Bioinsecticides have gained attention as a sustainable and eco-friendly alternative to traditional chemical insecticides. They are target-specific, biodegradable, and reduce the development of insect resistance. However, their use is often limited by environmental instability, particularly under sunlight and UV radiation, which rapidly degrade active ingredients and reduce efficacy. Protective formulation, such as addition of UV-screening agents are needed to improve their durability and efficacy. This study investigates the efficiency of three UV protectants, Octylpalmitate, Tinuvin P, and UV- P in enhancing the persistence of some biocontrol agents, Dipel DF, Tracer, and Diacox under field conditions for 15 days to control the 4th instar larvae of Spodoptera littoralis. After 12 days, the residual effect of the all insecticides had markedly decreased, with Tracer showing the lowest persistence with zero mortality, and Diacox + UV protectant the highest. By 15 days, the sustained efficacy was absent, except for Diacox mixed with Octyl palmitate, Tinuvin P, and UV-P, which still caused 27, 32 and 12% mortality; respectively. The SDS-PAGE of S. littoralis larvae following 15 days of treatments revealed differences in the numbers of protein fragments between treated and control. New protein bands formed in the treated samples, while several normal bands disappeared.

Genomic characterization of an Anticarsia gemmatalis multiple nucleopolyhedrovirus isolate from the cotton leafworm, Alabama argillacea with cross-species infectivity potential for pest management.

Plants can perceive specific elicitors in the oral secretions (OS) of herbivorous insects and respond by increasing their defences. Whether plants can discriminate among similar herbivorous insect species and differentially modulate their defence responses against them is largely unknown. Here, we investigated the responses of the maize transcriptome, phytohormones, and volatile emissions to the OS of three closely related Spodoptera caterpillars: the fall armyworm S. frugiperda, the beet armyworm S. exigua, and the cotton leafworm S. littoralis. Maize plants strongly increased their phytohormone levels and volatile emissions when treated with each of the OS, which was reflected in the transcription levels of genes involved in phytohormone signalling, and primary and secondary metabolism. Compared to the OS of S. exigua and S. littoralis, the secretion of the maize specialist S. frugiperda, elicited greater changes in the maize transcriptome but triggered considerably lower volatile emissions. Besides revealing the generality and specificity of maize responses to different lepidopteran caterpillars, the dataset provides a molecular resource for studies that aim to identify and characterise herbivore-specific elicitors and effectors and their receptors. This information can then be used to elucidate and possibly disrupt the mechanisms that allow well-adapted herbivorous insects to manipulate maize defences.

Abstract Background Severe climatic events, such as heat and cold waves, can influence the dynamics of pest-pathogen interactions. Fungal efficacy among noctuid pests may be bidirectionally influenced by thermal waves. Therefore, this study aimed to investigate how extreme temperatures influence fungal efficacy against the Egyptian cotton leafworm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) under laboratory conditions. Results After infection with LC 50 of the entomopathogenic fungi, Beauveria bassiana or Metarhizium anisopliae , third instar larvae were exposed to a simulated heat wave (35 °C) or cold wave (15 °C) for five consecutive days, with 25 °C serving as the control. Developmental parameters, adult emergence, reproductive success, and immune responses through phenol oxidase activity and hemolymph protein content were evaluated. Results indicated that concomitant temperature and fungal infection significantly influenced larval weight gain, pupation rate, and time, developmental time, as well as egg hatchability. The weight gain decreased as the temperature increased, whereas the pest developed faster in heat or at normal temperatures. Cold waves led to a notable rise in pupation rates compared to heat waves or normal temperatures. The infection by M. anisopliae adversely affected the pupation rate, emergence, and egg hatchability in comparison to B. bassiana , particularly under thermal stress conditions. Moreover, both thermal waves and fungal infections led to a decrease in phenol oxidase activity in larval hemolymph, indicating impaired immunological responses, with M. anisopliae more than B. bassiana . Conclusion The present findings highlight the link between climatic stressors and biocontrol agents, stressing the necessity of incorporating environmental variability into pest management systems. Timing fungal applications under thermal stress could boost biocontrol and reduce chemical pesticide use.

Antifeedant activities of some plant secondary metabolites on cotton leafworm (Spodoptera littoralis (Boisduval, 1833)) (Lepidoptera: Noctuidae)

In this study, we create novel imidazoles containing ciprofloxacin moieties that have demonstrated potent insecticidal activity. The synthesis was finished using a one-pot method involving imidazoles 3a-f, formaldehyde, and ciprofloxacin. Furthermore, pyrazoles 11 and 12 were produced by the successful addition of benzothiazole and benzoxazole derivatives to the procedure. According to the data, all of the products that were tested demonstrated insecticidal efficacy against both Spodoptera littoralis larval instars, with adjustable levels. With LC50 value of 4.55mg/L against larvae in their second instar, compound 6 was the most toxic of all. The target goods were tested on cotton leafworm larvae in their second and fourth instars. In an additional attempt to marginally expand insecticidal materials, the latent effects of the examined prepared materials were evaluated on a variety of biological parameters, including adult longevity, pupal weight, proportion of normal and deformed pupae, adult emergence, fecundity, and egg hatchability. Additionally, using compound 6 to treat the fourth S. littoralis larvae showed significant alterations in biochemical examination, including acetylcholinesterase, adenosine triphosphatase (ATPase), glutathione S-transferase (GST), CaE, and total protein. These results provide insightful information about the continuous global search for more modern and efficient methods to manage insect resistance.

<b>Background and Objective:</b> The Egyptian cotton leafworm, scientifically named <i>Spodoptera littoralis</i>, is a major economically important pest that causes extensive economic losses across Africa, particularly in Egypt. The current study aimed to estimate the effects of lufenuron and hexaflumuron on the survival potential, development, metamorphosis and main metabolites of this economically important insect pest. <b>Materials and Methods:</b> Penultimate instar larvae were treated with four concentrations (250, 500, 1000 and 2000 ppm) of lufenuron and hexaflumuron using a leaf-dipping technique on fresh castor bean leaves. Mortality, development time, pupation and metabolite contents were monitored across early-, mid- and late-aged larvae. Major metabolites (proteins, carbohydrates and lipids) were analyzed using standard biochemical assays. Statistical analysis was performed to determine concentration-dependent effects and significance was evaluated at the appropriate confidence level. <b>Results:</b> The obtained results revealed that treatment with the highest concentration resulted in complete larval mortality for both compounds. Other concentrations recorded a concentration-dependent increase in larval mortality, with severe mortality observed during the early days after treatment. Both lufenuron and hexaflumuron induced pronounced negative effects on larval growth and developmental rates, regardless of the concentration level or the targeted larval age. Pupation percentages were also affected; higher concentrations induced complete pupation failure. A disturbance in the main body metabolites of the penultimate instar larvae was also recorded across early-, mid- and late-aged larvae. The total main metabolite content was drastically disrupted, regardless of the tested compound or the larval period. <b>Conclusion:</b> Lufenuron and hexaflumuron have a potent effect in curbing the cotton leafworm, <i>S. littoralis</i> and a strong effect on disrupting its vital and physiological processes.

Objective: The overreliance on chemical insecticides for controlling the devastating cotton leafworm, Spodoptera littoralis, has led to resistance and environmental concerns. This study investigated the biocontrol potential of the entomopathogenic fungus Beauveria bassiana by determining its median lethal concentration (LC₅₀) against fourth instar larvae and characterizing the ensuing histopathological damage to the larval cuticle, the primary barrier to infection. Methods: The pathogenicity of an indigenous B. bassiana isolate was assessed through a leaf-dipping bioassay using five conidial concentrations (1×10⁵ to 1×10⁹ conidia/mL). The LC₅₀ was calculated via probit analysis. For histopathological examination, larvae treated with the LC₅₀ (2.81 × 10⁶ conidia/mL) were dissected at 72 hours post-treatment. Cuticle samples were processed, embedded in paraffin, sectioned, and stained with Hematoxylin and Eosin (H&E) and Periodic Acid-Schiff (PAS) for detailed microscopic analysis. Results: Bioassay results revealed a significant dose-dependent mortality, with the highest concentration (1×10⁹ conidia/mL) causing 85.3% mortality. The calculated LC₅₀ was 2.81 × 10⁶ conidia/mL. Histopathological analysis demonstrated severe structural degradation in the cuticle of treated larvae. Key findings included the disintegration of the epicuticle and the lamellar structure of the procuticle, extensive invasion and proliferation of fungal hyphae and blastospores within the cuticular matrix, and the formation of lytic cavities. Fungal penetration reached the epidermal layer, which displayed significant disruption and vacuolization, confirming a complete breach of the host's primary physical defense. Conclusion: Beauveria bassiana proves to be a highly virulent pathogen against S. littoralis larvae. The histopathological evidence provides a mechanistic understanding of its efficacy, directly linking larval mortality to comprehensive cuticular disintegration and systemic fungal invasion. These findings strongly support the integration of B. bassiana as a sustainable and effective biocontrol agent within IPM programs to manage this economically important pest.

Cotton leafworm, Spodoptera littoralis (Boisd.) is a major lepidopteran pest of beet types in Egypt. The present investigation was conducted to determine the effect of three beet types; sugar, table and fodder beet on feeding S. littoralis in addition to the toxic effects of three insecticides, Protecto 9.4% WP (Bacillus thuringiensis), Speedo 5.7 % WG (emamectin benzoate) and winsor 24% SC (methoxyfenozide) under semi-field conditions. This study was carried out in 2023 and 2024 seasons, at Sakha Agricultural Research Station. Results revealed that the lowest area of the leaf consumed by S. littoralis after 24 h was significantly recorded in both fodder and sugar beet type treatments; it was 1.10 and 1.29 cm2 /larva, respectively. Feeding percentage rate of 4th instar S. littoralis larvae fed on different beet leaves treated with Protecto, Winsor and Speedo at 1/2 and 1 field rates was decreased. At 1/2 recommended rate after 24 h, the lowest area of the consumed leaf and feeding percentage were significantly recorded in Speedo treatment on table beet 0.59 cm2/ larva and 2.99%, respectively. Based on the nutritional values of testing beet types, results proved that table beet was the most favorable type for S. littoralis due to the differences in the leaf nutritional quality and low level of total phenol in the leaves of table beet. This research aims to determine the most effective and sustainable method for controlling S. littoralis by comparing the tolerance of different beet types with the efficacy of various insecticides.

Abstract This study investigated the chemical composition of Plectranthus amboinicus essential oil and their impact on the Egyptian cotton leafworm, Spodoptera littoralis, an herbivorous lepidopteran insect. Accordingly, twenty‐eight compounds (96.8%) were found comprising monoterpenes and sesquiterpenes made up 39.34% and 56.82% of the mixture, respectively. Among the monoterpenes, carvacrol (19.38%) and O‐cymene (8.22%) represent the main components, whereas the main components of sesquiterpenes were τ‐muurolol (13.08%) and isospathulenol (7.52%). Further, substantial malformations were observed in both the pupal and adult stages at the applied concentrations which did not impact adult survival rate, however the survival rate of pupae was significantly lower at 75 mg/L. The findings elucidate the effects of P. amboinicus essential oil on moths, especially S. littoralis, presenting a viable method to reduce reliance on synthetic chemical insecticides and promote the adoption of natural substances for pest control. Molecular docking was used to evaluate the binding of 28 identified phytochemicals to N‐acetylglucosamine kinase (NAGK, PDB ID: 2CH5), an important enzyme for the chitin metabolism of S. littoralis. Longifolol, humulene, and terpinen‐4‐ol showed potent inhibition of NAGK, surpassing the co‐crystallized ligand. Therefore, the optimization of these compounds may lead to the development of effective, environmentally friendly insecticides for S. littoralis.

BackgroundThe Egyptian cotton leafworm (Spodoptera littoralis) is a highly destructive, pesticide-resistant pest affecting over 80 economically important crops across the Mediterranean and African regions. While chemical insecticides offer temporary relief, their long-term use poses environmental and health risks, and resistance development reduces their effectiveness. Biological control using entomopathogenic fungi, particularly Trichoderma spp., offers a sustainable alternative. Traditionally, it is used against plant pathogens, Trichoderma harzianum, T. viride, T. asperellum, and T. longibrachiatum have also shown insecticidal potential through the production of compounds like peptaibols, gliotoxins, and chitinases, and by inducing systemic resistance in plants. However, the entomopathogenic potential of native Trichoderma isolates in Egypt remains undiscovered, and field performance is often inconsistent. This study aims to identify and evaluate native Trichoderma strains against S. littoralis and enhance their biocontrol efficacy through interspecific protoplast fusion a promising parasexual technique for strain improvement.ResultsMultilocus sequence analysis targeting the tef1-α and rpb2 genes identified the isolates as T. harzianum, T. asperellum, and T. longibrachiatum. Phylogenetic analysis clustered the isolates into three well-distinctive clades corresponding to these species. Among the tested isolates, Tricho19 (T. longibrachiatum), Tricho5 (T. asperellum), and Tricho30 (T. harzianum) demonstrated the highest extracellular chitinase activity and larval mortality in oral bioassays against S. littoralis. Interspecific protoplast fusion led to the generation of fusants with significantly enhanced chitinase production and insecticidal activity relative to their parental strains. Greenhouse assays confirmed the superior performance of fusant Fus8, which exhibited the highest larval mortality and antifeedant activity, closely approaching the efficacy of a chemical insecticide.ConclusionInterspecific protoplast fusion significantly improved the entomopathogenic performance of Trichoderma strains against S. littoralis. The enhanced activity of fusant strains, particularly Fus8, highlights the potential of this cost-effective strategy to generate improved biocontrol agents. These findings contribute to the development of sustainable pest management alternatives that can reduce reliance on chemical pesticides in agriculture.

Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is a major insect pest that severely affects various crops. Our study provides new insights by combining field efficacy trials with enzymatic analysis to evaluate the effects of emamectin benzoate mixtures with other insecticides (lufenuron, cypermethrin, chlorpyrifos, and spinosad) against S. littoralis. The aim of our work was to investigate the effectiveness of five insecticides, i.e., emamectin benzoate, lufenuron, cypermethrin, chlorpyrifos, and spinosad, for controlling this pest under field conditions during two consecutive seasons (2023-2024). Each insecticide was applied individually at the recommended rate, while some were mixed with emamectin benzoate at half its recommended rate. The results indicated that emamectin benzoate was the most effective insecticide, followed by lufenuron. The joint action of emamectin benzoate (LC25) and its mixtures with other insecticides (chlorpyrifos, spinosad, cypermethrin, and lufenuron) at various concentrations (LC50) against second- and fourth-instar S. littoralis larvae was evaluated. Results showed additive effects with chlorpyrifos, lufenuron, and cypermethrin, while potentiation occurred with cypermethrin (LC50) and chlorpyrifos (LC50). Antagonistic effects were observed in the combination of emamectin benzoate with spinosad (LC25 and LC50). This study concluded that applying insecticides individually is more cost-effective for managing cotton leafworm infestations in cotton crops. Additionally, enzyme activity analysis showed significant changes in alpha-esterase, beta-esterase, carboxylesterase, acetylcholinesterase, and glutathione S-transferase levels in larvae treated with different insecticide combinations.

Barbiturate and uracil scaffolds as potential insecticidal agents: Synthesis, DFT studies and in vivo Biochemical Susceptibility of the polyphagous pest, cotton leafworm, Spodoptera littoralis (Lepidoptera: Noctuidae)

Native mid-gut bacterial community increases resistance to nucleopolyhedrovirus in the cotton leafworm.

Inter-plant signalling effects on cotton defences are shaped by the joint effects of emitter herbivore load and soil salinity stress, with latter strengthening such effects on direct defences but weakening those on indirect defences. Volatile-mediated plant-to-plant signalling in response to herbivory is well documented, but its contingency on abiotic factors and variation in herbivore load is poorly understood. To address this gap, we investigated how soil salinity levels and herbivore load may influence signalling effects on plant defences and resistance in wild cotton (Gossypium hirsutum), using the specialist herbivore Alabama argillacea (cotton leafworm). We conducted a greenhouse experiment where plants were grouped in triplets: one acting as the emitter and the other two as receivers. Each triplet was placed inside a mesh cage. Both emitters and receivers were exposed to either ambient (control) or augmented soil salinity. Emitters at each salinity level underwent three treatments: no damage, damage by one or three caterpillars. After 48h of damage, we collected VOCs from the emitters, which were removed from the cages at 72h. Afterwards, we damaged the receiver plants to test for the priming effects on the induction of extrafloral nectar (EFN) and terpenoid aldehyde content, as well as on resistance to herbivory. Herbivory increased VOC emissions significantly under high herbivory load, but salinization reduced this effect. Receivers exposed to VOC from plants with high herbivore load induced a greater EFN concentration compared to those exposed to control emitters, an effect that disappeared under augmented salinity. Soil salinity did not affect thesignalling effecton terpenoid aldehyde content but did influence herbivore resistance. These findings suggest that signalling depends on herbivore load and soil salinity, with the latter enhancing or affecting the induction depending on the plant defense traits.

Cotton (Gossypium spp.) (Malvaceae) played a fundamental role in the agricultural economy of São Paulo, Brazil, during the late 19th century, significantly contributing to regional industrialization and economic growth. However, large-scale cotton cultivation also facilitated the proliferation of pests, particularly the cotton leafworm, Alabama argillacea (Hübner, 1823) (Insecta, Lepidoptera, Erebidae), which caused significant economic losses. This study examines the historical documentation and entomological significance of a specimen of A. argillacea collected in 1899 in Tatuí, São Paulo, southeastern Brazil, which is currently housed at the Museu de Zoologia da Universidade de São Paulo. The preservation of this specimen, coupled with contemporary scientific efforts, illustrates the growing intersection between entomological research and agricultural practices at the time. An official correspondence from the mayor of Tatuí to the director of the Museu Paulista in 1899 underscores early efforts to integrate museum-based entomology into pest management. The historical specimen offers a valuable opportunity for future museomic studies, allowing comparisons between past and contemporary A. argillacea populations and potentially revealing genetic shifts resulting from agricultural intensification and climate change. Furthermore, this research highlights the enduring role of natural history collections in documenting biodiversity, informing pest control strategies, and contributing to sustainable agricultural practices.

Efficacy of Chemical and Bio-Rational Insecticides Against Cotton Leaf Worm (Spodoptera littoralis) in Soybean

Coumarin-6-sulfonyl derivative: a novel antimicrobial candidate and agriculture control of strawberry black root-rot and cotton leafworm

Biological and molecular characterization of Spodoptera littoralis granulovirus with insecticidal activity against the cotton leafworm, Spodoptera littoralis (Boisd.)

BackgroundBeauveria bassiana is one of the most renowned entomopathogenic fungi and has recently been recognized as a potential biopesticide for a wide range of insect pests. The secondary metabolites of B. bassiana are believed to contribute to its pesticidal activity. Meanwhile, the Egyptian cotton leafworm, Spodoptera littoralis, is a significant pest that causes considerable damage to various key crops.ResultsIn this study, secondary metabolites were extracted using ethyl acetate from both the culture medium filtrate and the mycelia separately. Subsequently, the extracts were separated via thin-layer chromatography into six fractions from the medium filtrate (F0:F5) and ten fractions from the mycelia (M1:M10). All fractions were assessed for their insecticidal effects on second instar larvae of S. littoralis. The treatment of F0 resulted in the highest larval mortality rate of 61.11%, followed by M3 with a mortality rate of 45.19%. M2 and M8 had similar effects, each resulting in a mortality rate of 40.00%. Furthermore, scanning electron microscopy revealed cuticle disorders and deformations in larvae treated with all treatments. Fractions exhibited the highest mortality rates in S. littoralis larvae, and the total injuries were analyzed using GC/MS, which revealed the presence of eight bioactive compounds. Notably, this study represents the first detection of 2,4-di-tert-butylphenol in the mycelia of B. bassiana, a compound known for its high toxicity. In addition, other compounds contributed to the observed experimental results.ConclusionThese findings indicate that B. bassiana could serve as a sustainable source of bioactive metabolites with significant insecticidal effects on S. littoralis. This suggests a strong potential for improving integrated pest management (IPM), particularly when large-scale production is implemented.Graphical abstract