The Portuguese Blueberry valley calls for an immediate action plan towards Drosophila suzukii

Abstract: Drosophila suzukii is an invasive pest responsible for significant economic losses
worldwide, particularly in soft-skinned fruit crops such as blueberries. Recognized as one of
the most destructive agricultural pests, its rapid reproductive rate and ability to inflict extensive crop damage make it especially problematic. In the Portuguese municipality of Sever do Vouga, blueberry production accounts for nearly 80 % of agricultural output; for this reason, D. suzukii poses a severe threat to the local economy, with documented yield losses of 30-40 %. The region’s ideal edaphoclimatic conditions, which position it as one of Europe’s premier blueberry-growing areas, further exacerbate the impact of D. suzukii infestations.
Currently, the bioecology of D. suzukii in Sever do Vouga is not fully understood, nor is its
relationship with the local ecosystem or the presence of potential alternative wild hosts. Given consumer demand for healthier, sustainably grown foods and the region’s proximity to protected natural areas, there is a pressing need to explore biological control measures to curb losses while maximizing the “Blue Valley’s” agricultural potential. Here, we outline our preliminary work in collaboration with Mirtilusa, a company representing several local blueberry producers.
We surveyed several reported wild host species in the region, including Rubus ulmifolius,
Lonicera periclymenum, Dioscorea communis, Smilax aspera, and uncollected late-season
blueberries. The exclusive presence of D. suzukii larvae in blueberry-infested fruits suggests
two potential ecological scenarios: either populations persist until the final blueberries remain available in the field, or the flies utilize alternative hosts beyond those examined in this study – including species located outside immediate orchard boundaries. Notably, we
documented the presence of the parasitoid Trichopria drosophilae Perkins (Hymenoptera:
Diapriidae), indicating potential natural biological control within the system. These initial steps provide a foundational understanding of D. suzukii’s regional biology and ecology – knowledge essential for designing science-based, environmentally sound biological control strategies that align with the EU Green Deal framework for sustainable agriculture.