Background: Carbon dioxide (CO₂) is a pervasive chemical stimulus that plays a critical role in insect life, eliciting behavioral and physiological responses across different species. High CO₂concentration is a major feature of termite nests, which may be used as a cue for locating their nests. Termites also survive under an elevated CO₂concentration. However, the mechanism by which elevated CO₂concentration influences gene expression in termites is poorly understood.Methods: To gain a better understanding of the molecular basis involved in the adaptation to CO₂concentration, a transcriptome ofCoptotermes formosanusShiraki was constructed to assemble the reference genes, followed by comparative transcriptomic analyses across different CO₂concentration (0.04%, 0.4%, 4% and 40%) treatments.Results: (1) Based on a high throughput sequencing platform, we obtained approximately 20 GB of clean data and revealed 189,421 unigenes, with a mean length and an N50 length of 629 bp and 974 bp, respectively. (2) The transcriptomic response ofC. formosanusto elevated CO₂levels presented discontinuous changes. Comparative analysis of the transcriptomes revealed 2,936 genes regulated among 0.04%, 0.4%, 4% and 40% CO₂concentration treatments, 909 genes derived from termites and 2,027 from gut symbionts. Genes derived from termites appears selectively activated under 4% CO₂level. In 40% CO₂level, most of the down-regulated genes were derived from symbionts. (3) Through similarity searches to data from other species, a number of protein sequences putatively involved in chemosensory reception were identified and characterized inC. formosanus, including odorant receptors, gustatory receptors, ionotropic receptors, odorant binding proteins, and chemosensory proteins.Discussion: We found that most genes associated with carbohydrate metabolism, energy metabolism, and genetic information processing were regulated under different CO₂concentrations. Results suggested that termites adapt to ∼4% CO₂level and their gut symbionts may be killed under high CO₂level. We anticipate that our findings provide insights into the transcriptome dynamics of CO₂responses in termites and form the basis to gain a better understanding of regulatory networks.

Cheirotonus jansoni (Jordan, 1898), a beetle species of ecological and ornamental significance, is predominantly found in southern China. With limited dispersal ability, it is classified as a Class 2 protected species in China. In this study, the widely employed maximum entropy (MaxEnt) model and the ensemble Biomod2 model were applied to simulate C. jansoni habitat suitability in China under current environmental conditions based on available distribution data and multiple environmental variables. The optimized MaxEnt model demonstrated improved accuracy and robust predictive capabilities, making it the preferred choice for simulating dynamic changes in potentially suitable habitats for C. jansoni under future climate scenarios. Protection gaps were further identified through analyses of the overlap between nature reserves and highly suitable areas for C. jansoni. The established models indicated that this species primarily resides in southeastern mountainous regions of China below 2000 m, with a preferred altitude of 1000–2000 m. Future climate scenarios suggest a reduction in the overall suitable habitat for C. jansoni with an increase in temperature, underscoring the urgent need for enhanced conservation efforts for this beetle species.

Disturbing the lignocellulose digestive system of termites is considered to be a promising approach for termite control. The research on the tolerance mechanism of the termite lignocellulose digestive system to harmful environment conditions is limited. In this study, we keep Coptotermes formosanus Skiraki under a non-lethal toxic condition by feeding the termites with filter paper containing the kojic acid (a low toxic insecticide). The effects of low toxic stress on the activities and gene expressions of host/symbiotic originated lignocellulases, and on the symbiotic microbial community structure of C. formosanus were explored. Our result showed that the low toxic stress would lead to the synchronous decrease of cellulase and hemicellulase activities, and supplementary increase of corresponding gene expressions. The symbiotic community maintained its role as the main force in the lignocellulolytic system of C. formosanus. Meanwhile, a large number of rare taxa were significantly enriched by kojic acid treatment. These numerically inconspicuous bacterial populations might be responsible for the functions similar to phenoloxidase or insecticide detoxification and enable C. formosanus to tolerate the harmful environment. Overall, our data suggested that the digestive adaptation of C. formosanus to physiotoxic feeding is closely related to the triple collaboration of termites–flagellates–bacteria.

Biochar has attracted worldwide attention owing to its potential for mitigating greenhouse gas emissions, improving soil properties, increasing plant growth and so on. While, the assessment of a substantial amount of security is required to determine before biochar is more extensively applied. Our goal was to evaluate the security of biochar by determining the effect of biochar on the preference of soil arthropods for microhabitats. In this study, we examined the effect of varying amounts of biochar on the preference of the Formosan subterranean termite (Coptotermes formosanus) to microhabitats. In addition, we analyzed key soil characteristics to explore their relevance to the termite preferences. Our results found that when compared with 0% (control soil), there was no preference when 2.5% and 5% of biochar were applied. The application of >5% biochar repelled the termites, which then left these soils. Their fresh weight and rates of survival also decreased. The soil pH increased, but the humidity decreased when >5% of biochar was applied. Soil bacteria composition when biochar was amended at 20% also differed from 0% and 2.5% applications. The relative abundance of Cellvibrio and Flavisolibacter in 20% were significantly higher than 0% and 2.5%, while the relative abundance of Burkholderia, Candidatus_Solibacter, Dyella, Edaphobacter, Fulvimonas and Occallatibacter were significantly lower than them. And the functional results predicted by Bugbase suggested that biochar application can cause an increase in the soil potentially pathogen phenotype. In conclusion, our research indicated that biochar can affect the preference of termites for microhabitats and changes in the characteristics of soil might cause changes in these preferences. In addition, our results suggest that soil that has been amended with >10% biochar has the potential to control termites.