Dispersal of Philaenus spumarius (Hemiptera: Aphrophoridae), a Vector of Xylella fastidiosa, in Olive Grove and Meadow Agroecosystems

The introduction of the Xylella fastidiosa Wells bacterium into Apulia (South Italy) has caused the massivedieback of olive trees, and is threatening olive production throughout the Mediterranean Region. The key vectorof X. fastidiosa in Europe is the spittlebug Philaenus spumarius L. The dispersal capabilities of P. spumarius arepoorly known, despite being a key parameter for the prediction of the spread of the bacterium. In this study, wehave examined the dispersal of P. spumarius adults in two different agroecosystems in Italy: an olive grove inApulia (Southern Italy) and a meadow in Piedmont (Northern Italy). Insects were marked with albumin and releasedduring seven independent trials over 2 yr. The recapture data were pooled separately for each agroecosystemand used to estimate the dispersal kernels of P. spumarius in the olive grove and in the meadow. The diffusioncoefficient estimate for P. spumarius was higher in the meadow than in the olive grove. The median distance fromthe release point for 1 d of dispersal was 26 m in the olive grove and 35 m in the meadow. On the basis of ourmodel, we estimated that 50% of the spittlebug population remained within 200 m (98% within 400 m) during the 2mo period of high abundance of the vector on olives in Apulia. The dispersal of P. spumarius is thus limited to somehundreds of meters throughout the whole year, although it can be influenced to a great extent by the structure ofthe agroecosystem.