Beauveria bassiana
(from Wikipaedia)
Beauveria bassiana is a fungus that grows naturally in soils throughout the world and acts as a parasite on various insect species, causing white muscardine disease; it thus belongs to the entomopathogenic fungi. It is being used as a biological insecticide to control a number of pests such as termites, whitefly, different beetles and its use in the control of the malaria-transmitting mosquitos is under investigation.
Discovery and name
The species is named after the Italian entomologist Agostino Bassi who discovered it in 1835 as the cause of the muscardine disease of domesticated silkworms. It was formerly also known as Tritirachium shiotae.
Relation to Cordyceps and other fungi
Beauveria bassiana is the anamorph (asexually reproducing form) of Cordyceps bassiana. The latter teleomorph (the sexually reproducing form) has been collected only in eastern Asia.
The name B. bassiana has long been used to describe a complex of morphologically similar and closely related species. Rehner and Buckley [3] have shown that B. bassiana consists of many distinct lineages that should be recognized as distinct phylogenetic species.
Morphology of the fungus
In culture, B. bassiana grows as a white mold. On most common cultural media, it produces many dry, powdery conidia in distinctive white spore balls. Each spore ball is composed of a cluster of conidiogenous cells. The conidiogenous cells of B. bassiana are short and ovoid, and terminate in a narrow apical extension called a rachis. The rachis elongates after each conidium is produced, resulting in a long zig-zag extension. The conidia are single-celled, haploid, and hydrophobic.
White muscardine disease
The insect disease caused by the fungus is called white muscardine disease. When the microscopic spores of the fungus come into contact with the body of an insect host, they germinate, penetrate the cuticle, and grow inside, killing the insect within a matter of days. Afterwards a white mold emerges from the cadaver and produces new spores. A typical isolate of B. bassiana can attack a broad range of insects; various isolates differ in their host range. The factors responsible for host susceptibility are not known.
Beauveria bassiana parasitizing the Colorado potato beetle has been reported to be, in turn, the host of a mycoparasitic fungus Syspastospora parasitica. This organism also attacks related insect-pathogenic species of the Clavicipitaceae.
Seen mainly on cicadas in the Sydney region
| Beauvaria bassiana | - Beauvaria bassiana - sugar icing fungus - in early stages of development on a cicada corpse, Towlers Bay walk, near West | |
