Leaf Folder Research Articles

Assessing Different Rice Genotypes Tolerance against the Major Pests and Identifying the Biochemical Basis of Tolerance

A total of 196 rice genotypes were screened for tolerance against paddy stem borer and leaf folder pests under open field conditions. Damage assessment followed the standard evaluation procedure for rice developed by IRRI (1988). Stem borer incidence was recorded during both the vegetative and reproductive stages while leaf folder incidence was recorded at five different growth stages (30, 40, 50, 60, and 70 days after transplanting). Interestingly, tolerance to paddy stem borer varied among the genotypes. Genotypes resistant at the Vegetative Stage did not show tolerance at the Reproductive Stage. Consequently, leaf folder infestation was recorded at five different growth stages, demonstrating that although the mean infestation was considered for identifying tolerance, the rate of infestation against an accession is not consistent across all growth stages. Additionally, biochemical analysis of the resistant entries, along with a susceptible check (TN1), revealed that higher total phenol concentrations, moderate chlorophyll content, and lower sugar levels were key factors contributing to pest tolerance. The correlation between infestation percentage and biochemical parameters showed a high positive correlation between total sugars and infestation percentage and a strong negative correlation between total phenols and infestation percentage, indicating that phenols play a role in plant defense.

Detection of Rice Leaf Folder in Paddy Fields Based on Unmanned Aerial Vehicle-Based Hyperspectral Images

Pest infestations significantly impact rice production and threaten food security. Remote sensing offers a vital tool for the non-destructive, rapid detection of rice pests. Existing studies often focus on laboratory conditions at the leaf level, limiting their applicability for precise pesticide application. Therefore, this study aimed to develop a method for detecting rice pests (rice leaf folders) in paddy fields based on unmanned aerial vehicle (UAV) hyperspectral data. Firstly, a UAV imaging system collected hyperspectral images of rice plants in both the jointing and heading stages. A total of 222 field plots for investigating rice leaf folders was established during these two periods. Secondly, 23 vegetation indices were calculated as candidates for identifying rice pests. Then, hyperspectral data and field investigation data from the jointing stage were used to construct a machine learning (extreme gradient boosting, XGBoost) algorithm for detecting rice pests. The results showed that the XGBoost model exhibited the best performance when eight vegetation indices were considered as the selected input features for model construction: the Red-edge Normalized Difference Vegetation Index (red-edge NDVI), Structure Insensitive Pigment Index (SIPI), Enhanced Vegetation Index (EVI), Atmospherically Resistant Vegetation Index (ARVI), Soil-Adjusted Vegetation Index (SAVI), Red-edge Chlorophyll Index (CIred-edge), Pigment-Specific Simple Ratio680 (PSSR680), and Carotenoid Reflectance Index700 (CPI700). The training and testing accuracies reached 87.46% and 86%, respectively. Furthermore, the heading stage application confirmed the model’s feasibility. Thus, the XGBoost model with input features of eight vegetation indices provides an effective and reliable method for detecting rice leaf folders, supporting real-time, precise pesticide use in rice cultivation.

Identification and functional study of Fib-L, a major silk fibroin gene component in rice leaf folders.

The rice leaf folder, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), is a major migratory pest in rice agriculture. This pest is characterised by its larvae's ability to fold rice leaves using silk, a behaviour that culminates in the formation of a silken cocoon during the pupal stage. The fibroin light chain (CmFib-L) gene is crucial for silk production, yet its specific function in C. medinalis has reminded elusive. This study presents a comprehensive analysis of the CmFib-L gene, revealing its complete open reading frame (ORF) and expression patterns. Notably, the gene is highly expressed in the fifth-instar larvae and the silk gland, which are critical stages for silk production. Our experiments demonstrate that silencing the CmFib-L gene leads to a reduction in pupal weight, an extension of the pupal stage and a disorganised silk cocoon. Furthermore, the larval behaviour of leaf folding and spinning is significantly impaired when the expression of CmFib-L is downregulated. These findings not only show the importance of fibroin light chain in silk production but also reveal a new target gene to regulate and control the behaviour and development of C. medinalis.

Revealing pest patterns: A comparative spatial distribution analysis of insect threats in Kharif rice across the key agricultural regions in the Eastern India.

This study investigates the spatial distribution and aggregation patterns of major insect pests in Kharif rice fields during the 2023 growing season in Eastern India. The analysis focuses on key pests such as yellow stem borer (YSB), gall midge, green leaf hopper (GLH), and brown planthopper (BPH), as well as rice thrips, caseworm, whorl maggot, Gundhi bug, grasshopper, and leaf folder. Using statistical indices, this study aims to understand pest behavior across Standard Meteorological Weeks (SMWs) to better inform pest control strategies. The study reveals significant clustering and aggregation patterns among the pests. YSB exhibited variance-mean ratio (VMR) values between 1.14 (40th SMW) and 1.96 (31st SMW), with dispersion parameter (K) values ranging from 0.57 to 21.65, and a peak index of dispersion of 132.66 (43rd SMW). Similarly, gall midge showed VMR values from 6.19 to 10.48, whereas GLH and BPH recorded VMR ranges of 1.19 to 132.10 and 1.01 to 1.50, respectively. These spatial distribution trends were confirmed through values for Iwao's patchiness index and Taylor's power law, indicating strong pest aggregation in specific areas. The results underscore the need for region-specific integrated pest management strategies that take into account pest clustering and environmental factors influencing pest distribution. Although an S-curve pattern of infestation-showing gradual population increases, rapid peaks, and eventual decline-was observed, the primary focus remains spatial patterns, which are critical for optimizing pest management and improving rice crop sustainability in the region. © 2024 Society of Chemical Industry.

Retraction: Optimized Scorpion Polypeptide LMX: A Pest Control Protein Effective against Rice Leaf Folder.

Retraction: Optimized Scorpion Polypeptide LMX: A Pest Control Protein Effective against Rice Leaf Folder.

Efficacy of Insecticides Against Yellow Stem Borer (Scirpophaga incertulas Walker) and Rice Leaf Folder (Cnaphaocrocis medinalis Guenee) and Their Impact on Natural Enemies in Rice Ecosystem

The experiment was conducted at AAU-Assam Rice Research Institute, Titabor to test the efficacy of some insecticides against yellow stem borer and rice leaf folder. Out of 8 tested insecticides, Chlorantraniliprole 18.5 SC showed the best result in minimizing yellow stem borer and rice leaf folder infestation. The lowest infestation percentage of yellow stem borer (2.10%) was observed on Chlorantraniliprole 18.5 SC treated plots followed by treatment with Chlorantraniliprole 10% + Lambda Cyhalothrin 5% ZC (2.33 %) at 7 DAT. Similarly, white ear head (0.33%) was also recorded as the lowest on Chlorantraniliprole 18.5 SC treated plots. Chlorantraniliprole 18.5 SC recorded the lowest infestation percentage of rice leaf folder at 7 DAT (3.40 %) and 14 DAT (3.53 %) followed by Chlorantraniliprole 10% + Lambda Cyhalothrin 5% ZC. While, the highest number of spiders and coccinellids were recorded in Chlorantraniliprole 0.4GR (2.43 spider/plant and 1.33 coccinellids/plant) followed by Thiamethoxam 25WG (2.13 spiders/plant and 1.10 coccinellids/plant). In terms of yield, Chlorantraniliprole 18.5 SC was found to be the best insecticide which provided the highest yield of 5.83t/ha among all the tested insecticides.

Seasonal incidence of rice leaf folder Cnaphalocrocis medinalis (Guenee) in rice at Kanpur Uttar Pradesh

Seasonal incidence of rice leaf folder Cnaphalocrocis medinalis (Guenee) in rice at Kanpur Uttar Pradesh

Understanding the Impact: Insect Pests of Millets and their Consequences on Yield Loss

Millets, crucial cereal crops in many regions, face significant threats from various insect pests, leading to substantial yield losses. Insect pests such as stem borers, leaf folders, aphids, midges, bugs, caterpillars, and termites inflict damage at different growth stages of millet plants. Stem borers like Chilo partellus and Sesamia inferens bore into stems, impairing structural integrity, while leaf folders such as Cnaphalocrocis medinalis create folded leaf shelters for feeding, causing extensive tissue damage. Aphids such as Rhopalosiphum maidis and shoot bugs like Peregrinus maidis extract sap, resulting in wilting and stunting of plants. Millet midges like Geromyia penniseti and Stenodiplosis sorghicola target reproductive structures, leading to grain abortion and reduced yield. Earhead pests like Cryptoblabes gnidiella and Helicoverpa armigera feed on developing grains, causing significant losses in quality and quantity. Additionally, termites like Odontotermes spp. and Microtermes spp. damage roots and stems, disrupting nutrient and water uptake causing plant death. Understanding the biology and ecology and implementing appropriate pest management strategies are crucial for mitigating yield losses and ensuring millet production sustainability.

Efficacy of Various Insecticides against Leaf Folder Cnaphalocrocis medinalis (Guenee) in Rice and the Calculation of the Benefit-cost Ratio

The present investigation was conducted at Heera Puri research field, Institute of Agriculture and Natural Sciences, Deen Dayal Upadhyaya Gorakhpur University, Gorakhpur during Kharif, 2023. The relative effectiveness of six insecticides viz., Flubendiamide 39.35 % SC, Chlorpyriphos 20 EC, Acephate 95 SC, Chlorantraniliprole 18.5 SC, Fipronil 5 SC, Cartap hydrochloride 50% SP and Control. The study revealed that the treatment Flubendiamide 39.35% SC was found most effective followed by Chlorantraniliprole 18.5 SC, and Fipronil 5 SC whereas the highest infestation was recorded in the control plot. The significantly higher grain yield was obtained in Flubendiamide 39.35% SC treated plots which are followed by Chlorantraniliprole 18.5 SC, Fipronil 5 SC, Cartap hydrochloride 50% SP, Acephate 95 SC and Chlorpyriphos 20 EC. The highest increase in yield over control was reported in the plot treated with Flubendiamide 39.35% SC followed by Chlorantraniliprole 18.5 SC, Fipronil 5 SC, Cartap hydrochloride 50% SP, Acephate 95 SC, and Chlorpyriphos 20 EC. The economics of various treatments based on net profit and cost of plant protection revealed that. the highest cost: benefit ratio of Chlorpyriphos 20 EC was followed by Chlorantraniliprole 18.5 SC, followed by Acephate 95 SC, Fipronil 5 SC and the lowest benefit-cost ratio was reported in plots treated with Cartap hydrochloride 50% SP.

Composition of Parasitoid Wasps in Insect Pests of Rice (Rice Leaffolder, Cnaphalocrocis Medinalis Guenée)

Biological control is one aspect of Integrated Pest Management (IPM). The method focusses on natural enemies; beneficial insects are applied for biological control of agricultural insect pests and also provide an environmentally friendly approach. For the rice pests including Rice Leaf Folder (RLF), several parasitoids tend to be natural enemies that could be used to control the pest from the egg stage to pupa. This study was conducted with two varieties of rice, namely “Sen Kra Oub” and “Sro Ngea” at Battambang Province of Cambodia. Parasitoid wasps were collected from egg to pupa stages of RLF and rice yellow stem borer by rearing method, and stored in 70% of alcohol solution before sending for identification in Vietnam’s Institute of Ecology and Biological Resources (IEBR) Laboratory. The outcomes revealed that five hymenopteran parasitic wasps of three different families were found, viz. Apanteles cypris Nixon, Bracon onukii Watanabe and Pentatermus striatus (Szepligeti) (Braconidae), Xanthopimla flavolineata Cameron (Ichneumonidae), and Telenomus rowani Gahan (Scelionidae) and being the primary parasitoids of rice leaffolder, Cnaphalocrocis medinalis Guenee; stemborer Scirpophaga incertulas Walker (Pyralidae) and black branded swift Pelopidas mathias (Hesperiidae). Parasitism was not found at the vegetative phase with Sen Kra Ob varieties but in reproductive phase. parasitism proportion was 16.66% and 28.57% to 50% in ripening phase, different from Sro Ngea variety where a proportion was found in vegetative phase 27.27%, reproductive phase at 28.57% to 40% and 28.57% to 43% in ripening phase. All the hymenopteran parasitoids were initially recorded in Cambodia, whereby all the parasitoids were potential agents for biological control for important rice insect pests. The outcome of this research suggests that the Government should invest more in the research and development for biological control in Cambodia.

Heat-stress memory enhances the acclimation of a migratory insect pest to global warming.

In the face of rising global temperatures, the mechanisms behind an organism's ability to acclimate to heat stress remain enigmatic. The rice leaf folder, Cnaphalocrocis medinalis, traditionally viewed as temperature-sensitive, paradoxically exhibits robust larval acclimation to heat stress. This study used the heat-acclimated strain HA39, developed through multigenerational exposure to 39°C during the larval stage, and the unacclimated strain HA27 reared at 27°C to unravel the transgenerational effects of heat acclimation and its regulatory mechanisms. Heat acclimation for larvae incurred a fitness cost in pupae when exposed to high temperature, yet a significant transgenerational effect surfaced, revealing heightened fitness benefit in pupae from HA39, even without additional heat exposure during larval recovery at 27°C. This transgenerational effect exhibited a short-term memory, diminishing after two recovery generations. Moreover, the effect correlated with increased superoxide dismutase (SOD) enzyme activity and expression levels of oxidoreductase genes, representing physiological and molecular foundations of heat acclimation. Heat-acclimated larvae displayed elevated DNA methylation levels, while pupae from HA39, in recovery generations, exhibited decreased methylation indicated by the upregulation of a demethylase gene and downregulation of two methyltransferase genes at high temperatures. In summary, heat acclimation induces DNA methylation, orchestrating heat-stress memory and influencing the expression levels of oxidoreductase genes and SOD activity. Heat-stress memory enhances the acclimation of the migratory insect pest to global warming.

Brachymeria swaminathani sp. nov. (Hymenoptera, Chalcididae, Brachymeriinae) a new pupal parasitoid of rice leaf folder from southern India

A new species of the megadiverse cosmopolitan chalcidid genus Brachymeria Westwood (Chalcididae, Brachymeriinae), B. swaminathani is described with illustrations based on female specimens reared from pupae of rice leaf folder Cnaphalocrocis medinalis (Guenée) from southern India.

Impact of Crop Phenology and Environmental Factors on Rice Leaf Folder Infestation in Middle Gangetic Plains of India

Impact of Crop Phenology and Environmental Factors on Rice Leaf Folder Infestation in Middle Gangetic Plains of India

Assay of Front-Line Demonstration on Integrated Pest and Disease Management (IPDM) in Rice in the Vikarabad District of Telangana, India

Rice crop is attacked by various insects and diseases in spite of using pesticides, but relaying only on synthetic pesticides usage resulted into disrupt the natural balance between crop pests and their existed natural enemies. Integrated pest and disease management (IDPM) is a concept which is blended with all possible proven technologies like Cultural, Mechanical, Biological and Chemical methods. Front line demonstration on Integrated Pest and Disease Management in rice was taken up in farmers fields during kharif season of two consecutive years of 2021 and 2022 by DAATTC, Tandur in Vikarabad district of Telangana. Study revealed that seed treatment with Carbendazim @3gm/kg seed, seedling root dip with Pseudomonas species 10gm /lit of water, application of Carbofuran granules @160g/cent nursery, installation of pheromone traps, formation of alley ways and need based application of fertilizers and pesticides reduced the pest like Stem borer, BPH, Leaf folder and Blast disease significantly compared to farmers practice. Mean higher yield was recorded in demo field 6065 kg/ha compared to 5795 kg/ha in check, and showed 4.6 per cent yield increases in demonstration fields.

Field efficacy of newer insecticides against leaf folder (Cnaphalocrocis medinalis Gn.) in rice

Field efficacy of newer insecticides against leaf folder (Cnaphalocrocis medinalis Gn.) in rice

Survey and Management of Major Insect Pests of Summer Paddy

Roving survey was conducted for the major insect pests of summer paddy in north eastern zone of Karnataka. At vegetative stage, the incidence of yellow stem borer Scirpophaga incertulas (Walker) was highest in Vijayanagar district (2.38%), whereas, the occurrence of brown planthopper Nilaparvata lugens (Stal) (1.61/hill), green leafhopper Nephotettix nigropictus (Stål) (1.66/ hill) and rice gall fly Orseolia oryzae (Wood-Mason) (6.10%) was maximum in Koppal. The incidence of rice leaf folder, Cnaphalocrocis medinalis (Guenee) (1.33%) was highest in Raichur. All the five insects pest of summer paddy surveyed were abudant in Koppal at reproductive stage. The efficacy of bioagents was evaluated. Bacillus thuringiensis (Berliner) formulations. Dipel was effective with least S. incertulas (1.93%) and C. medinalis damage (1.72%) whereas, azadirachtin and Dipel recorded the lowest S. incertulas (2.64% and 2.72%) and C. medinalis (1.67% and 1.71%), respectively. Similarly, azadirachtin and Metarhizium anisopliae recorded lowest N. lugens (1.90 hoppers/ hill) and N. nigropictus (0.70 hoppers/ hill) after three sprays at 15 days interval.

Comparative bio-efficacy of flubendiamide 20 WG against yellow stem borer, Scirpophaga incertulas Walker and leaf folder, Cnaphalocrocis medinalis Guenee, safety to natural enemies and residues in basmati rice under field conditions of semi-arid region of India

Comparative bio-efficacy of flubendiamide 20 WG against yellow stem borer, Scirpophaga incertulas Walker and leaf folder, Cnaphalocrocis medinalis Guenee, safety to natural enemies and residues in basmati rice under field conditions of semi-arid region of India

Bio-Efficacy of Different Insecticides Against Soybean Leaf Folder, Omiodes indicata (Fabricius, 1775) (Lepidoptera: Crambidae)

A study was conducted at the Agricultural Research Station (UAS, Dharwad), Sankeshwar, Karnataka during Kharif 2022-23 to assess the effectiveness of different insecticides against soybean leaf folder, Omiodes indicata. Among five treatments, lambda cyhalothrin 4.6 % + chlorantraniliprole 9.3 % ZC @ 0.4 ml l-1 exhibited the lowest mean population of soybean leaf folder, Omiodes indicata on 5th and 10th day after spray with 2.12 and 0.98 larval population per meter row length, respectively which was followed by emamectin benzoate 5 % SG @ 0.3 g l-1 (3.03 and 1.83 larvae per meter row length). Lambda cyhalothrin 4.6 % + chlorantraniliprole 9.3 % ZC was found to be the best effective treatment with 81.97 % reduction over control followed by emamectin benzoate 5 SG (71.61 %). Similar results were obtained with per cent defoliation.

Morpho-biochemical Basis of Resistance Against Cnaphalocrocis Medinalis Guenee in South Gujarat

The study aimed to investigate the morpho-biochemical basis of resistance to the rice leaf folder Cnaphalocrocis medinalis in ten rice varieties, at the Main Rice Research Centre Farm, Navsari Agricultural University, Navsari, Gujarat during kharif 2021. The width of the leaves varied among the varieties, with GNR-2, GNR-6, GNR-7, and GR-15 having the smallest leaves and TN-1 and GNR-4 having the largest. There was a significant positive correlation between leaf width and infestation. Analysis of chlorophyll, sugar, and protein content in the leaves showed that TN-1 had the highest levels at both 30 days and 50 days after transplanting (DAT), while GR-15 had the lowest. These factors were positively correlated with infestation. On the other hand, phenol content was the highest in GR-15 and lowest in TN-1, with a significant negative correlation with infestation. Chlorophyll, sugar, and protein content increased with higher infestation levels while phenol content decreased.

Rice Leaf Diseases Detection Using YOLOv8

The development of rice plants holds immense importance today as it impacts crucial aspects of life such as food security, agricultural advancement, and the economy of nations. Consequently, research on disease detection in rice plants, particularly using machine learning, is gaining popularity. Several diseases pose a threat to rice leaves, with Leaf Blast, Leaf Folder, and Brown Spot being the most common ones, directly affecting crop cultivation and causing yield loss. In this study, we propose the utilization of deep learning, the state-of-the-art image processing solution, to address this issue. Our proposed method consists of two steps: first, collecting reliable dataset by approaching and capturing direct images of rice leaf diseases in the fields, and second, designing and training an Artificial Intelligence (AI) model using the YOLOv8 algorithm to detect and classify the three aforementioned diseases. The data set used in this study includes 3175 images, divided into three parts, of which the training part is 2608 images, the validation part is 326 images and the test part is 241 images. Our experimental results demonstrate an accuracy up to 88.9% for the proposed model.