A heteroecious

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

is one that requires at least two hosts. The ''primary host'' is the host in which the parasite spends its adult life; the other is the ''secondary host''. Both hosts are required for the parasite to complete its life cycle. This can be contrasted with an autoecious parasite which can complete its life cycle on a single host species. Many rust fungi have heteroecious life cycles: In

parasitology Parasitology is the study of parasites, their host (biology), hosts, and the relationship between them. As a List of biology disciplines, biological discipline, the scope of parasitology is not determined by the organism or environment in questio ...

, heteroxeny, or heteroxenous development, is a synonymous term that characterizes a

whose development involves several hosts.

Fungal examples

* '' Gymnosporangium'' (Cedar-apple rust): the juniper is the primary ( telial) host and the

apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in late summer into mid-autumn. The pear tree and shrub are a species of genus ''Pyrus'' , in the Family (biology), family Rosaceae, bearing the Pome, po ...

or hawthorn is the secondary ( aecial) host. * '' Cronartium ribicola'' (White pine blister rust): the primary host are white pines, and currants the secondary. * '' Hemileia vastatrix'' (Coffee rust): the primary host is coffee plant, and the alternate host is unknown. * '' Puccinia graminis'' (Stem rust): the primary hosts include Kentucky bluegrass, barley, and wheat; barberry is the alternate host. * ''Puccinia coronata'' var. ''avenae'' (Crown rust of oats): Oats are the primary host; '' Rhamnus'' spp. (Buckthorns) are the alternate hosts. * '' Phakopsora meibomiae'' and '' P. pachyrhizi'' (Soybean Rust): the primary host is soybean and various legumes. The alternate host is unknown. * '' Puccinia porri'' (Leek rust): autoecious

History

The phenomenon of heteroecy was first discovered by A.S. Ørsted in 1863.Ørsted, A.S. (1863) Om Sygdomme hos Planterne, som foraarsages af Snyltesvampe, navnlig om Rust og Brand og om Midlerne til deres Forebyggelse. Kjøbenhavn

References

Parasitology {{Parasite-stub