A heteroecious

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

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 hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question but by their way of life. This means it f ...

heteroxeny Heteroxeny, or heteroxenous development, characterizes a parasite whose development involves several host species. Heteroxeny has been used as the basis for splitting genera. When there are two or three hosts, the development cycle is named di ...

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

whose development involves several hosts.

Fungal examples

* ''

Gymnosporangium ''Gymnosporangium'' is a genus of heteroecious plant-pathogenic fungi which alternately infect members of the family Cupressaceae, primarily species in the genus ''Juniperus'' (junipers), and members of the family Rosaceae in the subfamily Amyg ...

'' (Cedar-apple rust): the

juniper Junipers are coniferous trees and shrubs in the genus ''Juniperus'' () of the cypress family Cupressaceae. Depending on the taxonomy, between 50 and 67 species of junipers are widely distributed throughout the Northern Hemisphere, from the Arcti ...

is the primary (

telial Telium, plural telia, are structures produced by rust fungi as part of the reproductive cycle. They are typically yellow or orange drying to brown or black and are exclusively a mechanism for the release of teliospores which are released by win ...

) host and the

apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus '' Malus''. The tree originated in Central Asia, where its wild ances ...

pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the family Rosaceae, bearing the p ...

or hawthorn is the secondary (

aecial An aecium (plural aecia) is a specialised reproductive structure found in some plant pathogenic rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air mo ...

) host. * '' Cronartium ribicola'' (White pine blister rust): the primary host are white pines, and currants the secondary. * ''

Hemileia vastatrix ''Hemileia vastatrix'' is a multicellular basidiomycete fungus of the order Pucciniales (previously also known as Uredinales) that causes coffee leaf rust (CLR), a disease affecting the coffee plant. Coffee serves as the obligate host of ...

'' (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