Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.

Explanation

### Step-by-Step Solution:

1. **Introduction to Bt Cotton**:
- Bt cotton is a genetically modified organism (GMO) that has been engineered to express a specific gene from the bacterium *Bacillus thuringiensis* (Bt). This gene is often referred to as the cry gene.

2. **Function of the Cry Gene**:
- The cry gene encodes for a protein crystal that possesses insecticidal properties specifically targeting certain insect groups, particularly the Lepidoptera (which includes moths and butterflies).

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