Today it is used in insecticide sprays sold to home gardeners and others worldwide. In 1983, the World Health Organisation used Bt in West Africa to control disease-carrying blackflies. In the U.S., various strains of Bt are used to control spruce budworms and gypsy moths in forests, cabbage worms in broccoli and cauliflower, loopers or budworms in cotton and tobacco, and leaf rollers in fruits. As an ingredient of commercial sprays, Bt is relatively expensive and has some drawbacks. Although some pesticides kill on contact, Bt must be eaten by insects to be effective.
Sunlight breaks down Bt, and rain washes it from the plants.
Therefore, Bt must be applied exactly where and when the target insects are feeding and they must consume it quickly before it disappears. Bt and Biotechnology Today, plants can be genetically engineered to produce their own Bt. This hereditary information is contained in individual units or sections of DNA called genes. The genes that are passed from parent to offspring determine the traits that the offspring will have. In addition to using traditional breeding methods of improving plants and animals through years of cross-breeding and selection, scientists can now isolate the gene or genes for the traits they want in one animal or plant and move them into another.