Question

Which one is infective stage of Rotylenchulus reniformis?
A. Preadult female
B. 2\textsuperscript{nd stage juvenile}
C. 3\textsuperscript{nd stage juvenile}
D. Adult males
Choose the correct answer from the options given below

• A. A only
• B. B only
• C. A and B only
• D. C and D only

Hint:

Unlike root-knot and cyst nematodes where the \(\text{J}_2\) is the infective stage, the infective stage of the reniform nematode (Rotylenchulus reniformis) is the immature, preadult female.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The reniform nematode, Rotylenchulus reniformis, is a semi-endoparasitic pest of crops such as cotton and pulses.
It undergoes a series of molts in the soil before invading the host plant root.

Step 2: Detailed Explanation:
The life cycle of Rotylenchulus reniformis differs from many other plant-parasitic nematodes:
1. Soil Phase: The first-stage juvenile (\(\text{J}_1\)) molts inside the egg to become a second-stage juvenile (\(\text{J}_2\)), which hatches.
The \(\text{J}_2\), \(\text{J}_3\), and \(\text{J}_4\) stages remain in the soil and do not feed.
2. Infective Stage: The final molt in the soil produces the immature, vermiform preadult female (young female).
This preadult female (A) is the infective stage.
It finds host roots, penetrates the cortex with its anterior end, and establishes a permanent feeding site in the pericycle.
Once established, the posterior portion of the female's body swells, assuming a characteristic kidney (reniform) shape, and begins producing eggs.
The other stages (\(\text{J}_2\) or \(\text{J}_3\)) and adult males do not infect host plants.

Step 3: Final Answer:
Therefore, the preadult female (A only) is the infective stage of Rotylenchulus reniformis.