Interactions between temperature and environmental variables in Drosophila suzukii

Drosophila suzukii Matzumura (Diptera: Drosophilidae) is an invasive species that became a pest of soft and stone fruits since its appearance in Southern Europe in 2008. Within Drosophila species, D. suzukii is the main cause of economic damage in fruit production. This is because the female, thanks to a serrated type of ovipositor, lays eggs in ripening fruit of many plant species, and the larvae rapidly consume the fruit. My PhD programme is aimed at providing concrete answers to farmers regarding the response of D. suzukii to temperature and based on the performance of D. suzukii with respect to Wolbachia, pesticides efficacy, and fruit infestation under variable temperature. The dissertation consists of four parts. The first part (chapter 1) introduces the background knowledge on D. suzukii, in relation to its spread, biology, pest status, and management options. The second part (chapter 2) assesses the impact of temperature and Wolbachia infection on the fitness of D. suzukii, with special attention to nutritional stress, survival, fecundity, cytoplasmic incompatibility and viability. The third part (chapter 3) investigates the effect of temperature on the efficacy of four groups of pesticides on the mortality of D. suzukii and its performance on different fruits under field and laboratory conditions. The fourth part (chapter 4) examines the influence of short cold temperature stress on the development of D. suzukii in different fruits. All together, the findings provide information for the improvement of the management of D. suzukii in fruit orchards of north-eastern Italy, emphasizing the role of some environmental variables such as temperature.