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True sawflies (Tenthredinoidea) have a substantial fossil record but are rarely encountered in Eocene ambers. Here we describe three new taxa in this superfamily from late Eocene ambers. †Rovnotaxonus aristovi gen. et sp. nov. is the first true sawfly reported from Rovno amber. Based primarily on characters in the fore wing venation, we assign the new taxon to Tenthredinidae: Allantinae: Allantini. We also describe two new species of Diprionidae from Baltic amber: †Eodiprion pectinatus sp. nov. from a female specimen and †Monodiprion gladius gen. et sp. nov. from a male previously reported as †Eodiprion sp. by Schedl (2008); we redescribe †Eodiprion Schedl, 2007 and provide emended diagnoses of the genus and of †Eodiprion groehni Schedl, 2007. We integrate all these fossils as well as †Sambia Vilhelmsen and Engel, 2012 (Tenthredinidae: Tenthredininae) previously described from Baltic amber in a combined data set assembled from previously published morphological and molecular data sets. We analyse the combined data set in a Bayesian framework and implement RoguePlots to evaluate the positions of the fossils. The diprionid fossils are unequivocally placed inside Diprionidae, in a polytomy with extant members of Diprioninae; the Monocteninae, the other subfamily currently recognized in the family, is not retrieved as monophyletic. †Rovnotaxonus is placed inside Allantinae and shares some characters with Taxonus. †Sambia is placed near the base of Tenthredininae. The evaluation of the phylogenetic position of the fossils treated here will make them available for future dating analyses of Tenthredinoidea, helping to further elucidate the evolutionary history of this significant lineage of herbivorous insects. Possible reasons for the comparatively low abundance of true sawflies in late Eocene ambers are discussed. . [ABSTRACT FROM AUTHOR]

Insect herbivory on fossil angiosperm leaves was recorded from the upper Lower Cretaceous Zhonggou Formation in the Hanxia Section of the Jiuquan Basin, Gansu Province, NW China. Four functional feeding groups, including hole feeding, margin feeding, skeletonisation, and galling were recognised on nine fossil angiosperm leaves belonging to three species of eudicot. Ten insect damage types (DTs), including DT01, DT02, DT03, DT12, DT14, DT15, DT26, DT32, DT34, and DT61, were identified based on the insect damage morphotypes. Combined with the fossil records of insects reported from the Lower Cretaceous Zhonggou Formation of Jiuquan Basin, these suggest that there were various herbivorous insects that are related to the insect DTs, such as Blattoidea, Hemiptera, Diptera, Orthoptera, and Coleopterathe, which can related to the insects DTs, and indicate a diversified herbivorous insectangiosperm community in Jiuquan Basin during the late Early Cretaceous. Moreover, the diversified terrestrial ecosystem and fluctuating wet and dry climate in Jiuquan Basin during the late Early Cretaceous, would provide a suitable condition for the radiation of herbaceous angiosperms in Jiuquan Basin during the Aptian–Albian gap and promoting the coevolution of early angiosperms and their related herbivores. [ABSTRACT FROM AUTHOR]

Agricultural ecosystem formation and evolution depend on interactions and communication between multiple organisms. Within this context, communication occurs between microbes, plants, and insects, often involving the release and perception of a wide range of chemical cues. Unraveling how this information is coded and interpreted is critical to expanding our understanding of how agricultural ecosystems function in terms of competition and cooperation. Investigations examining dual interactions (e.g. plant–microbe, insect–microbe, and insect–plant) have resolved some basic components of this communication. However, there is a need for systematically examining multitrophic interactions that occur simultaneously between microorganisms, insects, and plants. A more thorough understanding of these multitrophic interactions has been made possible by recent advancements in the study of such ecological interactions, which are based on a variety of contemporary technologies such as artificial intelligence sensors, multi‐omics, metabarcoding, and others. Frequently, these developments have led to the discovery of startling examples of each member manipulating the other. Here, we review recent advances in the understanding of bottom‐up chemical communication between microorganisms, plants, and insects, and their consequences. We discuss the components of these “chemo‐languages” and how they modify outcomes of multi‐species interactions across trophic levels. Further, we suggest prospects for translating the current basic understanding of multitrophic interactions into strategies that could be applied in agricultural ecosystems to increase food safety and security. [ABSTRACT FROM AUTHOR]

The proportion of leaves of downy birch (Betula pubescens Ehrh.) damaged by insects at ten sites of coniferous forest along the pollution gradient of the Middle Ural copper smelter was analyzed. The study was conducted during periods of moderate (2009) and low (2019) emissions in early and late summer. The proportion of damaged leaves was higher in 2019 and increased towards the end of the growing season but was not associated with distance to the smelter and lead concentration in leaves. [ABSTRACT FROM AUTHOR]

The structure of the community of insect herbivores in a plant can be determined by plant traits and also by interactions with consumers. We studied the herbivores associated with the tropical plant Andira nitida (Fabaceae), aiming to understand the temporal co-occurrence of herbivore insects from different guilds. We monitored and quantified the temporal sequence of appearance and leaf consumption of three herbivore guilds (leaf miners, gall-formers and chewers) at weekly intervals for 23 weeks (between September 2021 and March 2022), testing whether functional leaf traits (leaf area, leaf dry matter content, specific leaf area and leaf age) influence herbivory incidence and intensity. Leaves of A. nitida showed simultaneous damage by miners, chewers and six gall species. We found a temporal sequence in the establishment of leaf herbivores and a preference for young leaves. However, null model analysis indicated independent patterns of association between herbivores, and there was no evidence of co-occurrence or repulsion between herbivores or herbivore guilds. We found that leaf age is a determinant functional trait for the occurrence of all guilds and types of herbivores in A. nitida. However most of the physical characteristics of the leaf did not show a clear effect on the herbivore community. We showed that interactions among herbivores partially explained the organization of herbivorous insects in A. nitida and that patterns of occurrence depend more on the life history of herbivores than on aspects associated with plant functional traits. We suggest that there is differential leaf use by herbivores in time, which leads to the formation of different pairs of co-occurring herbivores. [ABSTRACT FROM AUTHOR]

IInsect pathologists’ attention to the potential of entomopathogenic fungi (EPF) as inducers of plant resistance has increased in recent years. Several types of EPF that have received attention as biocontrol agents for insect pest populations include Beauveria bassiana, Metarhizium anisopliae and Trichoderma sp. because they are able to infect and kill insects directly, has a wide host range, and has been used to control various types of insect pests. Apart from being able to infect and kill insect pests, EPF can also live endophytically in plant tissue and increase plant resistance to pest attacks. The presence of EPF as endophytes is able to induce plant resistance by stimulating an increase phytohormones production. In this article, we reviewed the role of fungi as entomopathogens, the characteristics of entomopathogenic fungi, and their role as inducers of plant resistance. The review was carried out by collecting information from original articles and related reports which reviewed the results of research on the role of entomopathogenic fungi as plant resistance inducers by including the keywords entomopathogenic endophytic fungi, resistance induction, characterization, systemic resistance and herbivorous insects. This systematic review concludes that EPF as an inducer of plant resistance is a very promising control alternative in the development of plant protection management against insect pests. [ABSTRACT FROM AUTHOR]

IInsect pathologists' attention to the potential of entomopathogenic fungi (EPF) as inducers of plant resistance has increased in recent years. Several types of EPF that have received attention as biocontrol agents for insect pest populations include Beauveria bassiana, Metarhizium anisopliae and Trichoderma sp. because they are able to infect and kill insects directly, has a wide host range, and has been used to control various types of insect pests. Apart from being able to infect and kill insect pests, EPF can also live endophytically in plant tissue and increase plant resistance to pest attacks. The presence of EPF as endophytes is able to induce plant resistance by stimulating an increase phytohormones production. In this article, we reviewed the role of fungi as entomopathogens, the characteristics of entomopathogenic fungi, and their role as inducers of plant resistance. The review was carried out by collecting information from original articles and related reports which reviewed the results of research on the role of entomopathogenic fungi as plant resistance inducers by including the keywords entomopathogenic endophytic fungi, resistance induction, characterization, systemic resistance and herbivorous insects. This systematic review concludes that EPF as an inducer of plant resistance is a very promising control alternative in the development of plant protection management against insect pests.

The intricate relationship between herbivorous insects and plants has evolved over millions of years, central to this dynamic interaction are salivary proteins (SPs), which mediate key processes ranging from nutrient acquisition to plant defense manipulation. SPs, sourced from salivary glands, intestinal regurgitation or acquired through horizontal gene transfer, exhibit remarkable functional versatility, influencing insect development, behavior, and adhesion mechanisms. Moreover, SPs play pivotal roles in modulating plant defenses, to induce or inhibit plant defenses as elicitors or effectors. In this review, we delve into the multifaceted roles of SPs in herbivorous insects, highlighting their diverse impacts on insect physiology and plant responses. Through a comprehensive exploration of SP functions, this review aims to deepen our understanding of plant-insect interactions and foster advancements in both fundamental research and practical applications in plant-insect interactions.

Abstract Seasonality is one of the main characteristics of a tropical dry forest that affects the structure of ecological communities. In this context, we evaluated the seasonal diversity of ferns and insects in the tropical dry forest of Morelos, Mexico, to determine whether a relationship exists between the presence of each of these two groups. Hill’s numbers indicated differences in the diversity of both groups according to season. In the rainy season, we recorded the highest diversity of ferns, with 6,471 individuals. In contrast, in the dry season, we recorded only 293 individuals. Regarding the insects, we collected 723 individuals in the rainy season and 171 individuals in the dry season. The order Orthoptera was the most abundant (50%). The best-represented functional group according to feeding guild was that of chewing herbivores. Correlation analysis revealed a positive relationship between insect and fern abundances since, for both groups, the minimum abundance was presented in the dry season and the maximum abundance in the rainy season. We recorded 12 orders of insects associated with eight ferns in the rainy season. Seasonal studies that consider different biological groups are necessary to understand how changes in resource availability shape temporal patterns of species diversity.

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Recent studies on insect interactions on plants have revealed that herbivorous insects indirectly interact with each other through changes in plant traits following herbivory. However, less attention has been given to plant biomass relative to plant quality in relation to indirect interactions among herbivores. We explored the extent to which the larval food demand of two specialist butterflies (Sericinus montela and Atrophaneura alcinous) explains their interaction on a host plant, Aristolochia debilis. A laboratory experiment showed that plant mass consumption by A. alcinous larvae was 2.6 times greater than that by S. montela. We predicted that A. alcinous, which requires more food, is more vulnerable to food shortages than S. montela. In a cage experiment, an asymmetric interspecific interaction was detected between the two specialist butterflies; S. montela larval density significantly decreased the survival and prolonged the development time of A. alcinous, but A. alcinous density affected neither the survival nor the development time of S. montela. The prediction based on the food requirement was partly supported by the fact that increasing A. alcinous density likely caused a food shortage, which more negatively affected A. alcinous survival than S. montela survival. Conversely, increasing the density of S. montela did not reduce the remaining food quantity, suggesting that the negative effect of S. montela density on A. alcinous was unlikely to be due to food shortage. Although aristolochic acid I, a defensive chemical specific to Aristolochia plants, did not influence the food consumption or growth of either butterfly larva, unmeasured attributes of plant quality may have mediated an indirect interaction between the two butterflies. Consequently, our study suggests that not only the quality but also the quantity of plants should be considered to fully understand the characteristics, such as symmetry, of interspecific interactions among herbivorous insects on the same host plant. [ABSTRACT FROM AUTHOR]

Concurrent exposure to cadmium (Cd) and lead (Pb) is prevalent in the environment, but information on the long-term impacts of complex Cd–Pb exposure on herbivorous insects, especially at low doses, is scant. We studied the effects of complex Cd–Pb exposure (4.06 mg/kg Cd and 12.5 mg/kg Pb) on the growth and food utilization of the herbivorous insect Spodoptera litura for 10 continuous generations. Cd or Pb ingestion, excretion and accumulation by insect at the different developmental stages was determined for ten generations. The weighted scores calculated by the analytic hierarchy process (AHP) on the basis of the parameters of survival, growth and food utilization indicated that complex Cd–Pb exposure had positive impacts on the insects, regardless of generations. Compared with Cd (4.06 mg/kg Cd) and Pb (12.5 mg/kg Pb) alone, complex Cd–Pb exposure showed antagonistic interactions. After exposure to complex Cd–Pb, although larvae significantly increased heavy metal uptake along with the elevated ECD and ECI, insects enhanced heavy metal excretion via the feces and puparium; consequently, heavy metal accumulation in the insect body significantly decreased. With increasing generations, the positive impacts of complex Cd–Pb stress on insects became increasingly obvious, and the uptake of Cd or Pb decreased while the excretion of Cd or Pb increased, which demonstrated that insect tolerance to Cd–Pb exposure at low concentrations increased over generations. [ABSTRACT FROM AUTHOR]

Invertebrate herbivory is a crucial process contributing to the cycling of nutrients and energy in terrestrial ecosystems. While the function of herbivory can decrease with land‐use intensification, the underlying mechanisms remain unclear. We hypothesize that land‐use intensification impacts invertebrate leaf herbivory rates mainly through changes in characteristics of plants and insect herbivores. We investigated herbivory rates (i.e., damaged leaf area) on the most abundant plant species in forests and grasslands and along land‐use intensity gradients on 297 plots in three regions of Germany. To evaluate the contribution of shifts in plant community composition, we quantified herbivory rates at plant species level and aggregated at plant community level. We analyzed pathways linking land‐use intensity, plant and insect herbivore characteristics, and herbivory rates. Herbivory rates at plant species and community level decreased with increasing land‐use intensity in forests and grasslands. Path analysis revealed strong direct links between land‐use intensity and herbivory rates. Particularly at the plant community level, differences in plant and herbivore composition also contributed to changes in herbivory rates along land‐use intensity gradients. In forests, high land‐use intensity was characterized by a larger proportion of coniferous trees, which was linked to reduced herbivory rates. In grasslands, changes in the proportion of grasses, plant fiber content, as well as the taxonomic composition of herbivore assemblages contributed to reduced herbivory rates. Our study highlights the potential of land‐use intensification to impair ecosystem functioning across ecosystems via shifts in plant and herbivore characteristics. De‐intensifying land use in grasslands and reducing the share of coniferous trees in temperate forests can help to restore ecosystem functionality in these systems. [ABSTRACT FROM AUTHOR]

Conventional agriculture has negative impacts on the ecosystems while ecological intensification can ameliorate these effects by enhancing ecological processes. Arbuscular mycorrhizal fungi (AMF) are plant root symbionts that improve access to soil nutrients affecting plant growth and biotic interactions. Agricultural managements differentially affect AMF communities, but how these changes feedback on aboveground plant interactions remains poorly studied. Lettuce (Lactuca sativa) is a common crop severely attacked by Liriomyza huidobrensis (Diptera: Agromizydae), a polyphagous leafminer that has developed resistance to various pesticides, for which managing plant defenses and tolerance represents a feasible option to regulate populations. The aim of this study was to investigate if AMF communities from ecological and conventional management produce differential effects on mycorrhizal interaction, tissue phosphorus content and growth of lettuce plants and on L. huidobrensis oviposition preference. In greenhouse, we compared the effects of soils from farms with conventional and ecological managements from central Argentina on lettuce plants, and exposed them to L. huidobrensis mated females. Mycorrhizal colonization was higher with AMF from ecological than conventional treatments, although plant biomass was lower in treatments with AMF than with sterile soils (Strl), or with soil microorganisms without AMF (MO), in both managements. Phosphorus content was significantly higher in plants with MO and AMF in comparison to Strl, with no difference between managements. Plants grown with AMF from ecological management soils were less attacked by leafminers. Also, the insect preferred to oviposit on plants with higher aerial biomass, and this preference increased in plants with lower P content. [ABSTRACT FROM AUTHOR]

Seasonality is one of the main characteristics of a tropical dry forest that affects the structure of ecological communities. In this context, we evaluated the seasonal diversity of ferns and insects in the tropical dry forest of Morelos, Mexico, to determine whether a relationship exists between the presence of each of these two groups. Hill's numbers indicated differences in the diversity of both groups according to season. In the rainy season, we recorded the highest diversity of ferns, with 6,471 individuals. In contrast, in the dry season, we recorded only 293 individuals. Regarding the insects, we collected 723 individuals in the rainy season and 171 individuals in the dry season. The order Orthoptera was the most abundant (50%). The best-represented functional group according to feeding guild was that of chewing herbivores. Correlation analysis revealed a positive relationship between insect and fern abundances since, for both groups, the minimum abundance was presented in the dry season and the maximum abundance in the rainy season. We recorded 12 orders of insects associated with eight ferns in the rainy season. Seasonal studies that consider different biological groups are necessary to understand how changes in resource availability shape temporal patterns of species diversity. [ABSTRACT FROM AUTHOR]

Plants interact with a large diversity of microbes and insects, both below and above ground. While studies have shown that belowground microbes affect the performance of plants and aboveground organisms, we lack insights into how belowground microbial communities may shape interactions between aboveground pathogens and insects. We investigated how soil microbiomes and aboveground organisms affect plant growth and development, and whether differences in soil microbiomes influence interactions between aboveground organisms. We conducted a growth‐chamber experiment with oak seedlings Quercus robur growing in three soils with similar abiotic soil properties but with distinct natural soil microbiomes. Seedlings were subjected to single or dual attack by powdery mildew Erysiphe alphitoides and aphids Tuberculatus annulatus, either in the presence or absence of prior attack by a free‐feeding caterpillar Phalera bucephala. Soil microbiomes were associated with differences in seedling height, and seedlings with multiple aboveground organisms had more but smaller leaves than healthy seedlings. The soil microbiome affected the severity of powdery mildew infection, and mediated the impact of co‐occurring aboveground organisms on aphid population size. Our study highlights that plant performance is affected by natural soil microbiomes as well as aboveground organisms, and that natural soil microbiomes can affect interactions between pathogens and insects. These findings are important to understand species interactions in natural systems, as well as for practical applications, such as manipulation of soil microbiomes to manage agricultural pests and diseases. [ABSTRACT FROM AUTHOR]

In the field, plants usually have to face the combined effects of abiotic and biotic stresses. In our study, two spring wheat cultivars—Septima and Quintus—were subjected to three water regimes [70%, 50%, and 40% soil water capacity (SWC)], aphid (Metopolophium dirhodum) infestation, or the combination of both stresses, i.e., water deficit (50%, 40% SWC) and aphids. The study has a 2 × 3 × 2 factorial design with three biological replicates. In the present study, the results of proteomic analysis using 2D-DIGE followed by MALDI-TOF/TOF protein identification are presented. Water deficit but also aphid infestation led to alterations in 113 protein spots including proteins assigned to a variety of biological processes ranging from signaling via energy metabolism, redox regulation, and stress and defense responses to secondary metabolism indicating a long-term adaptation to adverse conditions. The absence of specific proteins involved in plant response to herbivorous insects indicates a loss of resistance to aphids in modern wheat cultivars during the breeding process and is in accordance with the “plant vigor hypothesis.” Septima revealed enhanced tolerance with respect to Quintus as indicated by higher values of morphophysiological characteristics (fresh aboveground biomass, leaf length, osmotic potential per full water saturation) and relative abundance of proteins involved in mitochondrial respiration and ATP biosynthesis. [ABSTRACT FROM AUTHOR]

In the field, plants usually have to face the combined effects of abiotic and biotic stresses. In our study, two spring wheat cultivars—Septima and Quintus—were subjected to three water regimes [70%, 50%, and 40% soil water capacity (SWC)], aphid (Metopolophium dirhodum) infestation, or the combination of both stresses, i.e., water deficit (50%, 40% SWC) and aphids. The study has a 2 × 3 × 2 factorial design with three biological replicates. In the present study, the results of proteomic analysis using 2D-DIGE followed by MALDI-TOF/TOF protein identification are presented. Water deficit but also aphid infestation led to alterations in 113 protein spots including proteins assigned to a variety of biological processes ranging from signaling via energy metabolism, redox regulation, and stress and defense responses to secondary metabolism indicating a long-term adaptation to adverse conditions. The absence of specific proteins involved in plant response to herbivorous insects indicates a loss of resistance to aphids in modern wheat cultivars during the breeding process and is in accordance with the “plant vigor hypothesis.” Septima revealed enhanced tolerance with respect to Quintus as indicated by higher values of morphophysiological characteristics (fresh aboveground biomass, leaf length, osmotic potential per full water saturation) and relative abundance of proteins involved in mitochondrial respiration and ATP biosynthesis.

Horizontal gene transfer (HGT) provides an evolutionary shortcut for recipient organisms to gain novel functions. Although reports of HGT in higher eukaryotes are rapidly accumulating, in most cases the evolutionary trajectory, metabolic integration, and ecological relevance of acquired genes remain unclear. Plant cell wall degradation by HGT-derived enzymes is widespread in herbivorous insect lineages. Pectin is an abundant polysaccharide in the walls of growing parts of plants. We investigated the significance of horizontally acquired pectin-digesting polygalacturonases (PGs) of the leaf beetle Phaedon cochleariae. Using a CRISPR/Cas9-guided gene knockout approach, we generated a triple knockout and a quadruple PG-null mutant in order to investigate the enzymatic, biological, and ecological effects. We found that pectin-digestion 1) is exclusively linked to the horizontally acquired PGs from fungi, 2) became fixed in the host genome by gene duplication leading to functional redundancy, 3) compensates for nutrient-poor diet by making the nutritious cell contents more accessible, and 4) facilitates the beetles development and survival. Our analysis highlights the selective advantage PGs provide to herbivorous insects and demonstrate the impact of HGT on the evolutionary success of leaf-feeding beetles, major contributors to species diversity. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Entomology is the property of Chinese Journal of Applied Entomology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant sphingolipids are important membrane components and bioactive molecules in development and defense responses. However, the function of sphingolipids in plant defense, especially against herbivores, is not fully understood. Here, we report that Spodoptera exigua feeding affects sphingolipid metabolism in Arabidopsis, resulting in increased levels of sphingoid long-chain bases, ceramides, and hydroxyceramides. Insect-induced ceramide and hydroxyceramide accumulation is dependent on the jasmonate signaling pathway. Loss of the Arabidopsis alkaline ceramidase ACER increases ceramides and decreases long-chain base levels in plants; in this work, we found that loss of ACER enhances plant resistance to S. exigua and improves response to mechanical wounding. Moreover, acer-1 mutants exhibited more severe root-growth inhibition and higher anthocyanin accumulation than wild-type plants in response to methyl jasmonate treatment, indicating that loss of ACER increases sensitivity to jasmonate and that ACER functions in jasmonate-mediated root growth and secondary metabolism. Transcript levels of ACER were also negatively regulated by jasmonates, and this process involves the transcription factor MYC2. Thus, our findings reveal that ACER is involved in mediating jasmonate-related plant growth and defense and that jasmonates function in regulating the expression of ACER. [ABSTRACT FROM AUTHOR]

The immunotoxicity induced by heavy metals on herbivorous insects reflect the alterations of the susceptibility to entomopathogenic agents in herbivorous insects exposed to heavy metal. In the present study, the susceptibility of gypsy moth larvae to Bacillus thuringiensis under Cd treatment at low and high dosages was investigated, and the gut microbiome-hemolymph metabolome responses that affected larval disease susceptibility caused by Cd exposure were examined. Our results showed that mortality of gypsy moth larvae caused by B. thuringiensis was significantly higher in larvae pre-exposed to Cd stress, and there was a synergistic effect between Cd pre-exposure and bacterial infection. Exposure to Cd significantly decreased the abundance of several probiotics (e.g., Serratia for the low Cd dosage and Weissella, Aeroonas, and Serratia for the high Cd dosage) and increased the abundances of several pathogenic bacteria (e.g., Stenotrophomonas, Gardnerella, and Cutibacterium for the low Cd dosage and Pluralibacter and Tsukamurella for the high Cd dosage) compared to the controls. Moreover, metabolomics analysis indicated that amino acid biosynthesis and metabolism were significantly perturbed in larval hemolymph under Cd exposure at both the low and high dosages. Correlation analysis demonstrated that several altered metabolites in larval hemolymph were significantly correlated with changes in the gut microbial community. The results demonstrate that prior exposure to Cd increases the susceptibility of gypsy moth larvae to B. thuringiensis in a synergistic fashion due to gut microbiota dysbiosis and hemolymph metabolic disorder, and thus microbial-based biological control may be the best pest control strategy in heavy metal-polluted areas.

Allium triquetrum L. (Amaryllidaceae), a bulbiferous monocot, is native to the Mediterranean. It was introduced to Australia in the early 1900s, where it has subsequently become a significant invader of temperate forests throughout south-eastern Australia. Intensive chemical and mechanical control methods can suppress A. triquetrum infestations at the local scale for short periods of time but remain ineffective at sustainably curtailing its invasion at landscape and regional scales. In this context, we undertook field surveys across the Mediterranean (mainland France, Corsica, Sardinia) to determine the feasibility of developing classical biological control solutions for A. triquetrum in Australia. Despite extensive sampling (i.e. 30 surveys at 18 sites over three growing seasons), very few phytophagous arthropod and fungal pathogen taxa were detected on A. triquetrum. The most common arthropod species were the flies Phytomyza gymnostoma and Delia hirticrura, the weevil Oprohinus consputus and the moth Hysterophora maculosana. All identified arthropod taxa were considered generalists, having been found on other plant species, and some are known pests of cultivated Allium species. Twenty-one different fungal isolates were recovered from A. triquetrum, with most considered as saprophytic, secondary/opportunistic pathogens that probably infected already-damaged A. triquetrum leaves. Only four fungal taxa were found to be primary pathogens of A. triquetrum but have been recorded to infect other plant species. None of these enemy taxa were deemed to be suitable candidate biocontrol agents to help manage A. triquetrum invasion in Australia. Future research directions for improved A. triquetrum management in Australia are discussed in this paper. [ABSTRACT FROM AUTHOR]

Agricultural intensification has been implicated in global biodiversity declines. In the European Union, agri‐environmental schemes are designed to address this. For pollinating insects, funding has been provided to sow wildflower mixes. However, previous research indicates that a suite of agricultural weeds are also of great importance to pollinators.Here, we compare the biodiversity associated with the species which are considered harmful to agricultural production and legally deemed as 'injurious' by the United Kingdom 1959 Weeds Act (common ragwort Jacobaea vulgaris, creeping thistle Cirsium arvense, spear thistle C. vulgare, curled dock Rumex crispus and broadleaved dock R. obtusifolius), with plant species recommended for pollinator‐targeted agri‐environmental options.In our field study, the abundance and diversity of pollinators visiting the weed species averaged twice that of the recommended plants and included the main insect orders (Coleoptera, Diptera, Hymenoptera and Lepidoptera). This relationship was also seen in a meta‐analysis of literature data, which indicates that fourfold more flower‐visitor species and fivefold more conservation‐listed species are associated with the weeds. Additionally, the literature shows that twice the number of herbivorous insect species are associated with these plants.We suggest that several factors are responsible for this pattern. Injurious weed species are widely distributed, their flower morphology allows access to a wide variety of pollinator species, and they produce, on average, four times more nectar sugar than the recommended plant species.Freedom of information requests to public bodies such as local councils, Natural England and Highways England indicate that c. £10 million per year is spent controlling injurious weeds. Meanwhile, the cost of the four pollinator‐targeted agri‐environmental options in the United Kingdom exceeds £40 m annually.Synthesis and applications. Our results clearly show that weeds have an underappreciated value to biodiversity. Unfortunately, current UK agricultural policy encourages neither land sparing for nor land sharing with weeds. The UK government is, however, currently committed to overhauling agricultural payments to encourage more wildlife‐ and climate‐friendly practices. Thus, the challenge of reconciling the conflicts between agricultural production and these native and biodiverse species should be a renewed priority to land managers, researchers and policymakers. [ABSTRACT FROM AUTHOR]

Insoluble proanthocyanidins are reported as plant defence compounds against herbivorous insects. This is the first report to demonstrate the occurrence of insoluble proanthocyanidins in plants of the Polygonaceae family. In this study, we identified a mutant Tartary buckwheat (Fagopyrum tataricum) cultivar, 'Hokkai T10', that lacks insoluble proanthocyanidins accumulation in leaves and shows a role in defence against common cutworm (Spodoptera litura Fabricius). We did not detect insoluble proanthocyanidins in p‐dimethylaminocinnamaldehyde stain in 'Hokkai T10'. The expression of the trait should be regulated by at least one recessive gene named iPA. The leaves of 'Hokkai T10' were ingested in larger amount by S. litura than the wild type. This fact supports the hypothesis that insoluble proanthocyanidins have a role in protection against insects. This is the first report to demonstrate a resistance role of insoluble proanthocyanidins using insect preference. In addition, the germination rate of 'Hokkai T10' was significantly higher than wild type; indicating to show firstly the effects of insoluble proanthocyanidins on seed germination. [ABSTRACT FROM AUTHOR]

Concurrent exposure to cadmium (Cd) and lead (Pb) is prevalent in the environment, but information on the long-term impacts of complex Cd–Pb exposure on herbivorous insects, especially at low doses, is scant. We studied the effects of complex Cd–Pb exposure (4.06 mg/kg Cd and 12.5 mg/kg Pb) on the growth and food utilization of the herbivorous insect Spodoptera litura for 10 continuous generations. Cd or Pb ingestion, excretion and accumulation by insect at the different developmental stages was determined for ten generations. The weighted scores calculated by the analytic hierarchy process (AHP) on the basis of the parameters of survival, growth and food utilization indicated that complex Cd–Pb exposure had positive impacts on the insects, regardless of generations. Compared with Cd (4.06 mg/kg Cd) and Pb (12.5 mg/kg Pb) alone, complex Cd–Pb exposure showed antagonistic interactions. After exposure to complex Cd–Pb, although larvae significantly increased heavy metal uptake along with the elevated ECD and ECI, insects enhanced heavy metal excretion via the feces and puparium; consequently, heavy metal accumulation in the insect body significantly decreased. With increasing generations, the positive impacts of complex Cd–Pb stress on insects became increasingly obvious, and the uptake of Cd or Pb decreased while the excretion of Cd or Pb increased, which demonstrated that insect tolerance to Cd–Pb exposure at low concentrations increased over generations.

Urban forests are critically important for providing ecosystem services to rapidly expanding urban populations, but their health is threatened by invasive insect herbivores. To protect urban forests against invasive insects and support future delivery of ecosystem services, we must first understand the factors that affect insect density across urban landscapes. This study explores how a variety of environmental factors that vary across urban habitats influence density of invasive insects. Specifically, we evaluate how vegetational complexity, distance to buildings, impervious surface, canopy temperature, host availability and density of co-occurring herbivores impact three invasive pests of elm trees: the elm leaf beetle (Xanthogaleruca luteola), the elm flea weevil (Orchestes steppensis) and the elm leafminer (Fenusa ulmi). Insect responses to these factors were species-specific, and all environmental factors were associated with density of at least one pest species except for distance to buildings. Elm leafminer density decreased with higher temperatures and was influenced by an interaction between vegetational complexity and impervious surface. Elm flea weevil density increased with greater host availability, and elm leaf beetle density increased with higher temperatures. Both elm leaf beetle and elm flea weevil density decreased with greater leafminer density, suggesting that insect density is mediated by species interactions. These findings can be used to inform urban pest management and tree care efforts, making urban forests more resilient in an era when globalization and climate change make them particularly vulnerable to attack. [ABSTRACT FROM AUTHOR]

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Intensification of urbanization has been shown to be associated with taxonomic and functional modifications of biological communities, leading to changes in trophic interactions. These changes may reduce the delivery of ecosystem services provided by urban ecosystems. For instance, predation on herbivorous insects is an important ecological process operating in urban biological communities. Specifically, on one hand, herbivorous insects serve as food resources for many organisms, and on the other hand predation on herbivorous insects may reduce pest populations on urban vegetation. In this study, we assessed the relationship between urbanization intensity and bird and arthropod predation pressure on herbivorous insects across the streetscape of Xalapa (Mexico), a Neotropical city with half a million people immersed in a cloud forest context. We exposed dummy caterpillar models at 16 sites across the streetscape and two sites in a peri-urban cloud forest patch, comprising a wide range of urbanization intensities. We observed that in streets where the proportion of built cover was higher, dummy caterpillars’ attack probability was substantially lower. Moreover, we observed that caterpillars were most often attacked by arthropods (62.41%), followed by birds (21.53%), independent of built cover. Our study provides evidence that built cover surrounding streets may negatively influence the interactions between herbivorous insects and their natural enemies.

Herbivorous insect communities are structured by multiple processes operating locally (e.g. bottom–up effects of plants) and regionally (e.g. dispersal limitation). Although the relative strength of these processes has been well documented, how it varies in time is less understood, especially in relation with the temporal dynamics of plant communities. If temporal turnover of local plant species composition is too rapid for insect community assembly to keep up with, bottom–up effects are expected to be weak. Here, in plant and herbivorous insect communities in Japanese grasslands, we studied how the relative importance of local (bottom–up effects of plants, structures of plant communities and top–down effects of predators) and regional (dispersal limitation) processes varies over the growing season. In addition, we tested the hypothesis that larger temporal turnover of plant species composition is related to the weaker bottom–up effects, that is, the lower explanation power of plant communities for insect communities. We found that, throughout the growing season, the insect species composition was mainly explained by local variables (plant species composition, vegetation height and predator abundance), and their explanation power was higher during later phases of the season (late summer). Furthermore, the variation not explained by plant species composition was correlated with the degree of temporal turnover of plants, suggesting that insect communities failed to track the temporal turnover of plant species. These results were pronounced when we focused on leaf sucker insects, whose host plant range is presumably more limited. We conclude that herbivorous insect communities are mainly regulated by local processes, especially bottom–up effects from plants, while stochasticity may have played a role in early phases of the season. Furthermore, we underscore the importance of considering relative time scale of community assembly and environmental shifts, especially in systems characterized by dynamic changes. [ABSTRACT FROM AUTHOR]

Dichroplus maculipennis is one of the most damaging grasshoppers of wetlands. We investigated their feeding behavior in relation to the most abundant plants of Patagonian wetlands. Results showed that D. maculipennis was able to select its food resources and displayed a mixed diet. The most consumed plant was Taraxacum officinale, which contains a large amount of protein and water. However, consumption decreased when offered simultaneously with Juncus balticus and Holcus lanatus. Therefore, diet varied according to the supply of plants that were offered. In future studies, it would be interesting to analyze the influence of diet on performance. [ABSTRACT FROM AUTHOR]

The study of herbivorous insects underpins much of the theory that concerns the evolution of species interactions. In particular, Pieridae butterflies and their host plants have served as a model system for studying evolutionary arms races. To learn more about the coevolution of these two clades, we reconstructed ancestral ecological networks using stochastic mappings that were generated by a phylogenetic model of host‐repertoire evolution. We then measured if, when, and how two ecologically important structural features of the ancestral networks (modularity and nestedness) evolved over time. Our study shows that as pierids gained new hosts and formed new modules, a subset of them retained or recolonised the ancestral host(s), preserving connectivity to the original modules. Together, host‐range expansions and recolonisations promoted a phase transition in network structure. Our results demonstrate the power of combining network analysis with Bayesian inference of host‐repertoire evolution to understand changes in complex species interactions over time. [ABSTRACT FROM AUTHOR]

[Display omitted] • BmGr6 and BmGr9 are responsible for host plant selection by silkworm larvae. • The two Grs serve as receptors for chlorogenic acid and isoquercitrin in HEK cells. • The two Grs confer the maxillary palp ultrahigh sensitivity to these compounds. • BmGr6- and BmGr9-KO larvae lost the ability to recognize host leaves. Herbivorous insects can identify their host plants by sensing plant secondary metabolites as chemical cues. We previously reported the two-factor host acceptance system of the silkworm Bombyx mori larvae. The chemosensory neurons in the maxillary palp (MP) of the larvae detect mulberry secondary metabolites, chlorogenic acid (CGA), and isoquercetin (ISQ), with ultrahigh sensitivity, for host plant recognition and feeding initiation. Nevertheless, the molecular basis for the ultrasensitive sensing of these compounds remains unknown. In this study, we demonstrated that two gustatory receptors (Grs), BmGr6 and BmGr9, are responsible for sensing the mulberry compounds with attomolar sensitivity for host plant recognition by silkworm larvae. Calcium imaging assay using cultured cells expressing the silkworm putative sugar receptors (BmGr4-10) revealed that BmGr6 and BmGr9 serve as receptors for CGA and ISQ with attomolar sensitivity in human embryonic kidney 293T cells. CRISPR/Cas9-mediated knockout (KO) of BmGr6 and BmGr9 resulted in a low probability of making a test bite of the mulberry leaves, suggesting that they lost the ability to recognize host leaves. Electrophysiological recordings showed that the loss of host recognition ability in the Gr-KO strains was due to a drastic decrease in MP sensitivity toward ISQ in BmGr6-KO larvae and toward CGA and ISQ in BmGr9-KO larvae. Our findings have revealed that the two Grs, previously considered to be sugar receptors, are molecules responsible for detecting plant phenolics in host plant recognition. [ABSTRACT FROM AUTHOR]

Outbreaks of eastern spruce budworm (Choristoneura fumiferana; hereafter SBW) are a major natural disturbance in coniferous forests of eastern North America. These outbreaks provide a superabundant source of food for insectivorous birds. Three species, referred to as budworm-linked warblers, exhibit strong positive numerical responses to early increases of SBW density: Tennessee Warbler (Leiothlypis peregrina), Cape May Warbler (Setophaga tigrina), and Bay-breasted Warbler (S. castanea). Their abundance increases even before defoliation is visible from aerial surveys. Budworm-linked warblers may detect new epicenters of SBW outbreaks through natal dispersal, as this movement is typically much more extensive than subsequent (breeding dispersal) movements. Our main objectives were, thus, (1) to determine whether sudden increases in the abundance of budworm-linked warblers could be used to detect early stages of SBW outbreaks, and (2) to examine age-specific responses of budworm-linked warblers to local and landscape-level habitat characteristics, in order to investigate the potential role of natal dispersal in the detection of new epicenters. To do so, we estimated the abundance of each species of budworm-linked warbler in 75 study plots sampling a gradient of SBW density and related them to 7 stand variables and landscape metrics with generalized additive mixed models. We also compared the responses of yearling (second-year; SY) and older (after-second-year; ASY) individuals to the density of SBW larvae and habitat variables at different spatial scales. We captured 31 Tennessee Warblers, 27 Cape May Warblers, and 57 Bay-breasted Warblers. The abundance of all three species of budworm-linked warblers increased with SBW larval density, but the numerical response of Bay-breasted Warbler was initiated earlier and it varied with age. SY individuals tended to be associated with stands supporting lower larval densities than ASY individuals and, as suggested by other authors, Bay-breasted Warbler appeared to be more efficient at exploiting SBW larvae at low density. For that reason, this species represents an early indicator of stands undergoing SBW outbreaks and we propose to use its abundance as an indicator to orient labour-intensive ground surveys of SBW larvae.

Abstract Under habitat loss and fragmentation, the intensity of local ecological processes involving species interactions changes pervasively, accelerating local species extinctions, and disrupting essential ecosystem functions. We addressed this issue by examining the direct population drivers of apex predators (five felid species), armadillo mesopredators, leafcutter ants (Atta sexdens and Atta cephalotes), and the indirect effects mediated by their inter‐trophic relationships in a ~25‐yr‐old land‐bridge island system formed by a hydroelectric dam in the Central Amazon. These trophic groups and pioneer tree abundance were surveyed across 34 variable‐sized islands and three continuous forest sites. Leafcutter populations were characterized in relation to their occurrence, colony density, and proportion of inactive colonies, and for each leafcutter response, we considered the direct and/or indirect effects of forest area on each trophic group. Leafcutter occupancy was best explained by the direct model, colony density by either the direct or the indirect model, and proportion of inactive colonies by an indirect model via the effects of pioneer tree abundance. The direct forest area effects were positive for apex predators and leafcutter occupancy, but negative for armadillos and pioneer trees. Yet leafcutter colony density declined in increasingly larger forest areas. The absence or low abundance of apex predators on small islands released armadillo hyper‐abundance, which contrary to expectation from top‐down control, covaried positively with leafcutter colony density. Finally, the indirect model showed that leafcutter colonies were more active under higher pioneer tree abundances. That leafcutter density increases on smaller islands whenever present is likely attributed to the hyper‐abundance of pioneer plants and canopy gaps. Although apex predators apparently suppressed armadillos, the remaining fraction of the food web seems to be controlled by bottom‐up mechanisms most likely related the overall low foliage palatability typical of wet evergreen forests. Our findings can be used to inform the long‐term viability of forest ecosystems affected by hydropower development in lowland Amazonia.

Semi-natural grasslands in Japan have decreased due to management abandonment and urbanization over the last 100 years, but they remain in suburban areas in addition to rural areas. Because suburban grasslands have various land-use histories and disturbance regimes, plant and herbivorous insect communities are likely to differ among grassland types. To identify grasslands with high conservation value, we conducted a comprehensive survey of grasshoppers and plants in 150 grasslands with 5 grassland types differing in land-use history and current management in northern Chiba prefecture, Japan. We then analyzed the association of the distributions of grasshopper and plant species compositions. Our results showed that grasshoppers were classified into habitat specialists and generalists. Three out of four habitat specialists were almost exclusively found in semi-natural grasslands and vacant lots, while habitat generalists were commonly observed at the cropland margins. This habitat specialist–generalist distribution gradient corresponded well to that found in plant communities, which was probably due to current disturbance regimes. We suggest that vacant lots as well as semi-natural grasslands have high conservation value for grassland organisms of various taxa in suburban areas, and grasshoppers are candidate indicator species for monitoring grassland environments. [ABSTRACT FROM AUTHOR]

Under habitat loss and fragmentation, the intensity of local ecological processes involving species interactions changes pervasively, accelerating local species extinctions, and disrupting essential ecosystem functions. We addressed this issue by examining the direct population drivers of apex predators (five felid species), armadillo mesopredators, leafcutter ants (Atta sexdens and Atta cephalotes), and the indirect effects mediated by their inter‐trophic relationships in a ~25‐yr‐old land‐bridge island system formed by a hydroelectric dam in the Central Amazon. These trophic groups and pioneer tree abundance were surveyed across 34 variable‐sized islands and three continuous forest sites. Leafcutter populations were characterized in relation to their occurrence, colony density, and proportion of inactive colonies, and for each leafcutter response, we considered the direct and/or indirect effects of forest area on each trophic group. Leafcutter occupancy was best explained by the direct model, colony density by either the direct or the indirect model, and proportion of inactive colonies by an indirect model via the effects of pioneer tree abundance. The direct forest area effects were positive for apex predators and leafcutter occupancy, but negative for armadillos and pioneer trees. Yet leafcutter colony density declined in increasingly larger forest areas. The absence or low abundance of apex predators on small islands released armadillo hyper‐abundance, which contrary to expectation from top‐down control, covaried positively with leafcutter colony density. Finally, the indirect model showed that leafcutter colonies were more active under higher pioneer tree abundances. That leafcutter density increases on smaller islands whenever present is likely attributed to the hyper‐abundance of pioneer plants and canopy gaps. Although apex predators apparently suppressed armadillos, the remaining fraction of the food web seems to be controlled by bottom‐up mechanisms most likely related the overall low foliage palatability typical of wet evergreen forests. Our findings can be used to inform the long‐term viability of forest ecosystems affected by hydropower development in lowland Amazonia. [ABSTRACT FROM AUTHOR]

Herbivore‐induced plant volatiles play important ecological roles in defense against stresses. However, if and which volatile(s) are involved in the plant–plant communication in response to herbivorous insects in tea plants remains unknown. Here, plant–plant communication experiments confirm that volatiles emitted from insects‐attacked tea plants can trigger plant resistance and reduce the risk of herbivore damage by inducing jasmonic acid (JA) accumulation in neighboring plants. The emission of six compounds was significantly induced by geometrid Ectropis obliqua, one of the most common pests of the tea plant in China. Among them, (E)‐4,8‐dimethyl‐1,3,7‐nonatriene (DMNT) could induce the accumulation of JA and thus promotes the resistance of neighboring intact plants to herbivorous insects. CsCYP82D47 was identified for the first time as a P450 enzyme, which catalyzes the final step in the biosynthesis of DMNT from (E)‐nerolidol. Down‐regulation of CsCYP82D47 in tea plants resulted in a reduced accumulation of DMNT and significantly reduced the release of DMNT in response to the feeding of herbivorous insects. The first evidence for plant–plant communication in response to herbivores in tea plants will help to understand how plants respond to volatile cues in response to herbivores and provide new insight into the role(s) of DMNT in tea plants. Plant–plant communication is of great importance as it allows plants and the partners they interact with to tune their growth and defense. However, if and which volatile(s) are involved in the plant–plant communication in response to herbivorous insects in tea plants remains unknown. Here, we provide the first evidence for plant–plant communication via inducible volatiles in response to herbivores damage in tea plants, and CsCYP82D47 was identified for the first time as a P450 enzyme involved in the formation of herbivore‐induced DMNT, which plays a key role(s) in priming plant defense against herbivores of their neighbors. The knowledge will help to understand how plants respond to volatile cues in response to herbivores and provide new insight into the role(s) and formation of DMNT in tea plants. [ABSTRACT FROM AUTHOR]

Using 60 Palaearctic species of the leafhopper genus Macropsis as an example, the contribution of sympatric and allopatric speciation to the origin of herbivorous insect biodiversity was studied. According to the previously reconstructed evolutionary scenarios, in the temperate zone of the Palaearctic Region the genus Macropsis probably dispersed from east to west and formed 10 natural groups, with species within each group being similar both in morphological traits and in host specialization. The hypothetical speciation modes for each group can be largely inferred from geography. If related species replace each other in different zoogeographic regions, they are likely to have arisen as the result of allopatric speciation. If the species show overlapping distributions and live on the same host plant, they must have originated in allopatry and become secondarily sympatric due to subsequent dispersal. Finally, if related species have strongly overlapping ranges and populate similar habitats but differ in host specializations, this may indicate their origin as the result of sympatric speciation due to host plant shifts. For 31 species (51.7%), allopatric speciation seems to be the most likely or even the only possible scenario, whereas for 20 species (33.3%), the hypothesis of sympatric speciation is either convincingly substantiated or at least quite feasible. The origins of the remaining 9 species (15%) remain unknown. Therefore, sympatric speciation is not a rare phenomenon in Macropsis, but it certainly does not predominate over the allopatric mode. Thus, even within the same genus of herbivorous insects, speciation can occur in different ways: in the allopatric mode, when a host plant shift is possible but not essential, and in the sympatric mode, when divergence is triggered by the host shift. Cases of intraspecific differentiation, which can be considered as initial stages of speciation, are also discussed. These are allopatric color forms associated with the same host plant, allopatric color forms associated with different plants and, finally, forms living on different sympatric or allopatric hosts but showing no difference in coloration. It is shown that divergence is not always caused by transition to a new host plant even in specialized herbivores. [ABSTRACT FROM AUTHOR]

Compared with the highly diverse microbiota of leaves, herbivorous insects exhibit impoverished gut microbial communities. Research to date has focused on the bacterial component of these gut microbiomes, neglecting the fungal component. As caterpillar gut bacterial microbiomes are derived strongly from their diet, we hypothesized that their mycobiomes would reflect the host leaf mycobiomes. Using the ITS2 rDNA and V5–V6 16S rRNA gene regions for DNA metabarcoding of caterpillar gut and host leaf sample pairs we compared their mycobiome genus diversity and compositions and identified genera associated with caterpillar guts. Leaves and caterpillar guts harbored different mycobiomes with quite low qualitative similarity (Jaccard index = 38.03%). The fungal genera most significantly associated with the caterpillar gut included Penicillium , Mucor and unidentified Saccharomycetales , whereas leaf-associated genera included Holtermanniella , Gibberella (teleomorph of Fusarium) and Seimatosporium. Although caterpillar gut and leaf mycobiomes had similar genus richness overall, this indicator was not correlated for individual duplets. Moreover, as more samples entered the analysis, mycobiome richness increased more rapidly in caterpillar guts than in leaves. The results suggest that the mycobiota of the caterpillar gut differs from that of their feeding substrate; further, the mycobiomes appear to be richer than the well-studied bacterial microbiotas. [ABSTRACT FROM AUTHOR]

Seminatural grasslands are important biodiversity hotspots, but they are increasingly degraded by intensive agriculture. Grassland restoration is considered to be promising in halting the ongoing loss of biodiversity, but this evaluation is mostly based on plant communities. Insect herbivores contribute substantially to grassland biodiversity and to the provisioning of a variety of ecosystem functions. However, it is unclear how they respond to different measures that are commonly used to restore seminatural grasslands from intensively used agricultural land. We studied the long‐term success of different restoration techniques, which were originally targeted at reestablishing seminatural grassland plant communities, for herbivorous insect communities on taxonomic as well as functional level. Therefore, we sampled insect communities 22 yr after the establishment of restoration measures. These measures ranged from harvest and removal of biomass to removal of the topsoil layer and subsequent seeding of plant propagules. We found that insect communities in restored grasslands had higher taxonomic and functional diversity compared to intensively managed agricultural grasslands and were more similar in composition to target grasslands. Restoration measures including topsoil removal proved to be more effective, in particular in restoring species characterized by functional traits susceptible to intensive agriculture (e.g., large‐bodied species). Our study shows that long‐term success in the restoration of herbivorous insect communities of seminatural grasslands can be achieved by different restoration measures and that more invasive approaches that involve the removal of the topsoil layer are more effective. We attribute these restoration successes to accompanying changes in the plant community, resulting in bottom‐up control of the herbivore community. Our results are of critical importance for management decisions aiming to restore multi‐trophic communities, their functional composition and consequently the proliferation of ecosystem functions. [ABSTRACT FROM AUTHOR]

Increased frequency and severity of drought, as a result of climate change, is expected to drive critical changes in plant–insect interactions that may elevate rates of tree mortality. The mechanisms that link water stress in plants to insect performance are not well understood. Here, we build on previous reviews and develop a framework that incorporates the severity and longevity of drought and captures the plant physiological adjustments that follow moderate and severe drought. Using this framework, we investigate in greater depth how insect performance responds to increasing drought severity for: (i) different feeding guilds; (ii) flush feeders and senescence feeders; (iii) specialist and generalist insect herbivores; and (iv) temperate versus tropical forest communities. We outline how intermittent and moderate drought can result in increases of carbon‐based and nitrogen‐based chemical defences, whereas long and severe drought events can result in decreases in plant secondary defence compounds. We predict that different herbivore feeding guilds will show different but predictable responses to drought events, with most feeding guilds being negatively affected by water stress, with the exception of wood borers and bark beetles during severe drought and sap‐sucking insects and leaf miners during moderate and intermittent drought. Time of feeding and host specificity are important considerations. Some insects, regardless of feeding guild, prefer to feed on younger tissues from leaf flush, whereas others are adapted to feed on senescing tissues of severely stressed trees. We argue that moderate water stress could benefit specialist insect herbivores, while generalists might prefer severe drought conditions. Current evidence suggests that insect outbreaks are shorter and more spatially restricted in tropical than in temperate forests. We suggest that future research on the impact of drought on insect communities should include (i) assessing how drought‐induced changes in various plant traits, such as secondary compound concentrations and leaf water potential, affect herbivores; (ii) food web implications for other insects and those that feed on them; and (iii) interactions between the effects on insects of increasing drought and other forms of environmental change including rising temperatures and CO2 levels. There is a need for larger, temperate and tropical forest‐scale drought experiments to look at herbivorous insect responses and their role in tree death. [ABSTRACT FROM AUTHOR]

Woody encroachment in grasslands has become increasingly problematic globally. Grazing by domestic animals can facilitate woody encroachment by reducing competition from herbaceous plants and fire frequency. Herbivorous insects and parasitic plants can each exert forces that result in the natural biological control of encroaching woody plants through reducing seeding of their host woody plants. However, the interplay of grazing and dynamics of herbivorous insects or parasitic plants, and its effects on the potential biological control of woody encroachment in grasslands remains unclear. We investigated the flower and pod damage by herbivorous insects, and the infection rates of a parasitic plant on the shrub Caragana microphylla, which is currently encroaching in Inner Mongolia Steppe, under different grazing management treatments (33-year non-grazed, 7-year non-grazed, currently grazed). Our results showed that Caragana biomass was highest at the currently grazed site, and lowest at the 33-year non-grazed site. Herbaceous plant biomass followed the opposite pattern, suggesting that grazing is indeed facilitating the encroachment of Caragana plants in Inner Mongolia Steppe. Grazing also reduced the abundance of herbivorous insects per Caragana flower, numbers of flowers and pods damaged by insect herbivores, and the infection rates of the parasitic plant on Caragana plants. Our results suggest that grazing may facilitate woody encroachment in grasslands not only through canonical mechanisms (e.g. competitive release via feeding on grasses, reductions in fires, etc.), but also by limiting natural biological controls of woody plants (herbivorous insects and parasitic plants). Thus, management efforts must focus on preventing overgrazing to better protect grassland ecosystems from woody encroachment.

The intricate relationship between herbivorous insects and plants has evolved over millions of years, central to this dynamic interaction are salivary proteins (SPs), which mediate key processes ranging from nutrient acquisition to plant defense manipulation. SPs, sourced from salivary glands, intestinal regurgitation or acquired through horizontal gene transfer, exhibit remarkable functional versatility, influencing insect development, behavior, and adhesion mechanisms. Moreover, SPs play pivotal roles in modulating plant defenses, to induce or inhibit plant defenses as elicitors or effectors. In this review, we delve into the multifaceted roles of SPs in herbivorous insects, highlighting their diverse impacts on insect physiology and plant responses. Through a comprehensive exploration of SP functions, this review aims to deepen our understanding of plant-insect interactions and foster advancements in both fundamental research and practical applications in plant-insect interactions., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 Published by Elsevier Ltd.)

Elevated ground-level ozone (O3) reduced C-based defense chemicals; however, severe grazing damages were found in leaves grown in the low O3 condition of a free air O3-concentration enrichment (O3-FACE) system. To explain this phenomenon, this study investigates the role of BVOCs (biogenic volatile organic compounds) as signaling compounds for insect herbivores. BVOCs act as scents for herbivore insects to locate host plants, while some BVOCs show high reactivity to O3, inducing changes in the composition of BVOCs in atmospheres with elevated O3. To assess the aforementioned phenomenon, profiles of BVOCs emitted from birch (Betula platyphylla var. japonica Hara) leaves were analyzed ex situ, and Y-tube insect preference tests were conducted in vitro to study the insect olfactory response. The assays were conducted in June and August or September, according to the life cycle of the adult alder leaf beetle Agelastica coerulea Baly (Coleoptera: Chrysomelidae). The Y-tube tests revealed that the leaf beetles were attracted to BVOCs, and O3 per se had neither an attractant nor a repellent effect. BVOCs became less attractant when mixed with highly concentrated O3 (>80 ppb). About 20% of the total BVOCs emitted were highly O3-reactive compounds, such as β-ocimene. The results suggest that BVOCs emitted from the birch leaves can be altered by elevated O3, thus potentially reducing the attractiveness of leaves to herbivorous insects searching for food. [ABSTRACT FROM AUTHOR]