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Flavescence dorée (FD) is a grapevine disease caused by associated phytoplasmas (FDp), which are epidemically spread by their main vector Scaphoideus titanus. The possible roles of alternative and secondary FDp plant hosts and vectors have gained interest to better understand the FDp ecology and epidemiology. A survey conducted in the surroundings of a vineyard in the Swiss Southern Alps aimed at studying the possible epidemiological role of the FDp secondary vector Orientus ishidae and the FDp host plant Alnus glutinosa is reported. Data used for the publication. Insects were captured by using a sweeping net (on common alder trees) and yellow sticky traps (Rebell Giallo, Andermatt Biocontrol AG, Switzerland) placed in the vineyard canopy. Insects were later determined and selected for molecular analyses. Grapevines and common alder samples were collected using the standard techniques. The molecular analyses were conducted in order to identify samples infected by the Flavescence dorée phytoplasma (16SrV-p) and the Bois Noir phytoplasma (16SrXII-p). A selection of the infected sampled were further characterized by map genotype and sequenced in order to compare the genotypes in insects, grapevines and common alder trees.

En raison du réchauffement climatique planétaire et de celui particulièrement marqué en Suisse, le déve-loppement de certains insectes sera fortement accé-léré (Bloesch et De Siebenthal 1988). La viticulture helvétique pourrait souffrir d'un impact plus pronon-cé des insectes ravageurs (OcCC 2007). Parmi ces in-sectes, la cicadelle Scaphoideus titanus Ball(Hemip-tera: Cicadellidae) a reçu une attention particulière au cours des quinze dernières années, puisqu'elle est le vecteur principal de la flavescence dorée (Schvester et al. 1961), une grave maladie de la vigne causée par le phytoplasme Candidatus phytoplasma vitis (IRPCM 2004). La maladie fait l'objet de mesures officielles visant à endiguer sa propagation, du fait de son carac-tère épidémique et d'un impact économique négatif élevé. Pour ces raisons, elle est inscrite comme orga-nisme de quarantaine et soumise à une lutte obliga-toire (OPV 2010).

The Nearctic leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae) was accidentally introduced in Europe, where it became the vector of the ‘Candidatus Phytoplasma vitis' phytoplasma causing the ‘Flavescence dorée' disease of grapevine plants. A time-varying distributed delay model, simulating the successive occurrences of egg hatching, nymph presence, and adult emergence, is extended here to represent multi-generation infestation patterns of grapevine plants inhabited by eggs, nymphs, and adults. The model extension includes intrinsic mortality, mortality caused by plant dormancy, and low temperatures, development of diapausing and post-diapausing eggs, fecundity rates, and adult longevity. Field observations and published data were used to estimate parameters. The model was validated with five years canopy infestation data from five vineyards not subjected to insecticide treatments and found to have satisfactory explicative and predictive qualities. The model output is most sensitive to a 10% variation in the upper threshold and in the shape parameters of the survivorship function and least sensitive to a 10% variation in the shape parameters of the development function and the survivorship level. Recommendations are made to take into account other factors than temperature and plant phenology and include a wider geographical area in further model development

Flavescence dorée and the mandatory control of its vector Scaphoideus titanus pose important problems in organic vineyards. The goal of our field studies conducted in the Ticino was to develop a pest control strategy conform to the guidelines of organic production. Insecticides containing pyrethrin were the only organic products showing an efficacy higher than 90% against the immature stages of S. titanus. However, these products had no effect on adult leafhoppers. Repeated applications of pyrethrin proved to be toxic against the predatory mite species Amblyseius andersoni. Despite this toxicity, the only efficient and recommended control strategy in organic vineyards is their application. Pyrethrin should be applied three times at an interval of ten days after the first appearance of individuals of the 3rd nymphal stage. Symptomatic plants must be eradicated from the vineyard to remove the phytoplasma inoculum.