Metarhizium robertsii

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Metarhizium robertsii
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Hypocreales
Family: Clavicipitaceae
Genus: Metarhizium
Species:
M. robertsii
Binomial name
Metarhizium robertsii

Metarhizium robertsii is a fungus that grows naturally in soils throughout the world and causes disease in various insects by acting as a parasitoid. It is a mitosporic fungus with asexual reproduction, which was formerly classified in the form class Hyphomycetes of the phylum Deuteromycota (also often called fungi imperfecti).

Many isolates have long been recognised to be specific, and they were assigned variety status, [1] but they have now been assigned as new Metarhizium species in light of new molecular evidence; [2] one of these was M. robertsii. Other examles were M. majus and M. acridum (which was M. anisopliae var. acridum and included the isolates used for locust control). Metarhizium taii was placed in M. anisopliae var. anisopliae, [3] but has now been described as a synonym of M. guizhouense (see Metarhizium ). The commercially important isolate M.a. 43 (or F52, Met52, etc.), which infects Coleoptera and other insect orders has now been assigned to Metarhizium brunneum . [4]

Important isolates

M. robertsii was named after Prof. Donald W. Roberts, who’s PhD dissertation focused on destruxins of the insect-pathogenic fungus then called " Metarhizium anisopliae "; Don continued to work with entomopathogenic fungi, as a research professor, working especially with an isolate called ARSEF 23: which eventually became the type for this species. [5]

Biology

Insect diseases caused by fungi in this genus is sometimes called green muscardine disease because of the green colour of their spores. When these mitotic (asexual) spores (called conidia) of the fungus come into contact with the body of an insect host, they germinate and the hyphae that emerge penetrate the cuticle. The fungus then develops inside the body, eventually killing the insect after a few days; this lethal effect is very likely aided by the production of insecticidal cyclic peptides (destruxins). The cuticle of the cadaver often becomes red. If the ambient humidity is high enough, a white mould then grows on the cadaver that soon turns green as spores are produced. Most insects living near the soil have evolved natural defenses against entomopathogenic fungi like M. robertsii. This fungus is, therefore, locked in an evolutionary battle to overcome these defenses, which has led to a large number of isolates (or strains) that are adapted to certain groups of insects. [6]

Economic importance

A simplified method of microencapsulation has been demonstrated to increase the shelf-life of M. robertsii spores commercialised for biological control of pest insects, potentially increasing its efficiency against red imported fire ants. [7]

M. Robertsii has been shown to break down very toxic mercury into less toxic forms of mercury. The fungus has been genetically engineered to improve its ability to perform this task. [8]

See also

Related Research Articles

<i>Beauveria bassiana</i> Species of fungus

Beauveria bassiana is a fungus that grows naturally in soils throughout the world and acts as a parasite on various arthropod species, causing white muscardine disease; it thus belongs to the group of entomopathogenic fungi. It is used as a biological insecticide to control a number of pests, including termites, thrips, whiteflies, aphids and various beetles. Its use in the control of bed bugs and malaria-transmitting mosquitos is under investigation.

<span class="mw-page-title-main">Entomopathogenic fungus</span> Fungus that can act as a parasite of insects

An entomopathogenic fungus is a fungus that can kill or seriously disable insects.

Hyphomycetes are a form classification of fungi, part of what has often been referred to as fungi imperfecti, Deuteromycota, or anamorphic fungi. Hyphomycetes lack closed fruit bodies, and are often referred to as moulds. Most hyphomycetes are now assigned to the Ascomycota, on the basis of genetic connections made by life-cycle studies or by phylogenetic analysis of DNA sequences; many remain unassigned phylogenetically.

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Raymond J. St. Leger is an American mycologist, entomologist, molecular biologist and biotechnologist who currently holds the rank of Distinguished University Professor in the Department of Entomology at the University of Maryland, College Park.

<i>Metarhizium</i> Genus of fungi

Metarhizium is a genus of entomopathogenic fungi in the Clavicipitaceae family. With the advent of genetic profiling, placing these fungi in proper taxa has now become possible. Most turn out to be the asexual forms (anamorphs) of fungi in the phylum Ascomycota, including Metacordyceps spp.

<span class="mw-page-title-main">LUBILOSA</span>

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<i>Metarhizium acridum</i> Grasshopper- and locust-killing fungus

Metarhizium acridum is the new name given to a group of fungal isolates that are known to be virulent and specific to the Acrididea (grasshoppers). Previously, this species has had variety status in Metarhizium anisopliae ; before that, reference had been made to M. flavoviride or Metarhizium sp. describing an "apparently homologous and distinctive group" of isolates that were most virulent against Schistocerca gregaria in early screening bioassays.

<i>Metarhizium majus</i> Species of fungus

Metarhizium majus is the name given to a group of fungal isolates that are known to be virulent against Scarabaeidae, a family of beetles. Previously, this species has had variety status in Metarhizium anisopliae and its name is derived from characteristically very large spores for the genus Metarhizium. There has been considerable interest in developing isolates of this species into mycoinsecticides: especially against the coconut and oil palm beetle pest Oryctes in SE Asia, the Pacific region and Africa.

<i>Metarhizium flavoviride</i> Species of fungus

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<span class="mw-page-title-main">Muscardine</span> Fungal disease of insects

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Metarhizium brunneum is the re-instated name of a group of reassigned Metarhizium isolates, previously grouped in the species "Metarhizium anisopliae var. anisopliae": based on a multigene phylogenetic approach using near-complete sequences from nuclear DNA. It is a mitosporic fungus with asexual reproduction, which was formerly classified in the form class Hyphomycetes of the form phylum Deuteromycota. M. brunneum has been isolated from Coleoptera, Lepidoptera, Diptera and soil samples, but a commercially developed isolate (below) has proved virulent against Hemiptera and Thysanoptera.

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Tariq Butt is a British entomologist. He is a Professor of Biosciences at Swansea University in Wales.

Donald W. Roberts was an American insect pathologist and one of the originators of that field. He was especially known for research into biological pest control of Lepidoptera by Metarhizium but also Beauveria bassiana. He was a Research Professor Emeritus in the Biology Department of Utah State University.

<i>Metarhizium anisopliae</i> Species of fungus

Metarhizium anisopliae is the type species in its genus of fungi, that grows naturally in soils throughout the world and causes disease in various insects by acting as a parasitoid. Ilya I. Mechnikov named it Entomophthora anisopliae (basionym) after the insect species from which it was originally isolated – the beetle Anisoplia austriaca and from these early days, fungi such as this have been seen as potentially important tools for pest management. It is a mitosporic fungus with asexual reproduction, which was formerly classified in the form class Hyphomycetes of the phylum Deuteromycota.

Batkoa major is a naturally occurring fungus.

References

  1. Driver, F.; Milner, R.J. & Trueman, W.H.A. (2000). "A Taxonomic revision of Metarhizium based on sequence analysis of ribosomal DNA". Mycological Research. 104 (2): 135–151. doi:10.1017/S0953756299001756.
  2. Bischoff J.F.; Rehner S.A. Humber R.A. (2009). "A multilocus phylogeny of the Metarhizium anisopliae lineage". Mycologia. 101 (4): 512–530. doi:10.3852/07-202. PMID   19623931. S2CID   28369561. Archived from the original on 2020-08-19. Retrieved 2018-12-29.
  3. Huang B.; Li C.; Humber R.A.; Hodge K.T.; Fan M.; Li Z. (2005). "Molecular evidence for the taxonomic status of Metarhizium taii and its teleomorph, Cordyceps taii (Hypocreales, Clavicipitaceae)". Mycotaxon. 94: 137–147.
  4. GVP Reddy; Z Zhao; RA Humber (2014). "Laboratory and field efficacy of entomopathogenic fungi for the management of the sweet potato weevil, Cylas formicarius (Coleoptera: Brentidae)". Journal of Invertebrate Pathology. 122: 10–15. doi: 10.1016/j.jip.2014.07.009 . PMID   25111763.
  5. "Home - Metarhizium robertsii ARSEF 23". MycoCosm, JGI, US DOE.
  6. Freimoser, F. M.; Screen, S.; Bagga, S.; Hu, G. & St. Leger, R.J. (2003). "EST analysis of two subspecies of M. anisopliae reveals a plethora of secreted proteins with potential activity in insect hosts". Microbiology. 149 (Pt 1): 239–247. doi: 10.1099/mic.0.25761-0 . PMID   12576597.
  7. Qiu, Hua-Long; Fox, Eduardo G. P.; Qin, Chang-Sheng; Zhao, Dan-Yang; Yang, Hua; Xu, Jin-Zhu (2019-07-01). "Microcapsuled entomopathogenic fungus against fire ants, Solenopsis invicta" (PDF). Biological Control. 134: 141–149. doi:10.1016/j.biocontrol.2019.03.018. ISSN   1049-9644. S2CID   132021733.
  8. Wu, Congcong; Tang, Dan; Dai, Jin; Tang, Xingyuan; Bao, Yuting; Ning, Jiali; Zhen, Qing; Song, Hui; St. Leger, Raymond J.; Fang, Weiguo (2022). "Bioremediation of mercury-polluted soil and water by the plant symbiotic fungus Metarhizium robertsii". Proceedings of the National Academy of Sciences. 119 (47). doi: 10.1073/pnas.2214513119 . PMC   9704736 . PMID   36375055. S2CID   253522740.