Gut bacterial community structure shifts in successive generations of Spodoptera exigua under short-term thermal stress

Long-term studies that advance our mechanistic understanding of gut bacterial symbionts of insect hosts in response to the successive generations of short-term thermal stress are lacking. The beet armyworm, Spodoptera exigua is a notorious agricultural pest worldwide and has often experienced stressful temperature fluctuations in field environments. In this study, 1,795,224 reads and 2,565 operational taxonomic units (OTUs) were detected in 23 gut samples of S. exigua fed for five successive generations using 16S rRNA high-throughput sequencing technology. Overall, we identified 618 bacterial genera from 30 phyla, and Proteobacteria and Firmicutes were the most dominant phyla. Alpha-diversity of gut microbiome revealed significant differences among these generation treatment groups. We detected the highest bacterial richness and alpha diversity in the fifth generation and the lowest in the first generation under short-term thermal stress. Beta diversity indicated that the gut microbial ...