Seasonal flight activity and genetic relatedness of Torymus species in Italy

Abstract

Abstract Torymus sinensis Kamijo was released into Europe to control the Asian chestnut gall wasp Dryocosmus kuriphilus Yasumatsu, proving to be an effective biocontrol agent. In Japan, hybrids between this exotic parasitoid and the native congeneric Torymus beneficus Yasumatsu and Kamijo have been recorded, whereas no case of hybridization with natives has been reported for Europe. The seasonal phenology of the Torymus species was investigated in north‐west Italy and 172 997 chestnut galls (Castanea spp.), 7866 oak galls (Quercus spp.), 29 wild rose galls (Rosa spp.) and 44 bramble galls (Rubus spp.) were collected over a 5‐year period. The seasonal flight activity was recorded for eight native Torymus species [Torymus affinis (Fonscolombe), Torymus auratus (Müller), Torymus bedeguaris (L.), Torymus calcaratus Nees, Torymus cyaneus Walker, Torymus flavipes (Walker), Torymus geranii (Walker) and Torymus notatus (Walker)] and five of them were found to overlap with T. sinensis flight, namely T. affinis, T. auratus, T. flavipes, T. geranii and T. notatus. Among the Torymus native species, T. notatus revealed to be morphologically and phylogenetically closely related to T. sinensis, thus suggesting hybridization potential.