New association between Dryocosmus kuriphilus and Torymus flavipes in chestnut trees in the Bologna area (Italy): first results

Investigations into the new association between the recently introduced insect pest Dryocosmus kuriphilus Yasumatsu (Hymenoptera Cynipidae), the Asian chestnut gall wasp (ACGW), and the native parasitoid Torymus flavipes (Walker) (Hymenoptera Torymidae) were carried out in the Bologna district (Italy). The parasitoid attacks several species of gall-maker host larvae living on plants and trees, particularly oaks. In 2009, T. flavipes was already found to be parasitising the new host ACGW on chestnut trees. During 2010 and 2011 the T. flavipes parasitisation percentages, its behaviour on host larvae, its emergence trend, and its sex ratio on the non-native ACGW host were analysed.