Question

White earhead in rice is due to attack of

• A. Leaf folder
• B. Yellow stem borer
• C. Swarming caterpillar
• D. Case worm

Hint:

Remember the classic stem borer symptoms:
Vegetative Stage $\rightarrow$ "Dead heart".
Reproductive Stage $\rightarrow$ "White earhead".

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Pest attack at different crop growth stages produces characteristic damage symptoms, which serve as diagnostic keys for field pest monitoring and management.

Step 2: Detailed Explanation:
Let us examine the damage symptoms of the given rice pests:
The Rice leaf folder (Cnaphalocrocis medinalis) folds the leaves longitudinally and scrapes the green chlorophyll, creating white paper-like leaf streaks.
The Swarming caterpillar (Spodoptera mauritia) acts as a defoliator, eating the leaves voraciously, leaving the field looking as if grazed by cattle.
The Rice case worm (Nymphula depunctalis) cuts leaf blades to construct tubular cases and defoliates the plants.
The Yellow stem borer, Scirpophaga incertulas (Lepidoptera: Crambidae), is the most destructive pest of rice in India.
The female lays eggs on leaf tips, and the hatched larva bores into the leaf sheath and enters the stem.
It feeds internally, cutting off the vascular connections.
When the attack occurs during the vegetative stage, the central leaf whorl dries up, producing a symptom known as "dead heart".
When the attack occurs during the reproductive stage (after panicle initiation), the panicle cannot receive nutrients.
This results in completely empty, chaffy panicles that turn white and stand erect instead of drooping. This symptom is known as "white earhead".

Step 3: Final Answer:
White earhead in rice is caused by the Yellow stem borer.