PCR identification of parasitic hymenoptera as antagonists of Drosophila suzukii: sensitivity and detection limits.
The Spotted Wing Drosophila Drosophila suzukii is the worst invasive pest species on fruit cultures, including stone fruits, soft fruits and grapes in Germany and it is difficult to control. Parasitic hymenoptera seem to be less specific towards single species of the genus Drosophila and larval parasitoids cannot develop completely on D. suzukii in Germany. So far only the pupal parasitoids Pachycrepoideus vindemiae and Trichopria drosophilae are successful parasitoids on D. suzukii. On the other hand there might be specific relations that have not been detected yet on species level or even intraspecific. This preliminary study aims to build up reference data for fast and safe identifying of parasitic hymenoptera collected either directly from pupae, by baiting, with malaise traps or as bycatches of Drosophila suzukii monitoring traps. Molecular analysis of the ITS-2 region can easily separate the most abundant parasitic hymenoptera species that parasitize Drosophila species. Not only total insects but also parts, like single legs can be used for PCR-identification. Also parasitized pupae of Drosophila suzukii, empty pupae and exuviae from hatched parasitoids from empty pupae can be analysed. Identification of the parasitoid species was even possible with empty pupae that have been stored for more than 100 days. Since it is already established in other research areas molecular identification should be used more often in plant protection programmes to enhance the necessary reference building process.