Soft soap and linalool as potential management tools for Philaenus spumarius (Hemiptera: Aphrophoridae), vector of Xylella fastidiosa

Abstract

Philaenus spumarius (Hemiptera: Aphrophoridae) is one of the most polyphagous xylem-feeding pests. It recently acquired bad fame when it was identified as the main vector of the bacterium Xylella fastidiosa, the causal agent of the Olive Quick Decline Syndrome that, within ten years, has affected and led to the death of more than 21 million olive trees in the Southern Italian region Apulia alone. Despite the agricultural practices and synthetic insecticides available, as not sufficiently effective, more strategies to target all the developmental instars of the pest and eco-friendly formulations, especially in organic orchards, are urgently needed. Therefore, the main goals of this work were to test the toxicity of a solution of potassium salts of fatty acids (soft soap) on P. spumarius juveniles and assess the attractiveness exerted by linalool on adults in a planar olfactometer. According to our results, the average neanids/nymphs’ mortality was 82.2 ± 10.4% 24h after spraying the soft soap on them at the labelled dose. Regarding the adults, linalool was significantly attractive to both sexes in a concentrations range between 0.01 and 0.12 μL linalool L⁻¹ air. Our purpose is to potentially suggest a dual, integrated control approach against P. spumarius, with the soft soap as a biopesticide to reduce the immature stages of the pest and attractive, linalool-activated traps to numerically cull the population of the meadow spittlebug as part of a broader management system.