Abstract
Drosophila suzukii (Matsumura) is a global invasive pest of soft and stone fruits, where adult females with serrated ovipositor penetrate healthy, ripening and ripe fruit. Most common conventional-chemical approach for D. suzukii management, faced stringent pesticide regulations and repetitive applications, raising concerns about resistant populations and pesticide residues in fruits. This PhD thesis explores a sustainable novel attract-and-kill approach employing yeast-based formulation as attractant combined with an insecticide. I evaluated the attract-and-kill strategy by using the yeast Hanseniaspora uvarum combined with insecticide spinosad in cherry trials. Application on an 80 cm wide strip of the tree canopy at 1 m height was compared to conventional insecticide treatment and an unsprayed control. The D. suzukii infestation rates were validated by fruit sampling. Then, I investigated the D. suzukii attractancy to the less-known yeast Saccharomycopsis vini formulated as a supernatant and compared it with H. uvarum in a Y-maze olfactometer choice trial. A vineyard and cherry field trial followed, where both formulations were combined and applied with insecticide spinosad. Infestation rates were validated from sampled fruits and compared with unsprayed control. Lastly, I explored entomopathogenic fungi (EPF) as an alternative to insecticides. Mortality of D. suzukii exposed to blueberries treated with spore suspension of Beauveria bassiana CAN, Metarhizium anisopliae DSM1490, Metarhizium brunneum GC2I, and Metarhizium brunneum CB15 was evaluated. The interaction between D. suzukii and EPF was further investigated with Y-maze olfactometer, gas chromatography-mass spectrometry (GC-MS) of sampled EPF Volatile Organic Compounds (VOCs), gas chromatography-electroantennographic detector (GC-EAD), and electroantennography (EAG) dose-response trials. M. brunneum GC2I exhibited the highest mortality rate, acting also as an attractant in the olfactometer trial, with flies’ antennae activity on a few fungi VOCs. In contrasts, M. anisopliae DSM1490 displayed the lowest mortality, acting as a repellent in the olfactometer trial, verified by flies’ antennae activity on specific fungi VOCs. Findings obtained from this PhD thesis provide a supporting background for a new, sustainable, environmentally friendly approach for D. suzukii management.