Search Results (177)

The brown planthopper (BPH, Nilaparvata lugens) is a major insect pest of rice (Oryza sativa L.) causing severe yield losses across Asia. Although the resistance gene OsBph32 from the cultivar Ptb33 enhances BPH resistance, its molecular and physiological mechanisms remain unclear. Here, we investigated its function using OsBph32-overexpressing lines combined with physiological, transcriptomic, and metabolomic analyses. Overexpression of OsBph32 in the susceptible cultivar 9311 significantly increased resistance to BPH, as indicated by reduced plant damage and suppressed insect growth. This was associated with increased reactive oxygen species accumulation and callose deposition, suggesting activation of early defense responses. Multi-omics analyses revealed that OsBph32 is associated with transcriptional changes in genes involved in cell wall biosynthesis, phenylpropanoid metabolism, and carbon metabolism. Metabolomic profiling further showed increased accumulation of flavonoids, phenolamides, and lignin-related metabolites under BPH infestation, together with changes in carbon metabolism and starch accumulation. Collectively, these results suggest that OsBph32 is associated with coordinated changes in structural reinforcement, secondary metabolism, and carbon metabolism during insect attack, which may contribute to enhanced rice resistance and provide new insights into non-NLR-mediated insect defense mechanisms in plants. Full article

Reliable detection of small agricultural targets is fundamental to precision crop protection, phenotyping, yield estimation, and robotic intervention. Typical examples include detecting aphids such as Aphis gossypii, whiteflies such as Bemisia tabaci, planthoppers such as Nilaparvata lugens, and other tiny pests on sticky traps or crop canopies for early warning, identifying crop-like weed seedlings for site-specific herbicide spraying, locating early disease lesions for targeted treatment, and detecting young fruits, flowers, or wheat heads for yield estimation and robotic manipulation. Agricultural small-object detection differs from generic small-object detection because target visibility is jointly determined by pixel area, physical size, imaging distance, ground sampling distance, canopy structure, biological similarity, and task-specific intervention requirements. Existing reviews have summarized agricultural object detection or general small-object detection, but they rarely connect agricultural failure modes with detector-level mechanisms and reproducible evaluation practices. This review addresses this gap through a mechanism-oriented synthesis of agricultural small-object detection. First, we revisit the limitations of the COCO-style 32²-pixel threshold and propose an agricultural scale-reporting framework that combines pixel area, physical scale, relative image occupancy, and acquisition geometry. Second, we organize recent methods according to the mechanisms by which they address detail loss, scale shift, occlusion, dense distributions, foreground–background confusion, localization uncertainty, and edge-deployment constraints. Third, we summarize public datasets, quantitative evaluation metrics, reporting checklists, and real-device deployment evidence to support fair and field-oriented comparison. Finally, we identify future directions in multimodal sensing, foundation-model adaptation, label-efficient learning, and hardware-aware optimization. By linking agricultural scene characteristics, detector mechanisms, and evaluation requirements, this review aims to provide a more actionable framework for developing robust small-object detection systems in precision agriculture. Full article

The southern rice black-streaked dwarf virus (SRBSDV) is transmitted by the white-backed planthopper (WBPH), Sogatella furcifera, but not by the co-occurring brown planthopper (BPH), Nilaparvata lugens. Understanding the influence of virus infection of host plants on the performance of close-related vector and non-vector species is an interesting topic for exploring virus–plant–herbivore interactions. This study investigates how SRBSDV infection of rice plants affects the performance of WBPH and BPH and the plant defense responses. Differential performance of the two planthopper species was observed. On infected plants, WBPH displayed prolonged male nymphal development, increased adult longevity, enhanced feeding, and reduced fecundity, which contrasts the reduced nymph survival and fecundity in BPH. SRBSDV infection triggered an increase in salicylic acid (SA) levels and upregulated the expression of SA-related genes (ICS1 and NPR1) in response to WBPH feeding, but not to BPH feeding. These results show that SRBSDV reshapes the host plant defense in a manner that alters key vector traits favoring virus transmission while impairing the fitness of a competing non-vector, which advances current understanding of virus–plant–herbivore interaction. Full article

The deployment of insect-resistant rice cultivars is a sustainable strategy for pest control, while the adaptation of pest insects to resistance limits the efficiency of resistant rice varieties. The cytochrome P450 gene CYP4C61 was previously identified as a key locus underlying brown planthopper (BPH, Nilaparvata lugens) adaptation to the resistant rice variety IR36, but its metabolic function remained unknown. Here, we integrated RNAi-mediated gene silencing, untargeted metabolomics, and transcriptomics to elucidate the metabolic role of CYP4C61 in the BPH population virulent to resistant rice IR36. CYP4C61 silencing significantly impaired BPH fitness, including reduced body weight, increased mortality, disrupted feeding behavior, and a progressive body darkening of BPH reared on IR36 rice, reflecting dopamine accumulation entering the melanization branch. Metabolomic analysis identified 240 differentially abundant metabolites in silenced BPH on IR36, revealing a pattern of precursor reduction and product accumulation in the dopamine pathway. Transcriptomic analysis also revealed that CYP4C61 knockdown altered gene expression in the dopamine pathway in a host-dependent manner. Enzyme-linked immunosorbent assay validated dopamine accumulation after CYP4C61 knockdown exclusively in the IR36 background. Our integrated multi-omics evidence indicates that CYP4C61 contributes to dopamine homeostasis in the virulent BPH, providing a mechanistic link between a P450 gene and dopamine-mediated insect adaptation to resistant host plants. Full article

Volatile organic compounds (VOCs) have garnered substantial research interest in recent years due to their biodegradability, low toxicity, and potent antimicrobial properties against various plant pathogens. As a typical herbivore-induced plant volatile (HIPV) elicited by Nilaparvata lugens (Brown planthopper, BPH), (E)-2-hexenal has been identified as a promising natural antimicrobial agent. In this study, we investigated the protective potential of (E)-2-hexenal against Rhizoctonia solani (R. solani) in rice, focusing on both its direct antifungal activity and host-mediated defense mechanisms. In vitro antifungal assays demonstrated that treatment with 100 μL/mL (E)-2-hexenal resulted in a 91.07% inhibition of R. solani mycelial growth after 48 h. Scanning electron microscopy (SEM) observation and chitinase activity analysis revealed that (E)-2-hexenal suppressed fungal growth by disrupting the structural integrity of the pathogen cell wall. Furthermore, 100 μL/mL (E)-2-hexenal effectively conferred protection to detached rice leaves. Whole-plant inoculation assays confirmed that (E)-2-hexenal pretreatment significantly alleviated disease symptoms and triggered systemic resistance in rice plants. Physiological and biochemical analyses showed that (E)-2-hexenal treatment enhanced the activities of defense-related enzymes, elevated hydrogen peroxide (H₂O₂) levels, and promoted the accumulation of defensive metabolites in rice leaves. HPLC-MS quantification further revealed significant increases in the endogenous levels of jasmonic acid (JA) and salicylic acid (SA). Transcriptomic KEGG pathway enrichment analysis indicated that differentially expressed genes (DEGs) were mainly involved in alpha-linolenic acid metabolism, diterpenoid biosynthesis, phenylpropanoid biosynthesis, plant–pathogen interaction, and plant hormone signal transduction. Collectively, these results suggest that (E)-2-hexenal enhances rice resistance to sheath blight disease via a dual-action mechanism: direct inhibition of fungal development and activation of host immune responses. Our findings highlight the potential application of (E)-2-hexenal and other VOCs in developing eco-friendly strategies for sustainable rice disease management. Full article

Clothianidin (CLO) is a widely used neonicotinoid insecticide in agricultural systems and may pose risks to non-target aquatic organisms, including amphibians. Here, we evaluated acute and sublethal effects of CLO on Fejervarya cancrivora tadpoles, an important predator of insect pests in rice paddy ecosystems. Acute toxicity tests (96 h) yielded an LC₅₀ of 50.41 mg a.i./L (with LC₁₀, LC₂₅ and LC₃₀ values of 15.35, 31.96 and 36.07 mg a.i./L, respectively). Sublethal exposure at these concentrations significantly reduced body weight, whole-body length, and hindlimb length during metamorphosis. CLO also altered thyroid hormone regulation, with T4 showing a dose-dependent increase, while T3 was elevated relative to controls but showed comparatively limited additional sensitivity to concentration and exposure duration. Locomotor activity was impaired under sublethal CLO exposure, reflected by reduced swimming distance and speed. In addition, frogs that developed from CLO-exposed tadpoles exhibited decreased feeding efficiency on brown planthoppers (Nilaparvata lugens) across developmental stages 46–48. Together, these findings demonstrate that CLO can affect amphibian development, endocrine regulation, and behavior at sublethal levels, highlighting the need to incorporate sublethal endpoints into ecological risk assessment and to promote pest management strategies that reduce impacts on biodiversity and ecosystem services. Full article

The white-backed planthopper, Sogatella furcifera, and the brown planthopper, Nilaparvata lugens, severely impact rice production, necessitating effective selection methods for resistant cultivars. S. furcifera poses a significant threat to rice cultivation, particularly in Asia. Through this study, we aimed to establish an effective approach to identifying resistant rice varieties based on feeding behavior, physiological and chemical responses, and genetic analysis. Three key activities were involved: (1) evaluation of planthopper feeding behavior utilizing the honeydew drop method, the electrical penetration graph technique, and growth rate analysis; (2) investigation into the physiological and chemical traits of rice; and (3) analysis of resistance-related gene expression. The results indicated larger honeydew drop areas, fewer and shorter probing events, and structural defenses such as increased trichome density in resistant rice genotypes, likely hindering insect attachment and feeding. We confirmed the suitability of the growth rate method for resistance screening. Gene expression analysis identified PR10a upregulation in resistant rice, suggesting a molecular basis for resistance. This study enables the selection of rice varieties resistant to planthoppers, supporting sustainable pest management and breeding programs. The findings support sustainable pest management by enabling the targeted selection of resistant varieties, ultimately aiding in the development of rice genotypes with enhanced resistance across growth stages. Full article

Rice volatiles play a crucial role in mediating resistance to the brown planthopper (Nilaparvata lugens Stål, Hemiptera: Delphacidae), a major pest of rice crops. In this study, we analyzed secondary metabolites from rice plants to identify compounds associated with insect behavior. A total of 31 volatile metabolites were detected, among which 16 differed significantly between 51 resistant or susceptible varieties. Fifteen volatiles were more abundant in susceptible plants, while one was enriched in resistant varieties. Electrophysiological (EAG) and Y-tube olfactometer assays revealed that both male and female adults exhibited positive chemotaxis toward five volatiles: Cyclohexanone, 2,2,6-trimethyl-; 3-Cyclohexen-1-one, 3,5,5-trimethyl-; (+)-Isomenthol; Benzoic acid, 2-hydroxy-, methyl ester; and 2-Methoxy-4-vinylphenol. In contrast, male adults were repelled by Benzaldehyde, 3-ethyl-, and 3-Buten-2-one, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-. These results indicate that characteristic volatiles serve as functional cues for host selection and may act as phytochemical markers for assessing rice resistance. The findings provide new insights into plant–insect chemical interactions and suggest potential strategies for environmentally friendly pest management, including the use of attractant- or repellent-based approaches and breeding for optimized volatile profiles to control N. lugens. Full article

The Brown Planthopper, Nilaparvata lugens (Stål.) (Hemiptera: Delphinidae), is one of the most destructive pests of rice. Its reproductive and developmental traits are influenced by various environmental and biological factors including endosymbiotic microorganisms. Arsenophonus, a widespread endosymbiotic bacterium of insects, can affect host fitness and metabolic processes. This study investigates the role of Arsenophonus in modulating the developmental and reproductive traits of N. lugens fed on transgenic cry30Fa1 rice (KF30-14) and its parent variety Minghui 86 (MH86). Life table analysis revealed that Arsenophonus infection (Ars⁺) increased the development time and reduced the reproductive capacity of N. lugens, especially those feeding on KF30-14. The first-instar nymphs in MH86 Ars⁺ (infected) exhibited slower development compared to MH86 Ars⁻ (uninfected). Similarly, the third and fourth-instar nymphs in KF30-14 Ars⁺ exhibited prolonged development time compared to KF30-14 Ars⁻. In addition, KF30-14 Ars⁺ females had significantly reduced reproductive capacity, smaller ovarian tubules and lower relative expression levels of reproduction-related genes including Trehalose transporter (Tret), Vitellogenin (Vg) and Cytochrome P450 hydroxylase (cyp314a1), while Juvenile hormone acid methyltransferase (JHAMT) expression was upregulated. RNA sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed significant enrichment of genes involved in lipid, amino acid, and vitamin metabolisms, with Long-chain acyl-CoA synthetase implicated as a key regulator of lipid metabolism and reproductive fitness. These results highlight the complex interactions between endosymbionts, host plants and pest biology, offering a solid foundation for sustainable approaches to control N. lugens in rice production systems. Full article

Cyrtorhinus lividipennis, a key natural enemy of the brown planthopper, Nilaparvata lugens, has been observed to tolerate short-term high-temperature exposure; however, the physiological and molecular mechanisms underlying this heat tolerance remain unclear, which may hinder its effective conservation and utilization. Here, we combined physiological and biochemical assays with transcriptome sequencing to elucidate the physiological and molecular mechanisms of heat tolerance in C. lividipennis following 1 h exposure to three temperatures: 26 °C (control), 33 °C (moderate heat stress), and 40 °C (severe heat stress). At 40 °C, sorbitol, trehalose, lipid, and glycogen contents increased significantly, whereas glycerol levels declined. Transcriptomic profiling revealed temperature-dependent DEGs enriched in starch and sucrose metabolism, galactose metabolism, glycerolipid metabolism, oxidative phosphorylation, and protein folding, sorting, and degradation, with pronounced temperature-dependent upregulation of heat shock protein (HSP) gene families. Together, these results demonstrate that C. lividipennis coordinates its heat stress response through soluble polyol accumulation, which is known to act as a compatible osmolytes that help stabilize proteins and membranes and mitigate thermal damage, energy metabolic reprogramming, and HSP-mediated proteostasis, thereby providing a theoretical basis for its conservation and utilization in sustainable paddy agroecosystems. Full article

Bats provide essential ecosystem services, particularly in regulating insect populations within agricultural landscapes. However, research on bat–insect interactions in Malaysian rice fields remains limited. This study examined bat diversity and insect abundance in the rice field area of Gunung Keriang, Kedah, using two harp traps, two mist nets and a light trap at three selected sites. A total of 2499 bats representing 27 species were captured, alongside 161,539 insects from 11 orders. Rhinolophus pusillus was the dominant bat species across all seasons. During the dry season, Chilo polychrysus (stem borer) was the dominant insect pest, whereas Nilaparvata lugens (brown planthopper) prevailed during the wet season. Insects from the order Coleoptera, dominant in the dry season, are likely consumed by larger bat species with stronger bite forces. Bat foraging activity peaked concurrently with insect emergence, corresponding to periods of high food availability. Statistical analysis revealed significant associations between bat activity, temperature, and rainfall, but not insect abundance. These findings underscore the ecological importance of bats as natural pest regulators in rice field ecosystems and highlight their potential role in promoting sustainable, ecosystem-based agricultural management. Full article

Sometimes, crop breeding varieties demonstrate high resistance to target insects under laboratory conditions but exhibit significantly low resistance in the field. This research aimed to explain this phenomenon based on inter-species interactions among insects, as herbivory by one insect species can trigger physiological changes in plants that enhance their attraction to other insect species. The striped stem borer (SSB), Chilo suppressalis (Walker), and the brown planthopper (BPH), Nilaparvata lugens (Stål), are pests of rice (Oryza sativa L.) that cause major losses in grain production. In this study, we investigated BPH performance and behavior on the planthopper-resistant rice variety “Mudgo” with pre-feeding of SSB. BPHs showed better growth and development, as well as feeding behavior, on SSB-damaged plants compared to undamaged plants. Then, gene expression and phytohormone analysis revealed that jasmonic acid (JA) biosynthesis was induced by SSB feeding. The JA pathway is a central defense signaling hub in rice responding to chewing herbivores like SSB; however, our findings reveal that its induction can have contrasting ecological consequences, inadvertently reducing resistance to a subsequent piercing-sucking pest (BPH). Finally, we discovered that volatile emissions induced by SSB damage attracted BPH and benefited its development. In summary, we found that JA biosynthesis triggered by SSB herbivory played a vital role in rice defense against BPH. This provides insight into the molecular and biochemical mechanisms underlying BPH preferences for SSB-damaged rice plants. Our study emphasizes the crucial role of inter-species interactions in enhancing host plant resistance to insect pests and evaluating germplasm resistance. These findings can serve as a basis for controlling BPH. Full article

Rice plays a pivotal role in global food security, particularly for Asian populations. However, its production is significantly threatened by insect pests, with Chilo suppressalis being a major pest in Asian rice-growing regions. Therefore, developing accurate predictive models for C. suppressalis outbreaks is essential. This study presents a novel time series forecasting model (named ESD-TripleStream) for C. suppressalis population dynamics based on a multi-stream structure, which addresses the limitations of existing approaches, which often omit the further decomposability of and the timestamp information in the time series. This model integrates Exponential Smoothing Decomposition (ESD) to separate the trend and seasonal components of time series data, along with a temporal feature stream to form a three-stream network to capture multi-scale periodic patterns and temporal dependencies. For our evaluation, we collected and constructed a novel dataset, referred to as HNRP-6R, which includes rice pest monitoring data from the past two decades (2000–2022) alongside 13 meteorological factors across six key rice producing regions in Hunan Province, southern China. ESD-TripleStream was evaluated across short-term and medium-term C. suppressalis population prediction scales using HNRP-6R, demonstrating state-of-the-art performance. Specifically, in short-term prediction, ESD-TripleStream achieved a 31.8% reduction in Mean Squared Error (MSE) and 26.55% reduction in Mean Absolute Error (MAE) compared to the PatchMLP model, while outperforming the transformer-based TimeXer by 14.43% in MSE and 9.8% in MAE. For medium-term prediction, ESD-TripleStream has both MSE and MAE significantly lower than those of baseline models such as P-sLSTM and xPatch. Furthermore, generalization tests on Nilaparvata lugens (N. lugens) population prediction demonstrated the model’s adaptability to diverse pest dynamics. Full article

Nilaparvata lugens is a migratory pest with high fecundity and outstanding drug resistance, which poses a devastating danger to rice production. This study investigated the reproductive regulation mechanism of N. lugens, specifically silencing the trehalose-6-phosphate synthase gene (TPS) via RNAi to elucidate how TPS governs the trehalose metabolic network through modulation of trehalose biosynthesis. Insect fecundity hinges on the synchronized progression of oogenesis and the tightly controlled expression of vitellogenin (Vg). In N. lugens, this coordination is orchestrated by an integrated molecular network that converges juvenile hormone signaling (JH), 20-hydroxyecdysone pathways (20E), insulin/IGF signaling (IIS), and the target of rapamycin cascade (TOR), collectively dictating the reproductive output of the species. Using TPS knockdown as the entry point, this study dissects the lipid-metabolic circuitry of N. lugens and uncovers how hormonal signaling cascades orchestrate reproduction by precisely modulating vitellogenin (Vg) and its cognate receptor VgR. Synthesized double-stranded terpene synthase genes (dsTPSs) can degrade mRNA, inhibit protein translation, and ultimately lead to the silencing of TPS genes, simultaneously crippling energy provision and hormonal signaling to orchestrate a multi-pronged suppression of reproduction. This dual-action intervention offers a promising molecular target for environmentally friendly management of N. lugens. Full article

The use of fungal entomopathogens, such as Metarhizium anisopliae, is a promising alternative for pest biocontrol but suffers the disadvantage of a relatively slower killing speed when compared with chemical pesticides. Nilaparvata lugens (brown planthopper, BPH) is a destructive sap-sucking pest that seriously threatens rice production worldwide. In the present study, we characterized a key immune-regulating protein, Spätzle (SPZ), encoding gene NlSPZ5 in BPH, and constructed a transgenic strain of M. anisopliae that expressed a specific dsRNA targeting the NlSPZ5 gene for enhancing the fungal virulence. Expression pattern analysis revealed that NlSPZ5 was expressed with the highest levels in the second-instar nymphs and hemolymph and could be largely activated by M. anisopliae infection. Microinjection of dsNlSPZ5 resulted in a markedly decreased survival rate and increased susceptibility to fungal infection in BPH. Notably, a transgenic strain of M. anisopliae expressing dsNlSPZ5 could effectively suppress the target gene expression and promote fungal proliferation in BPH upon fungal challenge. Compared to the wild-type strain, the transgenic fungal strain exhibited significantly enhanced insecticidal efficacy against BPH without compromising mycelial growth and sporulation. Our results demonstrate that fungal entomopathogens used as a delivery vector to express dsRNAs targeting insect immune defense-associated genes can effectively augment their virulence to the host insect, providing clues to develop novel pest management strategies through the combination of RNAi-based biotechnology and entomopathogen-based biocontrol. Full article