Main insect vectors of Xylella fastidiosa in Italy and worldwide

In 2013 was detected, isolated and confirmed the bacterium Xylella fastidiosa in olive trees, oleander and almond in south-eastern Italy as the first record in the European Union. Pathogenetic tests confirmed the bacterium responsibility for a new disease: the olive quick decline syndrome (OQDS or CoDiRO). The disease is lethal, and knowledge of the candidate and actual X. fastidiosa vectors are crucial for a correct risk assessment of this threat. The xylem sap-sucking insect species present in Europe are seven sharpshooters (Cicadellidae, Cicadellinae), twenty-six spittlebugs (Aphrophoridae), seven Cercopidae, fifty-four cicadas (Cicadidae and Tibicinidae). Of these, only two species were considered potential vectors of the bacterium in Europe, Philaenus spumarius (L.) and Cicadella viridis (L.). Surveys over the infected or diseased olive groves found three homopteran species positive to X. fastidiosa. Namely, two species belonging to Aphrophoridae: P. spumarius and Neophilaenus campestris Fallén and one species of Cicadellidae: Euscelis lineolatus Brullé. Transmission tests with insects collected in infected olive groves showed the ability of P. spumarius to acquire and transmit the bacterium among olive trees and other host plants. By the time, P. spumarius is the only vector of X. fastidiosa in Europe. On-going studies will help understand the role of other candidate xylem-sap feeders vector species in the spread of the pathogenic bacterium.