Host Leaf Research Articles

Montmorillonite nanoclay triggers immunity responses in wheat against Puccinia striiformis f. sp. tritici, and suppresses uredospore germination

Puccinia striiformis f. sp. tritici causes the important disease, yellow rust of wheat (Triticum aestivum). Montmorillonite nanoclay (MNC) is naturally occurring and biodegradable. This study assessed in vitro anti-germination effects of MNC on P. striiformis uredospores. Application of MNC at 150 mg L-1 completely inhibited uredospore germination, and MNC at 100 mg L-1 reduced yellow rust severity in wheat plants by 89%. Expression of defense-related genes was increased after MNC treatment at 100 mg L-1, by 5.23-fold for jasmonate and ethylene-responsive factor 3 (JERF3), 4.89-fold for chitinase class II (CHI II), and 2.37-fold for pathogenesis-related protein 1 (PR1). Applying MNC at 100 mg L-1 also activated the antioxidant enzymes POD to 62.1 unit min-1 g-1 fresh wt, PPO to 21.6 units min-1 g-1 fresh wt, and CAT to 36.6 units min-1 g-1 fresh wt. MNC also enhanced phenolic content in wheat leaves (to 1489.53 mg 100 g-1 f. wt), and reduced lipid oxidation levels (to 5.6 μmol MDA g-1 fresh wt). MNC at 100 mg L-1 also mitigated damaging effects of P. striiformis infections on host leaf cell ultrastructure, increased leaf photosynthetic pigments, and increased wheat plant growth. These results show that MNC has potential as a natural control agent for yellow rust of wheat, although field testing of MNC is necessary before this material can be recommended for wheat production.

PcLRR-RK3, an LRR receptor kinase is required for growth and in-planta infection processes in Phytophthora capsici

ABSTRACT Receptor protein kinases (RPKs) critically provide the basic infrastructure to sense, perceive, and conduct the signalling events at the cell surface of organisms. The importance of LRR-RLKs has been well studied in plants, but much less information has been reported in oomycetes. In this work, we have silenced the PcLRR-RK3 and characterised its functional importance in Phytophthora capsici. PcLRR-RK3 was predicted to encode signal peptides, leucine-rich repeats, transmembrane, and kinase domains. PcLRR-RK3-silenced transformants showed impaired colony growth, decreased deformed sporangia, and reduced zoospores count. The mycelium of silenced transformants did not penetrate within the host tissues and showed defects in the pathogenicity of P. capsici. Interestingly, gene silencing also weakens the ability of zoospores germination and penetration into host tissues and fails to produce necrotic lesions. Furthermore, PcLRR-RK3 localisation was found to be the plasma membrane of the cell. Altogether, our results revealed that PcLRR-RK3 was required for the regulation of vegetative growth, zoospores penetration, and establishment into host leaf tissues.

Isolation and identification of phyllosphere bacteria from three different crops

The phyllosphere represents the habitat provided by the aboveground parts of plants. There have been few studies on the phyllosphere of plants. A large number of microbes are associated with the phyllosphere, where bacteria are the most dominant. The main objective of the present study was to isolate phyllosphere bacteria from three different crops cultivated in the Jaffna district. Phyllosphere bacteria were isolated by washing the host leaf and plating on nutrient agar media. Two different phyllosphere bacteria, namely, Pseudomonas putida and Staphylococcus equorum and two different species of the genus Bacillus (B. cereus and B. pumilus)were isolated from Zea mays. Staphylococcus epidermis and two different species of Bacillus (B. cereus and B. subtilis) were isolated from Solanum lycopersicum. Two different phyllosphere bacteria, namely, Lactobacillus brevis and Micrococcus luteus, and three different species of Bacillus (B. subtilis, B. mycoides and B. licheniformis) were isolated from Brassica oleracea var. capitata. The isolates were identified based on colony morphological characteristics and biochemical tests.

A phytoplasma effector destabilizes chloroplastic glutamine synthetase inducing chlorotic leaves that attract leafhopper vectors

Leaf yellowing is a well-known phenotype that attracts phloem-feeding insects. However, it remains unclear how insect-vectored plant pathogens induce host leaf yellowing to facilitate their own transmission by insect vectors. Here, we report that an effector protein secreted by rice orange leaf phytoplasma (ROLP) inhibits chlorophyll biosynthesis and induces leaf yellowing to attract leafhopper vectors, thereby presumably promoting pathogen transmission. This effector, designated secreted ROLP protein 1 (SRP1), first secreted into rice phloem by ROLP, was subsequently translocated to chloroplasts by interacting with the chloroplastic glutamine synthetase (GS2). The direct interaction between SRP1 and GS2 disrupts the decamer formation of the GS2 holoenzyme, attenuating its enzymatic activity, thereby suppressing the synthesis of chlorophyll precursors glutamate and glutamine. Transgenic expression of SRP1 in rice plants decreased GS2 activity and chlorophyll precursor accumulation, finally inducing leaf yellowing. This process is correlated with the previous evidence that the knockout of GS2 expression in rice plants causes a similar yellow chlorosis phenotype. Consistently, these yellowing leaves attracted higher numbers of leafhopper vectors, caused the vectors to probe more frequently, and presumably facilitate more efficient phytoplasma transmission. Together, these results uncover the mechanism used by phytoplasmas to manipulate the leaf color of infected plants for the purpose of enhancing attractiveness to insect vectors.

EFFECT OF CULTURE MEDIA ON GROWTH AND SPORULATION OF Colletotrichum lindemuthianum (SACC AND MAGN) ISOLATES CAUSING ANTHRACNOSE OF FIELD BEAN

Anthracnose (Colletotrichum lindemuthianum) is the most important fungal disease affecting field bean. Growth and sporulation of thirty six isolates of C. lindemuthianum collected from five agro-climatic zones of Andhra Pradesh was evaluated in the year 2017-18 on four different solid and liquid culture media. Results revealed that potato dextrose agar was the best for both radial growth (66.74 mm) and dry mycelial weight (264.74 mg), whereas, host leaf extract agar significantly supported more sporulation 7.3 x104. The least mycelia growth of 39.32 mm, dry mycelial weight of 234.70 mg and sporulation 2.9 x104 were observed on Sabourband’s agar. Among the different isolates, Cl-33 grew fast with mycelial growth and sporulation (78.86 mm and 8.4x104) and Cl-32 produced the highest dry mycelial weight 266.75 mg). The least radial growth (31.35 mm), the lowest sporulation (4.1 x104) and lowest mycelial dry weight (227.75 mg) was recorded in CI-28, CI-1 and CI 17, respectively. Mean conidial length of 36 isolates ranged from 11.87 to 13.03 µm with the maximum length (13.03 µm) recorded in host leaf extract agar, while minimum was recorded in oat meal agar. Width of conidia varied from 3.59 to 4.11 µm on different media and 3.53 to 4.23 µm in different isolates.The growth phase study revealed that increase in the dry mycelial weight of fungus upto 15 days of incubation and growth declined from 17th day onwards.

Evolution of larval gregariousness is associated with host plant specialisation, but not host morphology, in Heliconiini butterflies.

Insect herbivores, such as lepidopteran larvae, often have close evolutionary relationships with their host plants, with which they may be locked in an evolutionary arms race. Larval grouping behaviour may be one behavioural adaptation that improves host plant feeding, but aggregation also comes with costs, such as higher competition and limited resource access. Here, we use the Heliconiini butterfly tribe to explore the impact of host plant traits on the evolution of larval gregariousness. Heliconiini almost exclusively utilise species from the Passifloraceae as larval host plants. Passifloraceae display incredible diversity in leaf shape and a range of anti-herbivore defences, suggesting they are responding to, and influencing, the evolution of Heliconiini larvae. By analysing larval social behaviour as both a binary (solitary or gregarious) and categorical (increasing larval group size) trait, we revisit the multiple origins of larval gregariousness across Heliconiini. We investigate whether host habitat, leaf defences and leaf size are important drivers of, or constraints on, larval gregariousness. Whereas our data do not reveal links between larval gregariousness and the host plant traits included in this study, we do find an interaction between host plant specialisation and larval behaviour, revealing gregarious larvae to be more likely to feed on a narrower range of host plant species than solitary larvae. We also find evidence that this increased specialisation typically precedes the evolutionary transition to gregarious behaviour. The comparatively greater host specialisation of gregarious larvae suggests that there are specific morphological and/or ecological features of their host plants that favour this behaviour.

Comparative metabolomic study of fungal foliar endophytes and their long-lived host Astrocaryum sciophilum: a model for exploring the chemodiversity of host-microbe interactions.

In contrast to the dynamics observed in plant/pathogen interactions, endophytic fungi have the capacity to establish enduring associations within their hosts, leading to the development of a mutually beneficial relationship that relies on specialized chemical interactions. Research indicates that the presence of endophytic fungi has the ability to significantly modify the chemical makeup of the host organism. Our hypothesis proposes the existence of a reciprocal exchange of chemical signals between plants and fungi, facilitated by specialized chemical processes that could potentially manifest within the tissues of the host. This research aimed to precisely quantify the portion of the cumulative fungal endophytic community's metabolome detectable within host leaves, and tentatively evaluate its relevance to the host-endophyte interplay. The understory palm Astrocaryum sciophilum (Miq.) Pulle was used as a interesting host plant because of its notable resilience and prolonged life cycle, in a tropical ecosystem. Using advanced metabolome characterization, including UHPLC-HRMS/MS and molecular networking, the study explored enriched metabolomes of both host leaves and 15 endophytic fungi. The intention was to capture a metabolomic "snapshot" of both host and endophytic community, to achieve a thorough and detailed analysis. This approach yielded an extended MS-based molecular network, integrating diverse metadata for identifying host- and endophyte-derived metabolites. The exploration of such data (>24000 features in positive ionization mode) enabled effective metabolome comparison, yielding insights into cultivable endophyte chemodiversity and occurrence of common metabolites between the holobiont and its fungal communities. Surprisingly, a minor subset of features overlapped between host leaf and fungal samples despite significant plant metabolome enrichment. This indicated that fungal metabolic signatures produced in vitro remain sparingly detectable in the leaf. Several classes of primary metabolites were possibly shared. Specific fungal metabolites and/or compounds of their chemical classes were only occasionally discernible in the leaf, highlighting endophytes partial contribution to the overall holobiont metabolome. To our knowledge, the metabolomic study of a plant host and its microbiome has rarely been performed in such a comprehensive manner. The general analytical strategy proposed in this paper seems well-adapted for any study in the field of microbial- or microbiome-related MS and can be applied to most host-microbe interactions.

Neofusicoccum parvum: A NOVEL PATHOGEN SPECIES CAUSING WILTED LEAF AND DIEBACK PETIOLES ON LOTUS (Nelumbo nucifera) IN THUA THIEN HUE, VIETNAM

Lotus (Nelumbo nucifera) is an essential species in many countries. In Vietnam, the lotus is a plant with cultural and spiritual significance, representing purity, spiritual growth, and enlightenment. However, petiole dieback and wilted dry leaves are severe diseases that weaken the host and decrease leaf photosynthesis, reducing lotus production. In this study, a new dieback and wilted leaf pathogen were identified via its morphology, phylogeny, and pathogenicity. Four representative Botryosphaeriaceae isolates from lotus fields in Hue, Phong Dien, and Phu Loc were selected for identification and pathogenicity testing. Based on morphological and phylogenetic analyses and by using the ribosomal internal transcribed spacer region (ITS) and β-tubulin (tub-2) gene sequences, we identified four isolates as Neofusicoccum parvum. In the pathogenicity test, typical symptoms appear on the inoculated lotus petioles, including dieback, curving, and wilted leaves. These symptoms are consistent with those observed in the field. In addition to identifying the pathogen species responsible for lotus disease, this study provides valuable insights into the taxonomy and phylogenetic relationships of new fungal pathogens that affect lotus fields. These findings can contribute to effective management strategies to control these diseases and improve lotus production. To the best of our knowledge, this is the first report of characterization and phylogenetic analysis of N. fusicoccum as the causal agent of wilted leaves and dieback disease in Thua Thien Hue, Vietnam.

The leaf-mining genus Lyonetia Hbner from China, with descriptions of two new species (Lepidoptera: Yponomeutoidea: Lyonetiidae).

So far, only five species of the genus Lyonetia Hbner, 1825 have been recorded in China. In this paper, we describe two new species: L. (Lyonetiola) blasta T. Liu, sp. n., and L. (Lyonetiola) duplistriata T. Liu, sp. n., and report a newly recorded species, L. (Lyonetia) ledi Wocke, 1859 from China. Autumnal forms, manifesting darker forewings, of L. (Lyonetia) clerkella (Linnaeus, 1758) were collected from Xizang at an altitude of 3650 m in summer. The distribution and host plants of L. (Lyonetia) clerkella (Linnaeus, 1758) and L. (Lyonetia) prunifoliella (Hbner, 1796) in China are summarized. Photos of adults, male and female genitalia are provided. Host plants, leaf mines and DNA barcodes are also provided when available.

Phenolic acids and defense-related enzymes in host-pathogen interaction in Senecio aegyptius and the rust fungus, Puccinia lagenophorae

The objective of this study was to investigate the effect of the rust fungus Puccinia lagenophorae on total phenols, phenolic acids, and defense-related enzymes in the leaf tissues of the host, Senecio aegyptius. The infection increased the total phenol and defense-related enzymes in the host leaf tissues when compared to healthy tissues. The analysis using HPLC revealed the existence of 10 phenolic acids in healthy and infected host leaves. The infection increased the amounts of caffeic, chlorogenic, ferulic, p-coumaric, and salicylic acids. The examination by TEM revealed the presence of peroxidase activity on the host microbodies, Golgi bodies, endoplasmic reticulum, and the thickening of xylem vessels. After the infection, the activity was localized at the penetration sites of fungal haustoria and in amorphous materials found between the intercellular hyphae and the host cell wall. The heaviest peroxidase activity was detected in heavily infected vascular tissue, due to the monokaryotic infection.

Visual acuity of Empoasca onukii (Hemiptera, Cicadellidae)

Empoasca onukii is a common tea plant pest with a preference for the color yellow. Past work has shown that host leaf color is a key cue for habitat location for E. onukii. Before studying the effect of foliage shape, size, or texture on habitat localization, it is necessary to determine the visual acuity and effective viewing distance of E. onukii. In this study, a combination of 3D microscopy and X-ray microtomography showed that visual acuity did not significantly differ between females and males, but there were significant differences in the visual acuity and optical sensitivity among five regions of E. onukii's compound eyes. The dorsal ommatidia had the highest visual acuity at 0.28 cycles per degree (cpd) but the lowest optical sensitivity (0.02 μm2sr), which indicated a trade-off between visual resolution and optical sensitivity for E. onukii. The visual acuity determined from the behavioral experiment was 0.14 cpd; E. onukii exhibited low-resolution vision and could only distinguish the units in a yellow/red pattern within 30 cm. Therefore, visual acuity contributes to the limited ability of E. onukii to distinguish the visual details of a distant target, which might be perceived as a lump of blurred color of intermediate brightness.

Phyllosphere antibiotic resistome in a natural primary vegetation across a successional sequence after glacier retreat

The spread of antibiotic-resistance genes (ARGs) has posed a significant threat to human health over the past decades. Despite the fact that the phyllosphere represents a crucial pool of microorganisms, little is known about the profile and drivers of ARGs in less human interference natural habitats. In order to minimize the influence of environmental factors, here we collected leaf samples from the early-, middle- and late-successional stages across a primary vegetation successional sequence within 2 km, to investigate how the phyllosphere ARGs develop in natural habitats. Phyllosphere ARGs were determined using high-throughput quantitative PCR. Bacterial community and leaf nutrient content were also measured to assess their contribution to the phyllosphere ARGs. A total of 151 unique ARGs were identified, covering almost all recognized major antibiotic classes. We further found that there was some stochastic and a core set of the phyllosphere ARGs during the plant community succession process, due to the fluctuant phyllosphere habitat and specific selection effect of plant individuals. The ARG abundance significantly decreased due to the reduction of the phyllosphere bacterial diversity, community complexity, and leaf nutrient content during the plant community succession process. While the closer links between soil and fallen leaf resulted in a higher ARG abundance in leaf litter than in fresh leaf. In summary, our study reveals that the phyllosphere harbors a broad spectrum of ARGs in the natural environment. These phyllosphere ARGs are driven by various environmental factors, including the plant community composition, host leaf properties, and the phyllosphere microbiome.

Influence of abiotic factors on kinetics of viable populations of biocontrol agents in the phyllosphere of lettuce and strawberry leaves

AbstractThere is little information on the effect of temperature, relative humidity (RH) and vapour pressure deficit (VPD) on the viable populations of two commercial biocontrol strains, Bacillus subtilis QST 713 (recently classified as B. velezensis) and Gliocladium catenulatum J1446 (syn. Clonostachys rosea). The PMAxx‐qPCR molecular assay was used to quantify the viable biocontrol agent (BCA) populations on fully extended lettuce and strawberry leaves under a range of temperature and RH combinations. Overall, there was a small decline in the population size of viable cells for the two biocontrol organisms on strawberry and lettuce leaves within 10 days of application. However, for most experimental runs, which contained general UK agronomy climates, such a decline was not statistically significant. Moreover, for a few runs, the viable populations increased significantly in optimal BCA growth temperatures with high RH. Only temperature (ambient) and dew point significantly affected the rate of temporal changes in the viable biocontrol population size. Thus, an increasing temperature led to decreased daily mortality. It should be noted that much of the variability in the estimated daily mortality rates remains unaccounted for, thus unless under extreme conditions, the biocontrol efficacy in practice is less likely to be affected by the survival of biocontrol microbes but more likely by other factors that influence the density of biocontrol cells in the phyllosphere, especially dilution due to rapid host leaf expansion, spray coverage and rain wash‐off.

Host range, damage extent and leaf consumptions by the bagworm, Thyridopteryx ephemeraeformis Haw. (Lepidoptera: Psychidae) in Bangladesh

Bagworm, Thyridopteryx ephemeraeformis Haw. (Lepidoptera: Psychidae) is a polyphagous pest in Northern America and southern Australia, causing severe damage to several host plants. A study was conducted to record the host plants, damage extent, and morphometrics of bagworms in Patuakhali Science and Technology University (PSTU) from 2015 to 2018. Results revealed a limited number of host plants for bagworm namely guava (Psidium guajava), arborvitae/juniper (Thuja standishii), rangan or jungles, geranium (Ixora grandiflora/Ixora coccinea), mussaenda (Mussaenda philippica), cropperleaf (Acalypha wilkesiana ‘Ceylon), henna (Lawsonia inermis), mango (Mangifera indica), pomegranate (Punica granatum) and betel nut (Areca catechu). The length of tiny larvae, fully-grown larvae, pupa, adult winged male moths, and wingless adult maggot-like females was 1.02 mm, 24.8 mm, 14 mm, 15 mm, and 48 mm, respectively. The average length of the bag was 24.7 mm with a range of 21-28 mm, and the average breadth in the middle of the bag was 6.9 mm with a range of 6-8 mm. The highest number of larval cases per branch was found in guava (56), and the lowest was in copperleaf (8). The highest percent of leaf damage (86.23%) per plant was also observed in the guava plant, and the lowest percent of leaf damage (37.46%) was in copperleaf. The highest number of infested leaves and bags per leaf was observed in the lower stratum of the guava branch, while the lowest infestation was in the top stratum. The highest percentage of leaf area (30%) damage was recorded 72 hours after release (HAR), and the lowest percentage of leaf area (10%) damage was at 24 HAR in guava. The maximum amount of leaf was consumed by bagworm larva at 72 HAR and the minimum amount was consumed at 24 HAR in guava. The maximum leaf area (13.46 cm2) consumption was recorded at 72 HAR, while the minimum amount (3.42 cm2) was consumed at 24 HAR. No significant damage by T. ephemeraeformis was observed in the case of mango, pomegranate, and betel nut plants. J. Asiat. Soc. Bangladesh, Sci. 48(1-2): 1-17, June-December 2022

Dynamics of cell wall components and histochemical profile of a rust fungi gall (Basidiomycota: Pucciniales) on Byrsonima variabilis A.Juss. (Malpighiaceae)

Context An obligate biotrophic parasitism with a rust fungus led to gall formation on Byrsonima variabilis. Aims The hypothesis that the host leaf–rust fungi interaction alters the dynamics of plant cell walls and the histochemical profile toward favouring the plant cell-to-fungi cell translocation of metabolites is tested. Methods Gall samples were sectioned and submitted to anatomical, histometric, histochemical, and immunocytochemical techniques to evaluate structural alterations and the detection of primary and secondary metabolites, as well as the epitopes of glycoproteins, pectins, and hemicelluloses. Key results Fungi gall development results in the hypertrophy of the stomatal chamber and the hyperplasia of epidermis and spongy parenchyma. The cell-to-cell translocation of metabolites from plant mesophyll cells toward the rust fungi gall is favoured by the epitopes of homogalacturonans (HGs) and (1 → 5) α-l-arabinans detected in the hyphae passage sites in the pycnial and aecial stages. The arabinogalactan-proteins (AGPs) may favour mycelial nutrition and differentiation, and cell wall adhesion. HGs and arabinans confer porosity to mesophyll cell walls, which favours the traffic of molecules toward the rust fungi gall. Conclusions The unexpected labelling of AGPs, HGs, and arabinans in fungi cell walls is a novelty regarding the plant–fungi interaction. The primary metabolites detected in rust fungi support hyphae growth and spore maturation. Implications The immunolabelling of host plant cell wall components on fungi cell walls indicates the integrative role of some plant cell wall components in the biological process of pathogen colonisation in leaf tissues.

Plant identity shapes phyllosphere microbiome structure and abundance of genes involved in nutrient cycling

The phyllosphere is a fluctuant micro-environment habitat that harbors diverse microbial communities that have the potential to influence plant growth through their effect on host fitness. However, we know little about the driving factors of phyllosphere microbial functional traits, e.g., genes related to nutrient cycling and microbial community structure under anthropic disturbance. Here, we characterized phyllosphere microbial communities and the abundance of genes related to nutrient cycling from diverse plant species between urban and natural habitats. We measured leaf functional traits to investigate the potential drivers of the phyllosphere microbial profile. Results indicated that phyllosphere microbial communities differed significantly between urban and natural habitats, and that this variation was dependent upon plant species. Host plant species had a greater influence on the abundance of genes involved in nutrient cycling in the phyllosphere than habitat. In addition, phyllosphere microbial diversity and functional gene abundance were significantly correlated. Furthermore, host leaf functional traits (e.g., specific leaf area and nutrient content) were potential driving factors of both phyllosphere microbial community structure and the abundance of genes involved in nutrient cycling. These findings contribute to a better understanding of the phyllosphere microbiome and its biotic and abiotic controlling factors, which improves our understanding of plant-microbe interactions and their ecosystem functions under anthropic disturbance.

Identification of effector CEP112 that promotes the infection of necrotrophic Alternaria solani

BackgroundAlternaria solani is a typical necrotrophic pathogen that can cause severe early blight on Solanaceae crops and cause ring disease on plant leaves. Phytopathogens produce secretory effectors that regulate the host immune response and promote pathogenic infection. Effector proteins, as specialized secretions of host-infecting pathogens, play important roles in disrupting host defense systems. At present, the role of the effector secreted by A. solani during infection remains unclear. We report the identification and characterization of AsCEP112, an effector required for A. solani virulence.ResultThe AsCEP112 gene was screened from the transcriptome and genome of A. solani on the basis of typical effector signatures. Fluorescence quantification and transient expression analysis showed that the expression level of AsCEP112 continued to increase during infection. The protein localized to the cell membrane of Nicotiana benthamiana and regulated senescence-related genes, resulting in the chlorosis of N. benthamiana and tomato leaves. Moreover, comparative analysis of AsCEP112 mutant obtained by homologous recombination with wild-type and revertant strains indicated that AsCEP112 gene played an active role in regulating melanin formation and penetration in the pathogen. Deletion of AsCEP112 also reduced the pathogenicity of HWC-168.ConclusionOur findings demonstrate that AsCEP112 was an important effector protein that targeted host cell membranes. AsCEP112 regulateed host senescence-related genes to control host leaf senescence and chlorosis, and contribute to pathogen virulence.

Different Gut Microbiomes of Developmental Stages of Field-Collected Native and Invasive Western Bean Cutworm, Striacosta albicosta, in Western Nebraska.

While insects harbor gut microbial associates that perform various functions for the host, lepidopterans have not been considered as prime examples of having such relationships. The western bean cutworm, Striacosta albicosta (Lepidoptera: Noctuidae), is native to North America and has historically been a significant corn pest in its western distribution. It is currently expanding eastwards and is invasive in these new regions. Using 16S rRNA gene sequencing data, this study focused on characterizing the microbiota associated with field-collected eggs, larvae, adults, and host plant materials of S. albicosta in its native range. The diversity of microbiomes varied significantly among S. albicosta eggs, larvae, adults, and the host plant materials. Microbial diversity was highest in adult stages relative to other insect stages. Furthermore, S. albicosta eggs, larvae, and adults harbored very distinct microbial communities, indicative of stage-specific microbiomes possibly performing different functions. Bacterial taxa underscoring these differences in composition identified four phyla and thirty families across samples. Members of the Firmicutes (Unassigned Lactobacillales), Proteobacteria (Pseudomonadaceae and Moraxellaceae), Bacteroidota (Weeksellaceae), and Chloroflexi dominated across all developmental stages. In addition, cellulose-degrading Lactobacillales (phylum: Firmicutes) dominated larval microbiomes, indicative of larval plant diet. This taxon was comparatively negligible in eggs and adults. Members of Proteobacteria dominated egg and host leaf microbiomes, while members of Bacteroidota dominated nectar-feeding adult gut microbiomes. Our results suggest a possible diet-dependent stage-specific microbiome composition and the potential for using stage-specific microbes as potential biological control tools against this important pest moving forward.

Bottom‐up effects of plant quantity and quality on arthropod diversity across multiple trophic levels in a semi‐arid grassland

Abstract Plant quantity and quality can independently affect the diversity of the entire arthropod communities and multiple arthropod taxa in grassland ecosystems. However, it remains unclear how these effects on arthropod taxa at one trophic level propagate through food web to influence the diversity of higher trophic levels. We performed a monoculture experiment with 15 herbaceous species in the Inner Mongolian grassland to investigate how natural variations in plant productivity and host leaf traits affect herbivore taxon richness, which, in turn, affects predator taxon richness. For herbivores, plant productivity indirectly promoted herbivore taxon richness by increasing herbivore biomass, which was attributed to the increases in the richness of dominant sucking herbivores and endophytes with high food requirements. However, the high plant quality indicator (e.g. high leaf protein, phosphorus and water contents, and high leaf protein to carbohydrate ratio) directly increased, whereas the low plant quality indicator (e.g. high leaf lignin content) directly decreased herbivore taxon richness. Taxon richness of chewing and sucking herbivores with specific feeding modes (tearing or sucking mouthparts) showed strong positive responses to increasing plant quality. For predators, herbivore taxon richness, rather than herbivore biomass, mainly mediated the positive effects of plant productivity and the high plant quality indicator, but the negative effect of the low plant quality indicator, on predator taxon richness. At the feeding guild level, the taxon richness of parasitoids, other predators and spiders exhibited positive responses to different herbivores, which was attributed to their different diet preferences. Predator diversity could be promoted by prey partitioning among predator guilds facilitating species coexistence. At the family level, the taxon richness of most predator families was positively correlated with that of more than one herbivore family, suggesting that high predator diversity may be caused by balanced diets owing to high prey diversity. Synthesis. Natural variations in plant quantity and quality can substantially affect the diversity of herbivores and cascade up the food web to affect predators. Specificity and mechanisms of feeding have a large impact on the responses of arthropod guilds at each trophic level.

A novel fossil-species of Meliolinites Selkirk (fossil Meliolaceae) and its life cycle stages associated with an angiosperm fossil leaf from the Siwalik (Mio-Pliocene) of Bhutan sub-Himalaya

Here, we report the in-situ occurrence of a new fossil-species of Meliolinites (fossil Meliolaceae), Meliolinites bhutanensis sp. nov. on the cuticle fragments of a compressed angiosperm dicot leaf recovered from the middle Siwalik (Formation II: latest Miocene to Pliocene) of Bhutan, eastern Himalaya. This unique foliicolous new fossil fungal species features well-preserved mycelia consisting of superficial, brown to dark brown, septate, thick-walled, branching hyphae with bi-cellular appressoria, unicellular phialides, and a characteristic long, slightly curved hyphal seta. The web-like, brown to dark brown fungal colonies also include globose to sub-globose, dark brown ascomata, and oblong to broadly cylindrical, 5-celled, 4-septate, brown to dark brown, mature ascospores. As almost all features of different stages in the life cycle (ascospores, mature germinating ascospores, superficial lateral hyphae, hyphal seta, hyphopodia, mycelial colony, and ascomata) of this new fossil-species are found, we have proposed the first time a possible life cycle of fossil-species of Meliolaceae. The in-situ evidence of M. bhutanensis on the host leaf cuticle indicates the possible existence of a host-ectoparasite relationship in Bhutan sub-Himalaya's ancient warm and humid tropical evergreen forest during the deposition. So, M. bhutanensis might have thrived generally under warm and humid climate conditions for its growth and development in the Mio-Pliocene time, which is in conformity with our recently published quantitative climatic data by CLAMP (Climate Leaf Analysis Multivariate Program) analysis.