A heteroecious

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

is one that requires at least two

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

s. 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 fo ...

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

whose development involves several

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 Amygd ...

'' (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) host and the

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

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 ...

hawthorn Hawthorn or Hawthorns may refer to: Plants * '' Crataegus'' (hawthorn), a large genus of shrubs and trees in the family Rosaceae * ''Rhaphiolepis'' (hawthorn), a genus of about 15 species of evergreen shrubs and small trees in the family Rosace ...

is the secondary (

aecial An aecium (plural aecia) is a specialised reproductive structure found in some plant pathogenic rust fungi that produce aeciospores. Aecia may also be referred to as "cluster cups". The term aecidium (plural aecidia) is used interchangeably but i ...

) host. * ''

Cronartium ribicola ''Cronartium ribicola'' is a species of rust fungus in the family Cronartiaceae that causes the disease white pine blister rust. Other names include: (French), (German), (Spanish). ''Cronartium ribicola'' is native to China, and was subseque ...

'' (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 cof ...

'' (Coffee rust): the primary host is coffee plant, and the alternate host is unknown. * ''

Puccinia graminis Stem rust, also known as cereal rust, black rust, red rust or red dust, is caused by the fungus ''Puccinia graminis'', which causes significant disease in cereal crops. Crop species that are affected by the disease include bread wheat, durum whe ...

'' (Stem rust): the primary hosts include Kentucky bluegrass, barley, and wheat; barberry is the alternate host. * ''

Puccinia coronata ''Puccinia coronata'' is a plant pathogen and causal agent of oat and barley crown rust. The pathogen occurs worldwide, infecting both wild and cultivated oats. Crown rust poses a threat to barley production, because the first infections in barl ...

var. avenae'' (Crown rust of oats): Oats are the primary host; '' Rhamnus'' spp. (Buckthorns) are the alternate hosts. * ''

Phakopsora meibomiae The Phakopsoraceae are a family of rust fungi in the order Pucciniales. The family contains 18 genera and 205 species. Genera *'' Aeciure'' *'' Arthuria'' *'' Batistopsora'' *'' Bubakia'' *'' Catenulopsora'' *'' Cerotelium'' *'' Crossopso ...

'' and '' P. pachyrhizi'' (Soybean Rust): the primary host is soybean and various legumes. The alternate host is unknown. *''

Puccinia porri ''Puccinia porri'' (previously known as ''Puccinia allii'') is a species of rust fungus that causes leek rust. It affects leek, garlic, onion, and chives, and usually appears as bright orange spots on infected plants. Fungus ''Puccinia porri ...

'' (Leek rust):

autoecious A heteroecious parasite 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 cycl ...

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