| Metarhizium acridum | |
|---|---|
 | |
| Red locust with sporulating standard isolate ofM. acridum | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Sordariomycetes |
| Order: | Hypocreales |
| Family: | Clavicipitaceae |
| Genus: | Metarhizium |
| Species: | M. acridum |
| Binomial name | |
| Metarhizium acridum (Driver & Milner) J.F. Bisch., Rehner & Humber (2009) | |
| Synonyms | |
Metarhizium anisopliae var.acridumDriver & Milner | |
Metarhizium acridum[1] is the new name given to a group of fungalisolates that are known to be virulent and specific to theAcrididea (grasshoppers). Previously, thisspecies has hadvariety status inMetarhizium anisopliae (var.acridum[2]); before that, reference had been made toM. flavoviride orMetarhizium sp.[3] describing an "apparently homologous and distinctive group" of isolates that were mostvirulent againstSchistocerca gregaria (desert locust) in early screeningbioassays.
M. acridum almost exclusively infectsgrasshoppers (orderOrthoptera): researchers believe that this has to do with theMest1 gene which is not present inM. acridum. By taking a strain ofM. robertsii that has a nonfunctioningMest1 gene, researchers found that the mutant was only able to infectMelanoplus femurrubrum, which is consistent withM. acridum activity. This allows the initiation of the infection process on the specific targets. The expression of Mest1 in theentomopathogenM. acridum is triggered by substances that are only found on the waxy coat of the grasshoppers, which explains why this pathogen specifically only targetsgrasshoppers and locusts.[4]
M. acridum has been used to controllocusts and other grasshopper pest species: originally by the internationalLUBILOSA programme (which developed the product Green Muscle). This team identified and addressed key technical challenges for exploitation of microbial control agents, including isolate selection, mass production, and delivery systems (formulation andapplication).[5][6] Insect control (mortality) depends on factors such as the number of spores applied against the insect host, the formulation[7] and weather conditions.[8] Oil-based formulations allow the application of fungal spores under dry conditions, and are compatible with existingultra-low volume (ULV) application techniques for locust control.
As of 2012,M. acridum was under consideration by the USDA for release in the Western U.S. for control of native grasshoppers and crickets.[9]
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Zhang, L; Lecoq, M. (2021).Nosema locustae (Protozoa, Microsporidia), a biological agent for locust and grasshopper control.Agronomy 11, 711.DOI:10.3390/agronomy11040711