Identifying the drivers of abundance of Philaenus spumarius in Corsica

Philaenus spumarius (Hemiptera: Aphrophoridae) is a major vector of Xylella fastidiosa (Xf) in Europe. However, the drivers influencing its abundance are still poorly known. In Corsica from 2018 to 2020, we monitored the abundance of P. spumarius three times a year in 64 permanent plots distributed along vegetation and altitudinal (0-600m) gradients. The vegetation gradient ranged from shrubland to oak forest and accounted for the density of Cistus monspeliensis on which P. spumarius usually develops and feed in Corsica. Abundance of P. spumarius was estimated through visual counting of foams and sweep netting of adults. Both vegetation composition and climate descriptors were recorded at each sampling location. We used partial least squares path modelling and generalized linear mixed models to unravel the relationships between vegetation / climate descriptors and P. spumarius abundance.

Philaenus spumarius abundance significantly decreases with increasing average temperature. Abundance of P. spumarius was significantly and positively correlated with C. monspeliensis density, confirming difference in host plant preference between Corsica and mainland France. A significant effect of vegetation structure was also found with forests hosting lower P. spumarius abundance.

The strong association observed between P. spumarius and C. monspeliensis suggests that Xf expansion may have been facilitated by firebreaks or disturbed habitats where C. monspeliensis is abundant as an early colonizer. Managing C. monspeliensis in the vicinity of agricultural areas may constitute an essential component of prophylaxis against Xf in Corsica.