Phenology population dynamics and host plants of Philaenus spumarius in Italian olive groves

Philaenus spumarius is the vector of the CoDiRO strain (subsp. pauca) of X. fastidiosa in the Apulian olive orchards. Detailed knowledge on ecology and phenology of P. spumarius is needed to design control measures aiming at slowing disease progression and assessing the risk in noninfected areas. Open field surveys are conducted in olive orchards in Liguria and Apulia Regions of Italy. Structured population dynamics, host-plant association, seasonal movement between crop and wild species, were investigated by field surveys from March 2016 and are scheduled until the end of 2017. Nymph population in the grass cover was estimated by direct counting in thirty random sampling units (SU) in each olive orchard. Life stage of the insect, host-plant and its phenological stage were recorded. Adults were collected with sweeping net on three different vegetational components: grass cover (30 SU), olive canopy (20 SU), and alternative woody hosts (10 SU). All samplings were conservative to avoid disturbance to spittlebug population. Nymph population peaked in the second half of April in Liguria and at the end of March in Apulia. Early instars were frequently found on plants with basal rosettes, mainly Asteraceae, while later instars moved to upper part of the plant, exploiting many more plant species. Adults show host-shifting during the season as they move from herbaceous hosts to woody plants in the summer and come back to grass cover at the end of the summer