Chemical pesticides constitute a core cornerstone of modern agricultural pest control practices. Contemporary management paradigms remain narrowly focused on post-embryonic pest stages, creating critical knowledge gaps in ovicidal intervention strategies that are pivotal for effective source-specific pest population suppression. Locusta migratoria is one of the key pests that pose a serious threat to agricultural production. However, current control measures for this pest are mainly focused on the nymph or adult stages. As a widely deployed thiourea insecticide, diafenthiuron exhibits excellent control efficacy against a variety of polyphagous agricultural pests. Here we systematically investigated the lethal effects of diafenthiuron on L. migratoria eggs and its ovicidal mechanism. Ultrastructural analysis based on transmission electron microscopy and concentration-gradient immersion bioassays targeted at locust eggs clearly demonstrated that the micropyle serves as the primary entry portal for diafenthiuron penetration into the egg interior. Crucially, the compound disrupts the formation of the serosal cuticle, a key chitinous barrier essential for normal insect embryogenesis and egg development. Treated eggs exhibited a statistically significant reductions in cuticle thickness and notable structural disorganization relative to untreated control groups, ultimately inducing distinct concentration-dependent embryonic lethality in target pests. These key findings reveal a previously unrecognized defensive function of the serosal cuticle in blocking xenobiotic infiltration and advance our comprehensive understanding of insect egg protective systems. The dual mechanism of micropyle accessibility and serosal cuticle resistance establishes a practical framework for stage-specific agricultural pest control and provides valuable insights for rationally optimizing ovicidal pesticide development.

The pro-nymphal stage is critical for cuticle formation in the embryonic development of the migratory locust, Locusta migratoria, providing essential protection for embryonic stability and hatching. However, the molecular mechanisms regulating cuticular lamellar assembly during this stage remain largely unknown, especially in hemimetabolous insects. This study focuses on the roles of Knickkopf (LmKnk) and Retroactive (LmRtv) in the formation of the lamellar cuticle in the pro-nymphal stage. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis showed that transcript levels of LmKnk and LmRtv were significantly upregulated during the key cuticle formation period (embryonic day 8 to day 11, E8 to E11). RNA interference-mediated silencing of either gene resulted in a significantly reduced hatching rate, with over half of the individuals dying due to molting failure; disrupted the cuticular ultrastructure, including complete loss of the typical chitin lamellar structure; and impaired the cuticular barrier function, resulting in severely reduced desiccation tolerance. Immunofluorescence localization showed LmRtv is distributed in epidermal cells, suggesting a potential role in facilitating LmKnk trafficking to the procuticle. LmKnk then integrates into the cuticular matrix to ensure ordered chitin assembly. This study is the first to demonstrate the essential role of the LmKnk and LmRtv are essential for embryonic cuticle formation in a hemimetabolous insect, providing mechanistic insights into structural regulation and identifying a potential target for developing cuticle-based pest control strategies.

BACKGROUND:Insect egg stages represent an underexploited developmental phase in pest management. Locusta migratoria, a globally significant agricultural pest, lacks comprehensive defense studies during this vulnerable period, as existing strategies predominantly target later life stages. This study focused on locust eggs to assess the resistance of different protective structures to Metarhizium anisopliae infection. RESULTS:The results show that M. anisopliae infection significantly reduced immune gene expression in eggs while the fungus proliferated with egg development and ultimately caused egg death. The chorion showed no resistance to fungal invasion at the median lethal concentration (LC50) and weak resistance when the fungal concentration was reduced to 0.91 × 107 conidia/mL. Inoculating different parts of locust eggs with M. anisopliae can all lead to the death of locust eggs. Subsequent infection with M. anisopliae after knockdown of LmCHS1, which inhibited serosal cuticle formation, resulted in a significant reduction in egg survival rate. CONCLUSION:This study indicates that M. anisopliae can invade various parts of locust eggs. While the chorion improves protection against low dose fungal infections, the serosal cuticle has a critical role in resisting the invasion of foreign substances. In addition, our results reveal the immunosuppressive effect of M. anisopliae on locust eggs. These results elucidate previously unrecognized egg defense mechanisms in locusts and reveal potential targets for novel management approaches during early development. Such findings stand to advance sustainable pest management by shifting intervention focus to the egg stage, boosting control efficacy and reducing reliance on chemical pesticides. © 2026 Society of Chemical Industry.

The embryonic pro-nymphal cuticle of hemimetabolous insects is a critical protective structure, yet the molecular mechanisms governing its formation, particularly the regulation of chitin organization, remain poorly understood. Chitin deacetylases (CDAs) are key enzymes that modify chitin physicochemical properties, prompting this study to investigate the functions of two Group I CDAs, LmCDA1 and LmCDA2, during the formation of the pro-nymphal cuticle in Locusta migratoria. We found that both LmCDA1 and LmCDA2 were highly expressed during the key period of pro-nymphal cuticle formation (E8-E11). Immunofluorescence localization revealed that LmCDA1 and LmCDA2 proteins were deposited in the apical region of the procuticle. RNA interference (RNAi)-mediated knockdown of LmCDA1 significantly reduced cuticle thickness but did not disrupt the helicoidal organization of chitin laminae. In contrast, knockdown of LmCDA2 completely abolished the laminar structure, resulting in disorganized chitin microfibrils and increased cuticle thickness. Together, these results demonstrate that LmCDA1 and LmCDA2 play distinct and complementary roles in regulating the biosynthesis and structural integrity of the pro-nymphal cuticle. Functional assays further revealed that suppression of either gene impaired the cuticular barrier, accelerated water loss under desiccating conditions, and significantly reduced egg tolerance to dryness. This study provides evidence that CDAs are essential for embryonic cuticle formation and desiccation resistance in a hemimetabolous insect. Our findings offer new insights into the evolutionary functional diversification of CDAs and suggest a potential novel strategy for locust control by targeting chitin metabolism during embryogenesis.

As key members of xenobiotic transcription factors (XFTs), CncC and Maf mediate insecticide sensitivity by regulating detoxification enzyme genes. In this study, with Locusta migratoria as a model, investigations revealed that LmCncC showed particularly high expression in the foregut, midgut, hindgut, and fat bodies. In contrast, LmMaf expression was predominantly localized to the midgut and fat bodies. Functional analysis demonstrated that RNAi-mediated knockdown of LmCncC/LmMaf significantly increased sensitivity to deltamethrin and imidacloprid. To identify the LmCncC- and LmMaf-regulated genes, a comparative transcriptomics analysis was constructed and further identified three key uridine diphosphate-glucuronosyltransferase (UGT) genes downstream of the CncC/Maf pathway. To investigate the role of UGTs in insecticide detoxification, treatment of L. migratoria with sulfinpyrazone, a UGT inhibitor, reduced UGT activity by 42.2% and enhanced sensitivity to imidacloprid and deltamethrin. Among these UGT genes, RNAi-mediated knockdown of LmUGT392C1 significantly enhanced susceptibility to imidacloprid in insecticide bioassays. CRISPR-Cas9-generated LmCncC and LmUGT392C1 mutants validated the essential role of this pathway in imidacloprid detoxification. To clarify the regulatory mechanism of the CncC/Maf signaling pathway on LmUGT392C1, a 2623 bp promoter sequence of LmUGT392C1 was obtained. Dual-luciferase reporter gene assays confirmed that co-overexpression of LmCncC and LmMaf directly activates the promoter of LmUGT392C1. Our study elucidates the CncC/Maf-LmUGT392C1 regulatory axis in insecticide sensitivity, which is applicable to designing new formulations to overcome detoxification or identify potential new resistance mechanisms.

The desert locust (Schistocerca gregaria) represents one of the most destructive agricultural pests globally, renowned for its ability to form massive swarms that can devastate crops and threaten food security across vast regions. Despite the widespread application of the CRISPR/Cas9 gene-editing system in several insect orders, its utilization in locusts, particularly in the desert locust, has remained relatively unexplored. We established a CRISPR/Cas9-mediated gene-editing workflow for the desert locust using gene encoding for neuropeptide corazonin (Crz) as a target. We also analyzed the phenotypic and physiological characteristics of the mutant using paraffin sectioning, HE staining, and chitin staining techniques. Our findings revealed that while Crz knockout desert locusts were viable and maintained normal fertility, they exhibited striking phenotypic alterations, including albinism and a significant reduction in cuticle thickness. These observations not only highlight the functional role of Crz in pigmentation and cuticle development but also underscore the potential of CRISPR/Cas9 as a powerful tool for dissecting gene function in locusts. Furthermore, the successful application of CRISPR/Cas9 in desert locusts also paves the way for similar genetic studies in other non-model insects, expanding the scope of functional genomics in entomology.

Serpins play a crucial role in in various physiological processes of insects. Previous studies have suggested that Serpins regulated processes like egg diapause, melanization, and antimicrobial peptide synthesis in Locusta migratoria, but their overall functional characterization remains insufficient. In this study, the functions of LmSerpin5 in regulating developmental processes and innate immunity were investigated via CRISPR/Cas9-mediated knockout. Homozygous LmSerpin5 mutation caused complete embryonic lethality. By contrast, chimeric mutants showed elevated mortality during embryonic-to-first-instar nymph transition, though chitinous tissue development remained unaffected. Additionally, adult mutants exhibited no external malformations but displayed pathological changes in immune organs, including fat body cells with enlarged lipid droplets and nuclei, and midgut absorptive cells lacking brush borders. Furthermore, pro-nymphal midguts exhibited reduced microvilli density, structural defects, and inflammatory intestinal folds. Molecular analysis confirmed upregulation of Toll pathway downstream genes (LmMyd88, LmPelle and LmTube) in mutant tissues, with midgut-specific activation of LmTube and LmPelle linking structural damage to immune dysregulation. These results demonstrated LmSerpin5 maintains homeostasis through dual mechanisms: ensuring embryonic survival and suppressing excessive Toll activation.

The pro-nymphal cuticle, serving as a protective structure that facilitates environmental adaptation, is critical for insect embryonic development. However, the mechanisms governing its formation remain poorly understood. In this study, we investigated the important role of chitin synthase (LmCHS1) in the formation of the pro-nymphal cuticle during embryonic development in Locusta migratoria. The pro-nymphal cuticle begins to form in 8-day-old embryos (E8) and undergoes degradation by E12, coinciding with the preparatory phase (E13-E14) for hatching of the first-instar nymph. Spatiotemporal expression analysis indicated that LmCHS1 mRNA levels are elevated before cuticle formation, with protein localization peaking at the plasma membrane during active chitin synthesis (E8-E11). Targeting LmCHS1 through embryonic RNA interference (RNAi) resulted in developmental failures during late embryogenesis. Additionally, ultrastructural analysis confirmed that silencing LmCHS1 disrupts the normal chitin structure in the pro-nymphal cuticle. Further investigation into the ecological function of LmCHS1 in adapting the pro-nymphal cuticle to dry environments revealed that the tolerance of embryo to various dry conditions is significantly reduced after konckdown of LmCHS1. In summary, these findings highlight the essential role of chitin synthase in the formation of the pro-nymphal cuticle in locust embryos, underscoring its importance in embryonic development and adaptation to environmental challenges like desiccation.

This study evaluated tyrosinase inhibition by peptides from locust (Locusta migratoria) protein using enzymatic hydrolysis and ultrafiltration. Peptides with molecular weights below 1 kDa exhibited the strongest inhibitory effect, with a 53.00 ± 0.65 % inhibition rate at 10 mg/mL. Structural analysis revealed that peptides with exposed aromatic amino acids and low α-helix content exhibited enhanced inhibitory activity. LC-MS/MS identified 1108 sequences, mainly from Vitellogenin B and A. Kinetic studies confirmed that the peptides act as mixed-type, reversible inhibitors. Molecular docking identified key interactions, including hydrogen bonds and hydrophobic interactions with critical residues in the enzyme's active site, preventing substrate binding. The peptides exhibited low cytotoxicity in HEK-293 T cells and showed a 37.26 % inhibition rate of tyrosinase in B16 melanoma cells at 2 mg/mL. These findings highlight the potential of locust peptides as effective and safe tyrosinase inhibitors. They could have important applications in cosmetics, pigmentation treatments, and food preservation.

Ma2 and Ma3 hydrocarbon source rock samples from the Fengcheng Formation in well Maye 1, Mahu Depression, Junggar Basin, were studied using conventional geochemical analysis methods and saturated hydrocarbon gas chromatography–mass spectrometry. The distribution patterns, abundance, relative content, and ratios of different carbon compounds of tricyclic terpane in hydrocarbon source rocks from fresh-to-mildly-saline (type I), moderately saline (type II), and saline (type III) water environments significantly differed. The C28–C29TT/C30H and C19–C29TT/C30H ratios were the lowest in the type I hydrocarbon source rock. The relative ratios of C23TT/C21TT, C25TT/C24TT, C28TT/C26TT, (C23–C26TT)/(C19–C22TT), and (C28–C29TT)/(C19–C22TT) gradually increased with the increase in the salinity of the hydrocarbon source rock. The percentage of low-carbon tricyclic terpanes gradually decreased to 28%, whereas those of the medium- and high-carbon tricyclic terpanes increased to 52% and 20%, respectively. The differences in triterpane types of different hydrocarbon source rocks were mainly controlled by the depositional environment. The primary factor that controlled the distribution pattern; relative abundance, especially the high carbon tricyclic terpane content; and differences in the relative ratio of different carbon compounds in different hydrocarbon source rocks was the salinity of the ancient waterbody during deposition.

7-dehydrocholesterol (7-DHC) is a key intermediate product used for biosynthesis of molting hormone. This is achieved through a series of hydroxylation reactions catalyzed by the Halloween family of cytochrome P450s. Neverland is an enzyme catalyzes the first reaction of the ecdysteroidogenic pathway, which converts dietary cholesterol into 7-DHC. However, research on the physiological function of neverland in orthopteran insects is lacking. In this study, neverland from Locusta migratoria (LmNvd) was cloned and analyzed. LmNvd was mainly expressed in the prothoracic gland and highly expressed on days 6 and 7 of fifth instar nymphs. RNAi-mediated silencing of LmNvd resulted in serious molting delays and abnormal phenotypes, which could be rescued by 7-DHC and 20-hydroxyecdysone supplementation. Hematoxylin and eosin staining results showed that RNAi-mediated silencing of LmNvd disturbed the molting process by both promoting the synthesis of new cuticle and suppressing the degradation of the old cuticle. Quantitative real-time PCR results suggested that the mRNA expression of E75 early gene and chitinase 5 gene decreased and that of chitin synthase 1 gene was markedly upregulated after knockdown of LmNvd. Our results suggest that LmNvd participates in the biosynthesis process of molting hormone, which is involved in regulating chitin synthesis and degradation in molting cycles.

Group I chitin deacetylases (CDAs), CDA1 and CDA2, play an essential role in cuticle formation and molting in the process of insect wing development. A recent report showed that trachea are able to take up a secreted CDA1 (serpentine, serp) produced in the fat body to support normal tracheal development in the fruit fly Drosophila melanogaster. However, whether CDAs in wing tissue were produced locally or derived from the fat body remains an open question. To address this question, we applied tissue-specific RNAi against DmCDA1 (serpentine, serp) and DmCDA2 (vermiform, verm) in the fat body or the wing and analyzed the resulting phenotypes. We found that repression of serp and verm in the fat body had no effect on wing morphogenesis. RT-qPCR showed that RNAi against serp or verm in the fat body autonomously reduced their expression levels of serp or verm in the fat body but had no non-autonomous effect on the expression in wings. Furthermore, we showed that inhibition of serp or verm in the developing wing caused wing morphology and permeability deficiency. Taken together, the production of Serp and Verm in the wing was autonomous and independent of the fat body.

The Tarim Basin, a significant region of coal-derived gas generation in China, has widely dispersed coal measure source rocks, especially in the Kuqa Depression. The typical coal measure strata from the Kuqa River and Kapushaliang River sections in the Kuqa Depression were systematically sampled. According to a conventional geochemical analysis (including materials and lithology), a total of 25 typical coal measure source rock samples were chosen for chromatography and chromatography–mass spectrometry examination. It was demonstrated that there were significant discrepancies in the coal source rock samples, particularly the coal rock from the Kuqa River section and the Kapushaliang River section. The specific performance of the Kuqa River section was characterized by a high Pr/Ph ratio (up to 9.29), a low gammacerane ratio, a low abundance of tricyclic terpane, and an “L”-type distribution of regular steranes, all of which are consistent with the properties of humic coal found in freshwater lakes that have undergone partial oxidation. The Kapushaliang River section, by contrast, exhibited a low Pr/Ph ratio (<1.0), a high gammacerane ratio, a concentration of tricyclic terpane comparable to that of hopane, and a distribution of regular steranes in a “V” shape, all of which indicate a strongly reduced saline water environment. Additionally, the degree of thermal evolution is not the key factor resulting in the above biomarker diversity within the CSRs, which was supported by the poor correlation between the maturity parameters (Ro%, Tmax °C), the sedimentary environment-related parameters (such as Pr/Ph and Ga/C31H), and the biogenic-related parameters (such as ∑tricyclic terpane/∑ hopane and ∑sterane/∑hopane). A comparative analysis suggested that transgression-related changes in the redox conditions and parent materials triggered the biomarker diversity within the CSRs, resulting in a large difference in the hydrocarbon-forming parent materials between the two abovementioned outcrop sections. These might provide some insight for hydrocarbon exploration from CSRs, which have been attracting increasing attention in China, with proven coal reserves are ranked first in the world.

The Songliao Basin is one of the largest continental oil and gas basins in China;the Lishu Fault Depression is a secondary tectonic unit of the Songliao Basin.In this study,71 lacustrine Lishu Fault oil samples were analyzed for saturated hydrocarbons and aromatics.The different compositions indicated by the gas chromatography and gas chromatography-mass spectrometry （GC-MS） data indicated three types of crude oil from the Lishu Fault,each with quite different distributions of tricyclic terpanes.The absolute concentration of tricyclic terpanes in type I oil is obviously higher than in type II;however,theΣtricyclic terpanes/17α（H）-hopanes ratio in type I crude oil is significantly higher than in type II,but it is enriched in high carbon-number tricyclic terpane (C 28 TT-C 29 TT) compounds,with higher relative percentages than in low carbon tricyclic terpenes (C 19 TT-C 20 TT,C 21 TT,C 23 TT).The main influences affecting high carbon number C 28 TT-C 29 TT in the Lishu Fault crude oil are discussed from three aspects:deposition environment,organic matter source,and maturity of the crude oils.It was found that,in the organic matter sources of the different genetic types of crude oil （mainly bacteria and low-grade aquatic organisms）,the (C 28 TT-C 29 TT)/17α（H）-hopanes ratio is positively correlated with the gammacerane index,indicating that a more reductant salt water environment is another factor affecting the enrichment of tricyclic terpane with high carbon number.In the study area,theΣtricyclic terpanes/17α（H）-hopanes ratio is positively correlated with thermal maturity,indicating that a high degree of thermal evolution of the crude oil is more conducive to enrichment in high carbon number tricyclic terpanes.It follows that thermal maturity is the main influence on the different relative abundances of high-carbon tricyclic terpenes in the Lishu Fault Depression.

准噶尔盆地具有丰富的油砂资源,风城油砂矿区所在的西北缘是准噶尔盆地最主要的油砂分布区.对研究区油砂样品抽提物进行饱和烃和芳烃的色质研究中发现,油砂样品中正构烷烃、常规甾烷、单芳甾烷和短链三芳甾烷、重排甾烷均已检测不到,而藿烷类化合物、孕甾烷、升孕甾烷、长链三芳甾烷也仅有少量分布;三环萜烷以及25-降藿烷却异常丰富,揭示该地区原油曾遭受比较严重的生物降解,降解等级在8级以上.就三环萜烷整体碳数分布而言,随着生物降解作用的增强,三环萜烷化合物的抗降解能力会随着碳数的增加而减弱,即三环萜烷(TT)抗生物降解能力为高碳数(C28-C31TT)

Aromatic compounds are important organic components in source rocks and crude oil, which are rich in geochemical information, and they has been wild used in the study of sedimentary environment and maturity, while the influence of sedimentary environment on the distribution characteristics of humic coal aromatic compounds is rare studied.There are obvious differences in aromatic compound content and distribution characteristics of the humic coal samples from the Kuqa River profile of the Kuqa depression and the Kapushaliang River profile in this study.The Kuqa River profile contains high-abundance naphthalene, phenanthrene series compounds and high content of diabenzofuran and alkay diabenzofuran, rich in retene, cadalene, 1,2,5-TMN and 1,2,5,6-TeMN and other higher plant source compounds, which belong to the characteristics of typical oxidation environment swamp phase humic coal.Different from the aromatic distribution of traditional humic coal, the mass spectrometry-chromatography results of humic coal in the Kapushaliang River profile show that it had higher content of phenanthrene series, 9-methylphenanthrene, diabenzothiophene, alkay diabenzothiophene and other compounds that characterized the reduced environment and the input of homonemeae.The research results show that the difference may be due to the biological transformation of higher plants dominated by bacteria and other microorganisms caused by seawater intrusion during the sedimentary diagenesis of the Kapusaliang River section.

Nuclear receptors (NRs) function as key factors in diverse signaling and metabolic pathways. Previous studies have focused on the roles of a nuclear receptor, hormone receptor 4 (HR4), mainly in holometabolous insects, while current knowledge of its function in hemimetabolous insects is still limited. In this study, we identified a HR4 gene in the orthopteran species Locusta migratoria. The full-length open reading frame of LmHR4 comprises 2694-nucleotides encoding a polypeptide of 897 amino acids, which contained a DNA-binding and a ligandbinding domain. Analyzing LmHR4 expression by quantitative reverse-transcription PCR (RT-qPCR) revealed that LmHR4 was highly expressed in integument, hindgut and fat body. During development from 3rd and 5th nymphal instars, the expression of LmHR4 reached maximal levels before ecdysis. We further demonstrated that LmHR4 expression is induced by 20-hydroxyecdysone (20E) and suppressed by silencing LmEcR, suggesting that LmHR4 expression is controlled by 20E signaling. The dsLmHR4-injected nymphs failed to molt and remained in the nymphal stage until death. Hematoxylin and eosin staining of the integument indicated that apolysis in the dsLmHR4-injected insects was delayed compared to that in control insects. Chitin staining and ultra-structural analysis showed that both the synthesis of the new cuticle and the degradation of the old cuticle were blocked in dsLmHR4-injected insects. Silencing LmHR4 decreased 20E titer and down-regulated the transcript levels of genes involved in chitin synthesis and degradation. Taken together, these results suggest that LmHR4 is essential for the formation of epidermal cuticle by mediating the 20E signaling to regulate the expression of chitin synthesis and degradation genes.

The success of the degradation of the extraembryonic serosal cuticle and the second embryonic cuticle (pro-nymphal cuticle) is essential for the development and molting of nymph from egg in Orthoptera Locusta migratoria. Chitinase 5 is an important gene for chitin degradation in nymphs and in the egg stage. In this study, we investigated the important roles of chitinase 5-1 (LmCht5-1) and chitinase 5-2 (LmCht5-2) in the degradation of the serosal and pro-nymphal cuticles during locust embryonic development. The serosal cuticle degrades from 7-day-old embryos (E7) to E13, along with the degradation of the pro-nymphal cuticle, which begins at E12 to E14. The mRNA and protein of LmCht5-1 and LmCht5-2 are expressed during the degradation process of the serosal cuticle and the pro-nymphal cuticle. RNAi experiments at the embryonic stage show that both dsLmCht5-1 and dsLmCht5-2 contribute to the failure of development in early and late embryogenesis. Further, during the serosal cuticle molting process, ultra-structure analysis indicated that dsLmCht5-1 prevented the loss of the coarse chitin layer in the upper part in both early and late embryogenesis. Meanwhile, dsLmCht5-2 blocked the degradation of the lower fine chitin layer at the early stage and blocked the chitin degradation of loose coarse chitin in the late molting process. During the degradation of the pro-nymphal cuticle, dsLmCht5-1 suppresses chitin degradation between layers in the procuticle, while dsLmCht5-2 suppresses chitin degradation into filaments inside of the layer. In summary, our results suggest that both LmCht5-1 and LmCht5-2 contribute to the degradation of the serosal and pro-nymphal cuticles during the locust embryonic stage.