In 2011, the spotted-wing drosophila Drosophila suzukii native to Asia has been identified
for the first time in Switzerland. Since then, this vinegar fly has established itself all over the country
and it has also been observed in many vineyards. It has been reported that D. suzukii is able with its
long, sharp, serrated ovipositor to attack healthy grapes just before harvest and that the level of
infestation depends on the grape cultivar. It is assumed that in particular red and thin-skinned cultivars
are of higher susceptibility. Our laboratory studies confirmed that D. suzukii was able to lay eggs
within grape berries. However, almost none of the eggs laid at the beginning of grape ripening allowed
the development of adults. In subsequent tests, oviposition was highest on the red and thin-skinned
cultivars Bondoletta and Gamay followed by the red cultivars Pinot Noir and Divico, and the two
white cultivars Müller-Thurgau and Chasselas. Yet, the development of adults remained very low and
did not exceed 9% of eggs deposited, which is considerably less than on an artificial diet. These
results, as well as field observations, confirm the lesser attractiveness of white compared to red grape
cultivars and the importance of the thickness of the skin. Moreover, observations in the field and
preliminary laboratory experiments indicate that grape infestation by D. suzukii does neither
considerably favor the development of other Drosophilidae nor rot diseases within grapes. Overall, our
various observations confirm that grapes can be damaged by D. suzukii, but they are probably not very
suitable for larval development and the buildup of large pest populations. Nonetheless, it cannot
definitely be excluded that D. suzukii favors the infestation of grapes by native vinegar flies and
pathogens and its development in vineyards should therefore be followed carefully.