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Xylella fastidiosa (Xf) es una bacteria patógena que habita en el xilema de la planta hospedadora y el tracto digestivo de insectos que actúan como vectores. Afecta a un elevado número de especies vegetales, siendo una de las principales bacterias de cuarentena en la Unión Europea. Puesto que actualmente no existen medidas terapéuticas eficaces y los antibióticos están prohibidos en Europa, el control de Xf se basa principalmente en la erradicación de las plantas infectadas y el uso de compuestos químicos contra los vectores, pero estas medidas no son suficientes.

El conocimiento de la biología y dinámica poblacional de los insectos vectores de la bacteria fitopatógena Xylella fastidiosa Wells et al., 1987, es fundamental para llevar a cabo un adecuado control de las enfermedades que produce en plantas cultivadas, por medio del manejo de dichos vectores. En la Comunidad Valenciana, en la Zona Demarcada por presencia de la bacteria localizada en la provincia de Alicante, Philaenus spumarius (Linnaeus, 1758), Neophilaenus campestris (Fallén, 1805) y Neophilaenus lineatus (Linnaeus, 1758) han evidenciado portar la bacteria, si bien solo las dos primeras especies son vectores reconocidos en Europa.

Spittlebugs are responsible for the spread of Xylella fastidiosa in several European countries. This bacterium (X. fastidiosa subspecies multiplex) was found attacking almond trees in the Valencian Community (Eastern Spain) in 2017, producing the “Almond Leaf Scorch Disease”. Since then, Philaenus spumarius has been identified as the main insect species involved in transmission between plants. One key factor in understanding the epidemiology of the bacterium is to determine the host plant feeding preference of its insect vectors. One way to stablish this preference is studying the attraction of the vectors to the different plants, depending on the emitted volatile compounds. In this work, we are analyzing the attraction of P. spumarius to several host plants by using a Y-tube olfactometer. Individuals of P. spumarius came from a greeenhouse, where we reared the insects in semi-field conditions, or directly from the field. Common sowthistle (Sonchus oleraceus L.) has been used as a preferred host plant of the insect. Therefore bermuda grass (Cynodon dactylon (L.) Pers.), olive (Olea europea L., var Arbequina) and citrus (Citrus sinensis (L.) Osbeck, var Pineapple) have been compared against it. Besides activated common sowthistle (a plant previously attacked by insects) has been tested. The results have shown that: i) common sowthistle was preferred over no plant, ii) an activated common sowthistle was preferred over a not-activated plant, iii) common sowthistle was preferred over bermuda grass, iv) common sowthistle was preferred over citrus, and v) common sowthistle was similarly prefered to olive. In some cases, it seems that responses to plants depends on insect sex. The study is ongoing and more tests with P. spumarius, as well as the analysis of Neophilaenus campestris, are being carried out., ES; PPT; martinez_criaur@gva.es

In the outbreak of Xylella fastidiosa in the province of Alicante (mainland Spain), all isolates characterized so far belong to subsp. multiplex and ST6, and the main host is Prunus dulcis. Two different strains (IVIA 5901 and ESVL), isolated from almond trees in two municipalities of the Demarcated Area, were used to carry out pathogenicity tests on different plant species. The Italian strain De Donno (subsp. pauca, ST53) and the Spanish strain IVIA 5770 (subsp. fastidiosa, ST1) were also included. Five cultivars of Prunus dulcis, eight of Olea europaea, four of Vitis vinifera, Citrus limon, Citrus sinensis, Citrus reticulata, Diospyros kaki, Eriobotrya japonica, and the forest species Quercus suber and Q. ilex were challenged. A total of 35 plants for each species or cultivar were inoculated. At 1, 3, 6, 12 and 18 months post-inoculation (mpi) plants were sampled and analyzed by real-time PCR, to assess bacterial movement over time. The results show that, in general, no clear pattern of movement was found in the different plant species. Interestingly, in olive and grape, regardless the cultivar, the subsp. multiplex ST6 Alicante isolates were hardly detected from 12 mpi onwards, i.e. the systemic movement was very slow. In fact, they were only detected in less than 4% of the infected plants and with very late Cq values. In citrus plants, detection of these isolates failed since 3 mpi, as occurred in kaki and loquat trees. As for Quercus species, the detection rate was higher in Q. suber than in Q. ilex. Only in almond and cork oak trees, leaf scorch symptoms could be correlated with the presence of X. fastidiosa subsp. multiplex. Moreover, in these cases the pathogen was re-isolated. The timing and the level of detection for all the strains throughout the trial obtained so far are presented.

Xylella fastidiosa es una de las principales bacterias de cuarentena en la Unión Europea, que habita en el xilema de la planta hospedadora y el tracto digestivo de insectos que actúan como vectores. Se multiplica en los vasos conductores de numerosas especies vegetales, pudiendo llegar a obstruir el flujo de savia, lo que provoca síntomas de estrés hídrico que pueden causar la muerte de la planta. En España, las zonas con focos activos son las Islas Baleares y la Comunidad Valenciana, con diferencias en cuanto a las características genéticas de los aislados bacterianos y las especies vegetales afectadas.

Bacteriophage viruses are a promising tool for preventing and treating bacterial infections. In this sense, phage therapy is an eco-sustainable approach that has the potential to be used as either an alternative or a complement to other strategies for the management of Xylella fastidiosa diseases. The main objective of this work was the search, isolation, selection and characterization of bacteriophages against this phytopathogenic bacterium.

Xylella fastidiosa es una bacteria Gram-negativa de la familia Xanthomonadaceae que habita el xilema de la planta hospedadora, donde se multiplica y puede llegar a obstruir el flujo de savia bruta, pudiendo llegar a provocar la muerte de la planta. Tiene un modo de vida dual, ya que también habita en el tracto digestivo anterior de insectos chupadores de xilema que actúan como vectores. Afecta a un elevado número de especies vegetales, muchas de ellas de gran interés agrícola y medioambiental

Trabajo presentado en la 3rd European Conference on Xylella fastidiosa (Building knowledge, protecting plant health), celebrada online el 29 y 30 de abril de 2021., In the outbreak of Xylella fastidiosa in the province of Alicante (mainland Spain), all isolates characterized so far belong to subsp. multiplex and ST6, and the main host is Prunus dulcis. Two different strains (IVIA 5901 and ESVL), isolated from almond trees in two municipalities of the Demarcated Area, were used to carry out pathogenicity tests on different plant species. The Italian strain De Donno (subsp. pauca, ST53) and the Spanish strain IVIA 5770 (subsp. fastidiosa, ST1) were also included. Five cultivars of Prunus dulcis, eight of Olea europaea, four of Vitis vinifera, Citrus limon, Citrus sinensis, Citrus reticulata, Diospyros kaki, Eriobotrya japonica, and the forest species Quercus suber and Q. ilex were challenged. A total of 35 plants for each species or cultivar were inoculated. At 1, 3, 6, 12 and 18 months post-inoculation (mpi) plants were sampled and analyzed by real-time PCR, to assess bacterial movement over time. The results show that, in general, no clear pattern of movement was found in the different plant species. Interestingly, in olive and grape, regardless the cultivar, the subsp. multiplex ST6 Alicante isolates were hardly detected from 12 mpi onwards, i.e. the systemic movement was very slow. In fact, they were only detected in less than 4% of the infected plants and with very late Cq values. In citrus plants, detection of these isolates failed since 3 mpi, as occurred in kaki and loquat trees. As for Quercus species, the detection rate was higher in Q. suber than in Q. ilex. Only in almond and cork oak trees, leaf scorch symptoms could be correlated with the presence of X. fastidiosa subsp. multiplex. Moreover, in these cases the pathogen was re-isolated. The timing and the level of detection for all the strains throughout the trial obtained so far are presented.

Ante la apremiante situación originada para la agricultura en Europa por las enfermedades causadas por la bacteria Xylella fastidiosa, el estudio de su complejo patosistema se ha convertido en una necesidad ineludible. Un papel fundamental en este patosistema es el que representa el insecto vector, que es transmisor de la bacteria y de ahí la necesidad de su estudio. Esta tarea es complicada, en parte por la dificultad en encontrar poblaciones elevadas de estos insectos en campo, y especialmente por la naturaleza univoltina (una generación anual) de los mismos. Nuestro trabajo se ha encaminado a facilitar la provisión de ejemplares de los vectores, necesarios para la realización de bioensayos, poniendo a punto una cría en condiciones de semi-campo de las dos principales especies transmisoras de X. fastidiosa en Europa, Philaenus spumarius y Neophilaenus campestris. Para ello se trabajó en un invernadero de malla, utilizando como plantas hospedantes: Medicago sativa (alfalfa) para P. spumarius y Cynodon dactylon (grama) para N. campestris. Al mismo tiempo, se desarrolló un ensayo en laboratorio para dilucidar cómo afectan las condiciones de temperatura a la viabilidad de la puesta de P. spumarius. Los resultados obtenidos son prometedores: se desarrolló una primera generación de P. spumarius en 2020 y en 2021 queremos confirmar el desarrollo de la segunda generación. No ha ocurrido igual para N. campestris, indicándose los problemas surgidos; pero se quiere establecer dicha población en 2021. Se discute la complejidad de mantener una población de P. spumarius en condiciones controladas de laboratorio.

In the outbreak of Xylella fastidiosa in the province of Alicante (mainland Spain), all isolates characterized so far belong to subsp. multiplex and ST6, and the main host is Prunus dulcis. Two different strains (IVIA 5901 and ESVL), isolated from almond trees in two municipalities of the Demarcated Area, were used to carry out pathogenicity tests on different plant species. The Italian strain De Donno (subsp. pauca, ST53) and the Spanish strain IVIA 5770 (subsp. fastidiosa, ST1) were also included. Five cultivars of Prunus dulcis, eight of Olea europaea, four of Vitis vinifera, Citrus limon, Citrus sinensis, Citrus reticulata, Diospyros kaki, Eriobotrya japonica, and the forest species Quercus suber and Q. ilex were challenged. A total of 35 plants for each species or cultivar were inoculated. At 1, 3, 6, 12 and 18 months post-inoculation (mpi) plants were sampled and analyzed by real-time PCR, to assess bacterial movement over time. The results show that, in general, no clear pattern of movement was found in the different plant species. Interestingly, in olive and grape, regardless the cultivar, the subsp. multiplex ST6 Alicante isolates were hardly detected from 12 mpi onwards, i.e. the systemic movement was very slow. In fact, they were only detected in less than 4% of the infected plants and with very late Cq values. In citrus plants, detection of these isolates failed since 3 mpi, as occurred in kaki and loquat trees. As for Quercus species, the detection rate was higher in Q. suber than in Q. ilex. Only in almond and cork oak trees, leaf scorch symptoms could be correlated with the presence of X. fastidiosa subsp. multiplex. Moreover, in these cases the pathogen was re-isolated. The timing and the level of detection for all the strains throughout the trial obtained so far are presented.&nbsp

In the outbreak of Xylella fastidiosa in the province of Alicante (mainland Spain), all isolates characterized so far belong to subsp. multiplex and ST6, and the main host is Prunus dulcis. Two different strains (IVIA 5901 and ESVL), isolated from almond trees in two municipalities of the Demarcated Area, were used to carry out pathogenicity tests on different plant species. The Italian strain De Donno (subsp. pauca, ST53) and the Spanish strain IVIA 5770 (subsp. fastidiosa, ST1) were also included. Five cultivars of Prunus dulcis, eight of Olea europaea, four of Vitis vinifera, Citrus limon, Citrus sinensis, Citrus reticulata, Diospyros kaki, Eriobotrya japonica, and the forest species Quercus suber and Q. ilex were challenged. A total of 35 plants for each species or cultivar were inoculated. At 1, 3, 6, 12 and 18 months post-inoculation (mpi) plants were sampled and analyzed by real-time PCR, to assess bacterial movement over time. The results show that, in general, no clear pattern of movement was found in the different plant species. Interestingly, in olive and grape, regardless the cultivar, the subsp. multiplex ST6 Alicante isolates were hardly detected from 12 mpi onwards, i.e. the systemic movement was very slow. In fact, they were only detected in less than 4% of the infected plants and with very late Cq values. In citrus plants, detection of these isolates failed since 3 mpi, as occurred in kaki and loquat trees. As for Quercus species, the detection rate was higher in Q. suber than in Q. ilex. Only in almond and cork oak trees, leaf scorch symptoms could be correlated with the presence of X. fastidiosa subsp. multiplex. Moreover, in these cases the pathogen was re-isolated. The timing and the level of detection for all the strains throughout the trial obtained so far are presented., ES; PPT; marco_est@gva.es