Spodoptera Litura Fabricius Research Articles

Screening of newly isolated indigenous entomopathogenic nematodes against Spodoptera litura Fabricius (Lepidoptera: Noctuidae)

Aim: Insecticides have traditionally been used to control S. litura, although bio-pesticides as alternative control measures are also in demand due to soil residual issues and other environmental dangers. Another safe technique for controlling this important pest is entomopathogenic nematodes (EPNs). Methodology: This study evaluated the infectivity of ten native recently isolated entomopathogenic nematodes against S. litura by assessing their penetration and multiplication in S. litura. The efficiency of the promising EPNs against second, third and fourth instars S. litura larvae was further examined. Results: Among the tested EPNs, Steinernema sp. (IARI-EPN RP 03), Heterorhabditis sp. (IARI-EPN RP 06), and Oscheius sp. (IARI-EPN RP 07) were intensely harmful to S. litura, producing 100 percent mortality in 72 hrs, followed by Steinernema sp. (IARI-EPN RP 09), which caused 92 percent mortality, and Oscheius sp. (IARI-EPN RP 10) was the least pathogenic recording 58 percent mortality. Heterorhabditis sp. (IARI-EPN RP 06) showed the maximum penetration, followed by Oscheius sp. (IARI-EPN RP 07) and Oscheius sp. (IARI-EPN RP 08), with Oscheius sp. (IARI-EPN RP 04) showed the least penetration. The second instar larvae of S. litura were highly vulnerable to EPNs, followed by third and fourth instar larvae. According to the findings, Steinernema sp. (IARI-EPN RP 03) and Heterorhabditis sp. (IARI-EPN RP 06) were most virulent against S. litura. Interpretation: As a result, both EPNs have the potential to act as biological control agents for S. litura. Furthermore, the fifth instar S. litura larva were more suited for multiplication, indicating that this insect is suitable for EPN production. Field testing of these promising EPNs will reveal their efficacy in managing S. litura in a sustainable manner. Key words: Bio-pesticides, Entomopathogenic nematodes, Heterorhabditis, Insects, Oscheius, Steinernema

Susceptibility of Different Developmental Stages of the Tobacco Cutworm, Spodoptera litura (Fabricius) to Entomopathogenic Nematode, Steinernema abbasi PN-1

The tobacco cutworm, Spodoptera litura Fabricius is a widely distributed polyphagous pest that is causing economic damage to different crop plants. Many pesticides have been used extensively to control S. litura, but they are currently ineffective because of the development of pesticide resistance and their detrimental effects on the environment and human health. Although entomopathogenic nematodes (EPNs) have been employed as biological control agents against S. litura, little is known about the pathogenicity of these EPNs. Here we studied the virulence of Steinernema abbasi PN-1 against different stages of S. litura. The results reveled that all tested larval stages and pupae of S. litura were found susceptible to S. abbasi. There was a positive correlation between insect mortality and the nematode concentration. The S. abbasi caused 100 per cent larval mortality at 48-60 h of post treatment in all tested doses in laboratory. There was a positive correlation between insect mortality and the nematode concentration while the time to cause complete mortality was negatively correlated with the increase in larval days and nematode concentration. However, further field studies are required use S. abbasi as efficient biological control agents against S. litura.

Immobilization of Bacillus thuringiensis Cry1Ac in metal-organic frameworks through biomimetic mineralization for sustainable pest management

Traditional chemical pesticide dosage forms and crude application methods have resulted in low pesticide utilization, increased environmental pollution, and the development of resistance. Compared to traditional pesticides, nanopesticides enhance the efficiency of pesticide utilization and reduce the quantity required, thereby decreasing environmental pollution. Herein, Cry1Ac insecticidal crystal protein from Bacillus thuringiensis Subsp. Kurstaki HD-73 was encapsulated in a metal-organic framework (zeolite imidazolate framework-8, ZIF-8) through biomimetic mineralization to obtain Cry1Ac@ZIF-8 nanopesticides. The Cry1Ac@ZIF-8 nanopesticides exhibited a dodecahedral porous structure, and the introduction of Cry1Ac did not affect the intrinsic crystal structure of ZIF-8. The indoor toxicity analysis revealed that the toxicity of Cry1Ac towards Ostrinia furnacalis (Guenée), Helicoverpa armigera Hubner, and Spodoptera litura Fabricius was not affected by ZIF-8 encapsulation. Surprisingly, Cry1Ac@ZIF-8 still exhibited excellent pest management efficacy even after exposure to heat, UV irradiation, and long-term storage. More importantly, the encapsulation of ZIF-8 significantly enhanced the internal absorption performance of Cry1Ac in maize leaves and extended its persistence period. Thus, ZIF-8 could potentially serve as a promising carrier for the preparation of nanopesticides with enhanced applicability, stability, and persistence period, providing a powerful strategy to improve the application of Cry1Ac in future agricultural pest management.

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.

One‐pot preparation of nanoparticles via self‐assembly of sodium lignosulfonate and quaternary ammonium for controlled release of emamectin benzoate

AbstractNanoformulation was an important strategy to reduce the use of pesticides and the impacts on the environment. However, complex process and high cost hurdled the application in agriculture. In this work, sodium lignosulfonate (SL) and cetyltrimethyl ammonium chloride (CTAC) were combined into nanoparticles and utilized as carriers for emamectin benzoate (EB), using a one‐pot method at mild conditions. The structure of nanoparticle was investigated by dynamic light scattering, ζ‐potential measurement, Fourier transform infrared spectroscopy, and transmission electron microscopy, and related to the loading and release properties. The mass ratio of SL and CTAC had great impacts on the structure of nanoparticle. The release of EB from SL‐CTAC nanoparticles was pH‐triggered. The retarding efficacy was enhanced in the medium of higher pH, due to the increased interaction between the EB and carrier. The incorporation into the nanoparticles greatly increased the insecticidal toxicity of EB. The median lethal concentration, against Spodoptera litura Fabricius larvae, of typical nanoformulation was 55% and 63% of that of conventional formulation emulsifiable concentrates after feeding for 24 and 48 h, respectively. The results indicated SL‐CTAC nanoparticles were good candidates of nanovehicles with high efficiency and low‐cost, which was of great significance to prompt the nanopesticides from laboratory investigation to agricultural application.

The Identification of a Quantative Trait Loci-Allele System of Antixenosis against the Common Cutworm (Spodoptera litura Fabricius) at the Seedling Stage in the Chinese Soybean Landrace Population.

Common cutworm (CCW) is an omnivorous insect causing severe yield losses in soybean crops. The seedling-stage mini-tray identification system with the damaged leaf percentage (DLP) as an indicator was used to evaluate antixenosis against CCW in the Chinese soybean landrace population (CSLRP) under three environments. Using the innovative restricted two-stage multi-locus genome-wide association study procedure (RTM-GWAS), 86 DLP QTLs with 243 alleles (2-11/QTL) were identified, including 66 main-effect loci with 203 alleles and 57 QTL-environment interaction loci with 172 alleles. Among the main-effect loci, 12 large-contribution loci (R2 ≥ 1%) explained 25.45% of the phenotypic variation (PV), and 54 small-contribution loci (R2 < 1%) explained 16.55% of the PV. This indicates that the CSLRP can be characterized with a DLP QTL-allele system complex that has not been found before, except for a few individual QTLs without alleles involved. From the DLP QTL-allele matrix, the recombination potentials expressed in the 25th percentile of the DLP of all possible crosses were predicted to be reduced by 41.5% as the maximum improvement and 14.2% as the maximum transgression, indicating great breeding potential in the antixenosis of the CSLRP. From the QTLs, 62 candidate genes were annotated, which were involved in eight biological function categories as a gene network of the DLP. Changing from susceptible to moderate plus resistant varieties in the CSLRP, 26 QTLs had 32 alleles involved, in which 19 genes were annotated from 25 QTL-alleles, including eight increased negative alleles on seven loci and 11 decreased positive alleles on 11 loci, showing the major genetic constitution changes for the antixenosis enhancement at the seedling stage in the CSLRP.

Rational Design of Insecticidal Isoxazolines Containing Sulfonamide or Sulfinamide Structure as Antagonists of GABA Receptors with Reduced Toxicities to Honeybee and Zebrafish.

To develop highly effective, nontarget organism-friendly insecticides based on the isoxazoline scaffold, we rationally designed and synthesized 25 isoxazoline derivatives containing sulfonamides and sulfinamides. Their insecticidal activities against the diamondback moth (Plutella xylostella), fall armyworm (Spodoptera frugiperda), beet armyworm (Spodoptera exigua), and Spodoptera litura Fabricius (S. litura) were evaluated. The trifluoromethyl sulfinamide-containing compound 7w displayed excellent activities with LC50 values being 0.09, 0.84, 0.87, and 0.68 mg/L against P. xylostella, S. frugiperda, S. exigua, and S. litura, respectively, which were superior to fluxametamide (LC50 = 0.09, 1.24, 1.10, and 0.65 mg/L, respectively) and maintained at the same order of magnitude LC50 values as fluralaner (LC50 = 0.02, 0.17, 0.12, and 0.19 mg/L, respectively). Importantly, compound 7w showed a medium toxicity level of acute toxicity to honeybee (LD50 = 2.22 μg/adult), which is significantly lower than the fluralaner (high toxicity level, LD50 = 0.09 μg/adult). Acute toxicity experiments with zebrafish (Danio rerio) indicated that compound 7w was safe with the LC50 value being 42.4 mg/L (low toxicity level). Furthermore, electrophysiological experiments and molecular docking studies preliminarily verified that compound 7w acts on the insect GABA receptor, and the theoretical calculations explained that the sulfinamide structure may play an important role in exhibiting biological activities. The above results suggest that compound 7w could be employed as a potentially highly effective, environmentally friendly insecticide to control multiple agricultural pests.

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.

Relative activity of 15 bacterial strains against the larvae of Helicoverpa armigera, Spodoptera exigua, and Spodoptera litura (Lepidoptera: Noctuidae).

Crystal toxins produced by different strains of entomopathogenic Bacillus thuringiensis (Bt) have been characterized and widely applied as commercial biological pesticides owing to their excellent insecticidal properties. This study aimed to identify novel bacterial strains effective in controlling Spodoptera exigua Hübner, Helicoverpa armigera Hübner, and Spodoptera litura Fabricius. Fifteen culturable bacterial strains were isolated from 60 dead larvae (H. armigera and S. exigua) collected in the field. The biochemical characteristics and 16S rRNA sequences of these strains indicated that one strain (B7) was Lysinibacillus sp., 12 strains (B1, B3, B4, B5, B6, B8, P2, P3, P4, P5, P6, and DW) were Bt kurstaki, and P2-2 and B2 were Bacillus velezensis subsp. Laboratory bioassays indicated that strains B3, P6, B6, and P4 showed high toxicity to second-instar larvae of S. exigua, with LC50 values of 5.11, 6.74, 205.82, and 595.93 µg/ml, respectively; while the strains P5, B5, B6, and P6, were the most efficient against second-instar larvae of H. armigera with LC50 values of 725.82, 11,022.72, 1,282.90, 2,005.28, respectively, and strains DW, P3, P2, and B4 had high insecticidal activity against second-instar larvae of S. litura with LC50 values of 576.69, 1,660.96, 6,309.42, and 5,486.10 µg/ml, respectively. In conclusion, several Bt kurstaki strains with good toxicity potential were isolated and identified in this study. These strains are expected to be useful for biointensive integrated pest management programs to reduce the use of synthetic insecticides.

Biocontrol effect of entomopathogenic fungi Metarhizium anisopliae ethyl acetate-derived chemical molecules: An eco-friendly anti-malarial drug and insecticide.

Insect pests represent a major threat to human health and agricultural production. With a current over-dependence on chemical insecticides in the control of insect pests, leading to increased chemical resistance in target organisms, as well as side effects on nontarget organisms, the wider environment, and human health, finding alternative solutions is paramount. The employment of entomopathogenic fungi is one such potential avenue in the pursuit of greener, more target-specific methods of insect pest control. To this end, the present study tested the chemical constituents of Metarhizium anisopliae fungi against the unicellular protozoan malaria parasite Plasmodium falciparum, the insect pests Anopheles stephensi Listen, Spodoptera litura Fabricius, and Tenebrio molitor Linnaeus, as well as the nontarget bioindicator species, Eudrilus eugeniae Kinberg. Fungal crude chemical molecules caused a noticeable anti-plasmodial effect against P. falciparum, with IC50 and IC90 values of 11.53 and 7.65 µg/mL, respectively. The crude chemical molecules caused significant larvicidal activity against insect pests, with LC50 and LC90 values of 49.228-71.846 µg/mL in A. stephensi, 32.542-76.510 µg/mL in S. litura, and 38.503-88.826 µg/mL in T. molitor at 24 h posttreatment. Based on the results of the nontarget bioassay, it was revealed that the fungal-derived crude extract exhibited no histopathological sublethal effects on the earthworm E. eugeniae. LC-MS analysis of M. anisopliae-derived crude metabolites revealed the presence of 10 chemical constituents. Of these chemicals, three major chemical constituents, namely, camphor (15.91%), caprolactam (13.27%), and monobutyl phthalate (19.65%), were highlighted for potential insecticidal and anti-malarial activity. The entomopathogenic fungal-derived crude extracts thus represent promising tools in the control of insect pests and malarial parasites.

Phenolic secondary metabolites from Acorus calamus (Acorales: Acoraceae) rhizomes: the feeding deterrents for Spodoptera litura (Lepidoptera: Noctuidae).

Spodoptera litura Fabricius (Lepidoptera: Noctuidae) is one of the most destructive pests of various crops cultivated in Thailand. Spodoptera litura larvae, at early stages, attack the leaves and feed on every part of infested crops in later stages. Acorus calamus essential oil contains toxic asarones, which are generalistic cytotoxic compounds. However, the present study is the first attempt to look at safer metabolites from the rhizomes that could deter insect feeding. The objective was to use such compounds as safer residues on crops that would prevent the feeding of herbivorous lepidopterans. Accordingly, phenolic metabolites were isolated and evaluated to establish the feeding deterrence against polyphagous S. litura larvae. Methanol extract of A. calamus, chrysin, and 4-hydroxy acetophenone compounds were the most effective feeding deterrents with FD50 of 87.18, 10.33, and 70.77 µg/cm2, respectively, after 4 h of feeding on treated kale leaves in a no-choice leaf disc assay. Chrysin also reduced carboxylesterase activities (1.37-fold), whereas A. calamus methanol extract reduced glutathione-S-transferase activities (1.44-fold). Some larvae were also seen dead if they consumed the treated kale leaves. Feeding deterrent activity in the methanol extract of A. calamus was due to chrysin and 4-hydroxy acetophenone. The large-scale utilization of such compounds could help develop feeding deterrent strategies in the integrated pest management of lepidopterans.

Pathogenicity of endophytic bacteria as entomopathogens against Spodoptera litura fabricius. (Lepidoptera: noctuidae)

One of the biological controls of pest and plant disease is the use of enophytic bacteria. This study aimed to obtain endophytic bacterial from the root tissue of the shallot plant, which is potential as entomopathogens against the larvae of Spodoptera litura. This research was arranged in a completely randomized design (CRD) with nine treatments consisting of eight endophytic bacteria (isolation from shallot root tissue) and one control with three replications. Parameters observed were larval mortality, percentage of normal and abnormal pupae formed, percentage of normal and abnormal imago formed. The results showed that the bacteria of Serratia marcescens JB1E3 and Bacillus cereus P.14 caused the highest mortality in the larval phase, while Serratia marcescens ULG1E4 and Bacillus sp. SJI showed a long-term (latent) effect, resulting in no formation of pupa and imago of Spodoptera litura.

Effect of insecticides on locomotory behaviour and enzyme activity of Spodoptera litura (Fabricius) populations from Punjab

Aim: The variations in locomotory behaviour and enzyme activity, i.e., acetylcholinesterase and general esterases of Spodoptera litura Fabricius larval populations collected from different regions of Punjab, i.e., Amritsar, Kapurthala and Ludhiana were investigated in the laboratory prior exposure to different insecticides. Methodology: The test larvae were exposed to sublethal doses of different insecticides via surface and food treatment. For locomotory behaviour, they were allowed to move on treated surface and their movements were recorded with an automated video tracking system, Ethovision while on other hand food treatment was opted for observing the influence on enzyme activity. Results: The pronounced variations were observed in the locomotor behaviour of S. litura upon surface exposure of different insecticides. The larva travelled more distance with higher speed and larger turn angle on insecticide-treated surfaces than the untreated ones, while on comparison of different larval populations, the Amritsar population larvae travelled less distance with low speed and maximum turnings. The decrease in acetylcholinesterase and general esterase activity was recorded in treated larvae than untreated ones. The influence of emamectin benzoate was recorded more on locomotion and enzyme activity of S. litura as compared to the remaining insecticides and the Amritsar population was least affected. Interpretation: The sublethal doses of insecticides influenced the overall behavioural physiology of S. litura and this biological parameter could be useful in designing the management strategies for S. litura. Key words: Acetylcholinesterase, Esterases, Insecticides, Locomotory behaviour, S. litura

GmERF54, an ERF Transcription Factor, Negatively Regulates the Resistance of Soybean to the Common Cutworm (Spodoptera litura Fabricius)

Soybean is attacked by various herbivorous insect pest species during the whole course of its life cycle in the field. It is important for soybean production to improve insect resistance by identifying and utilizing soybean endogenous insect-resistant genes. The ethylene-responsive transcription factor (ERF) plays a significant role in plant biotic and abiotic stresses; however, few studies focus on its role in insect resistance in soybean. Here, based on our previous common cutworm (CCW)-induced soybean transcriptome data, a soybean ERF gene GmERF54 was cloned, which responded to CCW feeding. Transcriptional analysis revealed that GmERF54 was ubiquitous in all soybean tissues and was expressed differently in insect-resistant and insect-susceptible soybean cultivars. RNA interference of GmERF54 increased the resistance to CCW, while the overexpression of GmERF54 decreased the resistance to CCW in transgenic soybean hairy roots compared with their controls. GmERF54 was localized to the nucleus, had transcriptional activation activity, and interacted with AP2/ERF GmPLT2. Several putative hormone response elements were predicted in the promoter sequence of GmERF54. Four putative elements were only found in the GmERF54 promoter sequence of insect-resistant cultivar Wanxianbaidongdou (WX), but not in the insect-susceptible cultivar Nannong 99-10 (99-10). GmERF54 promoter sequences of WX and 99-10 were cloned into the pCAMBIA1381z vector containing the β-glucuronidase (GUS) gene to generate GmERF54WX:GUS and GmERF5499-10:GUS recombinant vectors, respectively. GUS staining of soybean hairy roots containing GmERF54WX:GUS and GmERF5499-10:GUS showed that GmERF54 was induced by CCW attack and both MeJA (methyl jasmonate) and IAA (indole-3-acetic acid) treatments. Alleles in insect-resistant and insect-sensitive cultivars responded to these inductions differently. Overall, our results reveal that GmERF54 may be involved in the regulation of soybean resistance to CCW.

Evaluating, Screening and Selecting Yardlong Bean [Vigna unguiculata subsp. sesquipedalis (L.) Verdc.] for Resistance to Common Cutworm (Spodoptera litura Fabricius)

The yardlong bean [Vigna unguiculata subsp. sesquipedalis (L.) Verdc.] is an important vegetable crop, but it is prone to pest infestation. Therefore, breeding insect-resistant varieties is essential to reduce pesticide applications and to increase bean quality and yield. In the present study, 64 yardlong bean varieties were screened for their resistance to the common cutworm (Spodoptera litura Fabricius). In the greenhouse, leaves, pods, and seeds of yardlong beans were harmed by naturally occurring common cutworms. Seventeen insect-resistant and four insect-susceptible yardlong bean varieties were identified based on the weight of the nine-day-old larvae and 72 h weight increases of 4th instar larvae through feeding newly hatched and 4th instar larvae, respectively. Subsequent verification feeding experiments with newly hatched larvae showed that Zhuzaidou and Pingtangjiangdou’s insect resistance are the weakest and Jiangdou No.5, j-1, Zhijiangtezao No. 30, and Changcaidou have the strongest insect resistance. In 21 yardlong bean varieties, starch content and larval weight showed negative correlation and there was positive correlation between crude protein and larval weight, but almost neither of them reached significant levels. Through organ antibiotic and antixenotic experiments, it was concluded that common cutworms preferred feeding on yardlong bean leaves, and the weight increase of common cutworms feeding on leaves was higher than that of pods and seeds. These insect-resistant yardlong bean varieties warrant further investigation in basic antibiosis mechanism research in yardlong beans and can serve as germplasm resources for breeding programs engaged in reducing pesticide usage.

The Effect of Papaya Leaf Extract (Carica papaya L.) on the Mortality Rate of Spodoptera litura Fabricius Larvae and the Level of Damage to Soybean Leaves in Malang, Indonesia: A Greenhouse Simulation

Spodoptera litura Fabricius pest control using botanical pesticide from papaya leaves extract (PLE) is an alternative to substitute chemical pesticides. The study aimed to determine the levels of PLE's activity and evaluate the effectiveness of PLE from different altitudes (low and middle lands) and cultivars (Thailand and Indonesian) against the attack of S. litura Fabricius larvae. An experimental study with a randomized block design ( n=5 ) was conducted from December 2020 until April 2021. Each replication used 100 soybean plants and sprayed with 0% or 20% PLE of Indonesian purple cultivar low land (UR-20%), Indonesian purple cultivar middle land (US-20%), Thailand cultivar low land (TR-20%), and Thailand cultivar middle land (TS-20%), respectively and observed at 72 hours after treatment. The results demonstrate that the middle lands contained active compounds slightly higher than the lowlands. The damaged soybean leaves and intensity of soybean leaf damage are highest in control (77% and 63%) and significantly different from the treatment group, 53-60% and 29-41%, respectively. The mortality of S. litura Fabricius larvae in the control group was 11%, and in the treatment group, 47-63%. PLE from different altitudes and cultivars reduce the intensity of soybean leaf damage by S. litura Fabricius larvae.

In-Vitro Pathogenicity of Entomopathogenic Nematodes Associated Symbiotic Bacteria and their Metabolites against Armyworm Spodoptera litura Fabricius

In-Vitro Pathogenicity of Entomopathogenic Nematodes Associated Symbiotic Bacteria and their Metabolites against Armyworm Spodoptera litura Fabricius

Combined Efficacy of Biorational Insecticides against Potato Leafworm Spodoptera litura Fabricius (Lepidoptera: Noctuidae) Under Laboratory and Field Conditions

Combined Efficacy of Biorational Insecticides against Potato Leafworm Spodoptera litura Fabricius (Lepidoptera: Noctuidae) Under Laboratory and Field Conditions

Molecular characterization and toxicity evaluation of indigenous Bacillus thuringiensis isolates against key lepidopteran insect pests

BackgroundThe indiscriminate use of synthetic insecticides is not affordable and poses collateral damage to humans, non-target organisms, and environmental health. Bacillus thuringiensis (Bt) is a cosmopolitan, antagonistic soil bacterium employed as an alternative to chemical insecticides in pest management. In this study, genetic diversity and insecticidal activity of 50 indigenous Bt isolates were investigated in order to find the effective Bt isolates with a broad spectrum of insecticidal activity against lepidopteran insects.ResultsMost of the Bt isolates investigated appeared as creamy white in colour and fried egg or mucoid-type colonies having a flat or raised elevation with entire or undulated margins. Out of 50 isolates investigated, crystal shapes varied from cuboidal (40.00%), spherical (36.00%), bipyramidal (30.00%), rectangular (10.00%), and minute crystal attached to the spores (28.00%). SDS-PAGE analysis revealed that the molecular weight of the crystal proteins of Bt isolates ranged from ~ 30 to ~ 200 kDa in size. Among the Bt isolates screened, ~ 135 kDa size representing Cry1 protein was observed in 12 isolates (24.00%) and 65 kDa representing Cry2 was observed in 14 isolates (28.00%). PCR analysis was performed for cry1, cry2, cry3, cry4, cry9, vip1, vip2, and vip3 genes, which revealed the presence of cry1 gene alone in 5 isolates, and cry2 alone in 7 isolates, whereas 7 isolates were positive for cry1, cry2, and vip3 genes together. None of the Bt isolates showed the presence of cry3, cry4, cry9, vip1, and vip2 genes. Toxicity of Bt isolates was tested against four species of lepidopteran larvae, viz. Plutella xylostella Linnaeus, Helicoverpa armigera Hubner, Spodoptera litura Fabricius, and S. frugiperda Smith. Among them, 6 isolates (T29, T30, T31, T357, T381, and T388) produced 100% larval mortality against all four species of insects.ConclusionThe present study showed the diversity of Bt isolates and confirmed the significance of relentless exploration of Bt isolates for novel genes. Further investigations need to be carried out to disclose the hidden potential of these toxic isolates.

Comparative Biology of Spodoptera litura (Lepidoptera: Noctuidae) on Different Hosts under Laboratory Conditions in Pakistan

One of the most economically significant insect pests in world agriculture is the armyworm, Spodoptera litura Fabricius (Lepidoptera; Noctuidae). In 2019, S. litura was reared in a lab environment to study its biological parameters on different hosts. The sixth larval instar was recorded in this study. The period of 1st, 2nd, 3rd, 4th, 5th and 6th larval instar on cotton was 3.55±0.10, 3.59±0.09, 3.99±0.10, 4.56±0.09, 6.65±0.15, and 5.59±0.17 days, respectively. Maximum adult emergence was recorded on cabbage followed by cotton and maize. The larval length and weight were found higher on cabbage followed by cotton and maize. The pupal development was less concerning days on maize than other tested hosts. The highest mean fecundity was 2954.16 eggs per female on cabbage leaves while minimum with 987.19 eggs per female on maize leaves. The sex ratio of female to male was recorded as 1:0.7, 1:0.6, and 1:0.5, on cabbage, cotton and maize, respectively. Female was long lived than male as recorded on all tested hosts. Among all tested hosts, cabbage was recorded as the most preferable and suitable host for pest. The current study findings will provide suitable information about hosts of S. litura but suggest further studies.