question_answer 67)

  What is meant by the term biopestidde? Name and explain the mode of action of a popular biopestidde.

Answer:

                  Biopestidde is a pesticide which is (i) Not chemical in nature. (ii) More specific in action against the pest. (iii) Safer for environment than chemical pesticides. A popularly known bio-pesticide is Bt toxin, which is produced by a bacterium called Bacillus thuringiensis. Bt toxin gene has been cloned from this bacterium and expressed in plants.Br toxin protein when ingested by the insect, gets converted to its active form due to the alkaline pH of the gut. The activated toxin binds to the surface of mid gut epithelial cells and create pores that causes swelling and lysis of the cell and eventually kills the insect.