Beneficial Of The Month: Beauveris Bassiana
February 1, 2009 
Identification
Survival And Spread
In culture, B. bassiana grows as a white mold. 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.
Beneficial Activity
Unlike chemical insecticides, Beauvaria and other microbial insecticides can take longer to kill or debilitate the target pest. This may limit use to crops that can sustain some insect damage. To be effective, most microbial insecticides must be applied to the correct life stage of the pest, and some understanding of the target pest’s life cycle is required.
Good spray coverage is key, and it is important to begin treatments before high pest populations develop. Since it is a living product, Beauvaria should not be tank mixed with fungicides.
While considered relatively safe on beneficial insects, B. bassiana parasitizes a very wide range of arthropod hosts, and so should be considered a nonselective biological insecticide. Care should be used to avoid application to flowers visited by pollinating insects.
B. bassiana has been mass produced and is available in commercial formulations for use in standard spray equipment. It is sold commercially under the brand names Mycotrol O from BioWorks and Naturalis L. from Troy BioSciences. As an insecticide, the spores are sprayed on affected crops as an emulsified suspension or wettable powder. It is approved for use in organic crop production. The re-entry interval is four hours, and it has a zero pre-harvest interval.
The fungus rarely infects humans or other animals, so it is generally considered safe as an insecticide. However, it should be used with caution because, as with any powder, the spores may exacerbate breathing difficulties.