Epsilon Archive for Student Projects

Abstract

Drosophila suzukii is a serious pest of soft skin fruit and berries. Despite D. suzukii niche to lay eggs in ripening fruit, they seem to have a similar association with yeast as other drosophilids. Yeast provides larvae and adult flies with essential nutrients and the flies contribute to yeast dispersal when moving between plants. Like other drosophilds D. suzukii is believed to have an association with a specific yeast flora where Hanseniaspora uvarum is known to be the predominant species. The object of this thesis has been to investigate the impact of microbial volatiles from the associated yeast H. uvarum in mating and oviposition choices for D. suzukii.

In a no-choice assay, individual couples of virgin D. suzukii flies exposed to volatiles from H. uvarum were more likely to mate during the 30-minute experiment compared to the blank control. In a second experiment to assay the effect of the minimal growth media and higher relative humidity in the H. uvarum treatment we got a weak response and no difference between treatments and control suggesting that further experiments should be conducted for solid results. Volatiles from H. uvarum or raspberries, or a combination of these, was found to evoke oviposition to an equally high extent in mated D. suzukii in absence of visual cues compared to the control. The results indicate that D. suzukii uses volatile microbial cues when deciding to mate and oviposit.