Spodoptera Litura Research Articles

Conserved Odorant Receptors Involved in Nonanal-Induced Female Attractive Behavior in Two Spodoptera Species.

Moths rely on plant volatiles to locate appropriate plants for feeding and laying eggs. While extensive research has been conducted on the global agricultural pests, Spodoptera frugiperda and Spodoptera litura, their molecular mechanisms for detecting plant volatiles remain mostly unknown. Here, we have demonstrated that nonanal, a common plant volatile, is attractive for both virgin and gravid females of the two species. Second, we have identified a conserved odorant receptor clade (SfruOR47 clade) that is primarily tuned to nonanal. Finally, by three-dimensional (3D) structure prediction, molecular docking, and site-directed mutagenesis, we have revealed that the His57 and Glu61 residues, also shared by other six orthologous ORs, are essential for nonanal binding in SfruOR47 and SlituOR9, indicating the conserved structure and function of ORs in the SfruOR47 clade. These findings offer novel insights into the molecular mechanisms and evolutionary aspects of moth behavior in response to plant volatiles.

Molecular identification and expression analysis of magnetic receptor in Spodoptera frugiperda (Lepidoptera: Noctuidae), an invasive species in China

AbstractThe fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera, Noctuidae), has emerged as a highly invasive pest globally in the past decade due to its remarkable migratory capabilities. Magnetic receptors play an important role in the migration and navigation of the animal, but little is known about the molecular mechanism of the magnetic receptors of S. frugiperda (SfMagR). In this study, we successfully cloned the cDNA encoding SfMagR, which has a 396 bp of open reading frame (ORF) encoding 132 amino acids. Phylogenetic analysis revealed a high conservation of magnetic receptors among various animal species, notably demonstrating a 98.4% sequence identity between S. frugiperda and Spodoptera litura, and a 70.3% identity with Homo sapiens, a vertebrate species. Expression analysis conducted across different developmental stages demonstrated SfMagR expression in the egg, larval, and pupal stages of the moth, but exhibited predominate expression in the adult stage, particularly in male adults. Moreover, the tissue expression profile indicated that SfMagR expression primarily occurred within the thorax of the moth, specifically in the thorax excluding the legs and wings. These findings not only provide fundamental data and a molecular foundation for future investigations into the function of SfMagR, but also offer valuable insights for the future management of invasive species.

Application of Turmeric Extract Botanical Insecticide On Feeding Activity And Mortality Of Spodoptera Litura Larvae

This research aimed to evaluate the effectiveness of turmeric extract as a botanical insecticide on the feeding activity and mortality of Spodoptera litura larvae. The method used in this study was a toxicity test using the leaf dip method. The experiment employed a completely randomized design with combinations of turmeric extract concentrations (0, 4, 8, 12, and 16 grams per liter of water) and instar types (1 and 2). The results showed that the application of turmeric extract on cabbage leaves reduced the feeding activity of instar 2 and 3 larvae. Meanwhile, the turmeric extract had an effect on the mortality of instar 2 and 3 larvae only at a concentration of 16%. The symptoms observed in the dead larvae were changes in color and body texture. The conclusion of this research is that 16% is the minimum effective concentration of turmeric extract on instar 2 and 3 S. litura larvae. This study should be continued on other instar types at the field scale.

Reconstruction of Gut Bacteria in Spodoptera frugiperda Infected by Beauveria bassiana Affects the Survival of Host Pest.

Spodoptera frugiperda (Lepidoptera: Noctuidae) is a migratory agricultural pest that is devastating on a global scale. Beauveria bassiana is a filamentous entomopathogenic fungus that has a strong pathogenic effect on Lepidoptera pests but little is known about the microbial community in the host gut and the dominant populations in fungus-infected insects. B. bassiana AJS91881 was isolated and identified from the infected larvae of Spodoptera litura. The virulence of AJS91881 to the eggs, larvae, pupae and adults of S. frugiperda was measured. Moreover, the gut microbial community diversity of healthy and fungus-infected insects was analyzed. Our results showed that after treatment with B. bassiana AJS91881, the egg hatching rate, larval survival rate and adult lifespan of the insects were significantly reduced, and the pupae rigor rate was significantly increased compared to that of the control group. Additionally, the gut microbial community was reconstructed after B. bassiana infection. At the phylum and genus level, the relative abundance of the Proteobacteria and Serratia increased significantly in the B. bassiana treatment group. The KEGG function prediction results showed that fungal infection affected insect gut metabolism, environmental information processing, genetic information processing, organism systems and cellular processes. Fungal infection was closely related to the metabolism of various substances in the insect gut. Serratia marcescens was the bacterium with the highest relative abundance after infection by B. bassiana; intestinal bacteria S. marcescens inhibited the infection of insect fungi B. bassiana against the S. frugiperda. The presence of gut bacteria also significantly reduced the virulence of the fungi against the insects when compared to the group with the larvae fed antibiotics that were infected with fungal suspension (Germfree, GF) and healthy larvae that were infected with fungal suspension prepared with an antibiotic solution (+antibiotic). In conclusion, the reconstruction of the insect intestinal bacterial community is an indispensable link for understanding the pathogenicity of B. bassiana against S. frugiperda. Most importantly, in the later stage of fungal infection, the increased abundance of S. marcescens in the insect intestine inhibited the virulence of B. bassiana to some extent. The findings aid in understanding changes in the gut microbiota during the early stages of entomopathogenic fungal infection of insects and the involvement of insect gut microbes in host defense mediated by pathogenic fungal infection. This study is also conducive to understanding the interaction between entomopathogenic fungi, hosts and gut microbes, and provides a new idea for the joint use of entomopathogenic fungi and gut bacteria to control pests.

Biocompatible nanoscale silica particles fabricated from aminopropyltriethoxysilane functionalized brick ash induced versatile pesticidal activity

The present study is aimed to evaluate pesticidal activity and biocompatibility including ecotoxicity of functionalized silica nanoparticles that synthesized by simple, in vitro, green technology principles. Sol-gel method was adopted for the synthesis of silica nanoparticles and was functionalized by Aminopropyltriethoxysilane (APS), characterized and confirmed the uniform, monodispersive, highly stable particles with the size range of 10–200 nm. The synthesized Nano silica was screened against the developmental stages of Spodoptera litura. Pesticidal study revealed that the functionalized nanoparticles were effective against all the life stages of the insect by recording high mortality and the drastic reduction in the larval, pupae, adult emergence, and adult longevity stages. The ecotoxic effect of synthesized nano-silica was tested on soil parameters, growth parameters of Arachis hypogaea, and compatibility with Trichoderma viride. This study revealed there was no toxic effect on soil, growth parameters of Arachis hypogaea, and most significantly the growth of Trichoderma viride was not inhibited. A biocompatibility study was done by using Zebrafish and Rabbit model. The study divulges there was no toxic effect on all the developmental stages of the Embryo. Further, the nanoparticles did not exhibit any dermatotoxicological effect which confirmed no signs and symptoms of inflammation. Nano-silica emerges as a promising eco-friendly and non-toxic substitute for conventional insecticides. Its utilization has the potential to augment both environmental preservation and economic prosperity on a national scale. Furthermore, the integration of silica-based nanoparticles with biocidal agents demonstrates notable biocompatibility and the capacity to hinder bacterial adhesion.

Synergistic and additive interactions of Shewanella sp., Pseudomonas sp. and Thauera sp. with chlorantraniliprole and emamectin benzoate for controlling Spodoptera litura (Fabricius)

The imprudent use of insecticides causes the development of resistance in insect pest populations, contamination of the environment, biological imbalance and human intoxication. The use of microbial pathogens combined with insecticides has been proposed as an alternative strategy for insect pest management. This IPM approach may offer effective ways to control pests, in addition to lowering the risk of chemical residues in the environment. Spodoptera litura (Fabricius) is a major pest of many crops like cotton, maize, tobacco, cauliflower, cabbage, and fodder crops globally. Here, we evaluated the combined effects of new chemistry insecticides (chlorantraniliprole and emamectin benzoate) and entomopathogenic bacterial strains, Shewanella sp. (SS4), Thauera sp. (M9) and Pseudomonas sp. (EN4) against S. litura larvae inducing additive and synergistic interactions under laboratory conditions. Both insecticides produced higher larval mortality when applied in combination with bacterial isolates having maximum mortality of 98 and 96% with LC50 of chlorantraniliprole and emamectin benzoate in combination with LC50 of Pseudomonas sp. (EN4) respectively. The lower concentration (LC20) of both insecticides also induced synergism when combined with the above bacterial isolates providing a valuable approach for the management of insect pests. The genotoxic effect of both the insecticides was also evaluated by conducting comet assays. The insecticide treatments induced significant DNA damage in larval hemocytes that further increased in combination treatments. Our results indicated that combined treatments could be a successful approach for managing S. litura while reducing the inappropriate overuse of insecticides.

Beyond Molecular Recognition: A Perylene Bisimide Derivative as a Functional Mimic of Chlorpyrifos.

Supramolecular assemblies of perylene bisimide derivative (PBI-SAH) have been developed which show 'turn-on' detection of chlorpyrifos in aqueous media, apple residue and blood serum. Differently from the already reported fluorescent probes for the detection of CPF, PBI-SAH assemblies also show affinity for acetylcholinesterase (AChE) which endow the PBI-SAH molecules with mixed inhibitory potential to restrict the AChE catalysed hydrolysis of acetylthiocholine (ATCh) in MG-63 cell lines (in vitro) and in mice (in vivo). The molecular docking studies support the inhibitory activity of PBI-SAH assemblies and their potential to act as safe insecticide with high benefit to harm ratio. The insecticidal potential of PBI-SAH derivative has been examined against Spodoptera litura (S. litura) and these studies demonstrate its excellent insecticidal activity (100 % mortality in nineteen days). To the best of our knowledge, this is the first report regarding development of PBI-SAH assemblies which not only detect chlorpyrifos but also mimic AChE inhibitory activity of CPF to show promising aptitude as safe insecticide.

Growth Inhibitory Activity of <i>Annona squamosa</i> against Polyphagous Pest <i>Spodoptera litura</i> (F)

The present study was conducted to evaluate the insect growth inhibitory effect of seed extract of the medicinal plant, Annona squamosa L. against Spodoptera litura F., under laboratory conditions. The four solvent seed extracts of A. squamosa namely, methanol, ethyl acetate, hexane and chloroform at 0.5, 1, 1.5, 2 and 2.5% concentrations were tested against third instar larvae of S. litura. The results showed that, among the four solvent extracts, methanol solvent extracts of A. squamosa at 2% and 2.5% concentration was found to be effective. It has been observed that methanol extract at 2.5% resulted in 97.5% mortality with no malformations in the developmental stages. The result indicated that the response of larval mortality and deformities in the developmental stages was dose dependent.

Role of the epsilon glutathione S-transferases in xanthotoxin tolerance in Spodoptera litura

Spodoptera litura, a polyphagous lepidopteran pest, demonstrates a remarkable capacity to adapt to varying host plants by efficiently detoxifying phytochemicals. However, the underlying mechanism for this adaptation is not well understood. Herein, twenty eplison glutathione S-transferase genes (GSTes) were characterized and their roles in phytochemical tolerance were analyzed in S. litura. Most of the GSTe genes were mainly expressed in the larval midgut and fat body. Exposure to the phytochemicals, especially xanthotoxin, induced the expression of most GSTe genes. Molecular docking analysis revealed that xanthotoxin could form stable bonds with six xanthotoxin-responsive GSTes, with binding free energies ranging from −36.44 to −68.83 kcal mol−1. Knockdown of these six GSTe genes increased the larval susceptibility to xanthotoxin. Furthermore, xanthotoxin exposure significantly upregulated the expression of two transcription factor genes CncC and MafK. Silencing of either CncC or MafK reduced the expression of GSTe16, which exhibited the largest change in response to xanthotoxin. Additionally, analysis of the promoter sequence of GSTe16 revealed the presence of seven CncC/Maf binding sites. Luciferase reporter assays showed that CncC and MafK enhanced the expression of GSTe16, leading to the increased xanthotoxin tolerance in S. litura. These findings provide insight into the functions and transcriptional regulatory mechanisms of GSTes, thereby enhancing our understanding of the role of GSTs in the adaptation of lepidopteran pests to phytochemicals.

Influence of age, diurnal cycle, and plant and non-plant surfaces on oviposition by Spodoptera litura (Fabricius)(Lepidoptera: Noctuidae)

Influence of age, diurnal cycle, and plant and non-plant surfaces on oviposition by Spodoptera litura (Fabricius)(Lepidoptera: Noctuidae)

Functional characterization of SlGSTD3 and SlGSTD4 associated with phoxim and chlorpyrifos resistance in Spodoptera litura

Glutathione S-transferases (GSTs) is one of the main detoxification enzyme systems in insects and play important roles in insecticide resistance by direct metabolism, sequestration and antioxidant activity. Several GSTs genes in Spodoptera litura, a polyphagous agricultural pest, have been demonstrated to be overexpressed and involved in organophosphates and pyrethroids resistance. Previous studies have indicated the significant overexpression of two delta class GSTs genes (SlGSTd3 and SlGSTd4) in organophosphates and pyrethroids resistant populations. Here, they were heterologous expressed, and their metabolism activity and antioxidant activity were determined. Results indicated that the recombinant protein SlGSTD3 and SlGSTD4 both showed metabolism activity to phoxim and chlorpyrifos, but not to fenvalerate, cyhalothrin or beta cypermethrin. The metabolism activity of SlGSTD3 to phoxim and chlorpyrifos is higher than that of SlGSTD4. The recombinant vector of SlGSTD3 and SlGSTD4 both showed antioxidant activity after exposure to cumene hydroperoxide. Further modeling and docking analysis indicated that the 3D structure of SlGSTD3 and SlGSTD4 were well shaped for phoxim and chlorpyrifos, and the binding affinity for phoxim was stronger than that of chlorpyrifos. Our work provides evidence that SlGSTd3 and SlGSTd4 both play roles in phoxim and chlorpyrifos resistance in S. litura.

Host Suitability of Tobacco Leaf Eating Caterpillar (Spodoptera litura F.) under Laboratory Condition

A study was conducted at the Bidi Tobacco Research Station, AAU, Anand laboratory during kharif (June-October 2021) to determine the most suitable host plant of S. litura among the groundnut, tobacco and castor. A statistically designed lab experiment using Completely Randomized Design (CRD) having twenty-five Repetitions and three treatments was laid out. Total life span of S. litura was longer on castor followed by groundnut and least duration was observed on tobacco. The egg hatching % was found more or less similar in each of host crop. Eggs were clustered and covered in tiny buff-colored hairs that resembled hairs on the gravid female’s abdomen tip. The total larval period from the first to sixth instar was recorded longer on castor followed by on groundnut and tobacco. Last larval instar was very active and consuming prolifically on leaves, resulting in the whole leaf being fed with just the mid rib remaining. The pupal period was found similar on three different hosts. Pupa become shiny, greenish in color after that color change from greenish to brownish yellow to light brown to dark brown in color with shiny appearance. Adult longevity of both male and female was found to be longer on castor followed by groundnut and tobacco. Adult moths (both male and female) were yellowish brown in colour, with a prominent head and black compound eyes. The female was somewhat bigger and stouter than the male. Fecundity (egg masses female-1) of adult female was noticed similarly in different host crops. Sex ratio of S. litura on groundnut was 1:1, on castor 1:1.09 and on tobacco 1:1.38.

Functional analysis of UDP-glycosyltransferase genes conferring indoxacarb resistance in Spodoptera litura

UDP-glycosyltransferase (UGT) is the major detoxification enzymes of phase II involved in xenobiotics metabolism, which potentially mediates the formation of insect resistance. Previous transcriptome sequencing studies have found that several UGT genes were upregulated in indoxacarb resistant strains of Spodoptera litura, but whether these UGT genes were involved in indoxacarb resistance and their functions in resistance were unclear. In this study, the UGTs inhibitor, 5-nitrouracil, enhanced the toxicity of indoxacarb against S. litura, preliminarily suggesting that UGTs were participated in indoxacarb resistance. Two UGT genes, UGT33J17 and UGT41D10 were upregulated in the resistant strains and could be induced by indoxacarb. Alignment of UGT protein sequences revealed two conserved donor-binding regions with several key residues that interact with catalytic sites and sugar donors. Further molecular modeling and docking analysis indicated that two UGT proteins were able to stably bind indoxacarb and N-decarbomethoxylated metabolite (DCJW). Furthermore, knockdown of UGT33J17 and UGT41D10 decreased viability of Spli-221 cells and enhanced susceptibility of larvae to indoxacarb. Transgenic overexpression of these genes reduced the toxicity of indoxacarb in Drosophila melanogaster. This work revealed that upregulation of UGT genes significantly contributes to indoxacarb resistance in S. litura, and is of great significance for the development of integrated and sustainable management strategies for resistant pests in the field.

Natural Coumarin Shows Toxicity to Spodoptera litura by Inhibiting Detoxification Enzymes and Glycometabolism.

Coumarin and its derivatives are plant-derived compounds that exhibit potent insecticidal properties. In this study, we found that natural coumarin significantly inhibited the growth and development of Spodoptera litura larvae through toxicological assay. By transcriptomic sequencing, 80 and 45 differentially expressed genes (DEGs) related to detoxification were identified from 0 to 24 h and 24 to 48 h in S. litura after coumarin treatment, respectively. Enzyme activity analysis showed that CYP450 and acetylcholinesterase (AChE) activities significantly decreased at 48 h after coumarin treatment, while glutathione S-transferases (GST) activity increased at 24 h. Silencing of SlCYP324A16 gene by RNA interference significantly increased S. litura larval mortality and decreased individual weight after treatment with coumarin. Additionally, the expression levels of DEGs involved in glycolysis and tricarboxylic acid (TCA) cycle were inhibited at 24 h after coumarin treatment, while their expression levels were upregulated at 48 h. Furthermore, metabonomics analysis identified 391 differential metabolites involved in purine metabolism, amino acid metabolism, and TCA cycle from 0 to 24 h after treated with coumarin and 352 differential metabolites associated with ATP-binding cassette (ABC) transporters and amino acid metabolism. These results provide an in-depth understanding of the toxicological mechanism of coumarin on S. litura.

Lethal and sublethal effects of flubendiamide and spirotetramat against the leaf worm, Spodoptera litura(Fabricius) under laboratory conditions.

The leaf worm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) is a notorious insect pest of many economically important cultivated crops like cotton, maize, tobocco and vegetables causing severe economic losses from 50-100%. In most crops, damage arises due to voracious feeding by the larvae and leads to the skeletonizing of leaves. Toxicological studies were performed to estimate lethal and sublethal levels of flubendiamide and spirotetramat against S. litura. Effects of these estimated values were assessed on different biological traits of S. litura including life duration, survival and next generation potential. Both flubendiamide and spirotetramat showed toxic responses against second instar larvae of S. litura under laboratory conditions. Larval duration and survival rate of S. litura to were significantly different. Exposure to test insecticides resulted in negative effect on the demography of S. litura as longer life cycle and decreased fecundity. Changes in net reproductive rate and intrinsic rate of increase also helped to decide the fate of these insecticides. Low reproductive potential and low hatching percentage due to exposure to test insecticides can help to manage next generation of target pest. These two new chemistry insecticides can be recommended for their effective and long-term utilization against this important leaf feeder which may help its management and decrease economic losses faced by the growers. Their impact on larval duration and low survival rate at lethal levels guides about their potential in pest control.

The lepidopteran pest complex infesting menthol mint in India: Distribution during the crop development, species composition and associated parasitoids

Menthol mint, Mentha arvensis L. is an important aromatic and medicinal herb cultivated as an industrial crop for its essential oil in the Indo-Gangetic plains of India. The commercial production of menthol mint suffers due to defoliation caused by lepidopteran pests and currently becoming a serious constraint for its clean cultivation. The information on occurrence of lepidopteran caterpillars defoliating menthol mint in the region is limited. In this study, we assessed the occurrence and injury caused by lepidopteran pests from seven major menthol mint growing districts of the Indo-Gangetic plains of India. Further, the species composition of lepidopteran pests and their associated parasitoids were also reported. The survey revealed that seven lepidopteran pest infestations were recorded on different phenological growth stages of menthol mint in the Indo-Gangetic plains of India. The larval population density of lepidopteran pests was significantly different between the districts, species and phenological stages of menthol mint. The larval population density of the lepidopteran pest varied between 0.41 ± 0.31 to 2.37 ± 1.43 larvae/m2 across the locations. The higher occurrence of Spodoptera litura (Fabricius), Spilarctia obliqua Walker and Thysanoplusia orichalcea (Fabricius) was recorded in menthol mint. The higher incidence of lepidopteran pests was recorded at the mid-vegetative growth stage of menthol mint. This study found eight parasitoids parasitizing egg and larval stages of lepidopteran pests. The parasitism rate of egg parasitoids, Trichogramma chilonis Ishii and Trichogramma achaeae Nagaraja and Nagarkatti was 23.53–35.31% and 27.78% to the eggs of Helicoverpa armigera and T. orichalcea, respectively. The larval parasitoids caused a total of 5.78% larval parasitism to the various lepidopteran pests of menthol mints. This information provides a current pest status of lepidopteran pests infesting menthol mint in Indo-Gangetic plains of India. This baseline information could be used for the development of management strategies against lepidopteran pests for sustainable menthol mint production.

Biochemical Mechanism of Insecticide Resistance in <i>Spodoptera litura</i> (F) Populations from Uttarakhand

Spodoptera litura populations were collected from different lowland areas and doon valley situated in Uttarakhand and insecticide resistance effect was studied for indoxacarb 14.5% SC, chlorantraniliprole 18.5%SC, fipronil 5% SC, chlorpyriphos 50%+cypermethrin 5% EC and profenofos 40%+cypermethrin 4% EC, also the specific activity of carboxylesterase, acetyl choline esterase, mono-oxygenase and glutathione-s-transferase was studied for biochemical analysis of detoxification enzymes. The scale of infestation was measured and related to temperature and humidity. High infestation has been observed in areas with optimum temperature and humidity. Highest resistance in the study was found against profenofos 40%+chlorpyriphos 4% and fipronil 5%SC with LC50 243.63 µg/ml and 214.22 µg/ ml respectively. On biochemical analysis of detoxification enzymes, it was observed that the highest activity of all the enzymes was observed in Mota Haldu population. Hence, overproduction of detoxification enzymes was found to be responsible for insecticide resistance in S. litura populations studied.

Effect of Different Host Plants on Biology of Tobacco Caterpillar, Spodoptera litura (Fabricius)

The tobacco caterpillar, Spodoptera litura (Fabricius) is present as an economically important and regular polyphagous pests in India and other countries. The knowledge of biology and ecology of an insect pests is a prerequisite for its management. An experiment was conducted on biology of Spodoptera litura (Fabricius) on different host plants in laboratory of the Department of Entomology, Rajasthan College of Agriculture, Maharana Pratap University of Agriculture and Technology, Udaipur, Rajasthan. The results revealed that the minimum and maximum incubation period of S. litura was 2.98 and 3.30 days recorded on castor and cauliflower, respectively. The minimum larval and pre pupal period was 12.96 and 1.00 days recorded on castor. The minimum and maximum pupal period were recorded on cotton (8.27 days) and cauliflower (6.44 days), respectively. The adult male and female moth survival maximum larvae reared on cauliflower 5.00 and 6.90 days whereas minimum on castor 3.95 and 6.00 days, respectively. The maximum percent adult emergence was recorded larvae reared on castor (87.50%) followed by cauliflower (85.00%) whereas minimum on cotton (67.50%). The maximum fecundity was recorded on castor (886.25) followed by soybean (870.00). The entire minimum life cycle was recorded on castor (29.05 days) whereas maximum on cotton (36.50days) followed by soybean (34.24 days). It was concluded that castor is best host plant for S. litura.

Characterization of entomotoxic and nematotoxic genes from indigenous Bacillus thuringiensis strains and their biocontrol potential

BackgroundThe gram pod borer (Helicoverpa armigera Hubner), Bihar hairy caterpillar (Spilosoma obliqua Walker), tobacco caterpillar (Spodoptera litura Fabricius) and root knot nematode (Meloidogyne incognita (Kofoid and White) Chitwood) are the major insect pest and nematodes infesting mungbean, urdbean and other legumes. Bacillus thuringiensis (Bt) is a promising biocontrol agent that helps in managing the above pest. Deploying Bt biopesticides instead of chemical pesticides in legume cultivation enhances the soil health substantially. The present study envisages morphological, molecular cum biochemical characterization, entomotoxicity and nematotoxicity potential of four indigenous Bt strains (Ak2.IIPR, F8.IIPR, F5.IIPR and F6.IIPR) along with HD1 (standard check from BGSC).ResultsThe SEM micrograph analysis of above four Bt strains along with F1.IIPR revealed the presence of different combinations of insecticidal crystal proteins, viz. cuboidal crystal (CC), bipyramidal crystal (BC), spherical crystal (SC) and irregularly pointed crystal (IC). This was further confirmed by PCR amplification of Cry1, Cry2Aa, Cry2Ac, VIP3A and chi36 gene-specific primers and their phylogenetic analysis. F8.IIPR and Ak2.IIPR recorded the highest toxicity index against second-instar S. obliqua larvae (292.56 and 174.55), H. armigera (150.00 and 113.65) and S. litura (210.71 and 114.19) based on probit analysis. F5.IIPR (91.67%) and F8.IIPR (89.00%) recorded the highest juvenile mortality against M. incognita, followed by Ak2.IIPR (70.33%). The protein profiling of supernatant of terrific broth inoculated with F8.IIPR indicated the presence of VIP3A and Cry1I.ConclusionThe present study concluded that F8.IIPR and Ak2.IIPR were potential Bt strains isolated from Indo-Gangetic plains which is having both entomocidal and nematicidal properties. Further, these strains were deposited at national repository, ICAR-NBAIM with the following accession no.: NAIMCC-SB-065 and NAIMCC-SB-066, respectively. These strains can be formulated as microbial biopesticide.

Host trehalose metabolism disruption by validamycin A results in reduced fitness of parasitoid offspring

The general cutworm, Spodoptera litura (Lepidoptera: Noctuidae) is a worldwide destructive omnivorous pest and the endoparasitoid wasp Meteorus pulchricornis (Hymenoptera: Braconidae) is the dominant endoparasitoid of S. litura larvae. Trehalase is a key enzyme in insect trehalose metabolism and plays an important role in the growth and development of insects. However, the specific function of trehalase in parasitoid and host associations has been less reported. In this study, we obtained two trehalase genes (SlTre1 and SlTre2) from our previously constructed S. litura transcriptome database; they were highly expressed in 3rd instar larvae. SlTre1 was mainly expressed in the midgut, and SlTre2 was expressed highest in the head. SlTre1 and SlTre2 were highly expressed 5 days after parasitization by M. pulchricornis. Treatment with the trehalase inhibitor validamycin A significantly inhibited the expression levels of SlTre1 and SlTre2, and the trehalase activity. Besides, the content of trehalose was increased but the content of glucose was decreased 24 h after validamycin A treatment in parasitized S. litura larvae. In addition, the immune-related genes in phenoloxidase (PO) pathway and fatty acid synthesis-related genes in lipid metabolism were upregulated in parasitized host larvae after validamycin A treatment. Importantly, the emergence rate, proportion of normal adults, and body size of parasitoid offspring was decreased in parasitized S. litura larvae after validamycin A treatment, indicating that validamycin A disrupts the trehalose metabolism of parasitized host and thus reduces the fitness of parasitoid offspring. The present study provides a novel perspective for coordinating the application of biocontrol and antibiotics in agroecosystem.