Pest Resistant Crops

The “Bt concept” – pest resistant transgenic plants

Bacillus thuringiensis, or Bt, is a bacterium that has attracted much attention for its use in pest control. The soil bacterium produces a protein that is toxic to various herbivorous insects. The protein, known asBt toxin, is produced in an inactive, crystalline form.

When consumed by insects, the protein is converted to its active, toxic form (delta endotoxin), which in turn destroys the gut of the insect. Bt preparations are commonly used in organic agriculture to control insects, as Bt toxin occurs naturally and is completely safe for humans.

More than 100 different variations of Bt toxin have been identified in diverse strains of Bacillus thuringiensis. The different variations have different target insect specificity. For example, the toxins classified under Cry1a group target Lepidoptera (butterflies), while toxins in the Cry3 group are effective against beetles.

Researchers have used genetic engineering to take the bacterial genes needed to produce Bt toxins and introduce them into plants. If plants produce Bt toxin on their own, they can defend themselves against specific types of insects. This means farmers no longer have to use chemical insecticides to control certain insect problems.