Dispersal of Philaenus spumarius, vector of Xylella fastidiosa, in olive grove and meadow agroecosystems

The meadow spittlebug Philaenus spumarius plays the major role in the spread of X. fastidiosa subsp. pauca ST53 on olives in the Apulia region (Italy). Despite the vector’s movement is a key component of X. fastidiosa epidemiology, little information is available. Dispersal capabilities of the meadow spittlebug were hence investigated by mark-release-recapture (MRR) experiments carried out from May to October in olive grove and meadow, in the Apulia and the Piedmont regions (Italy), respectively. Field-collected adults of P. spumarius were marked with an aqueous solution of albumin (10%) and released at a single point in the centre of the experimental area. A total of ≈6500 and ≈3000 spittlebugs were released during Apulia and Piedmont experiments, respectively. Spittlebugs were recaptured with sweep net (10–250 m distance from release point) every two or three days up to 17 days after the release. Marked insects were identified via an indirect ELISA. The dispersal capacity of P. spumarius adults was described by estimating the dispersal kernel, i.e. the probability density function describing the distribution of the recapture locations of insects relative to the release point. Spittlebugs were recaptured up to 155 meters and 200 m in Apulia and Piedmont, with 50% of total recaptures within 30 m and 40 m from the release points, respectively. Results showed a high variability in the estimated median distance from the release point, ranging from 26 m (Apulia) to 35 m (Piedmont) per day, and from 374 m (Apulia) to 507 m (Piedmont) for adult life-long dispersion. Estimated spread parameters of P. spumarius are fundamental to model X. fastidiosa spread in Apulia and other European foci. Further research is needed to investigate the influence of insect physiological status and environmental factors on movement and directionality of P. spumarius.