Agricultural cultivation encourages an increase in parasitic nematodes that feed on the crops being grown. Occasionally, new kinds of plant parasitic nematodes may be introduced into a field by contaminated plant parts, soil on farm equipment and irrigation water. Nematodes which parasitize plants may cause yield losses by themselves or they may join with other soilborne organisms such as viruses, fungi, and bacteria, to promote disease development in plants. Most often, nematode feeding reduces the flow of water and nutrients into the plant, increasing the plant's susceptibility to other stress factors such as heat, water, and nutritional deficiencies. The stylet is a hard, sharp spear used for feeding.
Muscles move the stylet in and out and allow the nematode to puncture plant cells.
Once plant cells are opened nematodes empty the contents of the cell. Glands empty their contents into the esophagus to help digestion. The median bulb is a circular muscle which pumps food through the esophagus. In the center of the median bulb is a valve which only allows contents to move from the stylet to the intestine. The nerve ring is the largest group of nerve cells in nematodes.