Life cycle and phenology of the green leafhopper, Cicadella viridis (L.) (Homoptera: Cicadellidae), in two different climatic areas of northeastern Italy

Abstract

During 1987-1998 research was carried out on the life cycle and phenology of the green leafhopper, Cicadella viridis (L.) (Homoptera: Cicadellidae), in a mountain and in two flatland localities of northeastem Italy. Field samplings of nymphs and adults were made using sweet-net and yellow-sticky traps. In flatland localities nymphs were observed from mid April to mid October and adults from mid-late May to mid-late November. Three peaks were observed both for nymphs and for adults. In the mountain locality nymphs were observed from early May to mid October and adults from early June to late October. Two peaks occurred both for nymphs and for adults. The data collected on adult and nymph dynamics, adult sex-ratio and females with eggs in ovaries show that C. viridis in northeastern Italy has three generations a year in flatland localities and two in the mountain locality. The day-degrees were calculated for the most important phenological steps. Results of this research were compared with those reported in the literature and are discussed in relation to the fact that the leafhopper could be a vector of the bacterium Xylella fastidiosa Wells et al., the causal agent of Pierce's disease of grapevine.