Bacteria-based bioinsecticides

One of the most widely used bioinsecticides is a naturally occurring soil bacterium called Bacillus thuringiensis or Bt. Bt produces a protein which is poisonous to insects. Often within 15 minutes of being eaten, the poisons begin to create ulcers in the insect’s stomach lining. The insect stops eating and eventually dies.

Researchers have identified between 500 and 600 strains, or types of Bacillus thuringiensis. Bt is very selective — it affects only a specific species of insect pest and does not harm humans, birds, fish, or beneficial insects. In 1983, a strain of Bt was used in West Africa to wipe out disease-carrying black flies.