Question

Given below are two statements:
Statement (I): Crop Rotation exerts most effect on pests having a narrow plant host range and limited mobility
Statement (II): Crop Rotation exerts most effect on pests having a wide plant host range and limited mobility
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement (I) and Statement (II) are correct
• B. Both Statement (I) and Statement (II) are incorrect
• C. Statement (I) is correct but Statement (II) is incorrect
• D. Statement (I) is incorrect but Statement (II) is correct

Hint:

For crop rotation to be an effective management strategy, the target pest must have: 1. High host specificity (a narrow host range).
2. A low capacity for dispersal (limited mobility).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Crop rotation is a cultural management practice where different crops are grown in a planned sequence on the same land.
Its effectiveness against a given pest species is determined by the pest's host specificity and its ability to migrate in search of host plants.
Detailed Explanation:
- Analysis of Statement (I): If a pest has a narrow host range, it depends on a specific crop for survival.
If the pest also has limited mobility, it cannot easily migrate to adjacent fields to locate its host.
Replacing its preferred host crop with a non-host crop through rotation deprives the pest of food, reducing its population.
Thus, Statement (I) is correct.
- Analysis of Statement (II): If a pest has a wide host range, it is a generalist and can survive on alternative crops introduced in the rotation.
Even if its mobility is limited, the pest will continue to feed and reproduce, making the rotation ineffective.
Thus, Statement (II) is incorrect.

Step 2: Final Answer:
Statement (I) is correct but Statement (II) is incorrect, which corresponds to option (3).