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Tariq M. Butt - One of the best experts on this subject based on the ideXlab platform.
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Telomere length de novo assembly of all 7 chromosomes and mitogenome sequencing of the model entomopathogenic fungus, Metarhizium brunneum, by means of a novel assembly pipeline.
BMC genomics, 2021Co-Authors: Zack Saud, Alexandra M. Kortsinoglou, Vassili N. Kouvelis, Tariq M. ButtAbstract:BACKGROUND More accurate and complete reference genomes have improved understanding of gene function, biology, and evolutionary mechanisms. Hybrid genome assembly approaches leverage benefits of both long, relatively error-prone reads from third-generation sequencing technologies and short, accurate reads from second-generation sequencing technologies, to produce more accurate and contiguous de novo genome assemblies in comparison to using either technology independently. In this study, we present a novel hybrid assembly pipeline that allowed for both mitogenome de novo assembly and telomere length de novo assembly of all 7 chromosomes of the model entomopathogenic fungus, Metarhizium brunneum. RESULTS The improved assembly allowed for better ab initio gene prediction and a more BUSCO complete proteome set has been generated in comparison to the eight current NCBI reference Metarhizium spp. genomes. Remarkably, we note that including the mitogenome in ab initio gene prediction training improved overall gene prediction. The assembly was further validated by comparing contig assembly agreement across various assemblers, assessing the assembly performance of each tool. Genomic synteny and orthologous protein clusters were compared between Metarhizium brunneum and three other Hypocreales species with complete genomes, identifying core proteins, and listing orthologous protein clusters shared uniquely between the two entomopathogenic fungal species, so as to further facilitate the understanding of molecular mechanisms underpinning fungal-insect pathogenesis. CONCLUSIONS The novel assembly pipeline may be used for other haploid fungal species, facilitating the need to produce high-quality reference fungal genomes, leading to better understanding of fungal genomic evolution, chromosome structuring and gene regulation.
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Volatiles of the entomopathogenic fungus, Metarhizium brunneum, attract and kill plant parasitic nematodes.
Biological control : theory and applications in pest management, 2021Co-Authors: Salim Khoja, James C. Bull, Khalifa M. Eltayef, Ian H. Baxter, Arben Myrta, Tariq M. ButtAbstract:Abstract Root knot nematodes (RKNs) cause significant crop losses. Although RKNs and entomopathogenic fungi, such as Metarhizium brunneum, are associated with plant roots, very little is known about the interactions between these two organisms. This study showed that conidia and VOCs of Me. brunneum influenced the behaviour of M. hapla. The response was dependent on the fungal strain, VOC, concentration of both VOC and conidia, and time. Tomatoes planted in soil treated with the highest doses of conidia usually had a higher number of nematodes than untreated control plants. This was particularly obvious for Me. brunneum strain ARSEF 4556, 7 and 14-days post-treatment. The VOCs, 1-octen-3-ol and 3-octanone, lured M. hapla to plants when used at low doses and repelled them at high doses. In Petri dish assays. the VOCs 1-octen-3-ol and 3-octanone, caused 100% mortality of M. hapla at the highest dose tested (20 µl). Very few live M. hapla were recovered from soil treated with the VOC 1-octen-3-ol, especially at the highest doses tested.
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Telomere Length De Novo Assembly of all 7 Chromosomes and Mitogenome Sequencing of the Model Entomopathogenic Fungus, Metarhizium brunneum, by Means of a Novel Assembly Pipeline
2020Co-Authors: Zack Saud, Alexandra M. Kortsinoglou, Vassili N. Kouvelis, Tariq M. ButtAbstract:Abstract More accurate and complete reference genomes have improved understanding of gene function, biology, and evolutionary mechanisms. Hybrid genome assembly approaches leverage benefits of both long, relatively error-prone reads from third-generation sequencing technologies and short, accurate reads from second-generation sequencing technologies, to produce more accurate and contiguous de novo genome assemblies in comparison to using either technology independently. In this study, we present a novel hybrid assembly pipeline that allowed for both mitogenome de novo assembly and telomere length de novo assembly of all 7 chromosomes of the model entomopathogenic fungus, Metarhizium brunneum. The improved assembly allowed for better ab initio gene prediction and a more BUSCO complete proteome set has been generated in comparison to the eight current NCBI reference Metarhizium spp. genomes. Remarkably, we note that including the mitogenome in ab initio gene prediction training improved overall gene prediction. The assembly was further validated by comparing contig assembly agreement across various assemblers, assessing the assembly performance of each tool. Genomic synteny and orthologous protein clusters were compared between Metarhizium brunneum and three other Hypocreales species with complete genomes, identifying core proteins, and listing orthologous protein clusters shared uniquely between the two entomopathogenic fungal species, so as to further facilitate the understanding of molecular mechanisms underpinning fungal-insect pathogenesis. The novel assembly pipeline may be used for other haploid fungal species, facilitating the need to produce high-quality reference fungal genomes, leading to better understanding of fungal genomic evolution, chromosome structuring and gene regulation.
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action of Metarhizium brunneum hypocreales clavicipitaceae against organophosphate and pyrethroid resistant aedes aegypti diptera culicidae and the synergistic effects of phenylthiourea
Journal of Medical Entomology, 2019Co-Authors: Tariq M. Butt, Rodrigo Prado, Pamella A Macedosalles, Rodrigo Coutinho Duprat, Andrea Regina De Souza Baptista, Denise Feder, Jose Bento Pereira Lima, Norman A RatcliffeAbstract:Dengue, yellow fever, Zika, and chikungunya arboviruses are endemic in tropical countries and are transmitted by Aedes aegypti. Resistant populations of this mosquito against chemical insecticides are spreading worldwide. This study aimed to evaluate the biological effects of exposure of pesticide-sensitive Ae. aegypti larvae (Rockefeller) to conidia of the entomopathogen, Metarhizium brunneum, laboratory strains ARSEF 4556 and V275, and any synergistic activity of phenylthiourea (PTU). In addition, to investigate the nature of any cross-resistance mechanisms, these M. brunneum strains were tested against the Rockefeller larvae and two temephos- and deltamethrin-resistant wild mosquito populations from Rio de Janeiro. Treatment of Rockefeller larvae with 106 conidia/ml of ARSEF 4556 and V275 fungal strains resulted in significant decreased survival rates to 40 and 53.33%, respectively (P < 0.0001), compared with untreated controls. In contrast, exposure to 104 or 105 conidia/ml showed no such significant survival differences. However, the addition of PTU to the conidia in the bioassays significantly increased mortalities in all groups and induced a molt block. Experiments also showed no differences in Ae. aegypti mortalities between the fungal treated, wild pesticide-resistant populations and the Rockefeller sensitive strain. The results show the efficacy of M. brunneum in controlling Ae. aegypti larvae and the synergistic role of PTU in this process. Importantly, there was no indication of any cross-resistance mechanisms between Ae. aegypti sensitive or resistant to pesticides following treatment with the fungi. These results further support using M. brunneum as an alternative biological control agent against mosquito populations resistant to chemical insecticides.
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Comparison of different extraction kits to isolate microRNA from Galleria mellonella (wax moth) larvae infected with Metarhizium brunneum (ARSEF4556)
2019Co-Authors: Muneefah A. Alenezi, Tariq M. Butt, Daniel C. EastwoodAbstract:ABSTRACT MicroRNAs (miRNAs) play an important role in regulating gene expression and are involved in developmental processes in animals, plants and fungi. To understand the role of miRNAs in a biological system, it is important to optimise the extraction procedures to obtain high quality and quantity nucleic acid that enable high throughput sequencing and expression analysis. Numerous kit-based miRNA extraction protocols have been optimised generally to single cell or tissue cultures. Fungi, however, often occupy physically and chemically complex environments which miRNA make extraction challenging, such as fungal pathogens interacting within plant or animal host tissue. We used a Galleria mellonella (wax moth) larvae and entomopathogenic fungus Metarhizium brunneum ARSEF 4556 host/pathogen model to compare commercially available miRNA extraction kits (Invitrogen PureLink™ miRNA Isolation Kit, Ambion mirVana™miRNA Isolation Kit and Norgen microRNA purification Kit). Our results showed reproducible and significant differences in miRNAs extraction between the kits, with the Invitrogen PureLink™ miRNA Isolation protocol demonstrating the best performance in terms of miRNA quantity, quality and integrity isolated from fungus-infected insect tissue.
Anant V Patel - One of the best experts on this subject based on the ideXlab platform.
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Importance of phosphorus supply through endophytic Metarhizium brunneum for root:shoot allocation and root architecture in potato plants
Plant and Soil, 2018Co-Authors: Vivien Krell, Desirée Jakobs-schoenwandt, Stephan Unger, Anant V PatelAbstract:Background and aims Recent studies indicate the potential of endophytic entomopathogenic fungi to promote plant growth but little is known about the responses of root architecture to fungal endophytism. This study investigates potential adaptations of root architecture upon Metarhizium brunneum endophytism linked to improved plant growth and nutrition. Methods Plants ( Solanum tuberosum L.) were grown in the presence of M. brunneum applied either as non-formulated mycelium or as mycelium containing beads. After 35 days, fungal growth, root endophytism, plant biomass and nutrition as well as root attributes were determined. Results In response to endophytism promoted by bead application, plant P contents and biomass were significantly increased, while N contents and shoot allocation were also significantly increased in plants from the beads without mycelium group. Bead application resulted in a shift from fine to medium-sized roots and in an increase in the number of root forks, while root diameter, surface area and the number of root tips and crossings were independent of either bead or M. brunneum treatment. Conclusions M. brunneum containing beads supported endophytism allowing for increases in plant P contents and biomass. However, root architecture was not strongly modulated by M. brunneum endophytism with N provision through bead application being more important than fungal P delivery.
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Importance of phosphorus supply through endophytic Metarhizium brunneum for root:shoot allocation and root architecture in potato plants
Plant and Soil, 2018Co-Authors: Vivien Krell, Desirée Jakobs-schoenwandt, Stephan Unger, Anant V PatelAbstract:Recent studies indicate the potential of endophytic entomopathogenic fungi to promote plant growth but little is known about the responses of root architecture to fungal endophytism. This study investigates potential adaptations of root architecture upon Metarhizium brunneum endophytism linked to improved plant growth and nutrition. Plants (Solanum tuberosum L.) were grown in the presence of M. brunneum applied either as non-formulated mycelium or as mycelium containing beads. After 35 days, fungal growth, root endophytism, plant biomass and nutrition as well as root attributes were determined. In response to endophytism promoted by bead application, plant P contents and biomass were significantly increased, while N contents and shoot allocation were also significantly increased in plants from the beads without mycelium group. Bead application resulted in a shift from fine to medium-sized roots and in an increase in the number of root forks, while root diameter, surface area and the number of root tips and crossings were independent of either bead or M. brunneum treatment. M. brunneum containing beads supported endophytism allowing for increases in plant P contents and biomass. However, root architecture was not strongly modulated by M. brunneum endophytism with N provision through bead application being more important than fungal P delivery.
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Cellulase enhances endophytism of encapsulated Metarhizium brunneum in potato plants.
Fungal biology, 2018Co-Authors: Vivien Krell, Stefan Vidal, Desirée Jakobs-schoenwandt, Anant V PatelAbstract:Abstract The recent discovery that entomopathogenic fungi can grow endophytically in plant tissues has spurred research into novel plant protection measures. However, current applications of fungi aiming at endophytism mostly lack targeted formulation strategies resulting in low efficacy. Here, we aimed at enhancing Metarhizium brunneum CB15 endophytism in potato plants by (i) improvement of fungal growth from beads and (ii) cellulase formation or addition to encapsulated mycelium. We found that beads supplemented with cellulose alone or in addition with inactivated baker's yeast exhibited cellulase activity and increased mycelial growth by 12.6 % and 13.6 %, respectively. Higher enzymatic activity achieved by cellulase co-encapsulation promoted a shift from mycelial growth to spore formation with maximum numbers of 2.5 × 108 ± 6.1 × 107 per bead. This correlated with improved endophytism in potato plants by 61.2 % compared to non-supplemented beads. Our study provides first evidence that customized formulations of fungal entomopathogens with enzymes can improve endophytism and this may increase efficacy in plant protection strategies against herbivorous pests.
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Endophytic Metarhizium brunneum mitigates nutrient deficits in potato and improves plant productivity and vitality
Fungal Ecology, 2018Co-Authors: Vivien Krell, Desirée Jakobs-schoenwandt, Stephan Unger, Anant V PatelAbstract:Abstract There is growing evidence that entomopathogenic fungi play a role in plant growth promotion as colonizers of internal plant tissues. However, little is known about their potential to mitigate plant abiotic stress. Here, we investigated the influence of soil fertility on Metarhizium brunneum strain CB15 endophytism levels in potato plants linked to plant productivity and vitality. By application of encapsulated M. brunneum, the endophytism level, i.e. % presence of fungus in plant tissue, increased significantly under nutrient poor conditions. This correlated with significantly improved quantum yields of photosystem II. In addition, water use efficiency was increased with higher levels of M. brunneum endophytism. Furthermore, biomass, leaf area, nitrogen and phosphorus contents were enhanced indicating fungal nutrient mobilization and transfer. Our results provide first evidence for the role of entomopathogenic fungi in mitigating nutrient deficits in soil by improving plant productivity and vitality which may increase their use in plant protection strategies.
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Encapsulation of Metarhizium brunneum enhances endophytism in tomato plants
Biological Control, 2018Co-Authors: Vivien Krell, Stefan Vidal, Desirée Jakobs-schoenwandt, Anant V PatelAbstract:Abstract Biocontrol of insect pests using fungal entomopathogens has been promoted as a promising alternative to chemical pesticides. Apart from their direct mode of action against insect pests, several fungal entomopathogens have been reported as natural endophytes, paving the way for novel plant protection measures. In this study, we aimed at the selective propagation of finely dispersed Metarhizium brunneum strain BIPESCO5 mycelium in submerged culture and encapsulation in calcium alginate/starch beads to protect the fungus during drying, enable growth on different soils and promote endophytism in tomato plants. We found that a combination of osmotic pressure and increased medium viscosity promoted selective formation of finely dispersed mycelium reflected by 34.1-fold decreased pellet diameters, 1.8-fold increased mycelial biomass concentrations and low blastospore contents of 40.4 × 105 mL−1 after 48 h. Encapsulation of mycelium enhanced drying survival by 31.5%. Co-encapsulated starch was degraded by 24.8% after 21 days and served as a nutrient source for growth on soils with best results on sterile and non-sterile potting substrate with 8.7 mm and 4.4 mm radial mycelial growth, respectively, compared to water agar with 7.6 mm. When applied to the soil, encapsulation significantly increased endophytism 3.8–7.0-fold compared to plants treated with non-formulated fungal biomass. This study provides the first evidence of endophytic establishment of M. brunneum in the stem of tomato plants after application of mycelium to roots as well as on increased endophytism by encapsulation. These results might provide the basis for future work on increasing endophytism by formulation technologies.
Richard S Ostfeld - One of the best experts on this subject based on the ideXlab platform.
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the tick biocontrol agent Metarhizium brunneum m anisopliae strain f52 does not reduce non target arthropods
PLOS ONE, 2017Co-Authors: Ilya R Fischhoff, Felicia Keesing, Richard S OstfeldAbstract:Previous studies have found that Met52®, which contains the entomopathogenic fungus Metarhizium brunneum, is effective in reducing the abundance of Ixodes scapularis, the tick vector for the bacterium causing Lyme disease and for other tick-borne pathogens. Given widespread interest in effective, safe methods for controlling ticks, Met52 has the potential to be used at increasing scales. The non-target impacts of Met52, as applied for tick control, have not yet been assessed. A Before-After-Control-Impact experiment was conducted to assess the effects of Met52 on non-target arthropods in lawn and forest habitats typical of residential yards. Ground-dwelling arthropods were collected using bulk sampling of soil and litter, and pitfall sampling. Arthropods were sampled once before and twice after treatment of plots with either Met52 or water (control). Multivariate general linear models were used to jointly model the abundance of arthropod orders. For each sampling method and post-spray sampling occasion, Akaike Information Criterion values were used to compare the fits of two alternative models: one that included effects of period (before vs. after spray), habitat (lawn vs. forest), and treatment (Met52 vs. control), versus a nested null model that included effects of period, and habitat, but no treatment effect. The null model was consistently better supported by the data. Significant effects were found of period and habitat but not treatment. Retrospective power analysis indicated the study had 80% power to detect a 50% reduction in arthropod abundance, as measured by bulk samples taken before versus one week after treatment. The deployment of Met52 in suburban settings is unlikely to cause meaningful reductions in the abundance of non-target arthropods.
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The tick biocontrol agent Metarhizium brunneum (= M. anisopliae) (strain F52) does not reduce non-target arthropods.
PloS one, 2017Co-Authors: Ilya R Fischhoff, Felicia Keesing, Richard S OstfeldAbstract:Previous studies have found that Met52®, which contains the entomopathogenic fungus Metarhizium brunneum, is effective in reducing the abundance of Ixodes scapularis, the tick vector for the bacterium causing Lyme disease and for other tick-borne pathogens. Given widespread interest in effective, safe methods for controlling ticks, Met52 has the potential to be used at increasing scales. The non-target impacts of Met52, as applied for tick control, have not yet been assessed. A Before-After-Control-Impact experiment was conducted to assess the effects of Met52 on non-target arthropods in lawn and forest habitats typical of residential yards. Ground-dwelling arthropods were collected using bulk sampling of soil and litter, and pitfall sampling. Arthropods were sampled once before and twice after treatment of plots with either Met52 or water (control). Multivariate general linear models were used to jointly model the abundance of arthropod orders. For each sampling method and post-spray sampling occasion, Akaike Information Criterion values were used to compare the fits of two alternative models: one that included effects of period (before vs. after spray), habitat (lawn vs. forest), and treatment (Met52 vs. control), versus a nested null model that included effects of period, and habitat, but no treatment effect. The null model was consistently better supported by the data. Significant effects were found of period and habitat but not treatment. Retrospective power analysis indicated the study had 80% power to detect a 50% reduction in arthropod abundance, as measured by bulk samples taken before versus one week after treatment. The deployment of Met52 in suburban settings is unlikely to cause meaningful reductions in the abundance of non-target arthropods.
Dana Ment - One of the best experts on this subject based on the ideXlab platform.
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intraspecies variation of Metarhizium brunneum against the green peach aphid myzus persicae provides insight into the complexity of disease progression
Pest Management Science, 2021Co-Authors: Victoria Reingold, Chandrasekhar Kottakota, Nitsan Birnbaum, Malka Goldenberg, Galina Lebedev, Murad Ghanim, Dana MentAbstract:BACKGROUND Intensive application of chemical insecticides is required for aphid pest control. Among the biorational alternatives, entomopathogenic fungi are the most sustainable biocontrol agents; those of the order Hypocreales attack and cause fungal disease in arthropod hosts, with variations in host susceptibility attributed to both fungal and host characteristics. We evaluated inter- and intraspecies variations in Metarhizium spp. virulence and differences in fungal disease progression on adult and nymph stages of the green peach aphid, Myzus persicae (Sulzer), a parthenogenetically reproducing insect species. RESULTS Minor interspecies diversity was detected between the generalist Metarhizium species examined. Interestingly, significant intraspecies diversity was observed between Metarhizium brunneum isolates Mb7 and MbK. Infected adult aphids demonstrated similar disease progression for both isolates, mortality rates of more than 80% and fivefold reduction in fecundity. However, nymph mortality was detected only following MbK infection, with 50% mortality and significant reduction in molting rates. Confocal laser scanning microscopy demonstrated the variation in the disease stages of conidial adhesion and hemocoel colonization on each examined day post inoculation for each isolate. Significantly faster disease progression was observed in MbK-infected versus Mb7-infected nymphs, the latter demonstrating a higher percentage of uninfected nymphs accompanied with aphid molting. CONCLUSIONS The observed intraspecies variation suggests that altered conidial adhesion to the nymph cuticle is a major factor affecting virulence. We prove the role of nymph ecdysis as a defense mechanism disrupting fungal infection. Because significant differences were observed between closely related isolates, this study emphasizes the importance of appropriate isolate selection for biological control. © 2021 Society of Chemical Industry.
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Intraspecies variation of Metarhizium brunneum against the green peach aphid, Myzus persicae, provides insight into the complexity of disease progression.
Pest management science, 2021Co-Authors: Victoria Reingold, Chandrasekhar Kottakota, Nitsan Birnbaum, Malka Goldenberg, Galina Lebedev, Murad Ghanim, Dana MentAbstract:Background Intensive application of chemical insecticides is required for aphid pest control. Among the biorational alternatives, entomopathogenic fungi are the most sustainable biocontrol agents; those of the order Hypocreales attack and cause fungal disease in arthropod hosts, with variations in host susceptibility attributed to both fungal and host characteristics. We evaluated inter- and intraspecies variations in Metarhizium spp. virulence and differences in fungal disease progression on adult and nymph stages of the green peach aphid, Myzus persicae (Sulzer), a parthenogenetically reproducing insect species. Results Minor interspecies diversity was detected between the generalist Metarhizium species examined. Interestingly, significant intraspecies diversity was observed between Metarhizium brunneum isolates Mb7 and MbK. Infected adult aphids demonstrated similar disease progression for both isolates, mortality rates of more than 80% and fivefold reduction in fecundity. However, nymph mortality was detected only following MbK infection, with 50% mortality and significant reduction in molting rates. Confocal laser scanning microscopy demonstrated the variation in the disease stages of conidial adhesion and hemocoel colonization on each examined day post inoculation for each isolate. Significantly faster disease progression was observed in MbK-infected versus Mb7-infected nymphs, the latter demonstrating a higher percentage of uninfected nymphs accompanied with aphid molting. Conclusions The observed intraspecies variation suggests that altered conidial adhesion to the nymph cuticle is a major factor affecting virulence. We prove the role of nymph ecdysis as a defense mechanism disrupting fungal infection. Because significant differences were observed between closely related isolates, this study emphasizes the importance of appropriate isolate selection for biological control.
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Comparative response of Metarhizium brunneum to the cuticles of susceptible and resistant hosts
Archives of insect biochemistry and physiology, 2020Co-Authors: Dana Ment, Galina Gindin, Michael Samish, Itamar GlazerAbstract:Earlier studies demonstrated that Metarhizium brunneum, usually a broad-host pathogen of arthropods, is unable to complete its pathogenic life cycle when inoculated on the fungus-resistant tick, Hyalomma excavatum engorged females. While the fungus penetrates the cuticle of fungus-susceptible tick, Rhipicephalus annulatus females, it is unable to penetrate the cuticle of fungus-resistant tick, and even perishes on its surface. This is probably due to high concentration of antifungal fatty acids and probably also due to a hypersensitive-like response of the tick. To understand the metabolic pathways occurring in the fungal hyphae upon encountering the cuticles, we compared the response of the fungus to cuticle from susceptible and resistant tick cuticles by 2D-gels. The intracellular proteomes of M. brunneum Mb7 exposed to cuticle of the fungus-susceptible tick, R. annulatus, and to the fungus-resistant tick, H. excavatum engorged females were compared after exposure to either cuticles. By means of liquid chromatography-mass spectrometry/mass spectrometry we identified in both proteomes common proteins involved in biological processes as well as unique proteins identified only in the proteome of fungus exposed to fungus-resistant tick cuticle. These proteins were identified in high probability as heat shock proteins, four key enzymes of the glyoxylate cycle, and proteins associated with hypoxia, and exposure to antifungal drugs. These findings are discussed within the M. brunneum-tick pathosystem in relation to tick resistance and host resistance in general.
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Interactions of Metarhizium brunneum-7 with Phytophagous Mites Following Different Application Strategies.
Insects, 2020Co-Authors: Dana Ment, Sukirtha Raman, Shira Gal, David Ezra, Eric PalevskyAbstract:Metarhizium brunneum is a generalist entomopathogenic fungus known to be virulent against Acari. We investigated Metarhizium brunneum-7 (Mb7) interactions in three systems of phytophagous mites and their respective plant hosts: Volkamer lemon (Citrus volkameriana) and the citrus rust mite Phyllocoptruta oleivora; common bean (Phaseolus vulgaris) and the two-spotted spider mite Tetranychus urticae; and spring onion (Allium cepa) and the bulb mite Rhizoglyphus robini. All three mite species were susceptible to directly applied Mb7 conidia. Results obtained using the standard method for studying endophytic colonization vs. live confocal imaging of plant tissues using the green fluorescent protein (GFP)-transformed fungus differed markedly, demonstrating that microscopy validation was more definite than the standard process of recovery from plant tissue. Endophytic colonization was observed in conidium-infiltrated citrus leaves and in roots of onion plants treated with soil-drenched conidia, but not in common bean treated by either spray or drench of conidia. Endophytic colonization of citrus leaves did not affect the citrus mite population. Drench application in common bean reduced two-spotted mite population. Similarly, drench application in onion reduced bulb mite population. This study emphasizes the importance of the host plant effects on Mb7 control efficacy of mite pests, and the merits of live-imaging techniques in studying endophytic interaction.
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preventative approach to microbial control of capnodis tenebrionis by soil application of Metarhizium brunneum and beauveria bassiana
Insects, 2020Co-Authors: Dana Ment, Hysen Kokici, Enrico De LilloAbstract:Management of the Mediterranean flat-headed root-borer, Capnodis tenebrionis, is critical due to the larvae’s root localization. Neonate larvae can be exposed to natural enemies before penetrating the roots. Application of Metarhizium brunneum strain Mb7 and Beauveria bassiana strain GHA formulations on rice granules was investigated for their efficacy against C. tenebrionis larvae. Mb7 application, evaluated on apricot twigs, significantly and dose-dependently reduced colonization rates of neonates, with highest mortality at 108 conidia/g soil. Neonate susceptibility to Mb7 and GHA was evaluated on potted rootstocks (GF677 almond × peach, 2729 plum) planted in entomopathogenic fungi (EPF)-premixed soil (1.3–1.6 × 105 conidia/cm3 soil) or in EPF-free soil surface-treated with 5 g Mb7 fungal granules (1.25 × 109 conidia). Larval colonization rates were reduced 7.4-fold in 2729 by both fungi; only Mb7 completely prevented colonization of GF677 by larvae. Larvae inside plant galleries exhibited mycosis with EPF-treated soils and both fungi proliferated on larval frass. Mb7 conidia germinated in the rhizosphere of GF677, and conidia of both fungi remained viable throughout the trial. Galleria baiting technique was used on EPF-treated soil to evaluate EPF infectivity over time; Mb7 and GHA persisted 180 and 90 days post inoculation, respectively. The formulation (fungus-covered rice grains), delivery method (mixing with soil) and persistence (3–6 months) of Mb7 and GHA are feasible for potential field application to control C. tenebrionis.
Michael Samish - One of the best experts on this subject based on the ideXlab platform.
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Comparative response of Metarhizium brunneum to the cuticles of susceptible and resistant hosts
Archives of insect biochemistry and physiology, 2020Co-Authors: Dana Ment, Galina Gindin, Michael Samish, Itamar GlazerAbstract:Earlier studies demonstrated that Metarhizium brunneum, usually a broad-host pathogen of arthropods, is unable to complete its pathogenic life cycle when inoculated on the fungus-resistant tick, Hyalomma excavatum engorged females. While the fungus penetrates the cuticle of fungus-susceptible tick, Rhipicephalus annulatus females, it is unable to penetrate the cuticle of fungus-resistant tick, and even perishes on its surface. This is probably due to high concentration of antifungal fatty acids and probably also due to a hypersensitive-like response of the tick. To understand the metabolic pathways occurring in the fungal hyphae upon encountering the cuticles, we compared the response of the fungus to cuticle from susceptible and resistant tick cuticles by 2D-gels. The intracellular proteomes of M. brunneum Mb7 exposed to cuticle of the fungus-susceptible tick, R. annulatus, and to the fungus-resistant tick, H. excavatum engorged females were compared after exposure to either cuticles. By means of liquid chromatography-mass spectrometry/mass spectrometry we identified in both proteomes common proteins involved in biological processes as well as unique proteins identified only in the proteome of fungus exposed to fungus-resistant tick cuticle. These proteins were identified in high probability as heat shock proteins, four key enzymes of the glyoxylate cycle, and proteins associated with hypoxia, and exposure to antifungal drugs. These findings are discussed within the M. brunneum-tick pathosystem in relation to tick resistance and host resistance in general.
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Efficacy of the entomopathogenic fungus Metarhizium brunneum in controlling the tick Rhipicephalus annulatus under field conditions.
Veterinary Parasitology, 2014Co-Authors: Michael Samish, Dana Ment, Asael Rot, Itamar Glazer, S. Barel, Galina GindinAbstract:High infectivity of entomopathogenic fungi to ticks under laboratory conditions has been demonstrated in many studies. However, the few reports on their use under field conditions demonstrate large variations in their success, often with no clear explanation. The present study evaluated the factors affecting the efficacy of the fungus Metarhizium brunneum against the tick Rhipicephalus (Boophilus) annulatus. It demonstrates how environmental conditions and ground cover affect the efficiency of the fungus under field conditions. During the summer, 93% of tick females exposed to fungus-contaminated ground died within 1 week, whereas during the winter, only 62.2% died within 6 weeks. Nevertheless, the hatchability of their eggs was only 6.1% during the summer and 0.0% during winter. Covering the ground with grass, leaves or gravel improved fungal performance. Aside from killing female ticks, the fungus had a substantial effect on tick fecundity. Fungal infection reduced the proportion of female ticks laying full-size egg masses by up to 91%, and reduced egg hatchability by up to 100%. To reduce the negative effect of outdoor factors on fungal activity, its conidia were mixed with different oils (olive, canola, mineral or paraffin at 10% v/v) and evaluated in both laboratory and field tests for efficacy. All tested oils without conidia sprayed on the sand did not influence tick survival or weight of the laid eggs but significantly reduced egghatchability. Conidia in water with canola or mineral oil spread on agarose and incubated for 18 h showed 57% and 0% germination, respectively. Comparing, under laboratory conditions, the effects of adding each of the four oils to conidia in water on ticks demonstrated no effect on female mortality or weight of the laid egg mass, but the percentage of hatched eggs was reduced. In outdoor trials, female ticks placed on the ground sprayed with conidia in water yielded an average of 175 larvae per female and there was no hatching of eggs laid by females placed on ground sprayed with conidia in water with canola or mineral oils.
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On-host control of the brown dog tick Rhipicephalus sanguineus Latreille (Acari: Ixodidae) by Metarhizium brunneum (Hypocreales: Clavicipitaceae).
Veterinary Parasitology, 2012Co-Authors: Asael Rot, Galina Gindin, Dana Ment, Itamar Glazer, A. Mishoutchenko, Michael SamishAbstract:Abstract Ticks are obligatory blood-sucking arthropods. Their life cycle includes a relatively short period of feeding on a vertebrate host and a long off-host period spent in the upper layer of the soil. Entomopathogenic fungi are known to be highly effective tick pathogens and the on-host application of these fungi may be a promising economic approach for tick control. In this study, we evaluated the tick control provided by spraying Metarhizium brunneum onto the tick's vertebrate host, specifically gerbils ( Meriones tristrami ) and rabbits ( Oryctolagus cuniculus ). The efficacy of the fungal treatment was not limited to a direct effect on the mortality of feeding ticks, but continued during molting (off host) and, in the case of female ticks, the treatment reduced the production of eggs and their hatching rate. The direct control of the on-host stages was relatively low (from 19 to 38%); whereas the effects of the applied fungus on subsequent tick development reduced the yield of the following engorged stages up to 30–63%. Engorged females that dropped from rabbits sprayed with M. brunneum laid 21.5% fewer eggs than the control females. Moreover, these ticks transmitted conidia by contact to the eggs which they laid, resulting a 3-fold reduction in the rate of hatching relative to the control. Based on theoretical cumulative calculations, these results suggest that if the progeny of each unfed stage feed on fungus-sprayed hosts, there will be a 92% reduction in the tick population within one generation. Two spray formulations, one based on mineral oil and another based on a starch–sucrose mixture, significantly enhanced on-host tick control, in comparison with an unformulated conidial suspension. The reduction in the number of nymphs that fed on the treated host and later developed into unfed adults was 54.9% for unformulated conidia, 70.4% for the oil formulation and 86.4% for the starch–sucrose formulation. Increasing the environmental humidity around the gerbils while the ticks fed on them to 90% RH significantly improved the control of the on-host developmental stages, reducing the number of engorged ticks that dropped from fungus-sprayed gerbils 3-fold in comparison with the same animals kept at 30–60% RH. There was no difference between the efficacy of the observed tick control at an ambient temperature of 21 °C and that observed at 28 °C.