Neofunctionalization of a second insulin receptor gene in the wing-dimorphic planthopper, Nilaparvata lugens.

A single insulin receptor (InR) gene has been identified and extensively studied in model species ranging from nematodes to mice. However, most insects possess additional copies of InR, yet the functional significance, if any, of alternate InRs is unknown. Here, we used the wing-dimorphic brown planthopper (BPH) as a model system to query the role of a second InR copy in insects. NlInR2 resembled the BPH InR homologue (NlInR1) in terms of nymph development and reproduction, but revealed distinct regulatory roles in fuel metabolism, lifespan, and starvation tolerance. Unlike a lethal phenotype derived from NlInR1 null, homozygous NlInR2 null mutants were viable and accelerated DNA replication and cell proliferation in wing cells, thus redirecting short-winged-destined BPHs to develop into long-winged morphs. Additionally, the proper expression of NlInR2 was needed to maintain symmetric vein patterning in wings. Our findings provide the first direct evidence for the regulatory complexity of the two InR paralogues in insects, implying the functionally independent evolution of multiple InRs in invertebrates.

Vestigial mediates the effect of insulin signaling pathway on wing-morph switching in planthoppers.

Wing polymorphism is an evolutionary feature found in a wide variety of insects, which offers a model system for studying the evolutionary significance of dispersal. In the wing-dimorphic planthopper Nilaparvata lugens, the insulin/insulin-like growth factor signaling (IIS) pathway acts as a 'master signal' that directs the development of either long-winged (LW) or short-winged (SW) morphs via regulation of the activity of Forkhead transcription factor subgroup O (NlFoxO). However, downstream effectors of the IIS-FoxO signaling cascade that mediate alternative wing morphs are unclear. Here we found that vestigial (Nlvg), a key wing-patterning gene, is selectively and temporally regulated by the IIS-FoxO signaling cascade during the wing-morph decision stage (fifth-instar stage). RNA interference (RNAi)-mediated silencing of Nlfoxo increase Nlvg expression in the fifth-instar stage (the last nymphal stage), thereby inducing LW development. Conversely, silencing of Nlvg can antagonize the effects of IIS activity on LW development, redirecting wing commitment from LW to the morph with intermediate wing size. In vitro and in vivo binding assays indicated that NlFoxO protein may suppress Nlvg expression by directly binding to the first intron region of the Nlvg locus. Our findings provide a first glimpse of the link connecting the IIS pathway to the wing-patterning network on the developmental plasticity of wings in insects, and help us understanding how phenotypic diversity is generated by the modification of a common set of pattern elements.

Abdominal-B contributes to abdominal identity in the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae).

The homeotic complex gene Abdominal-B (Abd-B) is involved in regulating the development of posterior abdomens and has been extensively studied in holometabolous insects. However, the function of Abd-B in hemimetabolous insects is not fully understood. Here, we functionally characterize an Abd-B homologue in the brown planthopper (BPH), Nilaparvata lugens. The full-length cDNA of the N. lugens Abd-B homologue (NlAbd-B) is 2334 nt, with an open reading frame of 1113 bp. NlAbd-B has the highest expression level at the egg stage relative to the nymphal and adult stages and is mainly expressed in the fourth to the ninth abdominal segment of embryos. RNA interference (RNAi)-mediated knockdown of NlAbd-B in nymphs disrupted the development of genitalia both in females and males and caused a genitalia-to-leg transformation. Parental RNAi of NlAbd-B in both female and male adults caused an extra abdominal segment in offspring nymphs, while parental RNAi of the N. lugens abdominal-A homologue in both female and males adults led to embryos with leg-like appendages on the second to the eighth abdominal segment. These findings suggest that NlAbd-B plays a pivotal role in genital development and posterior abdominal patterning and thus highlight the conservational role of Abd-B in holometabolous and hemimetabolous insects.

Using a machine learning approach to identify key prognostic molecules for esophageal squamous cell carcinoma.

BACKGROUND: A plethora of prognostic biomarkers for esophageal squamous cell carcinoma (ESCC) that have hitherto been reported are challenged with low reproducibility due to high molecular heterogeneity of ESCC. The purpose of this study was to identify the optimal biomarkers for ESCC using machine learning algorithms. METHODS: Biomarkers related to clinical survival, recurrence or therapeutic response of patients with ESCC were determined through literature database searching. Forty-eight biomarkers linked to recurrence or prognosis of ESCC were used to construct a molecular interaction network based on NetBox and then to identify the functional modules. Publicably available mRNA transcriptome data of ESCC downloaded from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets included GSE53625 and TCGA-ESCC. Five machine learning algorithms, including logical regression (LR), support vector machine (SVM), artificial neural network (ANN), random forest (RF) and XGBoost, were used to develop classifiers for prognostic classification for feature selection. The area under ROC curve (AUC) was used to evaluate the performance of the prognostic classifiers. The importances of identified molecules were ranked by their occurrence frequencies in the prognostic classifiers. Kaplan-Meier survival analysis and log-rank test were performed to determine the statistical significance of overall survival. RESULTS: A total of 48 clinically proven molecules associated with ESCC progression were used to construct a molecular interaction network with 3 functional modules comprising 17 component molecules. The 131,071 prognostic classifiers using these 17 molecules were built for each machine learning algorithm. Using the occurrence frequencies in the prognostic classifiers with AUCs greater than the mean value of all 131,071 AUCs to rank importances of these 17 molecules, stratifin encoded by SFN was identified as the optimal prognostic biomarker for ESCC, whose performance was further validated in another 2 independent cohorts. CONCLUSION: The occurrence frequencies across various feature selection approaches reflect the degree of clinical importance and stratifin is an optimal prognostic biomarker for ESCC.

Two insulin receptors determine alternative wing morphs in planthoppers.

Wing polyphenism is an evolutionarily successful feature found in a wide range of insects. Long-winged morphs can fly, which allows them to escape adverse habitats and track changing resources, whereas short-winged morphs are flightless, but usually possess higher fecundity than the winged morphs. Studies on aphids, crickets and planthoppers have revealed that alternative wing morphs develop in response to various environmental cues, and that the response to these cues may be mediated by developmental hormones, although research in this area has yielded equivocal and conflicting results about exactly which hormones are involved. As it stands, the molecular mechanism underlying wing morph determination in insects has remained elusive. Here we show that two insulin receptors in the migratory brown planthopper Nilaparvata lugens, InR1 and InR2, have opposing roles in controlling long wing versus short wing development by regulating the activity of the forkhead transcription factor Foxo. InR1, acting via the phosphatidylinositol-3-OH kinase (PI(3)K)-protein kinase B (Akt) signalling cascade, leads to the long-winged morph if active and the short-winged morph if inactive. InR2, by contrast, functions as a negative regulator of the InR1-PI(3)K-Akt pathway: suppression of InR2 results in development of the long-winged morph. The brain-secreted ligand Ilp3 triggers development of long-winged morphs. Our findings provide the first evidence of a molecular basis for the regulation of wing polyphenism in insects, and they are also the first demonstration--to our knowledge--of binary control over alternative developmental outcomes, and thus deepen our understanding of the development and evolution of phenotypic plasticity.

A genome-wide identification and analysis of the homeobox genes in the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae).

The homeobox family is a large and diverse superclass of genes, many of which act as transcription factors that play important roles in tissue differentiation and embryogenesis in animals. The brown planthopper (BPH), Nilaparvata lugens, is the most destructive pest of rice in Asia, and high fecundity contributes significantly to its ecological success in natural and agricultural habits. Here, we identified 94 homeobox genes in BPH, which could be divided into 75 gene families and 9 classes. This number is comparable to the number of homeobox genes found in the honeybee Apis mellifera, but is slightly less than in Drosophila or the red flour beetle Tribolium castaneum. A spatio-temporal analysis indicated that most BPH homeobox genes were expressed in a development and tissue-specific manner, of which 21 genes were highly expressed in ovaries. RNA interference (RNAi)-mediated functional assay showed that 22 homeobox genes were important for nymph development and the nymph to adult transition, whereas 67 genes were dispensable during this process. Fecundity assay showed that knockdown of 13 ovary-biased genes (zfh1, schlank, abd-A, Lim3_2, Lmxb, Prop, ap_1, Not, lab, Hmx, vis, Pknox, and C15) led to the reproductive defect. This is the first comprehensive investigation into homeobox genes in a hemipteran insect and thus helps us to understand the functional significance of homeobox genes in insect reproduction.

Crocin Alleviates Pain Hyperalgesia in AIA Rats by Inhibiting the Spinal Wnt5a/ß-Catenin Signaling Pathway and Glial Activation.

At present, most of the drugs have little effect on the pathological process of rheumatoid arthritis (RA). Analgesia is an important measure in the treatment of RA and is also one of the criteria to determine the therapeutic effects of the disease. Some studies have found that crocin, a kind of Chinese medicine, can effectively alleviate pain sensitization in pain model rats, but the mechanism is not clear. Emerging evidence indicates that crocin may inhibit the metastasis of lung and liver cancer cells from the breast by inhibiting Wnt/ß-catenin and the Wnt signaling pathway is closely related to RA. Wnt5a belongs to the Wnt protein family and was previously thought to be involved only in nonclassical Wnt signaling pathways. Recent studies have shown that Wnt5a has both stimulatory and inhibitory effects on the classical Wnt signaling pathway, and so, Wnt5a has attracted increasing attention. This study demonstrated that crocin significantly increased the mechanical thresholds of adjuvant-induced arthritis (AIA) rats, suggesting that crocin can alleviate neuropathic pain. Crocin significantly decreased the levels of pain-related factors and glial activation. Foxy5, activator of Wnt5a, inhibited the above effects of crocin in AIA rats. In addition, intrathecal injection of a Wnt5a inhibitor significantly decreased hyperalgesia in AIA rats. This research shows that crocin may alleviate neuropathic pain in AIA rats by inhibiting the expression of pain-related molecules through the Wnt5a/ß-catenin pathway, elucidating the mechanism by which crocin relieves neuropathic pain and provides a new way of thinking for the treatment of AIA pain.

Molecular Mechanisms of Wing Polymorphism in Insects.

Many insects are capable of developing into either long-winged or short-winged (or wingless) morphs, which enables them to rapidly match heterogeneous environments. Thus, the wing polymorphism is an adaptation at the root of their ecological success. Wing polymorphism is orchestrated at various levels, starting with the insect's perception of environmental cues, then signal transduction and signal execution, and ultimately the transmitting of signals into physiological adaption in accordance with the particular morph produced. Juvenile hormone and ecdysteroid pathways have long been proposed to regulate wing polymorphism in insects, but rigorous experimental evidence is lacking. The breakthrough findings of ecdysone receptor regulation on transgenerational wing dimorphism in the aphid Acyrthosiphon pisum and of insulin signaling in the planthopper Nilaparvata lugens greatly broaden our understanding of wing polymorphism at the molecular level. Recently, the advent of high-throughput sequencing coupled with functional genomics provides powerful genetic tools for future insights into the molecular bases underlying wing polymorphism in insects.

Mesenchymal stem cell transplantation carried in SVVYGLR modified self-assembling peptide promoted cardiac repair and angiogenesis after myocardial infarction.

The efficiency of stem cell therapy for myocardial infarction (MI) was very low due to the hostile microenvironment and poor blood perfusion. In this study, we designed a new self-assembling peptide through adding angiogenic polypeptide SVVYGLR to the carboxyl terminal of RADA16, and evaluated the therapeutic potential of mesenchymal stem cell (MSC) transplantation carried in this designer self-assembling peptide (DSP) on MI. After the model of cell ischemia and hypoxia was established in vitro, cytoprotective effect of DSP on MSC was detected by AO/EB staining. MI was induced by ligating of the left anterior descending artery in female SD rats. MSC from male rats was labled by GFP with adenovirus transfection. MSC with DSP (MSC-DSP) or without DSP (MSC) were transplanted at the border of the infarcted area. The number of survival cell was more and necrotic cell was less in DSP group than that in control group after ischemia and hypoxia treatment in vitro. At 4 weeks after cell transplantation, compared with the MSC group, improvement of cardiac function was better, infarct size was reduced, collagen content and the number of apoptotic cells was decreased, and there were more GFP or SRY positive cells in MSC-DSP group. Moreover, the number of CD31 or α-smooth muscle actin positive blood vessels in MSC-DSP group was significantly higher than that in MSC group. DSP not only provided a microenvironment for the survival of MSC, but also promoted the angiogenesis after transplantation. This study provided novel strategy and experimental evidence for the clinical application of biomaterials in stem cell transplantation for treatment of ischemic heart disease such as MI.

Comparative analysis of the transcriptional responses to low and high temperatures in three rice planthopper species.

The brown planthopper (Nilaparvata lugens, BPH), white-backed planthopper (Sogatella furcifera, WBPH) and small brown planthopper (Laodelphax striatellus, SBPH) are important rice pests in Asia. These three species differ in thermal tolerance and exhibit quite different migration and overwintering strategies. To understand the underlying mechanisms, we sequenced and compared the transcriptome of the three species under different temperature treatments. We found that metabolism-, exoskeleton- and chemosensory-related genes were modulated. In high temperature (37 °C), heat shock protein (HSP) genes were the most co-regulated; other genes related with fatty acid metabolism, amino acid metabolism and transportation were also differentially expressed. In low temperature (5 °C), the differences in gene expression of the genes for fatty acid synthesis, transport proteins and cytochrome P450 might explain why SBPH can overwinter in high latitudes, while BPH and WBPH cannot. In addition, other genes related with moulting, and membrane lipid composition might also play roles in resistance to low and high temperatures. Our study illustrates the common responses and different tolerance mechanisms of three rice planthoppers in coping with temperature change, and provides a potential strategy for pest management.

Excited State N-H Tautomer Selectivity in the Singlet Energy Transfer of a Zinc(II)-Porphyrin-Truxene-Corrole Assembly.

An original corrole-containing polyad for S1 energy transfer, in which one zinc(II)-porphyrin donor is linked to two free-base corrole acceptors by a truxene linker, is reported. This polyad exhibits a rapid zinc(II)-porphyrin*→free-base corrole transfer (4.83×1010  s-1 ; 298 K), even faster than the tautomerization in the excited state processes taking advantage of the good electronic communication provided by the truxene bridge. Importantly, the energy transfer process shows approximately 3-fold selectivity for one corrole N-H tautomer over the other even at low temperature (77 K). This selectivity is due to the difference in the J-integral being effective in both the Förster and Dexter mechanisms. The data are rationalized by DFT computations.

Brown planthopper nudivirus DNA integrated in its host genome.

UNLABELLED: The brown planthopper (BPH), Nilaparvata lugens (Hemiptera:Delphacidae), is one of the most destructive insect pests of rice crops in Asia. Nudivirus-like sequences were identified during the whole-genome sequencing of BPH. PCR examination showed that the virus sequences were present in all of the 22 BPH populations collected from East, Southeast, and South Asia. Thirty-two of the 33 nudivirus core genes were identified, including 20 homologues of baculovirus core genes. In addition, several gene clusters that were arranged collinearly with those of other nudiviruses were found in the partial virus genome. In a phylogenetic tree constructed using the supermatrix method, the original virus was grouped with other nudiviruses and was closely related to polydnavirus. Taken together, these data indicated that the virus sequences belong to a new member of the family Nudiviridae. More specifically, the virus sequences were integrated into the chromosome of its insect host during coevolution. This study is the first report of a large double-stranded circular DNA virus genome in a sap-sucking hemipteran insect. IMPORTANCE: This is the first report of a large double-stranded DNA virus integrated genome in the planthopper, a plant sap-sucking hemipteran insect. It is an exciting addition to the evolutionary story of bracoviruses (polydnaviruses), nudiviruses, and baculoviruses. The results on the virus sequences integrated in the chromosomes of its insect host also represent a story of successful coevolution of an invertebrate virus and a plant sap-sucking insect.

Si/ZnO nanocomb arrays decorated with Ag nanoparticles for highly efficient surface-enhanced Raman scattering.

High-density ZnO nanocombs were first grown on a nanoporous silicon pillar array, and pre-prepared 3D Si/ZnO/Ag nanocomb arrays were employed as substrates for surface-enhanced Raman scattering (SERS). The finite-difference time-domain simulation result shows that two kinds of inter-Ag-NP nanogaps in the geometry create a large number of SERS "hot spots," which contributes to the detection limits for rhodamine-6G as low as 10⁻¹² M and the Raman enhancement factor as large as 109. The linear dependence between the Raman peak intensities and the concentrations of thiram provides a new calibration method for rapid and quantitative detection of trace organic molecules.

Salivary proteins NlSP5 and NlSP7 are required for optimal feeding and fitness of the brown planthopper, Nilaparvata lugens.

BACKGROUND: Saliva has a crucial role in determining the compatibility between piercing-sucking insects and their hosts. The brown planthopper (BPH) Nilaparvata lugens, a notorious pest of rice in East and Southeast Asia, secretes gelling and watery saliva when feeding on rice sap. Nlsalivap-5 (NlSP5) and Nlsalivap-7 (NlSP7) were identified as potential planthopper-specific gelling saliva components, but their biological functions remain unknown. RESULTS: Here, we showed by transcriptomic analyses that NlSP5 and NlSP7 were biasedly expressed in the salivary glands of BPHs. Using the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated genome-editing system, we constructed NlSP5 and NlSP7 homozygous mutants (NlSP5-/- and NlSP7-/-). Electrical penetration graph assay showed that NlSP5-/- and NlSP7-/- mutants exhibited abnormal probing and feeding behaviors. Bioassays revealed that the loss-of-function of NlSP5 and NlSP7 significantly reduced the fitness of BPHs, with extended developmental duration, shortened lifespan, reduced weight, and impaired fecundity and hatching rates. CONCLUSION: These findings deepen our understanding of the BPH-host interaction and may provide potential targets for the management of rice planthoppers. © 2024 Society of Chemical Industry.

Small molecular donor materials based on ß-ß-bridged BODIPY dimers with a triphenylamine or carbazole unit for efficient organic solar cells.

Herein, we have designed and synthesized two novel BODIPY dimer-based small molecules, denoted as ZMH-1 and ZMH-2, covalently linked and functionalized with triphenylamine (TPA) (ZMH-1) and carbazole (CZ) (ZMH-2) units as the electron donor at the 3- and 5-positions of the BODIPY core, respectively. Their optical and electrochemical properties were investigated. We have fabricated all small molecule bulk heterojunction organic solar cells using these BODIPY-based small molecules as electron donors along with fullerene derivative (PC71BM) and medium bandgap non-fullerene acceptor IDT-TC as electron acceptors. The optimized OSCs based on ZMH-1:PC71BM, ZMH-2:PC71BM, ZMH-1:IDT-IC, and ZMH-2:IDT-IC attain overall PCEs of 8.91%, 6.61%, 11.28%, and 5.48%, respectively. Moreover, when a small amount of PC71BM as guest acceptor is added to the binary host ZMH-1:IDT-TC and ZMH-2:IDT-TC, the ternary OSCs based on ZMH-1 and ZMH-2 reach PCEs of 13.70% and 12.71%, respectively.

Chromosome-level genome assembly of the bethylid ectoparasitoid wasp Sclerodermus sp. 'alternatusi'.

The Bethylidae are the most diverse of Hymenoptera chrysidoid families. As external parasitoids, the bethylids have been widely adopted as biocontrol agents to control insect pests worldwide. Thus far, the genomic information of the family Bethylidae has not been reported yet. In this study, we crystallized into a high-quality chromosome-level genome of ant-like bethylid wasps Sclerodermus sp. 'alternatusi' (Hymenoptera: Bethylidae) using PacBio sequencing as well as Hi-C technology. The assembled S. alternatusi genome was 162.30 Mb in size with a contig N50 size of 3.83 Mb and scaffold N50 size of 11.10 Mb. Totally, 92.85% assembled sequences anchored to 15 pseudo-chromosomes. A total of 10,204 protein-coding genes were annotated, and 23.01 Mb repetitive sequences occupying 14.17% of genome were pinpointed. The BUSCO results showed that 97.9% of the complete core Insecta genes were identified in the genome, while 97.1% in the gene sets. The high-quality genome of S. alternatusi will not only provide valuable genomic information, but also show insights into parasitoid wasp evolution and bio-control application in future studies.

Cell-specific and pH-activatable rubyrin-loaded nanoparticles for highly selective near-infrared photodynamic therapy against cancer.

Spatiotemporal control of singlet oxygen ((1)O2) release is a major challenge for photodynamic therapy (PDT) against cancer with high therapeutic efficacy and minimum side effects. Here a selenium-rubyrin (NMe2Se4N2)-loaded nanoparticle functionalized with folate (FA) was designed and synthesized as an acidic pH-activatable targeted photosensitizer. The nanoparticles could specifically recognize cancer cells via the FA-FA receptor binding and were selectively taken up by cancer cells via receptor-mediated endocytosis to enter lysosomes, in which NMe2Se4N2 was activated to produce (1)O2. The pH-controllable release of (1)O2 specially damaged the lysosomes and thus killed cancer cells in a lysosome-associated pathway. The introduction of selenium into the rubyrin core enhanced the (1)O2 generation efficiency due to the heavy atom effect, and the substitution of dimethylaminophenyl moiety at meso-position led to the pH-controllable activation of NMe2Se4N2. Under near-infrared (NIR) irradiation, NMe2Se4N2 possessed high singlet oxygen quantum yield (ΦΔ) at an acidic pH (ΦΔ = 0.69 at pH 5.0 at 635 nm) and could be deactivated at physiological pH (ΦΔ = 0.06 at pH 7.4 at 635 nm). The subcellular location-confined pH-activatable photosensitization at NIR region and the cancer cell-targeting feature led to excellent capability to selectively kill cancer cells and prevent the damage to normal cells, which greatly lowered the side effects. Through intravenous injection of FA-NMe2Se4N2 nanoparticles in tumor-bearing mice, tumor elimination was observed after NIR irradiation. This work presents a new paradigm for specific PDT against cancer and provides a new avenue for preparation of highly efficient photosensitizers.

Ag@SiO2 core-shell nanoparticles on silicon nanowire arrays as ultrasensitive and ultrastable substrates for surface-enhanced Raman scattering.

Ag nanoparticles (NPs) coated with silica nanolayers were decorated onto a large-scale and uniform silicon nanowire array (SiNWA) by simple chemical etching and metal reduction processes. The three-dimensional Ag/SiNWAs thus formed are employed as a substrate for surface-enhanced Raman scattering (SERS), and a detection limit for rhodamine 6G as low as 10(-16) M and a Raman enhancement factor as large as 10(14) were obtained. Simulation results show that two kinds of inter-Ag-NP nanogaps in three-dimensional geometry create a huge number of SERS 'hot spots' where electromagnetic fields are substantially amplified, contributing to the higher SERS sensitivity and lower detection limit. The excellent SERS stability of Ag/SiNWAs is attributed to the presence of the SiO2 nanolayer around Ag NPs that prevented the Ag NP surface from being oxidized. The calibration of the Raman peak intensities of rhodamine 6G and thiram allowed their quantitative detection. Our finding is a significant advance in developing SERS substrates for the fast and quantitative detection of trace organic molecules.

FoxO is required for optimal fitness of the migratory brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae).

The forkhead box O (FoxO) protein is the main transcriptional effector downstream of the insulin/insulin-like signaling pathway and regulates many developmental and physiological processes. Holometabolous insects with loss-of-function mutations in FoxO exhibit phenotypes distinct from those of hemimetabolous insects in which RNA interference was used. Despite the functional importance of FoxO, whether hemimetabolous insects share an evolutionally conserved function of FoxO with holometabolous insects remains to be clarified. We used the clustered regularly interspaced short palindromic repeats/CRISPR-associated 9 (CRISPR/Cas9) genome editing-system to establish a homozygous FoxO-null mutant (NlFoxO4E ) of the wing-dimorphic brown planthopper (BPH) Nilaparvata lugens, an economically important insect pest of rice fields. The phenotypes of NlFoxO4E mutants included extended nymphal duration, shortened lifespan, reduced reproduction, and decreased stress resistance. In addition, depletion of NlFoxO promoted cell proliferation in wing buds and led to 100% long-winged morphs, in stark contrast to short-winged wild-type BPHs. These findings indicate that NlFoxO is highly functionally conserved with its counterpart in holometabolous insects, and is required for optimal fitness of N. lugens. The insights from FoxO studies may facilitate the identification of potential target genes for BPH control applications.

Orco mutagenesis causes deficiencies in olfactory sensitivity and fertility in the migratory brown planthopper, Nilaparvata lugens.

BACKGROUND: The migratory brown planthopper (BPH), Nilaparvata lugens (Hemiptera: Delphacidae), is the most destructive pest affecting rice plants in Asia and feeds exclusively on rice. Studies have investigated the olfactory response of BPHs to the major rice volatile compounds in rice. The insect olfactory co-receptor (Orco) is a crucial component of the olfactory system and is essential for odorant detection. Functional analysis of the Orco gene in BPHs would aid in the identification of their host preference. RESULTS: We identified the BPH Orco homologue (NlOrco) by Blast searching the BPH transcriptome with the Drosophila Orco gene sequence. Spatiotemporal analysis indicated that NlOrco is first expressed in the later egg stage, and is expressed mainly in the antennae in adult females. A NlOrco-knockout line (NlOrco-/- ) was generated through clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated mutagenesis. The NlOrco-/- mutants showed no response to rice volatile compounds and consequently no host-plant preference. In addition, NlOrco-/- mutants exhibited extended nymphal duration and impaired fecundity compared with wild-type BPHs. CONCLUSION: Our findings indicated that BPHs exhibit strong olfactory responses to major rice volatile compounds and suggest that NlOrco is required for the maximal fitness of BPHs. Our results may facilitate the identification of potential target genes or chemical compounds for BPH control applications. © 2022 Society of Chemical Industry.