Question

The most common bioinsecticide in present world for protection of cotton and mustard is
A. Pyrethrin
B. Bt
C. Rotenone
D. None of the above

Answer 1

Bt toxin, is a popularly known bio-pesticide. It is generated by a bacterium called Bacillus thuringiensis. Bt toxin gene has been cloned from this bacterium and communicated in plants. Bt toxin protein when ingested by the insect, due to the alkaline pH of the gut it gets converted to its active form. The activated toxin straps to the surface of midgut epithelial cells. Thus it creates pores which cause cell swelling and lysis and eventually kills the insect.

Complete answer:
Let's discuss the option and find the correct answer.
A. Pyrethrin : The pyrethrins are a category of organic compounds normally derived from pyrethrum that have potent insecticidal activity by targeting the nervous systems of insects.Pyrethrin is a kills a good scope of insect pests including ants, mosquitoes, moths, flies and fleas. Pyrethrin kills off insects almost instantly upon contact. Hence option A is incorrect.
B. Bt :Bt stands for Bacillus thuringiensis (Bt) a standard soil bacterium. Bt produces a protein that paralyzes the larvae of some harmful insects.Scientists have taken the Bt gene liable for the assembly of the insecticidal protein from the bacterium and incorporated it into the genome of plants.Insect-protected Bt crops provide the farmer with season-long protection against several damaging insect pests, and reduce or eliminate the necessity for insecticide sprays. This eliminates the yield loss that results from less than optimal pest control by applied farm insecticides.The most common Bio insecticide in present in the world for protection and mustard is Bt. Hence option B is correct.
C. Rotenone: Rotenone is a fragrance-free, colourless, crystalline ketonic compound . It is used as a broad-spectrum insecticide as well as pesticide. It occurs naturally within the seeds and stems of varied plants, just like the jicama vine plant and thus the roots of several members of Fabaceae. Hence option c is incorrect.
Hence option B: Bt is the correct answer.

Note: Biopesticide is a pesticide which is
(a) not chemical in nature
(b) more specific in action against the pest
(c) safer for the environment than chemical pesticides.