Distribution and Relative Abundance of Insect Vectors of Xylella fastidiosa in Olive Groves of the Iberian Peninsula

Abstract

The phytosanitary emergency caused by the spread of Xylella fastidiosa in the Mediterranean has raised demands for a better understanding of the ecology of its presumed and candidate insect vectors. Here, we present the results of a two-year survey carried out in olive groves across southern, eastern and Central Spain and northeastern Portugal. Several sampling methods were tested and compared to select the most appropriate to estimate population levels of potential vectors of X. fastidiosa. The spittlebugs Philaenus spumarius and Neophilaenus campestris (Hemiptera: Aphrophoridae) were the main species associated with olive groves. Both species were widely present on herbaceous ground vegetation within the olive groves; P. spumarius mainly associated with Asteraceae and N. campestris with Poaceae. Due to the patchy distribution of spittlebugs within the olive groves, sweep nets were the most effective and least time-consuming sampling method for the estimation of population size both in the ground cover and tree canopies. Trends in population density showed that spittlebugs can be abundant on ground vegetation but very rare on olive canopies. Spittlebugs disperse in late spring to non-cultivated hosts that act as natural reservoirs. In late fall, adults return to the olive groves for oviposition. However, olive trees may act as transient hosts for spittlebugs and high population densities of these insect vectors should be avoided in areas where X. fastidiosa is present.

A Guild-Based Protocol to Target Potential Natural Enemies of Philaenus spumarius (Hemiptera: Aphrophoridae), a Vector of Xylella fastidiosa (Xanthomonadaceae): A Case Study with Spiders in the Olive Grove

“…The importance of A. cucurbitina relies on the fact that both the spider species and P. spumarius inhabit the olive tree canopy [42][43][44], thus there occurs spatial overlapping of the potential natural enemy and the pest. However, spittlebugs disperse in late spring to non-cultivated patches that act as natural reservoirs [45]. In our study area, the most common surrounding patches correspond to semi-natural Mediterranean shrublands.…”

The invasive moth Paysandisia archon in Europe: Biology and control options

“…The climate is characterized by hot, dry summers and cool winters, which together with the diversity of environmental conditions present in Mediterranean ecosystems (e.g., agroforest systems, fruit orchards, mixed forest stands and the urban interface), provides many options for the invasion of non‐native species. Some notable examples include outbreaks of Xylella fastidiosa Wells et al (causal agent of a quick decline syndrome in Olea europaea L., among a wide range of plant hosts) vectorized by some xylem‐sap feeder insects (Hemiptera: Aphrophoridae, Cercopidae, Clastopteridae and Cicadellinae; Janse & Obradovic, 2010; Morente et al, 2018; Sicard et al, 2018); Cryphonectria parasitica (Murrill) M.E. Barr, an ascomycete fungus that causes chestnut blight (Robin & Heiniger, 2001); the pinewood nematode ( Bursaphelenchus xylophilus [Steiner & Buhrer] Nickle), the causal agent of the devastating pine wilt disease (Vicente, Espada, Vieira, & Mota, 2012); and the Asian gall wasp ( Dryocosmus kuriphilus Yasumatsu), which strongly reduces the yield of chestnut orchards (EFSA Panel on Plant Health, 2010).…”

Tracking the outbreak. An optimized delimiting survey strategy forXylella fastidiosa

“…The species Xf develops in the vascular system of the plants and it is naturally transmitted by xylem sap-feeding insects, which spread the pathogen to relatively short distances (Almeida et al, 2014). Long-distance spread is usually associated with human activities that involve moving infected plant hosts or vectors (Nunney et al, 2014;Morente et al, 2018). Originally, the geographic distribution of the bacterium was restricted to the Americas, where it was endemic (EFSA, 2019).…”