Major Pest Of Rice Research Articles

Prealighting and Postalighting Volatile Organic Compounds Emitted by Rice Influence the Behavior of Scirpophaga incertulas.

Yellow stem borer (YSB), Scirpophaga incertulas, is a major rice pest causing significant yield losses worldwide. We investigated how volatile organic compounds (VOCs) released by the rice variety TN1, both before and after infestation, as well as by its companion weeds, Echinochloa colona and Echinochloa crus-galli, influence the behavior of YSB in host selection, recognition, and establishment. Olfactometry bioassays showed that uninfested TN1 plant VOCs attracted YSB more than those from YSB-infested rice plants and weeds. Changes in the VOC profile of TN1 during 24-48 h post-YSB infestation revealed that these postalighting compounds may deter YSB oviposition. Xylene, cymene, 1,2,3,4-tetrahydro naphthalene, dodecanol, and tetradecanol could be possible YSB attractants based on metabolomics, olfactometry, and GC-EAD studies. This work illuminates rice plant-YSB chemical interactions and VOCs dynamic function in attraction and defense processes. These findings provide a foundation for developing VOC-based pest management strategies to mitigate yield losses in rice farming.

A generalizable and interpretable model for early warning of pest-induced crop diseases using environmental data

Pest infestations and resulting crop diseases threaten global food security. Traditional pest and disease monitoring methods are time-consuming and prone to delays, thus necessitating the development of effective prediction strategies that facilitate early and timely detection. In response to this challenge, this research proposes a generalizable and interpretable machine learning model to predict two major rice pests—Green Leafhopper and Yellow Stem Borer—and a No Pest class using environmental data collected from various regions in India. The dataset, comprising factors such as temperature, humidity, and rainfall, underwent rigorous preprocessing. Key features like temperature difference, humidity difference, and vapor pressure deficit were engineered to enhance the model’s performance. Twelve baseline models were trained and their performance was evaluated using F1 scores and AUC values due to the imbalanced nature of the dataset. Through statistical analysis of baseline models, Random Forest, Balanced Random Forest, XGBoost, and CatBoost models, were selected for hyperparameter tuning via Optuna. The tuned CatBoost model demonstrated superior performance, achieving AUC values of 0.99 for Green Leafhoppers, 0.98 for Yellow Stem Borers, 1.00 for No Pest class and an overall F1 score of 0.9414 with a mean AUC value of 0.9912 across all classes. Additionally, Explainable Artificial Intelligence techniques, particularly SHAP, were employed to interpret the model’s predictions, identifying the relative importance of environmental factors in pest occurrence. This interpretability aligns the model’s predictions with established agronomic knowledge, enhancing its practical utility for early pest and disease detection. The generalizability of the proposed model suggests it can be adapted to other crops and regions, offering a valuable tool for early warning systems in agriculture, promoting sustainable practices, and reducing crop losses due to pests and diseases.

Predicting possible distribution of rice leaf roller (Cnaphalocrocis medinalis) under climate change scenarios using MaxEnt model in China

The relationship between climate conditions and pest life is a key determinant of their distribution. Cnaphalocrocis medinalis Guenee, a major rice pest, exhibits outbreaks and its distribution patterns closely linked to meteorological factors. By using 244 actual distribution and occurrence data of C. medinalis along with 8 bioclimatic data, and employing the MaxEnt model and ArcGIS, combined with the latest SSPs climate scenario data, this study evaluated the risk region distribution status in the current period and predicted changes in China from 2040 to 2100. The results indicate that an overall increase in the risk area for C. medinalis, particularly under SSP245 scenario during 2040–2060. While Low-risk areas are expected to decrease, Medium and High-risk areas are projected to increase significantly, with worsening pest infestations anticipated in southern Hubei, eastern Hunan, most of Jiangxi, central Fujian, northern Guangdong, and southern Jiangsu. Regions such as central Liaoning are expected to reach the minimum survival standard for C. medinalis in future, leading to the northward shift in risk areas. Difference plots highlighted areas of increased and decreased suitability, providing actionable insights for policymakers. Regions with increased suitability align with the predicted northward shift of many agricultural pests, necessitating enhanced monitoring, specific pest control measures, and updated agricultural policies to address changing risk profiles. Additionally, the centroid analysis showed a northwest shift direction in future, primarily located at the junction of Shaoyang City and Loudi City, situated around 27–28 °N degrees north latitude and 111–113 °E. The study underscores the significant impact of climate change on the distribution of rice leaf roller, providing valuable insights for agricultural planning and management. The northward and westward expansion of risk areas necessitates adaptive strategies to mitigate potential impacts on agriculture. Enhanced monitoring, integrated pest management, and the development of pest-resistant crops are essential for addressing future challenges posed by climate change.

Damage associated with the african rice gall midge (AFRGM), Orseolia oryzivora Harris and Gagne (Diptera : Cecidomyiidae) in an integrated cropping system at Bama, Western Burkina Faso

Orseolia oryzivora is a major insect pest of rice in Burkina Faso. This study aimed at assessing the incidence of this pest on an integrated irrigated rice cropping system in Bama, western Burkina Faso. The work was carried out during two consecutive wet cropping seasons, 2020 and 2021. The experiment was conducted using a randomized split-plot design in a latice design. The main plots (MP) were divided into secondary plots, made up of a combination of two factors: two rice varieties (FKR64 and Orylux6) and four types of crop management before rice (Mucuna, cowpea forage, organic matter and a no-crop control); the third factor, mineral fertilization (F0, F1, F2, F3) was distributed in secondary plots (SP). Weekly entomological assessments were carried out from day 28 after transplanting (DAT) to DAT 84. Symptoms of O. oryzivora damage were assessed during the vegetative and reproductive phases of rice and examined in the laboratory. Results showed that all rice varieties were infested with O. oryzivora. The higher amount of NPK, the higher the damage caused by the insect pest. The FKR64 variety recorded the highest average rate of pre-imaginal O. oryzivora populations. The results of this study could contribute effectively to the sustainable management of O. oryzivora in Bama.

Oebalus pugnax (Hemiptera: Pentatomidae) resistance to lambda-cyhalothrin in Texas and efficacy of 2 alternative insecticides in grain sorghum.

Along the Coastal Bend of Texas, the rice stink bug, Oebalus pugnax (F.), is a major pest of grain sorghum and rice that is primarily managed by insecticide applications. Reports of rice stink bug resistance to pyrethroids in Texas first surfaced in 2015 and continued to spread. To determine the status of pyrethroid resistance, rice stink bug populations across Texas and Louisiana were evaluated from 2021 to 2023. Mortality was assessed through glass vial exposures to eight concentrations (0, 0.03, 0.1, 0.3, 1, 3, 10, and 30 μg/vial) of a pyrethroid, lambda-cyhalothrin. The concentration of lambda-cyhalothrin required to kill 50% (LC50) of each population was estimated by probit analysis. Furthermore, the efficacy of insecticides, including lambda-cyhalothrin, dimethoate, and dinotefuran, were evaluated in field experiments conducted in 2021. Our results indicated that 14 of the 21 rice stink bug populations sampled were resistant to lambda-cyhalothrin, with LC50 values ranging from 42 to 1,600 times higher than a susceptible population. In the field trial, lambda-cyhalothrin did not control rice stink bugs. Dinotefuran provided excellent control of nymphs, but dimethoate provided greater control of adult rice stink bugs. To our knowledge, this is the first study to thoroughly evaluate the extent or geographic range of pyrethroid resistance in Texas for rice stink bugs.

Interaction of Predatory Ladybird Beetle, Micraspis discolor with Nilaparvata lugens throughout Paddy Growing Seasons

Coccinellidae is a high-interest family that has performed well and is widely distributed. It is valuable in economic service because it acts as an agricultural biological control agent. The Micraspis discolor (Syn=Verania) (Coleoptera: Coccinellidae) is a successful omnivorous predator in rice ecosystem and functions well as a general biological control for maintaining the population of brown planthopper (BPH) (Nilaparvata lugens), the major rice pest worldwide. Studies of natural enemies’ abundance are necessary to increase the practical use of biological control in agriculture. This study investigated the abundance correlation of M. discolor (prey) and rice pest N. lugens (prey) from two different geographical areas of rice fields in west and south Peninsular Malaysia. The cyclone lightrap and sweep net method succeeded in collecting 185 individuals of M. discolor and N. lugens. The study indicated that M. discolor, and the N. lugens collected from Selangor were more numerous than Johor in the ripening phase than in the reproductive and vegetative phases. M. discolor can be found in all stages of rice growth. There are positive correlations between M. discolor and N. lugens in both localities throughout the rice growing season. The positive correlation highlighted that the number of pests has increased parallel to the number of predators and vice versa. The use of M. discolor as a predator is essential in agriculture, along with the treatment of a healthy ecosystem landscape of diverse vegetation combinations, which helps to reduce the use of pesticides.

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.

Periodic colonization of Trichogramma japonicum for bio-control of yellow stem borer (Scirpophaga incertulas) in summer low-land rice (Oryza sativa)

Yellow stem borer [Scirpophaga incertulas (Walker)], is a major pest of low-land rice (Oryza sativa L.), causing 30–40% yield losses. The use of biological control agents to suppress yellow stem borer (YSB) population and damage across Asia includes inundative releases of the egg parasitoid, Trichogramma japonicum Ashmead. However, information on the time and number of parasitoids’ releases are lacking to control YSB in summer low-land rice. Therefore, an experiment was conducted during summer seasons of 2018 and 2019 at ICAR-National Institute of Biotic Stress Management, Raipur, Chhattisgarh to standardize the time and number of T. japonicum releases for effective biocontrol of YSB. Experiment consisted of 3 different treatment schedules, viz. T1, Four releases of T. japonicum at weekly intervals on the 7th, 14th, 21st, 28th days after planting (DAT); T2, Four releases of T. japonicum at weekly intervals on the 14th, 21st, 28th, 35th DAT; T3, Four releases of T. japonicum at weekly intervals on the 21st, 28th, 35th, 42nd DAT; and T4, Control (no release of wasps). Significant reduction of YSB-induced damage symptoms was observed in the treatment schedule (T2) consisting of four releases of T. japonicum (@50,000 wasps/ha/release) at weekly intervals on the 14th, 21st, 28th, 35th DAT of rice which significantly reduced the dead heart (9.1%, 45.83% reduction over control) and the white ear (1.8%, 47.05% reduction over control), as compared to untreated control plots (T4) (16.8% dead heart, 3.4% white ear) in summer 2018. Similarly, in summer 2019, the reduction in dead heart and white ear by the treatment (T2) was 43.35% and 46.15% over control, respectively. The significant reduction of YSB-induced damages corresponded with the increased grain yield in (T2) from 2018–19 i.e. 12.74–20.18% across the seasons. The results suggest that the (T2) augmentative releases provided ecologically viable bio-control of YSB during the summer seasons in low-land rice.

The G932C mutation of chitin synthase 1 gene (CHS1) mediates buprofezin resistance as confirmed by CRISPR/Cas9-mediated knock-in approach in the brown planthopper, Nilaparvata lugens

The brown planthopper (Nilaparvata lugens) is a major destructive rice pest in Asia. High levels of insecticide resistance have been frequently reported, and the G932C mutation in the chitin synthase 1 (CHS1) gene has been found to mediate buprofezin resistance. However, there has been no direct evidence to confirm the functional significance of the single G932C substitution mutation leading to buprofezin resistance in N. lugens. Here, we successfully constructed a knock-in homozygous strain (Nl-G932C) of N. lugens using CRISPR/Cas9 coupled with homology-directed repair (HDR). Compared with the background strain susceptible to buprofezin (Nl-SS), the knock-in strain (Nl-G932C) showed a 94.9-fold resistance to buprofezin. Furthermore, resistant strains (Nl-932C) isolated from the field exhibited a 2078.8-fold resistance to buprofezin, indicating that there are other mechanisms contributing to buprofezin resistance in the field. Inheritance analysis showed that the resistance trait is incomplete dominance. In addition, the Nl-G932C strain had a relative fitness of 0.33 with a substantially decreased survival rate, emergence rate, and fecundity. This study provided in vivo functional evidence for the causality of G932C substitution mutation of CHS1 with buprofezin resistance and valuable information for facilitating the development of resistance management strategies in N. lugens. This is the first example of using CRISPR/Cas9 gene-editing technology in a hemipteran insect to directly confirm the role of a candidate target site mutation in insecticide resistance.

Multiomics-assisted characterization of rice-Yellow Stem Borer interaction provides genomic and mechanistic insights into stem borer resistance in rice.

By deploying a multi-omics approach, we unraveled the mechanisms that might help rice to combat Yellow Stem Borer infestation, thus providing insights and scope for developing YSB resistant rice varieties. Yellow Stem Borer (YSB), Scirpophaga incertulas (Walker) (Lepidoptera: Crambidae), is a major pest of rice, that can lead to 20-60% loss in rice production. Effective management of YSB infestation is challenged by the non-availability of adequate sources of resistance and poor understanding of resistance mechanisms, thus necessitating studies for generating resources to breed YSB resistant rice and to understand rice-YSB interaction. In this study, by using bulk-segregant analysis in combination with next-generation sequencing, Quantitative Trait Loci (QTL) intervals in five rice chromosomes were mapped that could be associated with YSB resistance at the vegetative phase in a resistant rice line named SM92. Further, multiple SNP markers that showed significant association with YSB resistance in rice chromosomes 1, 5, 10, and 12 were developed. RNA-sequencing of the susceptible and resistant lines revealedseveral genes present in the candidate QTL intervals to be differentially regulated upon YSB infestation. Comparative transcriptome analysis revealed a putative candidate gene that was predicted to encode an alpha-amylase inhibitor. Analysis of the transcriptome and metabolite profiles further revealed a possible link between phenylpropanoid metabolism and YSB resistance. Taken together, our study provides deeper insights into rice-YSB interaction and enhances the understanding of YSB resistance mechanism. Importantly, a promising breeding line and markers for YSB resistance have been developed that can potentially aid in marker-assisted breeding of YSB resistance among elite rice cultivars.

Bio-Efficacy of Newer Insecticides on Major Insect Pests of Rice (Oryza sativa L.)

Present study was carried out at the Farm of Institute of Agricultural Sciences, Banaras Hindu University, Varanasi during 2022-23. In order to study the bio-efficacy of insecticides; field experiment was laid with six treatments viz., chlorantraniliprole 0.53%G @ 29.81 g a.i/ha,chlorantraniliprole 0.53%G@39.75g a.i/ha, chlorantraniliprole 0.53%G@49.69 g a.i/ha, chlorantraniliprole 0.4G@ 40 g a.i/ha and fipronil 0.3G @75 g a.i/ha including the untreated control. In case of stem borer and leaf folder chlorantraniliprole 0.53%GR @39.75g a.i/haprovided significantly better control followed by chlorantraniliprole 0.53% GR @ 49.69g a.i/ha, Fipronil 0.30% GR@ 75g a.i/hachlorantraniliprole 0.53%G @ 29.81 g a.i/ha and Chlorantraniliprole 0.40% GR@ 49.69g a.i/ha. It was concluded that the Bio-efficacy of insecticidal treatments against major pests of paddy showed that chlorantraniliprole 0.53%G 39.5g a.i/ha was first best insecticidal treatment against both Lepidopteran insect pests of paddy.

Knockdown of MAPK p38-linked genes increases the susceptibility of Chilo suppressalis larvae to various transgenic Bt rice lines

Bacillus thuringiensis (Bt) toxins have provided exceptional control of agricultural insect pests, however, over reliance on the proteins would potentially contribute to the development of field tolerance. Developing new sustainable insect pest control methods that target the mechanisms underlying Bt tolerance can potentially support the Bt control paradigm while also providing insights into basic insect physiology. The MAPK p38 pathway is strongly associated with Bt tolerance in Chilo suppressalis, a major pest of rice. To gain insights into how this pathway impacts tolerance, high-throughput screening of C. suppressalis larval midguts initially identified eight novel target genes. Increased larval sensitivity to the transgenic cry1Ca rice strain T1C-19 was observed following RNA interference-mediated knockdown of four of the genes, Cscnc, Csgcp, Cszfp26 and CsZMYM1. Similar enhanced sensitivity to the TT51 (expressing Cry1Ab/1Ac) and T2A-1 (expressing Cry2Aa) transgenic rice lines occurred when Cszfp26 and CsZMYM1 were knocked down. All four target genes are downstream of the MAPK p38 pathway but do not participate in negative feedback loop of the pathway. These results implicate Cscnc, Csgcp, Cszfp and CsZMYM1 in the C. suppressalis transgenic cry1Ca rice tolerance mechanism regulated by MAPK p38. These findings further enhance our understanding of the MAPK p38-dependent molecular mechanisms underlying Bt tolerance in C. suppressalis and open new avenues of tolerance management to develop.

Field Screening of Genotypes for Resistance to Major Rice Pests

Preliminary screening studies against rice stem borer and leaf folder were conducted at Regional Agricultural Research Station, Pattambi during kharif 2016 and rabi 2016-17 involving 14 rice cultures and susceptible check TN 1. The promising rice genotypes were evaluated under All India Coordinated Research Project on Rice (AICRPR) Hyderabad during kharif 2017, 2018 and 2019 under Stem borer screening trial, Leaf folder screening trial and multiple pest resistance screening trial. The rice culture KAUPTB 0627-2-11 (Cul 06-1) offered resistance to stem borer (both dead hearts and white ears). Cultures JS1,3,5 and 7 showed tolerance to both Stem borer and Leaf folder while Cul M9 exhibited field tolerance to multiple pests like Stem borer, mixed population of planthoppers and leaf folder

Life Cycle of Chilo zacconius Blensynski (Lepidoptera: Crambidae) on Artificial Diet in The Laboratory

The African striped stemborer Chilo zacconius (Blensynski) is a major pest of rice in Nigeria. The life cycle of the African striped stemborer C. zacconius was assessed under laboratory conditions. The egg incubation period was 5.08 ± 0.19 days. while the mean duration of the I,II, III, IV, V instars were 4.97 ± 0.14, 6.73 ± 0.28, 8.13 ± 0.38,9.00 ± 0.46, 8.00 ± 0.31 days respectively. Pupal duration was observed in 6.00 ± 0.19 days while the average emergence of the adult was 3.42 ± 0.15 days. Fecundity rate of the striped stem borer ranged from 80-150 eggs. The adult life span of the stem borer ranged between 3 to 4 days while the total life cycle is completed within 40 to 65 days. The morphometrics of all stages were also recorded accordingly. Additional research is still required to determine the optimal artificial diet for the mass rearing of C. zacconius, as this will enhance the development of tailored strategies to mitigate its harm while fostering the sustainability of rice farming

Nanoparticle-delivered RNAi-based pesticide target screening for the rice pest white-backed planthopper and risk assessment for a natural predator

Vacuolar-type (H+)-ATPase (vATPase) is a conserved multi-subunit eukaryotic enzyme composed of 14 subunits that form a functional complex consisting of an ATP-hydrolytic domain (V1) and a proton-translocation domain (V0). ATP hydrolysis and subsequent H+ translocation rely heavily on a fully assembled V1/V0 complex. Since vATPase is crucial for insect survival, it is a viable molecular target for pest control. However, detailed functional analyses of the 14 subunits and their suitability for pest control have not been fully explored in a single insect species. In this study, we identified 22 vATPase subunit transcripts that correspond to 13 subunits (A1, A2, B, C, D, E, F, G, H, a1, a2, c and d) in the white-backed planthopper (WBPH), Sogatella furcifera, a major hemipteran pest of rice. RNAi screens using microinjection and spray-based methods revealed that the SfVHA-F, SfVHA-a2 and SfVHA-c2 subunits are critical. Furthermore, star polymer (SPc) nanoparticles were utilized to conduct spray-induced and nanoparticle-delivered gene silencing (SI-NDGS) to evaluate the pest control efficacy of RNAi targeting the SfVHA-F, SfVHA-a2 and SfVHA-c2 transcripts. Target mRNA levels and vATPase enzymatic activity were both reduced. Honeydew excreta was likewise reduced in WBPH treated with dsRNAs targeting SfVHA-F, SfVHA-a2 and SfVHA-c2. To assess the environmental safety of the nanoparticle-wrapped dsRNAs, Cyrtorhinus lividipennis Reuter, a major natural enemy of planthoppers, was also sprayed with dsRNAs targeting SfVHA-F, SfVHA-a2 and SfVHA-c2. Post-spray effects of dsSfVHA-a2 and dsSfVHA-c2 on C. lividipennis were innocuous. This study identifies SfVHA-a2 and SfVHA-c2 as promising targets for biorational control of WBPH and lays the foundation for developing environment-friendly RNAi biopesticides.

INFLUENCE OF WHITE PEPPER POWDER (Piper nigrum L.) VEGETABLE INSECTICIDE ON PEST MORTALITY OF RICE WEEVILS

A reduction in rice quality may result from pest infestations in storage facilities. In addition to being a major pest of rice, the rice weevil (Sitophilus oryzae L.) is a problem in warehouses. Attacks by rice weevils may result in lower-quality rice. Using white pepper powder as a pesticide is one way to solve this issue. The purpose of this study is to ascertain how white pepper powder, a botanical pesticide, affects rice weevil pest mortality, as well as the optimal dosage and mode of administration. In this study, there were six treatments and four replications in a single factor totally randomized design. The rate at which rice weevil bugs died and the percentage of rice weight loss were the study's parameters. The results showed that the death of rice weevil pests was influenced using white pepper powder. The highest mortality rate was L5 at 52.5%, which is the best dose.

Synergism of Cry1Ca toxicity by gut resident Enterococcus spp. in the rice stem borer, Chilo suppressalis

The bacterium Bacillus thuringiensis (Bt) is the most economically successful biopesticide to date, and Bt insecticidal proteins are produced in transgenic crops for pest control. However, relevant details in the Bt-mediated killing process remain undefined. In our previous research, we observed reduced larval susceptibility to Bt Cry1Ca in Chilo suppressalis, a major rice pest in China, after gut microbiota elimination. Here, we tested the hypothesis that gut microbiota, particularly abundant Enterococcus spp., influences C. suppressalis susceptibility to Cry1Ca. We isolated and identified four Enterococcus spp. from C. suppressalis gut microbiota and evaluated their impact on Cry1Ca toxicity. Among the four Enterococcus spp. identified, three of them (E. casseliflavus, E. faecalis, and E. mundtii) dramatically increased larval mortality when introduced in axenic C. suppressalis challenged with Cry1Ca. Gut epithelial damage by Cry1Ca promoted the translocation of Enterococcus spp. from the gut lumen into the hemocoel, where they proliferated and induced larval melanization and hemocyte apoptosis. Our combined findings demonstrate that the presence of specific gut microbiota can greatly affect susceptibility to Cry1Ca through melanization and apoptosis of hemocytes. Better understanding of the Bt intoxication process guides the development of bio-enhancers for Bt-based microbial biopesticides and potential improvement of transgenic crops.

Functional analysis of Ornithine decarboxylase in manipulating the wing dimorphism in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

The brown planthopper (BPH, Nilaparvata lugens), a major insect pest of rice, can make a shift in wing dimorphism to adapt to complex external environments. Our previous study showed that NlODC (Ornithine decarboxylase in N. lugens) was involved in wing dimorphism of the brown planthopper. Here, further experiments were conducted to reveal possible molecular mechanism of NlODC in manipulating the wing dimorphism. We found that the long-winged rate (LWR) of BPH was significantly reduced after RNAi of NlODC or injection of DFMO (D, L-α-Difluoromethylornithine), and LWR of males and females significantly decreased by 21.7% and 34.6%, respectively. Meanwhile, we also examined the contents of three polyamines under DFMO treatment and found that the contents of putrescine and spermidine were significantly lower compared to the control. After 3rd instar nymphs were injected with putrescine and spermidine, LWR was increased significantly in both cases, and putrescine was a little bit more effective, with 5.6% increase in males and 11.4% in females. Three days after injection of dsNlODC, injection of putrescine and spermidine rescued LWR to the normal levels. In the regulation of wing differentiation in BPH, NlODC mutually antagonistic to NlAkt may act through other signaling pathways rather than the classical insulin signaling pathway. This study illuminated a physiological function of an ODC gene involved in wing differentiation in insects, which could be a potential target for pest control.

Demography and fitness of Sesamia inferens Walker (Lepidoptera: Noctuidae) on three important gramineous crops

BackgroundPink stem borer, Sesamia inferens (Walker), a major rice pest, has rarely been reported to cause serious damage to sorghum in China. During a survey of insect pests in glutinous sorghum for Chinese liquor production areas in Guizhou Province, it was found that S. inferens has caused serious damage to local sorghum in recent years.MethodsIn this context, we assessed the adaptation of S. inferens to three gramineous crop host plants (maize, rice and sorghum) based on age-stage, two-sex life table theory.ResultsSesamia inferens had the highest development time, survival rate and total longevity on rice, followed by on sorghum and maize. There was no significant difference in intrinsic rate of increase and finite rate of increase among maize (r = 0.0702 day−1, λ = 1.0727 day−1), sorghum (r = 0.0681 day−1, λ = 1.0705 day−1) and rice (r = 0.0645 day−1, λ = 1.0666 day−1), but the mean generation period (T) was significantly higher for populations reared on rice (53.84 days) than on sorghum (49.53 days) and maize (47.31 days).ConclusionsThe results of our study indicate that S. inferens was able to complete the full developmental cycle on all three host plants. This study further supports that glutinous sorghum is an adaptable host plant for S. inferens.

Climate change and the future distribution of Brown Planthopper in Indonesia: A projection study

The Brown planthopper, Nilapavarta lugens (Stål) (BPH) is a major pest of rice after the adoption of the Green Revolution. Its outbreaks are frequently linked to climate variability and change, posing almost all rice varieties in Indonesia at risk, resulting in economic losses due to reduced production. The amount of information available about its current and future potential distribution as well as the influencing factors are still limited.The objective of this study is to examine the impact of climate variability on BPH and to assess the projection of the BPH potential distribution under different climate scenarios. Maximum entropy (MaxEnt) was applied to predict the current and future potential distribution of BPH over Indonesia. This study used data on BPH-affected areas, rainfall and temperature, andthe Ocean Nino Index (ONI) on a monthly interval to examine the linkage between climate and BPH affected areas. The global-climate models from phase 6 of coupled model intercomparison project (CMIP6) for period 2041–2060 were used to examine the variations in 19bioclimatic variables for two shared socioeconomic pathways (SSPs) compared to baseline period (1971–2000). The findings concluded that the dynamics of BPH damaged areas were strongly influenced by higher temperature and rainfall in dry season associated with La Niña events. Precipitation of driest month, precipitation seasonality, mean temperature of driest quarter and temperature seasonality were the most affected factors in the distribution of BPH. Our results highlight BPH distribution was expected to increase to 2.4% and 3.02% (moderately suitable), 1.88% and 1.95% (suitable), 2.59% and 2.76% (highly suitable) respectively under SSP2-4.5 and SSP5–8.5. These findings could serve as early warnings to adjust agricultural practices and implement tailored pest management methods to effectively address the shifting pattern of BPH in the future.