Potential impact of vector-borne phytoplasma spillovers and large-scale future study
Centuries of homogenization of agricultural production systems led to decreased genetic and species diversity of crops. Such general biological depletion was previously associated with increased pathogen outbreaks and serious economic losses in agroecosystems (Newton, 2016; King & Lively, 2012). Earlier research recognized the role of wildlife as natural reservoirs where infections are often asymptomatic. The onslaught of emerging infectious diseases in crops often involved alternative sources of inoculum and creation of new ecological interfaces, and global changes (e.g., land use or climate warming) set the stage for new associations to occur. Spillover events from natural habitats in direct contact with cultivated fields have been documented for several plant pathogens (McCann, 2020; Brooks et al., accepted), and the involvement of vectors may facilitate host shifts, accelerating the spread of diseases at the regional level. The phytoplasmas associated with Flavescence dorée disease, and related strains, (FDp) represent one of the most well-studied pathosystems (Malembic-Maher et al., 2020), providing a good example of spillover from wild plants to a crop (Vitis vinifera ) through efficient insect vectors (Trivellone & Dietrich 2020; Brooks et al., accepted). For other phytoplasma pathosystems, epidemiological information and characterization of strains associated with crops have accumulated for over forty years. However, information on genetic diversity, the range of hosts and ecological characteristics of the spreading of phytoplasmas in natural habitats are still broadly missing. This gap of knowledge hinders basic understanding of the evolution of phytoplasmas in association with their hosts, and hampers the implementation of proactive measures to cope with emerging pathogens.