Weed diversity in olive groves – shelter for insect vectors of Xylella fastidiosa

Abstract: In the course of the project FCT856 – XF-Freeolive (2015-2019), the weed cover was characterized in three olive groves. The weeds with Cercopoidea spittlebugs foam were analysed and the presence of adults in the undercanopy cover was registered. In the laboratory, the spittlebug nymphs present inside the foam were extracted. Weeds were identified through morphological characteristics and the nymphs by biomolecular methods. At the same time, adult insect vectors of Xylella fastidiosa were also captured in three olive groves, in the north (Mirandela region), centre (Abrantes region) and south of Portugal (Serpa region), by using sweep net applied to the weeds. They were identified by their morphological characteristics. All the samples collected were screened for Xylella fastidiosa, by qPCR. The botanic families where the presence of spittlebug foam was most frequent were: Asteraceae (11 species), Poaceae (11 species), Fabaceae (6 species), Brassicaceae (5 species) and Geraniaceae (4 species). Philaenus spumarius and Neophilaenus campestris adults were detected. The biomolecular identification of nymphs using molecular markers showed that they were Philaenus sp. All the samples (plants, nymphs and adults) tested negative for Xylella fastidiosa in the regions under study.