First observations concerning Phyllocnistis vitegenella, the American grape leafminer, a new pest in Southern Switzerland.
The American grape leafminer Phyllocnistis vitegenella Clemens (Lepidoptera: Gracillariidae) is a pest with origin in North America. In Italy its occurrence was reported in 1995. In Southern Switzerland, where the insect completes three generations annually, it has been observed for the first time in 2009. Currently the region around Lugano represents its northern limit of spread. The percentage of damaged leaves per plant increases during August and September. A level of leaf damage of 30.5% was determined during the grape picking period. Evaluations carried out during the second and at the end of the third generation revealed frequencies of parasitism of 13 and 16.7% respectively were observed. This indicates a quick response of the environment to this new exotic pest. Seven species of microhymenoptera were determined, belonging to Eulophidae family. The observed parasitism is mainly attributed to three species: Chrysocharis nephereus, Minotetrastichus ecus and Ciosterocerus trifasciatus.