The invasive spotted wing drosophila Drosophila suzukii, a fruit fly of Asian origin, is a major pest of a wide variety of berry and stone fruits in Europe. One of the characteristics of this fly is its wide host range. A better knowledge of its host range outside cultivated areas is essential to develop sustainable integrated pest management strategies. Field surveys were carried out during two years in Italy, the Netherlands and Switzerland. Fruits of 165 potential host plant species were collected, including mostly wild and ornamental plants. Over 24,000 D. suzukii adults emerged from 84 plant species belonging to 19 families, 38 of which being non-native. Forty-two plants were reported for the first time as hosts of D. suzukii. The highest infestations were found in fruits of the genera Cornus, Prunus, Rubus, Sambucus and Vaccinium as well as in Ficus carica, Frangula alnus, Phytolacca americana and Taxus baccata. Based on these data, management methods are suggested. Ornamental and hedge plants in the vicinity of fruit crops and orchards can be selected according to their susceptibility to D. suzukii. However, the widespread availability and abundance of non-crop hosts and the lack of efficient native parasitoids suggest the need for an area-wide control approach.

Multiple applications of hydrophobic kaolin particle film in apple orchards suppressed numbers of blossom weevil (Anthonomus pomorum), brown leaf weevil (Phyllobius oblongus), attelabid weevil (Caenorhinus pauxillus), leafhoppers (Empoasca vitis and Zygina flammigera) and green apple aphid (Aphis pomi) colonies. The kaolin treatments reduced the apple sawfly (Hoplocampa testudinea) fruit infestation on cultivar J. Grieve, and the fruit damage caused by oyster scale (Quadraspidiotus ostreaeformis), mussel scale (Lepidosaphes ulmi), early caterpillars, leaf rolling moths (Tortricidae), fruitlet‐mining tortrix moth (Pammene rhediella) and codling moth (Cydia pomonella). There was no effect on the number of colonies of rosy leaf curling aphid (Dysaphis devecta), nor on the fruit damage caused by common earwig (Forficula auricularia) and apple sawfly on cv. G. Delicious. The level of infestation of rosy apple aphid (Dysaphis plantaginea), leaf miner moths (Phyllonorycter blancardella, Lyonetia clerkella), and agromyzid flies (Phytomyza heringiana) increased in the kaolin‐treated plots. Kaolin treatments promoted woolly apple aphid (Eriosoma lanigerum) infestation, which became severe, while it reduced the abundance of polyphagous predators like F. auricularia, predaceous Heteroptera and Coleoptera, the red velvet mite (Allothrombium fuliginosum), spiders (Araneae) and the abundance of common black ant (Lasius niger). The treatments also reduced parasitism of the apple sawfly by the ichneumonid Lathrolestes ensator. Many weeks after ending the kaolin treatments, the number of predaceous Coleoptera and especially the number of spiders remained low in the kaolin‐treated plots.

The mechanisms allowing the widespread invasive pest Drosophila suzukii to survive from early spring until the availability of the first fruit crops are still unclear. Seasonal biology and population dynamics of D. suzukii were investigated in order to better understand the contribution of the early spring hosts to the infestation of the first fruit crops of the season. We identified hosts available to D. suzukii in early spring and assessed their suitability for the pest oviposition and reproductive success under field and laboratory conditions. The natural infestation rate of one of these hosts, Aucuba japonica, was assessed over springtime and the morphology of the flies that emerged from infested A. japonica fruits was characterized under field conditions. Then, these findings were correlated with long-term monitoring data on seasonal reproductive biology and morphology of the pest, using a cumulative degree-days (DD) analysis. Field sampling revealed that overwintered D. suzukii females were physiologically able to lay eggs at 87 DD which coincided with the detection of the first infested early spring hosts. The latter were continuously and increasingly infested by D. suzukii eggs in nature from early spring until the end of May, in particular Aucuba japonica. Individuals emerged from most of these hosts were characterized by a poor fitness and a rather low success of emergence. In the field, only few summer morphs emerged from naturally infested A. japonica fruits around the end of May-beginning of June. However, field monitoring in orchards revealed that D. suzukii individuals consisted solely of winter morphs until mid-June. These observations indicate that overwintered D. suzukii females are the predominant source for the infestations in the first available fruit crops of the season. We discuss these findings in the context of possible pest control strategies.