996 resultados para west Indian sweet potato weevil


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X-ray computed tomography (CT) provides an insight into the progression of dissolution in the tests of planktonic foraminifera. Four species of foraminifera (G. ruber [white], G. sacculifer, N. dutertrei and P. obliquiloculata) from Pacific, Atlantic and Indian Ocean core-top samples were examined by CT and SEM. Inner chamber walls began to dissolve at Delta[CO3**2-] values of 12-14 µmol/kg. Close to the calcite saturation horizon, dissolution and precipitation of calcite may occur simultaneously. Inner calcite of G. sacculifer, N. dutertrei and P. obliquiloculata from such sites appeared altered or replaced, whereas outer crust calcite was dense with no pores. Unlike the other species, there was no distinction between inner and outer calcite in CT scans of G. ruber. Empty calcite crusts of N. dutertrei and P. obliquiloculata were most resistant to dissolution and were present in samples where Delta[CO3**2-] ~ -20 µmol/kg. Five stages of preservation were identified in CT scans, and an empirical dissolution index, XDX, was established. XDX appears to be insensitive to initial test mass. Mass loss in response to dissolution was similar between species and sites at ~ 0.4 µg/µmol/kg. We provide calibrations to estimate Delta[CO3**2-] and initial test mass from XDX.

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Sweet potato is an important strategic agricultural crop grown in many countries around the world. The roots and aerial vine components of the crop are used for both human consumption and, to some extent as a cheap source of animal feed. In spite of its economic value and growing contribution to health and nutrition, harvested sweet potato roots and aerial vine components has limited shelf-life and is easily susceptible to post-harvest losses. Although post-harvest losses of both sweet potato roots and aerial vine components is significant, there is no information available that will support the design and development of appropriate storage and preservation systems. In this context, the present study was initiated to improve scientific knowledge about sweet potato post-harvest handling. Additionally, the study also seeks to develop a PV ventilated mud storehouse for storage of sweet potato roots under tropical conditions. In study one, airflow resistance of sweet potato aerial vine components was investigated. The influence of different operating parameters such as airflow rate, moisture content and bulk depth at different levels on airflow resistance was analyzed. All the operating parameters were observed to have significant (P < 0.01) effect on airflow resistance. Prediction models were developed and were found to adequately describe the experimental pressure drop data. In study two, the resistance of airflow through unwashed and clean sweet potato roots was investigated. The effect of sweet potato roots shape factor, surface roughness, orientation to airflow, and presence of soil fraction on airflow resistance was also assessed. The pressure drop through unwashed and clean sweet potato roots was observed to increase with higher airflow, bed depth, root grade composition, and presence of soil fraction. The physical properties of the roots were incorporated into a modified Ergun model and compared with a modified Shedd’s model. The modified Ergun model provided the best fit to the experimental data when compared with the modified Shedd’s model. In study three, the effect of sweet potato root size (medium and large), different air velocity and temperature on the cooling/or heating rate and time of individual sweet potato roots were investigated. Also, a simulation model which is based on the fundamental solution of the transient equations was proposed for estimating the cooling and heating time at the centre of sweet potato roots. The results showed that increasing air velocity during cooling and heating significantly (P < 0.05) affects the cooling and heating times. Furthermore, the cooling and heating times were significantly different (P < 0.05) among medium and large size sweet potato roots. Comparison of the simulation results with experimental data confirmed that the transient simulation model can be used to accurately estimate the cooling and heating times of whole sweet potato roots under forced convection conditions. In study four, the performance of charcoal evaporative cooling pad configurations for integration into sweet potato roots storage systems was investigated. The experiments were carried out at different levels of air velocity, water flow rates, and three pad configurations: single layer pad (SLP), double layers pad (DLP) and triple layers pad (TLP) made out of small and large size charcoal particles. The results showed that higher air velocity has tremendous effect on pressure drop. Increasing the water flow rate above the range tested had no practical benefits in terms of cooling. It was observed that DLP and TLD configurations with larger wet surface area for both types of pads provided high cooling efficiencies. In study five, CFD technique in the ANSYS Fluent software was used to simulate airflow distribution in a low-cost mud storehouse. By theoretically investigating different geometries of air inlet, plenum chamber, and outlet as well as its placement using ANSYS Fluent software, an acceptable geometry with uniform air distribution was selected and constructed. Experimental measurements validated the selected design. In study six, the performance of the developed PV ventilated system was investigated. Field measurements showed satisfactory results of the directly coupled PV ventilated system. Furthermore, the option of integrating a low-cost evaporative cooling system into the mud storage structure was also investigated. The results showed a reduction of ambient temperature inside the mud storehouse while relative humidity was enhanced. The ability of the developed storage system to provide and maintain airflow, temperature and relative humidity which are the key parameters for shelf-life extension of sweet potato roots highlight its ability to reduce post-harvest losses at the farmer level, particularly under tropical climate conditions.

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We present a molecular phylogenetic analysis of caenophidian (advanced) snakes using sequences from two mitochondrial genes (12S and 16S rRNA) and one nuclear (c-mos) gene (1681 total base pairs), and with 131 terminal taxa sampled from throughout all major caenophidian lineages but focussing on Neotropical xenodontines. Direct optimization parsimony analysis resulted in a well-resolved phylogenetic tree, which corroborates some clades identified in previous analyses and suggests new hypotheses for the composition and relationships of others. The major salient points of our analysis are: (1) placement of Acrochordus, Xenodermatids, and Pareatids as successive outgroups to all remaining caenophidians (including viperids, elapids, atractaspidids, and all other "colubrid" groups); (2) within the latter group, viperids and homalopsids are sucessive sister clades to all remaining snakes; (3) the following monophyletic clades within crown group caenophidians: Afro-Asian psammophiids (including Mimophis from Madagascar), Elapidae (including hydrophiines but excluding Homoroselaps), Pseudoxyrhophiinae, Colubrinae, Natricinae, Dipsadinae, and Xenodontinae. Homoroselaps is associated with atractaspidids. Our analysis suggests some taxonomic changes within xenodontines, including new taxonomy for Alsophis elegans, Liophis amarali, and further taxonomic changes within Xenodontini and the West Indian radiation of xenodontines. Based on our molecular analysis, we present a revised classification for caenophidians and provide morphological diagnoses for many of the included clades; we also highlight groups where much more work is needed. We name as new two higher taxonomic clades within Caenophidia, one new subfamily within Dipsadidae, and, within Xenodontinae five new tribes, six new genera and two resurrected genera. We synonymize Xenoxybelis and Pseudablabes with Philodryas; Erythrolamprus with Liophis; and Lystrophis and Waglerophis with Xenodon.

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Plants synthesize a variety of molecules to defend themselves against an attack by insects. Talisin is a reserve protein from Talisia esculenta seeds, the first to be characterized from the family Sapindaceae. In this study, the insecticidal activity of Talisin was tested by incorporating the reserve protein into an artificial diet fed to the velvetbean caterpillar Anticarsia gemmatalis, the major pest of soybean crops in Brazil. At 1.5% (w/w) of the dietary protein, Talisin affected larval growth, pupal weight, development and mortality, adult fertility and longevity, and produced malformations in pupae and adult insects. Talisin inhibited the trypsin-like activity of larval midgut homogenates. The trypsin activity in Talisin-fed larvae was sensitive to Talisin, indicating that no novel protease-resistant to Talisin was induced in Talisin-fed larvae. Affinity chromatography showed that Talisin bound to midgut proteinases of the insect A. gemmatalis, but was resistant to enzymatic digestion by these larval proteinases. The transformation of genes coding for this reserve protein could be useful for developing insect resistant crops. (C) 2010 Elsevier Inc. All rights reserved.

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No information is available on the decomposition and nutrient release pattern of Piper aduncum and Imperata cylindrica despite their importance in shifting cultivation systems of Papua New Guinea and other tropical regions. We conducted a litter bag study (24 weeks) on a Typic Eutropepts in the humid lowlands to assess the rate of decomposition of Piper aduncum, Imperata cylindrica and Gliricidia sepium leaves under sweet potato (Ipomoea batatas). Decomposition rates of piper leaf litter were fastest followed closely by gliricidia, and both lost 50% of the leaf biomass within 10 weeks. Imperata leaf litter decomposed much slower and half-life values exceeded the period of observation. The decomposition patterns were best explained by the lignin plus polyphenol over N ratio which was lowest for piper (4.3) and highest for imperata (24.7). Gliricidia leaf litter released 79 kg N ha(-1), whereas 18 kg N ha(-1) was immobilised in the imperata litter. The mineralization of P was similar for the three species, but piper litter released large amounts of K. The decomposition and nutrient release patterns had significant effects on the soil. The soil contained significantly more water in the previous imperata plots at 13 weeks due to the relative slow decomposition of the leaves. Soil N levels were significantly reduced in the previous imperata plots due to immobilisation of N. Levels of exchangeable K were significantly increased in the previous piper plots due to the large addition of K. It can be concluded that piper leaf litter is a significant and easily decomposable source of K which is an important nutrient for sweet potato. Gliricidia leaf litter contained much N, whereas imperata leaf litter releases relatively little nutrients and keeps the soil more moist. Gliricidia fallow is more attractive than an imperata fallow for it improves the soil fertility and produces fuelwood as additional saleable products.

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The dispersal flights of West Indian drywood termite, Cryptotermes brevis (Walker) (Isoptera: Kalotermitidae) were surveyed in the major cities of Azores. The sampling device used to estimate termite density consisted of a yellow adhesive trap (size 45 by 24 cm), placed with an artificial or natural light source in a dark attic environment. In addition, data from two other projects were used to improve the knowledge about the geographical distribution of the species. The level of infestation in the two main Azorean towns differed, with high levels in the houses of Angra do Heroísmo, whereas in Ponta Delgada, there are fewer houses with high levels of infestation. The infestation in Ponta Delgada shows a pattern of spreading from the center outward to the city's periphery, whereas in Angra do Heroísmo, there was a pattern of spreading outward from several foci. The heavy infestation observed in Angra do Heroísmo and the clear increase of infestation levels observed from 2010 to 2011 is a reason for concern and calls for an urgent application of an Integrated Pest Management (IPM) control strategy.

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Vitamin A deficiency is a widespread public health problem in Sub-Saharan Africa. This paper analyzes the impact of a food-based intervention to fight vitamin A deficiency using orange-fleshed sweet potato (OFSP). We conducted a randomized evaluation of OFSP-related training to female farmers in Mozambique, in which the treatment group was taught basic concepts of nutrition, and OFSP-planting and cooking skills. We found encouraging evidence of changes in behavior and attitudes towards OFSP consumption and planting, and considerable increases in nutrition-related knowledge, as well as knowledge on cooking and planting OFSP.

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Economics from the NOVA – School of Business and Economics

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La batata se ubica en el séptimo lugar como cultivo destinado a la alimentación humana, y en el quinto luego de arroz, trigo, maíz y mandioca. Globalmente, existen 8 millones de hectáreas plantadas con batata y, aproximadamente el 95% de esa superficie se ubica en más de un centenar de países en desarrollo. En Argentina, la región pampeana (Buenos Aires, Córdoba y Santa Fe) y el NEA representan el 83% de la superficie plantada. Córdoba y Buenos Aires constituyen las principales provincias productoras. A pesar de su importancia potencial en la alimentación humana y animal, como producto exportable y para industrialización, se viene registrando una marcada reducción en el área cultivada con esta hortícola y, entre las causas más relevantes que determinan este fenómeno, se encuentran las enfermedades virales. Históricamente estas patologías han sido la principal limitante en la producción de este cultivo en Argentina y, especialmente en Córdoba. Recientemente y, tras brindar solución al grave problema ocasionado por el “enanismo clorótico” (Sweet potato chlorotic dwarf disease), virosis que afectó al cv Morada INTA en la década del 90, se observó, en nuestra provincia, la aparición de una severa sintomatología viral en lotes de producción implantados con el cv Arapey INIA, genotipo de creciente difusión en el cultivo por sus buenas características agronómicas. En virtud de dicha sintomatología, se sugiere que en la nueva patología viral se halla involucrado más de un agente etiológico y que la misma produce daños económicos en la producción de Arapey INIA. Por otra parte, la identificación de el/los virus presentes en la nueva patología es el primer eslabón para la búsqueda de resistencia a los mismos. Se supone, además, que, en germoplasma selecto de batata existen fuentes de resistencia a el/los virus involucrados y, que, al menos uno de los agentes patógenos de esta virosis de Arapey INIA, es transmitido por moscas blancas. Se propone, como paso inicial para el control de la nueva etiología: caracterizar biológica, serológica y molecularmente a el/los virus involucrados en ella; preparar reactivos de diagnóstico para los mismos y evaluar la gravedad de esta virosis a través de la estimación de su incidencia, prevalencia y severidad y de los daños que provoca sobre los componentes de rendimiento, en zonas productoras de la provincia de Córdoba. Por otra parte y, debido a que una de las principales formas de control de estas enfermedades es a través del empleo de germoplasma resistente y, considerando que la mayoría de los cultivares comerciales de batata, incluído Arapey INIA poseen escasa variabilidad genética por ser monoclonales, se pretende explorar molecularmente para genes de resistencia en aproximadamente 30 genotipos (clones) promisorios procedentes de la EEA INTA San Pedro ( Bs.As.), empleados como parentales en policruzamientos, además de hacerlo en el genotipo bajo estudio (Arapey INIA).

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Using artificial solid diets, experiments were performed with Anastrepha obliqua (Macquart, 1835) wild females in order to verify the influence of different quantities of brewer yeast on the performance and compensation behavior to unbalanced diets ingestion. The observed parameters were egg production, ingestion, diet efficiency and survival in the reproductive phase. Results indicated that there was no compensatory ingestion to different quantities of yeast and that the diet with 12.5g of yeast provided the best performance. The absence of compensatory ingestion is discussed based on the yeast phagostimulation and on the costs involved in solid diets ingestion. The relation between the analyzed parameters and the protein quantities in the diet were discussed.

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Malpighia emarginata Sessé & Mociño ex DC. or West Indian cherry (acerola) is a wild plant originated in southern Mexico, Central America and the northern region of South America. The species was introduced to Brazil about 60 years ago and now the country is the world's biggest producer. Even though the fruits of acerola have high commercial value, as they are an important source of the natural vitamin C, very little chromosome information is available for this species. Previous studies showed that most Malpighia species are diploids, including M. emarginata with 2n = 20. In the present paper, the chromosome number of acerola was confirmed, and for the first time, its karyotype was described, providing the identification of the homologues for the ideogram construction. The acerola chromosomes are small (1.71 to 2.56 µm) and metacentric with the exception of chromosome 2 that is classified as submetacentric. In addition, it is recommended a protocol to produce rooted-plantlets in vitro for mitotic studies that could be also used for micropropagation of acerola.