Rice Planthoppers Research Articles

Effects of ttk on development and courtship of male Nilaparvata lugens.

The transcription product of tramtrack (ttk) is an important transcription factor which plays many roles in the regulation of the development, differentiation and chromosome recombination of organisms. Few studies have been reported on the specific functions of ttk in other insects except Drosophila melanogaster. Our aims are to reveal the ttk effects on development and courtship of male rice pest brown planthopper (BPH), Nilaparvata lugens. In this study, we first assayed spatiotemporal expression of ttk in BPH, then treated the fourth nymphs of BPH with dsttk. We found most individuals died before emerging to adults, the adult eclosion rate was only 18.89%. No courtship behavior was found in individuals injected with dsttk. Further research showed that the main frequency of courtship vibration signal (CVS) 431.3 Hz in the individuals injected with dsttk was significantly higher than 223 Hz in the individuals injected with dsGFP, and female adults nearly had no response to the 431.3 Hz CVS. We found that about 81% of the 4-instar nymphs of BPH treated with dsttk died before they emerged as adults, the successfully emerged adults emitted the 431.3 Hz CVS to which female adults did not respond and lost the ability of courtship. This was first finding about the functions of ttk in rice planthopper and illustrated the potential of ttk as target for RNAi to control rice planthopper. © 2024 Society of Chemical Industry.

Diversity and transmissibility of RNA viruses in the small brown planthopper, Laodelphax striatellus.

In the last decade, advances in the next-generation sequencing technology have unveiled a vast diversity of viruses in insects, particularly RNA viruses in hematophagous insects. However, research on virus diversity and their association with phytophagous insect hosts remains insufficient. This study presents a comprehensive analysis of the RNA virome in the small brown planthopper (SBPH), Laodelphax striatellus, a critical vector of plant viruses. The results indicated that the +ssRNA viruses, especially picorna-like viruses, comprised the core RNA viruses of SBPH that were prevalent in both laboratory and field populations. Moreover, a delicate balance was observed between the viruses and insect hosts. Significantly, some RNA viruses of SBPH could successfully infect and replicate in two other rice planthopper species belonging to different genera. This study provides valuable insights into the RNA virome and its adaptability in a phytophagous insect.

Characterization of Serpin Family Genes in Three Rice Planthopper Species and Their Expression Profiles in Response to Metarhizium Infection

Characterization of Serpin Family Genes in Three Rice Planthopper Species and Their Expression Profiles in Response to Metarhizium Infection

Crucial role of a takeout protein in white-backed planthopper Sogatella furcifera (Horváth) orientation towards its host rice plants.

The takeout (TO) gene family impacts diverse physiological and behavioral functions in insects, yet specific olfactory-associated roles for the family have yet to be fully elucidated. To provide insights into TO function in rice planthoppers, the genomes of three rice planthoppers (white-backed planthopper, brown planthopper and small brown planthopper) were searched for TO homologs and their degree of conservation assessed via chromosomal localization, exon-intron boundaries, phylogenetic relationships and protein domains/motifs. We performed a tissue-specific expression analysis of the 20 TO genes in the white-backed planthopper (WBPH, Sogatella furcifera) and found that SfTO17 is enriched in adult antennae. RNAi-mediated knockdown of SfTO17 impaired WBPH olfaction and reduced host-seeking responses following exposure to rice plants. The binding profile of β-ionone, hexyl benzoate and benzyl benzoate with recombinant SfTO17 was evaluated via competitive fluorescence binding assays. Conformational prediction of SfTO17 coupled with molecular docking analyses revealed several amino acid residues potentially critical for odorant binding. This study demonstrates the olfactory function of SfTO17 in WBPH and highlights its potential as a target for controlling this rice pest. © 2024 Society of Chemical Industry.

Impact of insecticides on natural enemies of planthoppers in direct seeded rice

In the kharif season of 2020, a field experiment was conducted at the Agricultural College Farm, Bapatla to evaluate the impact of some insecticides in combination with the neem products on natural enemies of planthoppers such as green miridbug, Cyrtorhinus lividipennis (Reuter) and spider Lycosa pseudoannulata (Boesenberg and Strand) and Tetragnatha maxillosa (Thorell) in direct seeded rice (DSR). The results concerning the influence of insecticidal treatments, on natural predators such as miridbugs and spiders revealed that neem formulation 1500ppm @ 5ml l-1 with 6.13 miridbugs/hill and 8.83 spiders/10 hills h were at par with the untreated control showing no adverse effects on the predators of rice planthoppers. Among the other treatments, dinotefuran 20SG @ 40g a.i. ha-1 has recorded lowest number of natural predators with 2.77 miridbugs/hill and 5.17 spiders/10 hills, followed by triflumezopyrim 10.6SC @ 25g a.i. ha-1 with 2.93 miridbugs/hill and 5.27 spiders/10 hills; Pymetrozine 50WG @ 150g a.i. ha-1 with 3.07 miridbugs/hill and 5.50 spiders/10 hills which differed significantly from the untreated control.

Horizontal transmission of a rice bacterial pathogen Pantoea ananatis among plants by rice planthoppers.

Pantoea ananatis is a bacterium commonly found in various agronomic crops and agricultural pests. In this study, we present findings on a genome-reduced strain of P. ananatis, known as Lstr, which was initially isolated from Laodelphax striatellus (small brown rice planthopper, SBPH). We identified Lstr as a plant pathogen causing disease in rice using Koch's postulates. The pathogenicity of Lstr on rice is comparable to that of Xanthomonas oryzae pv. oryzae, the main causative agent of rice bacterial blight. Through a series of experiments involving live insects, molecular investigations, and microscopy, we find that Lstr can accumulate within SBPH. Subsequently, Lstr can be transmitted from SBPH to rice plants, resulting in leaf blight, and can also be transmitted to other SBPH individuals. Collectively, our results suggest that SBPH serves as a vector for P. ananatis Lstr in rice plants. P. ananatis may encounter susceptible insect populations and become endemic through horizontal transmission from these insects. This could also be valuable for predicting future occurrences of bacterial leaf blight in rice and other crops caused by P. ananatis.

Effects of a Bank Plant on the Control of Rice Planthoppers: A Field Study

Effects of a Bank Plant on the Control of Rice Planthoppers: A Field Study

Virulence Adaptation by Rice Planthoppers and Leafhoppers to Resistance Genes and Loci: A Review.

In recent decades, research on developing and deploying resistant rice has accelerated due to the availability of modern molecular tools and, in particular, advances in marker-assisted selection. However, progress in understanding virulence adaptation has been relatively slow. This review tracks patterns in virulence adaptation to resistance genes (particularly Bph1, bph2, Bph3, and bph4) and examines the nature of virulence based on selection experiments, responses by virulent populations to differential rice varieties (i.e., varieties with different resistance genes), and breeding experiments that interpret the genetic mechanisms underlying adaptation. The review proposes that varietal resistance is best regarded as a combination of minor and major resistance traits against which planthoppers develop partial or complete virulence through heritable improvements that are reversable or through evolutionary adaptation, respectively. Agronomic practices, deployment patterns, and herbivore population pressures determine the rates of adaptation, and there is growing evidence that pesticide detoxification mechanisms can accelerate virulence adaptation. Research to delay adaptation has mainly focused on gene pyramiding (i.e., including ≥ two major genes in a variety) and multilines (i.e., including ≥ two resistant varieties in a field or landscape); however, these strategies have not been adequately tested and, if not managed properly, could inadvertently accelerate adaptation compared to sequential deployment. Several research gaps remain and considerable improvements in research methods are required to better understand and manage virulence adaptation.

Redescription of Paracentrobia (Paracentrobia) mira (Girault) (Hymenoptera: Trichogrammatidae), with two new synonyms

Both sexes of Paracentrobia (Paracentrobia) mira (Girault) (Hymenoptera: Trichogrammatidae) are redescribed and illustrated based on type material from Queensland, Australia and additional, non-type specimens from Oceania. Paracentrobia sexguttata (Girault), syn. nov., originally described from Queensland, and Paracentrobia (Paracentrobia) yasumatsui Subba Rao, syn. nov., originally described from Thailand, are synonymized under P. (Paracentrobia) mira. This species is a known egg parasitoid of rice leafhoppers and planthoppers (Hemiptera: Cicadellidae and Delphacidae) of economic importance in Asia.

Genetic diversity analysis of Saccharosydne procerus in Hunan region, China.

Saccharosydne procerus serves as a significant alternative host for parasitoids of the important rice pest, rice planthoppers. Rearing S. procerus on the water bamboo plants near rice field can provide a parasitic site for parasitic wasps during the idle period of rice fields, thereby stabilizing the number of parasitoids and suppressing the number of rice planthoppers in the field. However, limited understanding of genetic diversity of S. procerus restricts its application. Therefore, this study aims to analyze the genetic diversity of S. procerus in Hunan region. In this study, 16 geographical populations of the S. procerus from the Hunan region were used. After screening, ISSR primers were employed for polymorphism detection. POPGENE32 software was used for genetic diversity analysis, and UPGMA clustering was applied for statistical analysis of different geographical populations to generate an evolutionary tree. Eleven ISSR primers were screened, resulting in the detection of 194 amplification locus, of which 126 were polymorphic. The average percentage of polymorphic locus was 64.95%. The mean Nei's gene diversity (H) was 0.2475, the mean Shannon's Information index (I) was 0.3708, and the Genetic diversity index among populations (Gst) was 0.3800. Cluster analysis identified three groups, with most populations concentrated in the second group, indicating no clear genetic structure. This suggests that the 16 populations of S. procerus exhibit high levels of genetic diversity.

Genetic variations and gene expression profiles of Rice Black-streaked dwarf virus (RBSDV) in different host plants and insect vectors: insights from RNA-Seq analysis

Rice black-streaked dwarf virus (RBSDV) is an etiological agent of a destructive disease infecting some economically important crops from the Gramineae family in Asia. While RBSDV causes high yield losses, genetic characteristics of replicative viral populations have not been investigated within different host plants and insect vectors. Herein, eleven publicly available RNA-Seq datasets from Chinese RBSDV-infected rice, maize, and viruliferous planthopper (Laodelphax striatellus) were obtained from the NCBI database. The patterns of SNP and RNA expression profiles of expected RBSDV populations were analyzed by CLC Workbench 20 and Geneious Prime software. These analyses discovered 2,646 mutations with codon changes in RBSDV whole transcriptome and forty-seven co-mutated hotspots with high variant frequency within the crucial regions of S5-1, S5-2, S6, S7-1, S7-2, S9, and S10 open reading frames (ORFs) which are responsible for some virulence and host range functions. Moreover, three joint mutations are located on the three-dimensional protein of P9-1. The infected RBSDV-susceptible rice cultivar KTWYJ3 and indigenous planthopper datasets showed more co-mutated hotspot numbers than others. Our analyses showed the expression patterns of viral genomic fragments varied depending on the host type. Unlike planthopper, S5-1, S2, S6, and S9-1 ORFs, respectively had the greatest read numbers in host plants; and S5-2, S9-2, and S7-2 were expressed in the lowest level. These findings underscore virus/host complexes are effective in the genetic variations and gene expression profiles of plant viruses. Our analysis revealed no evidence of recombination events. Interestingly, the negative selection was observed at 12 RBSDV ORFs, except for position 1015 in the P1 protein, where a positive selection was detected. The research highlights the potential of SRA datasets for analysis of the virus cycle and enhances our understanding of RBSDV’s genetic diversity and host specificity.

Dispersal patterns and potential distribution prediction of three rice planthopper species in China based on the ensemble model

AbstractThree rice planthopper species, Nilaparvata lugens, Sogatella furcifera and Laodelphax striatellus, are destructive rice pests that cause serious economic losses in major rice‐producing regions of China. Understanding their dispersal patterns and potential distribution areas is crucial for effective management and control. Based on historical climate data and simulated future climate data combined with species occurrence data, the dispersal patterns of three planthopper species were analysed and their potential distributions were predicted. The results showed that from 1993 to 2022, the suitable areas for the three rice planthoppers gradually expanded. By 2022, the total suitable area for S. furcifera reached 478.35 × 104 km2, followed by 376.02 × 104 km2 for L. striatellus and 264.97 × 104 km2 for N. lugens. The optimum area for S. furcifera exhibited the most significant increase, expanding by 136.07 × 104 km2. The species has extended its range from southern China to the northeastern and northwestern regions within the past three decades. The suitable areas for L. striatellus and N. lugens did not show a significant spread trend. In addition, compared to that in 2022, the total suitable area for the three rice planthopper species increased slightly from 2041 to 2060. The study revealed that the wettest monthly rainfall and the lowest temperature were the most influential factors affecting the distributions of these planthopper species. This study provides valuable insights into the dispersal patterns and potential distribution of rice planthoppers in China and provides a theoretical basis for effective prevention and control strategies for destructive rice pests.

The Low Congruence between Plant and Animal Diversity in Field Ridges of Intensively Managed Paddy Landscapes, China.

Field ridges are commonly viewed as the stable semi-natural habitats for maintaining plant diversity in the agricultural landscape. The high plant diversity could further support higher animal diversity. But following the adoption of well-facilitated farmland construction measures in China, many field ridges have been disproportionately neglected or destroyed. Empirical studies delineating the relationships between plant and animal diversity in these field ridges in the paddy landscape remain scant, especially in China, which has the most rice production. A two-year field ridge evaluation was conducted in the Chengdu Plain area, covering 30 paddy landscapes. This investigation scrutinizes the shape attributes of field ridges, their plant diversity, and the associated animal α-diversity and community compositions, including spiders, carabids, birds, frogs, and rice planthoppers. In the results of Pearson's correlation analysis, a significant inconsistent correlation was observed between plant diversity and animal diversity. The analysis of community structure heterogeneity also revealed no correspondence for species composition between plant and animal communities (i.e., spiders, carabids, and birds), while the non-metric multidimensional scale analysis indicated a substantial difference in the species composition of spiders or plants even within the same field ridge between 2020 and 2021. We argue that the implementation of intensive management practices in paddy landscapes, such as machine ploughing and harvesting and herbicide spraying with drones, leads to a scarcity of stable animal and plant communities in field ridges. Therefore, besides retaining these field ridges in paddy landscapes, maintaining the long-term stable ridges by refraining from herbicide spraying or artificial weeding, as well as avoiding winter wheat cultivating in field ridges, will contribute to protecting biodiversity of field ridges as semi-natural habitats.

The mRNA surveillance factor Pelo restricts rice virus propagation in insect vectors and host plants

Many devastating plant viruses are transmitted by insect vectors among plant hosts in a persistent-propagative manner. Pelota (Pelo) is an evolutionarily conserved protein involved in the mRNA surveillance system. In this study, it was found that the accumulation of Pelo proteins are slightly decreased during the propagation of the fijivirus southern rice black-streaked dwarf virus (SRBSDV) in rice and transmission vector planthopper (Sogatella furcifera). The tubular protein P7-1 encoded by SRBSDV interacted with Pelo of rice or planthopper vector. Overexpression or knockdown of Pelo expression inhibits the formation of P7-1 tubules in insect cells, further exerting antiviral activity. Furthermore, overexpression or knockout of Pelo expression in transgenic rice plants also inhibits the effective propagation of SRBSDV as well as two other rice viruses of different families. The slight reduction of Pelo accumulation during SRBSDV propagation in rice and insect vectors would avoid Pelo-mediated excessive inhibition of P7-1 tubule formation, ensuring effective virus propagation. Our findings provide insights into how the up- or down-regulated expression of Pelo in rice hosts and insect vectors elevate their resistance to rice viruses.

Expression characterization of miR‐6826‐3p in Pardosa pseudoannulata (Araneae: Lycosidae) under high temperature stress

AbstractPardosa pseudoannulata is key predator in rice ecosystems; it plays a crucial role in rice pest biological control, effectively managing major rice pests such as rice planthopper. At present, there are few related studies on spiders' microRNA (miRNA). Consequently, we initiate a study on miR‐6826‐3p in P. pseudoannulata in response to high temperatures. First, we identified a total of 686 target genes of miR‐6826‐3p, 439 target genes had annotated results in the database, primarily involved in transcription and metabolism functions. Subsequently, quantitative real‐time PCR was employed to assess the relative expression levels of miR‐6826‐3p in P. pseudoannulata under different temperatures (31, 34, 37, 40°C) and various durations (1, 2, 4, 8, 12 h). The results revealed that compared to the control group (25°C), the relative expression level of miR‐6826‐3p in female spiders significantly increased under the same temperature and different duration stresses. The expression level of miR‐6826‐3p in male spiders showed an initial increase followed by a decrease trend, with relatively lower expression levels after 1 and 12 h at the same temperature conditions. Furthermore, under the same duration of stress, compared to the control group (25°C), the relative expression level of miR‐6826‐3p in female spiders significantly increased at different temperatures. These results demonstrate that P. pseudoannulata miR‐6826‐3p plays a significant role in response to high‐temperature stress. The research findings can provide a basis for future in‐depth studies on the miRNA functional of P. pseudoannulata, aiding in the elucidation of the regulatory mechanisms of P. pseudoannulata miRNAs in response to high‐temperature environments.

Tank-mix adjuvants improved spray performance and biological efficacy in rice insecticide application with unmanned aerial vehicle sprayer.

The use of unmanned aerial vehicles (UAVs) for the application of plant protection products (PPPs) in paddy fields is becoming increasingly prevalent worldwide. Despite its growing usage, UAV spraying for rice pest control faces practical challenges, including limited canopy penetration, uneven deposition, and significant spray drift. This study investigated the impact of two tank-mix adjuvants, Wonderful Rosin (Adjuvant-1) and Tiandun (Adjuvant-2), at six volume concentrations, on the spray liquid's physicochemical properties, spray drift, plant deposition, and the biological efficacy of rice insecticides using a quadrotor UAV sprayer. The physicochemical characteristics of the spray liquid influenced spray performance and biological efficacy. Incorporating Adjuvant-1 and Adjuvant-2 led to a decrease in surface tension and contact angle while increasing the viscosity of the spray solution. These alterations in surface tension and viscosity contributed to an optimized droplet size distribution, reduced spray drift, enhanced deposition uniformity and penetration, and improved control efficacy against the rice planthopper in UAV applications. The highest control efficacy was observed at a concentration of 0.5%, showing an improvement of 35.12% (Adjuvant-1) and 20.23% (Adjuvant-2) over applications without tank-mix adjuvant 7 days after treatment. The judicious selection of tank-mix adjuvants for UAV PPP applications can significantly enhance spray performance and biological efficacy in controlling rice insects. This study's findings offer valuable insights for integrating tank-mix adjuvants into UAV spraying applications. © 2024 Society of Chemical Industry.

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

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. 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. 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.

Cross-kingdom RNA interference mediated by insect salivary microRNAs may suppress plant immunity

Communication between insects and plants relies on the exchange of bioactive molecules that traverse the species interface. Although proteinic effectors have been extensively studied, our knowledge of other molecules involved in this process remains limited. In this study, we investigate the role of salivary microRNAs (miRNAs) from the rice planthopper Nilaparvata lugens in suppressing plant immunity. A total of three miRNAs were confirmed to be secreted into host plants during insect feeding. Notably, the sequence-conserved miR-7-5P is specifically expressed in the salivary glands of N. lugens and is secreted into saliva, distinguishing it significantly from homologues found in other insects. Silencing miR-7-5P negatively affects N. lugens feeding on rice plants, but not on artificial diets. The impaired feeding performance of miR-7-5P-silenced insects can be rescued by transgenic plants overexpressing miR-7-5P. Through target prediction and experimental testing, we demonstrate that miR-7-5P targets multiple plant genes, including the immune-associated bZIP transcription factor 43 (OsbZIP43). Infestation of rice plants by miR-7-5P-silenced insects leads to the increased expression of OsbZIP43, while the presence of miR-7-5P counteracts this upregulation effect. Furthermore, overexpressing OsbZIP43 confers plant resistance against insects which can be subverted by miR-7-5P. Our findings suggest a mechanism by which herbivorous insects have evolved salivary miRNAs to suppress plant immunity, expanding our understanding of cross-kingdom RNA interference between interacting organisms.

OsmiR319-OsPCF5 modulate resistance to brown planthopper in rice through association with MYB proteins

BackgroundThe brown planthopper (BPH) is a kind of piercing-sucking insect specific to rice, with the damage tops the list of pathogens and insects in recent years. microRNAs (miRNAs) are pivotal regulators of plant–environment interactions, while the mechanism underlying their function against insects is largely unknown.ResultsHere, we confirmed that OsmiR319, an ancient and conserved miRNA, negatively regulated resistance to BPHs, with overexpression of OsmiR319 susceptible to BPH, while suppression of OsmiR319 resistant to BPH in comparison with wild type. Meanwhile, we identified several targets of OsmiR319 that may mediate BPH resistance. Among them, OsPCF5 was the most obviously induced by BPH feeding, and over expression of OsPCF5 was resistance to BPH. In addition, various biochemical assays verified that OsPCF5 interacted with several MYB proteins, such as OsMYB22, OsMYB30, and OsMYB30C.Genetically, we revealed that both OsMYB22 and OsMYB30C positively regulated BPH resistance. Genetic interaction analyses confirmed that OsMYB22 and OsMYB30C both function in the same genetic pathway with OsmiR319b to mediate BPH resistance.ConclusionsAltogether, we revealed that OsPCF5 regulates BPH resistance via association with several MYB proteins downstream of OsmiR319, these MYB proteins might function as regulators of BPH resistance through regulating the phenylpropane synthesis.

Genome-wide association study and genomic prediction for resistance to brown planthopper in rice.

The brown planthopper (BPH) is the most destructive insect pest that threatens rice production globally. Developing rice varieties incorporating BPH-resistant genes has proven to be an effective control measure against BPH. In this study, we assessed the resistance of a core collection consisting of 502 rice germplasms by evaluating resistance scores, weight gain rates and honeydew excretions. A total of 117 rice varieties (23.31%) exhibited resistance to BPH. Genome-wide association studies (GWAS) were performed on both the entire panel of 502 rice varieties and its subspecies, and 6 loci were significantly associated with resistance scores (P value < 1.0e-8). Within these loci, we identified eight candidate genes encoding receptor-like protein kinase (RLK), nucleotide-binding and leucine-rich repeat (NB-LRR), or LRR proteins. Two loci had not been detected in previous study and were entirely novel. Furthermore, we evaluated the predictive ability of genomic selection for resistance to BPH. The results revealed that the highest prediction accuracy for BPH resistance reached 0.633. As expected, the prediction accuracy increased progressively with an increasing number of SNPs, and a total of 6.7K SNPs displayed comparable accuracy to 268K SNPs. Among various statistical models tested, the random forest model exhibited superior predictive accuracy. Moreover, increasing the size of training population improved prediction accuracy; however, there was no significant difference in prediction accuracy between a training population size of 737 and 1179. Additionally, when there existed close genetic relatedness between the training and validation populations, higher prediction accuracies were observed compared to scenarios when they were genetically distant. These findings provide valuable resistance candidate genes and germplasm resources and are crucial for the application of genomic selection for breeding durable BPH-resistant rice varieties.