Species distribution models of the Spotted Wing Drosophila (Drosophila suzukii, Diptera: Drosophilidae) in its native and invasive range reveal an ecological niche shift

The Spotted Wing Drosophila (Drosophila suzukii) is native to Southeast Asia. Since its first detection in 2008 in Europe and North America, it has been a pest to the fruit production industry as it feeds and oviposits on ripening fruit. Here we aim to model the potential geographical distribution of D. suzukii. We performed an extensive literature review to map the current records. In total 517 documented occurrences (96 native and 421 invasive) were identified, spanning 52 countries. Next, we constructed three species distribution models (SDMs) based on occurrence records in: (a) the native range (SDMnative), (b) the invasive range in Europe (SDMEurope), and (c) a global model of all records (SDMglobal). The aim of the models was to investigate whether this species will be able to occupy additional ecological niches beyond its native range and expand its current geographic distribution both globally and in Europe. The SDMs were generated using Maximum Entropy algorithms (Maxent) based on present occurrence records and bioclimatic variables (WorldClim). Predictions of habitat suitability vary greatly depending on origins of occurrence records. According to all models, precipitation and low temperatures were key limiting factors for the distribution of D. suzukii, which suggests that this species requires a humid environment with mild winters in order to establish a permanent population in its invasive range. Several regions in the invasive range, not presently occupied by this species, were predicted highly suitable, especially in northern Europe, suggesting that D. suzukii does not yet occupy its full fundamental niche. Synthesis and applications. Based on these models of potential geographic distribution of the Spotted Wing Drosophila (Drosophila suzukii), we show a shift in the ecological niche in Drosophila suzukii populations, emphasizing the importance of using presence, and local environmental data. Further investigation regarding new occurrences is recommended to secure optimal pest management. Despite a continuing expansion, many countries still lack proper surveillance schemes, and we urge policy makers to initiate appropriate management programmes.