Question

The protein products of the genes cryIAc and cryIIAb in Bacillus thuringiensis are responsible for controlling which of the given insects?
1.Bollworm
2.Corn borer

• A. 1 only
• B. 2 only
• C. 1 and 2
• D. None of the above

Answer 1

The correct option is A 1 only

Substances of biological origin, i.e, obtained from plants, animals or microbes, that are used to kill pests are known as biopesticides. Bacillus thuringiensis is a soil bacterium which is widely used as a biopesticide in the field of agriculture. Often, spores of B. thuringiensis are spread over crops to kill lepidopteran insect pests.

The cry genes, present in B. thuringiensis, code for a crystalline protoxin (inactive toxin) protein or Cry protein, commonly known as Bt toxin. The protoxin remains inactive upon ingestion of the spores by the insects, and the alkaline medium of the insect gut activates the protoxin.

The active toxin binds to the epithelial cells of the midgut of the insects and creates pores in the gut wall. The insect stops eating at this point and eventually dies due to starvation.

The protein encoded by the genes cryIAc and cryIIAb control the cotton bollworms. The corn borers are controlled by the toxin proteins coded by the gene cryIAb.