Question

Name the insect that attacks cotton crops and causes lot of damage to the crop. How has Bt cotton plants overcome this problem and saved the crop? Explain.

Answer 1

• The larvae that attack cotton crops are known as cotton bollworms.
• Bacillus thuringiensis’ active Cry gene is present in Bt cotton plants, which are genetically modified organisms that produce protein crystals at a specific stage of development. A poisonous insecticidal protein is present in these crystals. These proteins exist as inactive prototoxins, but when the pH in an insect’s gut becomes alkaline, they transform into active toxins.
• By attaching itself to the surface of midgut epithelial cells, the active toxin forms holes that lead to cell lysis and swelling, which ultimately results in the insect’s death.
• Genes for specific Bt toxins were identified from genetically transferred to a number of crop plants, including cotton, by B. thuringiensis.
• Most Bt poisons are specific to certain insect groups. A gene called cry codes for the toxin.