Pests are the organisms that need host for survival. Pests are generally insects. They destroy crops by the following methods: Sucking the cellular sap from various plant parts
Cutting the roots, stem, and leaves of plants Boring into stems and fruits
Pests can be controlled by ploughing, crop rotation , spraying insecticides and using biological pesticides.
Biopesticides are better than chemical pesticides as they are biodegradable and less toxic. Biopesticides help in selective eradiacation of pests. Biological method of pest control requires knowledge of the life forms (predator + prey) that inhabit a particular area, their life cycles, and patterns of feeding and preferred habitats. Example Ladybirds and dragonflies are used to get rid of aphids and mosquitoes. Microbes can also act in the same manner. Bacillus thuringiensis (Bt) is used to control butterfly caterpillars.
