Question

a)Organic farmers prefer biological control of diseases and pest to the use of chemical for same purpose .Justify
b)Give an example of a bacterium , a fungus and an insect that are used as biocontrol agents.

Answer 1

Hint: Biological control is environmentally friendly and does not cause any kind of pollution of harmful organisms, while chemical control is limited to short-term control. Biological control preserves the ecosystem while chemical control is disrupting the ecosystem.

Complete answer:
a) Farmers prefer biocontrol to chemicals, because the use of chemicals could be toxic to both humans and animals. Chemical pesticides are synthetic products. They are broad in spectrum and affect a number of non-target organisms. Chemical pesticides also pollute the air, water and soil. Biopesticides, on the other hand, are live organisms or their natural products with pesticide properties.

They are pest-specific and harmless to other organisms. Biopesticides are non-polluting. Organic farmers therefore prefer the biological control of diseases and pests to the use of chemical pesticides.It's a non-polluting practise. It does not affect the relationship of natural predators and food chains.

Biological control is self-regulation and does not require any kind of management. While you have to manage a lot of things in the case of chemical control. For example, before deciding whether or not to spray, you have to select an appropriate pesticide or insecticide according to the target organisms and you have to decide on the time of spraying, etc.

Biological control is cost-free, while other control methods require some expenditure and management.


b) Biocontrol agents are part and parcel of organic farming. Farmers believe in mutualism in organic farming. In other words, organic farmers maintain a balance of beneficial and harmful agents within the system. Chemicals used to eradicate pests and parasites may not always be successful and may also harm useful agents. Farmers have instead used biocontrol agents that predate insects and pests that cause crop diseases. This approach to pest management needs vivid knowledge of the life cycle and feed habits of different life forms.
Bacterium : Bacillus thuringiensis
Fungus : Trichoderma
Insect : Ladybird and dragonflies.

Note: Biotechnology has been extensively extended and has developed a number of biocontrol agents. For example, Bacillus thuringiensis, often referred to as Bt, is a microbial biocontrol agent. Spraying a Bt solution made of spores on plants will kill the caterpillars of the butterfly. Spores that are ingested release and kill toxins in the guts of the larvae.