Host plant use by spittlebug nymphs in agroecosystems: a field survey supporting targeted vegetation management

Current strategies aimed at containing the spread of the vector-borne bacterium Xylella fastidiosa (Wells et al. 1987) include ground cover removal and tillage in order to curb the population of juveniles of spittlebug vectors, such as Philaenus spumarius (Linnaeus 1758) (Hemiptera: Aphrophoridae) and Neophilaenus campestris (Fallén 1805) (Hemiptera: Aphrophoridae). However, continuous tillage might harm soil, biodiversity, and ecosystem services. Here we present data on host plant use by juveniles of the 2 spittlebug species obtained through a survey carried out in 105 olive orchard plots across Apulia region, South-East Italy. P. spumarius juveniles were absent from species such as Oxalis pes-caprae (Linnaeus 1753), Astragalus hamosus (Linnaeus), Mercurialis annua (Linnaeus 1753), Fumaria parviflora (Lamarck), and Muscari spp., while N. campestris almost exclusively developed on Poaceae, avoiding most dicots. Host selection was species-specific rather than family-dependent, possibly reflecting differences in xylem chemistry and/or plant architecture. These findings provide empirical support for selective vegetation management: using plant species unsuitable for spittlebug nymphs could reduce vector populations while preserving ground cover benefits, avoiding the ecological shortcomings of indiscriminate removal. However, causal mechanisms remain untested, and the efficacy of this approach in reducing pathogen spread needs experimental validation. Moreover, potential side effects on non-target organisms and ecosystem functions require careful ecological assessment before large-scale implementation.