Agroforestry Spread of Xylella fastidiosa in Minorca: Vectors, Hosts, and Dynamics in Wild Olive Woods and Pastures

Understanding the spread of Xylella fastidiosa (XF) in agroforestry systems is key to reducing its ecological and economic impact. In Minorca (Balearic Islands), the subspecies multiplex (ST81) was detected for the first time in 2017, mainly affecting wild olive (Olea europaea var. sylvestris), a key species in Mediterranean shrublands. This study analyzes XF dynamics and its insect vectors, Philaenus spumarius (PS) and Neophilaenus campestris (NC), over three years (2019–2021) in six agroecosystems. A total of 621 Auchenorrhyncha specimens were collected and analyzed by qPCR. XF was detected in 11.88% of PS but not in NC. PS was predominantly captured on herbaceous cover and Pistacia lentiscus and less often on wild olive and Rhamnus alaternus. Infection rates in PS peaked in summer and autumn, reaching over 50% in some months, especially on wild olives. XF was also confirmed in wild olive in all plots, with infection rates between 10% and 55%. No phytoplasmas were found. These results highlight the major role of PS in XF transmission in Minorca, with wild olive as a key reservoir. The findings stress the importance of vector behavior, host plants, and landscape structure in managing XF in Mediterranean agroforestry systems, indicating migration to woody hosts as a key factor.