Title "Control strategies of Drosophila suzukii in South Tyrol"

Drosophila suzukii, also known as Spotted Wing Drosophila, has become a pest in Europe since last 2 years. Also in the Italian region Trentino-South Tyrol D. suzukii damaged a large amount of soft fruits like cherries, strawberries, blueberries, etc. In vineyards D. suzukii showed high damage in red wine cultivars, particularly in Schiava Grigia grapevine, the most cultivated variety in South Tyrol. The damage of D. suzukii is caused by the females. They lay eggs inside the fruits and than the hatched larva are feeding inside the fruits and consequently the fruits become uneatable and also very vulnerable to pathogens. Preliminary studies showed that the ovideposition time is close to the harvesting of wine grapes, therefore it is impossible to perform insecticide threats before harvesting considering the residual pesticides. The first aim of this thesis is to monitor the population dynamic of D. suzukii in South Tyrol, taking into account different vineyards fields in the surrounding the municipality of Salorno, where several wine cultivars are planted. In particular we will monitor D. suzukii population from April to October 2012 in 8 different vineyards. In each vineyard one of the following cultivars has been planted: Pinot Grigio, Pinot Bianco, Chardonnay, Gewürztraminer for the white wine varieties and Merlot, Pinot Nero, Lagarin and Schiava Grigia for the red wine varieties. These are the 8 most important South Tyrolean wine cultivars, in terms of planted hectares. Real damage of D. suzukii at harvesting time will be also estimated for all investigated fileds . A second aim of this thesis is to analyse when D. suzukii start to lay eggs starting from a certain ripening stadium of the grape. Every week, a certain number of grapes will be harvested and exposed to a laboratory infestation of D. suzukii. Eggs to each berry will be counted and an attractiveness index for the 8 varieties at different ripening stages will be calculated. These results will be compared with the monitoring and the damage data. The last aim of this thesis is to study if larvae D. suzukii have any preference of grape juice collected from the 8 investigated varieties.