Meloidogyne incognita is a nematode, a type of roundworm, in the family Heteroderidae. It is an important plant parasite classified in parasitology as a root-knot nematode, as it prefers to attack the root of its host plant.

When M. incognita attacks the roots of plants, it sets up a feeding location, where it deforms the normal root cells and establishes giant cells. The roots become gnarled or nodulated, forming galls, hence the term “root-knot” nematode.

It is commonly called the “southern root-knot nematode” or the “cotton root-knot nematode”. This parasitic roundworm has worldwide distribution and numerous hosts.

M. incognita has been found to be able to move along shallower temperature gradients (0.001C/cm) than any other known organism,^[1] an example of thermotaxis. The response is complicated and thought to allow the nematodes to move toward an appropriate level in soil,^[2] while they search for chemical cues that can guide them to specific roots.^[3][4][5]