Evaluación de la capacidad de depredación de la especie de stratiolaelaps sp. (Acari: Laelapidae) en poblaciones de thrips palmi karny (Thysanoptera: Thripidae)

El trips del melón Thrips palmi Karny, es una plaga cosmopolita y polífaga introducida al país desde 1997 y reportada afectando los cultivos de habichuela, melón y pimentón. El control químico es la herramienta más utilizada por los agricultores, sin embargo su eficacia se ve limitada por la resistencia a los insecticidas adquirida por el insecto. Ante esta problemática el control biológico puede ser una buena opción con base en acaros Laelapidae, dado que son depredadores promisorios, las crias masivas podrían ser utilizadas como importantes agentes de manejo de plagas como Thrips, Sciariadae, Cecidomyiidae, y ácaros plaga del suelo. Con el presente estudio se pretende evaluar de la capacidad de depredación de la especie de Stratiolaelaps sp. (Acari: Laelapidae) en poblaciones de Thrips palmi Karny (Thysanoptera: Thripidae). Conocedores de la diversidad de estos ácaros en ecosistemas del Valle del Cauca y con el fin de desarrollar un método de cría de Stratiolaelaps sp., se colectaron individuos de dicha especie de acaros, en hojarasca y suelo en el corregimiento de Cisneros entre la superficie y 5,0 cm de profundidad, utilizando un cilindro de 5,0 cm de diámetro por 5,0 cm de altura; en un radio de 1 metro. Las muestras se transportaron en neveras de icopor con hielo al laboratorio de Entomología y Acarología de la Universidad Nacional de Colombia Sede Palmira. En el laboratorio las muestras de suelo y hojarasca se colocaron en bandejas mantequilleras para su conservación y posteriormente se extrajeron los ácaros depredadores del género Stratiolaelaps, los cuales se traspasaron a porrones plásticos que contenían ácaros como presa alternativa en crías masivas de la especie Tyrophagus putrescentiae Shrank (Acari: Acaridae); estos se obtuvieron de cajas petri con agar en el laboratorio de Microbiología Vegetal de la Universidad Nacional de Colombia sede Palmira. Como sustrato para mantener a Tyrophagus putrescentiae se utilizó alimento para perros. Se ofreció a los depredadores diferentes cantidades de alimento donde cada croqueta contenían 537 T. putrescentiae (4, 6, 8, 10, 12 y 14 croquetas) para establecer el numero apropiado para iniciar una cría del Laelapidae se evaluaron (25, 50, 75 y 100 individuos). Se encontró que la cría se puede mantener en porrones plásticos, a temperatura de 25 + 5°C y humedad relativa de 70 + 5%, asperjando agua periódicamente en los porrones. Se observó 100 gramos de croquetas limpias y 4 croquetas con 2148 T. putrescentiae. A los dos días se adicionan 25 adultos de Stratiolaelaps sp., y al cabo de 10 días se adicionan nuevamente 100 gramos de croquetas limpias y 4 nuevas croquetas con T. putrescentiae. Para la prueba de depredación en Thrips palmi se colectaron individuos de brotes melón, los cuales se criaron bajo condiciones de invernadero en plantas de frijol, con el fin de evaluar cuál era el estado de desarrollo de la plaga preferido. se ofrecieron ninfas de I instar, II instar, prepupas y adultos de T. palmi, se ofrecieron 5, 10, 15, 20, 25, 30, 35, 40, 45 y 50 individuos de cada uno de los diferentes estados en forma separada. En las cajas Petri que contenía las densidades de la presa (T. palmi), se colocaron Stratiolaelaps sp. en números de 2, 4, 6, 8 y 10. Cada dos horas se evaluó el consumo de thrips ofrecidos y se observó una preferencia por las prepupas y pupas ya que son estados de poco movimiento, a diferencias de las ninfas y adultos que son muy móviles dificultando la captura. Los resultados obtenidos son importantes para el desarrollo exitoso de un plan de control biológico eficaz.//Abstract: Melon Thrips palmi Karny is a cosmopolitan and polyphagous pest introduced to the country since 1997 and reported affecting beans, melons and paprika crops. Chemical control is the most used tool by farmers, however, its effectiveness is limited by the resistance to insecticides acquired by the insect. Faced with this problem, biological control may be a good choice based on Laelapidae mites, due to they are promising, massive offspring could be used as important agents of pest management as Thrips, Sciariadae, Cecidomyiidae, and soil pest mites. This research aims to evaluate the dredatory ability of the species Stratiolaelaps sp. (Acari: Laelapidae) in populations of Thrips palmi Karny (Thysanoptera: Thripidae). People aware of the diversity of these mites in the Valle del Cauca ecosystems, with the objective to develop a method of raising Stratiolaelaps sp., collected individuals of the mites´ species, these were found in the location of Cisneros, ubicated into the litter and soil between the surface and 5.0 cm deep, using a cylinder of 5.0 cm diameter by 5.0 cm height; and 1 m. of radius. The samples were transported to the Entomology and Acarology Laboratory of the National University of Colombia at Palmira in styrofoam coolers with ice. In the laboratory the soil and litter samples were placed in butter trays for conservation and after were extracted predatory mites of the genus Stratiolaelaps, those were transferred in plastic jugs containing mites as alternative prey in massive pups of the species Tyrophagus putrescentiae Shrank (Acari: Acaridae); these were obtained from agar petri dishes in the laboratory of Plant Microbiology at the National University of Colombia at Palmira. In order to keep Tyrophagus putrescentiae the substrate used was dog food. There was offered to predators different amounts of food where every kibble contained 537 T. putrescentiae (4, 6, 8, 10, 12 and 14 kibbles) to establish the appropriate number to start a breeding of Laelapidae were evaluated 25, 50, 75 and 100 individuals. It was found that the breeding can be kept in plastic jugs, providing a temperature of 25 + 5 ° C and relative humidity of 70 + 5%, sprinkling water periodically in the jugs. It was observed 100 gr. of clean kibbles and 4 kibbles with 2148 T. putrescentiae. After two days were added 25 adults of the species Stratiolaelaps sp., and after 10 days were added again 100 gr. Of clean kibbles and 4 new kibbles with T. putrescentiae. For the predation test in Thrips palmi there were collected melon’s bud individuals, which were raised under greenhouse conditions in bean plants, in order to evaluate which was the state of development of the preferred pest. There were offered nymphs of instar I and II, prepupae and adults of T. palmi, also, 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 individuals from each of the different states separately. There were placed Stratiolaelaps sp. in numbers of 2, 4, 6, 8 and 10 in Petri dishes containing prey densities (T. palmi). Every two hours was evaluated thrips consumption and a preference was observed for prepupae and pupae because those are states of little movement, unlike to nymphs and adults that are very movable difficulting the capture. The results are important for the successful development of a plan of effective biological control.Maestrí

Multifractal dimensions for critical random matrix ensembles

Based on heuristic arguments we conjecture that an intimate relation exists between the eigenfunction multifractal dimensions $D_q$ of the eigenstates of critical random matrix ensembles $D_{q'} \approx qD_q[q'+(q-q')D_q]^{-1}$, $1\le q \le 2$. We verify this relation by extensive numerical calculations. We also demonstrate that the level compressibility $\chi$ describing level correlations can be related to $D_q$ in a unified way as $D_q=(1-\chi)[1+(q-1)\chi]^{-1}$, thus generalizing existing relations with relevance to the disorder driven Anderson--transition.Comment: 6 pages, 9 figure

Marketing digital y el impacto en el posicionamiento de empresas privadas en los últimos 10 años en Latinoamérica: una revisión de la literatura científica

La investigación se basó en identificar cuáles son las acciones de comunicación que realizan las empresas en los medios digitales, para crear interacción con el consumidor con el fin de lograr posicionamiento en el mercado y en la web, basado en las tendencias online más utilizadas y efectivas para crear relacionamiento activo con los usuarios. Según la información recolectada las empresas desean distinguirse de sus competencias y llegar a su público de una manera eficaz y rápida, para poder lograr afianzarlos y que por medio de ellos lleguen a posibles consumidores. Para la investigación se realizó una revisión sistemática en las plataformas Ebsco, Redalyc y Scielo, los términos de elegibilidad fueron los siguientes, periodo de los 10 últimos años y la ubicación geográfica correspondiente a Latinoamérica, utilizando investigaciones sobre el uso e implementación del marketing digital y posicionamiento empresarial, las limitaciones presentadas fueron idioma, país y año, logrando descartar artículos no correspondientes a la pregunta de investigación. ¿Cuál es la tendencia de los estudios sobre marketing digital y su impacto en el posicionamiento de empresas privadas en los últimos diez años en Latinoamérica

The circumstellar environment of HD50138 revealed by VLTI/AMBER at high angular resolution

HD50138 is a Herbig B[e] star with a circumstellar disc detected at IR and mm wavelength. Its brightness makes it a good candidate for NIR interferometry observations. We aim to resolve, spatially and spectrally, the continuum and hydrogen emission lines in the 2.12-2.47 micron region, to shed light on the immediate circumstellar environment of the star. VLTI/AMBER K-band observations provide spectra, visibilities, differential phases, and closure phases along three long baselines for the continuum, and HI emission in Br$\gamma$ and five high-n Pfund lines. By computing the pure-line visibilities, we derive the angular size of the different line-emitting regions. A simple LTE model was created to constrain the physical conditions of HI emitting region. The continuum region cannot be reproduced by a geometrical 2D elongated Gaussian fitting model. We estimate the size of the region to be 1 au. We find the Br$\gamma$ and Pfund lines come from a more compact region of size 0.4 au. The Br$\gamma$ line exhibits an S-shaped differential phase, indicative of rotation. The continuum and Br$\gamma$ line closure phase show offsets of $\sim$-25$\pm$5 $^o$ and 20$\pm$10$^o$, respectively. This is evidence of an asymmetry in their origin, but with opposing directions. We find that we cannot converge on constraints for the HI physical parameters without a more detailed model. Our analysis reveals that HD50138 hosts a complex circumstellar environment. Its continuum emission cannot be reproduced by a simple disc brightness distribution. Similarly, several components must be evoked to reproduce the interferometric observables within the Br$\gamma$, line. Combining the spectroscopic and interferometric data of the Br$\gamma$ and Pfund lines favours an origin in a wind region with a large opening angle. Finally, our results point to an evolved source.Comment: accepted for publication in A&

Exploiting line metric reconstruction from non-central circular panoramas

In certain non-central imaging systems, straight lines are projected via a non-planar surface encapsulating the 4 degrees of freedom of the 3D line. Consequently the geometry of the 3D line can be recovered from a minimum of four image points. However, with classical non-central catadioptric systems there is not enough effective baseline for a practical implementation of the method. In this paper we propose a multi-camera system configuration resembling the circular panoramic model which results in a particular non-central projection allowing the stitching of a non-central panorama. From a single panorama we obtain well-conditioned 3D reconstruction of lines, which are specially interesting in texture-less scenarios. No previous information about the direction or arrangement of the lines in the scene is assumed. The proposed method is evaluated on both synthetic and real images

The impact of port governance and infrastructures on maritime containerized trade on the West Coast of Latin America

Latin American countries have historically had a strong dependence on trade, and are mostly characterized by being exporters of raw materials and importers of manufactured products. This fact has brought about a less negative impact of the world crisis on economic growth, mainly because of the high prices of raw materials. This paper focuses on this geographical area (the West Coast of Latin America) between 2008 and 2015, and adds to the literature by assessing institutional, port-related and economic factors that influence maritime transport. The analysis makes use of panel data models with fixed and random effects where the Hausman test has been applied in order to define a solid specification of all the ports, as well as to discount the particular peculiarities of each country. It is shown that the analysis of maritime transport requires the analysis of a number of variables apart from trade (volume of TEUs), infrastructures, superstructures (number of calls, gantry cranes), and that other variables, such as port governance, which are sometimes difficult to quantify, need also to be taken into account