## 2 Main Arthropod Pests/Vectors in Olive Groves
### Fam. Aphrophoridae  
The arrival of the bacterium _Xyella fistidisa_ ([PERSON] et al. 1987) in Europe in 2013 has posed another challenge to the agricultural economies of Mediterranean countries. This bacterium grows very slowly in microbiological culture media (_fastidiosa_), and it lives in the xylem of host plants (_Xyella_), causing a disease that seriously damages crops of high economic interest such as olive trees. The first outbreak of \"Olive quick decline syndrome\" (OQDS) was reported in Apulia (Italy) in 2013. This is a disease that can be asymptomatic in its early stages, but usually causes leaf scorching, extensive dieback, and eventually the death of the entire affected plant. Since then, the Aphrophoridae species _Philianus spumarius_ ([PERSON] 1758), _Pilianeus italosignus_, and _Neophilaneus camepstris_ ([PERSON] 1805) have been catalogued as vectors of the bacterium _Xyella fistidiosa_ in the Mediterranean area [10; 39; 40; 41]. _P. spumarius_, the meadow spittlebug, is the main vector of _Xyella fistidisa_ in Europe of the above species in Europe. These xylem sap-feeding aphrophorids are ubiquitous and highly polyphagous species that can feed on a wide variety of plant species, mainly herbs and buses, but also olive trees [42]. The acquisition of _X. fistidiosa_ involves its attachment to the foregut of adults from source plants, which transmit the bacteria to other plant species during the feeding process [43; 44]. The eggs overwinter in the soil until early spring, when nymphal stages begin to develop in suitable herbs, preferably with a basal leaf rosette or with closely adjacent leaf and stem surfaces [45; 46] (Figure 2). Between spring and summer, these species have long relative adult life intervals, which end in autumn with the oviposition of the females [47].  
In general, the damage caused by vectors is often greater than that caused by insect pests. The single inoculation of the vectored pathogen continues to inflict damage throughout the plant and over time. In contrast, pest species attack an organ or structure at specific moments [47]. Due to the lethal consequences of _X. fistidiosa_ infection, the management of this bacterium is currently based on monitoring and controlling its vectors, as there are no effective tools to combat this plant pathogen. Existing management measures are focused on controlling the vectors at their different stages: eggs [48], juveniles, and adults [49].  
In addition to the enormous direct losses caused by the attack by _X. fustidiosa_, there are also the losses caused by the control measures, which include the eradication of all plants within a 100 m radius of the infested plant and heavy treatments with phytosanitary products throughout the eradication area [50]. It has been estimated that a full spread of _X. fustidiosa_ could eventually cost the EU more than EUR 5.5 billion per year in production losses, with potential export losses of EUR 0.7 billion per year. If _Xylella_ were to spread across the EU, it could affect over 70% of the production value of EU olive trees over 30 years old and could affect 35% of younger trees ([51] and references therein).