The Microbial Diversity of Cabbage Pest Across Multiple Life Stages.

The cabbage root fly is a worldwide pest that causes yield losses of many common cabbage crops. The bacteria associated with are suggested to influence the pest status of their host. In this study, we characterized insect-associated bacteria of across multiple life stages and of their diet plant (turnip, subsp. ) by sequencing the V3-V4 region of 16S rRNA genes using the Illumina MiSeq platform. In total, over 1.2M paired-end reads were obtained, identifying 1006 bacterial amplicon sequence variants (ASVs) in samples obtained from the eggs, larvae, pupae and adults of , as well as turnips that were either fresh or infested with larvae. The microbial community in was dominated by , a common endosymbiont of arthropods which we found in all of the investigated insect samples, with the pupal stage having the highest relative abundance. Moderate amounts of Firmicutes were found only in adult flies, but not in previous life stages. Actinobacteria were mostly found on the eggs and on the skin of fresh plants on which the eggs were deposited. These plants also harbored a large amount of . The bacterial diversity of the healthy turnip was low, whereas the microbial community of decaying turnips that were heavily infested by larvae and showing symptoms of advanced soft rot was characterized by a high bacterial diversity. Taken together, this work provides insights into the bacterial communities associated with the cabbage pest and its associated disease symptoms.