Female Ganaspis brasiliensis (Photo T. Haye)

Following surveys in China and Japan, DROPSA partners are now evaluating the suitability of Asian parasitoids for the biological control of D. suzukii in Europe. The most promising candidate is a small wasp of the family Figitidae, provisionally identified as Ganaspis brasiliensis (but the taxonomy of the Ganaspis genus is under revision). This wasp is the most promising candidate for introduction into Europe, firstly because it is by far the most frequent and abundant parasitoid of D. suzukii in China and Japan, and secondly because it is the one that shows the highest specificity for D. suzukii. However, more work is required before a dossier for the introduction of the parasitoid can be submitted. In the near future, the partners will complete the specificity assessment, assess the climatic compatibility with infested areas in Europe, test the existence of sibling species or ecotypes varying in their specificity and climatic suitability, and study the mechanisms inducing specificity.

Considering the fact that D. suzukii develops many generations per year and attacks a wide range of fruits of wild and ornamental plants, it becomes evident that long term control solutions will have to involve area-wide control methods. Biological control through the introduction of Asian natural enemies is a promising strategy for D. suzukii because, in contrast to other methods, it has the potential to lower the population levels in all habitats, limiting the possibility for D. suzukii to reinvade crops generation after generation.

Marc Kenis
CABI (Switzerland/United Kingdom)