dc.description.abstract | “Flavescence dorée” (FD) outbreaks in Serbian vineyards first emerged in the
early 2000s and were directly correlated with dense populations of the North
American insect vector Scaphoideus titanus. The FD phytoplasma associated
with the disease was first treated as alien and introduced, like it happens for
its insect vector. However, the genetic peculiarities of FD phytoplasma strains
from Serbia, as well as their occurrence in native alder trees in riparian areas
and clematis plants in vineyard surroundings and in natural habitats, proved
otherwise. Molecular data on the ecological properties of epidemiological
cycles driving the epidemic outbreaks of FD in Serbia today indicated the
importance of alders as reservoir plants for the epidemics (Krstić et al., 2022).
Riparian habitats hosting alder trees, alongside wild Vitis, Salix sp., clematis,
tree of heaven, and other FD phytoplasmas reservoir plants, were screened for
native leafhopper vectors as well as for Orientus ishidae, a newly established
vector of Asian origin in Serbia (Cvrković et al., 2021). Leafhopper Allygus
modestus and A. mixtus were commonly found in association with alders
in many sites, with the former being the dominant species. An established
population of O. ishidae feeding on alders was found in a single location of
riparian habitat in eastern Serbia. Among the analyzed leafhopper specimens,
using epidemiologically informative map gene typing, nearly all A. modestus
individuals were found carrying FD or -related phytoplasmas, while nearly
50% of O. ishidae were found infected at the same location. However,
A. modestus specimens had a lower phytoplasma load (Cq > 25) than O. ishidae
(Cq < 20 in 50% of infected individuals), even though they were collected in
the same period of the year. When comparing the map genotypes carried
by each of the putative vector species, A. modestus most often carried AldY genotypes, while O. ishidae was dominantly found harboring FD phytoplasma
genotypes of both Map-FD1 and FD2 clusters. The experimental verification
of the transmission capability and role in FD phytoplasma epidemiology for
each of the leafhopper species is under study. | sr |