Question

Match List I with List II
List I (Compound):
A. Benzyl alcohol
B. Silica content
C. Asparagine content
D. Sinigrin content
List II (Target/Related insect-pests):
I. Brown plant hopper
II. Green bugs
III. Cabbage aphid
IV. Rice stem borer
Choose the correct answer from the options given below:

• A. A - II, B - I, C - IV, D - III
• B. A - IV, B - II, C - I, D - III
• C. A - II, B - IV, C - I, D - III
• D. A - II, B - IV, C - III, D - I

Hint:

Silica is well known for conferring mechanical resistance in grasses, especially in rice against the stem borer. Sinigrin is a hallmark glucosinolate of crucifers, directly linking it to crucifer-feeding pests like the cabbage aphid.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Host plant resistance to insect pests is mediated by morphological and biochemical factors.
Biochemical constituents can act either as feeding deterrents/barriers (conferring resistance) or as phagostimulants/attractants (conferring susceptibility).

Step 2: Detailed Explanation:
Let us analyze the chemical mediators of host-pest interactions:
A. Benzyl alcohol: Benzyl alcohol is a volatile compound found in barley and other small grains.
It has been shown to play a significant role in the resistance/susceptibility of cereals to greenbugs (Toxoptera graminum).
Therefore, A matches with II (Green bugs).
B. Silica content: Silicon accumulation in the epidermal cells of rice stems acts as a physical barrier.
High silica content interferes with the mandibles of the rice stem borer (Chilo suppressalis) larvae, preventing them from boring into the stem and feeding. This is a classic example of structural resistance.
Therefore, B matches with IV (Rice stem borer).
C. Asparagine content: Asparagine is an essential nitrogenous compound in rice sap.
High asparagine content acts as a major phagostimulant and nutritional requirement for the brown plant hopper (Nilaparvata lugens). Susceptible varieties often exhibit elevated levels of soluble asparagine.
Therefore, C matches with I (Brown plant hopper).
D. Sinigrin content: Sinigrin is a glucosinolate (mustard oil glycoside) found in cruciferous plants.
While toxic to many generalist herbivores, it acts as a specific attractant and feeding stimulant for specialist insect pests, such as the cabbage aphid (Brevicoryne brassicae).
Therefore, D matches with III (Cabbage aphid).

Step 3: Final Answer:
The matches are: A - II, B - IV, C - I, D - III, which corresponds to Option (C).