Open access publications in the SLU publication database

Abstract

Investigating the factors that determine the behaviour of new pests is essential for understanding, predicting and managing their impact on natural and agricultural ecosystems. The spotted wing drosophila (SWD), Drosophila suzukii (Matsumura; Diptera: Drosophilidae), is a worldwide spreading polyphagous pest of soft fruit and berries. Drosophila suzukii is capable to oviposit and develop in ripening fruit, which represents an ecological host shift relative to Drosophila species that prefer overripe fruit. Notably, D. suzukii lives in close association with yeasts, like saprophagous Drosophila flies, but the ecological relevance of this association is insufficiently understood. Chemical cues are important when D. suzukii exploits fruit as a niche. Chemosensory adaptations allow D. suzukii to detect chemical cues emitted by ripening and overripe host fruits. Host attraction, consequently, is odour-guided and precedes egg-laying and exploitation of fruit as the larval niche. However, it is not clear to which extent fruit ripeness, presence of yeast, or sex and mating state of the flies, modulate attraction and host choice. This thesis demonstrates: (i) D. suzukii host choice is modulated by fruit ripeness and fly mating, (ii) a reciprocal niche construction and mutualistic interaction between D. suzukii and the yeast Hanseniaspora uvarum (Niehaus; Ascomycota: Saccharomyceta) on fresh fruit, (iii) the D. suzukii-H. uvarum association can be exploited for the development of lures to monitor and control the invasive pest. The collective findings advance our fundamental understanding of D. suzukii host choice decisions and niche construction. This understanding is of relevance for the development of new pest management tools such as manipulation of insect behaviour.