ABSTRACT
Some plant-parasitic nematodes remain in the soil, feeding using the stylet to penetrate into the plant tissue. Nematodes with longer stylets can penetrate further into the root tissue. Such nematodes are termed ectoparasites, most of which retain their mobility and have the potential to vector viruses, for example Trichodorus spp. which transmit Tobacco Rattle Virus, causative agent of spraing symptoms in potatoes. Another group of plant-parasitic nematodes are the endoparasites, which invade the plant roots. Some of these retain their mobility, moving and feeding within the plant tissue sometimes leaving the roots and entering the foliage. In contrast to these mobile species, sedentary endoparasites will establish a specialised feeding site which will provide the nutrition they require to complete this phase of their life cycle. This level of parasitism is generally considered as more advanced as the nematode produces elicitors that induce the plant to produce a specialised feeding site, for example Globodera and Meloidogyne spp. Some nematodes have different life stages inside and outside of the plant, but all plant parasites have some life cycle stages adapted to survival or movement external to the plant.
