Briefly describe the role of biological control agents, to control pests and diseases.

Explanation

Biocontrol is defined as controlling plant diseases and pests using biological methods, earlier chemicals like insecticides and pesticides were used for biocontrol.
Some examples of Biocontrol are :
i. Lady birds and dragon flies are used to get rid of aphids and mosquitoes.
ii. The bacteria Bacillus thuringiensis (BT) are used to control butterfly caterpillars.
a. Dried spores of BT are mixed with water and sprayed on plants such as brassicas and fruit trees.
b. Insect larvae, after eating these are killed by the toxin released in their gut.
c. B.Thuringiensis toxin genes have been introduced into plants to provide resistance to pests for eg : Bt. Cotton.
iii. Trichoderma sps. free living fungi are present in root systems where they act against several plant pathogen.
iv. Baculoviruses are pathogens that attack insects and other arthropods.
a. Most of these biocontrol agents belong to the genus Nucleopolyhedrovirus. These are species-specific narrow spectrum insecticides.
b. They do not harm plants, mammals, fish and other non-target insects.
c. Baculoviruses are helpful in integrated pest management programme, in which beneficial insects are conserved.