Question

Pest resistance in crop plants may be due to:
I. Physiological characteristics
II. Biochemical characteristics
III. Morphological characteristics

• A. I only
• B. I and II only
• C. I and III only
• D. I, II and III

Answer 1

The correct option is D I, II and III

Agricultural pests are organisms that attack agricultural crops and destroy them, leading to huge crop losses. Some crop plants naturally develop resistance to pests as a result of morphological, physiological or biochemical characteristics in them.

Some examples are listed below:

• Presence of hairy leaves provides resistance to jassids (sap-sucking insects) in cotton and cereal leaf beetles in wheat. Wheat varieties with strong solid stems are not preferred by stem sawfly (insect). These are morphological adaptations that provides pest resistance.
• Nectar is a sweet sugary fluid secreted by special glands called nectaries present in the plant. Nectar often attracts insects towards the plant as the insects feed on it. Nectar-less varieties of cotton do not attract bollworms, a common pest that infests cotton plants. This is a physiological adaptation that provides pest resistance.
• In maize crop certain biochemical characteristics like low nitrogen, low sugar and high aspartic acid content helps resist against maize stem borers.