Scelimeninae is a key member of the pygmy grasshopper community, and an important ecological indicator. No mitochondrial genomes of Scelimeninae have been reported to date, and the monophyly of Scelimeninae and its phylogenetic relationship within Tetrigidae is still unclear. We sequenced and analyzed eight nearly complete mitochondrial genomes representing eight genera of Scelimeninae. These mitogenomes ranged in size from 13,112 to 16,380 bp and the order of tRNA genes between COII and ATP8 was reversed compared with the ancestral order of insects. The protein-coding genes (PCGs) of tetrigid species mainly with the typical ATN codons and most terminated with complete (TAA or TAG) stop codons. Analyses of pairwise genetic distances showed that ATP8 was the least conserved gene within Tetrigidae, while COI was the most conserved. The longest intergenic spacer (IGS) region in the mitogenomes was always found between tRNA^Ser(UCN) and ND1. Additionally, tandem repeat units were identified in the longest IGS of three mitogenomes. Maximum likelihood (ML) and Bayesian Inference (BI) analyses based on the two datasets supported the monophyly of Tetriginae. Scelimeninae was classified as a non-monophyletic subfamily.

Heavy metal pollution in the environment is mostly manifested as a multi-elemental compound pollution. The effect of the long-term exposure to heavy metal pollution on the gut microbes of insects has remained unknown. For the current work, the population of Eucriotettix oculatus living in mining areas around the Diaojiang River with a history of hundreds of years of pollution, was selected along with the similar species living in non-mining areas to conduct a comparative study of their gut microbes. The microbial communities were analyzed using 16S rRNA amplicon sequencing. The results showed Proteobacteria to be dominant among gut microbes of E. oculatus, but the abundance of Proteobacteria was significantly increased when the insects were exposed to the environment with heavy metal pollution. The symbiotic bacteria belonging to genus Wolbachia were found to be dominant among the insect population from the non-mining area group, while the pathogenic bacteria belonging to Aeromonas were dominant among the insect population of the mining area group. The diversity analysis showed that the gut microbial community diversity of E. oculatus was reduced in the heavy metal pollution habitat. The analysis of the differences in the gut microbial population and metabolic pathways of the two groups showed that the heavy metal pollution caused the increase in pathogenic bacteria among the gut microbes of E. oculatus, which might have a negative impact on the health of the host. At the same time, probiotics and the beneficial metabolism pathways were also found to increase and enhance, helping the host to resist the damage caused by heavy metal stress. This might be one of the strategies used by E. oculatus to adapt to heavy metal pollution.

The mitochondrial genome (mitogenome) of Saussurella borneensis (Orthoptera: Tetrigoidea) was determined and analyzed. The complete mitochondrial genome is 16,006 bp in length, consisting of 37 genes, including 13 protein-coding (PCGs), 22 tRNA, 2 rRNA genes as well as an A + T-rich region. Ten PCGs initiated with a typical ATN codon (one with ATC, two with ATA, two with ATT, and five with ATG) and 13 terminated with complete stop codons. The overall nucleotide composition was 42.97% for A, 17.61% for C, 11.62% for G, and 27.8% for T. Phylogenetic analysis of S. borneensis fully resolved it in a basal branch sister to Tripetaloceroides tonkinensis. This data increase the bioinformatics of the Tetrigidae, and improves our understanding of the phylogenetic status of S. borneensis in the Tetrigoidea.

The nearly complete mitochondrial genome (mitogenome) of Teredorus nigropennis was determined and analyzed. This mitogenome was 14,652 bp in size and encoded 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes. The most common start codon is ATN, the most common termination codon is TAA and two genes have incomplete termination codon T (TA). The overall nucleotide composition was 45.2% of A, 10.2% of G, 28.6% of T, and 16.1% of C. The data will increase the basic information of Tetrigidae phylogenetic research and can help to better understand the phylogenetic status of T. nigropennis in Tetrigiodea.

The gut microbiome significantly influences the health and productivity of silkworms (Bombyx mori), the cornerstone of sericulture. With the increasing use of cost-effective artificial diets in sericulture, it is crucial to understand how these diets impact the silkworm gut microbiomes. Here we employed 16S rRNA sequencing to delineate the impact of three distinct dietary regimens on the silkworm gut microbiomes: exclusive mulberry leaf diet (SY), exclusive artificial feed diet (SL), and a sequential transition from artificial feed to mulberry leaves (ZS). Our results unveiled stark differences in microbial diversity across the groups, with the ZS group displaying an intermediary complexity. LefSe and random forest analyses identified Methylobacteriaceae, Microbacterium, and Rhodococcus as significantly enriched in the ZS group, suggesting their potential to facilitate silkworms’ adaptation to dietary transitions. Functional profiling revealed differential pathway regulation, indicating a metabolic reconfiguration in response to dietary modulations. Notably, the enrichment of Lactobacillus and Weissella in both the SL and ZS groups highlights their potential as probiotics in artificial diets. Our findings provide insights into the diet adaptation mechanisms of silkworm gut microbiota, paving the way for harnessing the intestinal bacteria to enhance silkworm health and silk production through targeted microbial interventions in sericulture practices.

The genus Scelimena Serville (Orthoptera: Tetrigidae) from China is reviewed. One species, Scelimena spicupennis Zheng & Ou, 2003 (China: Yunnan) is redescribed, and a new record of Scelimena discalis (Hancock, 1915) from China is given. An annotated identification key for Chinese species of the genus Scelimena is provided. Mitochondrial genes of S. spicupennis and S. discalis were sequenced and annotated. The sizes of the two sequenced mitogenomes are 17,552 bp (S. discalis), and 16,069 bp (S. spicupennis), respectively. All of the PCGs started with the typical ATN (ATT, ATC or ATG) or TTG codon and most ended with complete TAA or TAG codon, with the exception of the ND5 gene, which terminated with an incomplete T. The mitochondrial genomes for these two recorded species are provided, and the constructed phylogenetic tree supports their morphological taxonomic classification. The topology of the phylogenetic tree showed that three species of Scelimena were clustered into one branch and formed a monophyletic and a holophyletic group.