(a) Organic farmers prefer biological control of diseases and pests to the use of chemicals for the same purpose. Justify.

(b) Give an example of a bacterium, a fungus and an insect that are used as bio control agents.

Organic farming is an integrated farming method of crop and livestock production that aims at reducing the use of pesticides, fertilizers, genetically modified organisms, antibiotics and growth hormones. It strives for sustainability and enhancement of soil fertility and biological diversity.

(a) Organic farmers develop a smart system where pests are not completely eradicated, rather kept at manageable levels by relying on biological control method. These farmers believe that complete eradication of the pests is undesirable because a number of beneficial predatory organisms depend on them for their survival. They seek to understand the interaction between different organisms. Conventional farming practices use chemical methods to kill both useful and harmful life forms indiscriminately. Thus, the use of biocontrol measures greatly reduces the use of toxic chemicals and pesticides. Moreover, humans are consuming these toxic chemicals along with their food, which can be fatal.

(b) Biocontrol refers to the use of biological methods for controlling plant diseases and pests. This method relies on natural predation.

Bacterium – Bacillus thuringiensis (Bt) is a bacterial Biocontrol agents that is used to control caterpillars of butterflies. The dried spores of Bt are mixed with water and sprayed onto the plants. This toxin attacks the larval gut and kills them.

Fungus – Trichoderma, a free-living fungus is used as a Biocontrol agent against numerous plant pathogens.

Insect – Dragonflies are used to get rid of mosquitoes. A beetle, ladybird is used to control aphids.