Rice Leaf Folder Cnaphalocrocis Medinalis Research Articles

Knockdown of the glucosamine-6-phosphate N-acetyltransferase gene by RNA interference enhances the virulence of entomopathogenic fungi against rice leaffolder Cnaphalocrocis medinalis

Insect cuticle acts as a first line of defense and a physical protective barrier against entomopathogens. Chitin biosynthesis pathway plays a crucial role in chitin formation in the cuticle of insects. Glucosamine-6-phosphate N-acetyltransferase (GNA) is a key enzyme in insect chitin biosynthesis that regulate the chitin formation. However, how GNA-mediated cuticle metabolism influences virulence of entomopathogenic fungi is still unknown. In this study, CmGNA gene was cloned and characterized from the rice leaffolder Cnaphalocrocis medinalis. The CmGNA contains an open read frame (ORF) 600 nucleotides, encoding 199 amino acids with an isoelectric point of 8.65 and a molecular weight of 22.30 kDa. The expression profile showed that CmGNA was highly expressed in 4th instar larvae and in the cuticle. Here, we also reported the impact of CmGNA gene and entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, on expression pattern of chitin biosynthesis genes, feeding behavior, survival rate and average body weight of infected larvae, phenotypic deformities, rate of pupation, and adult emergence. Our results showed that knockdown of CmGNA and application of M. anisopliae and B. bassiana three days after RNA interference (RNAi) significantly decreased the expression of CmGNA and other associated genes, reduced feeding efficiency and survival rate, and caused loss of average body weight, less rate of pupation and adult emergence of infected larvae. Knockdown of CmGNA gene also increased the lethality of larvae caused by M. anisopliae and B. bassiana and resulted in significantly phenotypic deformities of infected larvae. Our findings illustrated that RNAi-mediated CmGNA knockdown disturbed the chitin synthesis genes that led to enhancing the virulence of M. anisopliae and B. bassiana, which can provide us new insights to develop novel biocontrol strategies against C. medinalis.

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.

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.

Efficacy of Chlorantraniliprole in Combination with Lambdacyhalothrin (Ampligo 150 ZC) Against the Leaf Folder, Cnaphalocrocis medinalis (Guenee) in Rice Field

Rice is a cereal grain and a member of the grass family (Poaceae). One of the challenges faced by rice farmers is the infestation of pests, including the leaf folder (Cnaphalocrocis medinalis). A field experiment was conducted to assess the bio-efficacy of Chlorantraniliprole 9.3 + Lambda cyhalothrin 4.6 ZC against the rice leaf folder Cnaphalocrocis medinalis during the kharif season of 2020 and rabi season of 2021. The treatments included Chlorantraniliprole 9.3 + Lambda cyhalothrin 4.6 ZC at rates of 150, 200, and 250 ml per ha, Chlorantraniliprole 18.5 SC at 150 ml per ha, Lambda cyhalothrin 4.9 CS at 250 ml per ha, and Fipronil 5 SC at 1500 ml per ha. Analysis of pooled data revealed that all treatments were effective in controlling leaf folder damage, leading to a significant increase in yield. Among the tested chemicals, Chlorantraniliprole 9.3 + Lambda cyhalothrin 4.6 ZC at 250 and 200 ml per ha exhibited the highest reduction in leaf folder population, followed by Chlorantraniliprole 9.3 + Lambda cyhalothrin 4.6 ZC at 150 ml per ha and Chlorantraniliprole 18.5 SC at 150 ml per ha.

Bioefficacy Studies on Insecticidal Activities of Sargassum wightii with Neem oil against rice Leaf Folder, Cnaphalocrocis medinalis

The experiment was conducted to evaluate the insecticidal activity of solvent extracts of brown algal seaweed, Sargassum wightii and its combination with neem oil against rice leaf folder Cnaphalocrocis medinalis in the Department of Entomology, Faculty of Agriculture, Annamalai University, Tamil Nadu, India during 2022-2023. Seaweed extracts at 6, 7 and 8% concentrations alone and its combination with neem oil @ 0.5 and 1% concentrations were tested against rice leaf folder and compared to neem oil @ 1% as standard check. The combination treatment seaweed extract @ 8% + neem oil @ 1% resulted in the highest larval mortality of 80.00 percent. In seaweed extract @ 8% + neem oil @ 1%, the larva to adult conversion ratio was 1: 0.06 whereas in the untreated control, the ratio was 1:1.

Population Dynamics of the Rice Leaf Folder <i>Cnaphalocrocis medinalis</i> Guenee: A Lifetable Study

The rice leaf folder Cnaphalocrocis medinalis Guenee has become a major concern, causing outbreaks in various parts of India. A lifetable study was conducted to analyze the growth, survival, reproduction, and mortality of C. medinalis, aiming to determine the weakest lifestages and unravel its population dynamics. The study observed the highest survival rate at the fourth-instar larval stage and the lowest during the egg and first-instar larval stages. A population trend index of 5.9 was observed, indicating significant population growth.

Study on Impact of Sowing Dates on Rice Leaf Folder Cnaphalocrocis medinalis (Guenee) in Direct Seeded Rice

A field experiment to study the impact of sowing dates on Rice leaf folder in direct seeded rice was conducted at Agricultural College Farm, Bapatla during kharif, 2021. Early planted rice crop had lower pest than later transplanted rice. Various dates have a significant impact on the occurrence of biotic stress, particularly insect pests. To identify suitable plating dates to minimize the leaf folder infestation in paddy the following experiment was conducted. Sowing was done at four different dates with 10 days interval which were taken as treatments each replicated with five times and the data has also been correlated with light trap data. The mean per cent damage ranged from 9.44 to 16.64 %. Highest infestation (16.64 %) was observed in last date of sowing and least damage (9.44 %) was observed in first date of sowing. Correlation analysis of light trap catch data shown a positive correlation with morning (r = 0.373) and evening (r = 0.186) relative humidity while a negative correlation with maximum (r = - 0.182), and minimum (r = - 0.017) temperatures and rainfall (r= - 0.154). Multiple Linear Regression (MLR) of trapped adult number and climatic conditions at different sowing dates revealed that weather parameters contributed to the variation in moth number trapped in light trap by 35.4 per cent in first date of sowing, 42.2 per cent in second date of sowing, 59.6 per cent in third date of sowing, and 50.7 per cent in fourth date of sowing. Yield ranged from 3632 kg ha-1 in last date of sowing to 5156 kg ha-1 in first date of sowing.

Pathogenicity of Beauveria bassiana (Balsamo) Vuillemin Isolate (TNAU ENT BB1) Against Rice Leaf Folder, Cnaphalocrocis medinalis (Guenee) in In-vitro (Laboratory) Conditions

Rice productivity is impaired by sucking, leaf feeding and borer insect pests. Among the leaf feeders, rice leaf folder Cnaphalocrocis medinalis (Guenee) cause significant yield loss. The non-chemical insect pest management is gaining momentum among farmers, and biocontrol management is one of the essential components. The efficacy of entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin isolate against C. medinalis was studied using the laboratory culture maintained in rice leaves. Different concentrations of B. bassiana were applied topically on the second instar C. medinalis larvae. The mortality observations were recorded at 48 hrs intervals from the third day and continued up to 11 days. The highest mortality of 78.33% was observed at concentration 1×108 conidia/ml, and the lowest mortality of 36.67% was observed at concentration 1×103 conidia/ml. The determined median lethal concentration (LC50) of B. bassiana (Balsamo) Vuillemin isolate against C. medinalis is 5.44 x 105 conidia/ml.

Glucose Dehydrogenases-Mediated Acclimation of an Important Rice Pest to Global Warming.

Global warming is posing a threat to animals. As a large group of widely distributed poikilothermal animals, insects are liable to heat stress. How insects deal with heat stress is worth highlighting. Acclimation may improve the heat tolerance of insects, but the underlying mechanism remains vague. In this study, the high temperature of 39 °C was used to select the third instar larvae of the rice leaf folder Cnaphalocrocis medinalis, an important insect pest of rice, for successive generations to establish the heat-acclimated strain (HA39). The molecular mechanism of heat acclimation was explored using this strain. The HA39 larvae showed stronger tolerance to 43 °C than the unacclimated strain (HA27) persistently reared at 27 °C. The HA39 larvae upregulated a glucose dehydrogenase gene, CmGMC10, to decrease the reactive oxygen species (ROS) level and increase the survival rate under heat stress. The HA39 larvae maintained a higher activity of antioxidases than the HA27 when confronted with an exogenous oxidant. Heat acclimation decreased the H2O2 level in larvae under heat stress which was associated with the upregulation of CmGMC10. The rice leaf folder larvae may acclimate to global warming via upregulating CmGMC10 to increase the activity of antioxidases and alleviate the oxidative damage of heat stress.

Understanding the Biochemical Basis of Resistance in Rice to Leaffolder (Cnaphalocrocis medinalis)

Rice leaf folder has been recorded to cause major loss in rice yield. To know the relevance of biochemical factors in conferring tolerance to rice leaffolder Cnaphalocrocis medinalis, a study was conducted utilizing 196 rice accessions at Pandit Jawaharlal Nehru College of Agriculture and Research Institute, Karaikal. Standard evaluation system developed by IRRI for leaf folder complex was followed for screening the rice accessions and entries were ranked accordingly based on the leaf damage. Among these entries, top five entries along with the susceptible check (TN1) were selected for analysis of biochemical factors such as total chlorophyll, total sugars, reducing sugars, total phenols, total soluble protein and proline. Results revealed that high level of total phenols, moderate chlorophyll content, and low sugar content in leaves conferred resistance to this pest in rice.

Gut bacterial communities and their assembly processing in Cnaphalocrocis medinalis from different geographic sources.

The insect gut harbors numerous microorganisms that may have functions in development and reproduction, digestion, immunity and protection, and detoxification. Recently, the influence factors on gut microbiota were evaluated in the rice leaffolder Cnaphalocrocis medinalis, a widespread insect pest in paddy fields. However, the relationship between gut microbiota composition and geography is poorly understood in C. medinalis. To reveal the patterns of C. medinalis gut bacterial communities across geographic sources and the ecological processes driving the patterns, C. medinalis were sampled from six geographic sources in China, Thailand, and Vietnam in 2016, followed by gut bacterial 16S ribosomal RNA gene sequencing. A total of 22 bacterial phyla, 56 classes, 84 orders, 138 families, 228 genera, and 299 species were generated in C. medinalis from six geographic sources. All alpha diversity indices differed among the samples from different geographic sources. Analysis of similarity (ANOSIM) and permutational multivariate analysis of variance (PERMANOVA) both revealed significant differences in the gut microbiota of C. medinalis from six geographic sources. A total of 94 different taxa were screened as indicators for the gut microbiota of C. medinalis from six geographic sources by linear discriminant analysis effect size (LEfSe). The gene ontology (GO) pathways of the gut microbiota in C. medinalis differed among geographic sources. In total, the bacterial communities within geographic sources were mainly determined by stochastic processes, and those between geographic sources were mainly determined by deterministic processes. This study elucidates that geography plays a crucial role in shaping the gut microbiota of C. medinalis. Thus, it enriches our knowledge of gut bacteria in C. medinalis and sheds light on the mechanisms underlying C. medinalis gut microbial shifts across geography.

Damage of brown planthopper (BPH) Nilaparvata lugens and rice leaf folder (LF) Cnaphalocrocis medinalis in parent plants lead to distinct resistance in ratoon rice

ABSTRACT Herbivore-induced defense responses are often specific, whereas plants could induce distinct defense responses corresponding to infestation by different herbivorous insects. Brown plant hopper (BPH) Nilaparvata lugens, a phloem-feeding insect, and rice leaf folder (LF) Cnaphalocrocis medinalis, a chewing insect, are both specialist herbivores on rice. To characterize the distinct resistance primed by prior damage to these two specialist herbivores, we challenged rice plants with two herbivores during vegetative growth of parent plants and assessed plant resistance in subsequent ratoons. Here, we show that LF and BPH induce different suites of defense responses in parent rice plants, LF induced higher level of JA accumulation and OsAOS, OsCOI1 transcripts, while BPH induced higher accumulation of SA and OsPAL1 transcripts. Moreover, an apparent loss of LF resistance was observed in OsAOS, OsCOI1 RNAi lines. Ratoon plants generated from parents receiving prior LF infestation exhibited higher jasmonic acid (JA) levels and elevated levels of transcripts of defense-related genes associated with JA signaling, while ratoon generated from parents receiving prior BPH infestation exhibited higher salicylic acid (SA) levels and elevated levels of transcripts of defense-related genes associated with SA signaling. Moreover, previous LF infestation obviously elevated ratoons resistance to LF, while previous infestation by BPH led to enhanced resistance in ratoons to BPH. Pre-priming of ratoons defense to LF was significantly reduced in OsAOS and OsCOI1 RNAi plant, but silencing OsAOS and OsCOI1 did not attenuate ratoons resistance to BPH. These results suggest that infestation of two specialist herbivores with different feeding styles in parent crop led to distinct defense responses in subsequent rations, and the acquired resistance to LF in ratoons is associated with priming of jasmonic acid-dependent defense responses.

Efficacy of Takumi 20% WG against Rice Stem Borers and Leaf Folder

Insect pests pose major menace to the rice production and amongst these stem borer Scirpophaga incertulas (Walker) and rice leaf folder Cnaphalocrocis medinalis (Guen.) are important and cause enormous yield losses. This study evaluates the efficacy of newer insecticide, Takumi 20WG (flubendiamide 20%) against these, compared with checks, Fame 480SC (flubendiamide 39.35%) and Coragen 18.5SC (chlorantraniliprole 18.5%). The insecticides were applied on economic threshold basis (ETL) for stem borers (2% deadhearts on basmati and 5% deadhearts on non-basmati) and/or leaf folders (10% damaged leaves) in randomized block design. The results revealed that Takumi 20WG @ 125 g/ ha was statistically at par with the checks, Fame 480SC and Coragen 18.5SC but significantly superior to its lower dosages of 100 and 75 g/ ha.

Data from Heat stress drives a separate pattern between female and male moths of the rice leaf folder Cnaphalocrocis medinalis

Data from Heat stress drives a separate pattern between female and male moths of the rice leaf folder Cnaphalocrocis medinalis

Effects of Host Plant and Insect Generation on Shaping of the Gut Microbiota in the Rice Leaffolder, Cnaphalocrocis medinalis.

Gut microbes in insects may play an important role in the digestion, immunity and protection, detoxification of toxins, development, and reproduction. The rice leaffolder Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Crambidae) is a notorious insect pest that can damage rice, maize, and other gramineous plants. To determine the effects of host plants and generations on the gut microbiota of C. medinalis, we deciphered the bacterial configuration of this insect pest fed rice or maize for three generations by Illumina MiSeq technology. A total of 16 bacterial phyla, 34 classes, 50 orders, 101 families, 158 genera, and 44 species were identified in C. medinalis fed rice or maize for three generations. Host plants, insect generation, and their interaction did not influence the alpha diversity indices of the gut microbiota of C. medinalis. The dominant bacterial taxa were Proteobacteria and Firmicutes at the phylum level and Enterococcus and unclassified Enterobacteriaceae at the genus level. A number of twenty genera coexisted in the guts of C. medinalis fed rice or maize for three generations, and their relative abundances occupied more than 90% of the gut microbiota of C. medinalis. A number of two genera were stably found in the gut of rice-feeding C. medinalis but unstably found in the gut microbiota of maize-feeding C. medinalis, and seven genera were stably found in the gut of maize-feeding C. medinalis but unstably found in the gut of rice-feeding C. medinalis. In addition, many kinds of microbes were found in some but not all samples of the gut of C. medinalis fed on a particular host plant. PerMANOVA indicated that the gut bacteria of C. medinalis could be significantly affected by the host plant and host plant × generation. We identified 47 taxa as the biomarkers for the gut microbiota of C. medinalis fed different host plants by LEfSe. Functional prediction suggested that the most dominant role of the gut microbiota in C. medinalis is metabolism, followed by environmental information processing, cellular processes, and genetic information processing. Our findings will enrich the understanding of gut bacteria in C. medinalis and reveal the differences in gut microbiota in C. medinalis fed on different host plants for three generations.

Identification and Characterization of a Double-Stranded RNA Degrading Nuclease Influencing RNAi Efficiency in the Rice Leaf Folder Cnaphalocrocis medinalis.

Rice leaf folder Cnaphalocrocis medinalis is one of the most serious pests of rice in rice-planting regions worldwide. DsRNA-degrading nucleases (dsRNases) are important factors in reducing the efficiency of RNA interference (RNAi) in different insects. In this study, a dsRNase gene from C. medinalis (CmdsRNase) was cloned and characterized. The CmdsRNase cDNA was 1395 bp in length, encoding 464 amino acids. The CmdsRNase zymoprotein contains a signal peptide and an endonuclease NS domain that comprises six active sites, three substrate-binding sites, and one Mg2+-binding site. The mature CmdsRNase forms a homodimer with a total of 16 α-helices and 20 β-pleated sheets. Homology and phylogenetic analyses revealed that CmdsRNase is closely related to dsRNase2 in Ostrinia nubilalis. Expression pattern analysis by droplet digital PCR indicated that the expression levels of CmdsRNase varied throughout the developmental stages of C. medinalis and in different adult tissues, with the highest expression levels in the fourth-instar larvae and the hemolymph. CmdsRNase can degrade dsRNA to reduce the efficiency of RNAi in C. medinalis. Co-silencing of CmCHS (chitin synthase from C. medinalis) and CmdsRNase affected significantly the growth and development of C. medinalis and thus improved RNAi efficacy, which increased by 27.17%. These findings will be helpful for green control of C. medinalis and other lepidopteran pests by RNAi.

Effects of Date of Transplanting on The Incidence of Rice Leaf Folder Cnaphalocrocis medinalis (Guenée) and its Population Dynamics

Field studies were conducted to evaluate the impact of transplanting dates and weather parameters on the incidence of rice leaf folder Cnaphalocrocis medinalis (Guenee). During 2018 kharif season, the first incidence was noticed during 27th standard meteorological week (SMW) irrespective of the transplanting dates, with peak being in the 28th SMW (1.67% damaged leaves/hill). Least damage was observed in 4th date of transplanting (20th July), while maximum incidence was with 20th June transplanting. The correlation of incidence with temperature showed negative correlation, while rainfall and relative humidity showe positive relationship.

Silicon Plays an Effective Role in Integrated Pest Management against Rice Leaffolder Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae)

Silicon Plays an Effective Role in Integrated Pest Management against Rice Leaffolder Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae)

Field screening of popular rice cultivars against rice leaf folder (Cnaphalocrosis Medinalis Gunee.) incidence in north eastern coastal plains of Odisha

Studies on the reaction of popular rice cultivars against rice leaf folder Cnaphalocrocis medinalis (Guenee) and various aspects of morphological characters of popular rice cultivars of coastal plains of Odisha together was conducted for kharif 2015-16 and 2016-17 at farmers field and Krishi Vigyan Kendra Research unit. It is one of the most serious pest in rice production. It is expensive and environmentally unsafe to manage this serious pest by using chemicals. Best approach to manage this pest is to develop host-plant resistance. Ten popular rice genotypes were screened for resistance to rice leaf folder. Varietal preference of rice leaf folder among ten popular rice varieties was analysed during kharif 2015 and 2016 at 30, 45, 60 and 75 DAT and the per cent of leaf folder damage, the varieties were given ratings according to Standard Evaluation System (IRRI)’s for rice (scale of 0-9). All the ten varieties come under two different ratings i.e., nine varieties under a rating of 3 (Moderately resistance) and one varieties under a rating of 5 (moderately susceptible). The lowest damage was recorded in PRATIKSHYA(ORS-201-5) (14.9%) followed by Pooja (15.7%), Anjana(15.9%),which was on par with Surendra (16.1),CR-1018(16.7%),CR-1009(16.7%) and MTU-1001(16.9%).The highest damage was observed in MTU-7029 (31.00%) followed by SWARNA SUB -1 (29.03%).The correlation coefficient (r) values between Morphological characters and per cent leaf damage by the rice leaf folder during 2015-2016 kharif and 2016-17 indicated that the length of the leaf did not affect the infestation of rice leaf folder significantly, but all the other factors showed significant correlation with leaf folder infestation, whereas positive significant correlation was observed with leaf width.

Comparative transcriptome analysis of the rice leaf folder (Cnaphalocrocis medinalis) to heat acclimation

BackgroundThe rice leaf folder Cnaphalocrocis medinalis Güenée is a serious insect pest of rice in Asia. This pest occurs in summer, and it is sensitive to high temperature. However, the larvae exhibit heat acclimation/adaptation. To understand the underlying mechanisms, we established a heat-acclimated strain via multigenerational selection at 39 °C. After heat shock at 41 °C for 1 h, the transcriptomes of the heat-acclimated (S-39) and unacclimated (S-27) larvae were sequenced, using the unacclimated larvae without exposure to 41 °C as the control.ResultsFive generations of selection at 39 °C led larvae to acclimate to this heat stress. Exposure to 41 °C induced 1160 differentially expressed genes (DEGs) between the heat-acclimated and unacclimated larvae. Both the heat-acclimated and unacclimated larvae responded to heat stress via upregulating genes related to sensory organ development and structural constituent of eye lens, whereas the unacclimated larvae also upregulated genes related to structural constituent of cuticle. Compared to unacclimated larvae, heat-acclimated larvae downregulated oxidoreductase activity-related genes when encountering heat shock. Both the acclimated and unacclimated larvae adjusted the longevity regulating, protein processing in endoplasmic reticulum, antigen processing and presentation, MAPK and estrogen signaling pathway to responsed to heat stress. Additionally, the unacclimated larvae also adjusted the spliceosome pathway, whereas the heat-acclimated larvae adjusted the biosynthesis of unsaturated fatty acids pathway when encountering heat stress. Although the heat-acclimated and unacclimated larvae upregulated expression of heat shock protein genes under heat stress including HSP70, HSP27 and CRYAB, their biosynthesis, metabolism and detoxification-related genes expressed differentially.ConclusionsThe rice leaf folder larvae could acclimate to a high temperature via multigenerational heat selection. The heat-acclimated larvae induced more DEGs to response to heat shock than the unacclimated larvae. The changes in transcript level of genes were related to heat acclimation of larvae, especially these genes in sensory organ development, structural constituent of eye lens, and oxidoreductase activity. The DEGs between heat-acclimated and unacclimated larvae after heat shock were enriched in the biosynthesis and metabolism pathways. These results are helpful to understand the molecular mechanism underlying heat acclimation of insects.