Developmental Shifts in the Microbiome of a Cosmopolitan Pest: Unraveling the Role of and Dominant Bacteria.

bacteria (phylum Proteobacteria) are ubiquitous intracellular parasites of diverse invertebrates. In insects, coevolution has forged mutualistic associations with species, influencing reproduction, immunity, development, pathogen resistance, and overall fitness. However, the impact of on other microbial associates within the insect microbiome, which are crucial for host fitness, remains less explored. The diamondback moth (), a major pest of cruciferous vegetables worldwide, harbors the dominant strain , known to distort its sex ratio. This study investigated the bacterial community diversity and dynamics across different developmental life stages and infection states in using high-throughput 16S rDNA amplicon sequencing. Proteobacteria and Firmicutes dominated the microbiome regardless of life stage or infection. However, the relative abundance of dominant genera, including an unclassified genus of Enterobacteriaceae, , , and , displayed significant stage-specific variations. While significant differences in bacterial diversity and composition were observed across life stages, infection had no substantial impact on overall diversity. Nonetheless, relative abundances of specific genera differed between infection states. Notably, exhibited a stable, high relative abundance across all stages and negatively correlated with an unclassified genus of Enterobacteriaceae, , and . Our findings provide a foundational understanding of the complex interplay between the host, , and the associated microbiome in , paving the way for a deeper understanding of their complex interactions and potential implications for pest control strategies.