What is meant by the term bio-pesticide? Name and explain the mode of action of a popular bio-pesticide.
A biological agent, which works as a pesticide, is called biopesticide. Biopesticides can be of following types:
(a) Microbial: Many Bacteria and fungi have pesticidal properties.
(b) Herbal: Some plants; like neem and canola can help in controlling pesticides.
(c) Plant Incorporated Protectants: These are incorporated into the genes of a plant through genetic engineering. Bt cotton is an example of a plant with the incorporated pesticidal property.
Bacillus thuringiensis affects the pests of Lepidoptera, Coleoptera and Diptera. It is a well-known example of microbial pesticide. A gene in B. thuringiensis produces a toxin, which remains inactive in the bacterium. Once this toxin enters the gut of the pest; the Alkaline pH makes it active. The toxin results in perforations in the gut of the pest, and eventually, the pest is killed. This gene has been incorporated in Bt cotton, Bt tomato, Bt brinjal, etc. These GM crops are giving good results.