Host plant preferences of Hyalesthes obsoletus, the vector of the grapevine yellows disease ‘bois noir’, in Switzerland

Abstract

Bois noir is an important grapevine yellows disease in Europe that can cause serious economic losses in grapevine production. It is caused by stolbur phytoplasma strains of the taxonomic group 16Sr‐XII‐A. Hyalesthes obsoletus Signoret (Hemiptera: Cixiidae) is the most important vector of bois noir in Europe. This polyphagous planthopper is assumed to mainly use stinging nettle [Urtica dioica L. (Urticaceae)] and field bindweed [Convolvulus arvensis L. (Convolvulaceae)] as its host plants. For a better understanding of the epidemiology of bois noir in Switzerland, host plant preferences of H. obsoletus were studied in the field and in the laboratory. In vineyards of Western Switzerland, adults of H. obsoletus were primarily captured on U. dioica, but a few specimens were also caught on C. arvensis, hedge bindweed [Calystegia sepium (L.) R. Brown (Convolvulaceae)], and five other dicotyledons [i.e., Clematis vitalba L. (Ranunculaceae), Lepidium draba L. (Brassicaceae), Plantago lanceolata L. (Plantaginaceae), Polygonum aviculare L. (Polygonaceae), and Taraxacum officinale Weber (Asteraceae)]. The preference of the vector for U. dioica compared to C. arvensis was confirmed by a second, more targeted field study and by the positioning of emergence traps above the two plant species. Two‐choice experiments in the laboratory showed that H. obsoletus adults originating from U. dioica preferred to feed and to oviposit on U. dioica compared to C. arvensis. However, H. obsoletus nymphs showed no host plant preference, even though they developed much better on U. dioica than on C. arvensis. Similarly, adults survived significantly longer on U. dioica than on C. arvensis or any other plant species tested [i.e., L. draba and Lavandula angustifolia Mill. (Lamiaceae)]. In conclusion, although nymphs of H. obsoletus had no inherent host plant preference, adults tested preferred to feed and oviposit on U. dioica, which is in agreement with the observed superior performance of both nymphal and adult stages on this plant species. Urtica dioica appears to be the principal host plant of H. obsoletus in Switzerland and plays therefore an important role in the epidemiology of the bois noir disease in Swiss vineyards.

Survival relative to new and ancestral host plants, phytoplasma infection, and genetic constitution in host races of a polyphagous insect disease vector

“…In contrast to the nettle population studied by Kessler et al. (2011), the situation in Germany is such that field bindweed was the common host of H. obsoletus prior to the recent inclusion of stinging nettle. Thus, the two nettle-associations differ in their historical, genetic and resource backgrounds but produced similar adaptive implications for the trait survival.…”

In-vineyard population structure of ‘Candidatus Phytoplasma solani’ using multilocus sequence typing analysis

“…genetic diversity of 'Ca. P. solani' has been reported and generally related to complex interactions between the vector and the wide range of wild host plants (Kessler et al, 2011;Riolo et al, 2012). The phylogenetic analyses that were carried out for the vmp1, stamp, and secY genes were useful to study the relationships that the 'Ca.…”

“…In recent years, rapid spreading of BN has been seen frequently, and this can be a limiting factor in several grapevine-growing regions (Maixner, 2011;Zahavi et al, 2013). BN spreading is influenced by the biology of the main vector, Hyalesthes obsoletus, together with other potential vectors (Imo et al, 2013;Landi et al, 2013;Cvrković et al, 2014), and their wide range of host plants (Kessler et al, 2011;Johannesen et al, 2012;Riolo et al, 2012;Cvrković et al, 2014). Disease management for BN is very difficult, as the phytoplasma and insect vectors are both not host specific, and thus their control is mainly based on agronomic approaches.…”

Correlation of bois noir disease with nettle and vector abundance in northern Italy vineyards

“…For the BN nettle-type, the cultural control practices against U. dioica could be useful to reduce the disease (Maixner 2007;Kessler et al 2011) as showed by decreases of H. obsoletus population levels (Stark-Urnau and Kast 2008;Maixner et al 2010). In particular, the presence of U. dioica mostly in herbaceous vegetation surrounding the vineyard area and the edge effect in the spatial distribution of affected grapevines suggests controlling nettle in the ditches.…”