ABSTRACT

Introduction Nematodes are invertebrates, roundworms that occur in enormous numbers in all possible types of habitats, including soil, fresh water, seas, oceans as well as in the animal system. They belong to phylum Nematoda, and are free-living bacteriophagous, myceophagous or predaceous, or parasites of plants and animals, including both vertebrates and invertebrates. These microscopic organisms occur in millions in one square metre area of soil. Approximately, 3% of the expected nemic in biodiversity have been identified. Nematodes cause damage directly or indirectly to our food and fibre production and ultimately affect the quality of life. Feeding on plant cells by nematodes may deprive the host of nutrients and water for its growth. The conducting tissues responsible for the translocation of nutrients and water are often blocked. The association of plant parasitic nematodes with fungi or bacteria in disease complexes often increase the severity of the incidence. It also acts as a vector for transmission of soil-borne viruses. There are some beneficial roles played by the nematodes, including nutrient cycling and mineralization indicator of soil health and quality, and biocontrol agent of insect pests.