Within the genus Bacillus, three species, thuringiensis, cereus, and anthracis, are closely related. B. anthracis, causes anthrax; B. cereus, causes food poisoning. In 1906, G.F. White first described the bacteria which caused American foulbrood, and named it Bacillus larvae. In 1993, both B. larvae and B. pulvifaciens were transferred to a new genus, Paenibacillus
In the late 1920s and early 1930s, several reports examined the effectiveness of B. thuringiensis against the corn borer, Pyrausta nubilalis, and a number of other lepidopteran pests.
The insect pathogen B. thuringiensis has a highly selective mode of action. In most cases, the activity of an isolate of B. thuringiensisis limited to a single order of insects; insecticides formulated with B. thuringiensis are not harmful to predatory insects or to other animals, including man. Insecticides formulated with B. thuringiensis have several advantages that should have led to widespread use for the control of insects. These include:
Because of the insect specificity, these insecticides would not harm beneficial insects and would therefore fit well into integrated pest management programs
Agents formulated with B. thuringiensis are nonharmful to mammals, including man; food products that are treated with these insecticides would be safe for the consumer. Furthermore, because insecticides formulated with B. thuringiensis have no requirement for a preharvest cutoff, they can by sprayed immediately before harvest
Because the crystal toxin does not become soluble except under very alkaline conditions, these agents usually remain in an alert state and are not phytotoxic
The crystal toxin of B. thuringiensis subsp. kurstaki is a natural product that can be degraded in the soil and under certain other environmental conditions; it will not build up in the soil, ground water, or other places in the environment.
Despite these advantages, acceptance of insecticides formulated with B. thuringiensis has been disappointing, primarily because they have not proven as effective under field conditions as laboratory tests have predicted.
multiple sources
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