Nematodes are defined as thread-like microscopic, colorless, unsegmented round worms found in almost all habitats especially in soil and water. Nematodes may be free-living, predacious and parasitic. Nematodes that are considered our friends include entomopathogenic nematodes, insect-parasitic nematodes, slug-parasitic and free-living nematodes. Nematodes are called free-living because they are not parasitic to either plants or animals, live freely in soil and can play an important role in nutrient cycling in the soil food web. These nematodes are currently used as bio-indicators of soil health because they have diverse feeding habits, some of them can survive harsh, polluted, or disturbed environments better than others, and some have short life cycles and can respond to environmental changes rapidly.
Nematodes are called insect-parasitic because they benefit for their development and reproduction at the insect host's expense. The best examples are the members of the family Mermithidae.
Nematodes are called slug-parasitic because they benefit for their development and reproduction at the slug's expense. These nematodes nematodes are mutualistically associated a bacterial smbiont, which is capable of causing disease and killing several species of slugs. Example is Phasmarhabditis hermaphrodita, which belongs to a family Rhabditidae in the order of Rahbdita and symbiotically associated with a gram-negative bacterium, Moraxella osloensis .
Nematodes are called entomopathogenic because they are mutualistically associated with a species specific pathogenic bacterial symbiont, which are capable of causing disease in insect hosts. All the entomopathogenic nematodes are members of two families Steinernematidae and Heterorhabditidae in the order of Rhabdita.
In this blog, I will be providing the information on only entomopathogenic nematodes/insect-parasitic nematodes.