Search Results (198)

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

Rice (Oryza sativa) production faces serious threats from multiple biotic stresses, particularly the brown planthopper, rice blast, and bacterial blight. Developing resistant cultivars is the most sustainable control strategy. Compared to race-specific resistance genes, disrupting susceptibility genes often confers broader and potentially more durable resistance. However, engineering broad-spectrum resistance against both insect pests and pathogens by editing susceptibility genes remains challenging. In this study, we employed multiplex CRISPR/Cas9 editing to simultaneously disrupt key susceptibility genes involved in distinct defense pathways: ACS2 (for brown planthopper), Bsr-D1, ERF922 or Pi21 (for fungal blast), and Xa5 (for bacterial blight). Three triple-mutant lines (abx, aex, and apx) were successfully generated, and all exhibited significantly enhanced resistance to brown planthopper, blast, and bacterial blight without compromising major agronomic traits compared to the wild type. Our work demonstrates the feasibility of multiplex susceptibility gene editing as a precise and efficient strategy for breeding rice varieties with synchronized, broad-spectrum resistance to both insect pests and pathogenic diseases. 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

Laodelphax striatellus is one of the most destructive rice pests. However, the functions of TARs in rice pests remain largely unknown. Here, we cloned LsTAR1 from L. striatellus. LsTAR1 shares considerable sequence identity with its orthologous receptors, and clusters closely with its corresponding receptor groups. LsTAR1 was most highly expressed in the egg stage and brain of L. striatellus. Knockdown of LsTAR1 by RNA interference (RNAi) prolonged the preoviposition and oviposition period, and reduced the fecundity. Furthermore, LsTAR1 knockdown significantly decreased the mRNA levels of vitellogenin (LsVg) in the fat body and ovary, and increased the transcript levels of Vg receptor (LsVgR) in the ovary, as well as altered the expression levels of genes related to juvenile hormone (JH) and 20-hydroxyecdysone (20E) pathway. Additionally, LsTAR1 knockdown markedly reduced the honeydew excretion of the adults and affected the expression of neuropeptide signaling genes involved in insect feeding. Notably, disruption of LsTAR1 signaling via RNAi or an antagonist reduced the survival rates of L. striatellus. This study uncovers the crucial roles of LsTAR1 in reproduction, feeding, and survival in L. striatellus, and highlights its potential as a promising target for developing novel pest management strategies. Full article

Rice is a key food crop worldwide, but its yield and quality are severely constrained by insect pests. As environmental and regulatory restrictions on chemical pesticides grow, developing insect-resistant rice varieties has become a sustainable way to protect food security. This review covers recent progress in functional genomics and molecular marker mapping related to insect resistance in rice. We highlight the identification, cloning, and functional analysis of resistance genes targeting major pests, including the brown planthopper, rice gall midge, white-backed planthopper, small brown planthopper, and rice leaf roller. Several important resistance genes (such as Bph14, Bph3, and Bph29) have been cloned, and their roles in rice immunity have been clarified—covering insect feeding signal recognition, activation of salicylic acid and jasmonic acid pathways, and regulation of MAPK cascades, calcium signaling, and reactive oxygen species production. We also discuss how molecular marker-assisted selection, gene pyramiding, and transgenic techniques are used in modern rice breeding. Finally, we address future challenges and opportunities, stressing the importance of utilizing wild rice germplasm, understanding insect effector–plant immune interactions, and applying molecular design breeding to create long-lasting insect-resistant rice varieties that can withstand changing pest pressures and climate conditions. 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

The Rural Development Administration (RDA) of the Republic of Korea, in collaboration with International Rice Research Institute (IRRI), developed six temperate japonica rice varieties—MS11, Japonica 1, 2, 6, 7, and Cordillera 4—which were officially approved for release in tropical environments. These varieties offer improved eating quality, enhanced lodging resistance, and increased market value. Although initial evaluations indicated that the varieties were resistant to moderately resistant to major biotic stresses, recent field trials revealed a gradual increase in susceptibility over time. To address this, we conducted comprehensive evaluations of these varieties against rice blast under both greenhouse and field conditions and assessed their responses to bacterial leaf blight (BLB), rice tungro spherical virus (RTSV), and brown planthopper (BPH) under controlled environments. Additionally, whole-genome sequencing was employed to confirm the presence of known resistance alleles. Our findings revealed variable resistance profiles across the six varieties. Japonica 1 exhibited the most stable resistance to blast, supported by the presence of the Pi5 allele. Japonica 7 showed strong resistance to key BLB isolates and moderate resistance to a broader range of Xoo races, supported by the resistant Xa25/OsSWEET13 haplotype. In addition, Japonica 7, along with Japonica 6, carried the tsv1 gene for RTSV resistance. However, none of the six varieties possessed other major resistance genes for BPH. These results highlight the urgent need to introgress durable resistance genes into tropical japonica rice to enhance resilience and broaden the spectrum of biotic stress resistance—critical traits for sustainable rice production in tropical environments. Full article

The small brown planthopper (SBPH), Laodelphax striatellus, transmits rice stripe virus (RSV), a devastating pathogen that causes significant yield losses in rice. The components of the gut microbiota in SBPH and the effects of RSV infection on gut microorganisms are unclear. In this study, high-throughput sequencing of 16S rRNA was utilized to evaluate the composition of gut microorganisms in SBPH. The gut microbiota of SBPH was primarily composed of Proteobacteria, Firmicutes and Bacteroidetes at ratios of 94.79%, 3.04% and 1.39%, respectively; furthermore, the composition of bacteria in the gut microbiota was relatively conserved with differences at the genus level. To elucidate the response of the SBPH gut microbiota to RSV infection, we compared its composition and abundance in viruliferous and naïve SBPH. Interestingly, RSV infection was associated with increased diversity in the SBPH gut microbiota. Comparative analysis demonstrated that RSV infection elevated the relative abundance of Proteobacteria while reducing that of Firmicutes. Population counts demonstrated that RSV infection reduced the gut loads of Stenotrophomonas, Brevundimonas, and Brevibacillus, whereas the gut load of Staphylococcus was significantly increased. Further functional predictive assays revealed that RSV infection enhanced the functions of the SBPH gut microbiota in terms of metabolism, cellular processes, genetic and environmental information processing, and organismal systems. Our results indicate that RSV reshapes the composition, abundance, and functions of the SBPH gut microbiota, offering insights into virus–host–microbiome interactions. 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

This study investigated the effects of different water management practices on the growth, yield, and grain quality of rice grown under environmentally friendly farming methods in Apgok-Ri, Gungnyu-Myeon, Uiryeong-Gun, from 2022 to 2024. Treatments included mid-season drainage for 2, 3, or 4 weeks (2MD, 3MD, 4MD), followed by either low-level water management (MD-1) or alternate wetting and drying (MD-2), with continuous flooding (CF) as the control. The rice variety was machine-transplanted on 9–10 June, and organic fertilizer (90 kg N/ha) was applied as a basal dressing. Water treatments were initiated in mid-July each year. The highest yield was consistently recorded in the 2MD-2 treatment, with 5.85, 5.74, and 5.38 tons/ha from 2022 to 2024, representing 15.0%, 14.5%, and 7.8% increases over CF, respectively. On average, alternate irrigation (MD-2) resulted in higher yields than low-level water management (MD-1) by 1.19–5.90%. Grain quality was also highest in 2MD-2, showing the greatest percentage of ripened grains each year, whereas CF had the highest proportion of immature and unripe grains. Crude protein content in brown rice was lowest in 3MD-2 (6.12%), followed by 2MD-2 (7.51%). Incidences of major diseases such as sheath blight, rice blast, panicle blight, and bacterial grain blight were highest in the CF treatment. Rice leaf blight was not significantly different in 2022, but was most prevalent in CF in 2023 and 2024. There were no major differences in brown planthopper and false smut incidence, although false smut peaked in CF in 2024. These findings suggest that 2-week mid-season drainage followed by alternate irrigation (2MD-2) is an effective strategy to improve yield, grain quality, and disease resistance in sustainable rice farming systems. Full article

Defensins are a class of small cysteine-rich cationic antimicrobial peptides (AMPs) that play vital roles in immune-regulating insect–microbe interaction, offering great potential for developing pest control approaches using RNA interference (RNAi) and insect pathogens. However, the biocontrol potential of defensins from the destructive rice pest Nilaparvata lugens (brown planthopper, BPH) remains largely unexplored. Here, we identified and functionally characterized a defensin-encoding gene NldefB in BPH. The open reading frame (ORF) of NldefB is 315 bp in length, encoding 104 amino acids with a conserved Knot1 domain. The qRT-PCR results showed that the transcription level of NldefB went upward with the increasing developmental stages, with the highest expressions in the female adults and their fat body. The expression of NldefB was continuously induced by bacterial pathogens but exhibited a pattern of initial increase followed by a decrease when challenged by a fungal pathogen Metarhizium anisopliae. RNAi-mediated silencing of NldefB significantly decreased the host survival rate, egg production and hatchability, as well as the capability to resist fungal infection. Additionally, NldefB suppression resulted in a significant increase in microbial loads. Our findings underscored that NldefB plays essential roles in regulating host development, pathogen defense, and microbial maintenance, providing a potential target for RNAi- and microbe-mediated BPH biocontrol. Full article