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Plant-associated microbiota as a source of antagonistic bacteria against the phytopathogen Erwinia amylovora
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Barbé, Silvia
- Figàs-Segura, Àngela
- Benada, M'hamed
- Navarro-Herrero, Inmaculada
- Sampaio, Telma Maria
- G. Biosca, Elena
- Marco-Noales, Ester
Control of bacterial plant diseases is a major concern, as they affect economically important species and spread easily, such as the case of fire blight of rosaceous caused by Erwinia amylovora. In the search for alternatives to the use of agrochemicals and antibiotics, this work presents a screening of natural bacterial antagonists of this relevant and devastating phytopathogen. We recovered bacterial isolates from different plant tissues and geographical origins and then selected those with the strongest ability to reduce fire blight symptoms ex vivo and remarkable in vitro antagonistic activity against E. amylovora. None of them elicited a hypersensitivity reaction in tobacco leaves, most produced several hydrolytic enzymes and presented other biocontrol and/or plant growth-promoting activities, such as siderophore production and phosphate solubilization. These isolates, considered as biocontrol candidates, were identified by 16S rRNA sequencing as Pseudomonas rhizosphaerae, Curtobacterium flaccumfaciens, Enterobacter cancerogenus, Pseudomonas azotoformans, Rosenbergiella epipactidis and Serratia plymuthica. This is the first time that the last five bacterial species are reported to have biocontrol potential against E. amylovora.
Discovery and Diagnosis of a New Sobemovirus Infecting Cyperus esculentus Showing Leaf Yellow Mosaic and Dwarfism Using Small-RNA High Throughput Sequencing
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Rubio, Luis
- Guinot-Moreno, Francisco J.
- Sanz-López, Carmen
- Galipienso, Luis
C. esculentus is a profitable crop in Valencia, Spain, but the emergence of a disease causing of leaf yellow mosaic, dwarfism, and a drastic decrease in tuber production has become a problem. The small-RNA high-throughput sequencing (HTS) of a diseased C. esculentus plant identified only one virus, which could be the causal agent of this disease. The amino-acid comparison with viral sequences from GenBank and phylogenetic analyses indicated that this was a new species of genus Sobemovirus, and the name Xufa yellow dwarf virus was proposed. Completion with Sanger sequencing yielded a contig of 3072 nt corresponding to about 75% of the typical genome of sobemoviruses, including ORFs 2a (polyprotein-containing protease, VPG, and other proteins), 2b (RNA-dependent RNA polymerase), and 3 (coat protein). The nucleotide sequence was used to develop fast and accurate methods for the detection and quantification of xufa yellow dwarf virus (XYDV) based on reverse transcription (RT) and DNA amplification. XYDV was detected in leaves and tubers and showed a high incidence in the field in both symptomatic (almost 100%) and asymptomatic (70%) plants, but its accumulation was much higher in symptomatic plants. The relevance of these results for disease control was discussed.
Un nuevo enfoque sostenible de gestión de plagas y enfermedades a través de la inducción de defensas de las plantas
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Pérez-Hedo, Mertixell
- Urbaneja, Alberto
Las plantas son capaces de activar defensas en respuesta al ataque de herbívoros. Estas defensas pueden ser directas o indirectas, y pueden aprovecharse para su integración en programas de gestión sostenible de plagas y enfermedades. En estudios realizados por el IVIA, se ha demostrado que la exposición de plantas de tomate, pimiento y cítricos a varios volátiles inducidos por herbivoría (HIPV’s) aumentan la sobreexpresión de genes defensivos en comparación con plantas no expuestas. De estos volátiles, se ha seleccionado el (Z)-3-hexenil propanoato [(Z)-3-HP] por su capacidad para activar diversas rutas defensivas en los tres cultivos. Además, se ha confirmado que la exposición a (Z)-3-HP aumenta la producción de compuestos derivados de ácidos grasos y la acumulación de compuestos de defensa específicos. Para su aplicación práctica, y en colaboración con el grupo del CEQA de la UPV, se diseñaron difusores poliméricos de liberación controlada que son capaces de emitir (Z)-3-HP a tasas constantes durante períodos prolongados y que ya han sido probados en condiciones de campo en los tres cultivos mencionados. Los resultados obtenidos sugieren que el uso de HIPV’s puede ser una estrategia prometedora para la gestión sostenible de plagas y enfermedades en agricultura.
Laser Microdissection: A High-Precision Approach to Isolate Specific Cell Types from Any Plant Species for Downstream Molecular Analyses
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Tadeo, Francisco R.
- Agustí, Manuel
- Merelo, Paz
- Talón, Manuel
Plants display a great diversity of particular cell types that obviously perform functions and regulations that are essential for successful growth and development, whether under optimal or adverse conditions. The functions performed by each of these particular cell types must be associated with specific transcriptomic, proteomic, and metabolic profiles that cannot be disentangled by analyzing whole plant organs and tissues. Laser microdissection is a technique for the collection of specific cell types in plant organs and tissues comprising heterogeneous cell populations. It has been successfully used for physiological and molecular studies. Laser microdissection can be applied to any plant species as long as it is possible to reliably identify the cell types of interest. Here, we describe step by step, using citrus as a model plant, a fast, simple, easy to perform, and experimentally validated protocol to collect cells from the abscission zone, a specific tissue that is difficult to access and whose activity is important in the response of plants to adverse environmental conditions.
La expansión de psílidos transmisores de HLB en la cuenca del Mediterráneo
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Urbaneja, Alberto
- Pérez-Hedo, Mertixell
- Tena, Alejandro
El HLB es la enfermedad más grave y destructiva de la citricultura mundial. Esta enfermedad está causada por la bacteria Candidatus Liberibacter, que se transmite principalmente por dos insectos vectores: el psílido asiático de los cítricos, Diaphorina citri Kuwayama (Hemiptera: Liviidae) y el psílido africano, Trioza erytreae Del Guercio (Hemiptera: Triozidae). Actualmente, la citricultura mediterránea española está libre de ambos vectores, así como del HLB. Sin embargo, la amenaza de su presencia está cada vez más cerca. Por una parte, T. erytreae se detectó en Galicia en 2014 y se ha ido propagando por la cornisa cantábrica y la costa atlántica portuguesa, llegando ya al Algarve portugués, a solo 120 km de la zona citrícola española de Huelva. Por otra, en julio de 2021, Diaphorina citri se detectó por primera vez en la cuenca mediterránea, concretamente en la región de Emek Hefer, en Israel. A pesar de los esfuerzos en su erradicación, D. citri se ha propagado a otras zonas al norte de Israel, principalmente parques y jardines privados, alcanzando ya el valle del Jordán. El potencial biótico de D. citri es mucho mayor que T. erytreae y es capaz de multiplicarse rápidamente sobre las principales variedades y especies de cítricos cultivadas en el Mediterráneo. Por tanto, se debe permanecer alerta y estar preparados para dar una respuesta rápida y coordinada en caso de detección de esta amenaza.
The Dual Benefit of Plant Essential Oils against Tuta absoluta
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Ben Abdallah, Saoussen
- Riahi, Chaymaa
- Vacas, Sandra
- Navarro-Llopis, Vicente
- Urbaneja, Alberto
- Pérez-Hedo, Mertixell
Plant essential oils (PEOs) are being studied as a potential alternative to synthetic pesticides in agriculture. PEOs have the potential to control pests both directly, by being toxic or repellent to pests, and indirectly, by activating plant’s defense mechanisms. In this study, the effectiveness of five PEOs (Achillea millefolium, Allium sativum, Rosmarinus officinallis, Tagetes minuta, and Thymus zygis) on controlling Tuta absoluta and their impact on the predator Nesidiocoris tenuis was examined. The study revelead that PEOs from A. millefolium and A. sativum-sprayed plants significantly reduced the number of T. absoluta-infested leaflets and did not affect the establishment and reproduction of N. tenuis. Additionally, the spraying of A. millefolium and A. sativum increased the expression of defense genes in the plants, triggering the release of herbivory-induced plant volatiles (HIPVs), such as C6 green leaf volatiles, monoterpenes, and aldehydes, which can be messengers in tritrophic interactions. The results suggest that PEOs from A. millefolium and A. sativum can provide a dual benefit for controlling arthropod pests, as they can directly exhibit toxicity against these pests while also activating plant defense mechanisms. Overall, this study provides new insights into using PEOs as a sustainable solution for controlling pests and diseases in agriculture, by reducing synthetic pesticides and promoting the use of natural predators.
Comparative Analysis of Novel Lytic Phages for Biological Control of Phytopathogenic Xanthomonas spp.
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Domingo-Calap, María L.
- Bernabeu-Gimeno, Mireia
- Aure, Cristina M.
- Marco-Noales, Ester
- Domingo-Calap, Pilar
Xanthomonas is an important genus of plant-pathogenic bacteria that affects agronomic and economically important crops, causing serious economic losses. In fact, several Xanthomonas species are considered regulated quarantine pests. Due to the lack of effective control measures to treat plant-pathogenic bacteria, innovative control tools are needed to carry out integrated disease management. In this regard, bacteriophages (phages), viruses of bacteria, constitute a promising biocontrol tool. In this work, we report the isolation and characterization of 11 novel Xanthomonas arboricola pv. juglandis phages belonging to different families and genera of the class Caudoviricetes. Infectivity matrix in more than 60 isolates of different xanthomonads and other phytopathogenic bacteria suggests that these phages are specific to the Xanthomonas genus, with different host ranges depending on the isolates tested. Interestingly, some of these phages showed relevant features to be used as biocontrol tools to combat pathogenic Xanthomonas spp. as important as X. oryzae or X. citri. *Importance: Phytopathogenic bacteria represent serious losses worldwide. The lack of current treatments has focused the spotlight on phages, viruses of bacteria, as very promising biocontrol tools. Phages are very specific and can help to control bacterial infections in crops, as is the case of xanthomonads-associated diseases. The discovery of new environmental phages with lytic capacity that can help to combat these pathogens is of special relevance, and it is necessary to implement phage isolation and characterization techniques to determine their host range and their genomic properties. The establishment of phage collections worldwide will allow their use as preventive, diagnostic, or therapeutic tools. Although there is still a long way to go, this work is a step forward in the implementation of new ecofriendly techniques to combat key pathogens in the field.
DOI: https://hdl.handle.net/20.500.11939/8619, https://journals.asm.org/doi/10.1128/spectrum.02960-22
Real-time on-site detection of the three ‘Candidatus Liberibacter’ species associated with HLB disease: a rapid and validated method
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Morán, Félix
- Herrero-Cervera, Mario
- Carvajal-Rojas, Sofía
- Marco-Noales, Ester
Huanglongbing (HLB) is a devastating disease that affects all commercial citrus species worldwide. The disease is associated with bacteria of three species of the genus ‘Candidatus Liberibacter’ transmitted by psyllid vectors. To date, HLB has no cure, so preventing its introduction into HLB-free areas is the best strategy to control its spread. For that, the use of accurate, sensitive, specific, and reliable detection methods is critical for good integrated management of this serious disease. This study presents a new real-time recombinase polymerase amplification (RPA) protocol able to detect the three ‘Ca. Liberibacter’ species associated with HLB in both plant and insect samples, validated according to European and Mediterranean Plant Protection Organization (EPPO) guidelines and tested on 365 samples from nine different geographic origins. This new protocol does not require nucleic acid purification or specialized equipment, making it ideal to be used under field conditions. It is based on specific primers and probe targeting a region of fusA gene, which shows a specificity of 94%– 100%, both in silico and in vitro, for the ‘Ca. Liberibacter’ species associated with HLB. The analytical sensitivity of the new protocol is excellent, with a reliable detection limit in the order of 101 copies per microliter in HLB-infected plant and insect material. The repeatability and reproducibility of the new methods showed consistent results. Diagnostic parameters of the new RPA protocol were calculated and compared with the gold standard technique, a quantitative real-time PCR, in both crude extracts of citrus plants and insect vectors. The agreement between the two techniques was almost perfect according to the estimated Cohen’s kappa index, with a diagnostic sensitivity and specificity of 83.89% and 100%, respectively, and a relative accuracy of 91.59%. Moreover, the results are obtained in less than 35 min. All these results indicate the potential of this new RPA protocol to be implemented as a reliable on-site detection kit for HLB due to its simplicity, speed, and portability.
Temperature-Driven Selection of Predatory Mirid Bugs for Improving Aphid Control in Sweet Pepper Crops
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Pérez-Hedo, Mertixell
- Pedroche, Virginia
- Urbaneja, Alberto
Recent studies have suggested that predatory mirid bugs may be an effective alternative for controlling aphids in sweet pepper greenhouses. This study examined the effect of three constant temperatures (18, 24, and 30 °C) on the life history traits of predatory mirid species Nesidiocoris tenuis, Macrolophus pygmaeus, and Dicyphus bolivari, preying on the aphid Myzus persicae nicotianae in sweet pepper plants. As the temperature increased, the survival rate decreased for M. pygmaeus and D. bolivari, while for N. tenuis, it was the opposite, and their survival increased. When considering all the biological traits studied together, the estimated intrinsic rate of increase (rm) decreased as the temperature increased for M. pygmaeus and D. bolivari. In contrast, the rate increased as the temperature increased for N. tenuis. These results suggest that M. pygmaeus and D. bolivari are better adapted to lower temperatures than N. tenuis, which is more adapted to warm temperatures. The implications of these results for improving the biological control of aphids in sweet pepper greenhouses through the use of mirid bugs are discussed in relation to different temperature regimes.
Anagyrus fusceventris como principal agente de control biológico de Pseudococcus longispinus en caqui
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Plata, Ángel
- da-Cruz, Mariana
- Gómez-Martínez, María A.
- Beitia, Francisco
- Tena, Alejandro
Pseudococcus longispinus representa la principal plaga en el cultivo de caqui en España. Debido a la problemática que conlleva el uso de insecticidas y la baja eficacia que tienen contra esta plaga, es necesario implementar estrategias basadas en el control biológico para reducir su abundancia. Los
parasitoides se consideran agentes de control biológico clave para el control de pseudocóccidos. En
este trabajo se ha estudiado el complejo de parasitoides que ataca a P. longispinus en caquis de la
Comunidad Valenciana. El parasitismo alcanzó su máximo en otoño, cuando la plaga es más abundante.
La mayoría de pseudocóccidos parasitados se encontraban en estados de desarrollo avanzado: ninfas de tercer estadío y hembras adultas. El parasitoide más abundante y ampliamente distribuido fue Anagyrus fusciventris. Sin embargo, el parasitismo fue muy variable entre parcelas y años. Esta eficacia variable puede deberse a varios factores como son los hiperparasitoides, las hormigas y los insecticidas. Actualmente, el IVIA está trabajando para mejorar la eficacia de este parasitoide.
parasitoides se consideran agentes de control biológico clave para el control de pseudocóccidos. En
este trabajo se ha estudiado el complejo de parasitoides que ataca a P. longispinus en caquis de la
Comunidad Valenciana. El parasitismo alcanzó su máximo en otoño, cuando la plaga es más abundante.
La mayoría de pseudocóccidos parasitados se encontraban en estados de desarrollo avanzado: ninfas de tercer estadío y hembras adultas. El parasitoide más abundante y ampliamente distribuido fue Anagyrus fusciventris. Sin embargo, el parasitismo fue muy variable entre parcelas y años. Esta eficacia variable puede deberse a varios factores como son los hiperparasitoides, las hormigas y los insecticidas. Actualmente, el IVIA está trabajando para mejorar la eficacia de este parasitoide.
Incidencia de la espuma producida por ninfas de Philaenus spumarius (Hemiptera: Aphrophoridae), el principal insecto vector de Xylella fastidiosa en Europa, frente a la acción de enemigos naturales
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- García-García, Rosalía
- Bernat-Ponce, Saúl
- Beitia, Francisco J.
- Nieves-Carretero, Lorena
- Aure, Cristina M.
La bacteria Xylella fastidiosa se transmite entre plantas por medio de insectos vectores; el buen conocimiento del desarrollo de las poblaciones de estos puede facilitar una regulación adecuada de la expansión de la bacteria. Y un aspecto fundamental a considerar actualmente es la posibilidad de ejercer un sistema de control biológico de estos insectos, para lo cual se evidencia como necesario determinar qué agentes de control biológico pueden detectarse en el campo y cómo pueden incidir sobre los vectores de la bacteria. En la actualidad se conocen algunos enemigos naturales del principal vector de X. fastidiosa, el insecto afrofórido Philaenus spumarius; tanto depredadores como parasitoides de sus fases de desarrollo de huevo y adulto. Pero poco se sabe de algún enemigo natural que actúe sobre las ninfas del insecto, que están protegidas por la espuma que ellas mismas producen. Por ello, parece interesante determinar el efecto protector real de dicha espuma, que pueda interferir en la acción de esos enemigos naturales, lo cual es el objetivo principal del trabajo que aquí se presenta.
Proyecto: ERDF/PCV 2021-2027/52202
Garlic and peppermint essential oils elicit plant defensive responses in sweet peppers
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Ricupero, Michele
- Biondi, Antonio
- Campolo, Orlando
- Alonso-Valiente, Miquel
- Gallego, Carolina
- Zappala, Lucia
- Urbaneja, Alberto
- Pérez-Hedo, Mertixell
Exploiting plant defense mechanisms is a promising tool for pest management in modern agriculture. Plant Essential Oils (EOs) are used for the sustainable control of agricultural pests; however, their impact on plant defense has been scarcely investigated. In this work, we study for the first time whether the spraying of EOs can activate plant defense mechanisms in sweet pepper. The olfactory capacity of Encarsia formosa (Hymenoptera: Aphelinidae) to respond to defense-activated plants was used to select garlic and peppermint EOs among nine EOs sprayed on sweet peppers. The expression level of defense-related genes in plant tissues and the phytotoxicity were measured in response to EO foliar applications. Moreover, the olfactory responses of the herbivores, Bemisia tabaci (Hemiptera: Aleyrodidae) and Frankliniella occidentalis (Thysanoptera: Thripidae), and their natural enemies, Orius laevigatus (Hemiptera: Anthocoridae) and Nesidiocoris tenuis (Hemiptera: Miridae), to EO induced plant volatiles were also investigated. The gene expression analysis revealed activated jasmonic and salicylic acid defense signaling pathways in EO sprayed sweet pepper plants and a negligible phytotoxic effect was recorded. Choice tests revealed varying behavioral responses in selected insect models when plants were treated with garlic and peppermint EOs in different concentrations. Our results suggest that garlic and peppermint EO spray applications can enhance the defense mechanisms of sweet peppers and have a cascading bottom-up effects on the associated food chain. These initial findings provide a foundation for the future development of Integrated Pest Management strategies to protect solanaceous crops.
Proyecto: ERDF/PCV 2021-2027/52202
RNAi-mediated silencing of Mediterranean fruit fly (Ceratitis capitata) endogenous genes using orally-supplied double-stranded RNAs produced in Escherichia coli
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Ortolá, Beltrán
- Urbaneja, Alberto
- Eiras, Marcelo
- Pérez-Hedo, Mertixell
- Daros, José A.
BACKGROUND: The Mediterranean fruit fly (medfly), Ceratitis capitata Wiedemann, is a major pest affecting fruit and vegetable production worldwide, whose control is mainly based on insecticides. Double-stranded RNA (dsRNA) able to down-regulate endogenous genes, thus affecting essential vital functions via RNA interference (RNAi) in pests and pathogens, is envisioned as a more specific and environmentally-friendly alternative to traditional insecticides. However, this strategy has not been explored in medfly yet. RESULTS: Here, we screened seven candidate target genes by injecting in adult medflies gene-specific dsRNA hairpins transcribed in vitro. Several genes were significantly down-regulated, resulting in increased insect mortality compared to flies treated with a control dsRNA targeting the green fluorescent protein (GFP) complementary DNA (cDNA). Three of the dsRNAs, homologous to the beta subunit of adenosine triphosphate (ATP) synthase (ATPsynbeta), a vacuolar ATPase (V-ATPase), and the ribosomal protein S13 (RPS13), were able to halve the probability of survival in only 48 h after injection. We then produced new versions of these three dsRNAs and that of the GFP control as circular molecules in Escherichia coli using a two-self-splicing-intron-based expression system and tested them as orally-delivered insecticidal compounds against medfly adults. We observed a significant down-regulation of V-ATPase and RPS13 messenger RNAs (mRNAs) (approximately 30% and 90%, respectively) compared with the control medflies after 3 days of treatment. No significant mortality was recorded in medflies, but egg laying and hatching reduction was achieved by silencing V-ATPase and RPS13. CONCLUSION: In sum, we report the potential of dsRNA molecules as oral insecticide in medfly.
DOI: https://hdl.handle.net/20.500.11939/8735, https://onlinelibrary.wiley.com/doi/full/10.1002/ps.7839
Covert infection with an RNA virus affects medfly fitness and the interaction with its natural parasitoid Aganaspis daci
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Hernández-Pelegrín, Luis
- García-Martínez, Ricardo
- Llácer, Elena
- Nieves-Carretero, Lorena
- Llopis-Giménez, Ángel
- Català-Oltra, Marta
- Dembilio, Óscar
- Pérez-Hedo, Mertixell
- Urbaneja, Alberto
- Ros, Vera
- Beitia, Francisco J.
- Herrero, Salvador
With the advent of high-throughput sequencing, large sets of insect-infecting RNA viruses producing apparent asymptomatic infections are being discovered. In the Mediterranean fruit fly (medfly) Ceratitis capitata, an agricultural key pest of a wide range of fruits, 13 different RNA viruses have been described so far. Recent analysis demonstrated a wide distribution of these viruses in different medfly strains collected worldwide, but little is known about the interactions between those viruses and the medfly host. Previous studies suggested that a higher abundance of Ceratitis capitata nora virus (CcaNV) correlated with a shorter lifespan in adults. Here, we investigated the effect of CcaNV on a broad range of parameters related to host fitness and its interaction with other trophic levels. CcaNV purified from a naturally infected medfly strain was added to the larval diet. Pupal weight, adult emergence, flying ability, and longevity were monitored after oral infections. Our results revealed detrimental effects associated with a CcaNV infection in the medfly, in terms of reduced pupal weight and reduced adult longevity. Moreover, we tested the influence of a CcaNV infection in medflies on the parasitism performance of Aganaspis daci, an endoparasitoid used in biological control programs against medflies. Our results showed that A. daci progeny increased when parasitizing on CcaNV-infected larvae. Overall, we proved that covert RNA viruses can impact the insect ecology, directly affecting its insect host biology and indirectly influencing multitrophic interactions.
Optimizando la gestión eficiente de plagas a través de investigación práctica y aplicada: cómo el asesor agrícola puede mejorar la toma de decisiones
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Urbaneja, Alberto
La gestión de plagas agrícolas plantea desafíos significativos que tienen un impacto directo en la productividad de los cultivos. Para abordar estos desafíos, la investigación aplicada desempeña un papel crucial. Esta investigación debe proporcionar a los asesores agrícolas y agricultores las herramientas y técnicas necesarias, como la monitorización adecuada o estrategias de control de plagas. Los asesores agrícolas desempeñan un papel fundamental al guiar a los agricultores en la implementación
de estrategias efectivas para la gestión de plagas. En el complejo escenario actual, marcado por el cambio climático y la creciente detección de plagas exóticas, la innovación y la adaptación de estrategias de control se vuelven indispensables. Por lo tanto, la transferencia de conocimientos y la capacitación son fundamentales para mantenerse al día con las últimas investigaciones y las prácticas recomendadas.
de estrategias efectivas para la gestión de plagas. En el complejo escenario actual, marcado por el cambio climático y la creciente detección de plagas exóticas, la innovación y la adaptación de estrategias de control se vuelven indispensables. Por lo tanto, la transferencia de conocimientos y la capacitación son fundamentales para mantenerse al día con las últimas investigaciones y las prácticas recomendadas.
Proyecto: ERDF/PCV 2021-2027/52202
Enhancing the biocontrol potential of the predator Nesidiocoris tenuis through genetic selection
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Pérez-Hedo, Mertixell
- Ortells-Fabra, Raúl
- Alonso-Valiente, Miquel
- Ruiz-Rivero, Omar
- Urbaneja, Alberto
The zoophytophagous Nesidiocoris tenuis has proven to be a highly effective natural enemy against tomato key pests. It can enhance tomato plants' defenses due to its phytophagous behavior. However, its plant feeding can result in severe plant damage when prey is scarce. Previous studies using an isofemale line demonstrated the dietary habits of N. tenuis are genetically regulated, specifically with regard to phytophagy and zoophagy. In this study, we assessed the life-history traits of the IVIA strain, selected for over 50 generations for its zoophagy and phytophagy, compared to a commercial strain. The IVIA strain developed 3.5% faster, had 34% more offspring, preyed on 34% more Ephestia kuehniella eggs, and caused 50% fewer necrotic rings on tomato plants than the commercial strain. The IVIA strain controlled B. tabaci and T. absoluta in greenhouse experiments at the same level as the commercial strain but produced less damage to the plant. We also studied the capacity of the IVIA strain to induce plant defenses. The IVIA strain increased plant defenses compared to the control, although to a lesser extent than the commercial strain. This finding confirms the reduced phytophagy of the IVIA strain. Interestingly, the use of microsatellite markers revealed genetic differentiation between the IVIA strain and the commercial strain. Our results highlight the potential of selective breeding for improving biocontrol traits of interest in N. tenuis and open the door to differentiating selected races of N. tenuis using molecular techniques.
Proyecto: ERDF/PCV 2021-2027/52202
An insect’s energy bar: the potential role of plant guttation on biological control
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Urbaneja-Bernat, Pablo
- Tena, Alejandro
- González-Cabrera, Joel
- Rodríguez-Saona, César
Plant guttation is an exudation fluid composed of xylem and phloem sap secreted at the margins of leaves of many agricultural crops. Although plant guttation is a widespread phenomenon, its effect on natural enemies remains largely unexplored. A recent study showed that plant guttation can be a reliable nutrient-rich food source for natural enemies, affecting their communities in highbush blueberries. This review highlights the potential role of plant guttation as a food source for natural enemies, with a particular emphasis on its nutritional value, effects on insect communities, and potential use in conservation biological control. We also discuss possible negative implications and conclude with some open questions and future directions for research.
Proyecto: ERDF/PCV 2021-2027/52202
Mealybugs in Mediterranean persimmon: fruit infestation, seasonal trend and effect of climate change
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Plata, Ángel
- Gómez-Martínez, María A.
- Beitia, Francisco J.
- Tena, Alejandro
Mealybugs (Hemiptera: Pseudococcidae) are the main pest of persimmon in Spain, the second producer in the world. In order to develop an Integrated Pest Management (IPM) program, it is necessary to identify the main mealybug species, determine their phenology, and develop tools to predict damage. To do this, we sampled 17 orchards from the main persimmon producing area in Spain over two years. Pseudococcus longispinus (Targioni-Tozzeti) was the most abundant and widely distributed species. This mealybug species completed three generations per year and reached peak density just before harvest. Fruit infestation at harvest was highly correlated with mealybug density in spring and summer. The estimated thermal constants to complete development and one generation were 512.5 and 956.3 degree days, respectively. Based on climate change predictions, crop damage caused by the third generation of P. longispinus will increase in 2040 and the mealybug will complete a fourth generation by 2080. Pseudococcus longispinus has become the main pest for Mediterranean persimmon and damage produced by this mealybug may be exacerbated by climate change. This work provides essential data to design a sampling protocol and determine intervention times and thresholds against this mealybug.
Proyecto: ERDF/PCV 2021-2027/52202
Honeydew management to promote biological control
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Fernández-de-Bobadilla, Maite
- Ramírez, Natalia M.
- Calvo-Agudo, Miguel
- Dicke, Marcel
- Tena, Alejandro
Honeydew is the excretion of plant-feeding hemipterans and it is one of the most abundant source of carbohydrates for parasitoids and predators in agroecosystems. Being so abundant, honeydew mediates direct and indirect interactions that affect biological control. We describe these interactions and identify honeydew-management strategies to reduce pest pressure. First, the presence of nondamaging honeydew producers in cover crops and hedges increases the efficacy of parasitoids and predators. Second, breaking the mutualism between ants and honeydew-producing pests with alternative sugar sources promotes biological control of these pests. Third, we propose to explore honeydew volatiles to attract biological control agents and repel pests, as well as to induce plant defenses. Finally, we urge reducing the use of systemic pesticides that contaminate honeydew and negatively affect biological control agents that feed on it. Overall, we propose that honeydew management is integrated in pest management programs to contribute to sustainable agriculture.
Proyecto: ERDF/PCV 2021-2027/52202
Rapid detection of tomato spotted wilt virus by real-time RT-LAMP and in-field application
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Caruso, A. G.
- Ragona, A.
- Agrò, G.
- Bertacca, S.
- Yahyaoui, E.
- Galipienso, Luis
- Rubio, Luis
- Panno, Stefano
- Davino, Salvatore
Tomato spotted wilt virus (TSWV) is considered one of the most threatening viruses worldwide for diferent economically important agricultural crops. In this scenario, it is important to perform an early detection by laboratory tests to prevent TSWV spread. A rapid and sensitive TSWV detection protocol based on real time reverse transcription loop-mediated isothermal amplifcation (RT-LAMP) assay was developed in this work, also using cost-efective and simplifed sample preparation procedure, to assess the suitability of the RT-LAMP assay in feld conditions on tomato and pepper samples. A set of six primers was designed within the nucleotide sequence region coding for the nucleocapsid protein (N) of segment S, targeting a 220-nucleotide sequence. Sensitivity, specifcity, accuracy, and in-feld application of the real-time RT-LAMP assay were evaluated. The developed real-time RT-LAMP assay proved to be one thousand and one hundred times more sensitive than end-point RT-PCR and real-time RT-PCR methods, respectively, detecting a total of 9.191 × 101 genome copies as minimum target, and no cross-reactivity were detected with other viruses belonging to Tospoviridae and Bromoviridae families used as outgroup. In addition, the in-feld application of the assay using the rapid sample preparation gave adequate and reliable results within 60 minutes, with an acceptable reaction delay when compared to canonical RNA extraction. The in-feld analyses showed an increase of TSWV-positive samples (37%) detection compared
with end-point RT-PCR and real-time RT-PCR (32% and 29%, respectively), particularly on asymptomatic samples, confrming that the real-time RT-LAMP assay can be implemented as a routine test both in-feld and laboratory conditions as a rapid and sensitive technique for TSWV detection.
with end-point RT-PCR and real-time RT-PCR (32% and 29%, respectively), particularly on asymptomatic samples, confrming that the real-time RT-LAMP assay can be implemented as a routine test both in-feld and laboratory conditions as a rapid and sensitive technique for TSWV detection.
Proyecto: ERDF/PCV 2021-2027/52202
Two Better Than One? Potential Effects of Intraguild Predation on the Biological Control of Ceratitis capitata (Diptera: Tephritidae) by the Parasitoid Aganaspis daci (Hymenoptera: Figitidae) and the Predator Pseudoophonus rufipes (Coleoptera: Carabidae)
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- De-Pedro, Luis
- Beitia, Francisco J.
- Tormos, José
The use of more than one species to manage a single insect pest is a common practice
among biological control programs. However, the beneficial effects of natural enemies are not always
additive, which in many cases may be attributed to interspecific interactions such as intraguild
predation (IGP). Herein, we investigated the potential IGP between two relevant natural enemies of
the Medfly (Ceratitis capitata), the predator Pseudoophonus rufipes and the parasitoid Aganaspis daci,
as well as the possible implications of this phenomenon in their efficiency as biocontrol agents. To
this end, we assessed their functional responses and different demographic parameters when acting
alone and together against C. capitata under laboratory conditions. Coexistence led to a switch in the
functional response of both species, from type III to type II in A. daci and the opposite in P. rufipes.
Regarding demographic parameters, coexistence resulted in higher parasitoidism and population
reduction by A. daci only at low host densities, probably due to competition pressure. In the same
circumstances, P. rufipes reduced its predatory activity, rejecting those larvae that were presumably
parasitized and causing negligible IGP. At high Medfly densities, A. daci efficiency decreased, and
the reduced encounter probability enhanced the predatory activity by P. rufipes. As a result of these
trends, Medfly population reduction reached almost 100% at all densities, which suggests an additive
effect of both natural enemies and recommends combined releases of these agents as a strategy for
the control of the Medfly.
among biological control programs. However, the beneficial effects of natural enemies are not always
additive, which in many cases may be attributed to interspecific interactions such as intraguild
predation (IGP). Herein, we investigated the potential IGP between two relevant natural enemies of
the Medfly (Ceratitis capitata), the predator Pseudoophonus rufipes and the parasitoid Aganaspis daci,
as well as the possible implications of this phenomenon in their efficiency as biocontrol agents. To
this end, we assessed their functional responses and different demographic parameters when acting
alone and together against C. capitata under laboratory conditions. Coexistence led to a switch in the
functional response of both species, from type III to type II in A. daci and the opposite in P. rufipes.
Regarding demographic parameters, coexistence resulted in higher parasitoidism and population
reduction by A. daci only at low host densities, probably due to competition pressure. In the same
circumstances, P. rufipes reduced its predatory activity, rejecting those larvae that were presumably
parasitized and causing negligible IGP. At high Medfly densities, A. daci efficiency decreased, and
the reduced encounter probability enhanced the predatory activity by P. rufipes. As a result of these
trends, Medfly population reduction reached almost 100% at all densities, which suggests an additive
effect of both natural enemies and recommends combined releases of these agents as a strategy for
the control of the Medfly.
Proyecto: ERDF/PCV 2021-2027/52202
Homobrassinolide Delays Huanglongbing Progression in Newly Planted Citrus (Citrus sinensis) Trees
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Pérez-Hedo, Mertixell
- Urbaneja, Alberto
- Alférez, Fernando
Huanglongbing (HLB), or citrus greening, is a devastating disease impacting citrus trees
worldwide, with severe effects particularly noted in Florida. Current strategies to combat HLB focus
on aggressive replanting, despite the high susceptibility of young trees to infection. In this context,
it is critical to explore agronomic practices that can enhance the health and resistance of young
citrus trees to HLB. Here, we demonstrate that treatment with homobrassinolide (HBr), a type of
brassinosteroid, in newly planted citrus (Citrus sinensis) trees can delay HLB infection and improve
tree health amidst the high psyllid pressure conditions endemic to Florida. Our study reveals a
significant reduction in HLB infection rates in HBr-treated trees compared to control trees, with only
25% of treated trees testing positive for HLB by six months, in contrast to 100% infection in untreated
trees. This delay in infection may be attributed to HBr inducing an immune response and negatively
impacting psyllid performance, as subsequently demonstrated in a greenhouse experiment. Our
findings suggest that HBr applications could serve as a viable strategy to enhance the resilience of
citrus production against HLB, underscoring the need for further investigation into their mechanisms
of action and potential role in a comprehensive pest and disease management strategy.
worldwide, with severe effects particularly noted in Florida. Current strategies to combat HLB focus
on aggressive replanting, despite the high susceptibility of young trees to infection. In this context,
it is critical to explore agronomic practices that can enhance the health and resistance of young
citrus trees to HLB. Here, we demonstrate that treatment with homobrassinolide (HBr), a type of
brassinosteroid, in newly planted citrus (Citrus sinensis) trees can delay HLB infection and improve
tree health amidst the high psyllid pressure conditions endemic to Florida. Our study reveals a
significant reduction in HLB infection rates in HBr-treated trees compared to control trees, with only
25% of treated trees testing positive for HLB by six months, in contrast to 100% infection in untreated
trees. This delay in infection may be attributed to HBr inducing an immune response and negatively
impacting psyllid performance, as subsequently demonstrated in a greenhouse experiment. Our
findings suggest that HBr applications could serve as a viable strategy to enhance the resilience of
citrus production against HLB, underscoring the need for further investigation into their mechanisms
of action and potential role in a comprehensive pest and disease management strategy.
Advancing tomato crop protection: Green leaf volatile-mediated defense mechanisms against Nesidiocoris tenuis plant damage
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Depalo, Laura
- Gallego, Carolina
- Ortells-Fabra, Raúl
- Salas, Carlos
- Montalt, Rafael
- Urbaneja, Alberto
- Pérez-Hedo, Mertixell
Although Nesidiocoris tenuis is highly effective as a biological control agent, it can also damage tomato plants due
to its zoophytophagous behavior. When N. tenuis pierces the stems and petioles of tomato plants with its stylets, it
triggers callose deposition and subsequent cell death, resulting in blocked nutrient transport, floral abortions, or
wilting of tender shoots. Recently, it has been shown that exposure of tomato plants to the green leaf volatile (Z)-
3-hexenyl propanoate [(Z)-3-HP] activates defensive mechanisms, including the regulation of genes involved in
the synthesis and degradation of callose. In this study, conducted under greenhouse conditions, we tested the
hypothesis that damage caused by N. tenuis could be reduced by exposing tomato plants to (Z)-3-HP through
polymeric dispensers. Tomato plants exposed to (Z)-3-HP and non-exposed control plants were inoculated with
N. tenuis. Nesidiocoris tenuis established in both groups with no significant differences between the two treatments.
However, as hypothesized, the damage caused by N. tenuis was significantly lower in the plants exposed to
(Z)-3-HP. Gene expression analysis of salicylic, jasmonic, and abscisic acids, along with histochemical staining
methods, was used to compare the defensive responses of tomato plants infested solely with N. tenuis versus those
infested with N. tenuis and exposed to (Z)-3-HP. Our findings confirm the influence of (Z)-3-HP exposure on
differential defensive activation between treatments and reduced callose deposition in (Z)-3-HP-exposed plants.
These results pave the way for improved management of N. tenuis by enhancing the plant’s defenses based on inter-plant communication.
to its zoophytophagous behavior. When N. tenuis pierces the stems and petioles of tomato plants with its stylets, it
triggers callose deposition and subsequent cell death, resulting in blocked nutrient transport, floral abortions, or
wilting of tender shoots. Recently, it has been shown that exposure of tomato plants to the green leaf volatile (Z)-
3-hexenyl propanoate [(Z)-3-HP] activates defensive mechanisms, including the regulation of genes involved in
the synthesis and degradation of callose. In this study, conducted under greenhouse conditions, we tested the
hypothesis that damage caused by N. tenuis could be reduced by exposing tomato plants to (Z)-3-HP through
polymeric dispensers. Tomato plants exposed to (Z)-3-HP and non-exposed control plants were inoculated with
N. tenuis. Nesidiocoris tenuis established in both groups with no significant differences between the two treatments.
However, as hypothesized, the damage caused by N. tenuis was significantly lower in the plants exposed to
(Z)-3-HP. Gene expression analysis of salicylic, jasmonic, and abscisic acids, along with histochemical staining
methods, was used to compare the defensive responses of tomato plants infested solely with N. tenuis versus those
infested with N. tenuis and exposed to (Z)-3-HP. Our findings confirm the influence of (Z)-3-HP exposure on
differential defensive activation between treatments and reduced callose deposition in (Z)-3-HP-exposed plants.
These results pave the way for improved management of N. tenuis by enhancing the plant’s defenses based on inter-plant communication.
Dynamic intraguild interactions between two sympatric and congeneric coccinellid species associated with aphids could explain their coexistence in citrus agroecosystems
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Bouvet, Juan Pedro Raúl
- Urbaneja, Alberto
- Monzó, César
Scymnus interruptus and Scymnus subvillosus (Coleoptera: Coccinellidae) are the most frequent aphid predators in
Western Mediterranean citrus agroecosystems. Intraguild predation (IGP) between them would be expected, but
how IGP might affect their coexistence and biological control function remains unknown. In this work, we assess
the frequency of predator encounters in the field and investigate intraguild predation between these two
predators in laboratory settings. Different field prey scenarios derived from the field observations were simulated
with the two dominant aphid species in this agroecosystem, Aphis gossypii and Aphis spiraecola.
Scymnus subvillosus and S. interruptus engaged in IGP but the magnitude and symmetry varied with the prey
species and abundance. At high aphid densities, IGP was symmetric and weak, whereas, at low aphid densities,
IGP was strong and very asymmetric, with S. interruptus taking the role of the intraguild predator. The developmental
time of S. subvillosus was reduced when competing with S. interruptus at high extraguild prey densities.
The adult size of both predators under weak IGP also increased even when the developmental time had been
reduced.
We predict that high aphid infestations in the spring would benefit S. subvillosus, while the strong and
asymmetric IGP at low aphid infestations would hinder its coexistence with S. interruptus. Our results give a
theoretical explanation to what is observed in the field: S. subvillosus is typically dominant during the high aphid
infestations of the spring, whereas S. interruptus increases in relative dominance during the summer and fall when
aphid abundance is much less.
Western Mediterranean citrus agroecosystems. Intraguild predation (IGP) between them would be expected, but
how IGP might affect their coexistence and biological control function remains unknown. In this work, we assess
the frequency of predator encounters in the field and investigate intraguild predation between these two
predators in laboratory settings. Different field prey scenarios derived from the field observations were simulated
with the two dominant aphid species in this agroecosystem, Aphis gossypii and Aphis spiraecola.
Scymnus subvillosus and S. interruptus engaged in IGP but the magnitude and symmetry varied with the prey
species and abundance. At high aphid densities, IGP was symmetric and weak, whereas, at low aphid densities,
IGP was strong and very asymmetric, with S. interruptus taking the role of the intraguild predator. The developmental
time of S. subvillosus was reduced when competing with S. interruptus at high extraguild prey densities.
The adult size of both predators under weak IGP also increased even when the developmental time had been
reduced.
We predict that high aphid infestations in the spring would benefit S. subvillosus, while the strong and
asymmetric IGP at low aphid infestations would hinder its coexistence with S. interruptus. Our results give a
theoretical explanation to what is observed in the field: S. subvillosus is typically dominant during the high aphid
infestations of the spring, whereas S. interruptus increases in relative dominance during the summer and fall when
aphid abundance is much less.
Plant volatile-triggered defense in citrus against biotic stressors
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Pérez-Hedo, Mertixell
- Gallego-Giraldo, Carolina
- Forner-Giner, María A.
- Ortells-Fabra, Raúl
- Urbaneja, Alberto
Plants employ sophisticated defense mechanisms, including releasing volatile
organic compounds, to defend against biotic and abiotic stresses. These
compounds play a crucial role in plant defense by attracting natural enemies
and facilitating communication between plants to activate defense mechanisms.
However, there has been no research on how exposure to these compounds
activates defense mechanisms in citrus plants. To elucidate the underlying
mechanisms governing citrus defensive activation, we conducted a molecular
analysis of the rootstock Citrange carrizo [a hybrid of Citrus sinensis × Poncirus
trifoliata] in response to defense activation by the volatile (Z)-3-hexenyl
propanoate [(Z)-3-HP], utilizing a groundbreaking transcriptomic analysis
involving the genomes of both parental species. Our results revealed
significant gene expression changes, notably the overexpression of genes
related to plant immunity, antioxidant activity, defense against herbivores, and
tolerance to abiotic stress. Significantly, P. trifoliata contributed most notably to
the hybrid’s gene expression profile in response to (Z)-3-HP. Additionally, plants
exposed to (Z)-3-HP repelled several citrus pests, attracted natural predators,
and led to diminished performance of two key citrus pests. Our study emphasizes
the complex molecular basis of volatile-triggered defenses in citrus and
highlights the potential of plant volatiles in pest control strategies.
organic compounds, to defend against biotic and abiotic stresses. These
compounds play a crucial role in plant defense by attracting natural enemies
and facilitating communication between plants to activate defense mechanisms.
However, there has been no research on how exposure to these compounds
activates defense mechanisms in citrus plants. To elucidate the underlying
mechanisms governing citrus defensive activation, we conducted a molecular
analysis of the rootstock Citrange carrizo [a hybrid of Citrus sinensis × Poncirus
trifoliata] in response to defense activation by the volatile (Z)-3-hexenyl
propanoate [(Z)-3-HP], utilizing a groundbreaking transcriptomic analysis
involving the genomes of both parental species. Our results revealed
significant gene expression changes, notably the overexpression of genes
related to plant immunity, antioxidant activity, defense against herbivores, and
tolerance to abiotic stress. Significantly, P. trifoliata contributed most notably to
the hybrid’s gene expression profile in response to (Z)-3-HP. Additionally, plants
exposed to (Z)-3-HP repelled several citrus pests, attracted natural predators,
and led to diminished performance of two key citrus pests. Our study emphasizes
the complex molecular basis of volatile-triggered defenses in citrus and
highlights the potential of plant volatiles in pest control strategies.
Exclusion of ground-nesting ants promotes biological control, but facilitates the establishment of an exotic canopy-nesting ant species
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Plata, Ángel
- Gómez-Martínez, María A.
- Beitia, Francisco J.
- Tena, Alejandro
Exclusion of ground-nesting ants from tree canopies is an ant-management technique used in fruit crops. This strategy aims to disrupt the symbiotic relationship between ants and honeydew-producing herbivores, which are protected by ants, and enhance the biological control of these herbivores. Here, we evaluated this strategy to enhance the biological control of mealybugs in persimmon, but obtained an unexpected outcome. Using a randomized block design in a commercial persimmon orchard during two consecutive years, we demonstrated that physical barriers based on sticky bands excluded native ground-nesting ant species from persimmon trees and reduced the protection that these ants provided to mealybugs. The exclusion of native ground-nesting ants also increased the density and efficacy of the biological control agents of the mealybug. However, physical barriers favoured the establishment of the exotic canopy-nesting ant species Cardiocondyla obscurior. This ant species established its colonies under the sepals of persimmon fruit, and its abundance increased by more than 10 times in trees with physical barriers. Our results show that the exclusion of native ground-nesting from fruit trees can promote the control of invasive mealybugs, but may also facilitate the establishment and spread of exotic canopy-nesting ant species, hence increasing their invasive potential. Further research should evaluate alternative ant management strategies to enhance biological control of honeydew-producing herbivores without benefiting exotic canopy-nesting ant species.
Proyecto: ERDF/PCV 2021-2027/52202
Not just candy: A herbivore-induced defence-related plant protein in honeydew enhances natural enemy fitness
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Urbaneja-Bernat, Pablo
- Rodríguez-Saona, César
- Valero, M. Luz
- González-Cabrera, Joel
- Tena, Alejandro
Herbivore feeding often increases secondary metabolite production in plants. These herbivore-induced plant proteins might end up in honeydew excreted by phloem-feeding insects. This is important because honeydew is one of the most abundant and accessible carbohydrate sources for natural enemies in many agroecosystems and these proteins can thus mediate many tri-trophic interactions.
Here, we hypothesized that defensive metabolites induced in the phloem by herbivory accumulate in the honeydew excreted by phloem-feeding insects and, consequently, affect the fitness of the herbivores' natural enemies that feed on it.
We used a tri-trophic system consisting of citrus plants, the mealybug Planococcus citri and its primary parasitoid Anagyrus vladimiri. First, we assessed A. vladimiri fitness when fed on P. citri honeydew. We then collected honeydew of seven phloem-feeding insects, including P. citri, and analysed their protein content. Finally, we analysed the effect of superoxide dismutase (SOD), an antioxidant enzyme associated with plant defences that was commonly found in the analysed honeydews, on A. vladimiri fitness.
The fitness of A. vladimiri increased when fed on honeydew compared to a sucrose-based diet, demonstrating that honeydew can contain compounds that benefit natural enemies. Proteomic analyses showed that defence-related plant proteins were present in honeydew of seven phloem-feeding insects analysed. Among these, the enzyme SOD was present in honeydew of all of them. Moreover, the levels of SOD were 10-fold higher in the phloem of plants infested by P. citri than in that of uninfested plants. SOD was also actively excreted in P. citri honeydew, and we proved that it increases the fecundity of the parasitoid A. vladimiri.
We conclude that enzymatic proteins induced by herbivory in the phloem and involved in plant defence, accumulate in the honeydew excreted by phloem-feeding insects and, contrary to the current paradigm, at least some of these can have positive effects on the third trophic level.
Here, we hypothesized that defensive metabolites induced in the phloem by herbivory accumulate in the honeydew excreted by phloem-feeding insects and, consequently, affect the fitness of the herbivores' natural enemies that feed on it.
We used a tri-trophic system consisting of citrus plants, the mealybug Planococcus citri and its primary parasitoid Anagyrus vladimiri. First, we assessed A. vladimiri fitness when fed on P. citri honeydew. We then collected honeydew of seven phloem-feeding insects, including P. citri, and analysed their protein content. Finally, we analysed the effect of superoxide dismutase (SOD), an antioxidant enzyme associated with plant defences that was commonly found in the analysed honeydews, on A. vladimiri fitness.
The fitness of A. vladimiri increased when fed on honeydew compared to a sucrose-based diet, demonstrating that honeydew can contain compounds that benefit natural enemies. Proteomic analyses showed that defence-related plant proteins were present in honeydew of seven phloem-feeding insects analysed. Among these, the enzyme SOD was present in honeydew of all of them. Moreover, the levels of SOD were 10-fold higher in the phloem of plants infested by P. citri than in that of uninfested plants. SOD was also actively excreted in P. citri honeydew, and we proved that it increases the fecundity of the parasitoid A. vladimiri.
We conclude that enzymatic proteins induced by herbivory in the phloem and involved in plant defence, accumulate in the honeydew excreted by phloem-feeding insects and, contrary to the current paradigm, at least some of these can have positive effects on the third trophic level.
Proyecto: ERDF/PCV 2021-2027/52202
Intraspecific diversity of Erwinia amylovora strains from northern Algeria
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Talhi, Lina
- Barbé, Silvia
- Navarro-Herrero, Inmaculada
- Sebaihia, Mohammed
- Marco-Noales, Ester
Background Fire blight, caused by Erwinia amylovora, is the most destructive bacterial disease affecting plants in
the Rosaceae family, leading to significant economic losses. In Algeria, this disease has been reported since 2010. This
study aimed to investigate the origin of fire blight in Algeria, in order to increase knowledge of the epidemiology of
this serious disease and contribute to its management. A comprehensive characterization of 18 E. amylovora isolates
recovered from northern Algeria between 2016 and 2021 to evaluate their phenotypical and genotypical diversity
was conducted.
Results Phenotypic differences, particularly in growth kinetics, virulence, and fatty acid profiles, allowed
differentiation of strains into five groups, possibly indicating distinct introduction events. Genetic characterization
revealed that only one strain lacked the ubiquitous plasmid pEA29, which is correlated with reduced virulence, while
none harbored the pEI70 plasmid. Phylogenetic analysis using concatenated sequences of the recA, groEL, rpoS, ams,
and hrpN genes grouped Algerian strains with those from a broadly prevalent clade. CRISPR genotyping identified a
novel CR1 pattern and three genotypes, two of them previously unreported.
Conclusions This study represents the first phenotypic, genetic, and phylogenetic investigation of E. amylovora
strains in the region, and provides valuable information on the possible pathways of the introduction of this fire blight
pathogen in northern Africa. The findings suggest one or more introduction events from a common ancestor, likely
originating in northern Italy, followed by dispersal in various regions of Algeria.
the Rosaceae family, leading to significant economic losses. In Algeria, this disease has been reported since 2010. This
study aimed to investigate the origin of fire blight in Algeria, in order to increase knowledge of the epidemiology of
this serious disease and contribute to its management. A comprehensive characterization of 18 E. amylovora isolates
recovered from northern Algeria between 2016 and 2021 to evaluate their phenotypical and genotypical diversity
was conducted.
Results Phenotypic differences, particularly in growth kinetics, virulence, and fatty acid profiles, allowed
differentiation of strains into five groups, possibly indicating distinct introduction events. Genetic characterization
revealed that only one strain lacked the ubiquitous plasmid pEA29, which is correlated with reduced virulence, while
none harbored the pEI70 plasmid. Phylogenetic analysis using concatenated sequences of the recA, groEL, rpoS, ams,
and hrpN genes grouped Algerian strains with those from a broadly prevalent clade. CRISPR genotyping identified a
novel CR1 pattern and three genotypes, two of them previously unreported.
Conclusions This study represents the first phenotypic, genetic, and phylogenetic investigation of E. amylovora
strains in the region, and provides valuable information on the possible pathways of the introduction of this fire blight
pathogen in northern Africa. The findings suggest one or more introduction events from a common ancestor, likely
originating in northern Italy, followed by dispersal in various regions of Algeria.
Proyecto: ERDF/PCV 2021-2027/52202
Enhancing tomato crop resilience to water stress: the role of Trichoderma afroharzianum T22 and Nesidiocoris tenuis management
ReDivia Repositorio Digital del Instituto Valenciano de Investigaciones Agrarias
- Urbaneja, Alberto
- Ortells-Fabra, Raúl
- Pérez-Hedo, Mertixell
Global warming substantially threatens agricultural systems worldwide, with specific consequences for tomatoes,
such as increased water demands and heightened pest pressures. Adopting sustainable farming practices is imperative, and
Trichoderma species emerge as a valuable tool that enhances tomato growth, pest resilience, and stress tolerance. The integration
of this approach into existing Integrated Pest Management (IPM) strategies requires careful consideration. A paradox
arises in Southern Europe, where tomato cultivation heavily relies on predatory mirid bugs, especially Nesidiocoris tenuis,
for pest control. While N. tenuis effectively controls tomato pests, it can also harm plants by inducing callose deposits,
wilting, and yield losses, mainly when prey availability is scarce. This study delves into critical questions surrounding the
concurrent use of T. afroharzianum T-22 and N. tenuis in tomato crops under water stress. We employed a randomized block
design to examine three key factors: 1) varying levels of water stress, 2) the presence or absence of T. afroharzianum T-22
inoculation, and 3) the release or non-release of N. tenuis. Our findings demonstrate that T. afroharzianum T-22 enhances
tomato growth under water stress and mitigates the adverse impact of N. tenuis on plant development. Additionally, T. afroharzianum
T-22 inoculation did not affect N. tenuis performance, but it did reduce oxidative stress caused by N. tenuis, thus
diminishing the plant damage attributed to this predatory mirid. These results hold significance for advancing pest management
and promoting sustainable horticulture in a world grappling with the challenges of a warming climate
such as increased water demands and heightened pest pressures. Adopting sustainable farming practices is imperative, and
Trichoderma species emerge as a valuable tool that enhances tomato growth, pest resilience, and stress tolerance. The integration
of this approach into existing Integrated Pest Management (IPM) strategies requires careful consideration. A paradox
arises in Southern Europe, where tomato cultivation heavily relies on predatory mirid bugs, especially Nesidiocoris tenuis,
for pest control. While N. tenuis effectively controls tomato pests, it can also harm plants by inducing callose deposits,
wilting, and yield losses, mainly when prey availability is scarce. This study delves into critical questions surrounding the
concurrent use of T. afroharzianum T-22 and N. tenuis in tomato crops under water stress. We employed a randomized block
design to examine three key factors: 1) varying levels of water stress, 2) the presence or absence of T. afroharzianum T-22
inoculation, and 3) the release or non-release of N. tenuis. Our findings demonstrate that T. afroharzianum T-22 enhances
tomato growth under water stress and mitigates the adverse impact of N. tenuis on plant development. Additionally, T. afroharzianum
T-22 inoculation did not affect N. tenuis performance, but it did reduce oxidative stress caused by N. tenuis, thus
diminishing the plant damage attributed to this predatory mirid. These results hold significance for advancing pest management
and promoting sustainable horticulture in a world grappling with the challenges of a warming climate
The Dual Benefit of Plant Essential Oils against Tuta absoluta
RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
- Ben Abdallah, Saoussen
- Riahi, Chaymaa
- Vacas, Sandra|||0000-0001-6911-1647
- Navarro-Llopis, Vicente|||0000-0003-3030-3304
- Urbaneja, Alberto
- Pérez-Hedo, Meritxell
[EN] Plant essential oils (PEOs) are being studied as a potential alternative to synthetic pesticides in agriculture. PEOs have the potential to control pests both directly, by being toxic or repellent to pests, and indirectly, by activating plant's defense mechanisms. In this study, the effectiveness of five PEOs (Achillea millefolium, Allium sativum, Rosmarinus officinallis, Tagetes minuta, and Thymus zygis) on controlling Tuta absoluta and their impact on the predator Nesidiocoris tenuis was examined. The study revelead that PEOs from A. millefolium and A. sativum-sprayed plants significantly reduced the number of T. absoluta-infested leaflets and did not affect the establishment and reproduction of N. tenuis. Additionally, the spraying of A. millefolium and A. sativum increased the expression of defense genes in the plants, triggering the release of herbivory-induced plant volatiles (HIPVs), such as C6 green leaf volatiles, monoterpenes, and aldehydes, which can be messengers in tritrophic interactions. The results suggest that PEOs from A. millefolium and A. sativum can provide a dual benefit for controlling arthropod pests, as they can directly exhibit toxicity against these pests while also activating plant defense mechanisms. Overall, this study provides new insights into using PEOs as a sustainable solution for controlling pests and diseases in agriculture, by reducing synthetic pesticides and promoting the use of natural predators., This work was partially supported by the project ASTER from Call Prima Section 2 2021-Multi-Topic, by grant PID2020-113234RR-I00 from the Spanish Ministerio de Ciencia e Innovacion through the Agencia Estatal de Investigacion (co-financed European Regional Development Fund, ERDF) and by grant IVIA-52202B from Instituto Valenciano de Investigaciones Agrarias (this project is susceptible of being co-financed by the European Union through the ERDF Operational Program). C.R. was supported by a Ph.D. contract from MCIN (PRE2018-084631). S.B.A. was a visiting Postdoc at IVIA, supported by the Ministry of Higher Education and Scientific Research of Tunisia.
Enhancing tomato crop resilience to water stress: the role of Trichoderma afroharzianum T22 and Nesidiocoris tenuis management
RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
- Urbaneja, Alberto
- Ortells-Fabra, Raul
- Pérez-Hedo, Meritxell
[EN] Global warming substantially threatens agricultural systems worldwide, with specific consequences for tomatoes, such as increased water demands and heightened pest pressures. Adopting sustainable farming practices is imperative, and Trichoderma species emerge as a valuable tool that enhances tomato growth, pest resilience, and stress tolerance. The integration of this approach into existing Integrated Pest Management (IPM) strategies requires careful consideration. A paradox arises in Southern Europe, where tomato cultivation heavily relies on predatory mirid bugs, especially Nesidiocoris tenuis, for pest control. While N. tenuis effectively controls tomato pests, it can also harm plants by inducing callose deposits, wilting, and yield losses, mainly when prey availability is scarce. This study delves into critical questions surrounding the concurrent use of T. afroharzianum T-22 and N. tenuis in tomato crops under water stress. We employed a randomized block design to examine three key factors: 1) varying levels of water stress, 2) the presence or absence of T. afroharzianum T-22 inoculation, and 3) the release or non-release of N. tenuis. Our findings demonstrate that T. afroharzianum T-22 enhances tomato growth under water stress and mitigates the adverse impact of N. tenuis on plant development. Additionally, T. afroharzianum T-22 inoculation did not affect N. tenuis performance, but it did reduce oxidative stress caused by N. tenuis, thus diminishing the plant damage attributed to this predatory mirid. These results hold significance for advancing pest management and promoting sustainable horticulture in a world grappling with the challenges of a warming climate., The authors would like to thank Chara Vatsa (Erasmus student from the Agricultural University of Athens, Greece) , Beatriz Granero-Garcia, Pedro Morales-Amezcua, Teresa Perez-Domingo and Jose Ignacio Martinez-Paredes (IVIA) for their assistance in conducting the experiments, and Dr. Oscar Molla (IVIA) for data analysis. His work was partially supported by the project ASTER from Call Prima Section 2 2021 - Multi-Topic, by grant PID2020-113234RR-I00 from the Spanish Ministerio de Ciencia e Innovacion through the Agencia Estatal de Investigacion (co-financed European Regional Development Fund, ERDF) and by grant IVIA-52202F from Instituto Valenciano de Investigaciones Agrarias (IVIA) from Generalitat Valenciana (GVA) (this project is susceptible of being co-financed by the European Union through the ERDF Operational Program) . R.O.-F. was supported by a Ph.D. contract from MCIN (PRE2021-100879) .
Response of Amblyseius swirskii to deltamethrin
RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
- Benavent-Albarracín, Luis
- Pérez-Hedo, Meritxell
- Alonso-Valiente, Miquel
- Catalán, José
- Urbaneja, Alberto
- González-Cabrera, Joel
[EN] BACKGROUND The rising demand for environmentally friendly pest control highlights the importance of understanding the interaction between natural enemies and pesticides. Amblyseius swirskii, a predatory mite extensively used in biocontrol, plays a crucial role in managing pest populations in agricultural systems. Integrating this mite with selective pesticide use within integrated pest management (IPM) would significantly advance pest control and may reduce pesticide residues in the environment and agricultural produce. This study characterized the susceptibility of two Amblyseius swirskii colonies to deltamethrin, a widely used pesticide, to assess their potential integration into IPM strategies.
RESULTS Both colonies exhibited significant tolerance to deltamethrin at concentrations higher than the maximum recommended field rate. Our analysis identified mutations in the target site in both populations. The commercial population also showed a contribution of cytochromes P450 to the resistant phenotype. Despite these results, semi-field trials revealed a significant reduction in mite counts post-treatment with deltamethrin; various experiments were conducted to understand this discrepancy.
CONCLUSION This study underscores the need for comprehensive evaluations of pesticide impacts on biological control agents to optimize IPM strategies. Understanding pesticide resistance and field performance dynamics is crucial for developing sustainable pest management practices that ensure environmental resilience and agricultural productivity., LB-A was recipient of a PhD grant by the Spanish Ministry of Economy and Competitiveness (BES-2016-077086). The work at the Universitat de Valencia was funded by MCIN/AEI/10.13039/501100011033/FEDER, EU, grant PID2022-140432OB-I00, where as Conselleria d'Agricultura, Pesca i Alimentacio of Generalitat Valenciana funded the work at IVIA through the project SOSTENIBLE (IVIA-52202B; this project is susceptible of being co-financed by the European Union through the FEDER Operational Program).
RESULTS Both colonies exhibited significant tolerance to deltamethrin at concentrations higher than the maximum recommended field rate. Our analysis identified mutations in the target site in both populations. The commercial population also showed a contribution of cytochromes P450 to the resistant phenotype. Despite these results, semi-field trials revealed a significant reduction in mite counts post-treatment with deltamethrin; various experiments were conducted to understand this discrepancy.
CONCLUSION This study underscores the need for comprehensive evaluations of pesticide impacts on biological control agents to optimize IPM strategies. Understanding pesticide resistance and field performance dynamics is crucial for developing sustainable pest management practices that ensure environmental resilience and agricultural productivity., LB-A was recipient of a PhD grant by the Spanish Ministry of Economy and Competitiveness (BES-2016-077086). The work at the Universitat de Valencia was funded by MCIN/AEI/10.13039/501100011033/FEDER, EU, grant PID2022-140432OB-I00, where as Conselleria d'Agricultura, Pesca i Alimentacio of Generalitat Valenciana funded the work at IVIA through the project SOSTENIBLE (IVIA-52202B; this project is susceptible of being co-financed by the European Union through the FEDER Operational Program).