6: Mining fruit-associated bacteria to discover novel microbial based attractants and repellents for Drosophila suzukii

Drosophila suzukii is a global pest of small fruits. It was first detected in the US (California) in 2008, has since swept across states and become major concerns for growers. Despite decades of research and pest management on D. suzukii, current controls rely exclusively on chemical insecticides, which are not effective against larvae feeding inside fruits and are not environmentally sustainable. Robust baits and trapping systems are also urgently needed to optimize D. suzukii monitoring. Drosophilid flies are frequently associated with symbiotic bacteria and yeasts in the gut, some of which can also be found on their host plants. We are interested in the extent to which the fly- and fruit-associated bacteria impact D. suzukii colonization of host fruits. We discover that D. suzukii interacts with host fruits by manipulating the fruit bacteriome. Fruits that were foraged by D. suzukii became more attractive to the flies. Surprisingly, our GC/MS data suggested that the increased attractiveness was not due to volatiles released by the bacteria introduced by the flies, but rather, increased production of specific fruit volatiles and flavor compounds in the foraged fruits. Through culturing, we have also isolated >50 bacterial species from D. suzukii and their target berry crops collected from the field. After testing 12 of these isolates, we identified a few potential fly attractant and repellent bacteria and had their volatile profiles revealed by GC/MS. Future work will include testing different candidate volatiles in isolation or mixtures in their attractiveness or repellency to D. suzukii.