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Biocontrol of Xylella and its vector in olive trees for integrated pest management

Periodic Reporting for period 3 - BIOVEXO (Biocontrol of Xylella and its vector in olive trees for integrated pest management)

Reporting period: 2022-05-01 to 2023-10-31

Xylella fastidiosa is a pathogenic bacterium being transmitted by xylem-feeding insects, mainly spittlebugs Philaenus spumarius in the Mediterranean region. This pathogenic bacterium causes diseases on olive, other fruit trees and other various crops whilst also being present in different host plants. In addition to damaging almond trees in in Spain, Xylella has cause severe damage to olive trees in Spain and Italy and since its first detection in 2013. In particular in Apulia, olive production has already collapsed by 65-80% and approximately 100,000 jobs have been lost including jobs on farms and the farm supply sector. Yield losses of 35-70% in olive harvests are projected by European Food Safety Authority (EFSA) in case of Xylella spreading to all olive regions in Europe.

No biopesticides are currently registered against Xylella and in many cases, farmers must destroy infected trees which can lead to total abandoning of farms and olive plantations of high economical, societal and cultural heritage value.
To fight against Xylella, BIOVEXO develops both Xylella-targeting biopesticides (X-biopesticides) for use on the plants, as well as biopesticides combatting the insect vectors (V-biopesticides) which transmit the bacterium.

The BIOVEXO biopesticides should help achieve:
i) Reduction of Xylella pressure and disease severity in olive cultivation, while also protecting the environment;
ii) Protection and safeguarding of the long-established olive orchards as traditional landscape elements in Mediterranean cultural heritage;
iii) Prevention of Xylella infections in new olive plantations and;
iv) Security and sustainability of jobs in disease-affected areas and the continuity of olive and almond cultivation.

BIOVEXO aims to make the biopesticides ready for commercial use in integrated pest management soon after project completion.
BIOVEXO performed 3 years of field trials in olive plantations in Apulia, Alicante and Mallorca, and on almond trees in Mallorca. After 3 years, the results are promising but more field trials are needed to prove the efficacy.

Based on results from initial (small scale) field trials, promising X- and V-biopesticides have been selected for large scale field trials. These X- and V-biopesticides consist of a bacterial endophyte and two plant extracts. The trials distinguish between curative and preventive treatments, which aim to be combined to achieve an integrated pest management (IPM) to control both the pathogenic bacterium and the vector.

Preventive trials were being carried out on newly planted olives or young almonds of susceptible cultivars, while curative trials are being performed on already infected plants. The presence of Xylella infections on olives to be subjected to curative treatments has been ascertained by preliminary qPCR as well as the presence of symptoms.

Improved formulations and tests of different modes of inoculation are needed to increase efficacy of the biopesticides. Consequently, more small- and large-scale field trials are needed for evaluation of efficacy.

Main achievements:
• The optimal formulation and application conditions for X-biopesticide endotherapy have been established; nonetheless, the treatment's lack of efficacy led to the decision to halt the endotherapy trials.
• Upscaling production and optimisation of formulation on an industrial scale
• Plant defence reactions were analysed and progress was achieved on plant colonization
• Final selection of the olive and almond orchards for large scale WP4 field trials in Apulia and Spain
• Plantation of new olives of the susceptible olive cultivar to implement preventive trials integrating X- and V-biopesticides already started in Apulia
• Design of an integrated pest management strategy targeting Xylella fastidiosa and its vector P. spumarius for trials in Apulia
• Selection of 2 X- biopesticides and 1 V-biopesticide
• Definition of a mode and frequency of application of biopesticides
• Observed a slowdown of the Xylella symptoms progression on the canopies on the plants treated by X-biopesticides as well as a reduction of the juvenile and adult populations of P. spumarius by a V-biopesticide.
BIOVEXO is developing innovative approaches using plant-colonising (systemic) microorganisms and plant by-product that may also reach inner plant tissues to directly counteract Xylella. BIOVEXO is also developing innovative bio-based vector-targeting control products involving microbial strains, plant extracts and microbial metabolites that are tested in different soil, climate and cultivation conditions. These biopesticides are developed for best application ensuring suitable formulation, efficacy and adequate uses of feedstock resources in order to develop sustainable and control solutions with the aim to have market-ready products by, or shortly after project completion.

BIOVEXO planned to make environmental, economic and socio-economic impacts, which remain valid the full duration of the project.

The project aims to reduce the environmental footprint associated with agricultural activities as compared with existing alternative approaches and to increase the overall resource efficiency. BIOVEXO will continue to optimise and develop new X- and V-biopesticides based on plant extracts or microorganisms. These biopesticides will be close to market entry at the end of the project and will be used as solutions for a sustainable approach, aimed at preserving diversity and involving circular economy.

Increasing crop yield by at least 10% as compared with existing cultivation cases based on chemical inputs, reducing costs of crop (nutrition and) control by 15% as compared with benchmark chemical approaches, and increasing income and business opportunities for stakeholders and actors in the bio-based sectors, in particular in the primary sectors.

Creating new job opportunities in the bio-based sector, particularly the rural areas by protecting olive and almond trees as well as by increasing job opportunities in the industrial sector. BIOVEXO will also aim to make an impact in education through trainings and workshops in order to raise awareness on Xylella and increase understanding of bio-based economy in the society. Raising awareness and educating wider audience is also expected to be done through scientific publications and scientific conferences BIOVEXO will organise and/or partake in. Synergies with regional initiatives in Apulia, Mallorca and Valencia are also expected, as well as the possibility of supporting the regional development by diversifying the local economy.

The BIOVEXO project will provide understanding of the biopesticides‘ mode of action to support final product development. Above all, the project aims to ensure continued olive and almond cultivation, reducing the use and risk of harmful pesticides, as well as reducing the socio-economic pressures of Xylella and disease severity in olive cultivation. BIOVEXO will potentially impact the protection and safety of long-established olive orchard with socio-cultural value (with 1,500 year-old trees) and ensure prevention of future spread of Xylella infections to secure and sustain jobs in severely affected areas. Finally, it is important to highlight that BIOVEXO aims to make a significant impact in protecting global plant health, securing fragile ecosystems and ensuring environmental and economic sustainability.
25 years old olive trees used in preventive treatments in Apulia (Cellina di Nardo orchard)
BIOVEXO hands-on Field Trials investigating young olive tree in field trial in Mallorca
Experimental trials for the curative treatments. 8 (a) and 20 Apulia