Effect of Different Host Plants on the Diversity of Gut Bacterial Communities of Spodoptera frugiperda (J. E. Smith, 1797)

SIMPLE SUMMARY: The gut microbes are important to the insect physiology and behavior. Spodoptera frugiperda (J. E. Smith) is a worldwide migratory invasive and polyphagous pest, which causes great damage to various host crops in China. The structures of gut bacterial community of S. frugiperda feeding on different host plants are largely unexplored. In this study, high-throughput sequencing was used to compare the gut bacterial communities of S. frugiperda reared on different host plants. The results confirmed that the host plants can significantly affect the gut bacterial diversity and structure of S. frugiperda. This study lays a foundation for further studies on the function of gut bacteria of S. frugiperda and its adaptive mechanism to the host. ABSTRACT: Intestinal symbiotic bacteria have formed an interdependent symbiotic relationship with many insect species after long-term coevolution, which plays a critical role in host growth and adaptation. Spodoptera frugiperda (J. E. Smith) is a worldwide significant migratory invasive pest. As a polyphagous pest, S. frugiperda can harm more than 350 plants and poses a severe threat to food security and agricultural production. In this study, 16S rRNA high-throughput sequencing technology was used to analyze the diversity and structure of the gut bacteria of this pest feeding on six diets (maize, wheat, rice, honeysuckle flowers, honeysuckle leaves, and Chinese yam). The results showed that the S. frugiperda fed on rice had the highest bacterial richness and diversity, whereas the larvae fed on honeysuckle flowers had the lowest abundance and diversity of gut bacterial communities. Firmicutes, Actinobacteriota, and Proteobacteria were the most dominant bacterial phyla. PICRUSt2 analysis indicated that most of the functional prediction categories were concentrated in metabolic bacteria. Our results confirmed that the gut bacterial diversity and community composition of S. frugiperda were affected significantly by host diets. This study provided a theoretical basis for clarifying the host adaptation mechanism of S. frugiperda, which also provided a new direction to improve polyphagous pest management strategies.