The fruit-microbe-fly interactions: How Drosophila suzukii foraging modifies the fruit microbiome and generates a feedback loop to fly attraction

Many insect-microbe associations are open systems, characterized by the exchange of microbes between hosts and their external environment. Particularly, microbial transmission via insect foraging on food substrates is a prevalent phenomenon; however, how different microbial communities influence each other during insect-plant(food) interactions and the resulting reciprocal effects on the host organisms remains unclear.

Studies on Drosophila melanogaster have shown that its microbiome can influence the fly’s attraction to food substrates through the emission of volatiles. However, much less is known for D. suzukii, a major agricultural pest closely related to D. melanogaster. In this study, we investigate how D. suzukii foraging on fruit affects the fruit microbiome and its subsequent impact on fly-fruit interactions.

We conducted 16S rRNA gene amplicon sequencing and colony forming unit (CFU) assays to compare the microbiomes composition and microbial load between unvisited and foraged fruits. The attractiveness of the fruits to D. suzukii was evaluted using the two-choice trap assay, open-choice preference assay, and video tracking. In addition, we used GC-MS to identify the chemicals emitted by fruit foraged by D. suzukii that improve their attractiveness to the flies. Our findings suggest that fly-associated bacteria can modify fly-fruit attractions by restructuring the fruit microbiome and volatile profiles.