Horticulture/Beauveria bassiana

Beauveria bassiana is a fungus that grows naturally in soils throughout the world and causes disease in various insects by acting as a parasite; 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. The species is named after the Italian entomologist Agostino Bassi who discovered it in 1835 as the cause of the muscardine disease of silkworms. Beauveria bassiana (formerly also known as Tritirachium shiotae) is the anamorph (the asexually reproducing form) of the fungus species Cordyceps bassiana. The teleomorph (the sexually reproducing form) was discovered in 2001.

The disease caused by the fungus is called white muscardine disease. When spores of the fungus come into contact with the body of an insect host, they germinate, enter the body, and grow inside, eventually killing the insect. Afterwards a white mold grows on the cadaver and produces new spores. Most insects living near the soil have evolved natural defenses against the fungus, but many other insects are susceptible.

Mode of Action
As an alternative to chemical insecticide, enter the pathogenic fungi, Beauveria bassiana. It gives us a natural mans to fight pests.

Firstly, beauveria bassiana fungus spores land on the bugs. With high humidity, spores germinate. Secondly from there, they enter the pest’s cuticle. Thirdly, inside the host, the fungus multiplies rapidly. This rapid multiplication of fungus leads to the release of toxic chemicals. Finally, this makes the host body devoid of nutrients. Eventually resulting in the death of the host.

Unlike other bacterias and viruses of insects, Beauveria bassiana infects the host only on contact. There is no need for its consumption. The infection spreads just by physical contact. 

Uses
The fungus does not appear to infect humans or other animals and is considered safe as an insecticide but the spores might cause a problem to people with breathing difficulties. The microscopic spores are typically sprayed on affected areas; the plan for malaria control is to coat mosquito nets with them.

Target species
Beauveria bassiana parasitizes a very wide range of arthropod hosts, and so should be considered a nonselective pesticide. It should not be applied to flowers visited by pollinating insects.

Known targets include:


 * ../Aphids/
 * ../Whiteflies/
 * ../Bugs/
 * Lygus bugs
 * Chinch bug


 * ../Mealybugs/
 * ../Psyllids/
 * ../Grasshoppers/
 * ../Thrips/
 * ../Termites/
 * Fire ants
 * Flies
 * Fungal gnats
 * Shoreflies
 * Mosquitoes


 * ../Beetles/
 * Colorado potato beetle
 * Mexican bean beetle
 * Japanese beetle
 * Boll weevil
 * Cereal leaf beetle
 * Bark beetles
 * Black Vine Weevil
 * Strawberry root weevil


 * ../Caterpillars/
 * European corn borer
 * Codling moth
 * Douglas fir tussock moth


 * ../Mites/

Action
Beauveria bassiana rapidly colonizes the host organism, killing within a matter of days, depending on ambient temperatures. Best action is achieved during warm, humid weather.

Application
Primarily applied as an emulsified suspension (ES) or wettable powder (WP), though research is being done into using lures in order to limit exposure to non-target species.

Precautions
The low selectivity of this biocontrol is cause for great concern and caution when applying. It can affect beneficial insects (such as lady beetles), and can also affect the lungs and nasal passages of mammals, including humans, particularly in individuals with compromised immune systems, though the US EPA lists it as safe for human exposure, with "no expected health risks to humans."

Resistance
Soil dwelling arthropods generally have resistance, as the fungus is common in soils throughout the world.