Q.Write a note on biocontrol agents.
Biocontrol agents are natural biological enemies — bacteria, fungi, viruses or protozoans — deployed against insect pests and weeds instead of chemical pesticides, working by causing disease, competing with, or killin...
Step 1. Define biocontrol. Biocontrol, or biological control, is the use of biological methods to control diseases and pests, by employing an organism's natural biological enemies against it, rather than relying on chemical insecticides and pesticides, which are harmful to human health and the environment.
Step 2. Explain how biocontrol agents act. They act in three ways: causing disease in the pest, competing with it, or killing it directly. Four broad groups serve as biocontrol agents — bacteria, fungi, viruses and protozoans.
Step 3. Give examples. Bacillus thuringiensis (Bt), sprayed as dried spores onto crops, is eaten by caterpillar larvae and releases a toxin (Cry protein) in their gut that kills them. Trichoderma species, rhizosphere fungi, suppress soil-borne fungal pathogens by producing inhibitory compounds like viridin and gliotoxin. Nucleopolyhedrovirus (NPV) and Granulovirus (GV) act as viral biocontrol agents against caterpillars and related pests, and the protozoan Nosema locustae controls grasshoppers and crickets. Microbes are also used as bioherbicides against weeds, such as the fungus Phytophthora palmivora against milkweed.
Biocontrol agents are microbes (e.g. Bacillus thuringiensis against caterpillars, Trichoderma against soil fungal pathogens) used as a safer, natural alternative to chemical pesticides.
Unlock everything free for 14 days
- Full step-by-step solutions
- Concept-first explanations
- Methods, shortcuts & mistakes
- PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.