Insect resistance in host crop may be due to

Options

A. Physiological but not due to morphological character
B. Morphological, biochemical or physiological character
C. Biochemical but not due to morphological character
D. Morphological but not due to biochemical character

Answer

### Step-by-Step Solution:

1. **Understanding Insect Resistance**: Insect resistance in host crops refers to the ability of these plants to defend themselves against insect pests. This resistance can arise from various factors, including morphological, physiological, and biochemical characteristics.

2. **Morphological Factors**: Morphological factors include the physical structures of the plant that can deter insects. Examples include hairy leaves, which can prevent insect feeding, and the presence of trichomes or waxy substances that inhibit insect growth. These features serve as the first line of defense for the plant.

3. **Physiological Factors**: Physiological factors involve the internal processes of the plant that can affect insect resistance. For instance, in maize, an increase in aspartic acid (an amino acid) and lower nitrogen and sugar content can enhance resistance to pests like the stem borer. This indicates that the plant's physiological state can play a crucial role in its ability to resist insect attacks.

4. **Biochemical Factors**: Biochemical factors involve the production of specific chemicals by the plant that can deter or harm insects. For example, plants may produce proteinase inhibitors that disrupt protein digestion in insects when they feed on the plant. Other biochemical compounds can have direct toxic effects on insects, further contributing to the plant's resistance.

5. **Evaluating the Options**: Given the explanations above, we can evaluate the provided options:
- **Physiological but not due to morphological character**: Incorrect, as morphological factors are crucial.
- **Morphological, biochemical, or physiological character**: Correct, as all three factors contribute to insect resistance.
- **Biochemical but not due to morphological character**: Incorrect, as morphological factors are essential.
- **Morphological but not due to biochemical character**: Incorrect, as biochemical factors also play a role.

6. **Conclusion**: The correct answer is that insect resistance in host crops may be due to morphological, biochemical, and physiological factors.