Spittlebugs are the vectors of the bacterium Xylella fastidiosa Wells in Europe, the causal agent of olive dieback epidemic in Apulia, Italy. Selection and distribution of different spittlebug species on host-plants were investigated during field surveys in 2016–2018 in four olive orchards of Apulia and Liguria Regions of Italy. The nymphal population in the herbaceous cover was estimated using quadrat samplings. Adults were collected by sweeping net on three different vegetational components: herbaceous cover, olive canopy, and wild woody plants. Three species of spittlebugs were collected: Philaenus spumarius L., Neophilaenus campestris (Fallén), and Aphrophora alni (L.) (Hemiptera: Aphrophoridae). Philaenus spumarius was the predominant species both in Apulia and Liguria olive groves. Nymphal stages are highly polyphagous, selecting preferentially Asteraceae Fabaceae plant families, in particular some genera, e.g., Picris, Crepis, Sonchus, Bellis, Cichorium, and Medicago. Host-plant preference of nymphs varies according to the Region and through time and nymphal instar. In the monitored sites, adults peak on olive trees earlier in Apulia (i.e., during inflorescence emergence) than in Liguria (i.e., during flowering and beginning of fruit development). Principal alternative woody hosts are Quercus spp. and Pistacia spp. Knowledge concerning plant selection and ecological traits of spittlebugs in different Mediterranean olive production areas is needed to design effective and precise control strategies against X. fastidiosa vectors in olive groves, such as ground cover modifications to reduce populations of spittlebug vectors.

Spittlebugs (Hemiptera: Aphrophoridae) are the dominant xylem-sap feeders in the Mediterranean area and the only proven vectors of Xylella fastidiosa ST53, the causal agent of the olive dieback epidemic in Apulia, Italy. We have investigated the structured population phenology, abundance and seasonal movement between crops and wild plant species of both the nymphal and adult stages of different spittlebug species in olive groves. Field surveys were conducted during the 2016–2018 period in four olive orchards located in coastal and inland areas in the Apulia and Liguria regions in Italy. The nymphal population in the herbaceous cover was estimated using quadrat samplings. Adults were collected through sweep nets on three different vegetational components: herbaceous cover, olive canopy and wild woody plants. Philaenus spumarius was the most abundant species; its nymphs were collected from early March and reached a peak around mid-April, when the 4th instar was prevalent. Spittlebug adults were collected from late April until late autumn. P. spumarius adults were abundant on the herbaceous cover and olive trees in late spring, and they then dispersed to wild woody hosts during the summer and returned to the olive groves in autumn when searching for oviposition sites in the herbaceous cover. A relatively high abundance of P. spumarius was observed on olive trees during summer in the Liguria Region. The present work provides a large amount of data on the life cycle of spittlebugs within an olive agroecosystem that can be used to design effective control programmes against these vectors in infected areas and to assess the risk of the establishment and spread of X. fastidiosa to Xylella-free areas.

The scope of this project was the collection of data and information on biology, phenology and control of vectors and potential vectors of Xylella fastidiosa (referred to, from now on, as Xf vectors). Systematic literature searches covering the different topics were conducted on authoritative databases indexing peer‐reviewed scientific publications as well as on grey literature repositories. An extraction table on the ecology and phenology of Xf vectors was generated, together with a draft protocol for field data collection targeted to Philaenus spumarius. Efficacy tables on different control methods were also produced and crosschecked with data on plant protection products currently applied in the EU with effect on Xf vectors, producing a good agricultural practices table. With the help of questionnaires, we inventoried: i) the ongoing integrated pest management programmes on stone fruits, citrus, grapevine and olive crops in the Mediterranean Member States (MedMSs), and the monitoring activity on Xylella vectors currently conducted in all the EU MSs. Finally, we collected new experimental data on phenology and ecology of P. spumarius and other spittlebug species for three consecutive years (2016‐2018). The data have been collected via field surveys in olive orchards, vineyards and insect rearing at the macrocosm (field), mesocosm (screenhouse) and microcosm (small rearing cage) level. All observations in olive groves were conducted in parallel in the Apulia and Liguria regions, while those in vineyard were carried out in the Piedmont region (Italy). The results are provided in the body of the report as metanalysis and in Excel tables as supporting material and concern i) phenology, host‐plant associations and population dynamics of nymphs and adults of P. spumarius and other spittlebugs under different environmental conditions, ii) fecundity and reproductive biology from microcosms and field‐collected females. Field and mesocosm data are supported by agronomic and meteorological data.

1. Biological invasions of exotic species pose a major threat to native biodiversity. Invaders are known to have direct impacts on native species; however, less well studied are the indirect impacts mediated through the integration of invaders into trophically linked communities.2. A survey of the chalcid wasp parasitoid community attacking the chestnut gallwasp Dryocosmus kuriphilus was carried out over a 5-year period at 26 sites in northwestern Italy. More than 415 000 galls were collected and more than 10 000 parasitoid specimens emerged. Twenty-seven parasitoid species belonging to six families (Eurytomidae, Pteromalidae, Torymidae, Eupelmidae, Ormyridae, Eulophidae) were identified using morphological and molecular methods; seventeen are new records for the parasitoid community associated with D. kuriphilus in Italy. The morphospecies complexes Megastigmus dorsalis, Eupelmus urozonus, E. annulatus, and Eurytoma pistaciae were the dominant species; another six morphospecies were encountered regularly but at low frequency; and 13 species were recorded only occasionally. The attack rate of any individual parasitoid species was low, although the more common species appeared to be increasing their use of this novel host.3. Biases observed in the sex ratios of parasitoids emerging from D. kuriphilus galls suggest that parasitoid individuals are making life-history decisions to take advantage of the high abundance of this host. Overall, these patterns imply that there is an ongoing transfer of parasitoids between oak and chestnut galls, and hence a high potential for this invading species to have a major impact on native oak gall communities via indirect competition mediated through shared parasitoids.