Morphology and ultrastructure

Cyst nematodes (Heteroderinae) comprise at least 17 different genera and include many important species of plant-parasitic nematodes that interfere with agricultural production (Sasser and Freckman, 1987; Baldwin and Mundo-Ocampo, 1991). Infection by cyst nematodes on numerous host plants species around the world causes significant yield losses. Major species of cyst nematodes, such as Heterodera schachtii Schmidt, 1871 on sugar beet, H. glycines Ichinohe, 1952 on soybean, and Globodera rostochiensis (Wollenweber, 1923) Behrens, 1975 and G. pallida (Stone, 1973) Behrens, 1975 on potato, etc., remain of major economic importance worldwide. These costly pests have been the focus of numerous research on various aspects of host-parasite relationships (Wyss and Zunke, 1986a, b).