Question

Write the modes by which insects affect the crop yield.

Answer 1

Insects affect crop yields in both useful and harmful ways. Harmful insects attack the plants and are called insect pests. Insect pests are of the following types :

• Chewing insects: Insect pests of this category cut the roots, stem and leaves with the help of their chewing mouthparts. They chew and swallow the pieces of plant parts. E.g., grasshoppers, caterpillars, locusts etc.
• Sucking insects: These insects puncture the plant parts and suck the cell sap with the help of their needle-like hollow beaks. E.g., leafhoppers, aphids, bugs, etc.
• Internal feeders: These insects bore into stems and fruits. They live inside the plant parts and harm the crop yield. E.g., weevils, borers, etc.
  Every year Insect pests cause significant damage to the crops and thereby reduce productivity. Various methods like the use of chemical pesticides, natural insecticides like neem, nicotine etc. and various biological methods are employed to control the pest infestation and reduce the damage done by them. Useful insects are those which assist in pollination thus, ensure fruit formation and those which feed on harmful) insect pests. E.g., the ladybird beetle feeds on aphids thus controlling this pest.