A survey of potential insect vectors of the plant pathogenic bacterium Xylella fastidiosa in three regions of Spain

The emergence of a rapid-spreading olive disease associated with Xylella fastidiosa in southern Italy represents a
high risk to susceptible crops in other countries of the Mediterranean basin, if insect vectors occur in the region. The
goal of this study was to identify xylem-feeding Auchenorrhyncha that could potentially act as vectors of X. fastidiosa
in three regions of Spain (Andalucía, Murcia and Madrid). Samplings with sweep net and stem tap were carried out
in October/2004 on grapevines and adjacent crops (olives, nectarine, citrus, Prunus spp.), ornamental trees and
herbaceous weeds. Yellow sticky cards were placed in ten vineyards located across 100 km in Andalucía and in three
vineyards distant 10-15 km apart in Murcia. Specimens of frequently-trapped species were tested by nested- or
multiplex-PCR for the presence of X. fastidiosa. The Typhlocybinae leafhopper, Austroasca (Jacobiasca) lybica
(Hemiptera: Cicadellidae) was the most abundant species in vineyards and citrus orchards. Planthoppers (Hemiptera:
Fulgoroidea) and psyllids (Hemiptera: Psylloidea) were prevalent on olives. Cicadellinae leafhoppers (known as
sharpshooters), which are major vectors of X. fastidiosa in the Americas, were not found in the samples. The only
potential vectors were spittlebugs (Hemiptera: Cercopoidea) collected on Populus sp., herbaceous and on conifer trees
(Pinus halepense); the spittlebug Neophileanus sp. was common on conifer trees adjacent to a vineyard in Jumilla.
None of the insect samples tested positive for X. fastidiosa by PCR assays. However, spittlebugs already associated
with susceptible crops in Spain may allow fast spread of X. fastidiosa in case this pathogen is introduced