Insect immunity plays a key role in defense against Bacillus thuringiensis (Bt). While the Toll/Toll-like receptor (TLR) pathway is conserved for innate immunity, its specific role in immune defense against Bt remains poorly characterized. Furthermore, the functional distinctions between the prototypical Toll/TLR subtypes - single cysteine cluster (scc) and multiple cysteine cluster (mcc) - have not been thoroughly investigated. Here, we identified 12 Toll and 12 Spätzle (Spz, the Toll ligand) genes in Spodoptera litura and classified them via genome-wide phylogenetic analysis. All SlTolls are under negative selection, with mccTolls experiencing stronger purifying selection. S. litura mccTolls are intronless genes densely clustered on one chromosome, while a subset of Spz genes (group 2 Spzs) are clustered on another chromosome. S. litura mccTolls possess more structural motifs with regular arrangements, analyses of protein-protein interaction and molecular docking revealed that mccTolls exhibit broader ligand-binding specificity. SlToll7-1 (an mccToll) and SlSpz7-1 (a group 2 Spz) were significantly upregulated in the larval midgut following exposure to Bt toxins, and SlToll7-1 interacted with SlSpz7-1. RNAi-mediated knockdown of either SlToll7-1 or SlSpz7-1 significantly suppressed the expression of antimicrobial peptide (AMP) genes and increased larval susceptibility to Bt. We demonstrate that the Toll7-1-Spz7-1 pathway in S. litura is critical for defense against B. thuringiensis. Our findings also provide evolutionary insights into the diversification of mcc- and scc-Tolls/TLRs. © 2026 Society of Chemical Industry.

Sophoridine derivatives: Synthesis, anti–Spodoptera litura activity, and plant growth–promoting effects

Insect UDP-N-acetylglucosamine pyrophosphorylase (UAP) catalyzes the formation of UDP-N-acetylglucosamine, which is a precursor of chitin synthesis. This makes UAP a promising molecular target for developing green pesticides. Inspired by a Cys334-covalent strategy, a series of maleimide derivatives against insect UAP were designed and synthesized. Enzyme activity assays revealed that all tested compounds exhibited potent inhibitory activity. Thereinto, the respective IC50 were 150 ± 10, 124 ± 26, and 108 ± 20 nM for compounds A5, A10, and A15 against SfUAP. Furthermore, time-dependent inhibition assays revealed that the IC50 of A15 decreased to 13.0 nM upon extending the incubation time to 60 min, supporting a time-dependent inhibitory profile; covalent docking simulations further corroborated a covalent binding mechanism. Bioassays demonstrated that A15 significantly inhibited the growth and development of Plutella xylostella, Spodoptera frugiperda, and Spodoptera litura. Overall, this study provides a template for designing more UAP inhibitors with covalent characteristics.

Quercetin glycosides are abundant flavonoids in apple (Malus domestica) leaves; however, how their structural variation shapes plant-insect interactions remain unclear. Here, we show that quercetin glycosylation and hydrolysis underlie a biochemical arms race between apple and multiple herbivorous insects. Herbivory by Helicoverpa armigera and Spodoptera litura activated a jasmonic acid (JA)-regulated transcriptional response that selectively induced the quercetin-glycoside pathway, resulting in elevated accumulation of 5 major quercetin glycosides. Methyl jasmonate treatment and JA content-boosting transgenic plants increased quercetin glycosides, whereas altering quercetin glycoside content did not feedback to JA signaling. Functional analyses revealed strong structure-dependent variation in anti-insect activity. Quercetin 3-O-glucoside (Q3Glc), but not its isomer quercetin 3-O-galactoside (Q3Gal), deterred larval feeding. During herbivory, apple leaves hydrolyzed Q3Glc to release toxic quercetin, while insects displayed species-specific detoxification strategies. H. armigera and S. exigua re-glycosylated quercetin to regenerate Q3Glc, neutralizing toxicity, whereas S. litura and S. frugiperda lacked this ability and suffered reduced growth. These findings reveal a reciprocal metabolic interplay in which apple activates glycoside hydrolysis to deploy toxic aglycones, while insects counter-evolve re-glycosylation to attenuate toxicity. Quercetin glycosylation patterns, therefore, serve as dynamic determinants of apple defense and herbivore susceptibility, offering opportunities for breeding insect-resistant cultivars.

Genomic exploration of Bacillus thuringiensis strain T381: Revealing its genetic potential against lepidopteran pests.

The tobacco cutworm Spodoptera litura is a globally distributed polyphagous agricultural pest and common factitious host for mass-producing biological control agents (e.g., predators, parasitoids, entomopathogens), owing to its rapid development, and high reproductive capacity. Efficient large scale rearing of S. litura is also fundamental for developing sterile insect techniques (SIT) application, which require stable, high quality insect colonies to ensure consistent sterilization outcomes and effective field release strategies. However, skewed sex ratios frequently constrain colony performance and limit the efficiency of large-scale rearing systems. In this study, seven sex ratio treatments (1:1, 3:2, 2:1, 5:2, 3:1, 7:2, 4:1) were established to quantify key reproductive traits. Among the initial ratios, 1:1 produced the highest female longevity and maximum fecundity per female. This optimal ratio was subsequently scaled to colony sizes of 20:20, 40:40, and 60:60 to evaluate proportional effects on reproductive output. Fecundity per female was highest at the 1:1 sex ratio and decreased with increasing population size. The 40:40 configuration yielded the best overall reproductive performance. These findings refine the understanding of sex ratio dependent reproductive dynamics in S. litura and provide practical guidance for improving mass-rearing efficiency both for factitious host production and for supporting SIT development.

Melatonin-dobed nano‑selenium treatment of potato plant induces direct resistance against Spodoptera litura and indirectly reshapes volatile mediated biological interactions.

Functional analysis of Sirt5 in the effect of azadirachtin on the intestinal injury of Spodoptera litura.

Species distribution modeling (SDM) is widely used to predict the spatial distribution of species. However, it faces challenges in terms of model performance and reliability because of the uncertainties associated with presence records and the representation of species absence through background points. Here, we propose a novel ensemble-based background selection method that extracts background points from areas with low habitat suitability, as identified using CLIMEX model predictions. This method was developed as an effective strategy for developing high-performance ensemble-based SDMs. We applied the ensemble method three species with different sample sizes and regional distribution patterns: the taro caterpillar ( Spodoptera litura Fabricius, 1775), the spotted lanternfly ( Lycorma delicatula White, 1845), and the red imported fire ant ( Solenopsis invicta Buren, 1972). The method was compared with traditional methods (random and bias-based approaches) using MaxEnt and Random Forest under various conditions (spatial filtering and evaluation scenarios). The ensemble-based approach minimized the uncertainty in background point selection by drawing points from areas with low predicted habitat suitability, thereby increasing the likelihood of representing true absences. The novel approach consistently outperformed the traditional methods across all evaluation scenarios. The average true skill statistic value across all conditions were 0.63 for the random selection method, 0.34 for the biased selection method, and 0.81 for the ensemble-based method, demonstrating the superior predictive performance of the ensemble approach. The model-based ensemble background selection method can be used as a practical framework for developing high-performance SDMs, ultimately enhancing the applicability of SDMs for predicting the spatial distribution of species. • The novel ensemble-based method was developed to select background points. • The ensemble method is compared with traditional methods (e.g. random and biased). • The novel approach outperformed the traditional methods across evaluation scenarios. • This study provides a framework for improving the accuracy and utility of SDMs.

Abstract Jasmonic acid (JA), a pivotal lipid-derived phytohormone, serves as a critical regulator in plant growth and defense mechanisms. However, the genetic mechanisms of OPR2 gene in JA-dependent biotic defenses of Camellia tachangensis have rarely been investigated. In this study, we performed a genome-wide association study (GWAS) to analyze 100 720 high-quality single nucleotide polymorphisms (SNPs) among 350 tea accessions from Guizhou province to identify genetic variations associated with JA. Analysis showed C. tachangensis displayed higher levels of JA content, further analysis identified 60 high-quality SNPs and 9 candidate genes related to JA. Among them, CtOPR2 encoding 12-oxophytodienoic acid reductase 2 is responsible for catalyzing the conversion of 4,5-didehydro-JA (4,5-ddh-JA) to JA. The expression level of CtOPR2 in three tea accessions with different JA content was consistent with the dynamic changes of JA content. The expression level of synthetic (AOS, AOC and ACX) and responsive (WRKY18 and MYC2) genes were significantly decreased and increased in asODN-CtOPR2-treated shoot tips and transgenic tobacco lines overexpressing CtOPR2, respectively, which were consistent with the JA content. These results further revealed that CtOPR2 gene played essential roles in promoting JA biosynthesis. A significant reduction in insect bite area was observed on transgenic tobacco leaves compared to wild-type (WT) leaves in feeding experiments with Spodoptera litura, highlighting that the positive regulatory function of CtOPR2 gene in JA-mediated immune responses. This study provides a robust theoretical foundation for marker-assisted selection (MAS) breeding in tea, aimed at developing high-JA germplasm with potentially enhanced pest resistance for cultivation in Guizhou.

The aim of this research is to determine the types of insect pests that damage rice grains (Oryza sativa. L) and how to control insect pests that damage rice plants. This research was conducted in the rice fields of Klalerek Mutin, Suco Lifau, Posto Administrativo Vemasse, Municipio Manatuto, on June 28 to July 29, 2025 with a research area of 1.3 ha. The method used by researchers in conducting research is the exploration method with the following steps: walking exploring the entire research area, to identify the types of insect pests, then the specimens found at the location were given scientific names and also took photos of the specimens as documentation. The data analysis strategy used to analyze the data through 4 ways, namely; Matching the characteristics of the original specimen with the images in the source book or through the website, identifying the morphological characteristics of the specimen and matching them with the characteristics in the source book or through the website, creating an insect pest classification system and creating an insectarium. After conducting research in the field, researchers have found 14 species from 12 families of insect pests that damage rice grains, including; namely,Acute leptocoriasis , Leptocorisa oratorius, Atractomorpha crenulata, Valanga nigricornis zehntneri, Paratenodera sinensis saussure,Oxya chinensis, Xilocopa violacea, Apiss mallifera, Lygaeus kalmia, Spodoptera Litura (F), Plutella Xylostella (L), Necrobia rufipes, Epilachna sparsa, And Senegalensis.

ABSTRACT Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) is a significant pest across tropical and temperate regions. Although present in New Zealand since the 1970s, its range and impact are expected to grow with climate change. However, little is known about its distribution or host preferences in New Zealand, particularly regarding pasture plant species. We conducted laboratory experiments to assess S. litura feeding, development, and reproduction on forage species that are increasingly favoured for pastures due to their stress tolerance, nitrogen‐fixation, or leaching mitigation abilities. The forage species tested were plantain ( Plantago lanceolata L.), chicory ( Chicorium intybus L.), red clover ( Trifolium pratense L.), and white clover ( T. repens L.). The common weed species, dock ( Rumex obtusifolius L.), was used as a positive control. Larvae were fed with cut leaves from one of the plant species to compare host quality. A second trial compared plantain, red clover, and both together. Leaf consumption, growth, and egg‐laying were monitored. Larvae consumed more dock, plantain, and chicory per day than clovers, but with lower conversion efficiencies. Larvae reared on red clover from newly hatched took an average of 4 days longer to pupate, weighed 33% less at pupation, and laid 92% fewer eggs than those fed plantain. When given a choice, neonates initially settled equally on plantain and red clover. However, early feeding on red clover resulted in persistently lower larval weights, even after switching to better hosts. These effects did not carry through to pupation. These findings highlight the importance of host plant quality for insect herbivore performance. Identification of high‐ and low‐quality host plants is a key step in mitigating the risks posed by this invasive and damaging pest. These results have important implications for pasture species selection and breeding under future climates.

Nuclear receptor HR96 regulates the overexpression of multiple detoxification genes conferring resistance to indoxacarb in Spodoptera litura.

The structural and transcriptional basis of carboxylesterase-mediated λ-cyhalothrin resistance in Spodoptera litura.

Overexpression of MtLOX24 enhances alfalfa resistance to Spodoptera litura via phenylpropanoids and jasmonic acid pathways.

Lycorine impairs Spodoptera litura fitness by inhibiting secretory phospholipase A2 expression and disrupting lipid homeostasis.

The rapid growth of the global population has increased the demand for enhanced agricultural productivity, prompting the exploration of innovative technologies such as nanotechnology for sustainable crop improvement. In this study, silver nanoparticles (AgNPs), titanium dioxide nanoparticles (TiO₂NPs), and Ag-TiO₂ nanocomposites (NCs) were synthesized using Sargassum wightii extract and evaluated for their physicochemical properties, biological activity, and environmental applicability. The synthesized materials were characterized using UV-Visible spectroscopy, SEM, EDX, XRD, and FTIR analyses, and their energy band gaps were determined from UV-Visible spectra. Seed germination assays were conducted using Kattuyanam and Co39 rice varieties under varying nanoparticle concentrations, while larvicidal activity was assessed against Spodoptera litura. Photocatalytic performance was evaluated through fast green dye degradation under light exposure. The band gap energies were determined to be 2.8eV for AgNPs, 3.56eV for TiO₂NPs, and 3.18eV for Ag-TiO₂NCs. Characterization results confirmed the successful formation, crystallinity, and purity of the synthesized nanoparticles and nanocomposites. Seed germination studies revealed significant improvements in germination percentage, root and shoot elongation, and biomass compared to controls. The Ag-TiO₂ nanocomposites exhibited pronounced larvicidal activity, achieving 96% mortality at 100µg/mL, and demonstrated high photocatalytic efficiency with up to 91% degradation of fast green dye within 5h. Overall, the findings indicate that S. wightii-mediated AgNPs, TiO₂ NPs, and Ag-TiO₂ nanocomposites possess multifunctional properties relevant to agricultural enhancement, pest management, and environmental remediation, supporting their potential use in sustainable agriculture.

Biology of Spodoptera litura (Fab.) associated with tomato crop in Mandi district of Himachal Pradesh

ABSTRACT Spodoptera litura (Fabricius), commonly known as the tobacco caterpillar, is a polyphagous lepidopteran pest that threatens over 389 plant species, including major crops like cotton, soybean, groundnut, maize and vegetables. S. litura can inflict devastating losses, reaching up to 100.00% in economically important crops. Conventional pest control primarily relies on synthetic insecticides (e.g., carbamates, organophosphates, pyrethroids), which, although effective, have raised concerns about their negative environmental, health, and resistance impacts. Thus, there is a pressing need for sustainable alternatives. The integration of selected entomopathogenic bacteria with new‐chemistry insecticides offers a promising, eco‐friendly pest management strategy against S. litura . This study investigated the combined effects of entomopathogenic bacteria Comamonas sp. (C2), Rhodococcus sp. (MG1), Planococcus sp. (KIC5) with new chemistry insecticides (Broflanilide and Cyantraniliprole) against S. litura larvae, aiming to enhance pest control while reducing chemical load. The study revealed strong synergistic effects when insecticides were alternated with KIC5 every 24 h. LC 30 Cyantraniliprole + LC 50 KIC5 resulted in 98.00% mortality ( χ 2 = 13.23), while LC 30 Broflanilide + LC 50 KIC5 achieved 100.00% mortality ( χ 2 = 11.84). These combinations also caused the highest genotoxic effects. Overall, integrating and alternating chemical and microbial control help to reduce insecticide load, lower environmental and health risks, protect beneficial insects and delay resistance development.

This study discusses the synthesis and structural characterization of a new series of benzofuran-pyrazole cyanoacrylamide derivatives 3a–f and 5 utilizing spectroscopic analyses involving IR, NMR, and ESI-MS spectrometry. The insecticidal activity of benzofuran-pyrazole cyanoacrylamide derivatives 3a–f and 5 against Spodoptera littoralis and Tribolium castaneum was evaluated. The benzofuran-pyrazole cyanoacrylamide derivatives on Spodoptera littoralis and Tribolium castaneum revealed that 3b, 3c, and 3a were the most effective compounds, respectively, while compounds 3d, 3e, 3f, and 5 were not lethal to S. littoralis. The LC50 values for compounds 3b, 3c, and 3a were 79.58, 106.37, and 226.17 ppm at 72 h, respectively; while in contrast, compounds 1, 3d, 3e, 3f, and 5 exhibited very low or no contact toxicity against T. castaneum. Density Functional Theory (DFT) calculations were employed to compare the E/Z stereoisomers. The E isomers of 3a, 3c, 3d, and 3e exhibited lower energy gaps, higher softness, and greater electrophilicity, with 3c.E emerging as the most reactive candidate. In contrast, compounds 3b, 3f, and 5 favored the Z configuration, showing improved orbital overlap and higher dipole moments. These findings confirm that stereochemistry strongly influences electronic structure, reactivity, and potential adsorption behavior. In addition, a computational evaluation was conducted to assess the potential of novel benzofuran-indazole hybrid compounds (3a, 3b, 3c) as insecticidal agents targeting acetylcholinesterase (AChE) from two major pests: Spodoptera litura (tobacco cutworm) and Tribolium castaneum (red flour beetle). Molecular docking revealed that all three compounds exhibited strong binding affinities (ranging from − 8.0 to − 8.8 kcal/mol) to both insect AChEs, comparable to or surpassing the positive control (carbaryl) and co-crystallized inhibitor (NAF). The binding modes involved key interactions with catalytic and peripheral anionic site residues, facilitated by hydrogen and hydrophobic bonds. Compound 3b consistently showed among the highest affinities. Subsequent molecular dynamics simulations of the 3b-AChE complexes confirmed stable binding, with minimal perturbation to protein backbone stability, maintained compactness, and persistent intermolecular hydrogen bonds. ADMET predictions indicated that the compounds generally comply with drug-likeness rules. Toxicity risks (mutagenic, tumorigenic) were predicted to be low. Overall, the in silico analyses identify these hybrid compounds, particularly 3b, as promising, stable, and specific AChE inhibitor leads for the development of novel insecticides.