Land-Use Type Drives Soil Population Structures of the Entomopathogenic Fungal Genus Metarhizium

Abstract

Species of the fungal genus Metarhizium are globally distributed pathogens of arthropods, and a number of biological control products based on these fungi have been commercialized to control a variety of pest arthropods. In this study, we investigate the abundance and population structure of Metarhizium spp. in three land-use types—arable land, grassland, and forest—to provide detailed information on habitat selection and the factors that drive the occurrence and abundance of Metarhizium spp. in soil. At 10 sites of each land-use type, which are all part of the Swiss national soil-monitoring network (NABO), Metarhizium spp. were present at 8, 10, and 4 sites, respectively. On average, Metarhizium spp. were most abundant in grassland, followed by forest and then arable land; 349 Metarhizium isolates were collected from the 30 sites, and sequence analyses of the nuclear translation elongation factor 1α gene, as well as microsatellite-based genotyping, revealed the presence of 13 Metarhizium brunneum, 6 Metarhizium robertsii, and 3 Metarhizium guizhouense multilocus genotypes (MLGs). With 259 isolates, M. brunneum was the most abundant species, and significant differences were detected in population structures between forested and unforested sites. Among 15 environmental factors assessed, C:N ratio, basal respiration, total carbon, organic carbon, and bulk density significantly explained the variation among the M. brunneum populations. The information gained in this study will support the selection of best-adapted isolates as biological control agents and will provide additional criteria for the adaptation or development of new pest control strategies.

Biological Diabrotica Management and Monitoring of Metarhizium Diversity in Austrian Maize Fields Following Mass Application of the Entomopathogen Metarhizium brunneum

“…In addition, M. brunneum was only found in agricultural and open field sites when M. robertsii was also present [36]. In contrast, M. brunneum has been reported to be the dominant species in agricultural and grassland fields in Europe [12,37]. This could also be observed in our field sites in Tyrol, with more than 96.7% of all isolates being M. brunneum (without the applied strain).…”

“…For each MLG one isolate was selected to determine species allocation by sequencing the 5 end of nuclear translation elongation factor-1α (5 -TEF-1α) and subsequent sequence alignment with sequences of reference strains as described by Fernandez et al [12]. The 5 -TEF-1α was PCR amplified using alignment with reference sequences primers EF2F (5 -GGAGGACAAGACTCACAT-CAACG-3 ) and EFjmetaR (5 -TGCTCACGRGTCTGGC-CATCCTT-3 ).…”

“…Therefore, studies on diversity and distribution of soil inhabitants, especially Metarhizium, are requested and further knowledge is needed [9][10][11]. The Metarhizium community is influenced by changes in agricultural practice, e.g., abundance changes depending on the crop [10] as well as on type of land-use [12]. After application in high doses, biocontrol agents are exposed to resource restrictions and compete with the well-established indigenous microorganisms [5] including native Metarhizium strains.…”

Presencia natural de Metarhizium en suelos agrícolas de aguacate (Persea americana Mill.) en Colima, México

“…Este estudio es importante desde diferentes perspectivas; principalmente, para conocer las especies de HE que habitan de manera natural en un agroecosistema, aportar al conocimiento de la biodiversidad de microorganismos del suelo en un cultivo convencional de aguacate en el estado de Colima, y segundo, por la importancia económica que este grupo de organismos representa en la estrategia y desarrollo del control biológico de plagas en este cultivo. Los HE son importantes antagonistas de insectos plaga que habitan en el suelo (Uzman et al, 2019), y su presencia ha sido ampliamente estudiada en México en diversos cultivos como cítricos (Galán-Franco et al, 2011) Bravo et al, 2021). En Arkansas, EUA y utilizando como insecto trampa el ácaro Amblyomma americanum (Acarina: Ixodidae), lograron aislar e identificar molecularmente a las especies de M. robertsii y M. guizhouense (Goldsmith et al, 2021); lo que demuestra la capacidad de adaptación de estas dos especies a diferentes condiciones ambientales y hábitats.…”

Persistence of Metarhizium brunneum (Ascomycota: Hypocreales) in the Soil Is Affected by Formulation Type as Shown by Strain-Specific DNA Markers

“…Nevertheless, the levels of EAMb 09/01-Su several weeks after the last applications were about the same concentrations reported for Metarhizium spp. in other soils (e.g., [ 23 , 43 , 44 ]). Thus, the introduced EAMb 09/91-Su is able to establish itself in the soil, but it does not seem to behave as an invasive strain.…”