Behavioural response of the main vector of Xylella fastidiosa towards olive VOCs

The characterization of behavioural cues involved in the location of a host-plant by a phytophagous insect allowsthe elaboration of tools that can be exploited in the sustainable protection of cultivated plants. In this context, the identificationoftheblendofVolatileOrganicCompounds(VOCs)releasedbyahostplantcanbeprofitablyusedfordivertingpestinsectsawayfromitandtowardsspecifictargets(plants,traps).Philaenusspumarius,the mainvectorofXylellafastidiosa,i.e.,the pathogenbacteriumresponsibleforthe OliveQuickDeclineSyndrome(OQDS),moves toolivetreeswhenthegrasscover dries up. Todate, the possible role of chemical cuesregulatingthis passage is not known. Moreover,it is stilltobe testedwhether VOCsare involved in the resistancetothe bacteriumrecorded intwo olive varieties,namelyFS-17andLeccino.Toverify these hypotheses,we characterized thebehaviouralresponseof P.spumariustowards the tworesistant(Leccino,FS-17)and three commonsusceptible olivetreesvarieties (Ogliarola,FrantoioandRotondella) inolfactometerbioassays.Theresponse of P.spumariustowards olive varietieswassex-dependent: malesweretotally unresponsivewhilstfemaleswereattractedbyOgliarola,RotondellaandFrantoio,andrepelledbyFS-17.No preference wasrecorded whentestingfemalesagainstLeccinoandcleanair.ThecharacterizationandthequantificationoftheVOCsreleasedbytheolivevarietiestestedsupported the behavioural observationsand paved the way to discuss their possible role in the elaborationofintegrated protocols for the sustainable protection of olive trees from the deadly expansion of X.fastidiosa.