Scaphoideus titanus and Metcalfa pruinosa egg distributionon different woody parts of Kober 5BB grapevine
Abstract: Egg distribution of Scaphoideus titanus Ball, the vector of the grapevine diseaseFlavescence dorée, and of Metcalfa pruinosa (Say), one of the most common planthopper in theItalian vineyards, was investigated on Kober 5BB grapevines to verify the ovipositionpreferential sites in terms of the age and the anatomic part of the cane.Wood samples of one, two-three and more than three year old vines from an abandonedfield in Veneto (Northern Italy) were analysed. The vine samples were collected during winter,stocked at 4°C till the beginning of June, cut in pieces of different length and then put in rearingboxes, maintained at 24°C, 75% RH and 16:8 photoperiod, to obtain the first instar larvae ofS. titanus and M. pruinosa. At the end of egg hatching, some pieces of one and two-three year oldcanes were analysed under a dissecting to evaluate the different susceptibility of buds, nodes andinternodes to host the eggs of the two Auchenorrhyncha. The same observations were conductedon portions of elder wood (Sambucus nigra L.) to verify the presence of eggs of the two insects.Both species, in particular S. titanus, showed a strong preference to lay eggs in the bark oftwo or older canes, even if the one year old wood was confirmed to be susceptible to egg laying.In both species the node area, in particular the zone close to the bud was preferred to theinternodes’ area, mainly with regard to the one year old wood. Our results confirm the hypothesisthat the different parts of the branch of the vine show differences in terms of susceptibility tooviposition by the two species.