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.