Question

What are the biocontrol agents? Mention any two groups of biocontrol agents and their hosts?

Answer 1

Hint: Increased use of pesticides has caused various types of problems like soil pollution, water pollution, eutrophication, biological magnification, etc. Biocontrol or biological control is done as a means of sustainable development.

Complete answer:
 Biocontrol is a method of controlling pests by the process of predation instead of depending on toxic chemicals. This allows us to remove the undesirable pest without disturbing the entire biodiversity of that ecosystem as more is the biodiversity better is the health of that ecosystem. The organisms employed to do biocontrol by the process of predation, parasitism, herbivory are known as biocontrol agents.
Two important groups of biocontrol agents are:
Trichoderma species: They are free-living fungi found in the root ecosystems. They are very effective against several pathogens such as rot causing bacteria, fungi, etc.
Baculoviruses: They are members of the genus Nucleopolyhedrovirus and attack insects and other arthropods. They are excellent candidates for species-specific narrow spectrum insecticidal applications.

Additional Information: The microbial method of biological control is by using the bacterium Bacillus thuringiensis. These bacteria are available in sachets in the form of spores which can be mixed with water and sprayed on susceptible plants like Brassica and fruit trees.
These bacteria produce a harmful toxin and kill the insect larva once they enter into its gut.
But they do not harm other insects. Thus, this is a sustainable method as desirable insects are not killed.

Note: Biocontrol is also done to prevent diseases. Gambusia fish are released in water bodies as they feed on mosquito larvae. This causes a reduction in the number of cases of mosquito-borne malaria disease.
Similarly, the vector of dengue Aedes aegypti is controlled by introducing turtles and copepods(small crustaceans) in ponds and wells.