An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. This is opposed to a facultative parasite, which can act as a parasite but does not rely on its host to continue its life-cycle. Obligate parasites have evolved a variety of parasitic strategies to exploit their hosts. Holoparasites and some hemiparasites are obligate.
It is advantageous for the parasite to preserve the health of their host when this is compatible with their nutritional and reproductive requirements, except when the death of the host is necessary for transmission.
Obligate parasitism is exhibited in a range of organisms, with examples in viruses, bacteria, fungi, plants, and animals. They are unable to complete their development without passing through at least one parasitic stage which is necessary to their life-cycle.
Whether one regards viruses as living organisms or not, they cannot reproduce except by means of resources within living cells. Accordingly, it is convenient and customary to regard them as obligate intracellular parasites.
Among the Vespidae family, Vespula austriaca is an example of an obligate reproductive parasite; its common host is Vespula acadica. In the genus Bombus, B. bohemicus is an obligate parasite of B. locurum, B. cryptarum, and B. terrestris.
Parasitic life cycles involve the exploitation of at least one host. Parasites that infect a single species are said to have direct life-cycles. For example, the hookworm species Necator americanus. Parasites that infect more than one host are said to have a complex or indirect life-cycle. For example, the malaria plasmodium.
An intermediate or secondary host is exploited by the parasite only for a short transition period. A final or primary host is exploited by the parasite and is the only location in which the parasite is able to reach maturity and if possible, reproduce sexually.
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different undulating pattern than flagella. Cilia occur in all members of the group (although the peculiar Suctoria only have them for part of their life cycle) and are variously used in swimming, crawling, attachment, feeding, and sensation.
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. As of 2022, 2.16 million living animal species have been described—of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates—but it has been estimated there are around 7.
Behavior-altering parasites are parasites with two or more hosts, capable of causing changes in the behavior of one of their hosts to enhance their transmission, sometimes directly affecting the hosts' decision-making and behavior control mechanisms. They do this by making the intermediate host, where they may reproduce asexually, more likely to be eaten by a predator at a higher trophic level which becomes the definitive host where the parasite reproduces sexually; the mechanism is therefore sometimes called parasite increased trophic facilitation or parasite increased trophic transmission.
All life forms on earth ultimately descended from a primordial population dubbed the last universal common ancestor or LUCA via Darwinian evolution. Extant living systems share two salient functional features, a metabolism extracting and transforming energ ...
2023
, , , ,
The density of dinoflagellate microalgae in the tissue of symbiotic corals is an important determinant for health and productivity of the coral animal. Yet, the specific mechanism for their regulation and the consequence for coral nutrition are insufficien ...
ROYAL SOC2020
,
Acta Tropica is an international, peer-reviewed journal advancing scientific research in the fields of tropical medicine and parasitology. This article elucidates the rich history of the journal and speculates about its future. Acta Tropica was launched in ...