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Miranda M.P.D.,Fundo de Defesa da Citricultura | Villada E.S.,Rijk Zwaan Iberica | Lopes S.A.,Fundo de Defesa da Citricultura | Fereres A.,Institute Ciencias Agrarias ICA CSIC | Lopes J.R.S.,University of Sao Paulo
Annals of the Entomological Society of America | Year: 2013

Xylem colonization by Xylello fastidiosa promotes physiological, biochemical, and morphological alterations in citrus plants causing citrus variegated chlorosis (CVC) disease, which might influence the feeding behavior of vectors of this bacterial pathogen and its spread in citrus groves. By using the electrical penetration graph technique, we compared the numbers and durations of stylet penetration activities by adults of the sharpshooter vector Bucephalogonia xanthophis (Berg) (Hemiptera: Cicadellidae) on healthy and X. fastidiosa-infected sweet orange seedlings (Citrus sinensis (L.) Osbeck, cv. Pera). Infected plants were either symptomatic, exhibiting the typical CVC, symptoms or totally asymptomatic. The mean time needed to contact xylem and start xylem sap ingestion after the onset of the first probe was similar among treatments. However, the average time elapsed between the onset of the first probe and the beginning of sustained xylem ingestion (>5 min) was longer on plants with CVC symptoms than on infected asymptomatic or healthy plants. In addition, the length of time spent in ingestion activities was much shorter on symptomatic plants. Our results showed that CVC symptomatic citrus plants were a less acceptable host than uninfected or asymptomatic X. fastidiosa-infected plants. Furthermore, our results support the hypothesis that symptomless infected citrus trees may be more important as sources for CVC spread than severely diseased ones. © 2013 Entomological Society of America.


Gonzalez-Prieto S.,CSIC - National Institute of Agrobiological Sciences | Diaz-Ravina M.,CSIC - National Institute of Agrobiological Sciences | Martin A.,CSIC - National Institute of Agrobiological Sciences | Lopez-Fando C.,Institute Ciencias Agrarias ICA CSIC
Soil and Tillage Research | Year: 2013

Long-term agricultural management may change soil C sequestration and alter soil C and N dynamics. The objective of this study was to investigate the impact of several tillage regimes with different intensity on C and N stocks in a Calcic Haploxeralf with a leguminous/cereal rotation under semiarid conditions after 15, 18 and 21 years of management. Seven chemical and biochemical properties (total C, total N, δ 13C, δ 15N, FDA hydrolysis, β-glucosidase and urease activities) were measured in a soil (0-5cm, 5-10cm, 10-20cm, 20-30cm) under the following agricultural management: fallow (F), no-tillage (NT), zone-tillage subsoiling with a paraplow (ZT), conventional tillage with mouldboard plow (CT), minimum tillage with chisel plow after NT (MTN) or CT (MTC). The results showed that soil reached a steady state of organic matter sequestration 15 years after starting the experiment and that C and N stocks varied greatly with agricultural management, particularly in the top 0-10cm, and followed the order: F≈NT≈ZT>MTN≈MTC>CT. Fallow and less intensively cultivated soils (NT, ZT) exhibited strong vertical gradients of most properties analyzed (total C, total N, FDA hydrolysis, urease and β-glucosidase activities) with values decreasing with depth, followed by minimum tillage treatments (MTN, MTC) whereas similar values along soil profile were observed in CT treatment. No significant differences in soil δ 13C values were detected among plots with different land use or tillage systems; however, the δ 15N values suggested that, although tillage system did not affect significantly N-cycling processes, a change from "open" to "closed" N cycling occurred when cultivated soils were set aside. © 2013.


Ramirez-Bahena M.-H.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | Ramirez-Bahena M.-H.,University of Salamanca | Flores-Felix J.D.,University of Salamanca | Cuesta M.J.,CSIC - Institute of Natural Resources and Agriculture Biology of Salamanca | And 9 more authors.
Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology | Year: 2015

A bacterial strain designated A4STR04T was isolated from the inner root tissue of potatoes in Spain. Phylogenetic analysis based on the 16S rRNA gene sequence placed the isolate into the genus Fontibacillus, being most closely related to Fontibacillus panacisegetis KCTC 13564T with 99 % identity. The isolate was observed to form Gram-positive, motile and sporulating rods. The catalase test was found to be negative and oxidase positive. Nitrate was found to be reduced to nitrite. β-Galactosidase and caseinase were observed to be produced but the production of gelatinase, urease, arginine dehydrolase, ornithine and lysine decarboxylase was negative. Aesculin hydrolysis was found to be positive and acetoin production was negative. Growth was found to be supported by many carbohydrates and organic acids as carbon source. MK-7 was the only menaquinone detected and the major fatty acid (61.5 %) was identified as anteiso-C15:0, as occurs in the other species of genus Fontibacillus. The strain A4STR04T was found to display a complex lipid profile consisting of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, a glycolipid, two phospholipids, a lipid and two aminophospholipids. Mesodiaminopimelic acid was detected in the peptidoglycan. The G+C content was determined to be 50.5 mol% (Tm). Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain A4STR04T (=LMG 28458 T = CECT 8693T) should be classified as representing a novel species of genus Fontibacillus, for which the name Fontibacillus solani sp. nov. is proposed. © 2015, Springer International Publishing Switzerland.


Anbalagan C.,University of Nottingham | Lafayette I.,University of Nottingham | Antoniou-Kourounioti M.,University of Nottingham | Gutierrez C.,Institute Ciencias Agrarias ICA CSIC | And 3 more authors.
Ecotoxicology | Year: 2013

As a free-living nematode, C. elegans is exposed to various pesticides used in agriculture, as well as to persistent organic residues which may contaminate the soil for long periods. Following on from our previous study of metal effects on 24 GFP-reporter strains representing four different stress-response pathways in C. elegans (Anbalagan et al. Ecotoxicology 21:439-455, 2012), we now present parallel data on the responses of these same strains to several commonly used pesticides. Some of these, like dichlorvos, induced multiple stress genes in a concentration-dependent manner. Unusually, endosulfan induced only one gene (cyp-34A9) to very high levels (8-10-fold) even at the lowest test concentration, with a clear plateau at higher doses. Other pesticides, like diuron, did not alter reporter gene expression detectably even at the highest test concentration attainable, while others (such as glyphosate) did so only at very high concentrations. We have also used five responsive GFP reporters to investigate the toxicity of soil pore water from two agricultural sites in south-east Spain, designated P74 (used for cauliflower production, but significantly metal contaminated) and P73 (used for growing lettuce, but with only background levels of metals). Both soil pore water samples induced all five test genes to varying extents, yet artificial mixtures containing all major metals present had essentially no effect on these same transgenes. Soluble organic contaminants present in the pore water were extracted with acetone and dichloromethane, then after evaporation of the solvents, the organic residues were redissolved in ultrapure water to reconstitute the soluble organic components of the original soil pore water. These organic extracts induced transgene expression at similar or higher levels than the original pore water. Addition of the corresponding metal mixtures had either no effect, or reduced transgene expression towards the levels seen with soil pore water only. We conclude that the main toxicants present in these soil pore water samples are organic rather than metallic in nature. Organic extracts from a control standard soil (Lufa 2.2) had negligible effects on expression of these genes, and similarly several pesticides had little effect on the expression of a constitutive myo-3::GFP transgene. Both the P73 and P74 sites have been treated regularly with (undisclosed) pesticides, as permitted under EU regulations, though other (e.g. industrial) organic residues may also be present. © 2012 Springer Science+Business Media New York.


Amoros-Jimenez R.,University of Alicante | Pineda A.,Wageningen University | Fereres A.,Institute Ciencias Agrarias ICA CSIC | Marcos-Garcia M.A.,University of Alicante
BioControl | Year: 2014

Provision of additional floral resources in the crop is a successful strategy of conservation biological control for attracting several natural enemies including predatory syrphids. However, the selection of flower species is mainly based on visiting preferences, paying little attention to the link between preference and performance. In this study, we assess the influence of feeding on flowers of two insectary plants (sweet alyssum and coriander) and flowers of a crop species (sweet pepper) on performance of the parental and first generation of the syrphid Sphaerophoria rueppellii (Wiedemann) (Diptera: Syrphidae). We found that floral preference of the adults was linked to developmental performance of their offspring. Sweet alyssum was the flower most frequently visited by syrphid adults, enhancing adult body size and egg-to adult survival of the F1 generation. © 2014 International Organization for Biological Control (IOBC).


PubMed | Institute Ciencias Agrarias ICA CSIC and Technical University of Madrid
Type: Evaluation Studies | Journal: Pest management science | Year: 2015

Long-lasting insecticide-treated nets (LLITNs) constitute a novel alternative that combines physical and chemical tactics to prevent insect access and the spread of insect-transmitted plant viruses in protected enclosures. This approach is based on a slow-release insecticide-treated net with large hole sizes that allow improved ventilation of greenhouses. The efficacy of a wide range of LLITNs was tested under laboratory conditions against Myzus persicae, Aphis gossypii and Bemisia tabaci. Two nets were selected for field tests under a high insect infestation pressure in the presence of plants infected with Cucumber mosaic virus and Cucurbit aphid-borne yellows virus. The efficacy of Aphidius colemani, a parasitoid commonly used for biological control of aphids, was studied in parallel field experiments.LLITNs produced high mortality of aphids, although their efficacy decreased over time with sun exposure. Certain nets excluded whiteflies under laboratory conditions; however, they failed in the field. Nets effectively blocked the invasion of aphids and reduced the incidence of viruses in the field. The parasitoid A. colemani was compatible with LLITNs.LLITNs of appropriate mesh size can become a very valuable tool in combination with biocontrol agents for additional protection against insect vectors of plant viruses under IPM programmes.


Anbalagan C.,University of Nottingham | Lafayette I.,University of Nottingham | Antoniou-Kourounioti M.,University of Nottingham | Haque M.,University of Nottingham | And 6 more authors.
Ecotoxicology | Year: 2012

Caenorhabditis elegans strains carrying stressreporter green fluorescent protein transgenes were used to explore patterns of response to metals. Multiple stress pathways were induced at high doses by most metals tested, including members of the heat shock, oxidative stress, metallothionein (mtl) and xenobiotic response gene families. A mathematical model (to be published separately) of the gene regulatory circuit controlling mtl production predicted that chemically similar divalent metals (classic inducers) should show additive effects on mtl gene induction, whereas chemically dissimilar metals should show interference. These predictions were verified experimentally; thus cadmium and mercury showed additive effects, whereas ferric iron (a weak inducer) significantly reduced the effect of mercury. We applied a similar battery of tests to diluted samples of soil pore water extracted centrifugally after mixing 20% w/w ultrapure water with air-dried soil from an abandoned lead/zinc mine in the Murcia region of Spain. In addition, metal contents of both soil and soil pore water were determined by ICP-MS, and simplified mixtures of soluble metal salts were tested at equivalent final concentrations. The effects of extracted soil pore water (after tenfold dilution) were closely mimicked by mixtures of its principal component ions, and even by the single most prevalent contaminant (zinc) alone, though other metals modulated its effects both positively and negatively. In general, mixtures containing similar (divalent) metal ions exhibited mainly additive effects, whereas admixture of dissimilar (e.g. trivalent) ions often resulted in interference, reducing overall levels of stress-gene induction. These findings were also consistent with model predictions. © 2011 Springer Science+Business Media, LLC.


Dader B.,Institute Ciencias Agrarias ICA CSIC | Plaza M.,Institute Ciencias Agrarias ICA CSIC | Fereres A.,Institute Ciencias Agrarias ICA CSIC | Moreno A.,Institute Ciencias Agrarias ICA CSIC
Annals of Applied Biology | Year: 2015

Ultraviolet (UV) radiation, particularly in the UV-A + B range (280-400 nm) is a fraction of the solar spectrum that regulates almost every aspect of insect behaviour, including orientation towards hosts, alighting, arrestment and feeding behaviour. To study the role of UV radiation on the flight activity of five insect species of agricultural importance (pests Myzus persicae, Bemisia tabaci and Tuta absoluta, and natural enemies Aphidius colemani and Sphaerophoria rueppellii), one-chamber tunnels were covered with six cladding materials with different light transmittance properties ranging from 2% to 83% UV and 54% to 85% photosynthetically active radiation (PAR). Inside each tunnel, insects were released from tubes placed in a platform suspended from the ceiling. Specific targets varying with insect species were placed at different distances from the platform. Evaluation parameters were designed for each insect and tested separately. The ability of insects to leave the platform was assessed, as well as the number of captures, eggs or mummies in each target, either sticky traps or plants. Our results suggest differences in flight activity among insect species and UV-blocking nets. The UV-opaque film drastically prevented aphids, and whiteflies from flying outside the tubes whereas T. absoluta, syrphids and parasitoids were not affected. Aphid flight behaviour was affected by the UV-opaque film compared to the other nets, especially in the furthest target of the tunnel. Fewer aphids reached distant traps under UV-absorbing nets, and significantly more aphids could fly to the end of tunnels covered with non-UV-blocking materials. Orientation of B. tabaci and T. absoluta was also negatively affected by the UV-opaque film although in a different trend. Unlike aphids, differences in B. tabaci captures were mainly found in the closest targets. UV transmittance did not have any effects on parasitoids, and S. rueppellii, implying cues other than visual for these insects under our experimental conditions. Further effects of photoselective enclosures on greenhouse pests and their natural enemies are discussed. © 2015 Association of Applied Biologists.


Rincon A.,Institute Ciencias Agrarias ICA CSIC
Mycorrhiza | Year: 2014

Environmental disturbances define the diversity and assemblage of species, affecting the functioning of ecosystems. Fire is a major disturbance of Mediterranean pine forests. Pines are highly dependent on the ectomycorrhizal (EM) fungal symbiosis, which is critical for tree recruitment under primary succession. To determine the effects of time since fire on the structure and recovery of EM fungal communities, we surveyed the young Pinus pinaster regenerate in three sites differing in the elapsed time after the last fire event. Pine roots were collected, and EM fungi characterized by sequencing the internal transcribed spacer (ITS) and the large subunit (LSU) regions of the nuclear ribosomal (nr)-DNA. The effects of the elapsed time after fire on the EM community structure (richness, presence/absence of fungi, phylogenetic diversity) and on soil properties were analysed.Fungal richness decreased with the elapsed time since the fire; although, the phylogenetic diversity of the EM community increased. Soil properties were different depending on the elapsed time after fire and particularly, the organic matter, carbon-to-nitrogen (C/N) ratio, nitrogen and iron significantly correlated with the assemblage of fungal species. Ascomycetes, particularly Tuberaceae and Pezizales, were significantly over-represented on saplings in the burned site. On seedlings, a significant over-representation of Rhizopogonaceae and Atheliaceae was observed in the most recently burned site, while other fungi (i.e. Cortinariaceae) were significantly under-represented. Our results are consistent with the hypothesis that fire can act as a selective agent by printing a phylogenetic signal on the EM fungal communities associated with naturally regenerated pines, pointing out to some groups as potential fire-adapted fungi.


Arauzo M.,Institute Ciencias Agrarias ICA CSIC | Valladolid M.,CSIC - National Museum of Natural Sciences | Martinez-Bastida J.J.,Institute Ciencias Agrarias ICA CSIC
Journal of Hydrology | Year: 2011

Reducing nitrate pollution from diffuse agricultural sources is the major environmental challenge in the two adjacent catchments of the Oja-Tirón and Zamaca rivers (La Rioja and Castilla y León, northern Spain). For this reason, part of their territory was designated a Nitrate Vulnerable Zone (NVZ) according to the Nitrates Directive. The Oja Alluvial Aquifer, the Tirón Alluvial Aquifer and their associated rivers are particularly vulnerable to nitrogen pollution due to the shallow water table, the high permeability of alluvial deposits, interconnections between the alluvial aquifers and surface waters and pressures from agriculture. To this end, nine sampling campaigns, organised on a semi-annual basis and focused on the rivers and alluvial aquifers of the two catchments, were carried out from April 2005 to April 2009. The main objectives of the study were: (1) to investigate the chemical forms of nitrogen in river-alluvial aquifer systems of the Oja-Tirón and Zamaca catchments, (2) to improve our understanding of the spatio-temporal patterns of nitrogen distribution in the alluvial aquifers and associated rivers by integrating hydrochemical data and hydrogeological and environmental parameters, (3) to estimate the amount of nitrogen exported from the rivers and alluvial aquifers to the River Ebro, and (4) to evaluate the suitability of the current method of designating NVZs in the area.High groundwater flow velocities in the upper alluvial zones favoured the advective transport of nitrate and generated a dilution effect. In these areas, inter-annual variations in nitrate concentrations were observed related to precipitation and N-input from agriculture. However, low flow velocities favoured processes of accumulation in the lower alluvial zones. Our results demonstrated that the entire alluvial surface was highly vulnerable, according to dynamics of the nitrogen in the river-alluvial aquifer systems being studied. The amount of nitrogen exported from these river-alluvial aquifer systems to the River Ebro was estimated at 2.4±0.2ktyear-1. Findings from this investigation highlight the need to include the alluvial area corresponding to the Tirón aquifer as a NVZ, particularly as the Tirón sub-catchment provides more than half of the nitrogen exported from the River Tirón to the River Ebro. Based in these results, at least the entire alluvial surface in the study area should be considered a NVZ in order to address the recovery of water quality. © 2011 Elsevier B.V..

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