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

Joao R S Lopes,Alberto Fereres,Blanca B Landa

doi:10.5424/sjar/2014123-5613

Abstract

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.

Highlights

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
Several pathogenic variants of the bacterium have been described, that are often host specific, and that have been given the category of subspecies (Schaad et al, 2004): (i) Xylella fastidiosa subsp. fastidiosa including strains from cultivated grape, alfalfa, almond, and maple; (ii) X. fastidiosa subsp. multiplex, including strains isolated from peach, elm, plum, pigeon grape, sycamore and almond; (iii) X. fastidiosa subsp. pauca, including strains isolated from citrus and coffee; and (iv) X. fastidiosa subsp. sandyi, including strains isolated from Nerium oleander
Potential vectors of Xylella fastidiosa in Spain domly selected in each region and were sampled by yellow sticky cards (10 × 30 cm) in ten vineyards located across 100 km in the Montilla-Moriles Denomination of Origin (Córdoba, Andalucía) and three vineyards distant 10-15 km apart in the Jumilla Denomination of Origin (Murcia)