Question

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

Answer 1

Pesticides are substances that are used to hinder the growth of pests on the field. These are mainly made up of biological or chemical things that are present in our environment. They are used in the agricultural field to increase the productivity of crops.

Complete answer:
Biopesticides or also called biological pesticides are pest management interventions. They are made up of living things found in nature. They tend to pose fewer risks as compared to chemicals that are used to control pests. A very small quantity of it can be effective and thus they tend to break down more quickly, which means they cause less pollution. Some of these pesticides are targeted in their activity and they work for the removal of only some species. They are often most effectively used as part of an integrated pest management approach.

BT toxin is produced by a bacterium called Bacillus thuringiensis.BT toxin gene has been cloned from the bacteria and been expressed in plants to provide resistance to insects without the need for insecticides;in effect creating a bio-pesticide.

ACTION- Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans , coleopterans and dipterans .B thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. It is converted into an active form of a toxin due to the alkaline pH of the gut which solubilises the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis and eventually cause the death of the insect.

Note: Major growth areas for biopesticides are in the area of seed treatments and soil amendments. They are used to control internal seed-borne fungal pathogens as well as the fungal pathogens that are present on the surface of the seed. As they are not made synthetically by the chemicals, they do not pose ill-effects to the environment.