Spodoptera Litura Research Articles

Gut Microbial Diversity Reveals Differences in Pathogenicity between Metarhizium rileyi and Beauveria bassiana during the Early Stage of Infection in Spodoptera litura Larvae.

Beauveria bassiana and Metarhizium rileyi are extensively utilized to investigate fungal pathogenic mechanisms and to develop biological control agents. Notwithstanding, notable distinctions exist in their pathogenicity against the same host insect. This study aimed to elucidate the pathogenic differences between M. rileyi and B. bassiana by examining the impact of various ratios of B. bassiana strain AJS91881 and M. rileyi strain SXBN200920 on fifth instar larvae of Spodoptera litura, focusing on early infection stages and intestinal microbial community structure. The lethal time 50 (LT50) for B. bassiana was significantly lower than that for M. rileyi, indicating greater efficacy. Survival analyses in mixed groups (ratios of 1:9, 1:1, and 9:1 M. rileyi to B. bassiana) consistently demonstrated higher virulence of B. bassiana. Intestinal microbial diversity analysis revealed a significant increase in Achromobacter and Pseudomonas in larvae infected with M. rileyi, whereas Weissella was notably higher in those infected with B. bassiana. Additionally, significant shifts in microbial genera abundances were observed across all mixed infection groups. KEGG pathway enrichment analysis indicated that M. rileyi and B. bassiana employ distinct pathogenic strategies during early infection stages. In vitro tests confirmed the superior growth and stress resistance of B. bassiana compared to M. rileyi, but the antifungal ability of M. rileyi was better than that of B. bassiana. In conclusion, our findings provide preliminary insights into the differential pathogenic behaviors of M. rileyi and B. bassiana during the early infection stages in S. litura larvae, enhancing our understanding of their mechanisms and informing biological pest control strategies in agriculture and forestry.

Gustatory habituation to essential oil induces reduced feeding deterrence and neuronal desensitization in Spodoptera litura

Gustatory habituation to essential oil induces reduced feeding deterrence and neuronal desensitization in Spodoptera litura

Plant growth-promoting rhizobacteria modulate induced corn defense against Spodoptera litura (Lepidoptera: Noctuidae).

Common cutworm, Spodoptera litura is an important pest of corn causing significant crop yield loss. Synthetic insecticides have mostly been used to combat this pest, raising human and environmental health concerns. Plant growth-promoting rhizobacteria (PGPR) could compensate for or augment the harmful effects of agrochemicals. Herein, we aimed to assess whether PGPR-induced defenses in corn plants impact the host-plant selection behavior of S. litura. Headspace volatile organic compounds were analyzed using gas chromatography-mass spectrometry. Larvae fed inoculated corn exhibited lower weights and relative growth rate than noninoculated plants. Under choice experiments, PGPR-treated plants significantly reduced percentage leaf damage area and oviposition rate compared to untreated plants. Volatile organic compound ratio emission varied significantly between control and PGPR treatments, which, in part, explains feeding and oviposition deterrence in PGPR-treated plants. The results demonstrate that PGPR inoculation can enhance corn resistance to S. litura, making it a promising candidate for crop protection strategies.

Measuring the Flight Trajectory of a Free-Flying Moth on the Basis of Noise-Reduced 3D Point Cloud Time Series Data.

Pest control is crucial in crop production; however, the use of chemical pesticides, the primary method of pest control, poses environmental issues and leads to insecticide resistance in pests. To overcome these issues, laser zapping has been studied as a clean pest control technology against the nocturnal cotton leafworm, Spodoptera litura, which has high fecundity and causes severe damage to various crops. For better sighting during laser zapping, it is important to measure the coordinates and speed of moths under low-light conditions. To achieve this, we developed an automatic detection pipeline based on point cloud time series data from stereoscopic images. We obtained 3D point cloud data from disparity images recorded under infrared and low-light conditions. To identify S. litura, we removed noise from the data using multiple filters and a support vector machine. We then computed the size of the outline box and directional angle of the 3D point cloud time series to determine the noisy point clouds. We visually inspected the flight trajectories and found that the size of the outline box and the movement direction were good indicators of noisy data. After removing noisy data, we obtained 68 flight trajectories, and the average flight speed of free-flying S. litura was 1.81 m/s.

Novel report on soil infection with Metarhizium rileyi against soil-dwelling life stages of insect pests.

Entomopathogenic fungi are the most effective control remedy against a wide range of medical and agricultural important pests. The present study aimed to isolate, identify, and assess the virulence of Metarhizium rileyi against Spodoptera litura and Spodoptera frugiperda pupae under soil conditions. The biotechnological methods were used to identify the isolate as M. rileyi. The fungal conidial pathogenicity (2.0 × 107, 2.0 × 108, 2.0 × 109, 2.0 × 1010, and 2.0 × 1011 conidia/mL-1) was tested against prepupae of S. litura and S. frugiperda at 3, 6, 9, and 12 days after treatments. Additionally, the artificial soil-conidial assay was performed on a nontarget species earthworm Eudrilus eugeniae, using M. rileyi conidia. The present results showed that the M. rileyi caused significant mortality rates in S. litura pupae (61-90%), and S. litura pupae were more susceptible than S. frugiperda pupae (46%-73%) at 12 day posttreatment. The LC50 and LC90 of M. rileyi against S. litura, were 3.4 × 1014-9.9 × 1017 conidia/mL-1 and 6.6 × 105-4.6 × 1014 conidia/mL-1 in S. frugiperda, respectively. The conidia of M. rileyi did not exhibit any sublethal effect on the adult stage of E. eugeniae, and Artemia salina following a 12-day treatment period. Moreover, in the histopathological evaluation no discernible harm was observed in the gut tissues of E. eugeniae, including the lumen and epithelial cells, as well as the muscles, setae, nucleus, mitochondria, and coelom. The present findings provide clear evidence that M. rileyi fungal conidia can be used as the foundation for the development of effective bio-insecticides to combat the pupae of S. litura and S. frugiperda agricultural pests.

A novel spider venom peptide from the predatory mite Neoseiulus barkeri shows lethal effect on phytophagous pests

The long-term use of pesticides in the field, and the high fertility and adaptability of phytophagous mites have led to resistance problems; consequently, novel safe and efficient active substances are necessary to broaden the tools of pest mite control. Natural enemies of arthropods typically secrete substances with paralytic or lethal effects on their prey, and those substances are a resource for future biopesticides. In this study, two putative venom peptide genes were identified in a parasitic mite Neoseiulus barkeri transcriptome. Recombinant venom NbSP2 peptide injected into Tetranychus cinnabarinus mites was significantly more lethal than recombinant NBSP1. NbSP2 was also lethal to Spodoptera litura when injected but not when fed to third instar larvae. The interaction proteins of NbSP2 in T. cinnabarinus and S. litura were identified by affinity chromatography. Among these proteins, ATP synthase subunit β (ATP SSβ) was deduced as a potential target. Four binding sites were predicted between NBSP2 and ATP SSβ of T. cinnabarinus and S. litura. In conclusion, we identified a venom peptide with activity against T. cinnabarinus and S. litura. This study provides a novel component for development of a new biological pesticide.

Antifeedant Activity of Crude Extracts and Fractions Isolated from Cymodocea serrulate (R.Br.) Leaf against Tobacco Caterpillar Spodoptera litura (Fab.) Lepidoptera: Noctuidae

Different organic solvent extracts of Cymodocea serrulata leaves exhibited antifeedant activity against Spodoptera litura larvae. Maximum antifeedant activity (88.95%) was observed in ethyl acetate extract at a 5 percent concentration. Five fractions were isolated from ethyl acetate extract by column chromatography and tested individually at four different concentrations, viz., 125, 250, 500, and 1000 ppm, for antifeedant activity. Among the five fractions, fraction I showed promising antifeedant activity (91.12%) at a 1000 ppm concentration. Deformities in larvae, pupae, and adults were also recorded. The preliminary phytochemical analysis showed the presence of alkaloids, terpenoids, flavonoids, tannins, phenolic compounds, glycosides, and steroids.

Gustatory Receptor 206 Participates in the Foraging Behavior of Larvae of Polyphagous Pest Spodoptera litura.

Insect gustatory receptors (GRs) aid in the precise identification of deterrent or stimulant compounds associated with food, mating, and egg-laying. Thus, they are promising targets for developing efficient insecticides. Here, 61 GRs in the chemosensory organs of Spodoptera litura larvae and adults were identified. Among them, SlitGR206 exhibited larval labium (LL)-specific expression characteristics. To explore the role of SlitGR206, a bacterial expression system was established to produce high-quality double-stranded RNA (dsRNA) and suppress SlitGR206 expression in LL. Subsequent behavioral assessments revealed that SlitGR206 silencing influenced larval feeding preferences and absorption. Moreover, it was found to reduce the ability of larvae to forage the five crucial host odorants. These findings demonstrate that SlitGR206 likely plays an indirect regulatory role in host recognition, consequently affecting foraging behavior. This provides a crucial foundation for the analysis of functional diversity among insect GRs and the precise development of nucleic acid pesticides in the future.

Smart and Sustainable Crop Protection: Design and Evaluation of a Novel α-Amylase-Responsive Nanopesticide for Effective Pest Control.

In this study, an α-amylase-responsive controlled-release formulation was developed by capping polydopamine onto β-cyclodextrin-modified abamectin-loaded hollow mesoporous silica nanoparticles. The prepared Aba@HMS@CD@PDA were subjected to characterization using various analytical techniques. The findings revealed that Aba@HMS@CD@PDA, featuring a loading rate of 18.8 wt %, displayed noteworthy release behavior of abamectin in the presence of α-amylase. In comparison to abamectin EC, Aba@HMS@CD@PDA displayed a significantly foliar affinity and improved rainfastness on lotus leaves. The results of field trail demonstrated a significantly higher control efficacy against Spodoptera litura Fabricius compared to abamectin EC at all concentrations after 7, 14, and 21 days of spaying, showcasing the remarkable persistence of Aba@HMS@CD@PDA. These results underscore the potential of Aba@HMS@CD@PDA as a novel and persistently effective strategy for sustainable on-demand crop protection. The application of nanopesticides can enhance the effectiveness and efficiency of pesticide utilization, contributing to more sustainable agricultural practices.

Nitrogen-mediated volatilisation of defensive metabolites in tomato confers resistance to herbivores.

Plants synthesise a vast array of volatile organic compounds (VOCs), which serve as chemical defence and communication agents in their interactions with insect herbivores. Although nitrogen (N) is a critical resource in the production of plant metabolites, its regulatory effects on defensive VOCs remain largely unknown. Here, we investigated the effect of N content in tomato (Solanum lycopersicum) on the tobacco cutworm (Spodoptera litura), a notorious agricultural pest, using biochemical and molecular experiments in combination with insect behavioural and performance analyses. We observed that on tomato leaves with different N contents, S. litura showed distinct feeding preference and growth and developmental performance. Particularly, metabolomics profiling revealed that limited N availability conferred resistance upon tomato plants to S. litura is likely associated with the biosynthesis and emission of the volatile metabolite α-humulene as a repellent. Moreover, exogenous application of α-humulene on tomato leaves elicited a significant repellent response against herbivores. Thus, our findings unravel the key factors involved in N-mediated plant defence against insect herbivores and pave the way for innovation of N management to improve the plant defence responses to facilitate pest control strategies within agroecosystems.

Immature Stages and Chaetotaxy of <i>Spodoptera Litura</i> (F)

This study explores the chaetotaxy, and biology of immature stages of the tobacco cutworm, Spodoptera litura (F) which is a major pest of crops. From Himachal Pradesh, apricot (Prunus armeniaca), curly dock weed (Rumex crispus), apple (Malus domestica) and plum (Prunus salicina) are reported as its new hosts. It takes 29-39.32 days to complete its lifecycle with six larval instars. The chaetotaxy of final instar and pupal morphology are described and illustrated.

Evaluation and Identification of Novel Insecticidal Toxin Genes From <i>Bacillus Thuringiensis</i> (Berliner) Isolates

The present study evaluated fifteen Bacillus thuringiensis (Berliner) isolates against second instar larvae of tobacco leaf eating caterpiller Spodoptera litura (F) and Vip genes were identified in the effective isolates. Four NCIM isolates (5111, 5112, 5116 and 5117) were found promising, and their LC50 ranged from 2.5x105 to 3.33x105 ppm and 2.20x105 to 2.85x105 ppm in diet incorporation and surface contamination methods, respectively. The NCIM-5111 isolate exhibited the lowest LC50 of 2.5x105 ppm in diet incorporation and 2.2x105 ppm in the surface contamination method. Surface contamination method revealed more mortality of 6.66 to 10.00% across the NCIM isolates. All the isolates were further used for identification of insecticidal toxin (Vip, Cyt) genes, and it was observed that four NCIM isolates harbour the Vip3Aa1 gene and one viz., NCIM-5112 isolate carries the Vip1/ Vip2 gene, which has distinct motifs from the Vip toxins that are currently in use.

Assessment of Insecticide Resistance in Spodoptera litura (Fabricius) in Vegetable Crop Ecosystem

One of the most prevalent insect pests is the tobacco caterpillar or Spodoptera litura (Fabricius), which results in significant crop losses developed resistance against different insecticides over time. This laboratory experiment was carried out in the Department of Entomology, College of Agriculture, Rajendranagar, Professor Jayashankar Telangana State Agricultural University (PJTSAU), Hyderabad during Karif, 2022. The susceptible population was reared in laboratory continuously for ten generation without exposing it to insecticides. The susceptibility of field populations of S. litura that were collected from many vegetable crops in the intense vegetable crop cultivating mandals i.e., Chevella and Maheshwaram of Rangareddy district to commonly used insecticides viz., chlorantraniliprole, emamectin benzoate and flubendamide was then compared with a laboratory reared susceptible population The bioassay studies revealed that the LC50 values of these insecticides were significantly higher in the field population collected from Chevella and Maheshwaram compared to the susceptible laboratory population. Based on the LC50 values the Resistant ratio (RR) was calculated for the field populations. It was found that Chevella population developed 35.34 folds resistance and Maheshwaram population also developed nearly 34.90-fold resistance against emamectin benzoate. Both Chevella and Maheshwaram populations were found to develop moderate resistance of 28.23 and 27.35-fold against flubendamide and comparatively lower resistance of 21.05 and 23.44-fold resistance against chlorantraniliprole when compared to susceptible population. These findings further helps in developing better IRM strategies.

Systemic defense induced by fatty acid compounds from marine macroalgae, Chaetomorpha antennina in tomato (Solanum lycopersicum) plants alters the susceptibility of the polyphagous agricultural pest, Spodoptera litura Fab

BackgroundSeaweeds contain a widespread range of fatty acids (FA), and several of them have potential bioactivity. FAs are dynamic members of all biota, as well as being acknowledged for their critical function in initiating phytohormone interactions and acting as important participants in many defense signalling pathways of the plant system. The current study looks at the defense-eliciting potentials of fatty acids from the green seaweed Chaetomorpha antennina (Bory) Kützing and their impact on the polyphagous insect pest Spodoptera litura (Fab).ResultsThe seaweed was detected with 19 fatty acids, with larger proportion of hexa and octadecanoic and linoleic acids. The algal fatty acid compounds (CFA) were successful in eliciting salicylic acid and phenolic compounds biosynthesis along with defense enzymes peroxidase (PO) and polyphenol oxidase (PPO). CFA enhanced the synthesis of defense enzymes, PO and PPO and phenols, post infestation with S. litura (> 50%) compared to control plants exposed to the pest. CFA was also effective in causing direct mortalities (96–98%) to the larvae (II-V instars). S. litura larvae exposed to elicited tomato plants displayed physiological incursions that extended larval-pupal duration to 26–28 days, preventing both morphogenetic transitions as well as affecting their morphology, that lead to the emergence of adults with malformed wings, legs. As a consequence, the fecundity was reduced by 60% affecting the reproductive performances of second-generation adults. The consumption rate (RCR) of larvae exposed to CFA was decreased by 84%, depicting feeding deterrence. These larvae were also observed with > 50% reduction in the levels of phosphatase enzyme secretion, bringing down larval growth rate from 0.58 to 0.34 mg/day. Histological analysis of exposed larvae displayed midgut cell disruption.ConclusionHence, the study finally confirms the elicitor potentials of fatty acid compounds from C. antennina, by inducing natural systemic defenses. This investigation unlocks novel forecasts besides delivering an unconventional method for crop protection to moderate or interchange the solicitation of chemical pesticides.Graphical

Migration Activity of Spodoptera litura (Lepidoptera: Noctuidae) between China and the South-Southeast Asian Region.

The common cutworm, Spodoptera litura (F.), feeds on a wide variety of food and cash crops and is one of the most widespread and destructive agricultural pests worldwide. Migration is the biological basis of its regional population outbreaks but the seasonal movement of this pest between east and south Asia regions remains unknown. In this study, searchlight traps were used to monitor the seasonal migration of S. litura from 2019 to 2023 in Ruili City (Yunnan, China), located along the insect migratory route between China and the south Asia region. The results showed that migratory activity could occur throughout the year, with the main periods found in spring (April-May) and autumn (October-December). The ovarian development and mating status of the trapped females indicated that most individuals were in the middle or late stages of migration and that Ruili City was located in the transit area of the long-distance migration of the pest. In the migration trajectory simulation, populations of S. litura moved from northeast India, Bangladesh, and northern Myanmar to southwestern China along the southern margin of the Himalayas in spring and returned to the south Asia region in autumn. Our findings clarify the seasonal migration patterns of S. litura in China and South Asia and facilitate the development of regional cross-border monitoring and management systems for this pest.

New prospective insecticidal agents based on thiazolo[4,5-b]quinoxaline derivatives against cotton leafworm Spodoptera litura (Fabricius): Design, synthesis, toxicological, morphology, histological, and biomedical studies

In this study, a new series of thiazolo[4,5-b]quinoxaline derivatives 3–8 were synthesized by treating 2,3-dichloroquinoxaline with thiosemicarbazone and thiourea derivatives under reflux conditions. The chemical structure of the newly designed derivatives was conducted using spectroscopic techniques. The insecticidal bioassay of the designed derivatives was evaluated against the 2nd and 4th larvae of S. litura after five days as toxicity agents via median lethal concentration (LC50) and the lethal time values (LT50). The results indicated that all the tested compounds had insecticidal effects against both instar larvae of S. litura with variable values. Among them, thiazolo[4,5-b]quinoxaline derivative 3 was the most toxic, with LC50 = 261.88 and 433.68 ppm against 2nd and 4th instar larvae, respectively. Moreover, the thiazolo[4,5-b]quinoxaline derivative 3 required the least time to kill the 50% population (LT50) of 2nd larvae were 20.88, 13.2, and 15.84 hs with 625, 1250, and 2500 ppm, respectively, while for the 4th larval instar were 2.75, 2.08, and 1.76 days with concentrations of 625, 1250, and 2500 ppm, respectively. Larvae's morphological and histological studies for the most active derivative 3 were investigated. According to SEM analysis, the exterior morphology of the cuticle and head capsule was affected. In addition, there were some histological alterations in the cuticle layers and the midgut tissues. Columnar cells began breaking down, and vacuolization occurred in the peritrophic membrane. Moreover, treating 4th S litura larvae hemolymph with compound 3 showed significant changes in biochemical analysis, such as total proteins, GPT, GOT, acetylcholinesterase (AChE), and alkaline phosphatase (AlP). Finally, the toxicity prediction of the most active derivative revealed non-corrosive, non-irritant to the eye, non-respiratory toxicity, non-sensitivity to the skin, non-hepatotoxic, and don't have toxicity on minnow toxicity and T. pyriformis indicating a good toxicity profile for human.

Performance and preference of larval parasitoid, Microplitis pallidipes (Hymenoptera: Braconidae), on 2 Spodoptera pest species.

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Spodoptera litura (Fabricius) are the main pests on corn (Poaceae: Gramineae). The performance of the larval wasp, Microplitis pallidipes Szépligeti (Hymenoptera: Braconidae), was reported on S. frugiperda and S. litura. In this study, we evaluated host selectivity, constructed an age-stage, 2-sex life table, and assessed the pest control potential of M. pallidipes against these 2 pests under laboratory conditions. In a 2-choice host preference experiment, M. pallidipes exhibited a stronger preference for S. frugiperda over S. litura and a distinct preference for second instars. We also investigated the parasitism of females that were either unfed or fed with 10% honey-water solution under different host densities and found that the highest parasitism rate was observed when M. pallidipes were fed with honey-water solution on the first day after mating and a presented female wasp:host ratio of 1:90. In a nonselective assay, M. pallidipes successfully completed a full generation on both hosts. However, the parasitoids exhibited higher fitness and population growth potential when reared on S. frugiperda, with a net reproductive rate (R0) of 24.24, an intrinsic rate of increase (r) of 0.20 per day, a finite rate of increase (λ) of 1.23 per day, and a mean generation time (T) of 15.69 days. This study elucidates the performance of M. pallidipes on 2 Spodoptera host species and offers insights into its biological control potential on lepidopteran pests.

Application of majapahit (Crescentia cujete L.) fruit extract to control armyworm (Spodoptera litura Fabricius, 1775) infestation in Chinese mustard crops

Spodoptera litura poses a threat to important crops in Indonesia, leading to productivity failure and economic repercussions. Botanical insecticides have garnered attention in crop cultivation due to their easy applicability and effectiveness against specific pests. In this study, the effectiveness of majapahit (Crescentia cujete), a popular medicinal plant, in reducing S. litura infestation was investigated through in planta test using Chinese mustard (Brassica chinensis var. parachinensis). The experiment followed a completely randomized design (CRD) with four treatments of C. cujete fruit extract at concentrations of 0, 20, 40, 60, and 80%, each replicated four times. Parameters observed in this study included the growth profile of mustard plants (plant height, number of plants, fresh weight), leaf damage index (LDI), and mortality after application for 30 days after planting. Results revealed a significant concentration-response relationship for both the LDI values and mortality rates. The determination of LC50 for C. cujete fruit extract yielded a value of 29%. The use of C. cujete as an insecticidal agent warrants promotion, and further investigation with a larger sample population and different target crops is necessary in the future.

Seasonal Incidence of Insect Pests and Natural Enemies in Foxtail Amaranthus and Spinach and Efficacy of Dimethoate Against Insect Pests Infesting Leafy Vegetables

An investigation was made to study the efficacy of dimethoate against sucking and defoliator pest-infesting foxtail amaranths and spinach. The efficacy of dimethoate was evaluated at two doses, one at the recommented does of 200 g active ingredient (a.i.) ha-1 and other at double the recommended dose of 400 g a.i. ha-1 along with control and the other at double the recommended dose of 400 g a.i ha-1 along with control. The incidence of leaf webber (Hymenia recurvalis), ear-head bug (Cletus pugnator), Thrips (Thrips tabaci) and leaf miner (Liriomyza trifoli) were observed in foxtail amaranth. In spinach, leaf-eating caterpillars (Spodoptera litura), cutworm (Agrotis ipsilon) and Thrips (Thrips tabaci) were recorded. In spinach at the third leaf stage, nearly 9.20% leaf defoliation, 10.34% leaf damage and a mean thrips population of 3.48/five plants with a mean predator population of 0.32/ five plants were recorded. In the efficacy study, dimethoate was efficient in reducing the infestation of the leaf webber population with pre-mean count of 4.4± 0.87 in control and 1.2± 0.03 in X dose and 0.0± 0.0 in 2X dose after a day after treatment (DAT) in foxtail amaranths. In an efficacy study of dimethoate on thrips in spinach and foxtail amaranth, a complete reduction of thrips population was observed on 3 DAT at X dose and 2X dose with mean thrips population on control was 17.1± 2.12 in spinach and 8.5± 1.24 in foxtail amaranth 3 DAT. These findings indicate that dimethoate application has promising potential as a practical approach for managing insect pests in foxtail amaranth and spinach crops.

Characterization of Neuropeptides from Spodoptera litura and Functional Analysis of NPF in Diet Intake.

Neuropeptides are involved in many biological processes in insects. However, it is unclear what role neuropeptides play in Spodoptera litura adaptation to phytochemical flavone. In this study, 63 neuropeptide precursors from 48 gene families were identified in S. litura, including two neuropeptide F genes (NPFs). NPFs played a positive role in feeding regulation in S. litura because knockdown of NPFs decreased larval diet intake. S. litura larvae reduced flavone intake by downregulating NPFs. Conversely, the flavone intake was increased if the larvae were treated with NPF mature peptides. The NPF receptor (NPFR) was susceptible to the fluctuation of NPFs. NPFR mediated NPF signaling by interacting with NPFs to regulate the larval diet intake. In conclusion, this study suggested that NPF signaling regulated diet intake to promote S. litura adaptation to flavone, which contributed to understanding insect adaptation mechanisms to host plants and provide more potential pesticidal targets for pest control.