A roadmap to key traits of invasive Drosophilidae

Biological invasions have intensified in recent decades, mostly driven by international trade and travel, raising significant concerns, particularly regarding insect pests. Once non-native species establish, they can disrupt natural ecosystem stability, undermine agroecosystem sustainability and cause substantial economic losses. The urgency to anticipate these socio-economic impacts has accelerated research into the traits and processes that predispose certain species to invasion success. Our review examines the factors contributing to invasion success, using the well-documented case of Drosophilidae as a model taxon given the extensive literature on this family. The invasion of Drosophila suzukii is the most well studied, yet it represents just one example among several Drosophilidae successful invasions, including those from the genera Drosophila, Scaptomyza and Zaprionus. Their traits and adaptive capacities have enabled them to overcome environmental barriers, facilitating their global spread and establishment. We first explore the selective forces acting on pioneer individuals and their ability to establish reproducing populations. We then analyse the roles of abiotic factors (through phenotypic plasticity, tolerance to thermal and water stress, synergies between multiple stressors) and biotic factors (through the exploitation of novel trophic niches, resistance to competition and predation, symbiont-mediated assistance) in shaping invasion success. A nuanced understanding of how these constraints interact is essential for predicting and managing the proliferation of invasive Drosophilidae and other non-native species. We propose that successful invasive species do not necessarily excel in one single trait but rather perform adequately across multiple traits and processes. In this review, we found support in the literature for 14 key traits and processes of Drosophilidae biology that facilitate a species' ability to become invasive and provide future perspectives to address critical knowledge gaps, paving the way towards a comprehensive understanding of invasion success.