Search Results (81)

The increasing resistance of agricultural pests and disease-vectoring arthropods to synthetic pesticides underscores the urgent need for novel and sustainable biocidal agents. This study evaluates, for the first time, the insect antifeedant and ixodicidal activities of essential oils derived from ten Amazonian Piper species and their major constituents. Antifeedant effects were assessed against Spodoptera littoralis, Myzus persicae, and Rhopalosiphum padi, whereas ixodicidal activity was tested on Hyalomma lusitanicum. Additionally, the effects of these oils on the plant-parasitic nematode Meloidogyne javanica were investigated. Essential oils from Piper mituense (51.6% apiol) and P. sancti-felicis (76.1% apiol) exhibited the highest bioactivity, achieving more than 75% feeding inhibition across all insect species and 100% tick mortality. P. mituense consistently demonstrated greater potency, suggesting possible synergistic interactions among its minor constituents. Principal component analysis linked apiol-rich chemotypes with broad-spectrum activity. In contrast, oils rich in oxygenated caryophyllene derivatives, particularly those from P. casapiense, showed strong selective antifeedant effects against R. padi. Pure apiol displayed activity across all assays, whereas no nematicidal effects were observed. Molecular docking analyses supported these findings, indicating that apiol can interact with acetylcholinesterase in addition to its known effect on cytochrome P450 targets. Overall, these results identify complementary Piper chemotypes with promising potential as dual-purpose biopesticides for integrated pest management strategies. Full article

Spodoptera littoralis (Boisduval, 1833) is one of the most destructive insect pests in Egypt and worldwide. This study was conducted to investigate the impact of exposure to a magnetic field (MF) of 180 milliTesla on the developmental phases of S. littoralis, as well as malform, reproductivity, and genomic DNA mutagenicity. The obtained results concluded that the exposure of S. littorelis to MF significantly affected the malformation and mortality rates in both larvae and pupae. The MF extended the duration of the pupal stage from approximately 0.8 to 5.9 days compared to the untreated pupae. The adult emergence percentages decreased to 68.0 and 74.0% upon exposure to a magnetic field for 60 and 40 min, respectively. The female fecundity decreased by increasing the exposure duration, yielding (7–10), (6–10), and (3–8) mass eggs per female upon exposure intervals of 20, 40, and 60 min, respectively. Meanwhile, the hatchability percentage diminished with prolonged exposure time, recording 77%, 60%, and 53% for MF exposure durations of 20, 40, and 60 min, respectively, compared to 91% hatchability in the control trial. The genetic characterization employing inter-simple sequence repeat (ISSR) markers disclosed genetic mutagenicity, exhibiting a similarity matrix range from 61.6% to 74.1% for larvae, 59.8% to 68.5% for adults, and 36.2% to 49% for pupae, indicating genetic alteration in treated insects. Hence, these findings highlight the implications and prospective application of a magnetic field of 180 milliTesla as a unique approach in integrated S. littoralis control frameworks. Full article

Plant genotypes can vary in multiple functional traits due to adaptation to heterogenous environments. However, whether such variation can extrapolate to effects on soils and further on performance of subsequent plants, thus generating a genotypic variation in soil legacy, remains unclear. In this study, we studied how plant genotypic variation impacts soil legacy when exposed to aboveground insect herbivores. We used 11 wild genotypes of woodland strawberry (Fragaria vesca L.) experimentally exposed to leaf beetles (Galerucella tenella) to condition live soil. We then replaced the conditioning plants with naïve plants to examine soil legacy effects on growth and resistance on the subsequent plant genotype (referred to as the focal genotype) against the generalist herbivore Spodoptera littoralis. This allowed us to test the extent to which plant genotypic variation in soil legacy is altered by aboveground herbivory. We found an overall positive soil legacy effect of woodland strawberry, indicated by 69.9% higher belowground biomass of the subsequent focal genotype grown in conditioned soil compared to in unconditioned soil. We also observed a genotype-dependent soil legacy effect on performance of S. littoralis indicated as relative growth rates reduced by 37.9% on the subsequent focal genotype in soil conditioned by the focal genotype itself compared to by other genotypes, though the legacy effect was cancelled out when conditioning genotypes were exposed to G. tenella herbivory. A genotypic variation was further detected in soil legacy on the efficiency of conversion of ingested food by S. littoralis caterpillars feeding on the focal genotype. However, the genotypic variation was only present when the focal genotype was excluded from the conditioning genotypes at the exposure of G. tenella herbivory. Collectively, our study shows a conditional plant genotype-dependent soil legacy effect on herbivore resistance (measured as herbivore performance) rather than on plant growth, and the magnitude of the legacy effects depends on both the identity of the conditioning genotypes and the measures of the herbivore resistance. The findings of this study provide new insights into how plant genotypes or herbivory affects soil feedback on plant growth and herbivore resistance. Full article

Today, interest in natural remedies for biocontrol of crop pests is paramount. Punica granatum L. (pomegranate) is studied worldwide to obtain interesting bioactive compounds. Its anti-parasitic activity is associated with the presence of alkaloids in its roots. In this work, we explored the possibility of obtaining from P. granatum roots pelletierine-like alkaloids, which were extracted, characterized, isolated and used for the biocontrol of pests such as Spodoptera littoralis, Myzus persicae, Rhopalosiphum padi and Meloidogyne javanica. Two different extracts were obtained, characterised and quantified by GC-MS and LC-ESI-HRMS. In vitro assays of nematicidal activity were performed comparing the extracts with isopelletierine and pseudopelletierine as pure molecules. The results of these assays showed a difference in activity between iso- and pseudopelletierine, especially in terms of the nematocidal effect against M. javanica with isopelletierine being more active than pseudopelletierine. This leads us to conclude that only extracts from P. granatum roots with a high concentration of isopelletierine alkaloid can be used in effective pest control products. Full article

The natural product composition of the hexane and methyl tert-butyl ether extracts of Dittrichia viscosa roots was examined. Eight terpenoids were identified by nuclear magnetic resonance (NMR) and high resolution mass spectroscometry (HRMS) techniques, four of which (1, 5, 6 and 8) are reported here for the first time as natural products. Of these eight compounds, four are thymol derivatives (1–4), two are guaianolides (5 and 7) and two are himachalanes (6 and 8). Additionally, the occurrence of himachalanes in this species is reported for the first time. Furthermore, a study of the potential plant protection effects of some of these natural products and the chemical derivative 6a was carried out. Promising preliminary results were obtained for compounds 1–3 and 6a as antifeedant agents against Spodoptera littoralis; 1–3 and 5 against Myzus persicae; 1–3 against Rhopalosiphum padi; and 4 as nematicide against Meloidogyne javanica. Finally, the phytotoxic activity of compounds 4, 5 and 6a against the monocotyledonous species Lolium perenne was also proven. Full article

Banana (Musa spp.) is an economically important crop whose relevance is steadily increasing in greenhouse-based production systems. This study aimed to determine pest and natural enemy species, and pest population densities in greenhouse banana fields in the Western Mediterranean Region of Türkiye. Periodic studies were conducted every 15 days in 2.4 hectares for two consecutive years (2022–2023), while nonperiodic studies covered 128.9 hectares. Species were collected through visual inspection, sticky traps, and plant sampling. Seventeen pest species from four orders and eight families were recorded: Frankliniella intonsa (Trybom 1895), Thrips hawaiiensis (Morgan), Thrips tabaci Lindeman Hercinothrips femoralis (Reuter), Pentalonia nigronervosa Coquerel, Rhopalosiphum maidis (Fitch), Brachycaudus helichrysi (Kaltenbach), Tetranychus turkestani Ugarov & Nycolsky, Tetranychus urticae Koch, Spodoptera littoralis (Boisduval), Bemisia tabaci (Gennadius), Aleyrodes sp., Planococcus citri (Risso), Dysmicoccus brevipes (Cockerell), Ceroplastes rusci (L.), Coccus hesperidum L., and Chrysomphalus aonidum (L.). Twenty-two natural enemies from six orders and thirteen families were identified. This study also provides the first Turkish records of parasitoid Coccophagus shillongensis Hayat and Singh from C. hesperidum and Encarsia aurantii (Howard) from C. aonidum. The data showed that spider mites were the most abundant pests, while phytoseiid mites were their most abundant natural enemies. This study represents an important contribution to the scarce literature on insect and mite fauna associated with banana greenhouses in the Western Mediterranean Region. The findings are expected to contribute to the development of effective and sustainable pest management strategies for greenhouse banana production. Full article

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. Full article

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. Full article

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. Full article

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. Full article

Plants are challenged regularly with multiple types of biotic stress factors, such as pathogens or insect herbivores, in their environment. To detect and defend against pathogens, plants have evolved an innate immune system in which intracellular receptors in the so-called effector-triggered immunity play a vital role. In Arabidopsis thaliana the Toll/interleukin-1 receptors (TIRs) domain is related to intracellular immunity receptors, for example in TIR-NBS-LRR (TNL) proteins. Among the TIR domain carrying proteins, very little is known about the function of the TIR-X proteins. Here, we focus on the recently described TIR-X (TIRP; At5g44900) to analyze its role in phytohormone-mediated plant defense through gene expression and phytohormone quantification. Therefore, we employed two fungal pathogens, the necrotrophic Alternaria brassicicola and the hemibiotrophic Verticillium dahliae, to infect A. thaliana WT (Col-0), TIRP knock-out, and TIRP overexpressing lines for comparative analyses. Furthermore, we included the insect herbivore Spodoptera littoralis and a treatment with S. littoralis egg extract on the plants to analyze any role of TIRP during these attacks. We found that both A. brassicicola and V. dahliae infections increased TIRP gene expression systemically. The salicylic acid content was higher in the TIRP overexpressing line, corresponding to a better S. littoralis larval growth performance in feeding assays. However, since we never observed clear infection-related differences in jasmonate or salicylic acid levels between the wild type and the two transgenic Arabidopsis lines, our results rule out the possibility that TIRP acts via the regulation of phytohormone synthesis and accumulation. Full article

Chrysoperla carnea (Stephens) is a common generalist predator in agroecosystems, frequently used for the control of soft-bodied pests in augmentative releases. Better knowledge of its interactions with secondary natural prey is necessary to optimize field biocontrol performance. This work evaluates the eggs and early larvae of Spodoptera exigua (Hübner) and Spodoptera littoralis (Boisduval) as natural prey for the third larval instar of C. carnea, and the predator preferences for different prey stages under varying conditions, assessing the impact on its life cycle and reproduction, in comparison with commercial diets based on Ephestia kuehniella Zeller eggs. Prey choice results were uniform for each dual prey combination irrespective of previous predator conditions (larvae number or fasting). Chrysoperla carnea did not show preference for Ephestia or Spodoptera eggs, but preferred eggs prior to larvae of the natural prey. Diets based on the frozen eggs of natural and factitious prey species showed similar effects on the development and reproduction of predator, but when C. carnea fed on S. exigua larvae, several negative effects were assessed, such as longer preimaginal development, lower adult emergence, and a reduced fecundity. These results are helpful for improving the use of lacewings as biocontrol agents in pest control programs. Full article

Endolichenic fungi represent an important ecological group of microorganisms that form associations with photobionts in the lichen thallus. These endofungi that live in and coevolve with lichens are known for synthesizing secondary metabolites with novel structures and diverse chemical skeletons making them an unexplored microbial community of great interest. As part of our search for new phytoprotectants, in this work, we studied the endolichenic fungus Xylaria sp. isolated from the lichen Hypogymnia tubulosa, which grows as an epiphyte on the bark of the endemic Canarian tree Pinus canariensis. From the extract of the liquid fermentation, we isolated two unreported piliformic derivatives, (+)-9-hydroxypiliformic acid (1) and (+)-8-hydroxypiliformic acid (2), along with four previously reported compounds, (+)-piliformic acid (3), hexylaconitic acid A anhydride (4), 2-hydroxyphenylacetic acid (5), and 4-hydroxyphenylacetic acid (6). Their structures were elucidated based on NMR and HRESIMS data. The extract and the isolated compounds were tested for their insect antifeedant (Myzus persicae, Rhopalosiphum padi, and Spodoptera littoralis), antifungal (Alternaria alternata, Botrytis cinerea, and Fusarium oxysporum), nematicidal (Meloidogyne javanica), and phytotoxic effects on mono- and dicotyledonous plant models (Lolium perenne and Lactuca sativa). Compounds 4, 5, and 6 were effective antifeedants against M. persicae and 4 was also active against R. padi. Moreover, 3 and 4 showed antifungal activity against B. cinerea and 4 was the only nematicidal. The extract had a strong phytotoxic effect on L. sativa and L. perenne growth, with compounds 3, 4, and 5 identified as the phytotoxic agents, while at low concentrations compounds 3 and 4 stimulated L. sativa root growth. Full article

Agricultural pollutants co-interact and affect the vital functions, stress tolerance, resistance, immunity, and survival of insect pests. These metal–herbicide interactions have inevitable but remarkable effects on insects, which remain poorly understood. Here, we examined the effects of the interactions among zinc (Zn), iron (Fe), and paraquat (PQ) at a sublethal dose on the physiological response of the Egyptian cotton leafworm Spodoptera littoralis. Co-exposure to Zn and Fe improved leafworm survival (100% at 10–20 mg, 85% at 40 mg) compared to separate exposures. Low Zn/Fe/PQ toxicity likely stemmed from metal complexes having efficient chelating activity, enhancing resilience. Low exposure to Zn, Fe, and Zn/Fe increased food intake and larval weight and affected frass production. Interestingly, the combined application of Zn/Fe/PQ increased larval and pupal weight in surviving individuals. Zn/Fe was found to be crucial in the ecdysis of larvae into pupae, resulting in reduced larval mortality and a prolonged pupal ecdysis duration (% days). Providing important information regarding physiological responses and pest management, this study demonstrated the realistic conditions caused by the interactions of biological trace elements, such as Zn and Fe, with PQ. A disc diffusion susceptibility test in hemolymph bacteria revealed differences among Zn, Zn/Fe, and Zn/Fe/PQ, suggesting that their interaction might play an immunomodulatory role in S. littoralis. Full article

Trichomes play a key role in both heavy metal tolerance and herbivory defense, and both stressors have been shown to induce increased trichome density. However, the combined effect of these stressors on trichome density in general, and specifically on metal-hyperaccumulating plants, has yet to be examined. The aim of this study was to test the effect of cadmium availability and herbivory on leaf trichome density and herbivore deterrence in the metal hyperaccumulator Helianthus annuus. To test this, H. Annuus plants were grown in control pots or pots inoculated with 10 mg/kg cadmium and were subjected to either no herbivory or simulated herbivory using mechanical damage and foliar jasmonic acid application. Herbivore deterrence was tested in a feeding assay using Spodoptera littoralis caterpillars. Interestingly, while the trichome density of H. annuus increased by 79% or 53.5% under high cadmium availability or simulated herbivory, respectively, it decreased by 26% when the stressors were combined. Furthermore, regardless of cadmium availability, simulated herbivory induced a 40% increase in deterrence of S. littoralis. These findings suggest that the combination of metal availability and herbivory might present excessive stress to hyperaccumulators. Moreover, they suggest that the risk of metal bioaccumulation in phytoremediation can be reduced by simulated herbivory. Full article