Distinct gut bacterial composition in Anoplophora glabripennis reared on two host plants

The Correlation between the Gut Microbiota of Endoclita signifer (Lepidoptera, Hepialidae) Larvae and Their Host Preferences

Insects' gut microbiota plays a crucial role in their host selection, adaptation, and plasticity. This study explored the impact of gut bacteria on the adaptation of host selection under different stresses (diverse feeding preferences and no feeding preferences). The seventh instar E. signifer larvae were artificially transferred from the most-selected host E. grandis × E. urophylla (Es) to more preferred hosts, M. apelta (Ma), as well as the non-preferred host, B. papyrifera (Bp). We then obtained the larval gut of three different feeding preference hosts. The gut bacterial DNA was sequenced and analyzed based on 16S rRNA. There were significant differences in the composition of dominant gut bacteria between Es with Ma and Bp, but without significant differences between Ma and Bp. In the process, Burkholderia and Microbacillus with degrading pesticides had significant changes, and Enterococcus with insect gut probiotics also had significant changes. The presence of enterococcus may be one of the main causes of intestinal microbiota changes before and after host transfer. Notably, when the feeding of E. signifer changes, the complex connections that exist between gut bacteria also change. Additionally, there was a negative correlation between the feeding preferences of E. signifer and the metabolic functions of their gut bacteria. This study provided a theoretical basis for the prediction and use of gut bacteria to interfere with the feeding of E. signifer.

Changes in the gut bacterial community affect miRNA profiles in Riptortus pedestris under different rearing conditions

Insects possess complex and dynamic gut microbial system, which contributes to host nutrient absorption, reproduction, energy metabolism, and protection against stress. However, there are limited data on interactions of host-gut bacterial microbiota through miRNA (microRNA) regulation in a significant pest, Riptortus pedestris. Here, we performed the 16S rRNA amplicon sequencing and small RNA sequencing from the R. pedestris gut under three environmental conditions and antibiotic treatment, suggesting that we obtained a large amount of reads by assembly, filtration and quality control. The 16S rRNA amplicon sequencing results showed that the abundance and diversity of gut bacterial microbiota were significantly changed between antibiotic treatment and other groups, and they are involved in metabolism and biosynthesis-related function based on functional prediction. Furthermore, we identified different numbers of differentially expressed unigenes (DEGs) and differentially expressed miRNAs (DEMs) based on high-quality mappable reads, which were enriched in various immune-related pathways, including Toll-like receptor, RIG-I-like receptor, NOD-like receptor, JAK/STAT, PI3K/Akt, NF-κB, MAPK signaling pathways, and so forth, using GO and KEGG enrichment analysis. Later on, the identified miRNAs and their target genes in the R. pedestris gut were predicted and randomly selected to construct an interaction network. Finally, our study indicated that alterations in the gut bacterial microbiota are significantly positively or negatively associated with DEMs of the Toll/Imd signaling pathway with Pearson correlation analysis. Taken together, the results of our study lay the foundation for further deeply understanding the interactions between the gut microbiota and immune responses in R. pedestris through miRNA regulation, and provide the new basis for pest management in hemipteran pests.