Infection of silkworm larvae by the entomopathogenic fungus Metarhizium anisopliae

Abstract

The isolate E9 of Metarhizium anisopliae was used in commercial hybrids of Bombyx mori larvae to evaluate its biological effect. Symptomatological analyses showed typical signs of fungal infection. Histopathology revealed the presence of large numbers of hemocytes in the hemocoel, and on the sixth dpi the bodies of the insects appeared to be colonised by the fungus. The isolate E9 is pathogenic to larvae B. mori and; therefore, death of the insects was caused by the colonization of fungus in the epidermal and mesodermal tissues.

Direct Visualization of Fungal Burden in Filamentous Fungus-Infected Silkworms

“…Traditionally, studying fungal burden in infected silkworms was limited to the usage of transgenic fungal mutants expressing fluorescent proteins [ 19 , 23 ], or to the application of time-consuming histological staining procedures [ 24 , 25 ]. To circumvent these limitations, we established a simple staining protocol using a common fluorescent dye, CW, to stain the cell wall of fungal hyphae in freshly extracted organs of A. fumigatus -infected silkworms, as demonstrated in Figure 1 .…”

“…There, following the disease progression relied on recombinant fungal strains that express fluorescent proteins. In the case of detecting non-fluorescent fungal strains in silkworms, Grocott-Gomori’s methenamine silver stain and periodic acid-Schiff stain, both of which are time-consuming, have been employed for the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae , respectively [ 24 , 25 ].…”

“…Although silkworm infection models have been established for different fungal pathogens, microscopical visualization of fungal burden in silkworms so far relies on recombinant fungal strains that express fluorescent proteins [ 19 , 23 ] or on classical histological staining procedures such as Grocott-Gomori’s methenamine silver stain or periodic acid-Schiff stain in tissues, which are time-consuming due to fixation, sectioning, dehydration, and staining steps [ 24 , 25 ].…”

Isolation and identification of a fungal pathogen, Beauveria bassiana (Bals.-Criv.) Vuill. (Ascomycota: Hypocreales) from the Hatay yellow strain of silkworm, Bombyx mori L., 1758 (Lepidoptera: Bombycidae) in Türkiye

“…A study of commercial silkworm hybrids showed that a strain of Metarhizium anisopliae (Metschn.) Sorokīn (Ascomycota: Hypocreales) is an important pathogen of the silkworm (Ribeiro et al, 2017). Although governments and different organizations organize different programs and provide support to inform farmers and control these diseases, crop losses are not yet controlled as expected.…”

Propriedades biológicas e químicas de solos arenoso e argiloso tratados com isolados fúngicos sob soja e milho em casa-de-vegetação

“…Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) é um fungo entomopatogênico, amplamente utilizado na agricultura devido à capacidade de se adequar a ambientes heterogêneos. Essa espécie pode infectar uma diversa variedade de insetos devido principalmente à evolução de genes que provocam a degradação da cutícula do hospedeiro, desintoxicação e biossíntese de toxinas (DORIN et al, 2015;RIBEIRO et al, 2017). O fungo M. anisopliae ganhou atenção dos pesquisadores brasileiros ao ser notado sua ocorrência epizoótica sobre a espécie Mahanarva posticata (Stal) (Hemiptera: Cercopidae), conhecida popularmente como a cigarrinha da folha da cana-de-açúcar (OLIVEIRA et al, 2016).…”