Xylophagous insects represent a diverse group of species whose life cycles are trophically associated with wood at various stages of decomposition. In forest ecosystems, they play a pivotal role in wood degradation and biogeochemical nutrient cycling. Their remarkable adaptation to feeding on structurally complex and nutrient-poor woody substrates has been largely mediated by long-term symbiotic interactions with gut microbiota. This review synthesizes current knowledge on the molecular and ecological mechanisms underlying insect–microbiota interactions, with particular attention paid to the impact of environmental stressors—including elevated temperature, shifts in moisture regimes, and pollution—on microbial community structure and host adaptive responses. We critically evaluate the strength of evidence linking climate-driven microbiome shifts to functional consequences for the host and the ecosystem. The ecological implications of microbiota restructuring, such as impaired wood decomposition, decreased disease resistance, facilitation of xylophagous species spread, and alterations in key biotic interactions within forest biocenoses, are discussed. Particular emphasis is placed on the integration of multi-omics technologies and functional assays for a deeper, mechanistic understanding of microbiota roles. We also assess the potential and limitations of microbiome-based approaches for insect population management, with the overall goal of maintaining and enhancing the resilience of forest ecosystems under ongoing climate change.

Based on our own field data and using modeling of modern potential ranges (in the MaxEnt program), an assessment of the spatial distribution of the rare representative of the longhorn beetle family, Callipogon (Eoxenus) relictus Semenov 1899, was conducted in northeast Asia (220 geographic locations). The generated maps of the potential range of C. relictus demonstrate a high likelihood of the species’ presence in the upland areas of southern far east Russia, the provinces of northeastern China, and the Korean Peninsula. Field data also indicate the extensive association of the species with undisturbed broadleaf and coniferous–broadleaf forests in northeast Asia. Maps of the potential distribution of C. relictus in northeast Asia have been compiled based on four climate change scenarios from the present time to 2070. Under all of the climate scenarios used, it is shown that suitable habitats for the species will persist in certain areas of Primorsky Krai, as well as neighboring provinces of the People’s Republic of China and a small enclave on the Korean Peninsula in Gangwon-do province. Significant reduction in suitable conditions for the rare longhorn beetle will occur in the rest of its distribution range.

Gut microbes are important for saproxylophagous insects, but little is known about the specific types of microbes that we can grow in the lab and how their diet affects them. We characterized aerobic culturable microbes from the superworm Zophobas atratus larvae reared on a standard diet (SD) and a fungal-based diet (FD) using the selective plating and 16S rRNA sequencing of isolates. Five functional groups were cultured: amino acid autotrophs, enterobacteria, yeasts, cellulolytic bacteria, and molds. A quantitative assessment revealed distinct diet-dependent patterns: SD-fed larvae showed the dominance of enterobacteria and amino acid autotrophs, while FD-fed larvae exhibited a higher abundance of enterobacteria and yeasts. Mold populations remained minimal under both diets. A phylogenetic analysis of bacterial isolates showed four core bacterial phyla (Pseudomonadota, Actinobacteria, Bacillota, and Bacteroidota) with diet-sensitive genus-level variations. Pseudomonadota dominated both diets, but certain genera were associated with different diets: Micrococcus and Brucella in the SD versus Citrobacter and Pseudomonas in the FD. Shared genera (Klebsiella, Enterobacter, and Bacillus) may represent a core culturable community. These findings demonstrate the influence of diet on culturable gut microbes while highlighting the need for complementary molecular approaches to study unculturable taxa. The isolated strains provide resources for investigating microbial functions in insect nutrition.

The rearing of saproxylic insects in laboratory conditions is an important task for studying the biology of insects. Through understanding nutritional needs, it is possible to optimize beetle rearing in laboratory conditions. In this study, an artificial fungi-based diet (FD) was developed for the cultivation of the darkling beetle Zophobas atratus (Fabricius, 1775) (Coleoptera: Tenebrionidae) in laboratory conditions as a model object for studying the biology of saproxylophagous beetles. To assess the influence of the diet, a number of physiological parameters were measured, including development time, body size, and weight of all stages of the beetle’s life cycle, as well as its immune status. The immune status of Z. atratus was assessed on the basis of larval hemolymph antibacterial activity against six different bacterial strains assessed using disk-diffusion and photometric tests. Our findings show that the FD reduces development time and boosts the immune status as compared to beetles reared on a standard diet (SD). Samples from FD-reared larvae had pronounced antibacterial activity as compared to samples from SD-reared larvae. This work is of fundamental importance for understanding the correlations between nutrition and development of saproxylic Coleoptera and is the first report on immune status regulation in this group of insects.

Data on carbon dioxide emissions from soils in oak and Korean pine-broadleaf forests of the southern Sikhote-Alin were obtained during the 2023–2025 study period. Differences in the average monthly CO2 emission rates across seasons were characterized in the Haplic Cambisols of the investigated forest ecosystems. Forests growing under conditions of a temperate monsoon climate exhibit a specific soil respiration regime, characterized by a high proportion of summer flux (over 50%) and high emission values during the early autumn months. The highest parameters of total CO2 fluxes were observed in autumn (September, October), which is associated with favorable hydrothermal conditions for microflora activity during this period. The highest carbon losses over the study period were recorded in oak forests, amounting to 673.59 g C m⁻², while the annual total CO2 flux in Korean pine forests was 617.10 g C m⁻².

The gut microbiome of Callipogon relictus, a rare member of the family Cerambycidae, was characterized for the first time using shotgun metagenomic sequencing. The aim of this study was to compare the taxonomic diversity and structure of the gut microbial communities in larvae and adults. Bacteria dominated the metagenomic profiles, accounting for 92.47% of the taxonomic composition in adults and 85.31% in larvae. Proteobacteria predominated in the bacterial component of both pooled profiles, accounting for 87.88% and 89.43%, respectively. The pooled adult profile had the highest relative abundances of Gammaproteobacteria and Enterobacterales, whereas the pooled larval profile had higher relative abundances of Alphaproteobacteria and Rickettsiales. In the pooled samples analyzed, 155 bacterial and 69 fungal genera were detected in the larval profile, compared with 85 and 17 genera, respectively, in the adult profile; the fungal component accounted for 10.46% of the larval profile and 0.18% of the adult profile. The two profiles shared 77 bacterial, 17 fungal, and 15 protist genera. The virus-like/retroelement sequence fraction was dominated by sequences related to Errantivirus, a member of the family Metaviridae. Because Metaviridae comprise LTR retrotransposons, this signal was interpreted as endogenous retroelement DNA rather than evidence of a free-virus gut virome. These results provide a preliminary description of a shared bacterial core accompanied by differences between the pooled profiles in lower-rank bacterial composition and in the structure of the fungal and protist components of the C. relictus microbiome.