A simulation model for environmental population densities, survival rates and prevalence of Boophilus decoloratus (Acari: ixodidae) using remotely sensed environmental information.

A simulation model for the African tick Boophilus decoloratus is presented. This model is based on the use of a dynamic life table that is driven by abiotic variables (temperature and vegetation status) remotely sensed (AVHRR sensor of the NOAA series of satellites) over time. The model incorporates temperature-dependent rates of egg production and development, climate-driven density-independent mortality rates, and density-dependent regulation of on-host stages. The model successfully describes both the seasonality and annual variation in the numbers of questing larvae and engorging females observed in eight sites throughout sub-Saharan Africa. Climate data from 1983 to 1999 in 10-day intervals are used as the basic input for modelling the dynamic patterns of activity at four different sites in Africa and to understand how abiotic factors can modulate the long-term life cycle of B. decoloratus.     

The Bovine Tuberculosis Campaign in Mexico： Present and Perspectives

Mexico is considered by different international organizations as a country where the bovine tuberculosis is an endemic problem. However, there are important and consistent improvements in eradicating the disease by the implementation of government policies and with the livestock organization support. The current situation of the program shows good results regarding decreasing the prevalence, and as a consequence, the risk of this disease for public health and animal health, as well as the improvement in animal production and international and national trade. Today, the bovine tuberculosis distribution is almost known in Mexico. In addition, a series of controls and indicators have been established, which allow maintain consistency and reliability in the data that are managed and analyzed.     

Volatiles emitted by Carya illinoinensis (Wang.) K. Koch as a prelude for semiochemical investigations to focus on Acrobasis nuxvorella Nuenzig (Lepidoptera: Pyralidae)

BACKGROUND: Plant volatiles have complex intra‐ and interspecific effects in the environment that include plant/herbivore interactions. Identifying the quantity and quality of volatiles produced by a plant is needed to aid the process of determining which chemicals are exerting what effects and then examining whether these effects can be manipulated to benefit society. The qualitative characterization of volatile compounds emitted by pecan, Carya illinoinensis (Wang.) K. Koch, was begun in order to establish a database for investigating how these volatiles affect Acrobasis nuxvorella Nuenzig, a monophagous pest of pecan. Headspace solid‐phase microextraction combined with gas chromatography–mass spectrometry was used for the analysis of the volatile constituents of pecan during three phenological stages (dormant buds, intact new shoot growth and intact nutlets) of the Western Schley and Wichita cultivars. RESULTS: About 111 distinct compounds were identified from the two cultivars, accounting for ～99% of the headspace volatiles. The chromatographic profiles of both varieties revealed variations in the volatile composition and proportion between cultivars, with a predominance of terpene hydrocarbons, of the sesquiterpenes class, as well as monoterpenes. CONCLUSION: The significantly higher responsiveness recorded for the larvae of A. nuxvorella to C. illinoinensis shoots indicates that the larvae may be activated by terpenes emanating from the new shoot growth. This is the first study that has examined volatiles of pecan in Mexico. Copyright © 2011 Society of Chemical Industry     

Characterization of anthocyanins from the fruits of baguaçu (Eugenia umbelliflora Berg)

Anthocyanin pigments in the berries of bagua?u (Eugenia umbelliflora Berg), a tropical fruit from Brazil, were extracted with 0.1% HCl in ethanol, and the crude anthocyanin extract was purified by Amberlite XAD-7 open-column chromatography. Six major anthocyanins were isolated by preparative HPLC, and their chemical structures were identified by spectroscopic methods (TLC, UV-vis, MS, and (1)H NMR). Delphinidin 3-O-beta-glucopyranoside, cyanidin 3-O-beta-glucopyranoside, petunidin 3-O-beta-glucopyranoside, pelargonidin 3-O-beta-glucopyranoside, peonidin 3-O-beta-glucopyranoside, and malvidin 3-O-beta-glucopyranoside were identified. On the basis of chromatographic data the total anthocyanin content was 342 mg/100 g of fresh bagua?u berries. Therefore, the concomitant presence of six anthocyanins in a single plant species makes this product promising as a new pigment source.     

Soil attributes in a furrow-irrigated bed planting system in northwest Mexico

In the Yaqui valley, northwest Mexico, wheat (Triticum aestivum L.) is grown as a winter crop followed by maize (Zea mays L.) as a summer crop both planted on beds. Straw of both crops is usually burned to facilitate seedbed preparation for the succeeding crop. Soil physical and biological attributes were determined from 1996 to 2000 from a study initiated in 1992 at the CIANO (Centro de Investigaciones Agrícolas del Noroeste) experiment station. The objective was to compare five treatments: (1) conventional tilled bed (CTB)-straw incorporated, and permanent bed (PB) with (2) straw removed, (3) straw partly removed, (4) straw retained, and (5) straw burned — on soil strength, soil structure, and soil microbial biomass carbon (SMB). Seven N treatments were applied to wheat, but for the purpose of this study we chose a subset of three N treatments (0, 150 and 300 kg N ha⁻¹) for measurements. Maize received a uniform application of 150 kg N ha⁻¹ each year. Soil strength decreased as the amount of crop residues applied for each tillage-straw treatment increased. Permanent beds-straw burned treatment had the highest soil strength and CTB-straw incorporated the lowest. The largest soil aggregate fractionation, evaluated with a fractal dimension parameter (D), corresponded to PB-straw burned treatment and the lowest to PB-straw retained treatment. SMB was greater at 0–7 cm than at 7–15 cm depth. As the amount of crop residues increased in each tillage PB-straw treatment, the SMB generally increased. The largest amount of SMB occurred most often on either CTB-straw incorporated or PB-straw retained and the lowest in PB-straw burned treatment. The practice of retaining crop residues as stubble should be adopted in the Yaqui valley since changes resulting from burning crop residues showed the tendency to decrease productivity and soil quality as shown by increased soil strength and soil fractionation, and reduced SMB.     

Thermal structure and dynamics of Saturn's northern springtime disturbance

Saturn's slow seasonal evolution was disrupted in 2010-2011 by the eruption of a bright storm in its northern spring hemisphere. Thermal infrared spectroscopy showed that within a month, the resulting planetary-scale disturbance had generated intense perturbations of atmospheric temperatures, winds, and composition between 20° and 50°N over an entire hemisphere (140,000 kilometers). The tropospheric storm cell produced effects that penetrated hundreds of kilometers into Saturn's stratosphere (to the 1-millibar region). Stratospheric subsidence at the edges of the disturbance produced "beacons" of infrared emission and longitudinal temperature contrasts of 16 kelvin. The disturbance substantially altered atmospheric circulation, transporting material vertically over great distances, modifying stratospheric zonal jets, exciting wave activity and turbulence, and generating a new cold anticyclonic oval in the center of the disturbance at 41°N.     

Exploring remotely sensed technologies for monitoring wheat potassium and phosphorus using field spectroscopy

Given the importance of potassium (K) and phosphorus (P) contents to wheat yield and grain quality, and the very little experience that has been gained on nutritional monitoring of other than nitrogen using remotely sensed technologies, a study was undertaken to explore the possibility of identifying these mineral stresses using spectral data. Canopy spectra and biophysical data were collected from commercial and experimental fields in India and Israel. Traditional and newly developed vegetation indices, together with Partial Least Squares (PLS) regression models, were calculated in order to predict potassium and phosphorus contents from the wheat canopy spectral data. Results show that the application of PLS and specific narrow bands vegetation indices reached significant levels of accuracy in the retrieval of K and P levels, in comparison to traditional broad band indices. Additionally, it was observed that a significant improvement is obtained when the mineral total content is considered instead of the relative content. Therefore it was suggested that the biomass should also be retrieved from the spectral data. Finally, as very different crop conditions were included in this study, it was possible to confirm that the level of accuracy in the retrieval of K and P levels is related to the quality and variability of the data used for calibrating the models.     

Synthesis of oligosaccharides derived from lactulose and pectinex ultra SP-L

The beta-galactosidase activity of the commercial enzymatic preparation Pectinex Ultra SP-L derived from Aspergillus aculeatus has been used to hydrolyze and transgalactosylate the prebiotic carbohydrate lactulose. During this reaction, new oligosaccharides derived from lactulose have been detected by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The presence of the trisaccharide 6'-galactosyl-lactulose, the major compound formed, has been confirmed by NMR. In addition, disaccharides and other oligosaccharides with higher retention times have been also detected. The effect of transgalactosylation conditions such as time, temperature, pH, and initial lactulose and enzyme concentrations, as well as product inhibition on oligosaccharide synthesis, has been studied. The optimal conditions for the formation of tri and higher oligosaccharides were 60 degrees C, pH 6.5, 450 g/L lactulose, 16 units/mL of enzyme, and 7 h of reaction. Selective formation of disaccharides was achieved under the same conditions with the exception of pH (4.5). The present work provides additional knowledge on the synthesis of new oligosaccharides with potential prebiotic properties.     

A spectral index to monitor the head-emergence of wheat in semi-arid conditions

Harvesting wheat (Triticium aestivum L.) for forage or leaving it for grain is the main decision uncertainty growers face in semi-arid regions during mid-season. To facilitate decision-making, a decision support system (DSS) has recently been proposed that requires information about crop water and nutritional status during spike emergence. Though remote sensing has been used to provide site-specific crop status information, a spectral vegetation index is needed to ensure that the information has been acquired during spike emergence. The objective of this study was to propose a spectral index sensitive to spike emergence and validate its suitability across different commercial farm fields by using ground spectral measurements and multispectral satellite imagery. To develop the index, controlled experiments with commonly grown wheat varieties were conducted during the 2004/2005 and 2005/2006 growing season in the agricultural area of the northern Negev desert of Israel. The experiments showed that spike emergence correlated most strongly (r = 0.7, p < 0.05) with spectral changes near the 1.2 μm water absorption feature in contrast to the band at 1.1 μm which appeared to be only weakly correlated. Thus, the spike emergence sensitive band at 1.2 μm has been combined with the insensitive band at 1.1 μm as reference to form the ratio-based normalized heading index (NHI). Experimental data were then used to establish an index threshold that helps separate data acquired before and after spike emergence. The proposed NHI was able to identify spike emergence with a classification accuracy varying between 53 and 83%. Accuracy was influenced by season, and whether narrow or broad spectral bands were used. Validation of the index in commercial farm fields in Israel and the United States showed that the classification accuracy was similar for ground spectral measurements and the advanced land imager (ALI) satellite imagery. These results suggest that the NHI is suited for identifying the onset of heading throughout wheat-growing areas without the need for characterizing seasonal trends.