Virus-vector nematodes in cereals and fruit crops in Spain

8 páginas, tabla estadistica y mapasStudies on nepoviruses and tobraviruses, and their relationships with their associated vector nematodes, are scarce in Spain. However, virus disease symptoms have often been detected and their nematode vectors are widespread in Peninsular Spain. Nepovirus vector nematodes (Longidorus attenuatus, L. coespiticola, L. elongatus, L. macrosoma, Xiphinema coxi, X. diversicaudatum, X. index, X. italiae, X. pseudocoxi and X. vuittenezi) have been found associated with fruit and cereal crops. AH are also widespread in other crops and uncultivated areas, together with X. rivesi, which has not yet been found associated with fruit and cereal crops in Spain. Tobravirus vectors have been less studied in Spain. Ofthe five recorded species, Paratrichodorus minor and Trichodorus primitivus are present on maize and wheat respectively. The geographical and host distribution ofthese nematodes are given and their ecological characteristics are discussed.Peer reviewe

Estrategias en el control y manejo de nematodos fitoparasitarios

7 páginas y 4 figurasLos nematodos fitoparasitarios constituyen un grupo de gran impacto en cualquier agrosistema por su acción patogénica sobre la mayoría de las plantas cultivadas. Las pérdidas de cosecha anuales estimadas debidas a nematodos fitoparásitos en la producción agrícola mundial se aproxima al 11 % y en términos absolutos las perdidas económicas anuales se calculan en torno a los 100 billones de dólares. Cualquier estrategia de control debe tener en cuenta sus características taxonómicas y biológicas e interacción específica con el cultivo. Dentro de los métodos de control, la aplicación de productos químicos es el más utilizado, ya que provoca la drástica reducción de la densidad de población del nematodo y minimiza las pérdidas a corto plazo. Sin embargo está demostrado que la aplicación sistemática de compuestos químicos con actividad nematicida tiene un riesgo potencial de contaminación medioambiental elevado y pueden llegar a ser muy tóxicos para productores y consumidores. Por ello es fundamental el desarrollo de estrategias de manejo cuyo objetivo no sea la erradicación sino la manipulación del nematodo patógeno hasta conseguir una reducción de la densidad de población por debajo del umbral de daño al cultivo, mediante el uso integrado de diversos métodos de control (técnicas culturales, solarización, control biológico, variedades resistentes e incluso aplicaciones específicas de nematicidas) durante un cierto periodo de tiempo. El reconocimiento de objetivos a largo plazo contribuirá a mantener la calidad ambiental y a la disminución de las perdidas económicas sufridas por los productores, optimizando el beneficio en un largo periodo de tiempo.CSIC - Centro de Ciencias Medioambientales (CCMA)Peer reviewe

Population dynamics of Globodera pallid (Nematoda: Heteroderidae) on two potato cultivars in natural field conditions in Balearic Islands, Spain

8 páginas, 2 figuras y 1 tabla estadística[EN] Globodera pallida is a serious economic pest in worldwide planting of potatoes due to the severe crop losses they can cause. This study aimed to determine the relationship between soil temperature [degree-day accumulation (DD4)] and population development of G. pallida under the agroecological conditions of the Balearic Islands, Spain. Population changes were studied in ‘Marfona’ and ‘Maris Peer’ potato cultivars for three growing seasons. Differences in the pattern of occurrence of nematode life stages on the two potato cultivars were observed. In Maris Peer trials, secondstage juveniles (J2) hatching occurred about one month after planting (29 and 35 days), J2 root invasion at 57-56 days, and females in roots at 77 days with 540 DD4. In Marfona trials, these nematode stages occurred at 18-31days, 45-52 days and 59-73 days, the last one with 400 DD4. Hence, in Mallorca, G. pallida populations require at least 100 DD4 more in Maris Peer early potato than in the Marfona to reach the adult stage. Senescence in Maris Peer crops happened before most of the females have become brown cyst, suggesting that in this area the Maris Peer early cultivar could exert trap crop effects. The Marfona crop yield obtained at highest level of nematode infestation may indicate that Marfona seems to be more tolerant to G. pallida than Maris Peer. The results contribute to the knowledge of thermal time requirements of G. pallida populations under Mediterranean environmental conditions and can be a valuable tool to develop potato cyst nematode control strategies.[ES] Se estudia la dinámica poblacional de Globodera pallida y su relación con las temperaturas del suelo [grados acumulados (DD4)] y con la fenología de la planta hospedadora, en los cultivares de patata ‘Marfona’ y ‘Maris Peer’, en las Islas Baleares, España. Se observaron diferencias entre ambos cultivares respecto al patrón de aparición de los estadios vitales del nematodo. En Maris Peer, la eclosión de los juveniles de 2ª edad (J2) se produjo un mes después de la siembra (a los 29 y 35 días), la invasión radical de los J2 57-56 días después, y la aparición de las hembras en las raíces 77 días después, con 540 DD4. En Marfona, la aparición de los distintos estadios tuvo lugar a los 18-31 días, a 45-52 días y a 59-73 días después de la siembra respectivamente, este último con 400 DD4. Por tanto, en Mallorca, G. pallida necesita 100 DD4 más para llegar al estadio adulto en el cultivar Maris Peer que en Marfona. La senescencia del cultivo de Maris Peer se produjo antes de la maduración de los quistes, por lo que en esta región el cultivar de patata temprana Maris Peer podría actuar como cultivo trampa, impidiendo que G. pallida finalice su ciclo biológico. El cultivar Marfona presenta una mayor tolerancia a densidades altas del nematodo que Maris Peer. Los resultados obtenidos contribuyen al conocimiento de los requerimientos termales de las poblaciones de G. pallida en agrosistemas mediterráneos y pueden tener una importancia fundamental para el diseño de estrategias de control.Spanish National Institute for Agricultural and Food Research and Technology (INIA) RTA 02-014 Project.Peer reviewe

Fungal endophyte-based Biopesticides

Trabajo presentado en el IX Simposio Internacional de Química de Productos Naturales y sus Aplicaciones, celebrado en Chillán (Chile) del 22 al 25 de noviembre de 2016.Endophytes are microorganisms that live in the intercellular spaces of plant tissues producing bioactive substances that may be involved in the host-endophyte relationship . These endophytes produce bioactive substances that may be involved in the host-endophyte relationship. Therefore, these microorganisms represent a biotechnological source of bioactive metabolites. As part of our ongoing study of the endophyte potential for the development of biotechnological biopesticides , we carried out the screening of endophytes from medicinal plants belonging to the genera Laurus, Mentha, Artemisia and Thymus present in India and Spain. We have also isolated 34 different species of fungal endophytes from the tree Persea indica. This plant is one of the dominant species of the Canarian laurel forest and has been reported as a potential source of insect-control agents . Our study included the endophyte biodiversity (isolation and identification) of these plants species, the antagonism-based primary selection of isolates for microfermentation and the secondary selection based on their micro-extract activity on selected targets including insect pests, (Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi) fungal pathogens and root-knot nematodes (Meloidogyne javanica) to assess their potential as biotechnological biopesticides. In this presentation we will discuss the relative percentage occurrence for each order and the colonization frequency for each fungal species, the antagonistic effects of these isolates against fungal pathogens (Fusarium sp.) and the bioactivity of their microextracts on the target species will be presented. The bio-guided chemical study of selected strains will be presented.Peer Reviewe

New tool for fungal pathogen control

Trabajo presentado en el Seminaire sur les maladies de l´olivier, celebrado en Mequinez (Marruecos) del 4 al 5 de abril de 2017.Peer Reviewe

Botanicals: The future pest/parasite control?

Trabajo presentado en el 2nd International Conference on Pesticidal Plants, celebrado en las Cataratas Victoria (Zimbabue) del 6 al 9 de febrero de 2017.The indiscriminate use of synthetic pesticides has generated environmental and public health problems. In recent years, the use of these products and the number of active ingredients has been limited by very restrictive legislation in the EU and other countries. Therefore, there is a growing need for alternative control agents, including natural products and biocontrol. In this context the Biopesticides Group-CSIC has screened hundreds of botanical species from the Iberian Peninsula, the Canary Islands, Chile and Peru, selected based on biodiversity and ethnobotanical criteria. The ethanolic extracts of these species have been tested against a broad spectrum of targets including crop pests and diseases (insects: Spodoptera littoralis, Leptinotarsa decemlineata, Myzus persicae, Rhopalosiphum padi; phytopathogenic fungi: Fusarium oxysporum, Botrytis cinerea, Alternaria alternate; phytopathogenic nematodes: Meloydogyne javanica), plants (Lactuca sativa, Lolium perenne) and animal ecto-parasites (ticks: Hyalomma lusitanicum), all responsible for significant economic losses in crop and livestock production. Several species of interest have been identified for crop protection and tick control. Standing out above the rest are Artemisia absinthium var. Candial® for fungal, insect and nematode control and Lavandula luisieri for weed and tick control. The bioguided chemical study of these species resulted in the chemical isolation and characterization of their active molecules. Furthermore, both plant extracts have been patented and licensed to small and medium-sized enterprises for the development of new products. In this presentation we will outline the discovery, development and future prospects of the most promising plant species of the research group pipeline.Peer Reviewe

Bioplaguicidas botanicos basados en extractos optimizados de Artemisis absinthium y Lavandula luisieri

Trabajo presentado en el V Congreso Iberoamericano de Productos Naturales, celebrado en Bogotá (Colombia) del 25 al 29 de abril de 2016.La agricultura se enfrenta a graves problemas de plagas y patógenos. En este contexto, el uso excesivo de plaguicidas sintéticos ha provocado el desarrollo de resistencias, contaminación del medio ambiente, toxicidad para organismos beneficiosos y riesgos para la salud humana. Nuestro trabajo pretende contribuir a una protección vegetal más sostenible mediante el desarrollo de bioplaguicidas basado en el uso sostenible de extractos de plantas y residuos de su extracción. Las herramientas de producción de biomasa incluyen la domesticación y cultivo en campo además de cultivo in vitro y aeropónico. Los extractos se obtienen a partir de recursos procedentes de especies seleccionadas de la flora autóctona de la Península Ibérica. Este trabajo se centra en las especies Artemisia absinthium y Lavandula luisieri. Estas especies se han domesticado o están en proceso de domesticación. Se han generado aceites esenciales, hidrolatos, extractos orgánicos (hexánicos, etanólicos)2,3 y extractos de CO2 supercrítico4,5. El cribado de bioactividad de los extractos frente a una serie de dianas seleccionadas (insectos plaga, nematodos fitoparásitos, hongos fitopatógenos y plantas) se ha combinado con la caracterización química de los compuestos bioactivos para identificar los quimiomarcadores de interés (compuestos 1-3 de A. absinthium y compuestos 4 y 5 de L. luisieri). Los extractos optimizados se han patentado y transferido al sector industrial.Proyecto CTQ2012-38219-C03-01Peer Reviewe

Virulence response to the Mi.1 gene of Meloidogyne populations from tomato in greenhouses

9 páginas, 2 figuras y 4 tablas estadísticasIn a comparison of reproductive traits of 29 field populations of Meloidogyne spp. on resistant and susceptible tomatoes, 48% of the populations were virulent against the Mi.1 gene. Virulent populations produced more (P< 0.05) egg masses/plant, eggs/plant, eggs/g root, and showed higher infection frequencies and multiplication rates than the avirulent populations. The fecundity of females did not differ between the resistant and susceptible genotype, and did not change with the virulence status of the populations. On the resistant genotype, the populations collected from the susceptible tomato showed lower (P < 0.05) reproductive traits than those collected from rootstocks followed by those from resistant tomato. Meloidogyne javanica produced more (P < 0.05) egg masses/plant and eggs/g root than Meloidogyne incognita on the resistant genotype. A time course experiment was conducted to determine if root penetration by M. javanica populations with different Mi.1 virulence status is conditioned by the expression of resistance on tomato. Significant differences between populations were observed as early as of 2 days post-inoculation on the susceptible genotype. On the resistant genotype, low juvenile numbers from populations with acquired virulence penetrated the roots up to 4 dpi, but their numbers significantly increased 7 dpi. Juveniles of the natural virulent population followed similar penetration pattern on the resistant and susceptible genotypes. Peroxidases are involved in the oxidative burst typically associated with the hypersensitive response in incompatible hostepathogen interactions. Isoelectrofocusing isozyme analysis revealed an increase in the peroxidase activity on the resistant genotype after inoculation with the avirulent population and to a lesser degree with the populations with acquired virulence in comparison with the natural virulent population.Project AGL2009-13027-CO2-02; AGL2010-17388 MICINN. Project RTA2010-00017-C02-01 INIAPeer reviewe

Genetic relationships and isozyme variability in the Heterodera avenae complex determined by Isoelectrofocusing

10 páginas, 6 figuras y 1 tabla estadísticaIsozyme variability was assessed among the principal species of the cereal cyst nematode complex to complete and enhance the information provided by classical nematode systematics, in order to clarify inter- and intraspecific relationships within this complex. Twenty populations of cereal cyst nematodes (Heterodera avenae, H. filipjevi, H. latipons and H. mani) were compared by means of five different isoenzymatic systems (esterase, malate dehydrogenase, phosphoglucoisomerase, phosphoglucomutase and superoxide dismutase) using isoelectrofocusing (IEF) on the electrophoretic separation. The results are in agreement with previous morphological and biochemical characterizations, which established genetic diversity between the Gotland strain and H. avenae and identified the Gotland strain with H. filipjevi. Populations from Israel, all included in the H. avenae group, exhibited well-defined intraspecific dissimilarity. The highest degree of polymorphism was found in the H. avenae group for all five enzymatic systems studied. The H. mani population was also included in the H. avenae group by these isozyme analyses. Malate dehydrogenase, phosphoglucoisomerase and phosphoglucomutase isozymes, fractionated for the first time by IEF in the cereal cyst nematode complex, displayed a higher level of polymorphism than using conventional electrophoresis. Isoelectric focusing has proved to be a useful tool for detecting genetic diversity within and among species of the cereal cyst nematode complex and for taxonomic purposes.CICYT AGF98-1057-CO4Peer reviewe

Nematicidal effects of endophytic fungus Guignardia sp

Trabajo presentado en Natural Products and Biocontrol Congress, celebrado en Perpignan (France) del 21 al 23 de septiembre de 2016.Root-knot nematodes ( Meloidogyne spp.) are major threats to agriculture worldwide .They are obligate endoparasites that infect a large range of crop plants, leading to considerable economic losses. In the last decades, environmental and human health concerns have steadily reduced the availability of efficient commercial nematicides. Therefore, environmentally friendly substances for effective nematode control are needed to be developed. Endophytes fungi produce biologically active natural products that may be involved in the host-endophyte relationship. Therefore, these microorganisms represent a biotechnological source of bioactive metabolites. As part of our ongoing study of the endophyte biodiversity of the Canarian Laurel Forest, we have obtained an isolate of endophytic fungus Guignardia sp from Perseo indica, one of the dominant Lauraceae tree species reported as a potential source of insect-control agents. This Guignardia sp. endophytic isolate {YCC4) was ferme nted in liquid medium for 20 days. The organic extract was obtained by liquid extraction of culture medium with ethyl acetate. The organic extract (1 µg/µI) showed strong nematicidal in vitro activity against root-knot nematode M. javanica (infective juveniles mortality and long-term egg hatching inhibition effects). Based on bioassay-guided fractionation, three metabolites inducing high nematicidal effects were obtained. Several in vivo tests of organic extract from isolate YCC4 on tomato plants showed strong effects, supressing the infectivity of juveniles and reducing the reproduction index of the nematode population. In conclusion, this study demonstrates that secondary metabolites from endophytic fungi are promising sources of new nematicide products.Peer Reviewe