Identification of entomopathogenic bacteria associated with the invasive pest Drosophila suzukii in infested areas of Germany

The invasive insect pest Drosophila suzukii causes extensive damage to soft-skinned fruit crops as they ripen. Current control methods involve the application of chemical pesticides, but this approach is ineffective and environmentally hazardous. To investigate the potential of bacterial pathogens carried by D. suzukii as biocontrol agents, we characterized bacteria associated with D. suzukii larvae in two parts of Hesse, Germany, by collecting infested fruits and culturing individual bacteria from moribund specimens for taxonomic classification by 16S rDNA sequencing. Among the bacteria we detected, some had a detrimental effect on the host whereas others were neutral or beneficial. When the detrimental and beneficial bacteria were presented simultaneously, we observed complex tripartite interactions that modulated the insect's innate immune response. Our study provides insight into the complex relationships within the microbiome and pathobiome of D. suzukii and may le ad to the isolation of bacteria that can be used as biological control agents.