Chenxi Liu

Imperata cylindrica is a highly invasive grass that causes severe ecological and agricultural damage worldwide, yet effective and sustainable management options remain limited. In this study, we investigated insects associated with the stems and rhizosphere soil of I. cylindrica in four parks in Beijing, China, and evaluated the utility of DNA barcoding for species identification and natural enemy discovery. A total of 16 insect samples were collected, and the mitochondrial COI gene was amplified using universal (LCO1490/HCO2198) and degenerate (KC-COI-F/R) primers. High-quality sequences were obtained from 12 of the 16 individual specimens, representing two classes (Insecta and Symphyla), two orders (Diptera and Coleoptera), and five families (Chloropidae, Muscidae, Rhiniidae, Eumolpidae, and Scutigerellidae). Chloropidae larvae (Diptera) dominated the stem-associated samples, and Pseudocolaspis sp. (Coleoptera: Eumolpidae), Atherigona orientalis (Diptera: Muscidae), Rhyncomya pruinosa (Diptera: Rhiniidae), and a species of Scutigerellidae (Symphyla) were also identified. BLAST analysis assigned the chloropid sequences to Chloropidae sp. BIOUG02404-H03 with 96.93–97.34% identity, and these sequences were recovered from stems at all four sampling sites. These results demonstrate that DNA barcoding effectively identifies morphologically challenging immature stages and soil-dwelling specimens. The abundant chloropid larvae, which feed internally in I. cylindrica stems, represent a promising candidate for further host-specificity testing as a classical biological control agent. This study provides the first molecular characterization of insects associated with I. cylindrica in Beijing and highlights the value of DNA barcoding in biocontrol resource discovery.

The brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae), is a globally invasive agricultural pest that has rapidly expanded across North America, Europe, and Asia over the past three decades. Understanding the drivers of its invasion success is critical for predicting future spread and informing management. In this study, we assembled a comprehensive mitochondrial COI dataset comprising 1039 sequences from 15 countries across the species' native and introduced ranges, including 119 newly obtained sequences. We identified 65 haplotypes, including eight novel variants, and performed genetic diversity analysis, haplotype network reconstruction, and Mantel tests to quantitatively assess whether patterns of genetic differentiation are consistent with isolation by distance (IBD) or isolation by environment (IBE). Native populations, particularly China and Japan, exhibited high haplotype diversity and pronounced genetic differentiation, suggesting long‐term independent evolution. Introduced populations generally showed reduced diversity consistent with founder effects, with two notable exceptions: Greece and Belgium displayed high haplotype diversity and positive Fu's Fs values, identifying them as potential genetic admixture zones resulting from multiple introductions. The haplotype network revealed two dominant lineages, H1 and H3, with distinct geographic distributions. Mantel tests detected no significant correlations between genetic distance and either geographic distance or climatic dissimilarity ( p > 0.05). While the limited resolution of a single mitochondrial marker precludes definitive conclusions about the absence of IBD/IBE, these findings are consistent with the hypothesis that frequent and large‐scale human‐mediated dispersal may have overwhelmed signals of natural population structure. By quantitatively decoupling genetic structure from biogeographic templates, this study advances our understanding of invasion mechanisms and underscores the need for biosecurity strategies that target human‐mediated dispersal pathways.

Closely related insect species with different feeding habits may exhibit divergent physiological responses to starvation. Here, we compared the predatory Arma chinensis and the phytophagous pest Halyomorpha halys under identical starvation conditions. A. chinensis survived significantly longer than H. halys (females: 39 vs. 9 days; males: 29 vs. 7 days), with slower body weight decline. Starvation severely suppressed reproduction in both species, associated with arrested ovarian development and downregulation of vitellogenin ( Vg ) genes. In carbohydrate, lipid, and amino acid metabolism, A. chinensis showed relatively stable expression of key metabolic genes, while H. halys exhibited transient upregulation followed by rapid attenuation. These results suggest that feeding habits may drive divergence in physiological and molecular responses to starvation. The strong starvation tolerance of A. chinensis may have implications for its use in biological control, while the vulnerability of H. halys to food deprivation could be relevant for pest management strategies.

Phototactic behavior is critical for insect ecological adaptation, especially visual responses to light wavelengths. This study examined locomotor responses to red and ultraviolet (UV) light in congeneric pentatomids, a predator ( Arma chinensis ) versus a pest ( Halyomorpha halys ), and explored the underlying visual molecular mechanisms. Results showed that red and UV light significantly increased total movement distance of both species with distinct species—and sex‐specific differences. Red light exerted the strongest promoting effect on total movement distance, particularly during 4–8 h of exposure. Male A. chinensis traveled farther, moved faster, and paused more frequently than females under red and UV light. Male H. halys moved faster and paused more frequently under red light; H. halys moved faster than A. chinensis under red light, while female H. halys had longer pause duration than female A. chinensis under UV light. For H. halys , females traveled farther under control light, with no sex difference under red light and males traveling farther under UV light. H. halys possesses three long‐wavelength opsins versus two in A. chinensis . Both species share the conserved 7tm_photoreceptors_insect domain and typical GPCR characteristics, and their opsins are highly homologous with other Hemiptera. Although conducted under laboratory conditions, our findings provide valuable insights into the development of environmentally friendly pest control methods and open new avenues for basic and applied insect visual ecology research.

Arma chinensis (Fallou) (a predatory insect) and Halyomorpha halys (Stål) (a phytophagous insect) exhibit distinct feeding ecologies. This contrast provides a model system to investigate metabolic divergence in insects, which remains insufficiently characterized. To address this, we employed untargeted metabolomics for comparing the global metabolic profiles of these 2 species. Significant differences were detected between A. chinensis and H. halys, with 194 and 195 differentially abundant metabolites identified in females and males, respectively. The metabolic profile of A. chinensis was characterized by an enrichment of lipids and lipid-like molecules. In contrast, H. halys exhibited an enrichment of organic acids, their derivatives, and plant-derived secondary metabolites, consistent with its phytophagous diet. Sex-specific metabolic patterns were also observed: females showed higher lipid accumulation, a pattern often associated with reproductive investment in insects, whereas males displayed a relative increase in metabolites related to protein synthesis. This study elucidates the distinct metabolomic signatures associated with different feeding habits for 2 closely related insect species. These findings provide a foundation for further investigation into the physiological correlates of dietary ecology and may inform future research into pest management strategies.

Chitin synthase (CHS) is essential for maintaining exoskeletal integrity and environmental adaptability in insects. CHS genes are categorized into two types, CHS1 and CHS2. Hemipteran insects possess only the CHS1 gene due to the absence of a peritrophic matrix (PM) in their midgut. However, the identification and functional characterization of the CHS1 gene in Pentatomidae species have not been reported. This study reports the first identification of a CHS gene, ArmaCHS1, from the predatory stink bug, Arma chinensis, and investigates its role in response to temperature stress. The ArmaCHS1 open reading frame spans 4407 bp, encoding a protein of 1468 amino acids, with 14 transmembrane helices and seven N-glycosylation sites. Phylogenetic analysis confirmed its classification within the CHS1 clade, closely related to CHS1 from Halyomorpha halys. qRT-PCR analysis revealed that ArmaCHS1 is predominantly expressed in the exoskeleton and displays developmentally regulated expression (lowest in eggs, highest in adults). Temperature stress experiments demonstrated that ArmaCHS1 expression was significantly upregulated at low temperatures (12 °C, 19 °C) and markedly downregulated at high temperatures (33 °C, 40 °C). These findings indicate that ArmaCHS1 likely contributes to thermal adaptation in A. chinensis by modulating chitin biosynthesis, providing new insights into the environmental stress responses of beneficial predatory insects.