Biological Methods in Crop Protection!

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Published in: September 2018

Agricultural production in India has seen significant growth, driven by the Green Revolution and its components, including high-yielding crop varieties, improved crop management, and synthetic fertilizers. However, to meet the increasing demands of a growing population, crop yields still need to be enhanced by reducing crop losses caused by diseases, pests, and weeds. Traditionally, chemical pesticides have been used to control these issues, but their toxic effects on the environment have led to a shift towards organic farming methods. In this context, biological methods play a crucial role in crop protection.

Pest Control through Biological Methods

Biological control involves the use of natural predators, parasitoids, and pathogens to manage pest populations.


Nature often provides a counterbalance for every pest species. In the case of insect pests, parasitoids are used. They are of two types: egg parasitoids and larval parasitoids.

  • Egg Parasitoids: These parasitoids attack and destroy the eggs of harmful pests. For example, Trichogramma is used to target the eggs of sugarcane borers and rice stem borers.
  • Larval Parasitoids: These parasitoids attack and kill the larvae of pests. Examples include Braconid and Bethylid wasps, which help control the black-headed caterpillar in coconut trees.


Predatory insects are larger and directly attack and consume harmful pests and larvae.

  • Example: Chrysopa, which preys on the cotton aphid. These predators are used at a rate of 20,000 eggs or larvae per hectare.


Viruses, bacteria, and fungi are used to induce diseases in pests, leading to their control.

  • Viruses: NPV (Nuclear Polyhedrosis Virus) at a concentration of 3×10^12 polyhedra per hectare controls the green bollworm in cotton.
  • Bacteria: Bacillus thuringiensis (Bt) is used to control the green bollworm, pink bollworm, and castor semilooper.
  • Fungi: Entomopathogenic fungi grow on pests and kill them. This method is effective against the coffee green scale insect, rhinoceros beetle in coconut, and sugarcane pyrilla.

Benefits of Biological Control

Using biological methods to control pests can lead to high returns with low costs. These methods are environmentally friendly and sustainable, making them ideal for organic farming practices.

By adopting these biological control methods, farmers can improve crop yields, reduce pest damage, and maintain environmental health.

Dr. M. Sugandhi, Dr. Ilango, Dr. H. Gopi, Postgraduate Research Centre, Livestock Sciences, Kattupakkam, Kanchipuram – 603 203.


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