Metarhizium

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.

Species
Before molecular techniques were introduced at the end of the 20th century, Metarhizium species were identified on morphological (notably conidial) characteristics. The 'original' species included: M. anisopliae (with M.a. var. major), M. brunneum, M. cicadinum, M. cylindrosporum, M. flavoviride, M. taii, M. truncatum, and M. viridicolumnare. In 2009, nine former varieties of the type species M. anisopliae were assigned species status. New species have continued to be identified, with original names sometimes re-instated (notably M. brunneum). The first complete chromosome length genome sequence for any Metarhizium was carried-out for this species at Swansea University in 2021.

The index fungorum currently (April 2024) lists:
 * 1) Metarhizium acridum
 * 2) Metarhizium alvesii
 * 3) Metarhizium anisopliae
 * 4) Metarhizium argentinense
 * 5) Metarhizium atrovirens
 * 6) Metarhizium baoshanense
 * 7) Metarhizium bibionidarum
 * 8) Metarhizium biotecense
 * 9) Metarhizium blattodeae
 * 10) Metarhizium brachyspermum
 * 11) Metarhizium brasiliense
 * 12) Metarhizium brittlebankisoides
 * 13) Metarhizium brunneum
 * 14) Metarhizium campsosterni
 * 15) Metarhizium candelabrum
 * 16) Metarhizium cercopidarum
 * 17) Metarhizium chaiyaphumense
 * 18) Metarhizium cicadae
 * 19) Metarhizium cicadinum
 * 20) Metarhizium clavatum
 * 21) Metarhizium culicidarum
 * 22) Metarhizium cylindrosporum
 * 23) Metarhizium dendrolimi
 * 24) Metarhizium eburneum
 * 25) Metarhizium ellipsoideum
 * 26) Metarhizium flavoviride
 * 27) Metarhizium flavum
 * 28) Metarhizium frigidum
 * 29) Metarhizium fusoideum
 * 30) Metarhizium gaoligongense
 * 31) Metarhizium globosum
 * 32) Metarhizium granulomatis
 * 33) Metarhizium gryllidicola
 * 34) Metarhizium guniujiangense
 * 35) Metarhizium huainamdangense
 * 36) Metarhizium humberi
 * 37) Metarhizium indigoticum
 * 38) Metarhizium kalasinense
 * 39) Metarhizium koreanum
 * 40) Metarhizium lepidiotae
 * 41) Metarhizium lepidopterorum
 * 42) Metarhizium macrosemiae
 * 43) Metarhizium majus
 * 44) Metarhizium megapomponiae
 * 45) Metarhizium minus
 * 46) Metarhizium niveum
 * 47) Metarhizium nornnoi
 * 48) Metarhizium novozealandicum
 * 49) Metarhizium ovoidosporum
 * 50) Metarhizium owariense
 * 51) Metarhizium pemphigi
 * 52) Metarhizium phasmatodeae
 * 53) Metarhizium phuwiangense
 * 54) Metarhizium prachinense
 * 55) Metarhizium pseudoatrovirens
 * 56) Metarhizium purpureogenum
 * 57) Metarhizium purpureonigrum
 * 58) Metarhizium purpureum
 * 59) Metarhizium putuoense
 * 60) Metarhizium reniforme
 * 61) Metarhizium rileyi
 * 62) Metarhizium robertsii
 * 63) Metarhizium rongjiangense
 * 64) Metarhizium samlanense
 * 65) Metarhizium sulphureum
 * 66) Metarhizium synnematis
 * 67) Metarhizium taii
 * 68) Metarhizium takense
 * 69) Metarhizium truncatum
 * 70) Metarhizium viride
 * 71) Metarhizium viridicolumnare
 * 72) Metarhizium viridulum

Other Reclassified Species Names

 * M. glutinosum is now placed in the Stachybotryaceae as Albifimbria (Myrothecium) verrucaria (Alb. & Schwein.) L. Lombard & Crous
 * species now placed in other genera in the Clavicipitaceae include:
 * M. album Petch, 1931 and other names now assigned to M. anisopliae (see synonyms)
 * M. aciculare is now Keithomyces acicularis
 * M. carneum is now Keithomyces carneus
 * M. khaoyaiense is now Purpureomyces khaoyaiensis
 * M. kusanagiense is now Yosiokobayasia kusanagiensis
 * M. marquandii is now Marquandomyces marquandii
 * M. martiale is now Nigelia martialis
 * M. yongmunense is now Sungia yongmunensis

Teleomorphs
The teleomorphs of Metarhizium species appear to be members of the genus Metacordyceps. Metacordyceps taii (as Cordyceps taii) has been described as the teleomorph of Metarhizium taii: a name that has now been restored.

Whether the other varieties of M. anisopliae have their own teleomorphs is not yet clear. Some, if not most, strains of M. anisopliae possibly have lost the capability of reproducing sexually.

Natural pesticide
The artificially grown fungi's spores are also used as a natural pesticide. Certain strains are advised against use in food-growing fields and in close proximity to water sources due to risk of their contamination.

Locust control
In the 1990s, the LUBILOSA research programme proved that M. acridum in its spore form was effective in killing locusts and other members of the Acrididea families with no deleterious effects found in field trials on any nontarget species except for the domesticated silk worm Bombyx mori. It is currently produced as a biopesticide under the name Novacrid by the company Eléphant Vert in their factory in Meknès, Morocco. The same company recently (2019) obtained the licence to produce and market the original product developed by LUBILOSA, which is called Green Muscle. A third product, Green Guard, is produced by BASF of Australia for the control of Australian plague locusts and wingless grasshoppers.