Philaenus spumarius is a vector of Xylella fastidiosa, one of the most dangerous plants pathogenic
bacteria worldwide. There is currently no control measure against this pathogen. Thus, the
development of vector control strategies, like generalist predators, such as spiders, could be
essential to limit the spread of this vector-borne pathogen. In this study, a polymerase chain reaction
(PCR)-based approach was developed to principally detect DNA of P. spumarius in the spider’s gut.
Accordingly, 20 primer pairs, targeting the mitochondrial cytochrome oxidase I (COI) and cytochrome
b (cytB) genes, were tested for specificity, sensitivity, and efficiency in detecting P. spumarius DNA.
Overall, two primer sets, targeting COI gene (COI_Ph71F/COI_Ph941R) and the cytB gene (cytB_
Ph85F/cytB_Ph635R), showed the highest specificity and sensitivity, being able to amplify 870 pb and
550 bp fragments, respectively, with P. spumarius DNA concentrations 100-fold lower than that of the
DNA of non-target species. Among these two primer sets, the cytB_Ph85F/cytB_Ph635R was able to
detect P. spumarius in the spider Xysticus acerbus, reaching 50% detection success 82 h after feeding.
The feasibility of this primer set to detect predation of P. spumarius by spiders was confirmed in the
field, where 20% of the collected spiders presented positive amplifications.
This work was supported by the EU H2020 Research Project XF-ACTORS “Xylella fastidiosa Active Containment
Through a multidisciplinary-Oriented Research Strategy” (Grant Agreement 727987) and to the Foundation
for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO
(UIDB/00690/2020). Isabel Rodrigues also acknowledges the PhD research Grant (2020.07051.BD) provided
by FCT.
