The Canon of Potato Science: 14. Cyst Nematodes

Abstract

Cyst forming nematodes, or cyst nematodes, are one of the most specialized and successful plant-parasitic nematode pests of agriculture. The nematodes have a very narrow host range, which is opposite to root-knot nematodes which are polyphagous. In the case of potato, only the potato cyst nematodes (PCN) Globodera rostochiensis and G. pallida are able to infest the plants. The nematodes originate from South America, were introduced into Europe along with the potato tubers around 1600, and belong to the family Heteroderidae, genus Globodera. The life cycle of cyst nematodes is well adapted to the host and cyst nematodes can survive in various environments. The cyst, the dead body wall of the female, contains the eggs. The eggs hatch in the presence of the host, hatching being triggered by exudates from the host roots. Root exudates from Solanaceae, such as potato, tomato and woody nightshade (bitter sweet), activate these juveniles and can − under suitable environmental conditions − cause up to 80% of the nematodes to hatch. The juveniles enter the roots near the root tip and induce, by injecting saliva, a feeding cell or syncytial “transfer cell”. The juveniles become sedate and feed from the syncytia, until their development is complete after four moulds. After the 4th mould the female is round and swollen and protrudes from the root. The males are slender, leave the roots, mate and fertilize the females. After mating the female forms eggs and when the female dies, the cuticle tans to form a protective cyst with 200−500 eggs within. The life cycle is now complete and the whole cycle may take up to three months. The cyst falls of the root, waiting for the next suitable host plant. Cysts have the size of small pinheads and the juveniles are 0.5 mm long, so it is not the size but the number of nematodes that cause the damage. Infested plants show retarded growth and heavily infested fields normally show badly growing patches, especially under dry conditions. Potato yield can be decreased by up to 50%. Potato Research (2007) 50:259–262 DOI 10.1007/s11540-008-9076-3