Insect gut microbes have important roles in host feeding, digestion, immunity, development, and coevolution with pests. The fall armyworm, Spodoptera frugiperda (Smith, 1797), is a major migratory agricultural pest worldwide. The effects of host plant on the pest’s gut bacteria remain to be investigated to better understand their coevolution. In this study, differences in the gut bacterial communities were examined for the fifth and sixth instar larvae of S. frugiperda fed on leaves of different host plants (corn, sorghum, highland barley, and citrus). The 16S rDNA full-length amplification and sequencing method was used to determine the abundance and diversity of gut bacteria in larval intestines. The highest richness and diversity of gut bacteria were in corn-fed fifth instar larvae, whereas in sixth instar larvae, the richness and diversity were higher when larvae were fed by other crops. Firmicutes and Proteobacteria were dominant phyla in gut bacterial communities of fifth and sixth instar larvae. According to the LDA Effect Size (LEfSe) analysis, the host plants had important effects on the structure of gut bacterial communities in S. frugiperda. In the PICRUSt2 analysis, most predicted functional categories were associated with metabolism. Thus, the host plant species attacked by S. frugiperda larvae can affect their gut bacterial communities, and such changes are likely important in the adaptive evolution of S. frugiperda to host plants.

Anoplophora glabripennis (Motschulsky, 1854) and Demonax pseudonotabilis Gressitt & Rondon, 1970 are two commonly found longicorn beetles from China. However, the lack of sufficient molecular data hinders the understanding of their evolution and phylogenetic relationships with other species of Cerambycidae. This study sequenced and assembled the complete mitochondrial genomes of the two species using the next-generation sequencing method. The mitogenomes of A. glabripennis and D. pseudonotabilis are 15,622 bp and 15,527 bp in length, respectively. The mitochondrial gene content and gene order of A. glabripennis and D. pseudonotabilis are highly conserved with other sequenced longicorn beetles. The calculation of nonsynonymous (Ka) and synonymous (Ks) substitution rates in PCGs indicated the existence of purifying selection in the two longicorn beetles. The phylogenetic analysis was conducted using the protein-coding gene sequences from available mitogenomes of Cerambycidae. The two species sequenced in this study are, respectively, grouped with their relatives from the same subfamily. The monophyly of Cerambycinae, Dorcasominae, Lamiinae, and Necydalinae was well-supported, whereas Lepturinae, Prioninae, and Spondylidinae were recovered as paraphyletic.

Haplodiplatyidae is a recently established earwig family with over 40 species representing a single genus, Haplodiplatys Hincks, 1955. The morphology of Haplodiplatyidae has been studied in detail, but its molecular characters remain unclear. In this study, two mitogenomes of Haplodiplatys aotouensis Ma & Chen, 1991, were sequenced based on two samples from Fujian and Jiangxi provinces, respectively. These represent the first mitogenomes for the family Haplodiplatyidae. The next-generation sequencing method and subsequent automatic assembly obtained two mitogenomes. The two mitogenomes of H. aotouensis were generally identical but still exhibit a few sequence differences involving protein-coding genes (PCGs), ribosomal RNA (rRNA) genes, control regions, and intergenic spacers. The typical set of 37 mitochondrial genes was annotated, while many transfer RNA (tRNA) genes were rearranged from their ancestral locations. The calculation of nonsynonymous (Ka) and synonymous (Ks) substitution rates in PCGs indicated the fastest evolving nd4l gene in H. aotouensis. The phylogenetic analyses supported the basal position of Apachyidae but also recovered several controversial clades.