Scientists from the EU-funded BeXyl project aimed to address key knowledge and operational gaps in the risk assessment and management of Xylella fastidiosa, to develop effective, economically and socially feasible IPM schemes ready for implementation.
Context
Xylella fastidiosa is one of the most threatening plant pathogens worldwide. The biology and epidemiology of X. fastidiosa associated diseases pose important limitations for laboratory and field studies, making the development and evaluation of disease management strategies particularly challenging. Over the years, many solutions that seemed promising under controlled conditions proved far less effective when tested in field conditions. The experience gained by the BeXyl project partners highlighted the need for integrating science-based strategies to effectively manage X. fastidiosa in real European production contexts.
First, be prepared
Thanks to BeXyl, researchers developed an integrated modelling framework to support risk assessment and predict how the X. fastidiosa epidemics may evolve under different environmental conditions. These models also support a prompt and effective response to the emergence of new outbreaks.
The framework includes several models that can be used in a complementary way. In particular, the following were developed:
- A demographic model describing the population dynamics of the main European vector, Philaenus spumarius, predicting its phenology and population abundance based on local weather conditions throughout the year;
- A detailed eco-epidemiological model describing the epidemiological dynamics of Xylella fastidiosasubsp. pauca in olive groves, allowing to define the role of the different processes (pathogen population growth, vector-host interaction and pathogen transmission) in the infection and disease progression as function of environmental conditions. The model also enables the comparative evaluation of different control strategies;
- A simplified epidemiological model that focus in particular on the role of vector host preferences for different host plants in pathogen transmission and disease dynamics in olives;
- A model describing the infection dynamics in grapevine driven by temperature and host plant phenology. A similar model is currently being developed for almond crops.
Together, these tools allow to simulate disease and vector population dynamics, and transmission processes under varied environmental conditions, supporting the development of targeted and effective control strategies.
Cultivating resilience
Field experiments conducted within the BeXyl project provided new insights on how disease progresses in olive groves and helped identify useful practices for managing tolerant and resistant cultivars, improving the resilience of olive production. Researchers monitored naturally infected olive groves characterized by different plant densities, vectors abundance, and ground cover management strategies, assessing:
- Disease progression through regular visual inspections using symptom rating scales from 0 (no symptoms) to 5 (severe symptoms);
- Infection prevalence and distribution within the canopy (basal vs apical parts) through systematic plant sampling and molecular diagnostic analyses (qPCR).
Testing biological solutions against the vector
Controlling insect vectors is a key element in the fight against X. fastidiosa. Two large-scale field trials were launched in Apulia, Italy, to evaluate the efficacy of entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, against the juvenile stages of the spittlebugs P. spumarius and Neophilaenus campestris.
These ongoing trials aim to validate sustainable biological solutions, and the obtained results will allow the project to identify innovative options to reduce reliance on synthetic insecticides and support the integration of low-impact control tools for vector management.
Testing biological solutions against Xylella fastidiosa
BeXyl partners have also established a network of experimental fields in Southern Italy and Mallorca, Spain, to test new microbiological solutions developed in the project to improve plants responses to infection. Specifically, they tested:
- Peptide-based antibiotics on almond;
- Bacteriophages (phages) on grapevine;
- Synthetic microbial consortia (SynComs, laboratory-created communities of beneficial microorganisms) on olive.
These experiments evaluate how these solutions perform against different Xylella fastidiosa subspecies and assess their effectiveness, sustainability, and possible integration into disease management strategies.
Towards effective and sustainable IPM schemes
The results generated within the BeXyl project are being used to develop IPM schemes adapted to different X. fastidiosa epidemiological scenarios for almond, grapevine and olive crops in Europe, considering not only the agronomic challenges but also the socio-economic context.
After selecting and assessing the available options developed by BeXyl and other existing options that seek to mitigate disease spread, researchers analysed the environmental conditions, farming practices, and social-economic drivers that may influence the adoption of IPM solutions on the farm. Based on this work, they prepared a list of candidates IPM protocols and selected the most sustainable and effective schemes.
The schemes will be integrated into a user-oriented Decision-Support System (DSS), which will be made available by the end of the project. The DSS will provide tailored guidance and structured information to help farmers, nurseries, and plant health authorities select and implement appropriate IPM strategies for managing X. fastidiosa in Europe.
Xylella fastidiosa
Xylella fastidiosa is one of the most threatening plant pathogens worldwide, capable of colonising more than 700 plant species. It causes diseases responsible for agricultural and environmental losses amounting to millions of dollars in the United States and Brazil. In October 2013, the bacterium was detected for the first time in the EU, on olive trees in the Apulia region of southern Italy. Since then, outbreaks have also been reported in France, Spain and Portugal.
Further information is available at: https://www.efsa.europa.eu/en/topics/topic/xylella-fastidiosa
Fonte: BeXyl – Beyond Xylella
