Integrated pest management against Scaphoideus titanus: MICOTI project and fungal-based strategies

The leafhopper Scaphoideus titanus is the main vector of the EU quarantine pest "Candidatus Phytoplasma vitis", which is associated with the Flavescence dorée disease in grapevine. S. titanus is currently present in ten grape-growing EU member states, including Italy, and a further spread in Europe is predicted for the next years. In face of such a threat, winegrowers are likely to respond with more intense insecticidal treatments, which not only have a significant economic impact, but also harmful consequences for health and environment. For this reason, recent European regulations insist on the urgency of minimizing the use of chemicals. In this direction, the project ‘MICOTI – Fungal agents for the biocontrol of S. titanus’, proposes two complementary sustainable approaches that may lay the basis for the development of new strategies of integrated pest management against S. titanus. Both are based on insect-fungal interactions: one explores the potential application of naturally occurring entomopathogenic fungi (EPF) as biocontrol agents against the insect whereas the other is based on the possibility of using RNA interference (RNAi) mechanisms against the yeast-like symbiont of S. titanus (StYLS). EPF strains will first be selected based on their pathogenicity through direct contact with S. titanus. Additionally, these strains will be tested for their ability to spread and persist in the leaf tissues of grapevine. MICOTI will then evaluate whether EPF in the endophytic state have detrimental effects on S. titanus, both directly, i. e., EPF propagules come into contact with the stylet of the sap-sucking insect, and indirectly, i. e., EPF modify the plant metabolism so that it could result less attractive or suitable for the insect. Furthermore, one of the main achievements of the project will be the definition of the StYLS metabolic potential and the identification of the critical aspects of the symbiosis with S. titanus. Through the genomic, proteomic, and biodiversity characterization of StYLS, MICOTI will add new information about the role of endosymbiotic fungi within the insect microbiota and their adaptation to the endosymbiotic lifestyle. The fungal genes related to the metabolic pathways that will be identified as essential for the insect survival will be the primary targets for RNAi-mediated silencing. In this way, MICOTI will explore for the first time the possibility to interfere with the gene expression of a fungal endosymbiont to perturb the fitness of its insect host. MICOTI project therefore intends to contribute to the development of sustainable, safe and healthy viticulture.