Search Results (382)

Bilberry (Vaccinium myrtillus L.) expansion in subalpine and alpine ecosystems is increasing due to climate change and reduced land management. This review examines bilberry traits, environmental responses, and ecosystem impacts. As a stress-tolerant chamaephyte, bilberry thrives in acidic, nutrient-poor soils across various habitats. It propagates effectively through rhizomes and demonstrates a phalanx growth form. Bilberry’s growth and distribution are influenced by elevation, soil structure, pH, water availability, and nitrogen content. Mycorrhizal associations play a crucial role in nutrient uptake. The species modifies the microclimate, facilitates litter accumulation, and influences soil microbial communities, affecting nutrient turnover and biodiversity. Bilberry shows moderate tolerance to herbivory and frost, with the ability to recover through rapid emergence of new ramets. However, severe or repeated disturbances can significantly impact its abundance and reproductive success. Climate warming and atmospheric nitrogen deposition have accelerated bilberry growth in treeline ecotones. The management of bilberry expansion requires a nuanced approach, considering its resilience, historical land-use changes, and environmental factors. The goal should be to limit, not eliminate, bilberry, as it is a natural part of subalpine communities. Long-term comparative monitoring and experimental manipulation are necessary for effective management strategies. Full article

Fall armyworm (FAW, Spodoptera frugiperda) has now spread to more than 26 Chinese provinces. The government is working with farmers and researchers to find ways to prevent and control this pest. The use of biochar is one of the economic and environmentally friendly strategies to increase plant growth and improve pest resistance. We tested four v/v combinations of bamboo charcoal with coconut bran [BC1 (10:1), BC2(30:1), BC3(50:1)] against a control (CK) in maize. We found that plant height, stem thickness, fresh weight and chlorophyll content were significantly higher in BC2, in addition to the lowest FAW survival %. We then compared the metabolome and transcriptome profiles of BC2 and CK maize plants under FAW herbivory. Our results show that the levels of flavonoids, amino acids and derivatives, nucleotides and derivatives and most phenolic acids decreased, while terpenoids, organic acids, lipids and defense-related hormones increased in BC-grown maize leaves. Transcriptome sequencing revealed consistent expression profiles of genes enriched in these pathways. We also observed the increased expression of genes related to abscisic acid, jasmonic acid, auxin and MAPK signaling. Based on these observations, we discussed the possible pathways involved in maize against FAW herbivory. We conclude that bamboo charcoal induces anti-herbivory responses in maize leaves. Full article

The spatial extent of semi-arid hot regions is forecasted to grow through the twenty-first century, complicating restoration and reforestation plans. In arid and semi-arid climates, seedlings are more susceptible to transplant shock due to lower soil moisture throughout the year. Determining strategies to reduce seedling stress and improve survival post-planting will be paramount to continued reforestation efforts in a changing climate. We quantified seedling physiological, morphological, and field performance (mortality and growth) response for five species native to the semi-arid region of South Texas (Erythrina herbacea L., Celtis pallida Torr., Fraxinus berlandieriana DC, Malpighia glabra L., and Citharexylum berlandieri B.L Rob) to an antitranspirant (abscisic acid), drought, and elevated CO₂. We examined post-treatment seedling gas exchange, non-structural carbohydrates, osmolality, root structure, and stomatal density and evaluated mortality and growth rate on a sample of the treatment population. For elevated CO₂ and drought hardening treatments, seedling gas exchange, solute content, specific root length, and stomatal density varied by species, while abscisic acid strongly reduced transpiration and stomatal conductance in all species. However, these physiological and morphological differences did not translate to reduced mortality or improved growth rate due to high herbivory and above-normal precipitation after planting precluding seedlings from stress. We conclude that the simpler antitranspirant approach, rather than the more logistically challenging eCO₂, has the potential to reduce drought-related transplant shock but requires more widespread testing. Full article

Wild herbivore responses to anthropogenic climate change are often projected to be habitat and geographic range shifts as warmer conditions reduce the quantity and nutritional quality of forage plants, which makes species presence/absence a focus. Since 1978, herbivore abundances at the National Bison Range, MT, USA, were measured for grasshoppers (catch-effort), microtine rodents (runway density), and ungulates (drives and round-ups), along with climate and vegetation quantity (biomass) and quality (nitrogen content and chemical solubility related to digestibility). Counter to expectation with warming and drying, forage biomass increased as grass biomass increased more than dicot biomass decreased, and forage quality (solubility) increased. Consequently, herbivores that consume a grass diet (>25% grass: certain grasshoppers, microtines, bighorn sheep, elk, bison) increased in abundance, while herbivores consuming less grass declined (certain grasshoppers, pronghorn, whitetail, and mule deer). The result is an 18% increase in herbivore abundance and herbivory, counter to climate change expectations. Historically, grasshoppers consumed 46% more vegetation than mammals; now, they consume only 14% more, as grasshoppers did not increase as expected with climate change. Therefore, herbivores respond rapidly to climate-induced vegetation changes, and this is not a simple loss/addition of species, but changing trophic dynamics, which requires more knowledge of ecosystem dynamics. Full article

Timber trees are targets of herbivorous attacks. The identification of genes associated with pest resistance can be accomplished through differential expression analysis using transcriptomes. We reported the de novo assembly of cedar (Cedrela odorata L.) transcriptome and the differential expression of genes involved in herbivore resistance. The assembly and annotation of the transcriptome were obtained using RNAseq from healthy cedar plants and those infested with Chrysobothris yucatanensis. A total of 325.6 million reads were obtained, and 127,031 (97.47%) sequences were successfully assembled. A total of 220 herbivory-related genes were detected, of which 170 genes were annotated using GO terms, and 161 genes with 245 functions were identified—165, 75, and 5 were molecular functions, biological processes, and cellular components, respectively. To protect against herbivorous infestation, trees produce toxins and volatile compounds which are modulated by signaling pathways and gene expression related to molecular functions and biological processes. The limited number of genes identified as cellular components suggests that there are minimal alterations in cellular structure in response to borer attack. The chitin recognition protein, jasmonate ZIM-domain (JAZ) motifs, and response regulator receiver domain were found to be overexpressed, whereas the terpene synthase, cytochrome P450, and protein kinase domain gene families were underexpressed. This is the first report of a cedar transcriptome focusing on genes that are overexpressed in healthy plants and underexpressed in infested plants. This method may be a viable option for identifying genes associated with herbivore resistance. Full article

Plant herbivore interactions have long been recognized as a complex interplay influenced by various factors, including plant volatile emissions. Understanding the role of these volatiles in mediating plant predator interactions is crucial for developing sustainable pest management strategies. This study investigated the olfactory preferences of Chrysoperla externa larvae for volatiles emitted by Eucalyptus urograndis leaves, focusing on both seedlings and essential oils (EOs). We used Y-tube olfactometry to compare larval preferences between the clean air and various plant treatments, including undamaged and herbivore-damaged leaves. Chemical analysis of EOs revealed higher concentrations of oxygenated monoterpenes and sesquiterpenes in young and damaged leaves, particularly linalool, which has been implicated in insect attraction. Our results showed a significant preference for volatiles emitted by young damaged leaves over clean air for both seedlings (χ² = 11.03, p = 0.001) and EOs (χ² = 9.76, p = 0.002). Chrysoperla externa larvae are significantly attracted to specific volatiles from damaged E. urograndis leaves, suggesting these compounds could serve as cues for natural enemy foraging. Our findings enhance the understanding of plant–predator dynamics and suggest potential applications of eucalyptus plantations to sustain C. externa populations for biocontrol purposes. Full article

Increasing temperatures, prolonged drought, the increased severity and intensity of storms, and other effects of climate change are being felt globally, and long-lived forest tree species may struggle in their current ranges. Oaks (Quercus spp.) have evolved a range of adaptations to dry and hot conditions and are believed to be a “climate change winner” by increasing their suitable habitat. However, a mixture of life history traits and increasing susceptibility to herbivores and xylovores as well as secondary pathogen infections still put oaks at risk of decline. Oak species found in the Midwestern, Great Lakes, and Northeastern United States and Canada are important keystone species with high ecological and economical importance. They are also vulnerable to existing, new, and emerging threats that have the potential to cause mortality across entire stands quickly. Current examples of insect threats include the Lymantria dispar (spongy moth), Agrilus bilineatus (twolined chestnut borer), and Nitidulidae (sap beetles) as disease vectors. Examples of emerging insects of concern include Cynipidae (oak gall wasps) and Enaphalodes rufulus (red oak borer). This study describes these insects, explains their mechanisms of action and the effects on oaks, and explores mitigation strategies for each. Full article

Silicon plays a crucial role in enhancing plant tolerance to various abiotic and biotic stresses, including drought, salinity, heavy metals, and pathogen/pest attacks. Its application has shown promising results in improving stress tolerance and productivity in medicinal plants. This review synthesizes findings from numerous studies investigating the mechanisms by which silicon confers stress tolerance, including the regulation of antioxidant systems, water relations, nutrient homeostasis, phytohormone signaling, and stress-responsive gene expression. Additionally, it examines the effects of silicon supplementation on the production of valuable secondary metabolites and essential oils in medicinal plants. Silicon application can significantly mitigate stress-induced damage in plants, including medicinally important species such as borage, honeysuckle, licorice, Damask rose, savory, basil, and eucalyptus. The deposition of silicon in cell walls provides physical reinforcement and acts as a barrier against pathogen invasion and insect herbivory. Furthermore, silicon fertilization can enhance the production of valuable secondary metabolites in medicinal crops under stress conditions. The findings underscore the potential of silicon fertilization as a sustainable strategy for improving the productivity and quality of medicinal crops under changing environmental conditions, highlighting the need for further research to elucidate the molecular mechanisms underlying silicon-mediated stress tolerance and practical applications in medicinal plant cultivation. Full article

Headwater streams are reliant on riparian tree leaf litterfall to fuel brown food webs. Terrestrial agents like herbivores and contaminants can alter plant growth, litter production, litter quality, and the timing of litterfall into streams, influencing aspects of the brown food web. At Mount St. Helens (USA), early successional streams are developing willow (Salix sitchensis) riparian zones. The willows are attacked by stem-boring herbivores, altering litter quality and the timing of litterfall. Within a established experimental plots, willows (male and female plants) were protected from herbivores using insecticides and provided with experimental additions of nitrogen. This enabled us to test the interacting influences of herbivores, nitrogen deposition, and willow sex on leaf litter quality, aquatic litter decomposition, and microbial and invertebrate detritivores. We found weak litter quality effects (higher N and lower C:N) for the herbivore treatment, but no effect of nitrogen deposition. Although litter decomposition rates were not strongly affected by litter treatments, detritivore communities were altered by all treatments. Nitrogen deposition resulted in decreased bacterial richness and decreased fungal diversity in-stream. Aquatic macroinvertebrate communities were influenced by the interacting effects of herbivory and nitrogen addition, with abundances highest in herbivore litter with the greatest N addition. Shredders showed the highest abundance in male, herbivore-attacked litter. The establishment of riparian willows along early successional streams and their interacting effects with herbivores and nitrogen deposition may be influencing detritivore community assembly at Mount St. Helens. More broadly, global changes like increased wet and dry N deposition and expanded ranges of key herbivores might influence tree litter decomposition in many ecosystems. Full article

In the United States, rangelands comprise 30% of the total land cover and serve as a valuable resource for livestock, wildlife, water, and recreation. Rangelands vary in climate and are often subject to disturbances like drought and wildfire. Historic wildfire trends have indicated an increase in wildfire size and frequency, raising societal and ecological concerns about the management of these lands, both pre- and post-wildfire. While there has been investigation into the effects of grazing prior to a wildfire on fire severity and plant mortality, there is limited research related to grazing post-wildfire even though current management paradigms suggest deferring grazing rangeland for two years after a wildfire to avoid additional stress on native plant species. Based on the diversity found across rangeland ecotypes and history with wildfire, the two-year deferment recommendation may need to be reconsidered for some ecosystems. Species found in perennial bunchgrass rangelands like Pseudoroegneria spicata (bluebunch wheatgrass) and Festuca idahoensis (Idaho fescue) may be less susceptible to post-fire grazing than initially thought, necessitating the need for research into different rangeland ecosystems. Full article

Quaking aspen (Populus tremuloides Michx.) landscapes are valued for their biodiversity, water retention, fire mitigation, aesthetics, and recreation opportunities. Across North America, some aspen populations are experiencing population declines as they face uninhibited ungulate browsing, drought, fire suppression, insects, disease, and inappropriate management. Increased human development and recreational use within aspen landscapes can serve as additive stressors, though there is a dearth of literature examining these elements. At a popular recreational area in Utah, USA, identifying the cause of apparent decline within a larger aspen community is complicated by development upstream and recreation-related activities. We sought to (1) assess the overall condition of the aspen at the site, (2) understand key variables that influence aspen conditions, and (3) elucidate how aspen fitness varies across the site. We collected data from forty-five plots using established aspen sampling methods, including ungulate presence, tree characteristics, soil chemistry, and environmental descriptors. Results suggest that a combination of higher levels of browsing and elevated soil sodium may be causing premature mortality and limiting aspen recruitment in a portion of the study area. These findings will inform future management at this site, as well as similar recreational forest settings experiencing compound stressors. Full article

Lipoxygenase (LOX) is associated with responses to plant hormones, environmental stresses, and signaling substances. Methyl jasmonate (MeJA) treatment triggers the production of LOX, polyphenol oxidase, and protease inhibitors in various plants, producing resistance to herbivory. To examine the response of MtLOX24 to MeJA, the phenotypic and physiological changes in Medicago truncatula MtLOX24 overexpression and lox mutant plants were investigated. Additionally, wild-type R108, the MtLOX24-overexpressing line L4, and the mutant lox-1 were utilized as experimental materials to characterize the differentially expressed genes (DEGs) and metabolic pathways in response to MeJA. The results indicate that after treatment with 200 µM of MeJA, the damage in the mutants lox-1 and lox-2 was more serious than in the overexpressing lines L4 and L6, with more significant leaf wilting, yellowing, and oxidative damage in lox-1 and lox-2. Exogenous application of MeJA induced H₂O₂ production and POD activity but reduced CAT activity in the lox mutants. Transcriptome analysis revealed 10,238 DEGs in six libraries of normal-growing groups (cR108, cL4, and clox1) and MeJA-treated groups (R108, L4, and lox1). GO and KEGG functional enrichment analysis demonstrated that under normal growth conditions, the DEGs between the cL4 vs. cR108 and the clox-1 vs. cR108 groups were primarily enriched in signaling pathways such as plant–pathogen interactions, flavonoid biosynthesis, plant hormone signal transduction, the MAPK signaling pathway, and glutathione metabolism. The DEGs of the R108 vs. cR108 and L4 vs. cL4 groups after MeJA treatment were mainly enriched in glutathione metabolism, phenylpropanoid biosynthesis, the MAPK signaling pathway, circadian rhythm, and α-linolenic acid metabolism. Among them, under normal growth conditions, genes like PTI5, PR1, HSPs, PALs, CAD, CCoAOMT, and CYPs showed significant differences between L4 and the wild type, suggesting that the expression of these genes is impacted by MtLOX24 overexpression. CDPKs, CaMCMLs, IFS, JAZ, and other genes were also significantly different between L4 and the wild type upon MeJA treatment, suggesting that they might be important genes involved in JA signaling. This study provides a reference for the study of the response mechanism of MtLOX24 under MeJA signaling. Full article

The cross-hybridization of American chestnut (Castanea dentata (Marsh.) Borkh.) with Chinese chestnut (Castanea mollissima Bl.) is a promising strategy for restoring a blight-resistant strain of this keystone species to the Appalachian mountains. To assess the ecological impacts of hybridization on invertebrate communities, we conducted a study across chestnut plots with varying degrees of hybridization (75%, 94%, or 100% American chestnut). Our findings indicate American chestnut hybridization impacted invertebrate communities above- and belowground. Aboveground insect community composition, insect herbivory, gall infestation, and belowground invertebrate diversity were all altered. While some of these differences could be explained by different growth habits or environmental differences, stark differences in Asian chestnut gall wasp infestation (Dryocosmus kuriphilus Yasumatsu.) suggest a genetic component. These results suggest that chestnut hybridization, and particularly expanded restoration efforts using chestnut hybrids, could impact invertebrate communities above- and belowground in addition to pest dynamics. Understanding these effects is crucial for successful chestnut restoration and ecosystem management. Full article

Claviceptaceous endophytic fungi in the genus Epichloë mostly form a symbiotic relationship with cool-season grasses. Epichloë spp. are capable of producing bioactive alkaloids such as peramines, lolines, ergot alkaloids, and indole-diterpenes, which protect the host plant from herbivory by animals, insects, and nematodes. The host also benefits from enhanced tolerance to abiotic stresses, such as salt, drought, waterlogging, cold, heavy metals, and low nitrogen stress. The bioactive alkaloids produced can have both direct and indirect effects towards plant parasitic nematodes. Direct interaction with nematodes’ motile stages can cause paralysis (nematostatic effect) or death (nematicidal effect). Indirectly, the metabolites may induce host immunity which inhibits feeding and subsequent nematode development. This review highlights the different mechanisms through which this interaction and the metabolites produced have been explored in the suppression of plant parasitic nematodes and also how the specific interactions between different grass genotypes and endophyte strains result in variable suppression of different nematode species. An understanding of the different grass–endophyte interactions and their successes and failures in suppressing various nematode species is essential to enable the proper selection of grass–endophyte combinations to identify the alkaloids produced, concentrations required, and determine which nematodes are sensitive to which specific alkaloids. Full article

Hymenoptera is the fourth-most diverse insect order today, including wasps, bees, bumblebees, and ants. They show a wide panoply of modes of life, such as herbivory, predation, parasitoidism, pollination, and eusociality. This group also includes a great number of extinct species from both amber and compression outcrops. Hymenopterans probably originated in the Paleozoic, although their oldest record is from the Middle or Late Triassic, and their diversity expanded since the Cretaceous. Here, we present a review of the Hymenoptera in Lower Cretaceous ambers from Lebanon (Barremian) and Spain (Albian), which is pivotal for the study of hymenopteran evolution. Hymenoptera in Lebanese ambers are represented by 32 species in 22 genera within 15 families, while in Spanish ambers, they correspond to 49 species in 40 genera within 18 families. Most of these species belong to the ‘Parasitica’, and only a few species have been assigned to the Aculeata. The group ‘Symphyta’ is represented by one species in Spanish amber. The paleobiogeography and possible paleobiologies of the species in these ambers are reviewed. Furthermore, checklists for all Hymenoptera species in Lebanese and Spanish ambers are provided. Full article