Bt toxin is responsible for killing which of the following insect groups?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → All of these
Some strains of Bacillus thuringiensis make protein crystals that contain an inactive toxin (protoxin). When an insect eats it, the alkaline pH of the insect gut turns it into the active toxin, which binds to the gut cells, makes pores and kills the insect. The book names three insect groups killed by these proteins.
Option (1) Lepidopterans (tobacco budworm, armyworm) — Correct statement, but it is only one of the correct points, so on its own it is not the answer. Lepidopterans, such as the tobacco budworm and armyworm, are killed by Bt proteins.
Option (2) Coleopterans (beetles) and dipterans (flies, mosquitoes) — Correct statement, but it is only one of the correct points, so on its own it is not the answer. Coleopterans (beetles) and dipterans (flies, mosquitoes) are also killed by Bt proteins.
Option (3) Dipterans (flies, mosquitoes) — Correct statement, but it is only one of the correct points, so on its own it is not the answer. Flies and mosquitoes are dipterans, and Bt proteins kill them as well.
NCERT Extract:
Biotechnological Applications in Agriculture – “… Bt Cotton: Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein.”