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Journal ArticleDOI

Microbial Biocontrol Strategies for Ambrosia Beetles and Their Associated Phytopathogenic Fungi

TL;DR: A review of existing knowledge on biocontrol approaches using beneficial microorganisms and microbial natural products with entomopathogenic and antifungal activity against ambrosia beetles and fungi is presented in this paper.
Abstract: Ambrosia beetles and their symbiotic fungi are causing severe damage in natural and agro-ecosystems worldwide, threatening the productivity of several important tree crops such as avocado. Strategies aiming at mitigating their impact include the application of broad-spectrum agrochemicals and the incineration of diseased trees, but the increasing demand for environment-friendly strategies call for exploring biological control for the management of ambrosia beetles and their phytopathogenic fungal symbionts. The aim of this review is to examine the existing knowledge on biocontrol approaches using beneficial microorganisms and microbial natural products with entomopathogenic and antifungal activity against ambrosia beetles and fungi. We show that biocontrol has been mainly focused on the insect, using entomopathogenic fungi (EPF) such as Beauveria spp. or Metarhizium spp. However, recent studies have been integrating EPF with mycoparasitic fungi such as Trichoderma spp. to simultaneously challenge the vector and its fungal symbionts. Novel approaches also include the use of microbial natural products as insect lures or antifungal agents. Contrastingly, the potential of bacteria, including actinobacteria (actinomycetes), as biocontrol agents of ambrosia fungi has been little investigated. We thus suggest that future research should further examine the antifungal activity of bacterial strains, with an emphasis on harsh environments. We also suggest pursuing the isolation of more effective microbial strains with dual biocontrol effect, i.e. exhibiting fungicidal/insecticidal activities. Moreover, additional efforts should aim at determining the best application methods of biocontrol agents in the field to ensure that the positive effects detected in vitro are sustained. Finally, we propose the integration of microbiome studies in pest and disease management strategies as they could provide us with tools to steer the beneficial host plant microbiome and to manipulate the beetle microbiome in order to reduce insect fitness.

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Citations
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Journal ArticleDOI
TL;DR: The antifungal activity displayed by pennogenin tetraglycoside against F. kuroshium is highlighted, since it is the first plant natural product identified as active for this phytopathogen.
Abstract: Antifungal assay-guided fractionation of the methanolic crude extract of Cestrum nocturnum (Solanaceae), popular known as ‘lady of the night’, led the isolation and identification of the steroidal saponin named pennogenin tetraglycoside, which was identified for the first time in this plant species by spectroscopic means. The crude extract, fractions and pennogenin tetraglycoside exhibited mycelial growth inhibition of Fusarium solani and F. kuroshium. F. solani is a cosmopolitan fungal phytopathogen that affects several economically important crops. However, we highlight the antifungal activity displayed by pennogenin tetraglycoside against F. kuroshium, since it is the first plant natural product identified as active for this phytopathogen. This fungus along with its insect symbiont known as Kuroshio shot hole borer (Euwallacea kuroshio) are the causal agents of the plant disease Fusarium dieback that affects more than 300 plant species including avocado (Persea americana) among others of ecological relevance. Scanning electron microscopy showed morphological alterations of the fungal hyphae after exposure with the active fractions and 12 phenolic compounds were also identified by mass spectrometry dereplication as part of potential active molecules present in C. nocturnum leaves.

5 citations

Journal ArticleDOI
TL;DR: The results emphasize the potential of natural products from Bacillus for the control of emerging phytopathogenic fungi F. kuroshium, causal agent of Fusarium dieback in avocado and other hosts.
Abstract: Antimicrobial compounds produced by bacteria have been increasingly acknowledged as an important resource for the control of phytopathogens. We used a bioassay‐guided fractionation approach to identify antifungal metabolites produced by two avocado rhizobacteria (INECOL‐4742 and INECOL‐5927), both members of the Bacillus subtilis/B. amyloliquefaciens species complex, against Fusarium solani and F. kuroshium, causal agent of Fusarium dieback in avocado and other hosts. The butanol (BuOH) organic extract from INECOL‐4742 (B1‐Bu) exhibited the highest percentage of inhibition (PI) against F. solani (78.76 %), also inhibiting F. kuroshium by up to 44.30 %. Primary fractions, Bu‐F3, Bu‐F12 and Bu‐F15, obtained by silica gel open column chromatography, exhibited the highest PI against F. solani (28.57 % to 33.50 %) and F. kuroshium (38.78 % to 45.00 %). The presence of cyclic lipopeptides from the iturin, surfactin and fengycin families in B1‐Bu extracts and primary fractions was determined by UPLC‐ESI‐HRMS. The Confocal Laser Microscopy analysis revealed deformations in the hyphae of F. kuroshium exposed to extracts, primary fractions and C‐13 surfactin chemical standard. These results emphasize the potential of natural products from Bacillus for the control of the emerging phytopathogenic fungus F. kuroshium.

2 citations

Journal ArticleDOI
TL;DR: In this paper , the authors elaborate consortia from selected rhizospheric and endophytic bacteria with antifungal and plant growth promoting properties, and evaluate their beneficial effects on the growth of Physalis ixocarpa.

2 citations

Journal ArticleDOI
TL;DR: The antifungal and insecticidal properties of 34 extracts from 27 plant species were evaluated against fungal phytopathogens of the genus Fusarium and Xyleborus Scolytine ambrosia beetles involved in fusarium dieback and laurel wilt (LW) diseases as mentioned in this paper .
Abstract: The antifungal and insecticidal activities of 34 extracts from 27 plant species were evaluated against fungal phytopathogens of the genus Fusarium and Xyleborus Scolytine ambrosia beetles involved in Fusarium dieback (FD) and laurel wilt (LW) diseases. Sixteen extracts caused mycelial growth inhibition (MGI) above 23 % at 2 mg mL−1 against F. solani, those from S. nudum and M. argyrophylla exhibited the highest MGI (57 % and 49 %, respectively). Thirteen extracts displayed significant antifungal activity against F. kuroshium, those from C. nocturnum and M. argyrophylla exhibited the highest MGI (100 % and 54.9 %, respectively). Additionally, ten plants extracts caused mortality in at least one of the beetle species tested, mainly from Solanaceae species. In the most active species, 39 phenolics were identified that may have contributed to their biological effects. This study is one of the first to report the potential of plant‐derived natural products against the causative agents of FD and LW.
Journal ArticleDOI
01 Apr 2023-Insects
TL;DR: In this paper , the authors investigated the efficacy of commercialized entomopathogenic products against the Euwallacea fornicatus and found that although effective under lab conditions, currently recommended field application methods of these products to the outer bark of trees have limited effects on beetle survival and reproduction.
Abstract: Simple Summary The accidental introduction of the ambrosia beetle Euwallacea fornicatus and its fungal symbiont, Fusarium euwallaceae, into Israel, the United States and South Africa has had a devastating impact on many economically and ornamentally important tree species. Currently, there is no effective control measure in place to control this beetle pest and its symbiont. As a first step towards controlling this beetle in South Africa, this study investigated the efficacy of commercialized entomopathogenic products against the beetle. Results showed that although effective under lab conditions, currently recommended field application methods of these products to the outer bark of trees have limited effects on beetle survival and reproduction. Abstract The invasive ambrosia beetle, Euwallacea fornicatus, was first reported in South Africa in 2018. The beetle has now spread to eight provinces of the country and has had a devastating impact on both native and non-native tree species. This is especially true for trees located in urban and peri-urban environments. Recent predictions are that the South African E. fornicatus invasion will cost an estimated ZAR 275 billion (approx. USD 16 billion) if it continues to spread uncontrollably, justifying an urgent need for its effective management in the country. One option is biological control, which is preferred over the use of chemicals due to its lower environmental impact. We tested two broad-spectrum fungal entomopathogenic agents, Eco-Bb® and Bio-Insek, which are commercially available in South Africa, for efficacy against E. fornicatus. Initial laboratory assays yielded promising results. However, beetle infestation trials using treated pieces of woody castor bean stems showed little effect on beetle survival and reproduction.
References
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Journal ArticleDOI
27 May 2011-Science
TL;DR: It is indicated that upon attack by a fungal root pathogen, plants can exploit microbial consortia from soil for protection against infections.
Abstract: Disease-suppressive soils are exceptional ecosystems in which crop plants suffer less from specific soil-borne pathogens than expected owing to the activities of other soil microorganisms. For most disease-suppressive soils, the microbes and mechanisms involved in pathogen control are unknown. By coupling PhyloChip-based metagenomics of the rhizosphere microbiome with culture-dependent functional analyses, we identified key bacterial taxa and genes involved in suppression of a fungal root pathogen. More than 33,000 bacterial and archaeal species were detected, with Proteobacteria, Firmicutes, and Actinobacteria consistently associated with disease suppression. Members of the γ-Proteobacteria were shown to have disease-suppressive activity governed by nonribosomal peptide synthetases. Our data indicate that upon attack by a fungal root pathogen, plants can exploit microbial consortia from soil for protection against infections.

1,948 citations

Journal ArticleDOI
Julia A. Vorholt1
TL;DR: Insights into the underlying structural principles of indigenous microbial phyllosphere populations will help to develop a deeper understanding of the phyllospheric microbiota and will have applications in the promotion of plant growth and plant protection.
Abstract: Our knowledge of the microbiology of the phyllosphere, or the aerial parts of plants, has historically lagged behind our knowledge of the microbiology of the rhizosphere, or the below-ground habitat of plants, particularly with respect to fundamental questions such as which microorganisms are present and what they do there. In recent years, however, this has begun to change. Cultivation-independent studies have revealed that a few bacterial phyla predominate in the phyllosphere of different plants and that plant factors are involved in shaping these phyllosphere communities, which feature specific adaptations and exhibit multipartite relationships both with host plants and among community members. Insights into the underlying structural principles of indigenous microbial phyllosphere populations will help us to develop a deeper understanding of the phyllosphere microbiota and will have applications in the promotion of plant growth and plant protection.

1,450 citations

Journal ArticleDOI
TL;DR: Based on the present knowledge it is concluded that both Beauveria species are considered to be safe.
Abstract: The commercial use of entomopathogenic fungi and their products as mycoinsecticides necessitates their registration. Worldwide, several registration guidelines are available, however, most of them focus on similar or even the same safety issues. With respect to the two entomopathogenic fungi, Beauveria bassiana (Bals.-Criv.) Vuill. and Beauveria brongniartii (Sacc.) Petch, many commercial products have been developed, and numerous papers on different biological, environmental, toxicological and other safety aspects have been published during the past 30–40 years. The aim of the present review is to summarise these data. The following safety issues are presented: (1) identity of Beauveria spp.; (2) biological properties of Beauveria spp. (history, natural occurrence and geographical distribution, host range, mode of action, production of metabolites/toxins, effect of environmental factors); (3) analytical methods to determine and quantify residues; (4) fate and behaviour in the environment (mobili...

528 citations

Journal ArticleDOI
TL;DR: Artificial mixtures of the fungal VOCs were both inhibitory and lethal to a number of human and plant pathogens, including three drug-resistant strains of Mycobacterium tuberculosis.
Abstract: Muscodor crispans is a recently described novel endophytic fungus of Ananas ananassoides (wild pineapple) growing in the Bolivian Amazon Basin. The fungus produces a mixture of volatile organic compounds (VOCs); some of the major components of this mixture, as determined by GC/MS, are propanoic acid, 2-methyl-, methyl ester; propanoic acid, 2-methyl-; 1-butanol, 3-methyl-;1-butanol, 3-methyl-, acetate; propanoic acid, 2-methyl-, 2-methylbutyl ester; and ethanol. The fungus does not, however, produce naphthalene or azulene derivatives as has been observed with many other members of the genus Muscodor. The mixture of VOCs produced by M. crispans cultures possesses antibiotic properties, as does an artificial mixture of a majority of the components. The VOCs of the fungus are effective against a wide range of plant pathogens, including the fungi Pythium ultimum, Phytophthora cinnamomi, Sclerotinia sclerotiorum and Mycosphaerella fijiensis (the black sigatoka pathogen of bananas), and the serious bacterial pathogen of citrus, Xanthomonas axonopodis pv. citri. In addition, the VOCs of M. crispans killed several human pathogens, including Yersinia pestis, Mycobacterium tuberculosis and Staphylococcus aureus. Artificial mixtures of the fungal VOCs were both inhibitory and lethal to a number of human and plant pathogens, including three drug-resistant strains of Mycobacterium tuberculosis. The gaseous products of Muscodor crispans potentially could prove to be beneficial in the fields of medicine, agriculture, and industry.

473 citations

Journal ArticleDOI
TL;DR: All relevant safety data of this fungus are summarized, and M. anisopliae is considered to be safe with minimal risks to vertebrates, humans and the environment.
Abstract: The entomopathogenic fungus Metarhizium anisopliae (Metschn.) Sorokin is widely used for biocontrol of pest insects, and many commercial products are on the market or under development. The aim of this review is to summarise all relevant safety data of this fungus, which are necessary for the commercialisation and registration process. The review contains the following sections: (1) identity, (2) biological properties (history, natural occurrence and geographical distribution, host range, mode of action, production of metabolites/toxins, effect of environmental factors), (3) methods to determine and quantify residues, (4) fate and behaviour in the environment (mobility and persistence in air, water and soil), (5) effects on non-target organisms (microorganisms, plants, soil organisms, aquatic organisms, predators, parasitoids, honey bees, earth worms, etc.), (6) effects on vertebrates (fish, amphibia, reptiles, and birds), and (7) effects on mammals and human health (allergy, pathogenicity/toxici...

449 citations

Trending Questions (3)
Ambrosia beetles associated with the fungus pathogenic which lead to economical damage of the tree

The paper does not specifically mention a fungus pathogenic to ambrosia beetles that leads to economic damage to trees. The paper focuses on exploring biocontrol strategies using beneficial microorganisms and microbial natural products against ambrosia beetles and their associated phytopathogenic fungi.

Ambrosia beetles ASSOCIATED WITH DIFERENT FUNGUS PATHOGINIC AND VECTOR IT

The paper does not provide specific information about ambrosia beetles associated with different pathogenic fungi. The paper focuses on biocontrol strategies for ambrosia beetles and their fungal symbionts.

Ambrosia beetles difficult control

The paper does not directly answer the question about the difficulty of controlling ambrosia beetles. The paper focuses on exploring biocontrol strategies using beneficial microorganisms and microbial natural products against ambrosia beetles and their associated fungi.