Beauveria

Species of Beauveria produce rather slow-growing white cottony colonies. Reproduction is copious and the conidia are easily detached, a condition often leading to scattered colonies when you thought you had carefully transferred only one. The one celled colourless conidia are borne along a thin filament that elongates in a zig-zag fashion as the conidia are produced. The conidia are produced on short spikes or denticles, giving the conidiogenous cells a spiny appearance. Species of Tritirachium are similar to some Beauveria species in having zig-zag conidiogenous cells, but differ in lacking denticles on their conidiogenous cells and in producing yellow brown to purple colonies. Beauveria species are commonly found associated with insects or habitats supporting insects. They commonly occur in private dwellings, where they probably decompose the dead bodies of insects, spiders and mites. They may also attack living insects and cause small epidemics. Beauveria bassiana (upper illustration), the best-known member of its genus, has been investigated widely as a potential agent for the biological control of harmful insects. Beauveria alba (lower illustration) commonly occurs in indoor environments and appears to be less strongly associated with insects than B. bassiana. Ref.: Hoog, 1972.