La causa parasitaria de la "seca" de los Quercus

La “Seca” de los Quercus es una enfermedad compleja que, en la península Ibérica, afecta principalmente a encinas y alcornoques, tanto a árboles agrupados como dispersos. La causa parasitaria más importante que contribuye al desarrollo de esta enfermedad es la actuación del hongo Phytophthora cinnamomi Rands. Este parásito primario habitante del suelo se detectó en España a finales de los años 80, estando en la actualidad muy presente en las comunidades autónomas de: Andalucía, Castilla La Mancha, Castilla y León, Extremadura y Madrid. En este artículo se explica de forma compresible los caracteres morfológicos del agente parasitario, su actividad como agente patógeno causal de la enfermedad y su dinámica (reproducción, conservación y dispersión).___________________________________The “Seca” (oak decline disease) of the Quercus trees is a complex disease that in the Iberian peninsula attack the holm oak and corck oak both in clusters and dispersed trees. The parasite cause more important that contributes to develop of these disease is the activity of the fungus Phytophthora cinnamomi Rands. This pathogen is a primary parasite soil habitant and was detected in Spain at the end the 80’s. Current this pathogen is present in the Autonomic Comunities of Andalusian, , Castilla La Mancha, Castilla y León, Extremadura and Madrid. In the text is indicate in understandable way the morpholgical characters of the parasite agent, its pathogen activity as well as its dynamic (reproduction, conservation and dispersion)

Periodically rippled graphene: growth and spatially resolved electronic structure

We studied the growth of an epitaxial graphene monolayer on Ru(0001). The graphene monolayer covers uniformly the Ru substrate over lateral distances larger than several microns reproducing the structural defects of the Ru substrate. The graphene is rippled with a periodicity dictated by the difference in lattice parameter between C and Ru. The theoretical model predict inhomogeneities in the electronic structure. This is confirmed by measurements in real space by means of scanning tunnelling spectroscopy. We observe electron pockets at the higher parts of the ripples.Comment: 5 page

Periodically modulated geometric and electronic structure of graphene on Ru(0001)

We report here on a method to fabricate and characterize highly perfect, periodically rippled graphene monolayers and islands, epitaxially grown on single crystal metallic substrates under controlled UHV conditions. The periodicity of the ripples is dictated by the difference in lattice parameters of graphene and substrate, and, thus, it is adjustable. We characterize its perfection at the atomic scale by means of STM and determine its electronic structure in the real space by local tunnelling spectroscopy. There are periodic variations in the geometric and electronic structure of the graphene monolayer. We observe inhomogeneities in the charge distribution, i.e a larger occupied Density Of States at the higher parts of the ripples. Periodically rippled graphene might represent the physical realization of an ordered array of coupled graphene quantum dots. The data show, however, that for rippled graphene on Ru(0001) both the low and the high parts of the ripples are metallic. The fabrication of periodically rippled graphene layers with controllable characteristic length and different bonding interactions with the substrate will allow a systematic experimental test of this fundamental problem.Comment: 12 pages. Contribution to the topical issue on graphene of Semiconductor Science and Technolog

Parasitism of Spalangia cameroni (Hymenoptera, Pteromalidae), an idiobiont parasitoid on pupae of Ceratitis capitata (Diptera, Tephritidae)

Spalangia cameroni Perkins, 1910 is a pteromalid hymenopteran, well known as a pupal parasitoid of flies belonging to different taxonomic families in the order Diptera, as Muscidae, Sarcophagidae and Anthomyiidae. This species is being used as a biological control agent against the housefly (Musca domestica) and the stable fly (Stomoxys calcitrans). In the family Tephritidae it was known as a parasitoid of Anastrepha suspensa, Dacus cucurbitae and D. passiflorae, but recently it has been described as a parasitoid of the Mediterranean Fruit Fly, Ceratitis capitata, in the Valencian Community (Spain). Due to the importance of that fruit fly species as a serious pest on citrus and fruit trees, it has been started the rearing and the biological study of S. cameroni in laboratory conditions, in order to know its ability to be used in the biological control of the medfly. Biological and parasitic parameters of the insect, as adult longevity, female fecundity and fertility, influence of host age and temperature on parasitism and female ability in searching the host buried in the ground, are being analysed

Hongos asociados al decaimiento de los bosques de enebros (Juniperus spp.) en áreas de montaña del mediterráneo español

En el transcurso de 2004, tuvimos conocimiento de que los bosques de enebros (Juniperus spp.) de áreas de montaña de la Comunidad Valenciana (SE España) llevaban años afectados por severos procesos de decaimiento. Dicha sintomatología fue principalmente observada e investigada en la Puebla de San Miguel del Rincón de Ademuz (Valencia) y en el macizo de Penyagolosa y L’Alt Maestrat (Castellón). Las áreas afectadas consistían en pies de planta infectados o sintomáticos que mostraban varios grados de afección, desde clorosis primaria, hasta la existencia de individuos completamente desfoliados y muertos. Las muestras recolectadas en las áreas afectadas fueron estudiadas para caracterizar e identificar los diferentes agentes fúngicos que pudieran ser la causa primaria o secundaria de la sintomatología observada en las masas de enebros prospectadas. Algunos de los hongos repetidamente aislados fueron: Phaeostoma juniperina, Gymnosporangium clavariiforme, Phellinus ferruginosus y Coniophora arida. La presente contribución se centra en el estudio de los dos últimos táxones citados, los cuales parecen estar relacionados con el deterioro y el decaimiento de las masas de Juniperus spp. en las áreas de estudio. El estudio sistemático de estas especies ha incluido el empleo simultáneo de técnicas taxonómicas clásicas (morfología comparativa, estudio de cultivos, etc.) fitopatológicas (inoculación “in vitro” de material vegetal en laboratorio) y moleculares (identificación mediante la secuenciación directa del ADN ribosomal)

Helium reflectivity and Debye temperature of graphene grown epitaxially on Ru(0001)

It is shown that the surface of an epitaxial graphene monolayer grown on Ru(0001) could be used as a quite efficient external mirror for He-atom microscopy, with a specular reflectivity of 20% of the incident beam. Furthermore, the system is stable up to 1150 K, and the He reflectivity remains almost unchanged after exposure to air. Additionally, the high reflectivity for H2 molecules (11%) opens up the development of a H2 microprobe suitable for lithography. The Debye temperature for this epitaxial graphene monolayer has been determined from a study of the temperature dependence of the He specular intensity as a function of incident parameters. A value of 1045 K has been obtained, which is much higher than the 590 K reported for graphite under similar conditions, and close to the value of 1287 K calculated for isolated grapheneThis work was supported by the Ministerio de Educación y Ciencia through the program CONSOLIDER-INGENIO on Molecular Nanoscience (Project No. CSD 2007-00010), Project No. FIS2010-18847, and a Juan de la Cierva grant (A.P.), and by Comunidad de Madrid through the program NANOBIOMAGNE