Relative efficacy of different colour sticky traps for the capture of vectors of Xylella fastidiosa

Xylella fastidiosa is one of the main quarantine pathogens of the European Union that is transmitted by xylem-feeder insects (i.e. Cicadomorpha). This bacterium affects plant species of great economic importance such as almond, olive , and vine, among others. During 2020 we conducted a trial in Mallorca (Balearic Islands; Spain) to study the efficacy of colour sticky traps to capture spittle bugs (Aphrophoridae) which are considered major vectors of X. fastidiosa in the EU. Samplings were carried out weekly, from June to December 2020 in three plots: one almond orchard, one olive orchard, and one vineyard. In each plot, 16 traps of each colour (red, yellow, blue and white) were used. Traps were placed using a Latin square design  in the tree canopy, cover vegetation and woody bordering shrubs. The sticky trap performance was also compared to the results obtained by using a sweeping net in the same plots during the same period of sampling. A total of 89 individuals were captured, 73 Philaenus spumarius and 16 Neophilaenus campestris, using 3458 sticky traps. The highest number of insects were captured in olive (59.55%), followed by vineyard (22.47%) and almond (17.98%). Depending on the location of the trap, 60.67% of insects were captured in trees, while 20.22% were in the cover vegetation and 19.10% in bordering shrubs. Vectors showed preference for yellow colour (57 captures; p<0.005) compared to red, white, or blue colour traps. Sticky traps showed lower number of insects (89 insects) compared to the sampling by using sweeping net (108 insects). Our results highlight that yellow coloured sticky traps are the most effective for capturing vectors of X. fastidiosa in the main crops of the Balearic Islands.