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 massive dieback of olive trees, and is threatening olive production throughout the Mediterranean Region. The key vector of X. fastidiosa in Europe is the spittlebug Philaenus spumarius L. The dispersal capabilities of P. spumarius are poorly known, despite being a key parameter for the prediction of the spread of the bacterium. In this study, we have examined the dispersal of P. spumarius adults in two different agroecosystems in Italy: an olive grove in Apulia (Southern Italy) and a meadow in Piedmont (Northern Italy). Insects were marked with albumin and released during seven independent trials over 2 yr. The recapture data were pooled separately for each agroecosystem and used to estimate the dispersal kernels of P. spumarius in the olive grove and in the meadow. The diffusion coefficient estimate for P. spumarius was higher in the meadow than in the olive grove. The median distance from the release point for 1 d of dispersal was 26 m in the olive grove and 35 m in the meadow. On the basis of our model, we estimated that 50% of the spittlebug population remained within 200 m (98% within 400 m) during the 2 mo period of high abundance of the vector on olives in Apulia. The dispersal of P. spumarius is thus limited to some hundreds of meters throughout the whole year, although it can be influenced to a great extent by the structure of the agroecosystem.