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Alternate Host vs. Collateral Host: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on January 27, 2024
An alternate host is a secondary organism a parasite uses to complete its life cycle, while a collateral host is an incidental host not essential for the parasite's lifecycle.

Key Differences

An alternate host plays a crucial role in the life cycle of certain parasites, necessary for completing specific developmental stages. Collateral hosts, however, are incidental and not a required part of the parasite's life cycle.
Parasites using an alternate host typically have complex life cycles, requiring different hosts for various stages. In contrast, parasites in collateral hosts do not undergo essential developmental changes in these hosts.
Alternate hosts are often specific, with the parasite needing a particular species to progress its lifecycle. Collateral hosts can be a wider range of organisms, where the parasite can survive but not necessarily thrive or reproduce.
In agricultural contexts, understanding and managing alternate hosts is crucial for breaking the life cycle of pests. Collateral hosts are less critical in such management strategies, as they do not contribute directly to the pest's lifecycle.
An example of an alternate host is a wheat plant for stem rust fungus, which requires barberry to complete its cycle. Collateral hosts, like certain mammals for tick species, provide temporary habitat but are not essential for reproduction.

Comparison Chart

Role in Lifecycle

Essential for completing life cycle
Incidental, not essential for life cycle

Developmental Changes

Undergoes key stages in alternate host
Does not undergo key lifecycle stages


Often species-specific
Can be a wider range of species

Importance in Management

Crucial for breaking life cycles of parasites
Less critical in lifecycle management


Wheat in the life cycle of stem rust fungus
Mammals as hosts for certain tick species

Alternate Host and Collateral Host Definitions

Alternate Host

Alternate hosts often differ significantly from the primary host in terms of species and environment.
For some parasites, the alternate host can be an entirely different species from the primary host.

Collateral Host

Parasites in collateral hosts may survive or temporarily thrive, but do not complete their lifecycle.
The parasite remained dormant while in the collateral host.

Alternate Host

In the life cycle of some parasites, the alternate host is where sexual or asexual reproduction occurs.
In its alternate host, the parasite undergoes sexual reproduction essential for its survival.

Collateral Host

Collateral hosts are often part of accidental infestations and not targeted in lifecycle management.
The bird, a collateral host, was an unintended part of the parasite's spread.

Alternate Host

Alternate hosts are essential for certain parasites to complete their developmental cycles.
The barberry bush is an important alternate host for the wheat stem rust fungus.

Collateral Host

A collateral host is an incidental host that a parasite can inhabit, but is not necessary for its lifecycle.
The rabbit acted as a collateral host for the tick, providing temporary sustenance.

Alternate Host

An alternate host is an organism a parasite uses to complete a specific stage of its life cycle.
The apple tree serves as an alternate host for the cedar-apple rust fungus.

Collateral Host

Collateral hosts do not play a critical role in the parasite's developmental stages.
In this collateral host, the parasite survives but does not undergo significant development.

Alternate Host

Managing alternate hosts is a key strategy in controlling agricultural pests.
Farmers often remove alternate hosts from fields to prevent the spread of certain diseases.

Collateral Host

Collateral hosts can sometimes act as dead-end hosts, where the parasite cannot progress.
In the collateral host, the parasite reached a dead-end, unable to reproduce or mature.


What is an alternate host?

An alternate host is a secondary host necessary for a parasite to complete its lifecycle.

Can a collateral host become a primary host?

Typically, a collateral host does not become a primary host as it is not integral to the parasite's lifecycle.

Why is an alternate host important for some parasites?

An alternate host is important as it allows the parasite to complete essential developmental stages.

What is a collateral host?

A collateral host is an incidental host that a parasite can inhabit, but is not essential for its lifecycle.

Do parasites reproduce in collateral hosts?

Generally, parasites do not reproduce or complete their lifecycle in collateral hosts.

How do parasites reach alternate hosts?

Parasites reach alternate hosts through various means, such as vectors, environmental transfer, or direct contact.

What role do alternate hosts play in agriculture?

In agriculture, alternate hosts are important in the management and control of plant diseases and pests.

Are collateral hosts usually accidental?

Yes, collateral hosts are often accidental and not a deliberate part of the parasite's lifecycle.

How does an alternate host differ from a primary host?

An alternate host is used for specific lifecycle stages, whereas a primary host is central to the parasite's survival and reproduction.

Are alternate hosts specific to certain parasites?

Yes, alternate hosts are often specific to certain parasites and are crucial for their developmental stages.

Can any organism be a collateral host?

While not any organism, a wide range of species can serve as collateral hosts for different parasites.

Can a collateral host harm the parasite?

In some cases, a collateral host can be a dead-end for the parasite, preventing further development or spread.

How long can a parasite survive in a collateral host?

The survival time of a parasite in a collateral host varies, depending on the parasite and host conditions.

Are there benefits to a parasite in a collateral host?

The main benefit for a parasite in a collateral host is temporary sustenance or shelter.

Do alternate hosts show symptoms of infestation?

Yes, alternate hosts can show symptoms, especially if the parasite's presence affects their health.

Can a collateral host spread the parasite to a primary or alternate host?

It's possible, though not typical, for a collateral host to spread the parasite to a primary or alternate host.

Can removing alternate hosts control a parasite's spread?

Yes, removing alternate hosts can be an effective way to break the parasite's lifecycle and control its spread.

Is a collateral host part of a parasite's natural lifecycle?

A collateral host is not a planned part of the lifecycle but can be utilized by the parasite incidentally.

Is it necessary to identify alternate hosts in pest control?

Yes, identifying alternate hosts is critical in effective pest control strategies.

Can a single organism be both an alternate and collateral host for different parasites?

Yes, an organism can serve as an alternate host for one parasite and a collateral host for another.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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