Topic: Cry Gene-Crop-Pest Associations — NEET's Most Tested Table
| Parameter | Bt Cotton | Bt Corn |
|---|---|---|
| Cry gene(s) | cry1Ac + cry2Ab (two genes) | cry1Ab (one gene) |
| Product name | Bollgard-I (cry1Ac) / Bollgard-II (cry1Ac + cry2Ab) | various |
| Target pest | Cotton bollworm (Helicoverpa armigera) | European corn borer (Ostrinia nubilalis) |
| Pest taxonomic order | Lepidoptera | Lepidoptera |
| Pest life stage targeted | Larva | Larva |
| India approval year | 2002 (first developing country to approve Bt crop) | Not major Indian crop |
| Mode of exposure | Larva ingests leaf/boll tissue containing Cry protein | Larva ingests pollen and leaf tissue |
| Resistance strategy | Dual gene (cry1Ac + cry2Ab) slows resistance evolution | Single gene — higher resistance risk |
Memory Device — "1AC-2AB = Cotton; 1AB = Corn":
- cry1Ac + cry2Ab → Cotton (C for Complex — two genes; C for Cotton)
- cry1Ab → Corn (b for Borer; one gene; C for Corn)
NEET Trap: cry1Ab is Bt CORN. Students often write it for cotton. Remember: cotton has BOTH c and b genes; corn has only b.