Invasive host for invasive pest: when the Asiatic cherry fly (Drosophila suzukii) meets the American black cherry (Prunus serotina) in Europe

The vinegar fly Drosophila suzukii Matsumara (Diptera: Drosophilidae), native to Asia, recently invaded Europe and North America. By contrast to other frugivorous Drosophila species, D. suzukii lays eggs on ripening fruits, heavily reducing fruit production. Although cultivated host plants of D. suzukii are well documented, very little is known about wild hosts in the invaded areas. 2 The American black cherry Prunus serotina Ehrh., a tree species native to North America, became one of the main woody forest invaders in Europe. One cause of its invasion success is the huge amount of fruit produced by P. serotina trees. 3 A field survey showed that P. serotina is a suitable reservoir for the development and persistence of D. suzukii populations in European natural systems (on the forest area investigated, up to 70% of all the fruits of P. serotina were infested in one of the sampling sites). 4 Laboratory tests demonstrated that D. suzukii prefers ripening cherries to ripe ones, therefore increasing the chance of the larvae to fully develop and reach maturity before the mesocarp of the fruit totally decays. 5 Infestation of P. serotina cherries could reduce the life span of fruits, as well as their attractiveness to seed consumers and dispersers, yet P. serotina could represent a suitable plant reservoir promoting D. suzukii invasion in Europe and North America.