Ecdysteroid receptor docking suggests that dibenzoylhydrazine-based insecticides are devoid of any deleterious effect on the parasitic wasp Psyttalia concolor (Hym. Braconidae)     

Bengochea P  Christiaens O  Amor F  Viñuela E  Rougé P  Medina P  Smagghe G 《Pest management science》2012,68(7):976-985

BACKGROUND: The moulting accelerating compounds (MACs) or ecdysteroid agonists represent a selective group of insecticides acting upon binding to the ecdysteroid receptor (EcR) and leading to lethal premature moulting in larval stages and aborted reproduction in adults. Psyttalia concolor Szèpl. is a useful parasitic wasp attacking important tephritid pests such as the medfly and olive fruit fly. RESULTS: Contact and oral exposure in the laboratory of female parasitic wasps to the dibenzoylhydrazine‐based methoxyfenozide, tebufenozide and RH‐5849 did not provoke negative effects. No mortality and no reduction in beneficial capacity were observed. The ligand‐binding domain (LBD) of the EcR of P. concolor was sequenced, and a homology protein model was constructed which confirmed a cavity structure with 12 α‐helices, harbouring the natural insect moulting hormone 20‐hydroxyecdysone. However, a steric clash occurred for the MAC insecticides owing to a restricted extent of the ligand‐binding cavity of the PcLBD‐EcR, while they did dock well in that of susceptible insects. CONCLUSIONS: The insect toxicity assays demonstrated that MACs are selective for P. concolor. The modelling/docking experiments are indications that these insecticides do not bind with the LBD‐EcR of P. concolor and support the theory that they show no biological effects in the parasitic wasp. These data may help in explaining the compatible use of MACs together with parasitic wasps in IPM programmes. Copyright © 2012 Society of Chemical Industry  相似文献   

Gene expression analysis of chilling requirements for flower bud break in peach     

Carmen Leida  José F. Romeu  Jesús García‐Brunton  Gabino Ríos  María L. Badenes 《Plant Breeding》2012,131(2):329-334

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Improved <Emphasis Type="Italic">S</Emphasis>-genotyping and new incompatibility groups in Japanese plum     

María E. Guerra  Margarita López-Corrales  Ana Wünsch 《Euphytica》2012,186(2):445-452

The selection of cross-compatible cultivars is essential to ensure fruit set in self-incompatible species like Japanese plum and thus the S-genotype must be determined in order to establish incompatibility groups. In this study an improved Japanese plum S-genotyping method, based in polymerase chain reaction and capillary electrophoresis detection of intron polymorphisms of S-locus genes, S-RNase and SFB, has been assayed and validated in a wide sample of cultivars. This method allows a more precise determination of amplified fragment sizes and therefore a better differentiation of self-incompatibility alleles. The assayed methodology was proven effective in the detection of 13 different S-alleles of S-RNases and SFBs and was used to S-genotype 105 Japanese plum cultivars, 32 of which are described by first time in this work. Analysed cultivars were assigned into 11 incompatibility groups and two new incompatibility groups (XX and XXI) were identified, increasing to 21 the number of incompatibility groups described in this crop.  相似文献   

Detection of bacterial wilt infection caused by Ralstonia solanacearum in potato (Solanum tuberosum L.) through multifractal analysis applied to remotely sensed data     

Perla Chávez  Christian Yarlequé  Hildo Loayza  Víctor Mares  Paola Hancco  Sylvie Priou  María del Pilar Márquez  Adolfo Posadas  Percy Zorogastúa  Jaume Flexas  Roberto Quiroz 《Precision Agriculture》2012,13(2):236-255

Potato bacterial wilt, caused by the bacterium Ralstonia solanacearum race 3 biovar 2 (R3bv2), affects potato production in several regions in the world. The disease becomes visually detectable when extensive damage to the crop has already occurred. Two greenhouse experiments were conducted to test the capability of a remote sensing diagnostic method supported by multispectral and multifractal analyses of the light reflectance signal, to detect physiological and morphological changes in plants caused by the infection. The analysis was carried out using the Wavelet Transform Modulus Maxima (WTMM) combined with the Multifractal (MF) analysis to assess the variability of high-resolution temporal and spatial signals and the conservative properties of the processes across temporal and spatial scales. The multispectral signal, enhanced by multifractal analysis, detected both symptomatic and latently infected plants, matching the results of ELISA laboratory assessment in 100 and 82%, respectively. Although the multispectral method provided no earlier detection than the visual assessment on symptomatic plants, the former was able to detect asymptomatic latent infection, showing a great potential as a monitoring tool for the control of bacterial wilt in potato crops. Applied to precision agriculture, this capability of the remote sensing diagnostic methodology would provide a more efficient control of the disease through an early and full spatial assessment of the health status of the crop and the prevention of spreading the disease.  相似文献   

Spatial variability in grape yield and quality influenced by soil and crop nutrition characteristics     

J. Arnó  J. R. Rosell  R. Blanco  M. C. Ramos  J. A. Martínez-Casasnovas 《Precision Agriculture》2012,13(3):393-410

Knowledge of spatial variability of soil fertility and plant nutrition is critical for planning and implementing site-specific vineyard management. To better understand the key drivers behind vineyard variability, yield mapping from 2002 to 2005 and 2007 (the monitor broke down in 2006) was used to identify zones of different productive potential in a Pinot Noir field located in Raimat (Lleida, Spain). Simultaneously, the vineyard field was sampled in 2002, 2003 and 2007, applying three different schemes (depending on the number of target vines in different grape yield zones). The sampling carried out in 2002, which involved different soil, topographic and crop properties (mineral contents in petiole), made it possible to evaluate the influence of these parameters on the grape yield variability. The zones of lowest yield coincided with locations in which the nutritional status of the crop exhibited the lowest values, particularly with respect to petiole contents of calcium and manganese. Sampling systems adopted in 2003 and 2007 (grape quality and soil attributes) confirmed the inverse spatial correlation between grape yield and some grape quality parameters and, more importantly, showed that the percentage of soil carbonates had a great influence on grape quality probably due to the reduced availability of manganese in calcareous soils. Site-specific vineyard management could therefore be considered using two different strategies: variable-rate application of foliar fertilizers to increase the yield in areas with low production and also foliar or soil fertilizers to improve the quality specifications in some areas.  相似文献   

Participative site-specific agriculture analysis for smallholders   总被引：1，自引：0，他引：1  

Pau Aragó Galindo  Carlos Granell  Paulo Guilherme Molin  Joaquín Huerta Guijarro 《Precision Agriculture》2012,13(5):594-610

Site-specific agriculture has been adopted in a high-tech context using, for instance, in situ sensors, satellite images for remote sensing analysis, and some other technological devices. However, farmers and smallholders without the economic resources and required knowledge to use and to access the latest technology seem to find an impediment to precision agricultural practices. This article discusses the possibility of adopting precision agriculture (PA) principles for site-specific management but in a low technology context for such farmers. The proposed methodology to support PA combines low technology dependency and a participatory approach by involving smallholders, farmers and experts. The case studies demonstrate how the interplay of low technology and a participative approach may be suitable for smallholders for site-specific agriculture analysis.  相似文献   

Understanding the errors in input prescription maps based on high spatial resolution remote sensing images     

David Gómez-Candón  Francisca López-Granados  Juan J. Caballero-Novella  José M. Pe?a-Barragán  Luis García-Torres 《Precision Agriculture》2012,13(5):581-593

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Probing the ultimate limits of plasmonic enhancement     

C Ciracì  RT Hill  JJ Mock  Y Urzhumov  AI Fernández-Domínguez  SA Maier  JB Pendry  A Chilkoti  DR Smith 《Science (New York, N.Y.)》2012,337(6098):1072-1074

Metals support surface plasmons at optical wavelengths and have the ability to localize light to subwavelength regions. The field enhancements that occur in these regions set the ultimate limitations on a wide range of nonlinear and quantum optical phenomena. We found that the dominant limiting factor is not the resistive loss of the metal, but rather the intrinsic nonlocality of its dielectric response. A semiclassical model of the electronic response of a metal places strict bounds on the ultimate field enhancement. To demonstrate the accuracy of this model, we studied optical scattering from gold nanoparticles spaced a few angstroms from a gold film. The bounds derived from the models and experiments impose limitations on all nanophotonic systems.  相似文献   

Collapse of Classic Maya civilization related to modest reduction in precipitation   总被引：2，自引：0，他引：2  

Medina-Elizalde M  Rohling EJ 《Science (New York, N.Y.)》2012,335(6071):956-959

The disintegration of the Classic Maya civilization in the Yucatán Peninsula and Central America was a complex process that occurred over an approximately 200-year interval and involved a catastrophic depopulation of the region. Although it is well established that the civilization collapse coincided with widespread episodes of drought, their nature and severity remain enigmatic. We present a quantitative analysis that offers a coherent interpretation of four of the most detailed paleoclimate records of the event. We conclude that the droughts occurring during the disintegration of the Maya civilization represented up to a 40% reduction in annual precipitation, probably due to a reduction in summer season tropical storm frequency and intensity.  相似文献   

Direct mapping of nuclear shell effects in the heaviest elements     

E Minaya Ramirez  D Ackermann  K Blaum  M Block  C Droese  ChE Düllmann  M Dworschak  M Eibach  S Eliseev  E Haettner  F Herfurth  FP Heßberger  S Hofmann  J Ketelaer  G Marx  M Mazzocco  D Nesterenko  YN Novikov  WR Plaß  D Rodríguez  C Scheidenberger  L Schweikhard  PG Thirolf  C Weber 《Science (New York, N.Y.)》2012,337(6099):1207-1210

Quantum-mechanical shell effects are expected to strongly enhance nuclear binding on an "island of stability" of superheavy elements. The predicted center at proton number Z = 114, 120, or 126 and neutron number N = 184 has been substantiated by the recent synthesis of new elements up to Z = 118. However, the location of the center and the extension of the island of stability remain vague. High-precision mass spectrometry allows the direct measurement of nuclear binding energies and thus the determination of the strength of shell effects. Here, we present such measurements for nobelium and lawrencium isotopes, which also pin down the deformed shell gap at N = 152.  相似文献