Nematodes, also called Aschelminthes or "roundworms", form a zoological group of species that share homogeneous anatomical and morphological characteristics, yet a diverse range of lifestyles.
Many live as parasites to other animals, particularly blood worms, hookworms and other types of Ascaris, which are enemies to humans and domestic animals. Others live in the soil. Some of them are phytophagous.
Simple, vermiform animals, their bodies roughly consist of an external tube (cuticle) that wraps around 2 internal superimposed tubes: the digestive tube and the genital tract (male or female).
Nematodes that are plant parasites have a perforating stylus on the front part of their digestive tube, followed by an oesophageal canal leading to a muscular bulb, a suction and discharge pump. Once the plant is perforated by the stylus, digestive enzymes produced by the salivary glands are injected through this pump which, then, sucks in the product of digestion and discharges it into the intestine.
Direct damage primarily results in weakening of the plant, and sometimes deformation, discolouration, gall, etc.; indirect damage includes aggravation of fungal illnesses and viruses.