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Both Metarhizium robertsii ARSEF 2575 (Mr2575) and Metarhizium anisopliae ARSEF 549 (Ma549) infect a range of insects whilst also interacting with plants; however, little is known about the traits that affect the competitive ability of different strains. We examined the interactions between Mr2575 and Ma549 in culture and during co-infection of plants (Arabidopsis thaliana) and insects. Mr2575 outcompetes Ma549 under nutrient-limiting conditions, including root exudates, giving it a priority advantage on Arabidopsis roots. However, during co-infection of Manduca sexta or Drosophila melanogaster, Ma549's higher blastospore production enhanced its competitive ability within the host. In large M. sexta (fifth instar), blastospores facilitate dispersal, suppress host melanization and prevent Mr2575 from spreading from infection sites, reducing conidia production. However, colonization of smaller hosts such as first instar M. sexta and D. melanogaster did not provide Ma549 with a competitive advantage, as conidial production was dependent on retaining control of the cuticle through which conidiating hyphae emerge. Unexpectedly, Ma549 and Mr2575 segregate within hosts, suggesting resource partitioning with Mr2575 predominating in the thoraxes of Drosophila, especially in females, and Ma549 in the abdomen. In fifth instar M. sexta, Mr2575 was most prevalent around spiracles and the front end of segments, despite Ma549 and Mr2575 having similar susceptibility to hypoxia. Dispersing conidia homogeneously into the hemocoel of fifth instar M. sexta eliminated the blastospore production advantage, making Ma549 and Mr2575 equally competitive, with strict partitioning of Mr2575 at the anterior and Ma549 at the posterior ends of segments. As Metarhizium species have multiple roles in natural ecosystems and agroecosystems these discoveries are relevant to understanding their impact on maintaining biodiversity and for exploiting them to enhance food security. Author summary: Metarhizium spp. are keystone fungi providing essential ecosystem services as plant symbionts and insect pathogens, yet little is known about how different strains interact. We analyzed two strains with different insect-killing strategies: Mr2575 kills insects with toxins before colonizing cadavers, whereas Ma549 rapidly colonizes living insects. Ma549's rapid growth within insects serves as a strong anti-competitive strategy in larger insects. However, in smaller insects, Mr2575 remains competitive in reproductive potential (spore production on cadavers) if it maintains control of the cuticle through which it entered the insect. Consequently, small hosts may be more critical than large hosts for preserving pathogen diversity. Unexpectedly, Mr2575 and Ma549 partition insect hosts between them, promoting coexistence. We also investigated trade-offs between virulence traits and plant colonization traits, finding that Mr2575's rapid growth in sparse nutrients enhances its competitiveness on plant roots. Thus, Mr2575 may be more competitive on plants, while Ma549 excels in large insects, with both strains showing similar competitiveness in small insects. These insights are important for understanding Metarhizium species' roles in biodiversity and their potential to boost food security in natural and agricultural ecosystems. [ABSTRACT FROM AUTHOR]

Biotic disturbances caused by insects and pathogens have a major impact on forests in the Northern Hemisphere. Knowledge of the effects of increasing temperature on the performance of these forest pests will thus be crucial for predicting future disturbance risks. Here, we systematically review the direct effects of increasing temperatures on four functional subgroups of forest pests, including leaf chewers, sap suckers, bark and wood borers, and pathogens. We considered 118 studies (2003–2022) representing 72 pest species feeding on 33 host genera from sub‐tropical, temperate and boreal forests in Asia, Europe and North America. Based on a subset of 89 studies reporting the required data, we conducted a meta‐analysis 1) distinguishing the functional subgroups, and 2) considering the main life‐history traits, i.e. development, fitness and survival. A temperature corresponding to the expected mean temperature during the growing season in the years 2081–2100 had a significant positive effect on the overall performance of leaf chewers (+18%) and bark and wood borers (+10%), while sap suckers and pathogens remained unaffected. In contrast, performance was not or even significantly negatively affected when a more pronounced temperature increase, i.e. corresponding to the temperature maxima in 2081–2100, was considered. This finding reflects the non‐linear temperature–performance relationship beyond currently evolved temperature optima in insects and pathogens. Furthermore, we showed that differential responses of life‐history traits to increased temperatures may counterbalance each other (e.g. development versus survival), highlighting the importance of a multi‐trait approach to assessing the impact of global warming on pest performance. By quantifying the effects of increasing temperatures on forest pest performance, our results facilitate the prediction of biotic disturbance impacts in a future climate. For instance, they could provide a valuable contribution to the parameterization of large‐scale ecosystem models, which often do not explicitly consider the response of biotic disturbances to climate change. [ABSTRACT FROM AUTHOR]

Summit disease, in which infected hosts seek heights (gravitropism), first noted in modern times by nineteenth-century naturalists, has been shown to be induced by disparate pathogens ranging from viruses to fungi. Infection results in dramatic changes in normal activity patterns, and such parasite manipulation of host behaviors suggests a strong selection for convergent outcomes albeit evolved via widely divergent mechanisms. The two best-studied examples involve a subset of viral and fungal pathogens of insects that induce "summiting" in infected hosts. Summiting presumably functions as a means for increasing the dispersal of the pathogen, thus significantly increasing fitness. Here, we review current advances in our understanding of viral- and fungal-induced summit disease and the host behavioral manipulation involved. Viral genes implicated in this process include a host hormone-targeting ecdysteroid UDP-glucosyltransferase (apparently essential for mediating summit disease induced by some viruses but not all) and a protein tyrosine phosphatase, with light dependance implicated. For summit disease-causing fungi, though much remains obscure, targeting of molting, circadian rhythms, sleep, and responses to light patterns appear involved. Targeting of host neuronal pathways by summit-inducing fungi also appears to involve the production of effector molecules and secondary metabolites that affect host muscular, immune, and/or neurological processes. It is hypothesized that host brain structures, particularly Mushroom Bodies (no relation to the fungus itself), important for olfactory association learning and control of locomotor activity, are critical targets for mediating summiting during infection. This phenomenon expands the diversity of microbial pathogen-interactions and host dynamics. Key points: • Summit disease or height seeking (gravitropism) results from viral and fungal pathogens manipulating insect host behaviors presumably to increase pathogen dispersal. • Insect baculoviruses and select fungal pathogens exhibit convergent evolution in host behavioral manipulation but use disparate molecular mechanisms. • Targets for affecting host behavior include manipulation of host hormones, feeding, locomotion, and immune, circadian, and neurological pathways. [ABSTRACT FROM AUTHOR]

Indole-3-carbinol (I3C), a hydrolysis product of indole-3-methylglucosinolate, is toxic to herbivorous insects and pathogens. In mammals, I3C is extensively studied for its properties in cancer prevention and treatment. Produced in Brassicaceae, I3C reversibly inhibits root elongation in a concentration-dependent manner. This inhibition is partially explained by the antagonistic action of I3C on auxin signaling through TIR1. To further elucidate the mode of action of I3C in plants, we have employed a forward-genetic amiRNA screen that circumvents functional redundancy. We identified and characterized two amiRNA lines with impaired I3C response. The first line, ICT2, targets the phosphatidylinositol 4-phosphate 5-kinase family (PIP5K), exhibiting tolerance to I3C, while the second line, ICS1, targets the Wall-Associated Kinases (WAK1–3) family, showing susceptibility to I3C. Both lines maintain I3C-induced antagonism of auxin signaling, indicating that their phenotypes are due to auxin-independent mechanisms. Transcript profiling experiments reveal that both lines are transcriptionally primed to respond to I3C treatment. Physiological, metabolomic, and transcriptomic analysis reveal that these kinases mediate numerous developmental processes and are involved in abiotic and biotic stress responses. [ABSTRACT FROM AUTHOR]

The first step in trait introgression is to identify and assess novel sources of variation. For shrub willow (Salix) breeders, there is an abundance of understudied species within a genus that readily hybridizes. Breeding targets in shrub willow center on traits contributing to biomass yield for bioenergy. These include stem biomass, insect and pathogen resistance, and leaf architecture traits. More specifically, breeding for durable resistance to willow leaf rust (Melampsora spp.) is of particular importance as the pathogen can significantly reduce biomass yields in commercial production. The Salix F1 hybrid common parent population (Salix F1 HCP) was created to characterize the variation among eight species‐hybrid families and map QTL for targeted traits. A female and male S. purpurea were used as common parents in crosses made to male S. suchowensis, S. viminalis, S. koriyanagi, and S. udensis and female S. viminalis, S. integra, S. suchowensis to produce eight families that were planted in field trials at Cornell AgriTech in Geneva, NY and phenotyped. Using 16 previously described parental backcross linkage maps and two newly generated S. purpurea consensus maps, we identified 215 QTL across all eight families and in every parent. These included 15 leaf rust severity, 61 herbivory, 65 leaf architecture, and 74 yield component QTL, resulting in 50 unique overlapping regions within the population. These genetic loci serve as an important foundation for future shrub willow breeding, and each interspecific family was identified as a novel source of useful alleles for trait introgression into high yielding cultivars. [ABSTRACT FROM AUTHOR]

• Aquaculture sludge represents a promising future feed material for insects. • BSF larvae can grow on a substrate solely composed of aquaculture sludge. • BSF larvae reduced aquaculture waste and accumulated valuable nutrients. • BSF larvae accumulated undesirable substances including Cd, Hg and dioxins. Aquaculture sludge (uneaten feed and faeces) is nutrient rich and has potential as feed for insects. The aim of this study was to investigate the transfer of chemical and biological contaminants, as well as nutrients, from aquaculture sludge to black soldier fly larvae. The larvae were reared on a sludge mixture made of different sludges collected from Norwegian freshwater salmonid facilities. The sludge was spiked with four common salmon pathogens: Infectious Pancreatic Necrosis Virus, Infectious Salmon Anemia virus, Yersinia ruckeri or Mycobacterium salmoniphilum. During the 15 days of growth on sludge, the black soldier fly larvae accumulated valuable nutrients including protein, fat, eicosapentaenoic acid, iron, manganese, zinc and selenium. The larvae also accumulated undesirable substances including cadmium, mercury, dioxins and polychlorinated biphenyls. The concentrations of dioxins exceeded the EU maximum level set for animal feed. None of the salmon pathogens that were spiked to the sludge were detected in the black soldier fly larvae. This study reports low risk of transfer of salmon pathogens from sludge to insect larvae, and showed that the transfer of heavy metals, minerals and metalloids are in accordance with earlier studies. The large variations in levels of heavy metals between batches of sludge can cause levels in BSF exceeding the EU maximum levels, and thus indicate a need for monitoring of the proposed value chain. The transfer of dioxins from sludge to insects, reported for the first time in this paper, would be of special interest for future research, with special focus on risk mitigation. [ABSTRACT FROM AUTHOR]

Background: Photorhabdus asymbiotica is a species of the insect pathogenic Photorhabdus genus that has been isolated as an etiological agent in human infections. Since then, multiple isolates have been identified worldwide; however, actual clinical infections have so far only been identified in North America, Australia, and Nepal. Previous research on the clinical isolates had shown that the strains differed in their behaviour when infecting cultured human cells. Methods: In this study, we investigate the differences between the pathogenic activities of P. asymbiotica isolates from different geographic locations. Pathogenicity was analysed using infection assays with both cultured cell lines (THP-1, CHO, and HEK cells) and primary immune cells, and peripheral blood mononuclear cells (PBMCs) isolated from human blood. Results: Here, we present the findings from the Australian (Kingscliff) and North American (ATCC43949) clinical isolates, and non-clinical soilborne nematode isolates from Thailand (PB68) and Northern Europe (HIT and JUN) of P. asymbiotica. We also show the first findings from a new clinical isolate of P. luminescens (Texas), the first non-asymbiotica species to cause a human infection, confirming its ability to infect and survive inside human immune cells. Conclusion: Here for the first time, we show how P. asymbiotica selectively infects certain immune cells while avoiding others and that infectivity varies depending on growth temperature. We also show that the tropism varies depending on the geographic location a strain is isolated from, with only the European HIT and JUN strains lack the ability to survive within mammalian cells in tissue culture. [ABSTRACT FROM AUTHOR]

Strawberry is frequently attacked by mites, which directly affects the yield and quality of this fruit species. The WRKY Group III transcription factors (TFs) play an important role in plant tolerance to biotic sources of stress, such as pathogens and insect pests. In this study, six Group III WRKY TFs (FaWRKY25, FaWRKY31, FaWRKY32, FaWRKY43, FaWRKY44, and FaWRKY45) were identified in strawberry. A phylogenetic analysis showed that the six WRKY III TFs were divided into two clades and all had a conserved WRKYGQK domain and the C-X7-C-X23-H-T-C zinc finger motif. An interaction network analysis revealed that FaWRKY44 was co-expressing with FaWRKY25 and FaWRKY45. The expression patterns showed that the WRKY Group III genes responded to plant hormones and mite infestation in strawberry. To further verify the role of FaWRKY25 in plant resistance to mites, we cloned the FaWRKY25 gene and overexpressed it in transgenic plants. An in vivo subcellular localization analysis indicated that the FaWRKY25 protein was localized in the nucleus. Fewer mites were also detected on the wild-type plants than on FaWRKY25-overexpressing transgenic plants, suggesting that FaWRKY25 negatively regulates the resistance of strawberry to mites. The present study advances our understanding on a potential target that mites use to manipulate host plant defenses. [ABSTRACT FROM AUTHOR]

The study used some biological control components and evaluated them against the two-spotted mite Tetranychius urticae Koch. on eggplant and pepper crops in the spring season in Salah al-Din Government, Iraq. The laboratory study included a compatibility study between the biopesticide Vertimec and the two fungi Metarhizium and Beauveria, as well as alcoholic and aqueous oleander leaf extracts. The results were positive and caused an increase in the colony area of the two fungi at concentrations below the recommended levels; the Beauveria fungus is activated by the aqueous extract of the oleander plant at a rate of 0.5 ml/l. The colony area was 29.5 cm², while the colony area for comparison was 24.64 cm². The sub-mixtures recommended from the compatibility results were adopted to combat eggplant and pepper fields infected with economically essential pests. The compatibility between the biopesticide Vertimec and two biopesticides, Metarism and Beauveria, showed the highest killing value, as it gave the eggplant plants treated with (Metarism+Vertimec pesticide) at a concentration of 1 ml/1 ml for the two periods after one and three days. Tthe highest corrected percentage for killing, it reached (92.33 and, 96.77) mites. As for pepper plants, the combination between (Metarrhizm+Vertemic pesticide) succeeded in sub-lethal rates (ml/1 ml/liter), which after three days were subjected to the highest kill rates of (100) % of mites. The study's findings are an effective way to combat this pest and the field of integrated management to combat it and implement sustainable agriculture using environmentally friendly pesticides. [ABSTRACT FROM AUTHOR]

Cicer arietinum (chickpea) is an annual herbaceous crop and the world's third most important food legume, belonging to the genus Cicer. Chickpea is rich in carbohydrates, proteins and bioactive compounds. A variety of climatic and environmental conditions influence chickpea growth, development and grain yield. Its significance and utilization for several health diseases have been cited in ancient manuscripts and the Ayurvedic system of medicine. Determining the origin and dispersal routes of this plant has been one of the most interesting issues among botanists. This review gives an outline of the available literature on morphological characteristics, origin, habitat features, nutritional compositionand medicinal uses of the chickpea. Chickpea is cultivated in a wide variety of agroecological conditions worldwide, especially in arid and semi-arid climates. It is susceptible to soil type, soil pH, waterlogging, temperature (drought and cold), annual rainfall, salinity, high boron, insect and pathogen attacks, herbicidesand weeds, especially broad-leafed weeds. Chickpea originated in the Mediterranean/Fertile Crescent from Cicer reticulatum through mutants and spread to Central Asia and likely in parallel from Central Asia to South Asia (India) and East Africa (Ethiopia). It is a chief source of sustainable, inexpensive protein, also abundant in complex carbohydrates, fatty acids, isoflavones, vitamins, minerals and dietary fiber. Cicer arietinum possesses several medicinally significant activities such as antimicrobial, antioxidant, anti-inflammatory, anti-hypercholesterolemia, anti-hepatotoxicity, anti-hyperglycemia, anti-cancer and nephrolithiasis. [ABSTRACT FROM AUTHOR]

A dynamic homeostasis between gut microbiome and the host is essential for animals. Antibiotics feeding may be a good way to study the function of microbes in insects due to efficiency and a linkage with pest control. Here, by using 16S rDNA sequencing, we show antibiotics feeding significantly altered the composition and diversity of microbes in different stages of Spodoptera frugiperda and showed dose dependent effects. Antibiotics ingestion resulted in a dramatic reduction of Enterococcus in larvae and Klebsiella in adults, but increase of Weissella in larvae and Pseudomonas in pupae and adults. Enterococcus spp in the lepidopteran gut may play a protective role against insect pathogens and Klebsiella spp may have positive effects on insect fecundity. Some strains from Pseudomonas and Weissella are pathogens or opportunistic pathogens. Further biological assay showed that antibiotics treatment significantly affected the fitness of treated insects and their untreated offspring, with treated insects and their offspring having longer developmental period but lower body weight, survival rate, flight capacity and fecundity than those of controls. Lepidopterans may rely on gut microbiome for some digestions and previous study indicated that antibiotics-induced dysbiosis of gut microbes affects many biological processes of S. frugiperda. Therefore, it is possible that antibiotics disrupted the homeostasis of gut microbes and the host, which then negatively affected the survival and reproduction of S. frugiperda. These findings contribute to a better understanding of the role of the microbiota in insects and will aid in the development of environmentally friendly management techniques for this pest. [ABSTRACT FROM AUTHOR]

• Sequential induction by fungal pathogen and insect elicits differential biochemical responses. • Necrotrophic fungal attack decreases the nutritional quality of the plant. • Late-arriving herbivore is negatively affected by the presence of pathogen, with or without herbivore's presence. • Herbivory did not affect the late-arriving conspecific herbivore. Plants have several means of coping with biotic stress, which involves physiological, cellular and molecular mechanisms. The interplay of two principal phytohormonal pathways, Jasmonic acid (JA) and Salicylic acid (SA) play a crucial role in transmitting stress-induced signals throughout the plant. However, the interplay of these hormonal pathways is not clear when plants encounter biotic agents that trigger antagonistic hormonal signals. To address this, we conducted biochemical and gene expression studies on tomato, Solanum lycopersicum plants, exposed to insect alone (IA), fungus alone (FA), or sequential dual stress with fungi followed by insect (FI) and insect followed by fungi (IF), with untreated control. We also assessed the performance of late-arriving conspecific herbivore on these plant sets. The total phenol, and non-tannin phenols content in IF and FI plants showed similar increase or decrease as FA and IA plants, respectively. Gene expression analysis revealed that JA-related genes (MYC2) were dominant in FI plants, while SA-related genes (PR1) were upregulated in IF plants. Moreover, late-arriving herbivores showed significantly decreased relative growth rate, efficiency of conversion of ingested food (ECI) and digested food (ECD) when feeding on FA and IF plants, indicating that sequential treatments substantially induce plant responses. However, herbivory did not affect the late-arriving conspecific herbivore. Thus, biochemical responses and hormonal interplay of the plant are influenced by both sequence as well as the duration of the biotic stress. Furthermore, while the late-arriving conspecific herbivore is negatively affected by the presence of a pathogen, it remains unaffected by previous herbivory. [ABSTRACT FROM AUTHOR]

Despite major breeding efforts by various national and international agencies, yields for the ~40 million hectares of maize, the major food crop in sub‐Saharan Africa, have stagnated at <2 tons/ha/year for the past decade, one‐third the global average. Breeders have succeeded in breeding increased yield with a modicum of tolerance to some single‐weed or pathogen stresses. There has been minimal adoption of these varieties because introgressing polygenic yield and tolerance traits into locally adapted material is very challenging. Multiple traits to deal with pests (weeds, pathogens, and insects) are needed for farmer acceptance, because African fields typically encounter multiple pest constraints. Also, maize has no inherent resistance to some of these pest constraints, rendering them intractable to traditional breeding. The proposed solution is to simultaneously engineer multiple traits into one genetic locus. The dominantly inherited multi‐pest resistance trait single locus can be bred simply into locally adapted, elite high‐yielding material, and would be valuable for farmers, vastly increasing maize yields, and allowing for more than regional maize sufficiency. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: β‐N‐acetylhexosaminidases (HEXs) are widely distributed in fungi and involved in cell wall chitin metabolism and utilization of chitin‐containing substrates. However, details of the fungal pathogens‐derived HEXs in the interaction with their hosts remain limited. RESULTS: An insect nutrients‐induced β‐N‐acetylhexosaminidase, BbHex1, was identified from the entomopathogenic fungus Beauveria bassiana, which was involved in cell wall modification and degradation of insect cuticle. BbHex1 was localized to cell wall and secreted, and displayed enzyme activity to degrade the chitinase‐hydrolyzed product (GlcNAc)2. Disruption of BbHex1 resulted in a significant decrease in the level of cell wall chitin in the presence of insect nutrients and during infection of insects, with impaired ability to penetrate insect cuticle, accompanying downregulated cell wall metabolism‐involved and cuticle‐degrading chitinase genes. However, the opposite phenotypes were examined in the gene overexpression strain. Distinctly altered cell wall structures caused by BbHex1 mutation and overexpression led to the easy activation and evasion (respectively) of insect immune response during fungal infection. As a result, BbHex1 contributed to fungal virulence. Bioinformatics analysis revealed that promoters of some co‐expressed chitinase genes with the BbHex1 promoter shared conserved transcription factors Skn7, Msn2 and Ste12, and CreA‐binding motifs, implying co‐regulation of those genes with BbHex1. CONCLUSION: These data support a mechanism that the fungal pathogen specifically expresses BbHex1, which is co‐expressed with chitinases to modify cell wall for evasion of insect immune recognition and to degrade insect cuticle, and contributes to the fungal virulence against insects. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), is a significant insect pest with global veterinary implications due to its capacity to both cause nuisance and transmit disease‐causing pathogens to livestock. This study aimed to determine the livestock bedding preferred for use as a development substrate by S. calcitrans larvae and field‐collected adults. The result showed that S. calcitrans larvae exhibited a preference (26.7%) for 7‐day‐old cow manure. Gravid females displayed a pronounced preference (55.0%) for fresh cow manure. As there were eight choices, indifference would result in 12.5% for each bedding substrate. Furthermore, the efficacy of four entomopathogenic nematodes (EPNs), namely Heterorhabditis bacteriophora (Poinar), Heterorhabditis indica Poinar, Karunakar & David (Rhabditida: Heterorhabditidae), Steinernema siamkayai Poinar, Karunakar & David and Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), against S. calcitrans larvae and the persistence after application to livestock bedding substrates were evaluated under laboratory conditions. In filter paper bioassays, all four EPNs caused 76.7%–100.0% mortality in the second instar larvae of S. calcitrans when applied at 50 and 100 infective juveniles (IJs)/cm2 within 5 days after exposure. For the third instar larvae of S. calcitrans, only H. indica induced high mortalities of 86.6% when applied at 100 IJs/cm2 within 5 days after exposure, while the other EPNs resulted in mortalities of less than 70%. The data further demonstrated that H. bacteriophora, H. indica and S. siamkayai remained present in the substrates linked to S. calcitrans larvae for as long as 7 days after the application of EPNs. This study demonstrates the potential of EPNs as a biologically based control agent against larvae of S. calcitrans, a serious pest and significant vector for various livestock animals. [ABSTRACT FROM AUTHOR]

Plants have evolved diverse defense mechanisms encompassing physical and chemical barriers. Cotton pigment glands are known for containing various defense metabolites, but the precise regulation of gland size to modulate defense compound levels remains enigmatic. Here, it is discovered that the VQ domain‐containing protein JAVL negatively regulates pigment gland size and the biosynthesis of defense compounds, while the MYC2‐like transcription factor GoPGF has the opposite effect. Notably, GoPGF directly activates the expression of JAVL, whereas JAVL suppresses GoPGF transcription, establishing a negative feedback loop that maintains the expression homeostasis between GoPGF and JAVL. Furthermore, it is observed that JAVL negatively regulates jasmonate levels by inhibiting the expression of jasmonate biosynthetic genes and interacting with GoPGF to attenuate its activation effects, thereby maintaining homeostatic regulation of jasmonate levels. The increased expression ratio of GoPGF to JAVL leads to enlarged pigment glands and elevated jasmonates and defense compounds, enhancing insect and pathogen resistance in cotton. These findings unveil a new mechanism for regulating gland size and secondary metabolites biosynthesis, providing innovative strategies for strengthening plant defense. [ABSTRACT FROM AUTHOR]

Insects are established models for understanding host-pathogen interactions and innate immune mechanisms. The innate immune system in insects is highly efficient in recognizing and opposing pathogens that cause detrimental effects during infection. The cuticular layer which covers the superficial layer of the insect body participates in host defense and wound healing by inducing innate immune responses. Previous studies have started to address the involvement of cuticular genes in conferring resistance to insect pathogens, particularly those that infect by disrupting the insect cuticle. For example, the cuticular gene Transglutaminase (TG) in Drosophila melanogaster plays a structural role in cuticle formation and blood coagulation and also possesses immune properties against pathogenic infection. However, more information is becoming available about the immune function of other cuticular gene families in insects. In this review, we aim to highlight the recent advances in insect cuticular immunity and address the necessity of pursuing further research to fill the existing gaps in this important field of insect immunology. This information will lead to novel strategies for the efficient management of agricultural insect pests and vectors of plant and human disease. [ABSTRACT FROM AUTHOR]

BACKGROUND: Citrus huanglongbing (HLB) is a devastating disease caused by Candidatus Liberibacter asiaticus (CLas) that affects the citrus industry. In nature, CLas relies primarily on Diaphorina citri Kuwayama as its vector for dissemination. After D. citri ingests CLas‐infected citrus, the pathogen infiltrates the insect's body, where it thrives, reproduces, and exerts regulatory control over the growth and metabolism of D. citri. Previous studies have shown that CLas alters the composition of proteins in the saliva of D. citri, but the functions of these proteins remain largely unknown. RESULTS: In this study, we detected two proteins (DcitSGP1 and DcitSGP3) with high expression levels in CLas‐infected D. citri. Quantitative PCR and Western blotting analysis showed that the two proteins were highly expressed in the salivary glands and delivered into the host plant during feeding. Silencing the two genes significantly decreased the survival rate for D. citri, reduced phloem nutrition sucking and promoted jasmonic acid (JA) defenses in citrus. By contrast, after overexpressing the two genes in citrus, the expression levels of JA pathway‐associated genes decreased. CONCLUSION: Our results suggest that CLas can indirectly suppress the defenses of citrus and support feeding by D. citri via increasing the levels of effectors in the insect's saliva. This discovery facilitates further research into the interaction between insect vectors and pathogens. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Sentinel gardens are effective in assessing the risk of insect or pathogen invasions on plants from offshore regions. Limited knowledge exists on wood borers' potential impact on expatriate plants and host stress levels. We surveyed wood borers colonizing 11 North American tree species planted in two sentinel gardens in China, recording 38 species from 9 families, mainly Curculionidae (Scolytinae), Cerambycidae, and Cossidae. Quercus texana was the most attacked host. Wood borers typically infest unhealthy or dead tissues, regardless of overall tree vitality. We identified species capable of colonizing healthy trees: Anoplophora chinensis (Forster) (Cerambycidae), Sinoxylon sp. (Bostrichidae), and Polyphagozerra coffeae (Nietner) (Cossidae). Several insects colonizing stressed trees included: Xylosandrus crassiusculus (Motschulsky), Xyleborus affinis (Eichhoff), Xylosandrus germanus (Blandford) (all Curculionidae-Scolytinae), and Chlorophorus sp. (Cerambycidae). Some, such as A. chinensis and P. coffeae, are under-documented but potentially invasive pests with considerable regulatory importance. Most recorded species are already recognized as pest of live trees or invasive elsewhere, indicating a limited number of potentially invasive wood borers rather than an inexhaustible pool. This suggests that sentinel gardens are effective for pest prevention prioritization. We recommend three methodological improvements for pre-invasion assessments: 1) documenting the vitality of specific colonized tissues to avoid misrepresenting secondary colonizers as primary pests, 2) using fully digital data-management from tree planting to insect identification, and 3) routinely identifying pests using DNA. [ABSTRACT FROM AUTHOR]

Agricultural productivity is frequently threatened by a range of insect pests and pathogens that cause damage to crops. The use of chemical insecticides for control has raised concerns due to negative environmental effects, potential risks to animal and human health, and the emergence of insecticide resistance. Such issues pose threats to the future crop generations. To address these challenges, the application of biological control agents, particularly fungal insect pathogens, has shown promise in effectively managing crop pests and disease vectors. In recent years, significant progress has been made in harnessing the potential of entomopathogenic fungi (EF) for insect pest management. These advancements encompass the discovery and characterization of new fungal isolates, a better understanding their ecological effects in plants, integration of fungal agents within Integrated Pest Management (IPM) strategies, and improvements in their efficacy, formulation, and range of applications. Efforts to overcome limitations in the use of EF under natural conditions and for large-scale applications have also yielded substantial advancements. Here, we provide an overview of recent successes achieved using EF as biocontrol agents, while also addressing their continued limitations, identifying promising areas for further research and challenges associated with utilizing EF. Progress in enhancing the safety and effectiveness of biocontrol methods using EF has led to important breakthroughs. These advancements have the potential to improve food security and safety while reducing adverse environmental impacts associated with pests. [ABSTRACT FROM AUTHOR]

To date, several synthetic preservatives have been used for management of food losses caused by insect and fungal pathogens, however, development of resistant races and adverse effects on environment have limited their applicability. Currently, essential oils and their bioactive components are well acknowledged for control of insects. Insecticidal and antifungal efficacy of essential oils are reported to result from neurotoxic mechanisms like alteration in octopamine receptors, γ-aminobutyric acid (GABA) ion channels, inhibition of acetylcholine esterase (AChE) activities in insects and dysfunctioning of mitochondria as well as plasma membrane in fungal pathogens. Nanoencapsulation of essential oils is currently under practice to prevent environmental degradation, enhance insecticidal and fungicidal efficacy with wide commercial applications and recommend them for possible industrial utilization. The present review explores i) insecticidal and fungicidal efficacy of essential oils and bioactive components, ii) their possible mode of action, iii) the employment of modern nanoencapsulation approaches for the development of nontoxic and ecofriendly green insecticides/fungicides, and most importantly iv) patenting of developed plant based nanoformulation with desired application in management of stored products biodeterioration. [ABSTRACT FROM AUTHOR]

In the course of our ongoing research targeting the identification of potential biocontrol agents from entomopathogenic fungi (EPF), we explored a solid-state rice fungal extract of Blackwellomyces roseostromatus BCC56290 derived from infected lepidopteran larvae. Chemical and biological prospections afforded four unprecedentedly reported natural products differentiated into a dimeric naphthopyran bioxanthracene ES-242 derivative (1) and three cyclodepsipeptides (2–4) in addition to two known cyclodepsipeptides, cardinalisamides B (5) and C (6). Chemical structures of the isolated compounds were elucidated through comprehensive 1D/2D NMR and HR-ESI-MS data together with comparisons to the reported literature. The absolute configuration of the isolated cyclodepsipeptides was determined using Marfey's method. All isolated compounds were assessed for their antimicrobial, cytotoxic, and nematicidal activities with some compounds revealing significant activities. [ABSTRACT FROM AUTHOR]

Background: The fall armyworm (FAW), Spodoptera frugiperda (J.E. Nixon) (Lepidoptera: Noctuidae), is the major insect pest that infests cereal crops recently in African and Asian countries. The insect is polyphagous that attacks large numbers of host plants, especially maize and rice, causing considerable losses in their annual yield. The integrated pest management (IPM) of the insect depended mainly on insecticides and to some extent on biological control agents including insect pathogens (nematodes, fungi, bacteria and viruses). Results: Different species of entomopathogens (nematodes, fungi, viruses and bacteria) infecting the insect could be isolated in such newly invaded countries. Laboratory and field experiments indicated that the insect was found to be susceptible to the isolated entomopathogens, and thus, they could be promising biocontrol agents against this insect. Conclusion: This review article proved the susceptibility of S. frugiperda to the most of tested entomopathogens. However, more field studies have to be carried out in order to include such entomopathogens within integrated pest management programs against this insect pest. [ABSTRACT FROM AUTHOR]

The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama is the leading vector of Candidatus Liberibacter asiaticus (CLas), the causative agent of citrus Huanglongbing (HLB) disease. The distribution and dynamics of CLas within ACP are critical to understanding how the transmission, spread and infection of CLas occurs within its host vector in nature. In this study, the distribution and titer changes of CLas in various tissues of ACP 5th instar nymphs and adults were examined by fluorescence in situ hybridization (FISH) and real-time quantitative PCR (qPCR) techniques. Results demonstrated that 100% of ACP 5th instar nymphs and adults were infected with CLas following feeding on infected plants, and that CLas had widespread distribution in most of the tissues of ACP. The titers of CLas within the midgut, salivary glands and hemolymph tissues were the highest in both 5th instar nymphs and adults. When compared with adults, the titers of CLas in these three tissues of 5th instar nymphs were significantly higher, while in the mycetome, ovary and testes they were significantly lower than those of adults. FISH visualization further confirmed these findings. Dynamic analysis of CLas demonstrated that it was present across all the developmental ages of ACP adults. There was a discernible upward trend in the presence of CLas with advancing age in most tissues of ACP adults, including the midgut, hemolymph, salivary glands, foot, head, cuticula and muscle. Our findings have significant implications for the comprehensive understanding of the transmission, dissemination and infestation of CLas, which is of much importance for developing novel strategies to halt the spread of CLas, and therefore contribute to the efficient prevention and control of HLB. [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi (EPFs) are a significant group of insect pathogens that are used as microbial insecticides with distinct physiological mechanisms of pathogenicity. During our survey in the middle of March 2020 to early October 2022 on natural EPF as a biological control agent of the longhorn beetle (LHB) Osphranteria coerulescens, new isolates of EPFs were found on LHB larvae in apple orchards of Dargaz, Razavi Khorasan province, Iran. The nBLAST results of this these indigenous isolate indicated the highest similarity to Cladosporium sp. (Ascomycota: Davidiellaceae) with ON307222.1 access number and for EF-1α indicated the highest similarity to Cladosporium sp. with MH724951.1 access number. To assess the virulence of these indigenous isolates of EPF, a series of tests were conducted on the LHB larvae stages. Conidial concentrations 104, 105, 106, 107, and 108 (conidia/ml− 1) caused (10.21 ± 2.1), (23.44 ± 2.4), (28.72 ± 2.6), (33.23 ± 3.1) and (34.02 ± 2.8) % of mortality in LHB, respectively and there was no significant difference between 108 and 107 (conidia/ml−1) concentrations. The mortality results by the time showed that the process did not start until 3 days after treatment, and after that, it sped up. This research gathers new information about cryptic inhabiting larvae which shows considerable potential for this Cladosporium species to be implemented within the microbial control program of the LHB. This research is a new report isolating the pathogenicity of Cladosporium sp. on LHB. These fungal isolates have considerable potential for the microbiological control of the LHB. [ABSTRACT FROM AUTHOR]

Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are central components of the machinery mediating cell membrane fusion and intracellular vesicular trafficking in eukaryotic cells, and have been well-documented to play critical roles in growth, development, and pathogenesis in the filamentous fungal plant pathogens. However, little is known about the contributions of SNAREs to the physiology and biocontrol potential in entomopathogenic filamentous fungi. Here, a genome-wide analysis of SNARE genes was performed taking advantage of the available whole genome sequence of Beauveria bassiana, a classical entomopathogenic fungus. Based on the compared genomic method, 22 genes encoding putative SNAREs were identified from the whole genome of B. bassiana, and were classified into four groups (7 Qa-, 4 Qb-, 6 Qc-, and 5 R-SNAREs) according to the conserved structural features of their encoding proteins. An R-SNARE encoding gene BbSEC22 was further functionally characterized by gene disruption and complementation. The BbSEC22 null mutant showed a fluffy appearance in mycelial growth and an obvious lag in conidial germination. The null mutant also exhibited significantly increased sensitivity to oxidative stress and cell wall perturbing agents and reduced the yield of conidia production by 43.1% compared with the wild-type strain. Moreover, disruption of BbSEC22 caused a significant decrease in conidial virulence to Spodoptera litura larvae. Overall, our results provide an overview of vesicle trafficking in B. bassiana and revealed that BbSec22 was a multifunctional protein associated with mycelial growth, sporulation, conidial germination, stress tolerance, and insecticidal virulence. [ABSTRACT FROM AUTHOR]

Estimating parameters for multiple datasets can be time consuming, especially when the number of datasets is large. One solution is to sample from multiple datasets simultaneously using Bayesian methods such as adaptive multiple importance sampling (AMIS). Here, we use the AMIS approach to fit a von Mises distribution to multiple datasets for wind trajectories derived from a Lagrangian Particle Dispersion Model driven from 3D meteorological data. A posterior distribution of parameters can help to characterise the uncertainties in wind trajectories in a form that can be used as inputs for predictive models of wind-dispersed insect pests and the pathogens of agricultural crops for use in evaluating risk and in planning mitigation actions. The novelty of our study is in testing the performance of the method on a very large number of datasets (>11,000). Our results show that AMIS can significantly improve the efficiency of parameter inference for multiple datasets. [ABSTRACT FROM AUTHOR]

Introduction: The white-spotted flower chafer (Protaetia brevitarsis seulensis), which is widely distributed in Asian countries, is traditionally used in oriental medicine. However, its larvae are prone to severe damage by green muscardine disease (caused by Metarhizium anisopliae) during breeding. The aim of this study was to characterize Bacillus velezensis TJS119, which has been isolated from freshwater, and investigate its potential as a biocontrol agent against M. anisopliae in insects. Methods: TJS119 was obtained from freshwater samples in the Republic of Korea and was classified as B. velezensis. We evaluated its in vitro antifungal effect, sequenced the bacterial whole genome, mined genes responsible for the synthesis of secondary metabolites, performed secondary metabolite analysis Ultra performance liquid chromatography-mass spectrometry (UPLC-MS/MS), and conducted bioassays for determining green muscardine disease control ability. Results: Bacillus velezensis TJS119 inhibited the mycelial growth of M. anisopliae in vitro. The size of the B. velezensis TJS119 genome was estimated to be 3,890,913 bp with a GC content of 46.67% and 3,750 coding sequences. Biosynthetic gene clusters for secondary metabolites with antifungal activity were identified in the genome. Lipopeptides, including fengycin secreted by TJS119 exhibit antifungal activity. Application of TJS119 for the biocontrol against green muscardine disease increased the viability of white-spotted flower chafer by 94.7% compared to the control. Discussion: These results indicate that B. velezensis TJS119 is a potential biocontrol agent for insect pathogens. [ABSTRACT FROM AUTHOR]

Food crops are attacked by microbial pathogens and insect pests, leading to significant yield reductions and economic losses. Conventional disease diagnosis and management approaches often fail to provide rapid and eco-friendly solutions. In the current situation, nanomaterials (NMs) serve a valuable role in both managing emerging pathogens and monitoring overall plant health. Nanotechnology has transformed the biotechnology industry including agriculture with specific applications such as nano-fungicides, nano-bactericides, and nano-pesticides. This review focuses on the use of various nanomaterials, including inorganic materials such as Ag, ZnO, CuO, and CeO, as well as carbon-based nanoparticles, nanotubes, nanowires, and nano-capsules. The application of NMs holds the potential to address various challenges in food security through novel applications like advanced nano-biosensors for rapid pathogen detection and targeted disease management strategies. This includes the potential to minimize reliance on chemical inputs and contribute to more sustainable agricultural practices. Nanomaterials (NMs) promise to deliver plant hormones and signaling molecules to plants, enhancing resistance inducers against major crop pathogens. NMs against newly arising pathogens through reactive oxygen generation, membrane damage, and biochemical interference are also reviewed. However, challenges regarding the stability, toxicity, and environmental impacts of NMs are discussed, along with recommendations on green synthesis and functionalization approaches. This article aims to investigate the role of nanomaterials (NMs) in managing emerging pathogens and monitoring overall crop health offering an insightful outlook for future generations. Further biosafety aspects and larger-scale validation of NM-based applications could enable their commercialization for improving global food security. [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi play a significant role in regulating insect populations in nature and have potential applications in pest management strategies in different regions. Citrus spp. are among the important horticultural products in northern Iran, and the orchards are affected by different insect pests, especially mealybugs. This study aimed to isolate and identify entomopathogenic fungi associated with citrus orchard pests in northern Iran, focusing on Akanthomyces and Lecanicillium species on mealybugs. Through the samples collected from different regions within Guilan province, 12 fungal isolates were collected and identified based on the combination of morphological characteristics and molecular data. Akanthomyces lecanii, A. muscarius, Engyodontium rectidentatum, Lecanicillium aphanocladii and Lecanicillium rasoulzarei sp. nov. were identified. Of these, A. muscarius on Lepidosaphes sp., E. rectidentatum on Coccidae, and L. aphanocladii on Tetranychus urticae are reported as new fungal-host records from Iran. Moreover, a new species, Lecanicillium rasoulzarei, is illustrated, described, and compared with closely related species. [ABSTRACT FROM AUTHOR]

Phenolamides are important secondary metabolites in plant species. They play important roles in plant defense responses against pathogens and insect herbivores, protection against UV irradiation and floral induction and development. However, the accumulation and variation in phenolamides content in diverse maize lines and the genes responsible for their biosynthesis remain largely unknown. Here, we combined genetic mapping, protein regulatory network and bioinformatics analysis to further enhance the understanding of maize phenolamides biosynthesis. Sixteen phenolamides were identified in multiple populations, and they were all significantly correlated with one or several of 19 phenotypic traits. By linkage mapping, 58, 58, 39 and 67 QTLs, with an average of 3.9, 3.6, 3.6 and 4.2 QTLs for each trait were mapped in BBE1, BBE2, ZYE1 and ZYE2, explaining 9.47%, 10.78%, 9.51% and 11.40% phenotypic variation for each QTL on average, respectively. By GWAS, 39 and 36 significant loci were detected in two different environments, 3.3 and 2.8 loci for each trait, explaining 10.00% and 9.97% phenotypic variation for each locus on average, respectively. Totally, 58 unique candidate genes were identified, 31% of them encoding enzymes involved in amine and derivative metabolic processes. Gene Ontology term analysis of the 358 protein-protein interrelated genes revealed significant enrichment in terms relating to cellular nitrogen metabolism, amine metabolism. GRMZM2G066142, GRMZM2G066049, GRMZM2G165390 and GRMZM2G159587 were further validated involvement in phenolamides biosynthesis. Our results provide insights into the genetic basis of phenolamides biosynthesis in maize kernels, understanding phenolamides biosynthesis and its nutritional content and ability to withstand biotic and abiotic stress. [ABSTRACT FROM AUTHOR]

The corn leafhopper, Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae) is the vector of the Corn stunt disease, caused by a complex of pathogens, a serious threat to corn production in tropical and subtropical regions of the American continent. The aim of this study was to conduct an exploratory analysis to estimate the structure and genetic differentiation of D. maidis populations from three geographical regions collected during two maize growing seasons in northwestern Argentina using inter -simple sequence repeats (ISSR) markers. Populations in the High -elevation Valley and Dry Plain sites, despite being geographically separated by mountains of high elevations, were genetically similar, while the nearest populations located in Dry Plain and Humid Piedmont were the most genetically different. The results suggested that populations of D. maidis in subtropical maize-growing areas are structured according to the climatic conditions, mainly humidity and precipitation. Additionally, this structure might be influenced by annual migrants from northern tropical areas, as well as by individuals that occasionally survive from one season to the next as occurs in the Humid Piedmont. Darker body coloration of females sampled during the second year in Dry Plain and Humid Piedmont might be associated with colder temperatures during the winter before maize cultivation. This study is the first conducted in Argentina on the genetic div ersity of populations of D. maidis. The results presented here highlight the need for further investigation into the origin and potential movement of D. maidis populations. Knowing how the crop is colonized will aid in the development of well - fitting models, for preventing the disease caused by the pathogens transmitted by this insect. [ABSTRACT FROM AUTHOR]

Summary: Maize is one of the most important crops for food, cattle feed and energy production. However, maize is frequently attacked by various pathogens and pests, which pose a significant threat to maize yield and quality. Identification of quantitative trait loci and genes for resistance to pests will provide the basis for resistance breeding in maize. Here, a β‐glucosidase ZmBGLU17 was identified as a resistance gene against Pythium aphanidermatum, one of the causal agents of corn stalk rot, by genome‐wide association analysis. Genetic analysis showed that both structural variations at the promoter and a single nucleotide polymorphism at the fifth intron distinguish the two ZmBGLU17 alleles. The causative polymorphism near the GT‐AG splice site activates cryptic alternative splicing and intron retention of ZmBGLU17 mRNA, leading to the downregulation of functional ZmBGLU17 transcripts. ZmBGLU17 localizes in both the extracellular matrix and vacuole and contribute to the accumulation of two defence metabolites lignin and DIMBOA. Silencing of ZmBGLU17 reduces maize resistance against P. aphanidermatum, while overexpression significantly enhances resistance of maize against both the oomycete pathogen P. aphanidermatum and the Asian corn borer Ostrinia furnacalis. Notably, ZmBGLU17 overexpression lines exhibited normal growth and yield phenotype in the field. Taken together, our findings reveal that the apoplastic and vacuolar localized ZmBGLU17 confers resistance to both pathogens and insect pests in maize without a yield penalty, by fine‐tuning the accumulation of lignin and DIMBOA. [ABSTRACT FROM AUTHOR]

Pathogens play a key role in insect population dynamics, contributing to short‐term fluctuations in abundance as well as long‐term demographic trends. Two key factors that influence the effects of entomopathogens on herbivorous insect populations are modes of pathogen transmission and larval host plants. In this study, we examined tritrophic interactions between a sequestering specialist lepidopteran, Euphydryas phaeton, and a viral pathogen, Junonia coenia densovirus, on its native host plant, Chelone glabra, and a novel host plant, Plantago lanceolata, to explore whether host plant mediates viral transmission, survival, and viral loads. A two‐factor factorial experiment was conducted in the laboratory with natal larval clusters randomly assigned to either the native or novel host plant and crossed with either uninoculated controls or viral inoculation (20% of individuals in the cluster inoculated). Diapausing clusters were overwintered in the laboratory and checked weekly for mortality. At the end of diapause, all surviving individuals were reared to adulthood to estimate survivorship. All individuals were screened to quantify viral loads, and estimate horizontal transmission postmortem. To test for vertical transmission, adults were mated, and the progeny were screened for viral presence. Within virus‐treated groups, we found evidence for both horizontal and vertical transmission. Larval clusters reared on the native host plant had slightly higher horizontal transmission. Survival probability was lower in clusters feeding on the native host plant, with inoculated groups reared on the native host plant experiencing complete mortality. Viral loads did not differ by the host plant, although viral loads decreased with increased sequestration of secondary compounds on both host plants. Our results indicate that the use of a novel host plant may confer fitness benefits in terms of survival and reduced viral transmission when larvae feeding on it are infected with this pathogen, supporting hypotheses of potential evolutionary advantages of a host range expansion in the context of tritrophic interactions. [ABSTRACT FROM AUTHOR]

Entire chromosomes are typically only transmitted vertically from one generation to the next. The horizontal transfer of such chromosomes has long been considered improbable, yet gained recent support in several pathogenic fungi where it may affect the fitness or host specificity. To date, it is unknown how these transfers occur, how common they are, and whether they can occur between different species. In this study, we show multiple independent instances of horizontal transfers of the same accessory chromosome between two distinct strains of the asexual entomopathogenic fungus Metarhizium robertsii during experimental co-infection of its insect host, the Argentine ant. Notably, only the one chromosome--but no other--was transferred from the donor to the recipient strain. The recipient strain, now harboring the accessory chromosome, exhibited a competitive advantage under certain host conditions. By phylogenetic analysis, we further demonstrate that the same accessory chromosome was horizontally transferred in a natural environment between M. robertsii and another congeneric insect pathogen, Metarhizium guizhouense. Hence, horizontal chromosome transfer is not limited to the observed frequent events within species during experimental infections but also occurs naturally across species. The accessory chromosome that was transferred contains genes that may be involved in its preferential horizontal transfer or support its establishment. These genes encode putative histones and histone-modifying enzymes, as well as putative virulence factors. Our study reveals that both intra- and interspecies horizontal transfer of entire chromosomes is more frequent than previously assumed, likely representing a not uncommon mechanism for gene exchange. [ABSTRACT FROM AUTHOR]

Serratia marcescens is a global opportunistic pathogen. In vitro cytotoxicity of this bacterium is mainly related to metalloprotease serralysin (PrtS) activity. Proteolytic capability varies among the different isolates. Here, we characterized protease production and transcriptional regulators at 37°C of two S. marcescens isolates from bronchial expectorations, HU1848 and SmUNAM836. As a reference strain the insect pathogen S. marcescens Db10 was included. Zymography of supernatant cultures revealed a single (SmUNAM836) or double proteolytic zones (HU1848 and Db10). Mass spectrometry confirmed the identity of PrtS and the serralysin-like protease SlpB from supernatant samples. Elevated proteolytic activity and prtS expression were evidenced in the HU1848 strain through azocasein degradation and qRT-PCR, respectively. Evaluation of transcriptional regulators revealed higher eepR expression in HU1848, whereas cpxR and hexS transcriptional levels were similar between studied strains. Higher eepR expression in HU1848 was further confirmed through an in vivo transcriptional assay. Moreover, two putative CpxR binding motifs were identified within the eepR regulatory region. EMSA validated the interaction of CpxR with both motifs. The evaluation of eepR transcription in a cpxR deletion strain indicated that CpxR negatively regulates eepR. Sequence conservation suggests that regulation of eepR by CpxR is common along S. marcescens species. Overall, our data incorporates CpxR to the complex regulatory mechanisms governing eepR expression and associates the increased proteolytic activity of the HU1848 strain with higher eepR transcription. Based on the global impact of EepR in secondary metabolites production, our work contributes to understanding virulence factors variances across S. marcescens isolates. [ABSTRACT FROM AUTHOR]

This overview initially describes insect immune reactions and then brings together present knowledge of the interactions of vector insects with their invading parasites and pathogens. It is a way of introducing this Special Issue with subsequent papers presenting the latest details of these interactions in each particular group of vectors. Hopefully, this paper will fill a void in the literature since brief descriptions of vector immunity have now been brought together in one publication and could form a starting point for those interested and new to this important area. Descriptions are given on the immune reactions of mosquitoes, blackflies, sandflies, tsetse flies, lice, fleas and triatomine bugs. Cellular and humoral defences are described separately but emphasis is made on the co-operation of these processes in the completed immune response. The paper also emphasises the need for great care in extracting haemocytes for subsequent study as appreciation of their fragile nature is often overlooked with the non-sterile media, smearing techniques and excessive centrifugation sometimes used. The potential vital role of eicosanoids in the instigation of many of the immune reactions described is also discussed. Finally, the priming of the immune system, mainly in mosquitoes, is considered and one possible mechanism is presented. [ABSTRACT FROM AUTHOR]

Introduction: Asian citrus psyllid (ACP, Diaphorina citri) is an important transmission vector of "Candidatus Liberibacter asiaticus" (CLas), the causal agent of Huanglongbing (HLB), the most destructive citrus disease in the world. As there are currently no HLB-resistant rootstocks or varieties, the control of ACP is an important way to prevent HLB. Some viruses of insect vectors can be used as genetically engineered materials to control insect vectors. Methods: To gain knowledge on viruses in ACP in China, the prevalence of five RNA and DNA viruses was successfully determined by optimizing reverse transcription polymerase chain reaction (RT-PCR) in individual adult ACPs. The five ACPassociated viruses were identified as follows: diaphorina citri bunyavirus 2, which was newly identified by high-throughput sequencing in our lab, diaphorina citri reovirus (DcRV), diaphorina citri picorna-like virus (DcPLV), diaphorina citri bunyavirus (DcBV), and diaphorina citri densovirus-like virus (DcDV). Results: DcPLV was the most prevalent and widespread ACP-associated virus, followed by DcBV, and it was detected in more than 50% of all samples tested. DcPLV was also demonstrated to propagate vertically and found more in salivary glands among different tissues. Approximately 60% of all adult insect samples were co-infected with more than one insect pathogen, including the five ACPassociated viruses and CLas. Discussion: This is the first time these viruses, including the newly identified ACPassociated virus, have been detected in individual adult ACPs from natural populations in China's five major citrus-producing provinces. These results provide valuable information about the prevalence of ACP-associated viruses in China, some of which have the potential to be used as biocontrol agents. In addition, analysis of the change in prevalence of pathogens in a single insect vector is the basis for understanding the interactions between CLas, ACP, and insect viruses. [ABSTRACT FROM AUTHOR]

We report observations of Onnia subtriquetra on bishop pine (Pinus muricata) and shore pine (Pinus contorta var. contorta) from north coastal California. Our identification of this fungus is supported by molecular information, morphological characteristics, and and a description of the observed range of the fungus on the West Coast. These observations represent an expansion of the geographic and host ranges of Onnia subtriquetra, which on the observed sites is generally associated with declining tree condition and the presence of other native forest pathogens and insects. [ABSTRACT FROM AUTHOR]

Plant enemies can indirectly affect pollinators by modifying plant traits, but simultaneous tests of herbivore and pathogen effects are lacking, and the role of floral volatiles has seldom been assessed.In this study, we tested for indirect effects of insect herbivores and pathogens on pollinator attraction via altered floral volatile emissions, and its consequences for plant fitness in Brassica rapa. Plants in the field were exposed to either no damage or damage by caterpillars (Mamestra brassicae), aphids (Brevicoryne brassicae), a leaf fungus (Sclerotinia sclerotiorum), or a bacterium (Xanthomonas campestris pv. campestris). We then recorded pollinator visits and measured floral traits (flower number, volatiles) and plant fitness‐correlates. We additionally performed a greenhouse experiment with artificial floral emitters to test for effects of target volatiles on pollinator attraction.In the field experiments, relative to controls, plants subjected to herbivory by the aphid B. brassicae (but not those exposed to the other enemies) exhibited a marked reduction in the emission of two volatile organic compounds (nonanal and 2‐butyl‐1‐octanol), experienced lower pollinator visits and produced seeds of lower quality in terms of seed biomass and germination rate, while flower output itself was not affected. Consistently, artificial emitters with reduced amounts of these volatile organic compounds were less attractive to pollinators under greenhouse conditions.Synthesis. These results provide strong evidence for volatile‐mediated indirect interactions between plant enemies and pollinators ultimately impacting plant fitness, and further point at enemy and compound specificity in such effects. [ABSTRACT FROM AUTHOR]

Simple Summary: Psyllids are insects that represent a potential threat to the cultivation of several crops, mainly as vectors of the 'Candidatus Liberibacter' bacteria species. Surveys on the presence and abundance of insect vectors of pathogens can provide important information on the presence of related pathogens in a certain area, even before the appearance of disease symptoms in plants. The occurrence of psyllid vectors was investigated on carrot crops in the "Altopiano del Fucino" area (Abruzzo region), where the highest Italian carrot production occurs. This survey revealed, for the first time in Italy, the presence of psyllid Bactericera trigonica adults associated with 'Candidatus Liberibacter solanacearum' (Lso). This finding provided important evidence of the risks for Lso outbreaks and prompted further research to assess the spread and the incidence of the bacterium in crop cultivations in Italy. Psyllids, members of the family Triozidae, represent a potential threat to the cultivation of solanaceous and apiaceous crops worldwide, mainly as vectors of the phloem-restricted bacterium 'Candidatus Liberibacter solanacearum' (Lso). The Lso haplotypes C, D and E are known to affect apiaceous crops, such as carrot and celery, in several European countries. In Italy, data on the incidence and natural spread of both Lso and psyllids have not been reported so far. In this study, the presence of the vectors was investigated in a main Italian district for carrot production, the "Altopiano del Fucino" area (Central Italy). Both occasional and regular surveys were carried out on a total of five carrot fields and one potato field in 2021 and 2022. Bactericera trigonica (Hodkinson), which is known to efficiently transmit Lso to carrots, was found to be well-established in the area. High levels of population density were recorded in the summer period (more than 100 adult specimens per trap caught every two weeks) and then sharply decreased after the carrot harvest, confirming the strict association of this psyllid species with crop availability. In 2022, 27.5% of the total tested psyllid samples resulted in being positive for Lso haplotypes D and E, the latter being prevalent. This survey revealed, for the first time in Italy, the presence of B. trigonica adults associated with Lso in carrot crops. Although this study was limited to a few fields located in one area, it provided important evidence of the risks for Lso outbreaks and prompted further research to assess the spread and incidence of the disease in apiaceous cultivations in Italy. [ABSTRACT FROM AUTHOR]

The brown planthopper (BPH), Nilaparvata lugens (Stål), a rice-specific pest, has risen to the top of the list of significant pathogens and insects in recent years. Host plant-mediated resistance is an efficient strategy for BPH control. Nonetheless, BPH resistance in rice cultivars has succumbed to the emergence of distinct virulent BPH populations. Circular RNAs (circRNAs) play a pivotal role in regulating plant–environment interactions; however, the mechanisms underlying their insect-resistant functions remain largely unexplored. In this study, we conducted an extensive genome-wide analysis using high-throughput sequencing to explore the response of rice circRNAs to BPH infestations. We identified a total of 186 circRNAs in IR56 rice across two distinct virulence groups: IR-IR56-BPH (referring to IR rice infested by IR56-BPH) and IR-TN1-BPH, along with a control group (IR-CK) without BPH infestation. Among them, 39 circRNAs were upregulated, and 43 circRNAs were downregulated in the comparison between IR-IR56-BPH and IR-CK. Furthermore, in comparison with IR-CK, 42 circRNAs exhibited upregulation in IR-TN1-BPH, while 42 circRNAs showed downregulation. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that the targets of differentially expressed circRNAs were considerably enriched in a multitude of biological processes closely linked to the response to BPH infestations. Furthermore, we assessed a total of 20 randomly selected circRNAs along with their corresponding expression levels. Moreover, we validated the regulatory impact of circRNAs on miRNAs and mRNAs. These findings have led us to construct a conceptual model that circRNA is associated with the defense regulatory network in rice, which is likely facilitated by the mediation of their parental genes and competing endogenous RNA (ceRNA) networks. This model contributes to the understanding of several extensively studied processes in rice-BPH interactions. [ABSTRACT FROM AUTHOR]

Plants play an important role in interactions between insect herbivores and their pathogens. The ability of host plants to modify the infectivity of entomopathogens in herbivorous insects has been widely documented. However, the plants' nutrients have always been neglected as a factor contributing to variation in the susceptibility of insect herbivores to entomopathogens. The fall-webworm (FWW), Hyphantria cunea Drury, is a typical polyphagous caterpillar, and the Hyphantria cunea nucleopolyhedrovirus (HycuNPV) is a distinctly specialized baculovirus for the FWW, which is safe for other organisms and has been effectively used as a biological insecticide against H. cunea in China. In this study, we investigated the nutrient components of four host plant species, i.e., Prunus serrulate, Cerasus serrulate, Camptotheca acuminata, and Populus deltoides, and their effects on the susceptibility of H. cunea larvae to HycuNPV. The HycuNPV-infected larvae fed on P. deltoides leaves exhibited higher survival rates, longer survival times, more food intake, and gained larger body size. These biological parameters were positively correlated with the nitrogen components of host plant leaves. Moreover, the larval antioxidant enzymes exhibited different responses to HycuNPV. HycuNPV infection significantly triggered the catalase (CAT) and prophenoloxidase (PPO) enzyme activity levels of H. cunea larvae. The uninfected larvae fed on poplar leaves induced a robust increase in the POD activity, which could scavenge extra reactive oxygen species and provide a protective effect against the HycuNPV. In conclusion, the plant-mediated effects of HycuNPV on the FWW have been investigated in this study. The nitrogen content in dietary was an essential factor in determining the insect herbivore susceptibility to entomopathogenic viruses, and it helped explain variations in the susceptibility of pests to the entomopathogenic viruses and aid in developing more robust tolerance monitoring assays in the lab that reflect the performance of pests in the field. [ABSTRACT FROM AUTHOR]

Insects constitute approximately 75% of the world's recognized fauna, with the majority of species considered as pests. Entomopathogenic fungi (EPF) are parasitic microorganisms capable of efficiently infecting insects, rendering them potent biopesticides. In response to infections, insects have evolved diverse defense mechanisms, prompting EPF to develop a variety of strategies to overcome or circumvent host defenses. While the interaction mechanisms between EPF and insects is well established, recent findings underscore that their interplay is more intricate than previously thought, especially evident across different stages of EPF infection. This review primarily focuses on the interplay between EPF and the insect defense strategies, centered around three infection stages: (1) Early infection stage: involving the pre-contact detection and avoidance behavior of EPF in insects, along with the induction of behavioral responses upon contact with the host cuticle; (2) Penetration and intrahemolymph growth stage: involving the initiation of intricate cellular and humoral immune functions in insects, while symbiotic microbes can further contribute to host resistance; (3) Host insect's death stage: involving the ultimate confrontation between pathogens and insects. Infected insects strive to separate themselves from the healthy population, while pathogens rely on the infected insects to spread to new hosts. Also, we discuss a novel pest management strategy underlying the cooperation between EPF infection and disturbing the insect immune system. By enhancing our understanding of the intricate interplay between EPF and the insect, this review provides novel perspectives for EPFmediated pest management and developing effective fungal insecticides. [ABSTRACT FROM AUTHOR]

Tea is the second most popular nonalcoholic beverage consumed in the world, made from the buds and young leaves of the tea plants (Camellia sinensis). Tea trees, perennial evergreen plants, contain abundant specialized metabolites and suffer from severe herbivore and pathogen attacks in nature. Thus, there has been considerable attention focusing on investigating the precise function of specialized metabolites in plant resistance against pests and diseases. In this review, firstly, the responses of specialized metabolites (including phytohormones, volatile compounds, flavonoids, caffeine, and L-theanine) to different attacks by pests and pathogens were compared. Secondly, research progress on the defensive functions and action modes of specialized metabolites, along with the intrinsic molecular mechanisms in tea plants, was summarized. Finally, the critical questions about specialized metabolites were proposed for better future research on phytohormone-dependent biosynthesis, the characteristics of defense responses to different stresses, and molecular mechanisms. This review provides an update on the biological functions of specialized metabolites of tea plants in defense against two pests and two pathogens. [ABSTRACT FROM AUTHOR]

Citrus is an economically important fruit crop in Pakistan; however, its productivity is affected by various insect pests and pathogens. Spores of Penicillium italicum Warmer are airborne and cause citrus blue mold disease in citrus plants. The main objective of this study was to assess the in-vitro efficacy of different concentrations of selected fungicides against P. italicum applied at different times. Before pouring, potato dextrose agar was made and modified with fungicides. For each concentration, three plates were poured. After the plates had solidified, a 5 mm mycelial plug of the fungus P. italicum was inserted in the center Five fungicides i.e., Nativo, Topsin-M, Metalaxyl+Mancozeb, Copper Oxychloride, Success were tested at three concentrations i.e., 100 ppm, 200 ppm, and 300 ppm. The findings of the study showed that Nativo was the best fungicide as the inhibition rate of P. italicum was 81.0-87.0%, after 7 days of application. The second most effective fungicide was Success, which showed 77.5-81.0% inhibition of P. italicum after 3 days and 78.0-80.0% after 7 days of application. Similarly, Topsin M showed 68.3-77.0% inhibition of P. italicum on 3 days and 77.0-81.0% on 7 days of application. Metalaxyl+Mancozeb and copper did not prove effective against P. italicum, even at higher concentrations. The higher concentration of each fungicide resulted in maximum inhibition of P. italicum. Thus, the current study suggests that Nativo, Success, and Topsin M could manage the citrus blue mold disease at the standardized concentration. [ABSTRACT FROM AUTHOR]

Cassava is an agricultural crop widely cultivated throughout Brazil, from north to south. However, this is due to the fact that it is a crop exploited, for the most part, by the segment of small producers, currently known as family farmers. However, phytosanitary problems can compromise the productivity of this crop. Therefore, due to the relevance of the subject and the importance of cassava farming for the State of Amapá, this work aims to investigate the perception of cassava producers in settlements in the municipality of Amapá regarding the main diseases and pests that affect cassava farming in crops. The work carried out in the two settlements (Piquiá and Cruzeiro) located in the municipality of Amapá. Interviews were carried out with producers using a questionnaire with questions about cassava farmers' perception of diseases and pests that affect cassava cultivation. The plant health data showed that cassava farmers reported the presence of pests and diseases that affect the crop, such as root rot, shoot fly and thread burning, but they did not practice the main strategies to prevent the proliferation of pathogens and insects. [ABSTRACT FROM AUTHOR]

Fungi in the genus of Tolypocladium are often discovered as endophytes, soil inhabitants, and insect pathogens. Many biologically active secondary metabolites have been discovered from them in the past half-century, including medicinally important oligopeptide cyclosporine A, and other compounds like terpenes, polyketides, polyketide-non-ribosomal peptides. This review has summarized the chemistry and pharmacology of natural products discovered from Tolypocladium genus fungi, to provide a full record of all Tolypocladium secondary metabolites. [ABSTRACT FROM AUTHOR]

Microbial biopesticides to control plant pathogens and insects in crops have had significant success. However, there have been relatively few successes for microbial bioherbicides in crops, despite considerable numbers of publications and commercial product introductions in this area. Marketed microbial bioherbicide products for use in agriculture have been largely unsuccessful. This article covers the potential advantages of successful microbial bioherbicides, as well as the biological and technical issues that have limited their success. Technologies to overcome the problems that have limited the success of these products are discussed. The many advantages of using killed microbial products (e.g. cell‐free filtrates) over living microbial products as bioherbicides are detailed. A commercialized mycoherbicide that has been selected for in the laboratory for control of the parasitic weed Striga hermonthica is being used with some success in Africa, indicating that non‐transgenic modification of the genetics of bioherbicide microbes for improved efficacy is acceptable to some regulatory authorities. Genetic modifications to improve efficacy and host range, as well as improved application technology to greatly reduce the amount of product needed are two technologies that are likely to expand the use of microbial bioherbicides in the future. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The North has experienced unprecedented rates of warming over the past few decades, impacting the survival and development of insects and the pathogens that they carry. Since 2019, Arctic foxes from Canada (Nunavut) have been observed with fur loss inconsistent with natural shedding of fur. Adult lice were collected from Arctic foxes from Nunavut (n = 1) and Svalbard (n = 2; Norway) and were identified as sucking lice (suborder Anoplura). Using conventional PCR targeting the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), lice from Canada and Svalbard were 100% similar (8 pooled samples from Nunavut and 3 pooled samples from Svalbard), indicating that there is potential gene flow between ectoparasites on Scandinavian and North American Arctic fox populations. The cox1 sequences of Arctic fox lice and dog sucking lice (Linognathus setosus) had significant differences (87% identity), suggesting that foxes may harbour a cryptic species that has not previously been recognised. Conventional PCR targeting the gltA gene for Bartonella bacteria amplified DNA from an unknown gammaproteobacteria from two pooled louse samples collected from Svalbard foxes. The amplified sequences were 100% identical to each other but were only 78% like Proteus mirabilis reported in GenBank (CP053614), suggesting that lice on Arctic foxes may carry unique microorganisms that have yet to be described. [ABSTRACT FROM AUTHOR]