The Role of Hyalesthes obsoletus (Hemiptera: Cixiidae) in the Occurrence of Bois noir of Grapevines in France

Abstract

An epidemiological study on a grapevine yellows disease called bois noir was carried out for 3 years in the Rhone valley (France). This yellows is caused by a stolbur type phytoplasma. Vectors and alternative host plants were searched, and the inoculation period was determined. Detection of stolbur phytoplasma in insects and plants was obtained using primers STOLl 1 f2,rl. In addition, a nested polymerase chain reaction (PCR) was used with primers P1/P7 and fU5/rU3 for detection in stolburinfected plants with low titre. Several thousand insects were captured and species of Hemiptera were listed. Fourteen wild or reared Hemiptera species were used in transmission trials. Thirty-four wild species were monitored for phytoplasma DNA by PCR. A planthopper.Hvalesthes obsoletus Sign., tested positive for stolbur at a level of 28% (98,/343) in 1995(98,/343) in and 38% (205,529) in 1996(98,/343) in . In 1995 leafhoppers, Mocydia crocea (1 78) and Euscelis tineolatus (2/309), were infected at a much lower ratio. Successful experimental transmission to grapevine, periwinkle and thorn apple was only obtained with H. obsoletus. Among wild plant species, hoary cress (Cardaria draba L.), bindweed (Convolvulus arvensis L.), sweet cherry {Prunus sp,), plum (Prunus domestica L), lilac (Syringa vulgaris L.), fig tree [Ficus carica L.) and elm {Ulmus sp.) were shown to be stolbur infected and hoary cress was identified as a new host plant for H. obsoletus in France. The role of some fallow lands close to vineyards as sites where the inoculum of stolbur phytoplasma was maintained in insect vector and reservoir plants, is discussed. The natural inoculation period to grapevine was shown to extend from June to August, corresponding to the adult activity of H. obsoletus. Together with the close relationships of the phytoplasmas involved in vergilbungskrankheit, a German grapevine disease, and bois noir. The results of this study suggest that the two yellows are very close. Zusammenfassung Bedeutung von Hyalesthes obsoletus (Hemiptera: Cixiidae) fur das Auftreten der Bois-noir-Krankheit der Weinrebe in Frankreich Im franzosischen Rhonetal wurde eine 3-jahrige epidemiologische Studie iiber die Bois-noir-Vergilbungskrankheit der Weinrebe durchgefuhrt. Diese Krankheit wird von einem Phytoplasma des Stolbur-Typs ausgelost. Es wurde nach Vektoren und alternativen Wirtspflanzen gesucht, und die Inokulationsperiode wurde bestimmt. Die Detektion von Stolbur-Phytoplasmen in insekten und Pftanzen erfolgte mit Hilfe der Primer STOL 1! f2/rl. Zudem wurde eine genestete PCR mit den Primem P1 /P7 und fU5 rU3 zur Detektion in stolburinfizierten Pflanzen mit niedrigem Titer durchgefuhrt. Mehrere tausend Insekten wurden gefangen, und die Hemiptera-Arten wurden aufgelistet. 14 wilde oder geziichtete HemipteraArten wurden in Ubertragungsversuchen verwendet, und 34 Wildarten wurden mittels PCR auf Phytoplasma-DNA untersucht. Der Fulgoride Hvalesthes obsoletus Sign, war 1995 mit 28% (98/343) und 1996 nut 38% (205/529) der getesteten Tiere stolburpositiv. ...

Soil erosion and earthworm population responses to soil management systems in steep-slope vineyards ..

“…In our trial, some weeds, which are known as host plants for grapevine phytoplasm carriers (e.g. Bois noir) Sforza et al (1998), did not occur at all, although the soil tillage applied in our investigation could promote their growth and multiplication.…”

Insect Vector Transmission Assays

“…ants) and to the watering of potted plants to avoid drowning of nymphs. The rearing technique has been described for the planthopper Hyalesthes obsoletus (11). Some psyllids (e.g.…”

The biology of Canadian weeds. 3. Lepidium draba L., L. chalepense L., L. appelianum Al-Shehbaz (updated)

“…In Germany, a newly identified disease causing virescence (excessive greening of floral tissue), yellowing, and phyllody (leaf-like petals and sepals) of L. draba was found to be associated with a strain of the aster yellows (AY) phytoplasma (Schneider et al 1997). In a study in France on the stolbur phytoplasma Grapevine Yellows (GY) disease known as ''bois noir'', L. draba was shown to be infected, and a probable vector of the disease (Sforza et al 1998). …”

“…In former Yugoslavia, L. draba was host to 82 insect species from 33 families and 9 genera, of which 73% were polyphagous or oligophagous species (Tosic et al 1996). In France, L. draba was among hosts of the planthopper Hyalesthes obsoletus Signoret (Hemiptera: Cixiidae), an important phytoplasma vector in Europe, which overwinters as larvae on the roots (Sforza et al 1998(Sforza et al , 1999. The mite Aceria drabae Nal.…”