Green synthesis, computational approaches, and bio-efficacy of novel triazines as insect growth regulator (IGR) analogues against spodoptera littoralis (Boisd.)

Characterization and Evaluation of Some Actinomycetes Isolates from Egyptian Soils against Spodoptera littoralis and Fusarium oxysporum

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.

Impact of magnetic fields on the entomopathogenic activity of Beauveria bassiana and the biological and biochemical responses of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)

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.

Ilicic acid, nerolidol, and 9-hydroxynerolidol are major components of the aerial parts of Dittrichia viscosa. These components were selectively isolated in multigram quantities and used as lead compounds to generate diversity in the search for new natural-product-derived pesticides. A total of 29 derivatives of these three molecules—some of which are known natural products—were generated by subjecting these natural products to different transformations. In order to explore potential applications in sustainable biocontrol, some of the compounds generated were evaluated for plant protection potential against insect pests (Spodoptera littoralis, Myzus persicae, Rhopalosiphum padi), against the nematode Meloidogyne javanica, and for their phytotoxic effects on ryegrass (Lolium perenne) and lettuce (Lactuca sativa). Additionally, their effects against the tick Hyalomma lusitanicum have been tested. Compound 11 was found to be antifeedant against S. littoralis and nematicidal. Compounds 3a and 8 were potent antifeedants against R. padi. None of the tested compounds significantly inhibited lettuce growth, and compounds 17, 3, and 3a even promoted root development. Conversely, compounds 3, 4, 11, 17, and 21a exhibited strong herbicidal activity on ryegrass. In larvicidal assays against H. lusitanicum, compounds 3, 3a, 11, 17, 29, and 33 were active, with compound 29 being six times more active than the positive control nootkatone.

This study was conducted in 2024-2025 in the laboratories of Ege University, Faculty of Agriculture, Department of Plant Protection. Spodoptera littoralis (Boisduval, 1833) (Lepidoptera: Noctuidae) is an important pest in Türkiye and causes extensive economic losses in many cultivated crops. During our field observations, some blackening and dead individuals were observed in Leptinotarsa decemlineata (Say, 1824) (Coleoptera: Chrysomelidae) larvae. As a result of the isolations made from blackened larvae and plant samples, 6 different bacterial isolates were obtained. Pseudomonas fluorescens Migula (Pseudomonadales: Pseudomonadaceae) strain 184, whose entomopathogenic effect was proven in our previous studies and molecular diagnosis and sequence analysis were performed, was also used in these tests. As a result of two seperated experiments, it was observed that endophytic bacteria isolates caused 20 to 93% mortality compared to untreated negative control. As a result of conventional and molecular identification and sequence analysis, the bacterial isolates with the highest entomopathogenic effect against S. littoralis larvae were isolates 441 and 442, which were definitively identified as Serratia marcescens J. and Enterobacter cloacae M. (Enterobacterales: Enterobacteriaceae), respectively. This study revealed that these bacteria may have potential for biological control against S. littoralis.

It is very desirable to develop new pesticide lead compounds to reduce the increasing resistance in agricultural pests caused by the widespread usage of agrochemicals. This study assessed the synthesis of novel hydrazones and heterocycles as potential pesticidal agents. The pesticidal efficacy of the synthesized compounds was assessed against Tetranychus urticae (Koch) and Spodoptera littoralis (Boisd.). Amongst the tested derivatives, compounds 3, 4, 10, 12, 13, 16, and 17 exhibited outstanding activity against 4th instar larvae of S. littoralis and adult females of T. urticae. The effect of the promising derivatives on some key enzymes of both pests clarified the mode of action of the outstanding derivatives. A molecular docking study was performed for the synthesized compounds against AChE and GST targets, which revealed the good affinity between the tested compounds and the target proteins in comparison with reference ligands. In addition to identifying promising pesticidal candidates, this study provides a robust framework for developing next-generation pest management techniques that tackle resistance issues and promote sustainable agricultural practices.

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.

Sublethal effects of broflanilide and isocycloseram on Spodoptera littoralis and associated natural enemies

The widespread use of rare earth elements (REEs) in agriculture, particularly Lanthanum (La), raises concerns about their ecological impact on non-target organisms. We investigated the direct and indirect effects of La on the insect pest Spodoptera littoralis and its host plant, Brassica rapa. Direct exposure to La-supplemented diets reduced larval growth, survival, and egg production. Interestingly, a transgenerational effect was observed, where larvae from La-exposed parents exhibited increased resilience, showing no performance reduction on the same diets. Indirectly, La accumulation in plants mediated a hormetic response in herbivores, increasing larval weight at low concentrations but reducing it at high concentrations, while modulating their oxidative stress and detoxification gene expression. From the plant perspective, La exposure amplified herbivory-induced calcium signalling and altered the expression of key genes related to calcium and reactive oxygen species pathways. These findings reveal the complex ecological risks of La accumulation in agroecosystems, affecting both plants and insects directly and through novel transgenerational effects.

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.

RNAi-mediated suppression of embryos as a promising strategy to control Spodoptera littoralis

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.

Effect of four host plants on biological characteristics of Spodoptera frugiperda and Spodoptera littoralis (both Lepidoptera: Noctuidae)

Plants interact complexly with herbivores and diverse microbial communities, both plant-associated and insect-associated. A recent study investigated how the endophytic fungus Trichoderma, colonizing tomato plants, affects the herbivore Spodoptera littoralis. The study revealed that Trichoderma-enhanced plant resistance significantly reduced larval performance by profoundly changing the insect's gut microbial community composition. This work demonstrates that the effects of plant fungal colonization on insect herbivores are critically mediated by the insect's gut microbiota, highlighting a key mechanism in plant-insect-microbe tripartite interactions with implications for sustainable pest management.

Tomatoes are one of the most popular vegetables. The high level of production in the world is often offset by numerous losses that occur during production in the field or in the post-production stages. Preservation in its fresh form is a challenge, particularly due to pest attacks on stored food. A promising natural and inexpensive solution to protect against pests is the use of chitosan (CH), which can be associated with essential oils (EOs) with repellent effects. In previous studies, some protective effects have been demonstrated using chitosan films coated with EOs. In this study, we tested CH-EOs associations on tomato fruits to evaluate their efficacy against attacks by the pest Spodoptera littoralis (Boisduval, 1833), taking into account parameters such as age and body mass of the larvae and the effect over time (10 days) of the treatments. Our study highlights the potential of the combination of CH and cinnamon EO as an environmentally friendly solution to protect tomatoes from S. littoralis attack. Here we found a repellent effect of cinnamon EO combined with CH on S. littoralis larvae, with no effect on larval attractiveness or repellence for CH alone and the four other EOs tested. The main compound in cinnamon EO, (E)-cinnamaldehyde, had no overall repellent effect on larvae, but had specific effects when larval age, body mass, and post-treatment time were taken into account.

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