Vertical migration of the rice white-tip nematode, Aphelenchoides besseyi.

In the laboratory, the vertical migration of Aphelenchoides besseyi was favored by rough surfaces and an inverse water gradient. In relation th gravity, the nematode migrated down or up equally, a circumstance suggesting that a geotaxis was not involved. Stems of rice seedlings were effective surfaces for vertical migration of nematodes only when the stems were continuously supplied with moisture.