Observations on population dynamics of leafhoppers in Western Sicily vineyards

From 2007 to 2009 field observations were carried out in two vineyards (organically and conventionally managed) in Menfi (Agrigento province, Sicily). Population dynamics of two leafhoppers, Jacobiasca lybica (cotton leafhopper) and Zygina rhamni were followed by chromotropic traps and leaf observation in field. Both species were constantly present in vineyards. Z. rhamni did not register statistical differences between the two fields, while J. lybica was mostly present in the conventionally managed field. In this last vineyard for two consecutive years (2007 and 2008) J. lybica population exceeded the intervention threshold of 0.5 leafhopper/leaf. On the other hand, in the organically managed vineyard the cotton leafhopper population remained below the intervention threshold for all the observation period