''Metarhizium anisopliae'' is a fungus, the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

in the ''

Metarhizium ''Metarhizium'' is a genus (biology), genus of entomopathogenic fungus, entomopathogenic fungi in the family Clavicipitaceae. With the advent of genetic profiling, placing these fungi in proper taxa has now become possible. Most turn out to be ...

'' genus. It grows naturally in soils throughout the world and causes disease in various

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s by acting as a

parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

. Ilya I. Mechnikov named it ''Entomophthora anisopliae'' after the insect species from which it was originally isolated – the

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

'' Anisoplia austriaca'' and from these early days, fungi such as this have been seen as potentially important tools for

pest management Pest control is the regulation or management of a species defined as a pest; such as any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the damage done and wi ...

. It is a mitosporic fungus with

asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the f ...

Synonymy

The taxonomy of the ''

'' has been subject to many reviews since the 1990s, before which the genus consisted of less than ten "species", based on morphological characteristics only. Many isolates have long been recognised to be specific, and some were initially assigned

variety Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...

status, with ''M. anisopliae'' ''

sensu stricto ''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...

'', '' M.a. var. major'', '' M.a. var. lepidiotae'' and '' M.a. var. acridum'' (the latter included important isolates used for locust control). However, they have now been assigned as new ''Metarhizium'' species in light of newer molecular evidence and subsequent work. The commercially important isolate M.a. 43 (or F52, Met52, etc.), which infects

Coleoptera Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

and other insect orders has now been assigned to '' Metarhizium brunneum''.

Biology

The disease caused by the fungus is sometimes called green muscardine disease because of the green colour of its

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s. When these mitotic (asexual) spores (called

conidia A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...

) of the fungus come into contact with the body of an insect host, they germinate and the

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

e that emerge penetrate the

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

. 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

peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...

s (destruxins). The cuticle of the cadaver often becomes red. If the ambient humidity is high enough, a white

mould A mold () or mould () is one of the structures that certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi ...

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. anisopliae''. 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.

Economic importance

The previously described range of

entomopathogenic fungus Entomopathogenic fungi are parasitic unicellular or multicellular microorganisms belonging to the kingdom of Fungi, that can infect and seriously disable or kill insects. Pathogenicity for insects is widely distributed in the kingdom of fungi and ...

isolates known as ''M. anisopliae'', before 2009, had been observed to infect over 200 insect pest species. ''M. anisopliae'' and its related species are used as biological insecticides to control a number of pests such as

termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...

thrips Thrips (Order (biology) , order Thysanoptera) are minute (mostly long or less), slender insects with fringed wings and unique asymmetrical mouthparts. Entomologists have species description , described approximately 7,700 species. They fly on ...

, etc. and its use in the control of

malaria Malaria is a Mosquito-borne disease, mosquito-borne infectious disease that affects vertebrates and ''Anopheles'' mosquitoes. Human malaria causes Signs and symptoms, symptoms that typically include fever, Fatigue (medical), fatigue, vomitin ...

-transmitting

mosquito Mosquitoes, the Culicidae, are a Family (biology), family of small Diptera, flies consisting of 3,600 species. The word ''mosquito'' (formed by ''Musca (fly), mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mos ...

es is under investigation. A modified form was reported to kill 90% of females who mated with infected males in a study in

Burkina Faso Burkina Faso is a landlocked country in West Africa, bordered by Mali to the northwest, Niger to the northeast, Benin to the southeast, Togo and Ghana to the south, and Ivory Coast to the southwest. It covers an area of 274,223 km2 (105,87 ...

. ''M. anisopliae'' does not appear to infect humans but has been reported as a significant pathogen of reptiles. The microscopic spores are typically sprayed on affected areas. A possible technique for malaria control is to coat

mosquito net A mosquito net is a type of meshed curtain or cloth that is circumferentially draped over a bed or a sleeping area to offer the sleeper barrier protection against bites and stings from mosquitos, flies, and other pest insects, and thus a ...

s or cotton sheets attached to the wall with them. According to

Paul Stamets Paul Edward Stamets (born July 17, 1955) is an American mycologist and entrepreneur who sells various mushroom products through his company. He is an author and advocate of medicinal fungi and mycoremediation. Early and personal life Stame ...

, species such as this could prevent

colony collapse disorder Colony collapse disorder (CCD) is an abnormal phenomenon that occurs when the majority of worker bees in a honey bee bee colony, colony disappear, leaving behind a queen bee, queen, plenty of food, and a few nurse bees to care for the remaining ...

and catastrophic famine. A simplified method of microencapsulation has been demonstrated to increase the shelf-life of ''M. anisopliae'' spores commercialised for biological control of pest insects, potentially increasing its efficiency against

red imported fire ant ''Solenopsis invicta'', the fire ant, or red imported fire ant (RIFA), is a species of ant native to South America. A member of the genus ''Fire ant, Solenopsis'' in the subfamily Myrmicinae, it was Species description, described by Swiss ento ...

s. The species has been shown to convert elemental

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

, an environmental pollutant, into the much less toxic

pyromorphite Pyromorphite is a mineral species composed of lead chlorophosphate: Pb5( P O4)3 Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead. Crystals are common, and have the form of a hexagonal prism terminated by the basal p ...

, thus showing its potential use in decontamination.

Important isolates

Some isolates previously placed here have been assigned to '' Metarhizium robertsii''; others may include: * The ex-neotype isolate of ''M. anisopliae'' is IMI 168777ii = ARSEF 7487 (also CSIRO FI-1029) from '' Schistocerca gregaria'' in

Eritrea Eritrea, officially the State of Eritrea, is a country in the Horn of Africa region of East Africa, with its capital and largest city being Asmara. It is bordered by Ethiopia in the Eritrea–Ethiopia border, south, Sudan in the west, and Dj ...

* A.C. Rath's isolate F506 (= ARSEF 4556; DAT 506; IMI 384583) from '' Boophilus'' sp. (

Acari Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as ea ...

: Ixodidae) in USA (Florida) * ''M. anisopliae'' isolated from ''

Dermolepida albohirtum ''Dermolepida albohirtum'', the cane beetle, is a native Australian beetle and a pest of sugarcane. Adult beetles eat the leaves of sugarcane, but greater damage is done by their larvae hatching underground and eating the roots, which either ki ...

'' (Coleoptera:

Scarabaeidae The family Scarabaeidae, as currently defined, consists of over 35,000 species of beetles worldwide; they are often called scarabs or scarab beetles. The classification of this family has undergone significant change. Several groups formerly tre ...

) include: CSIRO FI-1358 (= ARSEF 7493) and FI 1045 which is the active ingredient of 'Biocane'.

References

External links