Search Results (767)

Background/Objectives: Herbivorous insects feed on plant tissues to obtain nutrients necessary for growth and development while simultaneously ingesting diverse plant secondary metabolites. Understanding the fate of these compounds during digestion is important for advancing knowledge of insect nutritional physiology and diet-associated biochemical processes. This study aimed to comparatively profile metabolites in host plants and corresponding insect gut extracts to generate insights into compound transfer and compositional changes within these systems. Methods: Gas Chromatography-Mass Spectrometry (GC-MS) metabolomics was combined with Ultraviolet-Visible (UV–Vis) quantification of total phenols and flavonoids to compare host plant tissues and insect gut extracts in three systems: fall armyworm (Spodoptera frugiperda) larvae on maize (Zea mays), desert locust (Schistocerca gregaria) on wheatgrass (Triticum aestivum), and silkworm (Bombyx mori) on mulberry (Morus alba). The analytical approach targeted semi-volatile and moderate polar compounds within the constraints of the extraction and detection workflow. Results: UV–Vis analysis revealed consistent enrichment of total phenols in insect guts relative to host plants (1.4- to 0.35-fold), while flavonoids were reduced (2- to 7-fold). GC-MS analyses showed clear separation of gut and plant metabolomes, with <35% shared metabolites and the majority unique to insect guts. Insect extracts were enriched in hydrocarbons, fatty acids, sterols, and terpenoid derivatives, reflecting extensive biochemical transformation. Sex-specific metabolite differences were observed in silkworm and desert locust guts despite identical diets. These findings show differences between plant and gut metabolite profiles, reflecting selective enrichment, depletion, and restructuring of dietary compounds during digestion. Overall, this study provides comparative metabolic data on insect–plant feeding systems and highlights the gut as a dynamic environment associated with changes in dietary metabolite composition. These findings contribute to understanding how plant-derived compounds are represented in insect gut extracts and establish a baseline framework for future studies investigating the biochemical processes underlying insect digestion and nutrient utilization. Full article

Beyond its function as a carrier of hereditary information, recent research has uncovered novel properties of extracellular DNA, including its role in the adaptation to the environment when released from plants. The secreted DNA has been shown to exert insecticidal effects against insect pests, which play an adaptive role in plant-insect interactions, particularly in regulating populations of economically important sap-feeding insects. The molecular mechanisms underlying this insecticidal effect are underinvestigated and remain largely unknown. Therefore, there is a need for more efforts to uncover these mechanisms to better understand plant–pest interactions, which would provide new insights into natural pest control strategies and inspire biotechnological applications. In the current study, we show that Pittosporum tobira (P. tobira) secretes single-stranded DNA (ssDNA) that exerts an insecticidal effect on Coccus hesperidum (C. hesperidum). We collected extracellular DNA from P. tobira leaves and tested its potential insecticidal effect by applying it to C. hesperidum, which is a well-known pest that causes damage to P. tobira. Our results revealed that the outermost layer of the leaf cuticle of P. tobira predominantly contains ssDNA of approximately 100 nt in length, originating from both chloroplast and nuclear genomes. This DNA exhibited pronounced insecticidal activity against C. hesperidum, with chloroplast-derived sequences significantly enriched compared to the total DNA in intact plant cells. These findings suggest that the microevolution of the P. tobira nucleome and plastome contributed to the formation of extracellular DNA with insecticidal properties (eci-DNA), which is part of its defense strategy against insect pests. Moreover, in this article, for the first time, we show that antisense DNA (illustrated with oligonucleotide insecticide Coccus-11) is capable of activating insect retrotransposons and upregulating their RT-RNase H, a crucial enzyme for the DNA containment mechanism and successful action of oligonucleotide insecticides. Notably, the laboratory-developed ssDNA-based ‘genetic zipper’ technology, designed for sustainable pest management, possesses characteristics similar to eci-DNA found in nature, highlighting a potential natural parallel to this biotechnological approach for sustainable pest management. Full article

The study assessed the impact of climate change, aphid infestation and drought stress on winter wheat (Triticum aestivum L.) and the performance of English grain aphid (Sitobion avenae) under abiotic stress in controlled environmental conditions. To understand wheat and aphid interactions under different climatic condition, wheat plants were grown in controlled climatic chambers simulating present (400 ppm CO₂, 19.8 °C, RH 69.2%) and future (700 ppm CO₂, 23.4 °C, RH 67.5%) scenarios, combined with biotic stress (aphid) and abiotic stress (drought). Climate change effects combined with other stress factors are expected to alter crop physiology and insect biology. The results showed that aphid performance was significantly enhanced under future climatic conditions, with higher fecundity (56%), and a shortened or faster developmental time. As for wheat structural growth, above-ground biomass improved by up to 80% under future climate. However, its physiological efficiency, water content and photosynthetic efficiency were significantly reduced under the combined biotic and abiotic stresses. The study demonstrates that climate change may increase wheat plant growth under controlled conditions, yet it simultaneously boosts the shift in pest attacks and intensifies stress impacts, which eventually threaten wheat productivity. The findings emphasize the improvement of wheat varieties and pest-resistant strains capable of withstanding future climatic conditions. Full article

Woody plants in managed and natural ecosystems are increasingly exposed to arthropod pest pressure, posing challenges for sustainable plant protection. This study evaluates trunk injection as a pest management strategy in woody species, with emphasis on plant-mediated processes shaping interactions between host plants and herbivorous arthropods. Two experimental systems were investigated: a greenhouse experiment with Gleditsia triacanthos and a field experiment with Quercus petraea. Systemic active ingredients (acetamiprid and abamectin) were applied using both experimental and professional injection devices, and their effectiveness was assessed against Tetranychus urticae and a complex of foliar-feeding insects. In the greenhouse experiment, trunk injection reduced T. urticae populations compared with untreated controls and soil drench treatments, with reductions of 55.6–58.4% for larvae, 65.7–67.5% for eggs, and 28.7% for adults, although foliar application achieved higher suppression (up to 81.2% for eggs). In the field experiment, treatments reduced leaf discoloration (from 16.3% in control to 1.45–3.80%) and skeletonization (from 15.1% to 9.95–12.7%), with more moderate effects on defoliation. Differences among feeding guilds suggest that responses to systemically distributed compounds depend on feeding behavior and canopy position. Both pressurized and non-pressurized methods enabled uptake and translocation of active compounds within plant tissues. Localized injuries were observed at injection points, including internal necrosis. Overall, trunk injection represents a viable approach for pest management in woody plants, highlighting the role of plant-mediated processes in shaping treatment outcomes under contrasting conditions. Full article

The Clavicipitaceae family, including saprobes and insect and myco-pathogens, are widely distributed in nature across various trophic regions, and play important roles in insect population control, plant interactions, and symbiotic evolution. Members of the genus Moelleriella within this family primarily specialize in infecting scale insects and whiteflies. Using five genomic loci (SSU, LSU, tef1-α, rpb1, and rpb2), we report on the inferred divergence times among members of Clavicipitaceae using molecular dating analyses. Molecular clock estimates revealed that the ancestor of Moelleriella likely emerged in the Late Cretaceous (91.60 Mya; 95% highest posterior density of 79.29–100.13 Mya). Historical biogeographic reconstruction of Moelleriella, performed using the Bayesian Binary Markov chain Monte Carlo (BBM) method, indicates that it most likely originated in Asia. Moreover, based on taxonomic and phylogenetic analyses, we describe three species within the genus Moelleriella, including one new species (Moelleriella microstroma) and two new records for China (Moelleriella chiangmaiensis and Moelleriella phukhiaoensis). Full article

Urbanization reduces biodiversity and affects plant–insect interactions, creating a need for more functional green spaces. Urban meadows with native species are a promising option, but their use is still limited due to a variety of reasons concerning the utilization framework of suitable plant species. The present study aimed to develop seed germination protocols for 26 native Mediterranean herbaceous species originating from northeastern Greece selected to support the establishment of species-rich and self-sustaining urban meadows. To the above end, seed germination experiments were conducted ex situ under controlled environment conditions using seeds collected from the wild for each species. Seed viability was assessed using the tetrazolium (TTZ) test to determine the maximum germination potential in each case. Freshly collected seeds were stored under ambient conditions for approximately 3 months (after-ripening) prior to germination testing, which was followed by cold stratification as a pretreatment for dormancy release. The results showed high embryo viability in all species and indicated that most taxa exhibited either no dormancy or relatively shallow physiological dormancy. Germination tests revealed that 14 of the 26 species presented high germination percentages in the control treatment, which suggests that after-ripening contributed to dormancy release in a significant portion of the seed lot. However, it remains unclear whether freshly collected seeds require an initial after-ripening period before responding to cold stratification. Furthermore, cold stratification significantly enhanced germination in 12 species confirming its effectiveness as a simple and practical method for dormancy release. In addition to the seed germination results, the selected species present a wide range of functional and esthetic characteristics, including variation in plant height, flowering phenology and flower and leaf color. These traits are important for both ecological performance and visual quality in urban environments. The combination of extended flowering periods and color diversity suggests the potential for continuous floral resource availability, which can support diverse pollinator communities and, indirectly, urban fauna such as insectivorous birds. The results indicate that the studied species are suitable for biodiversity-oriented urban plantings. Their relatively shallow dormancy and ease of propagation, coupled with their functional and aesthetic traits, support their use in the development of resilient and self-sustaining urban meadows. Full article

Antimicrobial peptides (AMPs) are natural bioactive peptides produced by all organisms—from plants to insects, microbes and animals—and constitute a first line of defense. As they exhibit a broad spectrum of activity (antibacterial, antiviral, antifungal, antiparasitic, anticancer), strong efforts are being made to integrate AMPs into clinical use. AMPs are also being investigated as anticancer agents to overcome the side effects and/or resistance associated with current chemotherapies. In this context, we identified the natural AMP chionodracine from a new biological source: an Antarctic fish. Starting from the fragmentation of a chionodracine mutant peptide, a rational modular design approach was applied to develop three very short peptides (Pep-A, Pep-B and Pep-C), which were further modified with an N-terminal myristic acid lipid tail. The anticancer activity of the three N-myristoylated short peptides (Myr-A, Myr-B and Myr-C) was explored against the human cervical cancer HeLa cell line. The rationale behind this study is based on the previously reported antifungal activity of these myr peptides and on their ability to interact selectively with biological membrane-mimicking synthetic phospholipids without being particularly hemolytic or cytotoxic towards normal cells. We first demonstrated that myr peptides had cytotoxic activity against HeLa cells (IC₅₀ from 32 to 47 μM) but spared healthy primary human fibroblasts, whereas the corresponding non-myr peptides failed to kill cancer cells. The peptide with no hemolytic activity and a low IC₅₀, labeled Myr-B, was selected for subsequent analyses. Lactate dehydrogenase (LDH) assay and scanning electron microscopy (SEM) analysis revealed membrane damage and predominantly necrotic cell death in HeLa cells exposed to IC₅₀ doses of the Myr-B peptide, compared with cells treated with Pep-B. To thoroughly investigate the molecular effects of Myr-B in HeLa cells, we employed high-resolution label-free shotgun quantitative proteomics coupled with bioinformatics. Our results showed that exposing HeLa cells to Myr-B led to the under-expression of proteins belonging to the “apoptosis- and splicing-associated protein complex”, potentially influencing the alternative splicing process and consequently leading to a possible susceptibility to programmed cell death. These findings indicate that modifying natural AMPs may be a promising strategy for developing selective anticancer drugs and pinpoint Myr-B as an interesting target for future studies. Full article

Butterflies locate host sites using plant volatiles, while larval frass cues induce avoidance. This study investigated the olfactory responses of adult Papilio polytes to nine shared plant and frass volatiles across 1 × 10³ to 1 × 10⁶ ng load doses using electroantennography (EAG) and Y-tube olfactometer assays. EAG responses were significantly influenced by chemical composition, dose, and sex, as well as all their interactions. In contrast, behavioral choices were significantly driven only by chemical composition and its interaction with dose. Although females exhibited higher peripheral sensitivity than males, this physiological sexual dimorphism did not result in significant behavioral differences. Linalool, citronellal, and geraniol were identified as the most potent elicitors. While their single forms and binary blends elicited attraction or neutrality, the ternary mixture significantly repelled both sexes. These results demonstrate that VOC blend composition determines the direction of behavioral responses, with linalool playing a pivotal role in the transition from attraction to avoidance. These findings highlight the importance of shared plant–frass VOCs in host selection by oligophagous insects and provide a foundation for manipulating P. polytes behavior. Full article

A comprehensive annotated checklist of the members of the phytophagous ladybird beetle tribe Epilachnini (Coccinellinae) in China is compiled based on existing published sources and incorporates the latest taxonomic and nomenclatural updates. The checklist documents 176 extant species across 10 genera and provides analyses of regional species richness, distribution, and host plant associations. Regarding regional species richness, Yunnan Province is home to the highest number of species (76), followed by Taiwan (50), Sichuan (48), Guizhou (48), Guangxi (43), Tibet (43), Guangdong (25), Hainan (17), Hubei (17), Hunan (13), Shaanxi (13), Fujian (12), Henan (10), Jiangsu (10), Anhui (7), Shandong (7), Zhejiang (7), Jiangxi (5), Hong Kong (5), Gansu (5), Beijing (4), Hebei (4), Liaoning (3), Shanxi (2), and Chongqing, Jilin, Heilongjiang, Ningxia, and Xinjiang (each with one species). Among the recognized genera, Epilachna Chevrolat, 1837, is currently the most species-rich genera, with 59 species, followed by Afissa Dieke, 1947 (34), Uniparodentata Wang & Cao, 1993 (28), Henosepilachna Li, 1961 (29), Afidentula Kapur, 1958 (10), Diekeana Tomaszewska & Szawaryn, 2015 (9), and Epiverta Dieke, 1947 (4). Additionally, Afidenta Dieke, 1947, Cynegetis Chevrolat, 1837, and Subcoccinella Agassiz & Erichson, 1845 are each represented by a single species. Host plant data are currently available for only 72 species (approximately 41% of the species recorded in China), which are associated with 177 plant species across 34 families. The most frequently recorded host plant families are Solanaceae (43 species), Cucurbitaceae (32), Urticaceae (15), Fabaceae (14), Asteraceae (14), and Poaceae (10), whereas each of the remaining 28 families comprises fewer than 10 host species. For 104 species (59% of the Chinese members of the tribe), host plant associations remain unknown, highlighting a substantial gap in our understanding of their feeding habits. Full article

The obligate mutualism between Ficus and its pollinating wasps provides a suitable system to investigate these dynamics because it encompasses two contrasting pollination modes: active and passive. Here we compared pollen traits in an actively pollinated fig tree, Ficus citrifolia, and a passively pollinated species, F. obtusiuscula, examining pollen both at anther presentation and after deposition on the bodies of their pollinating wasps. Pollen morphology, hydration-related behavior, cytology, and reserve composition were characterized using scanning electron microscopy (conventional and modified), light and transmission electron microscopy, histochemical assays, and viability tests. Across species, pollen traits at anthesis showed broad overlap in morphology, viability and major reserve classes, indicating that these characteristics are not consistently predicted by pollination mode alone. In both species, pollen was bicellular, harmomegathic and highly viable at presentation, consistent with resilience during transport. The main divergence emerged after pollen transfer to the pollinator. In the actively pollinated species, pollen recovered from wasp thoracic pockets exhibited pronounced intracellular remodeling, including vacuolization, starch depletion, lipid redistribution and localized cytoplasmic degradation. By contrast, pollen of the passively pollinated species retained a comparatively stable cytological organization after transport despite changes in reserve distribution. These results suggest that the more pronounced cytoplasmic reorganization observed in the pollen of the actively pollinated species after deposition on the wasp body may represent a preparatory phase for rapid germination following pollination, reflecting the stronger dependence of larval development on successful flower fertilization in actively pollinated figs. More broadly, our study provides the first comparative account of pollen structural and cytophysiological dynamics on fig-wasp bodies, linking pollen cell biology to pollinator-mediated dispersal and highlighting how different pollination strategies may impose distinct selective pressures on male gametophytes. Full article

Endosymbiotic bacteria in insects are known to influence plant–insect interactions by altering host plant physiology. This study reveals that the endosymbiont Wolbachia significantly impairs photosynthesis in cotton plants. Comparative transcriptomic analysis of cotton leaves infested by Wolbachia-infected spider mites (Tt-I) and uninfected spider mites (Tt-UI) identified 1912 differentially expressed genes (DEGs). Photosynthesis was the most adversely affected biological process, with 17 genes downregulated in the photosynthesis pathway (e.g., key genes psbW and PETF), as supported by GO and KEGG enrichment analyses. Gene co-expression network analysis further highlighted core genes involved in photosynthesis disruption and carbon fixation. Physiological assessments showed that Wolbachia infection led to significantly reduced chlorophyll content and elevated reactive oxygen species (ROS) levels, inducing oxidative stress. These findings demonstrate that Wolbachia disrupts cotton photosynthesis through transcriptional repression and ROS-mediated oxidative stress, providing novel insights into plant–insect-symbiont interactions and a theoretical basis for managing mite pests in cotton. Full article

Plant volatiles are critical mediators of insect–plant interactions, guiding natural enemies to specific habitats and prey. The flower bug, Orius maxidentex Ghauri (Hemiptera: Anthocoridae), is a generalist predator that exhibits a specialized ecological association with the weed Celosia argentea L. (Caryophyllales: Amaranthaceae), utilizing the plant as a primary floral niche in Hainan Island. In this study, the attractiveness of C. argentea floral volatiles to O. maxidentex was confirmed using a Y-tube olfactometer. Solid-phase microextraction (SPME) combined with gas chromatography–mass spectrometry (GC-MS) was utilized to identify six compounds in the floral volatiles: 1,3-diethenylbenzene, trans-cinnamaldehyde, β-bisabolene, methyl salicylate, 3-ethylbenzaldehyde, and nonanal. Electroantennogram (EAG) assays revealed that O. maxidentex antennae showed significant physiological responses to these compounds, and the EAG relative values were positively correlated with concentration gradients. Furthermore, O. maxidentex exhibited significant orientation responses to 1,3-diethenylbenzene, trans-cinnamaldehyde, β-bisabolene, and methyl salicylate, whereas no behavioral response was observed for 3-ethylbenzaldehyde or nonanal. Further tests revealed that β-bisabolene elicited the highest attractiveness, comparable to a synthetic blend formulated to mimic the natural release ratio of the active semiochemicals. These findings reveal the hidden chemical cues mediating the interaction between a predator and its preferred habitat. Understanding this mechanism not only helps explain insect adaptation but also offers new strategies for using these plant volatiles to influence the behavior of this specific predator, potentially enhancing its targeted recruitment in agroecosystems. Full article

The damage caused by herbivores is generally measured as the amount of leaf tissue consumed, without accounting for the fate of the leftover tissue. As a result, the plant defense mechanisms that promote resistance to herbivore feeding by photosynthetically acclimating the rest of the plant to the feeding spot leaf area have not been well exploited. Plant-insect interactions are now becoming better defined with the development of visualization methods that permit spatial whole-leaf assessment of photosynthetic efficiency after herbivore attack. The purpose of our study was to evaluate the spatial heterogeneity of photosystem II (PSII) function at the whole-leaf level before and after herbivory by the Colorado potato beetles. Twenty minutes after Colorado potato beetle (Leptinotarsa decemlineata) feeding, the maximum efficiency of PSII photochemistry (Fv/Fm) decreased significantly, suggesting photoinhibition due to reduced efficiency of the oxygen-evolving complex (OEC). The decreased quantum yield of PSII photochemistry (Φ_PSII) after feeding, at the neighboring area of the feeding spot and at the rest of the leaf area, was attributed to the reduced efficiency of the open PSII reaction centers (Fv′/Fm′), since there was no change in the fraction of open PSII reaction centers (qp). Nevertheless, plant defense elicitation was activated by the photoprotective mechanism of non-photochemical quenching (NPQ) that reduced the singlet oxygen (¹O₂) formation in potato plants in the neighboring area of the feeding spot and at the rest of the leaf area. In addition, the increased production of hydrogen peroxide (H₂O₂) triggered by this increase suggests that it acted as a signaling molecule in the biotic stress defense response. Full article

Three-dimensional (3D) epicuticular wax coverage on plant surfaces contributes to multifunctional surface properties, such as enhanced water repellence, reduced pathogen adherence, modified optical properties, and reduced insect adhesion. The diversity in wax projection morphology, size, abundance, and spatial arrangement among plant species results in a broad spectrum of anti-adhesive effects, reflecting both phylogenetic history and ecological function. This study presents a numerical model consisting of 3D tubular-shaped structures randomly deposited on a substrate and forming a highly porous layer. The simulations based on this model demonstrate a strong reduction in adhesion to the contacting insect adhesive pad. It is found that a structure formed by sufficiently long tubes, where the length is enough to support the tubes in space and build a porous 3D structure with a very low density, at relatively weak attraction to the underlying substrate, leads to the weakest adhesion. The model is constructed on the basis of our recent works combining discrete and continuous approaches in biological modeling. It mainly exploits the technique of the movable digital automata, allowing modeling of numerous numerically elastic cylinders that can be moved in 3D space, elastically collide with one another and with boundaries, and build self-consistent surface structures, which can be used to mimic nano- or microscale surface coverages of real plants. Full article

In this study, we propose a compartmental mathematical model that considers two interacting populations (citrus plants and insect vectors) and investigate the transmission dynamics of Huanglongbing in citrus crops. This disease is caused by the bacterium Candidatus Liberibacter asiaticus and is vectored by the psyllid Diaphorina citri. The disease is modeled under the following three main assumptions: there is vital dynamics with constant recruitment rates of citrus plants, the force of infection in both populations is a spatially dependent function varying with geographic location, and there is a spatial displacement of the vectors. In the main results of the paper, we formulate a coupled ordinary and partial differential equation system with initial and zero flux boundary conditions, establish the existence and uniqueness of solutions to the proposed model by applying semigroup theory, and introduce a numerical approximation of the system. Moreover, we develop a stability and persistence analysis. From the analytical point of view, we calculate the basic reproduction number $R_0$ and prove three facts: the disease-free equilibrium is globally asymptotically stable when $R_0<1$; the disease-free equilibrium is globally asymptotically stable when $R_0>1$; and the hybrid system exhibits uniform persistence of infection when $R_0>1$. In addition, we present some numerical examples. Full article