Question

Match List I with List II
List I (Physical/biochemical traits of crop):
A. Hairy leaves
B. Saposin content
C. Sinigrin content
D. Solid stem
List II (Insect pests):
I. Cabbage aphid
II. Jassids
III. Stem sawfly
IV. Spotted alfalfa aphid
Choose the correct answer from the options given below:

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

Hint:

Remember:
- Leaf hairiness = Jassid resistance
- Solid stem in wheat = Stem sawfly resistance
- Sinigrin = Cabbage aphid feeding stimulant

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Host plant resistance to insect pests is mediated by morphological traits (physical barriers) or biochemical constituents (toxins, deterrents, or attractants).

Step 2: Detailed Explanation:
Let us analyze each crop trait and its relationship with the specific insect pest:
A. Hairy leaves (Trichomes): Leaf pubescence acts as a physical barrier.
In cotton, highly hairy leaves prevent jassids (Amrasca biguttula biguttula) from feeding on the leaf veins and laying eggs, conferring resistance.
Therefore, A matches with II (Jassids).
B. Saposin/Saponin content: Saponins are glycosidic secondary metabolites found in alfalfa (lucerne).
High saponin levels in the foliage act as a chemical defense, deterring feeding and reducing the survival of the spotted alfalfa aphid (Therioaphis maculata).
Therefore, B matches with IV (Spotted alfalfa aphid).
C. Sinigrin content: Sinigrin is a glucosinolate compound found in Brassicaceae crops.
While toxic to generalists, it acts as a host-selection cue and feeding stimulant for the specialist cabbage aphid (Brevicoryne brassicae).
Therefore, C matches with I (Cabbage aphid).
D. Solid stem: In wheat, a solid stem filled with pith (instead of being hollow) physically prevents the female wheat stem sawfly (Cephus cinctus) from laying eggs and prevents the larvae from boring through the stem.
Therefore, D matches with III (Stem sawfly).

Step 3: Final Answer:
Matching the traits to their pests yields: A - II, B - IV, C - I, D - III, which corresponds to Option (B).