Role of winter host plants in the phenology and vineyard colonization pattern of Zygina rhamni (Hemiptera: Cicadellidae: Typhlocybinae)

ABSTRACT Zygina rhamni Ferrari (Hemiptera: Cicadellidae: Typhlocybinae) is a mesophyll-feeding\n\nleafhopper that infests grapevine, Vitis vinifera L. This leafhopperÕs overwintering strategy and the\n\ndynamics of its vineyard colonization, relative to the distance between the grapevines and the winter\n\nhost plants and different grapevine vegetative densities, are described herein. This species shows a\n\nfacultative heteroecious life cycle. In autumn, it migrates from vineyards to bramble, Rubus gr.\n\nfruticosus, and rose, Rosa chinensis Jacquin. On these host plants, females lay eggs that start to hatch\n\nat the end of March. Adults that developed on bramble colonize grapevines beginning in May; the leaf\n\nfall of rose, which takes place during the Þrst half of April, probably causes the death of unhatched\n\neggs and nymphs.Wefound that overwintering females can move back to vineyards and lay eggs until\n\nearly June. The dynamics of vineyard colonization by the leafhopper involved initial concentration\n\nin areas close to bramble (MayÐearly July) with subsequent, progressive spread through the vineyards,\n\nwith concentration in areas of high vegetative density. Leafhopper presence was negligible in areas\n\nof vineyards with levels of vegetative density below a certain threshold.