Spodoptera frugiperda (Lepidoptera: Noctuidae) Life Table Comparisons and Gut Microbiome Analysis Reared on Corn Varieties

SIMPLE SUMMARY: The food preference of an insect host plant affects its life cycle. The dietary needs and unique qualities of plants that act as hosts have an impact on insect pest population. Although Spodoptera frugiperda prefers maize (Zea mays), alternative crops can serve as appropriate hosts if maize crops are not easily available. Considering the six Z. mays cultivars in three different categories, “B: Heukjeom 2-ho” was found to be significantly preferred [F (5174) = 19.817; p = 0.0001] during the larval rearing stage. A metagenomic analysis of biological triplicate samples (6 × 3 = 18, 5th instar larvae reared on six corn cultivars) revealed that Firmicutes was the most prevalent bacterial community, and Proteobacteria was the second leading bacterial phylum. In terms of the bacterial genera, Enterococcus was the most prevalent, followed by Ureibacillus. To prevent the spread of this invasive pest, it is vital to gain a comprehensive understanding of FAW’s feeding preferences and gut microbial community composition. ABSTRACT: The fall armyworm (Spodoptera frugiperda, FAW) is an invasive migratory pest that has recently spread to Korea, damaging several corn cultivars with significant economic value. Comparisons of the growth stages of FAW were conducted based on the preferred feed. Therefore, we selected six maize cultivars, including three categories: (i) commercial waxy corn (mibaek 2-ho, heukjeom 2-ho, dreamoak); (ii) popcorn (oryun popcorn, oryun 2-ho); and (iii) processing corn (miheukchal). A significant effect was observed during the larvae period, pupal period, egg hatching ratio, and larvae weight, whereas the total survival period and adult period did not show significant variation among the tested corn cultivars. We identified variations in the FAW gut bacterial community that were dependent on the genotype of the corn maize feed. The identified phyla included Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. Among these genera, the most abundant bacterial genus was Enterococcus, followed by Ureibacillus. Enterococcus mundtii was the most abundant among the top 40 bacterial species. The intergenic PCR-based amplification and gene sequence of the colony isolates were also matched to the GenBank owing to the prevalence of E. mundtii. These results showed that the bacterial diversity and abundance of particular bacteria in the guts of FAWs were influenced by the six major maize corn cultivars.