Question

Given below are two statements:
Statement (I): Propagative viruses cannot multiply in their respective vectors.
Statement (II): Non persistant viruses are generally stylet born.
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:

Remember the terminology: - Propagative = Multiplies within the insect vector.
- Stylet-borne = Carried externally on the feeding tube (non-persistent).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Plant viruses are classified into categories (non-persistent, semi-persistent, and persistent) based on how they interact with and are transmitted by their insect vectors.
Detailed Explanation:
- Analysis of Statement (I): Persistent plant viruses are further divided into circulative (non-propagative) and circulative-propagative viruses.
Propagative viruses enter the vector's body, cross the gut wall, and actively replicate (multiply) within the vector's tissues (such as the salivary glands and hemolymph) before transmission.
Therefore, stating that propagative viruses cannot multiply in their vectors is incorrect.
- Analysis of Statement (II): Non-persistent viruses are carried externally on the cuticular lining of the insect's mouthparts (specifically the stylet tip).
They are acquired and transmitted within seconds or minutes of feeding without entering the insect's body, and are commonly referred to as stylet-borne viruses.
Therefore, Statement (II) is correct.

Step 2: Final Answer:
Statement (I) is incorrect but Statement (II) is correct, corresponding to option (4).