, though this temperature discrepancy has very little systematic effect on the derived abundances as the equivalent widths (EWs) of the metallic lines are roughly constant across the full temperature range of RSGs. Instead, elemental abundances are the dominating factor in the EWs of the diagnostic lines. Our results suggest that chemical abundance measurements of RSGs are possible at low- to medium-resolution, meaning that this technique is a viable infrared-based alternative to measuring abundance trends in external galaxies. [Abridged]Comment: 10 pages, 7 figures. Accepted for publication in MNRAS

    Teias de prejuízo.

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    O ácaro-rajado (Tetranychus urticae) é uma das principais pragas que atacam a cultura do morango. Apesar do tamanho minúsculo, sua presença em altas populações é facilmente perceptível pela formação de teias nas plantas. Os danos vão da redução da taxa fotossintética até a diminuição no número e no peso dos frutos. O emprego de predadores e de produtos naturais à base de nim surge como alternativa promissora para o controle

    Bioecologia, monitoramento e controle do ácaro-rajado com o emprego da azadiractina e ácaros predadores na cultura do morangueiro.

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    Essa circular técnica tem como objetivo apresentar informações sobre a bioecologia, formas de monitoramento e controle do ácaro-rajado através do emprego de ácaros predadores e de uma formulação comercial à base de azadiractina, que podem ser empregados de forma isolada ou associados à cultura do morangueiro.bitstream/item/31206/1/cir083.pd

    Bioecologia, monitoramento e controle de Chaetosiphon fragaefolli (Cockerell, 1901) (Hemiptera: Aphididae) na cultura do morangueiro.

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    Esta circular técnica tem como objetivo apresentar informações sobre a taxonomia, a morfologia, a bioecologia, estratégias para o monitoramento e o controle do pulgão-verde, principal espécie associada ao cultivo do morangueiro no Estado do Rio Grande do Sul.bitstream/item/48473/1/Circular-Tecnica-84.pd
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