When eaten by insects, delta endotoxins, that were produced by the bacteria in fermentation, are activated and result in death.
Although not yet commercially developed, patents have been issued for strains of B. thuringiensis which have activity against nematodes.
A second group of toxins produced by some B. thuringiensis strains is called B-exotoxin (or beta exotoxin). Although first tested against insects, because the mode of action is to interfere with RNA transcription, they have been found to have activity against many forms of life including nematodes. Again, these toxins have not been commercially developed for nematode management.
At the conclusion of the fermentation process, if the medium is centrifuged, the delta endotoxins are found in the centrifugate while B-exotoxins are found in the supernatant.