Distribution and economic importance

Abstract

The family Heteroderidae of plant parasitic nematodes contains the cyst-forming species within the sub-family Heteroderinae, within which the numbers of genera (not all cyst-forming) and species described have increased greatly over the last five decades. When Franklin (1951) published her book on “The cyst-forming species of Heterodera”, cyst nematodes were already a major concern and were known to cause serious yield losses in important food crops such as potatoes, cereals, brassicas, tomatoes and sugar beet. The genus Heterodera Schmidt 1871 was, at that time, considered to be largely temperate, with about 12 species. Today, 67 valid species are recognized in the genus Heterodera alone (Table 1.1). After many studies and revisions in classification (Mulvey, 1972; Stone, 1977; Luc, Maggenti and Fortuner, 1988; Baldwin and Schouest, 1990), the specific characters of many other species that were once members of the genus Heterodera have been accommodated in new genera. These new genera of cyst-forming species are Globodera, Punctodera, Cactodera, Afenestrata and Dolichodera, which are listed with the species they contain in Table 1.2. The cyst-forming genera of the Heteroderinae seem, in general, to have hosts within particular plant families. For instance, the Poaceae support many species of Heterodera and Punctodera. On the other hand, there are examples of unusual host specificity within genera, such as Cactodera betulae, found normally on birch and occasionally alder whilst other species of Cactodera are found on members of the Cactaceae, Amaranthaceae and Chenopodiaceae.