Wikipedia

Parasitism

(Redirected fromParasites)
This is thelatest accepted revision,reviewedon26 November 2024.
"Parasite" redirects here. For other uses, seeParasite (disambiguation).

Parasitismis aclose relationshipbetweenspecies,where one organism, the parasite, lives on or inside another organism, thehost,causing it some harm, and isadaptedstructurally to this way of life.[1]The entomologistE. O. Wilsoncharacterised parasites as "predators that eat prey in units of less than one".[2]Parasites include single-celledprotozoanssuch as the agents ofmalaria,sleeping sickness,andamoebic dysentery;animals such ashookworms,lice,mosquitoes,andvampire bats;fungisuch ashoney fungusand the agents ofringworm;and plants such asmistletoe,dodder,and thebroomrapes.

Afish parasite,the isopodCymothoa exigua,replacing the tongue of aLithognathus

There are six major parasiticstrategiesof exploitation of animal hosts, namelyparasitic castration,directly transmitted parasitism (by contact),trophically-transmittedparasitism (by being eaten),vector-transmittedparasitism,parasitoidism,and micropredation. One major axis of classification concerns invasiveness: an endoparasite lives inside the host's body; an ectoparasite lives outside, on the host's surface.

Like predation, parasitism is a type ofconsumer–resource interaction,[3]but unlikepredators,parasites, with the exception of parasitoids, are much smaller than their hosts, do not kill them, and often live in or on their hosts for an extended period. Parasites of animals are highlyspecialised,each parasite species living on one given animal species, andreproduceat a faster rate than their hosts. Classic examples include interactions betweenvertebratehosts andtapeworms,flukes,and those between the malaria-causingPlasmodiumspecies, andfleas.

Parasites reduce hostfitnessby general or specialisedpathology,that ranges fromparasitic castrationtomodification of host behaviour.Parasites increase their own fitness by exploiting hosts for resources necessary for their survival, in particular by feeding on them and by using intermediate (secondary) hosts to assist in theirtransmissionfrom one definitive (primary) host to another. Although parasitism is often unambiguous, it is part of a spectrum of interactions betweenspecies,grading via parasitoidism into predation, through evolution intomutualism,and in some fungi, shading into beingsaprophytic.

Human knowledge of parasites such asroundwormsandtapewormsdates back toancient Egypt,Greece,andRome.Inearly moderntimes,Antonie van LeeuwenhoekobservedGiardia lambliawith his microscope in 1681, whileFrancesco Redidescribed internal and external parasites includingsheep liver flukeandticks.Modernparasitologydeveloped in the 19th century. In human culture, parasitism has negative connotations. These were exploited tosatiricaleffect inJonathan Swift's 1733 poem "On Poetry: A Rhapsody", comparing poets tohyperparasitical"vermin". In fiction,Bram Stoker's 1897Gothic horrornovelDraculaand its many later adaptations featured ablood-drinkingparasite.Ridley Scott's 1979 filmAlienwas one of many works ofscience fictionto feature a parasitic alien species.[4]

Etymology

edit

First used in English in 1539, the wordparasitecomes from theMedieval Frenchparasite,from theLatinisedformparasitus,fromAncient Greekπαράσιτος[5](parasitos)'one who eats at the table of another'in turn fromπαρά[6](para)'beside, by' andσῖτος(sitos)'wheat, food'.[7]The related termparasitismappears in English from 1611.[8]

Evolutionary strategies

edit
See also:Parasitology

Basic concepts

edit
Further information:Parasitic life cycle
Head (scolex) of tapewormTaenia solium,anintestinal parasite,has hooks andsuckersto attach to itshost

Parasitism is a kind ofsymbiosis,a close and persistent long-term biological interaction between a parasite and its host. Unlikesaprotrophs,parasites feed on living hosts, though some parasitic fungi, for instance, may continue to feed on hosts they have killed. Unlikecommensalismandmutualism,the parasitic relationship harms the host, either feeding on it or, as in the case of intestinal parasites, consuming some of its food. Because parasites interact with other species, they can readily act asvectorsof pathogens, causingdisease.[9][10][11]Predationis by definition not a symbiosis, as the interaction is brief, but the entomologistE. O. Wilsonhas characterised parasites as "predators that eat prey in units of less than one".[2]

Within that scope are many possible strategies.Taxonomistsclassify parasites in a variety of overlapping schemes, based on their interactions with their hosts and on theirlife cycles,which can be complex. Anobligate parasitedepends completely on the host to complete its life cycle, while afacultative parasitedoes not. Parasite life cycles involving only one host are called "direct"; those with a definitive host (where the parasite reproduces sexually) and at least one intermediate host are called "indirect".[12][13]An endoparasite lives inside the host's body; an ectoparasite lives outside, on the host's surface.[14]Mesoparasites—like somecopepods,for example—enter an opening in the host's body and remain partly embedded there.[15]Some parasites can be generalists, feeding on a wide range of hosts, but many parasites, and the majority of protozoans andhelminthsthat parasitise animals, are specialists and extremely host-specific.[14]An early basic, functional division of parasites distinguished microparasites and macroparasites. These each had amathematical modelassigned in order to analyse the population movements of the host–parasite groupings.[16]The microorganisms and viruses that can reproduce and complete their life cycle within the host are known as microparasites. Macroparasites are the multicellular organisms that reproduce and complete their life cycle outside of the host or on the host's body.[16][17]

Much of the thinking on types of parasitism has focused on terrestrial animal parasites of animals, such as helminths. Those in other environments and with other hosts often have analogous strategies. For example, thesnubnosed eelis probably a facultative endoparasite (i.e., it is semiparasitic) that opportunistically burrows into and eats sick and dying fish.[18]Plant-eatinginsects such asscale insects,aphids,andcaterpillarsclosely resemble ectoparasites, attacking much larger plants; they serve as vectors of bacteria, fungi and viruses which causeplant diseases.As female scale insects cannot move, they are obligate parasites, permanently attached to their hosts.[16]

The sensory inputs that a parasite employs to identify and approach a potential host are known as "host cues". Such cues can include, for example, vibration,[19]exhaledcarbon dioxide,skin odours, visual and heat signatures, and moisture.[20]Parasitic plants can use, for example, light, host physiochemistry, and volatiles to recognize potential hosts.[21]

Major strategies

edit

There are six major parasiticstrategies,namelyparasitic castration;directly transmitted parasitism;trophically-transmitted parasitism;vector-transmitted parasitism;parasitoidism;and micropredation. These apply to parasites whose hosts are plants as well as animals.[16][22]These strategies representadaptive peaks;intermediate strategies are possible, but organisms in many different groups have consistentlyconvergedon these six, which are evolutionarily stable.[22]

A perspective on the evolutionary options can be gained by considering four key questions: the effect on thefitnessof a parasite's hosts; the number of hosts they have per life stage; whether the host is prevented from reproducing; and whether the effect depends on intensity (number of parasites per host). From this analysis, the major evolutionary strategies of parasitism emerge, alongside predation.[23]

Evolutionary strategies in parasitism and predation[23]
(Intensity-dependent: green, roman;
Intensity-independent: purple, italics)
Hostfitness Single host, stays alive Single host, dies Multiple hosts
Able to
reproduce
(fitness > 0)		 Conventional parasite
Pathogen		 Trophically-transmitted parasite[a]
Trophically-transmitted pathogen		 Micropredator
Micropredator
Unable to
reproduce
(fitness = 0)		 -----
Parasitic castrator		 Trophically-transmitted parasitic castrator
Parasitoid		 Social predator[b]
Solitary predator

Parasitic castrators

edit
Main article:Parasitic castration
The parasitic castratorSacculina carcini(highlighted) attached toits crab host

Parasitic castratorspartly or completely destroy their host's ability to reproduce, diverting the energy that would have gone into reproduction into host and parasite growth, sometimes causing gigantism in the host. The host's other systems remain intact, allowing it to survive and to sustain the parasite.[22][24]Parasitic crustaceans such as those in the specialisedbarnaclegenusSacculinaspecifically cause damage to the gonads of their many species[25]of hostcrabs.In the case ofSacculina,the testes of over two-thirds of their crab hosts degenerate sufficiently for these male crabs to develop femalesecondary sex characteristicssuch as broader abdomens, smallerclawsand egg-grasping appendages. Various species of helminth castrate their hosts (such as insects and snails). This may happen directly, whether mechanically by feeding on their gonads, or by secreting a chemical that destroys reproductive cells; or indirectly, whether by secreting a hormone or by diverting nutrients. For example, thetrematodeZoogonus lasius,whosesporocystslack mouths, castrates the intertidal marine snailTritia obsoletachemically, developing in its gonad and killing its reproductive cells.[24][26]

Directly transmitted

edit
Human head-liceare directly transmittedobligateectoparasites

Directly transmitted parasites, not requiring a vector to reach their hosts, include such parasites of terrestrial vertebrates as lice and mites; marine parasites such ascopepodsandcyamidamphipods;monogeneans;and many species of nematodes, fungi, protozoans, bacteria, and viruses. Whether endoparasites or ectoparasites, each has a single host-species. Within that species, most individuals are free or almost free of parasites, while a minority carry a large number of parasites; this is known as anaggregated distribution.[22]

Trophically transmitted

edit
Clonorchis sinensis,the Chinese liver fluke, is trophically transmitted

Trophically-transmitted parasites are transmitted by being eaten by a host. They include trematodes (all exceptschistosomes),cestodes,acanthocephalans,pentastomids,manyroundworms,and many protozoa such asToxoplasma.[22]They have complex life cycles involving hosts of two or more species. In their juvenile stages they infect and oftenencystin the intermediate host. When the intermediate-host animal is eaten by a predator, the definitive host, the parasite survives the digestion process and matures into an adult; some live asintestinal parasites.Many trophically transmitted parasitesmodify the behaviourof their intermediate hosts, increasing their chances of being eaten by a predator. As with directly transmitted parasites, the distribution of trophically transmitted parasites among host individuals is aggregated.[22]Coinfectionby multiple parasites is common.[27]Autoinfection,where (by exception) the whole of the parasite'slife cycletakes place in a single primary host, can sometimes occur in helminths such asStrongyloides stercoralis.[28]

Vector-transmitted

edit
Further information:Disease vector
Thevector-transmittedprotozoan endoparasiteTrypanosomaamong humanred blood cells

Vector-transmittedparasites rely on a third party, an intermediate host, where the parasite does not reproduce sexually,[14]to carry them from one definitive host to another.[22]These parasites are microorganisms, namelyprotozoa,bacteria,orviruses,often intracellularpathogens(disease-causers).[22]Their vectors are mostlyhematophagicarthropods such as fleas, lice, ticks, and mosquitoes.[22][29]For example, the deer tickIxodes scapularisacts as a vector for diseases includingLyme disease,babesiosis,andanaplasmosis.[30]Protozoan endoparasites, such as themalarialparasites in the genusPlasmodiumand sleeping-sickness parasites in the genusTrypanosoma,have infective stages in the host's blood which are transported to new hosts by biting insects.[31]

Parasitoids

edit
Main articles:ParasitoidandParasitoid wasp

Parasitoidsare insects which sooner or later kill their hosts, placing their relationship close to predation.[32]Most parasitoids areparasitoid waspsor otherhymenopterans;others includedipteranssuch asphorid flies.They can be divided into two groups, idiobionts and koinobionts, differing in their treatment of their hosts.[33]

Idiobiontparasitoids sting their often-large prey on capture, either killing them outright or paralysing them immediately. The immobilised prey is then carried to a nest, sometimes alongside other prey if it is not large enough to support a parasitoid throughout its development. Anegg is laidon top of the prey and the nest is then sealed. The parasitoid develops rapidly through its larval and pupal stages,feeding on the provisionsleft for it.[33]

Koinobiontparasitoids, which includefliesas well as wasps, lay their eggs inside young hosts, usually larvae. These are allowed to go on growing, so the host and parasitoid develop together for an extended period, ending when the parasitoids emerge as adults, leaving the prey dead, eaten from inside. Some koinobionts regulate their host's development, for example preventing it frompupatingor making itmoultwhenever the parasitoid is ready to moult. They may do this by producing hormones that mimic the host's moulting hormones (ecdysteroids), or by regulating the host's endocrine system.[33]

Micropredators

edit
Mosquitoesare micropredators and important vectors of disease

A micropredator attacks more than one host, reducing each host's fitness by at least a small amount, and is only in contact with any one host intermittently. This behavior makes micropredators suitable as vectors, as they can pass smaller parasites from one host to another.[22][23][34]Most micropredators arehematophagic,feeding on blood. They include annelids such asleeches,crustaceans such asbranchiuransandgnathiidisopods, variousdipteranssuch as mosquitoes andtsetse flies,other arthropods such as fleas and ticks, vertebrates such aslampreys,and mammals such asvampire bats.[22]

Transmission strategies

edit
Life cycleofEntamoeba histolytica,an anaerobic parasitic protozoan transmitted by thefecal–oral route

Parasites use a variety of methods to infect animal hosts, including physical contact, thefecal–oral route,free-living infectious stages, and vectors, suiting their differing hosts, life cycles, and ecological contexts.[35]Examples to illustrate some of the many possible combinations are given in the table.

Examples of transmission methods in different ecological contexts[35]
Parasite Host Transmission method Ecological context
Gyrodactylus turnbulli
(amonogenean)		 Poecilia reticulata
(guppy)		 physical contact social behaviour
Nematodes
e.g.Strongyloides		 Macaca fuscata
(Japanese macaque)		 fecal–oral

social behaviour
(grooming)

Heligmosomoides polygyrus
(a nematode)		 Apodemus flavicollis
(yellow-necked mouse)		 fecal–oral sex-biased transmission
(mainly to males)
Amblyomma
(a tick)		 Sphenodon punctatus
(tuatara)		 free-living infectious stages social behaviour
Plasmodium
(malariaparasite)		 Birds,mammals
(inc. humans)		 Anophelesmosquito vector,
attracted by odour of
infected human host[36]		 —

Variations

edit

Among the many variations on parasitic strategies are hyperparasitism,[37]social parasitism,[38]brood parasitism,[39]kleptoparasitism,[40]sexual parasitism,[41]and adelphoparasitism.[42]

Hyperparasitism

edit
Main article:Hyperparasite

Hyperparasitesfeed on another parasite, as exemplified by protozoa living in helminth parasites,[37]or facultative or obligate parasitoids whose hosts are either conventional parasites or parasitoids.[22][33]Levels of parasitism beyond secondary also occur, especially among facultative parasitoids. Inoak gallsystems, there can be up to five levels of parasitism.[43]

Hyperparasites can control their hosts' populations, and are used for this purposein agricultureand to some extent inmedicine.The controlling effects can be seen in the way that theCHV1 virushelps to control the damage thatchestnut blight,Cryphonectria parasitica,does toAmerican chestnuttrees, and in the way thatbacteriophagescan limit bacterial infections. It is likely, though little researched, that most pathogenic microparasites have hyperparasites which may prove widely useful in both agriculture and medicine.[44]

Social parasitism

edit
Further information:Ant mimicry,Cuckoo bee,andEmery's rule

Social parasites take advantage of interspecific interactions between members ofeusocialanimals such asants,termites,andbumblebees.Examples include the large blue butterfly,Phengaris arion,its larvae employingant mimicryto parasitise certain ants,[38]Bombus bohemicus,a bumblebee which invades the hives of other bees and takes over reproduction while their young are raised by host workers, andMelipona scutellaris,a eusocial bee whose virgin queens escape killer workers and invade another colony without a queen.[45]An extreme example of interspecific social parasitism is found in the antTetramorium inquilinum,an obligate parasite which lives exclusively on the backs of otherTetramoriumants.[46]A mechanism for the evolution of social parasitism was first proposed by Carlo Emery in 1909.[47]Now known as "Emery's rule",it states that social parasites tend to be closely related to their hosts, often being in the same genus.[48][49][50]

Intraspecific social parasitism occurs in parasitic nursing, where some individual young take milk from unrelated females. Inwedge-capped capuchins,higher ranking females sometimes take milk from low ranking females without any reciprocation.[51]

Brood parasitism

edit
Further information:Brood parasitism

Inbrood parasitism,the hosts suffer increased parental investment and energy expenditure to feed parasitic young, which are commonly larger than host young. The growth rate of host nestlings is slowed, reducing the host's fitness. Brood parasites include birds in different families such ascowbirds,whydahs,cuckoos,andblack-headed ducks.These do not build nests of their own, but leave their eggs in nests of otherspecies.In the familyCuculidae,over 40% of cuckoo species are obligate brood parasites, while others are either facultative brood parasites or provide parental care.[52]The eggs of some brood parasitesmimicthose of their hosts, while some cowbird eggs have tough shells, making them hard for the hosts to kill by piercing, both mechanisms implying selection by the hosts against parasitic eggs.[39][53][54]The adult femaleEuropean cuckoofurther mimics a predator, theEuropean sparrowhawk,giving her time to lay her eggs in the host's nest unobserved.[55]Host species often combat parasitic egg mimicry through eggpolymorphism,having two or more egg phenotypes within a single population of a species. Multiple phenotypes in host eggs decrease the probability of a parasitic species accurately "matching" their eggs to host eggs.[56]

Kleptoparasitism

edit
Further information:Kleptoparasitism

Inkleptoparasitism(from Greek κλέπτης (kleptēs), "thief" ), parasites steal food gathered by the host. The parasitism is often on close relatives, whether within the same species or between species in the same genus or family. For instance, the many lineages ofcuckoo beeslay their eggs in the nest cells of otherbeesin the same family.[40]Kleptoparasitism is uncommon generally but conspicuous in birds; some such asskuasare specialised in pirating food from other seabirds, relentlessly chasing them down until they disgorge their catch.[57]

Sexual parasitism

edit
Main article:Sexual parasitism

A unique approach is seen in some species ofanglerfish,such asCeratias holboelli,where the males are reduced to tinysexual parasites,wholly dependent on females of their own species for survival, permanently attached below the female's body, and unable to fend for themselves. The female nourishes the male and protects him from predators, while the male gives nothing back except the sperm that the female needs to produce the next generation.[41]

Adelphoparasitism

edit

Adelphoparasitism, (from Greekἀδελφός(adelphós), brother[58]), also known as sibling-parasitism, occurs where the host species is closely related to the parasite, often in the same family or genus.[42]In the citrus blackfly parasitoid,Encarsia perplexa,unmated females may layhaploideggs in the fully developed larvae of their own species, producing male offspring,[59]while the marine wormBonellia viridishas a similar reproductive strategy, although the larvae are planktonic.[60]

Illustrations

edit

Examples of the major variant strategies are illustrated.

Taxonomic range

edit

Parasitism has an extremely wide taxonomic range, including animals, plants, fungi, protozoans, bacteria, and viruses.[61]

Animals

edit
Further information:List of parasitic organisms
Major parasitic animal groups[62]
Phylum Class/Order No. of
species 		Endo-
paras.		 Ecto-
paras.		 Invert
def. host		 Vert
def. host		 No. of
hosts		 Marine Fresh-
water		 Terres-
trial
Cnidaria Myxozoa 1,350 Yes Yes 2 or more Yes Yes
Cnidaria Polypodiozoa 1 Yes Yes 1 Yes
Flatworms Trematodes 15,000 Yes Yes 2 or more Yes Yes Yes
Flatworms Monogeneans 20,000 Yes Yes 1 Yes Yes
Flatworms Cestodes 5,000 Yes Yes 2 or more Yes Yes Yes
Horsehair worms 350 Yes Yes 1 or more Yes Yes
Nematodes 10,500 Yes Yes Yes 1 or more Yes Yes Yes
Acanthocephala 1,200 Yes Yes 2 or more Yes Yes Yes
Annelids Leeches 400 Yes Yes 1 Yes Yes
Molluscs Bivalves 600 Yes Yes 1 Yes
Molluscs Gastropods 5,000 Yes Yes 1 Yes
Arthropods Ticks 800 Yes Yes 1 or more Yes
Arthropods Mites 30,000 Yes Yes Yes Yes 1 Yes Yes Yes
Arthropods Copepods 4,000 Yes Yes Yes 1 Yes Yes
Arthropods Lice 4,000 Yes Yes 1 Yes
Arthropods Fleas 2,500 Yes Yes 1 Yes
Arthropods True flies 2,300 Yes Yes 1 Yes
Arthropods Twisted-wing insects 600 Yes Yes 1 Yes
Arthropods Parasitoid wasps 130,000[63]- 1,100,000[64] Yes Yes Yes 1 Yes

Parasitism is widespread in the animal kingdom,[65]and has evolved independently from free-living forms hundreds of times.[22]Many types ofhelminthincludingflukesandcestodeshave complete life cycles involving two or more hosts. By far the largest group is the parasitoid wasps in the Hymenoptera.[22]Thephylaandclasseswith the largest numbers of parasitic species are listed in the table. Numbers are conservative minimum estimates. The columns for Endo- and Ecto-parasitism refer to the definitive host, as documented in the Vertebrate and Invertebrate columns.[62]

Plants

edit
Main article:Parasitic plant
Cuscuta(a dodder), a stemholoparasite,on anacaciatree

Ahemiparasiteorpartial parasitesuch asmistletoederives some of its nutrients from another living plant, whereas aholoparasitesuch asCuscutaderives all of its nutrients from another plant.[66]Parasitic plantsmake up about one per cent ofangiospermsand are in almost everybiomein the world.[67][68][69]All these plants have modified roots,haustoria,which penetrate the host plants, connecting them to the conductive system—either thexylem,thephloem,or both. This provides them with the ability to extract water and nutrients from the host. A parasitic plant is classified depending on where it latches onto the host, either the stem or the root, and the amount of nutrients it requires. Since holoparasites have nochlorophylland therefore cannot make food for themselves byphotosynthesis,they are always obligate parasites, deriving all their food from their hosts.[68]Some parasitic plants can locate theirhostplants by detectingchemicalsin the air or soil given off by hostshootsorroots,respectively. About 4,500speciesof parasitic plant in approximately 20familiesofflowering plantsare known.[68][70]

Species within theOrobanchaceae(broomrapes) are among the most economically destructive of all plants. Species ofStriga(witchweeds) are estimated to cost billions of dollars a year in crop yield loss, infesting over 50 million hectares of cultivated land within Sub-Saharan Africa alone.Strigainfects both grasses and grains, includingcorn,rice,andsorghum,which are among the world's most important food crops.Orobanchealso threatens a wide range of other important crops, includingpeas,chickpeas,tomatoes,carrots,and varieties ofcabbage.Yield loss fromOrobanchecan be total; despite extensive research, no method of control has been entirely successful.[71]

Manyplantsandfungiexchange carbon and nutrients in mutualisticmycorrhizalrelationships. Some 400 species ofmyco-heterotrophicplants, mostly in the tropics, however effectivelycheatby taking carbon from a fungus rather than exchanging it for minerals. They have much reduced roots, as they do not need to absorb water from the soil; their stems are slender with fewvascular bundles,and their leaves are reduced to small scales, as they do not photosynthesize. Their seeds are small and numerous, so they appear to rely on being infected by a suitable fungus soon after germinating.[72]

The honey fungus,Armillaria mellea,is a parasite of trees, and asaprophytefeeding on the trees it has killed.

Fungi

edit
Further information:Pathogenic fungusandPlant pathology

Parasiticfungiderive some or all of their nutritional requirements from plants, other fungi, or animals.

Plant pathogenic fungi are classified into three categories depending on their mode of nutrition: biotrophs,hemibiotrophsand necrotrophs. Biotrophic fungi derive nutrients from living plant cells, and during the course of infection they colonise their plant host in such a way as to keep it alive for a maximally long time.[73]One well-known example of a biotrophic pathogen isUstilago maydis,causative agent of the corn smut disease. Necrotrophic pathogens on the other hand, kill host cells and feedsaprophytically,an example being the root-colonising honey fungi in the genusArmillaria.[74]Hemibiotrophic pathogens begin their colonising their hosts as biotrophs, and subsequently killing off host cells and feeding as necrotrophs, a phenomenon termed thebiotrophy-necrotrophy switch.[75]

Pathogenic fungi are well-known causative agents of diseases on animals as well as humans. Fungal infections (mycosis) are estimated to kill 1.6 million people each year.[76]One example of a potent fungal animal pathogen areMicrosporidia- obligate intracellular parasitic fungi that largely affect insects, but may also affect vertebrates including humans, causing the intestinal infectionmicrosporidiosis.[77]

Borrelia burgdorferi,the bacterium that causesLyme disease,is transmitted byIxodesticks.

Protozoa

edit
Further information:Human parasite § Protozoa

Protozoa such asPlasmodium,Trypanosoma,andEntamoeba[78]are endoparasitic. They cause serious diseases in vertebrates including humans—in these examples, malaria, sleeping sickness, andamoebic dysentery—and have complex life cycles.[31]

Bacteria

edit
Main article:Pathogenic bacteria

Many bacteria are parasitic, though they are more generally thought of aspathogenscausing disease.[79]Parasitic bacteria are extremely diverse, and infect their hosts by a variety of routes. To give a few examples,Bacillus anthracis,the cause ofanthrax,is spread by contact with infecteddomestic animals;itsspores,which can survive for years outside the body, can enter a host through an abrasion or may be inhaled.Borrelia,the cause ofLyme diseaseandrelapsing fever,is transmitted by vectors, ticks of the genusIxodes,from the diseases' reservoirs in animals such asdeer.Campylobacter jejuni,a cause ofgastroenteritis,is spread by the fecal–oral route from animals, or by eating insufficiently cookedpoultry,or by contaminated water.Haemophilus influenzae,an agent ofbacterial meningitisand respiratory tract infections such asinfluenzaandbronchitis,is transmitted by droplet contact.Treponema pallidum,the cause ofsyphilis,isspreadbysexual activity.[80]

Enterobacteria phage T4is abacteriophagevirus. It infects its host,Escherichia coli,by injecting its DNA through its tail, which attaches to the bacterium's surface.

Viruses

edit
Main articles:VirusandBacteriophage

Virusesare obligate intracellular parasites, characterised by extremely limited biological function, to the point where, while they are evidently able to infect all other organisms from bacteria andarchaeato animals, plants and fungi, it is unclear whether they can themselves be described as living. They can be eitherRNAorDNA virusesconsisting of a single or double strand ofgenetic material(RNAorDNA,respectively), covered in aproteincoat and sometimes alipidenvelope. They thus lack all the usual machinery of thecellsuch asenzymes,relying entirely on the host cell's ability to replicate DNA and synthesise proteins. Most viruses arebacteriophages,infecting bacteria.[81][82][83][84]

Evolutionary ecology

edit
Restoration of aTyrannosauruswith holes possibly caused by aTrichomonas-like parasite
Further information:Evolutionary ecology

Parasitism is a major aspect of evolutionary ecology; for example, almost all free-living animals are host to at least one species of parasite. Vertebrates, the best-studied group, are hosts to between 75,000 and 300,000 species of helminths and an uncounted number of parasitic microorganisms. On average, a mammal species hosts four species of nematode, two of trematodes, and two of cestodes.[85]Humans have 342 species of helminth parasites, and 70 species of protozoan parasites.[86]Some three-quarters of the links infood websinclude a parasite, important in regulating host numbers. Perhaps 40 per cent of described species are parasitic.[85]

Fossil record

edit
Further information:Paleoparasitology

Parasitism is hard to demonstrate from thefossil record,but holes in themandiblesof several specimens ofTyrannosaurusmay have been caused byTrichomonas-like parasites.[87]Saurophthirus,the Early Cretaceousflea,parasitizedpterosaurs.[88][89]Eggs that belonged tonematodeworms and probablyprotozoancystswere found in the Late Triassiccoproliteofphytosaur.This rare find in Thailand reveals more about the ecology of prehistoric parasites.[90]

Coevolution

edit
Further information:Host–parasite coevolution

As hosts and parasites evolve together, their relationships often change. When a parasite is in a sole relationship with a host, selection drives the relationship to become more benign, even mutualistic, as the parasite can reproduce for longer if its host lives longer.[91]But where parasites are competing, selection favours the parasite that reproduces fastest, leading to increased virulence. There are thus varied possibilities inhost–parasite coevolution.[92]

Evolutionary epidemiologyanalyses how parasites spread and evolve, whereasDarwinian medicineapplies similar evolutionary thinking to non-parasitic diseases likecancerandautoimmune conditions.[93]

Long-term partnerships favouring mutualism

edit
Wolbachiabacteria within an insect cell

Long-term partnerships can lead to a relatively stable relationship tending tocommensalismormutualism,as, all else being equal, it is in the evolutionary interest of the parasite that its host thrives. A parasite may evolve to become less harmful for its host or a host may evolve to cope with the unavoidable presence of a parasite—to the point that the parasite's absence causes the host harm. For example, although animals parasitised bywormsare often clearly harmed, such infections may also reduce the prevalence and effects ofautoimmunedisorders in animal hosts, including humans.[91]In a more extreme example, somenematodeworms cannot reproduce, or even survive, without infection byWolbachiabacteria.[94]

Lynn Margulisand others have argued, followingPeter Kropotkin's 1902Mutual Aid: A Factor of Evolution,that natural selection drives relationships from parasitism to mutualism when resources are limited. This process may have been involved in thesymbiogenesiswhich formed theeukaryotesfrom an intracellular relationship betweenarchaeaand bacteria, though the sequence of events remains largely undefined.[95][96]

Competition favouring virulence

edit

Competition between parasites can be expected to favour faster reproducing and therefore morevirulentparasites, bynatural selection.[92][97]

Biologists long suspectedcospeciationofflamingosandduckswith their parasiticlice,which were similar in the two families. Cospeciation did occur, but it led to flamingos andgrebes,with a laterhost switchof flamingo lice to ducks.

Among competing parasitic insect-killing bacteria of the generaPhotorhabdusandXenorhabdus,virulence depended on the relative potency of the antimicrobialtoxins(bacteriocins) produced by the two strains involved. When only one bacterium could kill the other, the other strain was excluded by the competition. But whencaterpillarswere infected with bacteria both of which had toxins able to kill the other strain, neither strain was excluded, and their virulence was less than when the insect was infected by a single strain.[92]

Cospeciation

edit

A parasite sometimes undergoescospeciationwith its host, resulting in the pattern described inFahrenholz's rule,that the phylogenies of the host and parasite come to mirror each other.[98]

An example is between thesimian foamy virus(SFV) and its primate hosts. The phylogenies of SFV polymerase and the mitochondrialcytochrome c oxidase subunit IIfrom African and Asian primates were found to be closely congruent in branching order and divergence times, implying that the simian foamy viruses cospeciated with Old World primates for at least 30 million years.[99]

The presumption of a shared evolutionary history between parasites and hosts can help elucidate how host taxa are related. For instance, there has been a dispute about whetherflamingosare more closely related tostorksorducks.The fact that flamingos share parasites with ducks and geese was initially taken as evidence that these groups were more closely related to each other than either is to storks. However, evolutionary events such as the duplication, or the extinction of parasite species (without similar events on the host phylogeny) often erode similarities between host and parasite phylogenies. In the case of flamingos, they have similar lice to those ofgrebes.Flamingos and grebes do have a common ancestor, implying cospeciation of birds and lice in these groups. Flamingo lice thenswitched hoststo ducks, creating the situation which had confused biologists.[100]

The protozoanToxoplasma gondiifacilitates its transmission byinducing behavioral changesin rats through infection of neurons in theircentral nervous system.

Parasites infectsympatrichosts (those within their same geographical area) more effectively, as has been shown withdigenetic trematodesinfecting lake snails.[101]This is in line with theRed Queen hypothesis,which states that interactions between species lead to constant natural selection for coadaptation. Parasites track the locally common hosts' phenotypes, so the parasites are less infective toallopatrichosts, those from different geographical regions.[101]

Modifying host behaviour

edit
Further information:Behavior-altering parasites

Some parasitesmodify host behaviourin order to increase their transmission between hosts, often in relation to predator and prey (parasite increased trophic transmission). For example, in theCalifornia coastal salt marsh,the flukeEuhaplorchis californiensisreduces the ability of itskillifishhost to avoid predators.[102]This parasite matures inegrets,which are more likely to feed on infected killifish than on uninfected fish. Another example is the protozoanToxoplasma gondii,a parasite that matures incatsbut can be carried by many othermammals.Uninfectedratsavoid cat odors, but rats infected withT. gondiiare drawn to this scent, which may increase transmission to feline hosts.[103]The malaria parasite modifies the skin odour of its human hosts, increasing their attractiveness to mosquitoes and hence improving the chance for the parasite to be transmitted.[36]The spiderCyclosa argenteoalbaoften have parasitoid wasp larvae attached to them which alter their web-building behavior. Instead of producing their normal sticky spiral shaped webs, they made simplified webs when the parasites were attached. This manipulated behavior lasted longer and was more prominent the longer the parasites were left on the spiders.[104]

Trait loss: bedbugCimex lectulariusis flightless, like many insect ectoparasites.

Trait loss

edit

Parasites can exploit their hosts to carry out a number of functions that they would otherwise have to carry out for themselves. Parasites which lose those functions then have a selective advantage, as they can divert resources to reproduction. Many insect ectoparasites includingbedbugs,batbugs,liceandfleashave lost theirability to fly,relying instead on their hosts for transport.[105]Trait loss more generally is widespread among parasites.[106]An extreme example is themyxosporeanHenneguya zschokkei,an ectoparasite of fish and the only animal known to have lost the ability to respire aerobically: its cells lackmitochondria.[107]

Host defences

edit

Hosts have evolved a variety of defensive measures against their parasites, including physical barriers like the skin of vertebrates,[108]the immune system of mammals,[109]insects actively removing parasites,[110]and defensive chemicals in plants.[111]

The evolutionary biologistW. D. Hamiltonsuggested thatsexual reproductioncould have evolved to help to defeat multiple parasites by enablinggenetic recombination,the shuffling of genes to create varied combinations. Hamilton showed by mathematical modelling that sexual reproduction would be evolutionarily stable in different situations, and that the theory's predictions matched the actual ecology of sexual reproduction.[112][113]However, there may be a trade-off betweenimmunocompetenceand breeding male vertebrate hosts'secondary sex characteristics,such as the plumage ofpeacocksand the manes oflions.This is because the male hormonetestosteroneencourages the growth of secondary sex characteristics, favouring such males insexual selection,at the price of reducing their immune defences.[114]

Vertebrates

edit
The dryskinof vertebrates such as theshort-horned lizardprevents the entry of many parasites.

The physical barrier of the tough and often dry and waterproofskinof reptiles, birds and mammals keeps invading microorganisms from entering the body.Human skinalso secretessebum,which is toxic to most microorganisms.[108]On the other hand, larger parasites such astrematodesdetect chemicals produced by the skin to locate their hosts when they enter the water. Vertebratesalivaand tears containlysozyme,an enzyme that breaks down thecell wallsof invading bacteria.[108]Should the organism pass the mouth, thestomachwith itshydrochloric acid,toxic to most microorganisms, is the next line of defence.[108]Some intestinal parasites have a thick, tough outer coating which is digested slowly or not at all, allowing the parasite to pass through the stomach alive, at which point they enter the intestine and begin the next stage of their life. Once inside the body, parasites must overcome theimmune system'sserum proteinsandpattern recognition receptors,intracellular and cellular, that trigger the adaptive immune system'slymphocytessuch asT cellsand antibody-producingB cells.These have receptors that recognise parasites.[109]

Insects

edit
Leaf spotonoak.The spread of the parasitic fungus is limited by defensive chemicals produced by the tree, resulting in circular patches of damaged tissue.

Insects often adapt their nests to reduce parasitism. For example, one of the key reasons why the waspPolistes canadensisnests across multiplecombs,rather than building a single comb like much of the rest of its genus, is to avoid infestation bytineid moths.The tineid moth lays its eggs within the wasps' nests and then these eggs hatch into larvae that can burrow from cell to cell and prey on wasp pupae. Adult wasps attempt to remove and kill moth eggs and larvae by chewing down the edges of cells, coating the cells with an oral secretion that gives the nest a dark brownish appearance.[110]

Plants

edit

Plants respond to parasite attack with a series of chemical defences, such aspolyphenol oxidase,under the control of thejasmonic acid-insensitive (JA) andsalicylic acid(SA) signalling pathways.[111][115]The different biochemical pathways are activated by different attacks, and the two pathways can interact positively or negatively. In general, plants can either initiate a specific or a non-specific response.[115][116]Specific responses involve recognition of a parasite by the plant's cellular receptors, leading to a strong but localised response: defensive chemicals are produced around the area where the parasite was detected, blocking its spread, and avoiding wasting defensive production where it is not needed.[116]Non-specific defensive responses are systemic, meaning that the responses are not confined to an area of the plant, but spread throughout the plant, making them costly in energy. These are effective against a wide range of parasites.[116]When damaged, such as bylepidopterancaterpillars,leaves of plants includingmaizeandcottonrelease increased amounts of volatile chemicals such asterpenesthat signal they are being attacked; one effect of this is to attract parasitoid wasps, which in turn attack the caterpillars.[117]

Biology and conservation

edit

Ecology and parasitology

edit
The rescuing from extinction of theCalifornia condorwas a successful and expensive project, but itsectoparasite,the louseColpocephalum californici,was made extinct.

Parasitism and parasite evolution were until the twenty-first century studied byparasitologists,in a science dominated by medicine, rather than byecologistsorevolutionary biologists.Even though parasite-host interactions were plainly ecological and important in evolution, the history of parasitology caused what the evolutionary ecologist Robert Poulin called a "takeover of parasitism by parasitologists", leading ecologists to ignore the area. This was in his opinion "unfortunate", as parasites are "omnipresent agents of natural selection" and significant forces in evolution and ecology.[118]In his view, the long-standing split between the sciences limited the exchange of ideas, with separate conferences and separate journals. The technical languages of ecology and parasitology sometimes involved different meanings for the same words. There were philosophical differences, too: Poulin notes that, influenced by medicine, "many parasitologists accepted that evolution led to a decrease in parasite virulence, whereas modern evolutionary theory would have predicted a greater range of outcomes".[118]

Their complex relationships make parasites difficult to place in food webs: a trematode with multiple hosts for its various life cycle stages would occupy many positions in afood websimultaneously, and would set up loops of energy flow, confusing the analysis. Further, since nearly every animal has (multiple) parasites, parasites would occupy the top levels of every food web.[86]

Parasites can play a role in the proliferation of non-native species. For example, invasivegreen crabsare minimally affected by nativetrematodeson the Eastern Atlantic coast. This helps them outcompete native crabs such as theAtlantic RockandJonah crabs.[119]

Ecological parasitology can be important to attempts at control, like during thecampaign for eradicating the Guinea worm.Even though the parasite was eradicated in all but four countries, the worm began using frogs as an intermediary host before infecting dogs, making control more difficult than it would have been if the relationships had been better understood.[120]

Rationale for conservation

edit
Further information:Conservation biology of parasites
External videos
"Why you should care about parasites",14 December 2018,Knowable Magazine

Although parasites are widely considered to be harmful, the eradication of all parasites would not be beneficial. Parasites account for at least half of life's diversity; they perform important ecological roles; and without parasites, organisms might tend to asexual reproduction, diminishing the diversity of traits brought about by sexual reproduction.[121]Parasites provide an opportunity for the transfer of genetic material between species, facilitating evolutionary change.[122]Many parasites require multiple hosts of different species to complete their life cycles and rely on predator-prey or other stable ecological interactions to get from one host to another. The presence of parasites thus indicates that an ecosystem is healthy.[123]

An ectoparasite, the California condor louse,Colpocephalum californici,became a well-known conservation issue. A large and costly captive breeding program was run in the United States to rescue theCalifornia condor.It was host to a louse, which lived only on it. Any lice found were "deliberately killed" during the program, to keep the condors in the best possible health. The result was that one species, the condor, was saved and returned to the wild, while another species, the parasite, became extinct.[124]

Although parasites are often omitted in depictions offood webs,they usually occupy the top position. Parasites can function likekeystone species,reducing the dominance of superior competitors and allowingcompeting speciesto co-exist.[86][125][126]

Parasites aredistributed unevenlyamong their hosts, most hosts having no parasites, and a few hosts harbouring most of the parasite population. This distribution makes sampling difficult and requires careful use of statistics.

Quantitative ecology

edit
Further information:Aggregated distribution

A single parasite species usually has an aggregated distribution across host animals, which means that most hosts carry few parasites, while a few hosts carry the vast majority of parasite individuals. This poses considerable problems for students of parasite ecology, as it rendersparametric statisticsas commonly used by biologists invalid.Log-transformationof data before the application of parametric test, or the use ofnon-parametric statisticsis recommended by several authors, but this can give rise to further problems, so quantitative parasitology is based on more advanced biostatistical methods.[127]

History

edit

Ancient

edit
Further information:Human parasite

Human parasitesincluding roundworms, theGuinea worm,threadwormsand tapeworms are mentioned in Egyptian papyrus records from 3000 BC onwards; theEbers Papyrusdescribeshookworm.Inancient Greece,parasites including thebladder wormare described in theHippocratic Corpus,while the comic playwrightAristophanescalled tapeworms "hailstones". The Roman physicians Celsus andGalendocumented the roundwormsAscaris lumbricoidesandEnterobius vermicularis.[128]

Medieval

edit
A plate fromFrancesco Redi'sOsservazioni intorno agli animali viventi che si trovano negli animali viventi(Observations on living animals found inside living animals), 1684

In hisCanon of Medicine,completed in 1025, the Persian physicianAvicennarecorded human and animal parasites including roundworms, threadworms, the Guinea worm and tapeworms.[128]

In his 1397 bookTraité de l'état, science et pratique de l'art de la Bergerie(Account of the state, science and practice of the art of shepherding),Jehan de Brie[fr]wrote the first description of a trematode endoparasite, the sheep liver flukeFasciola hepatica.[129][130]

Early modern

edit

In theearly modern period,Francesco Redi's 1668 bookEsperienze Intorno alla Generazione degl'Insetti(Experiences of the Generation of Insects), explicitly described ecto- and endoparasites, illustratingticks,the larvae ofnasal flies of deer,andsheep liver fluke.[131]Redi noted that parasites develop from eggs, contradicting the theory ofspontaneous generation.[132]In his 1684 bookOsservazioni intorno agli animali viventi che si trovano negli animali viventi(Observations on Living Animals found in Living Animals), Redi described and illustrated over 100 parasites including thelarge roundwormin humans that causesascariasis.[131]Redi was the first to name the cysts ofEchinococcus granulosusseen in dogs and sheep as parasitic; a century later, in 1760,Peter Simon Pallascorrectly suggested that these were the larvae of tapeworms.[128]

In 1681,Antonie van Leeuwenhoekobserved and illustrated the protozoan parasiteGiardia lamblia,and linked it to "his own loose stools". This was the first protozoan parasite of humans to be seen under a microscope.[128]A few years later, in 1687, the Italian biologistsGiovanni Cosimo BonomoandDiacinto Cestonidescribedscabiesas caused by the parasitic miteSarcoptes scabiei,marking it as the first disease of humans with a known microscopic causative agent.[133]

Ronald Rosswon the 1902Nobel Prizefor showing that themalaria parasiteis transmitted by mosquitoes. This 1897 notebook page records his first observations of the parasite in mosquitoes.

Parasitology

edit
Main article:Parasitology

Modernparasitologydeveloped in the 19th century with accurate observations and experiments by many researchers and clinicians;[129]the term was first used in 1870.[134]In 1828, James Annersley describedamoebiasis,protozoal infections of the intestines and the liver, though the pathogen,Entamoeba histolytica,was not discovered until 1873 by Friedrich Lösch.James Pagetdiscovered the intestinal nematodeTrichinella spiralisin humans in 1835. James McConnell described the human liver fluke,Clonorchis sinensis,in 1875.[128]Algernon ThomasandRudolf Leuckartindependently made the first discovery of the life cycle of a trematode, the sheep liver fluke, by experiment in 1881–1883.[129]In 1877Patrick Mansondiscovered the life cycle of thefilarial wormsthat causeelephantiasistransmitted by mosquitoes. Manson further predicted that themalariaparasite,Plasmodium,had a mosquito vector, and persuadedRonald Rossto investigate. Ross confirmed that the prediction was correct in 1897–1898. At the same time,Giovanni Battista Grassiand others described the malaria parasite's life cycle stages inAnophelesmosquitoes. Ross wascontroversially awarded the 1902 Nobel prizefor his work, while Grassi was not.[128]In 1903,David Bruceidentified the protozoan parasite and thetsetse flyvector ofAfrican trypanosomiasis.[135]

Vaccine

edit
Further information:Malaria vaccine

Given the importance of malaria, with some 220 million people infected annually, many attempts have been made to interrupt its transmission. Various methods ofmalaria prophylaxishave been tried including the use ofantimalarial drugsto kill off the parasites in the blood, the eradication of its mosquito vectors withorganochlorine and other insecticides,and the development of amalaria vaccine.All of these have proven problematic, withdrug resistance,insecticide resistanceamong mosquitoes, and repeated failure of vaccines as the parasite mutates.[136]The first and as of 2015 the only licensed vaccine for any parasitic disease of humans isRTS,SforPlasmodium falciparummalaria.[137]

Biological control

edit
Further information:Biological control
Encarsia formosa,widely used ingreenhousehorticulture, was one of the first biological control agents developed.[138]

Several groups of parasites, including microbial pathogens and parasitoidal wasps have been used asbiological controlagents inagricultureandhorticulture.[139][140]

Resistance

edit
Further information:Drug resistance

Poulin observes that the widespreadprophylacticuse ofanthelmintic drugsin domestic sheep and cattle constitutes a worldwide uncontrolled experimentin the life-history evolution of their parasites. The outcomes depend on whether the drugs decrease the chance of a helminth larva reaching adulthood. If so, natural selection can be expected to favour the production of eggs at an earlier age. If on the other hand the drugs mainly affects adultparasitic worms,selection could cause delayed maturity and increasedvirulence.Such changes appear to be underway: the nematodeTeladorsagia circumcinctais changing its adult size andreproductive ratein response to drugs.[141]

Cultural significance

edit
"An Old Parasite in a New Form": an 1881Punchcartoon byEdward Linley Sambournecompares acrinolettabustle to a parasitic insect'sexoskeleton

Classical times

edit

In theclassical era,the concept of the parasite was not strictly pejorative: theparasituswas anaccepted role in Roman society,in which a person could live off the hospitality of others, in return for "flattery, simple services, and a willingness to endure humiliation".[142][143]

Society

edit
Further information:Parasitism (social offense)

Parasitism hasa derogatory sensein popular usage. According to the immunologist John Playfair,[144]

In everyday speech, the term 'parasite' is loaded with derogatory meaning. A parasite is a sponger, a lazy profiteer, a drain on society.[144]

ThesatiricalclericJonathan Swiftalludes to hyperparasitism in his 1733 poem "On Poetry: A Rhapsody", comparing poets to "vermin" who "teaze and pinch their foes":[145]

The vermin only teaze and pinch
Their foes superior by an inch.
So nat'ralists observe, a flea
Hath smaller fleas that on him prey;

And these have smaller fleas to bite 'em.
And so proceedsad infinitum.
Thus every poet, in his kind,
Is bit by him that comes behind:

A 2022 study examined the naming of some 3000 parasite species discovered in the previous two decades. Of those named after scientists, over 80% were named for men, whereas about a third of authors of papers on parasites were women. The study found that the percentage of parasite species named for relatives or friends of the author has risen sharply in the same period.[146]

Fiction

edit
Further information:List of fictional parasitesandParasites in fiction
Fictional parasitism: oil paintingParasitesby Katrin Alvarez, 2011

InBram Stoker's 1897Gothic horrornovelDracula,andits many film adaptations,the eponymousCount Draculais ablood-drinkingparasite (a vampire). The criticLaura Otisargues that as a "thief, seducer, creator, and mimic, Dracula is the ultimate parasite. The whole point of vampirism is sucking other people's blood—living at other people's expense."[147]

Disgusting and terrifyingparasitic alien speciesare widespread inscience fiction,[148][149]as for instance inRidley Scott's 1979 filmAlien.[150][151]In one scene, aXenomorphbursts out of the chest of a dead man, with blood squirting out under high pressure assisted byexplosive squibs.Animal organswere used to reinforce the shock effect. The scene was filmed in a single take, and the startled reaction of the actors was genuine.[4][152]

Theentomopathogenic fungusCordycepsis represented culturally as a deadly threat to the human race. The video game seriesThe Last of Us(2013–present) and itstelevision adaptationpresentCordycepsas a parasite of humans, causing azombie apocalypse.[153]Its human hosts initially become violent "infected" beings, before turning into blind zombie "clickers", complete with fruiting bodies growing out from their faces.[153]

See also

edit

Notes

edit
  1. ^Trophically-transmitted parasites are transmitted to their definitive host, a predator, when their intermediate host is eaten. These parasites often modify the behaviour of their intermediate hosts, causing them to behave in a way that makes them likely to be eaten, such as by climbing to a conspicuous point: this gets the parasites transmitted at the cost of the intermediate host's life.
  2. ^Thewolfis a social predator, hunting in packs; thecougaris a solitary predator, hunting alone. Neither strategy is conventionally considered parasitic.[23]

References

edit
  1. ^Poulin 2007,pp. 4–5.
  2. ^abWilson, Edward O.(2014).The Meaning of Human Existence.W. W. Norton & Company. p. 112.ISBN978-0-87140-480-0.Parasites, in a phrase, are predators that eat prey in units of less than one. Tolerable parasites are those that have evolved to ensure their own survival and reproduction but at the same time with minimum pain and cost to the host.
  3. ^Getz, W. M. (2011)."Biomass transformation webs provide a unified approach to consumer-resource modelling".Ecology Letters.14(2): 113–124.Bibcode:2011EcolL..14..113G.doi:10.1111/j.1461-0248.2010.01566.x.PMC3032891.PMID21199247.
  4. ^ab"The Making of Alien's Chestburster Scene".The Guardian.13 October 2009.Archivedfrom the original on 30 April 2010.Retrieved29 May2010.
  5. ^παράσιτος,Liddell, Henry George; Scott, Robert,A Greek–English Lexicon,on Perseus Digital Library
  6. ^παρά,Henry George Liddell, Robert Scott,A Greek–English Lexicon,on Perseus Digital Library
  7. ^σῖτος,Liddell, Henry George; Scott, Robert,A Greek–English Lexicon,on Perseus Digital Library
  8. ^σιτισμός,Liddell, Henry George; Scott, Robert,A Greek–English Lexicon,on Perseus Digital Library
  9. ^Overview of Parasitology.Australian Society of Parasitology and Australian Research Council/National Health and Medical Research Council) Research Network for Parasitology. July 2010.ISBN978-1-86499-991-4.Parasitism is a form of symbiosis, an intimate relationship between two different species. There is a biochemical interaction between host and parasite; i.e. they recognize each other, ultimately at the molecular level, and host tissues are stimulated to react in some way. This explains why parasitism may lead to disease, but not always.
  10. ^Suzuki, Sayaki U.; Sasaki, Akira (2019)."Ecological and Evolutionary Stabilities of Biotrophism, Necrotrophism, and Saprotrophism"(PDF).The American Naturalist.194(1): 90–103.Bibcode:2019ANat..194...90S.doi:10.1086/703485.ISSN0003-0147.PMID31251653.S2CID133349792.Archived(PDF)from the original on 6 March 2020.
  11. ^Rozsa, L.; Garay, J. (2023)."Definitions of parasitism, considering its potentially opposing effects at different levels of hierarchical organization".Parasitology.150(9): 761–768.doi:10.1017/S0031182023000598.PMC10478066.PMID37458178.
  12. ^"A Classification of Animal-Parasitic Nematodes".plpnemweb.ucdavis.edu.Archived fromthe originalon 6 October 2017.Retrieved25 February2016.
  13. ^Garcia, L. S. (1999)."Classification of Human Parasites, Vectors, and Similar Organisms".Clinical Infectious Diseases.29(4): 734–746.doi:10.1086/520425.PMID10589879.
  14. ^abcOverview of Parasitology.Australian Society of Parasitology and Australian Research Council/National Health and Medical Research Council) Research Network for Parasitology. July 2010.ISBN978-1-86499-991-4.
  15. ^Vecchione, Anna; Aznar, Francisco Javier (2008)."The mesoparasitic copepod Pennella balaenopterae and its significance as a visible indicator of health status in dolphins (Delphinidae): a review"(PDF).Journal of Marine Animals and Their Ecology.7(1): 4–11. Archived fromthe original(PDF)on 10 April 2018.Retrieved11 April2018.
  16. ^abcdPoulin, Robert(2011). Rollinson, D.; Hay, S. I. (eds.)."The Many Roads to Parasitism: A Tale of Convergence".Advances in Parasitology.74.Academic Press: 27–28.doi:10.1016/B978-0-12-385897-9.00001-X.ISBN978-0-12-385897-9.PMID21295676.
  17. ^"Parasitism | The Encyclopedia of Ecology and Environmental Management".Blackwell Science.Retrieved8 April2018.
  18. ^Caira, J. N.; Benz, G. W.; Borucinska, J.; Kohler, N. E. (1997)."Pugnose eels,Simenchelys parasiticus(Synaphobranchidae) from the heart of a shortfin mako,Isurus oxyrinchus(Lamnidae) ".Environmental Biology of Fishes.49(1): 139–144.Bibcode:1997EnvBF..49..139C.doi:10.1023/a:1007398609346.S2CID37865366.
  19. ^Lawrence, P. O. (1981). "Host vibration—a cue to host location by the parasite,Biosteres longicaudatus".Oecologia.48(2): 249–251.Bibcode:1981Oecol..48..249L.doi:10.1007/BF00347971.PMID28309807.S2CID6182657.
  20. ^Cardé, R. T. (2015)."Multi-cue integration: how female mosquitoes locate a human host".Current Biology.25(18): R793–R795.Bibcode:2015CBio...25.R793C.doi:10.1016/j.cub.2015.07.057.PMID26394099.
  21. ^Randle, C. P.; Cannon, B. C.; Faust, A. L.; et al. (2018). "Host Cues Mediate Growth and Establishment of Oak Mistletoe (Phoradendron leucarpum, Viscaceae), an Aerial Parasitic Plant".Castanea.83(2): 249–262.doi:10.2179/18-173.S2CID92178009.
  22. ^abcdefghijklmnoPoulin, Robert;Randhawa, Haseeb S. (February 2015)."Evolution of parasitism along convergent lines: from ecology to genomics".Parasitology.142(Suppl 1): S6–S15.doi:10.1017/S0031182013001674.PMC4413784.PMID24229807.
  23. ^abcdLafferty, K. D.; Kuris, A. M. (2002)."Trophic strategies, animal diversity and body size"(PDF).Trends in Ecology and Evolution.17(11): 507–513.doi:10.1016/s0169-5347(02)02615-0.Archived fromthe original(PDF)on 3 October 2019.
  24. ^abPoulin 2007,p. 111.
  25. ^Elumalai, V.; Viswanathan, C.; Pravinkumar, M.; Raffi, S. M. (2013)."Infestation of parasitic barnacle Sacculina spp. in commercial marine crabs".Journal of Parasitic Diseases.38(3): 337–339.doi:10.1007/s12639-013-0247-z.PMC4087306.PMID25035598.
  26. ^Cheng, Thomas C. (2012).General Parasitology.Elsevier Science. pp. 13–15.ISBN978-0-323-14010-2.
  27. ^Cox, F. E. (2001)."Concomitant infections, parasites and immune responses"(PDF).Parasitology.122. Supplement: S23–38.doi:10.1017/s003118200001698x.PMID11442193.S2CID150432.Archived(PDF)from the original on 2 December 2017.
  28. ^"Helminth Parasites".Australian Society of Parasitology.Retrieved9 October2017.
  29. ^"Pathogenic Parasitic Infections".PEOI.Retrieved18 July2013.
  30. ^Steere, A. C. (July 2001). "Lyme disease".New England Journal of Medicine.345(2): 115–125.doi:10.1056/NEJM200107123450207.PMID11450660.
  31. ^abPollitt, Laura C.; MacGregor, Paula; Matthews, Keith; Reece, Sarah E. (2011)."Malaria and trypanosome transmission: different parasites, same rules?".Trends in Parasitology.27(5): 197–203.doi:10.1016/j.pt.2011.01.004.PMC3087881.PMID21345732.
  32. ^Stevens, Alison N. P. (2010)."Predation, Herbivory, and Parasitism".Nature Education Knowledge.3(10): 36.Retrieved12 February2018.Predation, herbivory, and parasitism exist along a continuum of severity in terms of the extent to which they negatively affect an organism's fitness.... In most situations, parasites do not kill their hosts. An exception, however, occurs with parasitoids, which blur the line between parasitism and predation.
  33. ^abcdGullan, P. J.; Cranston, P. S. (2010).The Insects: An Outline of Entomology(4th ed.). Wiley. pp.308,365–367, 375, 440–441.ISBN978-1-118-84615-5.
  34. ^Wilson, Anthony J.; et al. (March 2017)."What is a vector?".Philosophical Transactions of the Royal Society B: Biological Sciences.372(1719): 20160085.doi:10.1098/rstb.2016.0085.PMC5352812.PMID28289253.
  35. ^abGodfrey, Stephanie S. (December 2013)."Networks and the ecology of parasite transmission: A framework for wildlife parasitology".Wildlife.2:235–245.Bibcode:2013IJPPW...2..235G.doi:10.1016/j.ijppaw.2013.09.001.PMC3862525.PMID24533342.
  36. ^abde Boer, Jetske G.; Robinson, Ailie; Powers, Stephen J.; Burgers, Saskia L. G. E.; Caulfield, John C.; Birkett, Michael A.; Smallegange, Renate C.; van Genderen, Perry J. J.; Bousema, Teun; Sauerwein, Robert W.; Pickett, John A.; Takken, Willem; Logan, James G. (August 2017)."Odours of Plasmodium falciparum-infected participants influence mosquito–host interactions".Scientific Reports.7(1): 9283.Bibcode:2017NatSR...7.9283D.doi:10.1038/s41598-017-08978-9.PMC5570919.PMID28839251.
  37. ^abDissanaike, A. S. (1957). "On Protozoa hyperparasitic in Helminth, with some observations onNosema helminthorumMoniez, 1887 ".Journal of Helminthology.31(1–2): 47–64.doi:10.1017/s0022149x00033290.PMID13429025.S2CID35487084.
  38. ^abThomas, J. A.; Schönrogge, K.; Bonelli, S.; Barbero, F.; Balletto, E. (2010)."Corruption of ant acoustical signals by mimetic social parasites:Maculineabutterflies achieve elevated status in host societies by mimicking the acoustics of queen ants ".Commun Integr Biol.3(2): 169–171.doi:10.4161/cib.3.2.10603.PMC2889977.PMID20585513.
  39. ^abPayne, R. B. (1997)."Avian brood parasitism".In Clayton, D. H.; Moore, J. (eds.).Host–parasite evolution: General principles and avian models.Oxford University Press. pp.338–369.ISBN978-0-19-854892-8.
  40. ^abSlater, Peter J. B.; Rosenblatt, Jay S.; Snowdon, Charles T.; Roper, Timothy J.;Brockmann, H. Jane;Naguib, Marc (30 January 2005).Advances in the Study of Behavior.Academic Press. p. 365.ISBN978-0-08-049015-1.
  41. ^abPietsch, Theodore W. (25 August 2005). "Dimorphism, parasitism, and sex revisited: modes of reproduction among deep-sea ceratioid anglerfishes (Teleostei: Lophiiformes)".Ichthyological Research.52(3): 207–236.Bibcode:2005IchtR..52..207P.doi:10.1007/s10228-005-0286-2.S2CID24768783.
  42. ^abRochat, Jacques; Gutierrez, Andrew Paul (May 2001)."Weather-mediated regulation of olive scale by two parasitoids".Journal of Animal Ecology.70(3): 476–490.Bibcode:2001JAnEc..70..476R.doi:10.1046/j.1365-2656.2001.00505.x.S2CID73607283.
  43. ^Askew, R. R. (1961)."On the Biology of the Inhabitants of Oak Galls of Cynipidae (Hymenoptera) in Britain".Transactions of the Society for British Entomology.14:237–268.
  44. ^Parratt, Steven R.; Laine, Anna-Liisa (January 2016)."The role of hyperparasitism in microbial pathogen ecology and evolution".The ISME Journal.10(8): 1815–1822.Bibcode:2016ISMEJ..10.1815P.doi:10.1038/ismej.2015.247.PMC5029149.PMID26784356.
  45. ^Van Oystaeyen, Annette; Araujo Alves, Denise; Caliari Oliveira, Ricardo; Lima do Nascimento, Daniela; Santos do Nascimento, Fábio; Billen, Johan; Wenseleers, Tom (September 2013). "Sneaky queens inMeliponabees selectively detect and infiltrate queenless colonies ".Animal Behaviour.86(3): 603–609.CiteSeerX10.1.1.309.6081.doi:10.1016/j.anbehav.2013.07.001.S2CID12921696.
  46. ^"Social Parasites in the Ant Colony".Antkeepers.Retrieved4 April2016.
  47. ^Emery, Carlo (1909). "Über den Ursprung der dulotischen, parasitischen un myrmekophilen Ameisen".Biologischen Centralblatt.29:352–362.
  48. ^Deslippe, Richard (2010)."Social Parasitism in Ants".Nature Education Knowledge.Retrieved29 October2010.
  49. ^Emery, C. (1909)."Über den Ursprung der dulotischen, parasitischen und myrmekophilen Ameisen".Biologisches Centralblatt.29:352–362.
  50. ^Bourke, Andrew F. G.; Franks, Nigel R. (July 1991). "Alternative adaptations, sympatric speciation and the evolution of parasitic, inquiline ants".Biological Journal of the Linnean Society.43(3): 157–178.doi:10.1111/j.1095-8312.1991.tb00591.x.ISSN0024-4066.
  51. ^O'Brien, Timothy G. (1988). "Parasitic nursing behavior in the wedge-capped capuchin monkey (Cebus olivaceus) ".American Journal of Primatology.16(4): 341–344.doi:10.1002/ajp.1350160406.PMID32079372.S2CID86176932.
  52. ^Payne, R. B. (15 September 2005).The Cuckoos(1st ed.). Oxford: Oxford University Press.ISBN9780198502135.{{cite book}}:CS1 maint: date and year (link)
  53. ^Rothstein, S. I. (1990). "A model system for coevolution: avian brood parasitism".Annual Review of Ecology and Systematics.21:481–508.doi:10.1146/annurev.ecolsys.21.1.481.
  54. ^De Marsico, M. C.; Gloag, R.; Ursino, C. A.; Reboreda, J. C. (March 2013)."A novel method of rejection of brood parasitic eggs reduces parasitism intensity in a cowbird host".Biology Letters.9(3): 20130076.doi:10.1098/rsbl.2013.0076.PMC3645041.PMID23485877.
  55. ^Welbergen, J.; Davies, N. B. (2011)."A parasite in wolf's clothing: hawk mimicry reduces mobbing of cuckoos by hosts".Behavioral Ecology.22(3): 574–579.doi:10.1093/beheco/arr008.
  56. ^Yang, C., X. Si, W. Liang, and A. P. Møller (2020)."Spatial variation in egg polymorphism among cuckoo hosts across 4 continents".Current Zoology.66(5): 477–483.doi:10.1093/cz/zoaa011.PMC7705517.PMID33293928– via Oxford Academic.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  57. ^Furness, R. W. (1978). "Kleptoparasitism by great skuas (Catharacta skuaBrünn.) and Arctic skuas (Stercorarius parasiticusL.) at a Shetland seabird colony ".Animal Behaviour.26:1167–1177.doi:10.1016/0003-3472(78)90107-0.S2CID53155057.
  58. ^Maggenti, Armand R.; Maggenti, Mary Ann; Gardner, Scott Lyell (2005).Online Dictionary of Invertebrate Zoology(PDF).University of Nebraska. p. 22. Archived fromthe original(PDF)on 18 April 2018.
  59. ^"Featured Creatures.Encarsia perplexa".University of Florida.Retrieved6 January2018.
  60. ^Berec, Ludek; Schembri, Patrick J.; Boukal, David S. (2005)."Sex determination inBonellia viridis(Echiura: Bonelliidae): population dynamics and evolution "(PDF).Oikos.108(3): 473–484.Bibcode:2005Oikos.108..473B.doi:10.1111/j.0030-1299.2005.13350.x.Archived(PDF)from the original on 3 October 2019.
  61. ^Rollinson, D.; Hay, S. I. (2011).Advances in parasitology.Oxford: Elsevier Science. pp. 4–7.ISBN978-0-12-385897-9.
  62. ^abPoulin 2007,p. 6.
  63. ^Polaszek, Andrew; Vilhemsen, Lars (2023)."Biodiversity of hymenopteran parasitoids".Current Opinion in Insect Science.56:101026.Bibcode:2023COIS...5601026P.doi:10.1016/j.cois.2023.101026.PMID36966863.S2CID257756440.
  64. ^Forbes, Andrew A.; Bagley, Robin K.; Beer, Marc A.; et al. (12 July 2018)."Quantifying the unquantifiable: why Hymenoptera, not Coleoptera, is the most speciose animal order".BMC Ecology.18(1): 21.Bibcode:2018BMCE...18...21F.doi:10.1186/s12898-018-0176-x.ISSN1472-6785.PMC6042248.PMID30001194.
  65. ^Morand, Serge; Krasnov, Boris R.; Littlewood, D. Timothy J. (2015).Parasite Diversity and Diversification.Cambridge University Press. p. 44.ISBN978-1-107-03765-6.
  66. ^Rastogi, V. B. (1997).Modern Biology.Pitambar Publishing. p. 115.ISBN978-81-209-0496-5.
  67. ^Kokla, Anna; Melnyk, Charles W. (1 October 2018). "Developing a thief: Haustoria formation in parasitic plants".Developmental Biology.442(1): 53–59.doi:10.1016/j.ydbio.2018.06.013.ISSN0012-1606.PMID29935146.S2CID49394142.
  68. ^abcHeide-Jørgensen, Henning S. (2008).Parasitic flowering plants.Brill.ISBN978-90-04-16750-6.
  69. ^Nickrent, Daniel L.(2002)."Parasitic Plants of the World"(PDF).Archived(PDF)from the original on 6 March 2016.Retrieved10 April2018.which appeared in Spanish as Chapter 2, pp. 7–27 in: J. A. López-Sáez, P. Catalán and L. Sáez [eds.],Parasitic Plants of the Iberian Peninsula and Balearic Islands.
  70. ^Nickrent, D. L.; Musselman, L. J. (2004). "Introduction to Parasitic Flowering Plants".The Plant Health Instructor.doi:10.1094/PHI-I-2004-0330-01.
  71. ^Westwood, James H.; Yoder, John I.; Timko, Michael P.; dePamphilis, Claude W. (2010). "The evolution of parasitism in plants".Trends in Plant Science.15(4): 227–235.Bibcode:2010TPS....15..227W.doi:10.1016/j.tplants.2010.01.004.PMID20153240.
  72. ^Leake, J. R. (1994). "The biology of myco-heterotrophic ('saprophytic') plants".New Phytologist.127(2): 171–216.Bibcode:1994NewPh.127..171L.doi:10.1111/j.1469-8137.1994.tb04272.x.PMID33874520.S2CID85142620.
  73. ^Fei, Wang; Liu, Ye (11 August 2022)."Biotrophic Fungal Pathogens: a Critical Overview".Applied Biochemistry and Biotechnology.195(1): 1–16.doi:10.1007/s12010-022-04087-0.ISSN0273-2289.PMID35951248.S2CID251474576.
  74. ^"What is honey fungus?".Royal Horticultural Society.Retrieved12 October2017.
  75. ^Chowdhury, Supriyo; Basu, Arpita; Kundu, Surekha (8 December 2017)."Biotrophy-necrotrophy switch in pathogen evoke differential response in resistant and susceptible sesame involving multiple signaling pathways at different phases".Scientific Reports.7(1): 17251.Bibcode:2017NatSR...717251C.doi:10.1038/s41598-017-17248-7.ISSN2045-2322.PMC5722813.PMID29222513.
  76. ^"Stop neglecting fungi".Nature Microbiology.2(8): 17120. 25 July 2017.doi:10.1038/nmicrobiol.2017.120.PMID28741610.
  77. ^Didier, E. S.; Stovall, M. E.; Green, L. C.; Brindley, P. J.; Sestak, K.; Didier, P. J. (9 December 2004)."Epidemiology of microsporidiosis: sources and modes of transmission".Veterinary Parasitology.126(1–2): 145–166.doi:10.1016/j.vetpar.2004.09.006.PMID15567583.
  78. ^Esch, K. J.; Petersen, C. A. (January 2013)."Transmission and epidemiology of zoonotic protozoal diseases of companion animals".Clinical Microbiology Reviews.26(1): 58–85.doi:10.1128/CMR.00067-12.PMC3553666.PMID23297259.
  79. ^McFall-Ngai, Margaret (January 2007)."Adaptive Immunity: Care for the community".Nature.445(7124): 153.Bibcode:2007Natur.445..153M.doi:10.1038/445153a.PMID17215830.S2CID9273396.
  80. ^Fisher, Bruce; Harvey, Richard P.; Champe, Pamela C. (2007).Lippincott's Illustrated Reviews: Microbiology (Lippincott's Illustrated Reviews Series).Lippincott Williams & Wilkins. pp. 332–353.ISBN978-0-7817-8215-9.
  81. ^Koonin, E. V.; Senkevich, T. G.; Dolja, V. V. (2006)."The ancient Virus World and evolution of cells".Biology Direct.1:29.doi:10.1186/1745-6150-1-29.PMC1594570.PMID16984643.
  82. ^Breitbart, M.;Rohwer, F. (2005). "Here a virus, there a virus, everywhere the same virus?".Trends in Microbiology.13(6): 278–284.doi:10.1016/j.tim.2005.04.003.PMID15936660.
  83. ^Lawrence, C. M.; Menon, S.; Eilers, B. J.; et al. (2009)."Structural and functional studies of archaeal viruses".The Journal of Biological Chemistry.284(19): 12599–603.doi:10.1074/jbc.R800078200.PMC2675988.PMID19158076.
  84. ^Edwards, R. A.; Rohwer, F. (2005)."Viral metagenomics"(PDF).Nature Reviews Microbiology.3(6): 504–510.doi:10.1038/nrmicro1163.PMID15886693.S2CID8059643.Archived(PDF)from the original on 3 October 2019.
  85. ^abDobson, A.; Lafferty, K. D.; Kuris, A. M.; Hechinger, R. F.; Jetz, W. (2008)."Homage to Linnaeus: How many parasites? How many hosts?".Proceedings of the National Academy of Sciences.105(Supplement 1): 11482–11489.Bibcode:2008PNAS..10511482D.doi:10.1073/pnas.0803232105.PMC2556407.PMID18695218.
  86. ^abcSukhdeo, Michael V.K. (2012)."Where are the parasites in food webs?".Parasites & Vectors.5(1): 239.doi:10.1186/1756-3305-5-239.PMC3523981.PMID23092160.
  87. ^Wolff, Ewan D. S.; Salisbury, Steven W.; Horner, John R.; Varrichio, David J. (2009)."Common Avian Infection Plagued the Tyrant Dinosaurs".PLOS ONE.4(9): e7288.Bibcode:2009PLoSO...4.7288W.doi:10.1371/journal.pone.0007288.PMC2748709.PMID19789646.
  88. ^Ponomarenko, A.G. (1976) A new insect from the Cretaceous of Transbaikalia, a possible parasite of pterosaurians.Paleontological Journal10(3):339-343 (English) /Paleontologicheskii Zhurnal1976(3):102-106 (Russian)
  89. ^Zhang, Yanjie; Shih, Chungkun; Rasnitsyn, Alexandr; Ren, Dong; Gao, Taiping (2020)."A new flea from the Early Cretaceous of China".Acta Palaeontologica Polonica.65.doi:10.4202/app.00680.2019.
  90. ^Thanit Nonsrirach, Serge Morand, Alexis Ribas, Sita Manitkoon, Komsorn Lauprasert, Julien Claude (9 August 2023)."First discovery of parasite eggs in a vertebrate coprolite of the Late Triassic in Thailand".PLOS ONE.18(8): e0287891.Bibcode:2023PLoSO..1887891N.doi:10.1371/journal.pone.0287891.PMC10411797.PMID37556448.{{cite journal}}:CS1 maint: multiple names: authors list (link)
  91. ^abRook, G. A. (2007)."The hygiene hypothesis and the increasing prevalence of chronic inflammatory disorders".Transactions of the Royal Society of Tropical Medicine and Hygiene.101(11): 1072–1074.doi:10.1016/j.trstmh.2007.05.014.PMID17619029.
  92. ^abcMassey, R. C.;Buckling, A.; ffrench-Constant, R. (2004)."Interference competition and parasite virulence".Proceedings of the Royal Society B: Biological Sciences.271(1541): 785–788.doi:10.1098/rspb.2004.2676.PMC1691666.PMID15255095.
  93. ^Ewald, Paul W. (1994).Evolution of Infectious Disease.Oxford University Press. p. 8.ISBN978-0-19-534519-3.
  94. ^Werren, John H. (February 2003)."Invasion of the Gender Benders: by manipulating sex and reproduction in their hosts, many parasites improve their own odds of survival and may shape the evolution of sex itself".Natural History.112(1): 58.OCLC1759475.Archived fromthe originalon 8 July 2012.Retrieved15 November2008.
  95. ^Margulis, Lynn;Sagan, Dorion;Eldredge, Niles(1995).What Is Life?.Simon and Schuster.ISBN978-0-684-81087-4.
  96. ^Sarkar, Sahotra; Plutynski, Anya (2008).A Companion to the Philosophy of Biology.John Wiley & Sons. p. 358.ISBN978-0-470-69584-5.
  97. ^Rigaud, T.; Perrot-Minnot, M.-J.; Brown, M. J. F. (2010)."Parasite and host assemblages: embracing the reality will improve our knowledge of parasite transmission and virulence".Proceedings of the Royal Society B: Biological Sciences.277(1701): 3693–3702.doi:10.1098/rspb.2010.1163.PMC2992712.PMID20667874.
  98. ^Page, Roderic D. M. (27 January 2006). "Cospeciation".Encyclopedia of Life Sciences.John Wiley.doi:10.1038/npg.els.0004124.ISBN978-0-470-01617-6.
  99. ^Switzer, William M.; Salemi, Marco; Shanmugam, Vedapuri; et al. (2005)."Ancient co-speciation of simian foamy viruses and primates".Nature.434(7031): 376–380.Bibcode:2005Natur.434..376S.doi:10.1038/nature03341.PMID15772660.S2CID4326578.
  100. ^Johnson, K. P.; Kennedy, M.; McCracken, K. G (2006)."Reinterpreting the origins of flamingo lice: cospeciation or host-switching?".Biology Letters.2(2): 275–278.doi:10.1098/rsbl.2005.0427.PMC1618896.PMID17148381.
  101. ^abLively, C. M.; Dybdahl, M. F. (2000)."Parasite adaptation to locally common host genotypes"(PDF).Nature.405(6787): 679–81.Bibcode:2000Natur.405..679L.doi:10.1038/35015069.PMID10864323.S2CID4387547.Archived(PDF)from the original on 7 June 2016.
  102. ^Lafferty, K. D.; Morris, A. K. (1996)."Altered behavior of parasitized killifish increases susceptibility to predation by bird final hosts"(PDF).Ecology.77(5): 1390–1397.Bibcode:1996Ecol...77.1390L.doi:10.2307/2265536.JSTOR2265536.Archived(PDF)from the original on 3 March 2019.
  103. ^Berdoy, M.; Webster, J. P.; Macdonald, D. W. (2000)."Fatal attraction in rats infected withToxoplasma gondii".Proc. Biol. Sci.267(1452): 1591–4.doi:10.1098/rspb.2000.1182.PMC1690701.PMID11007336.
  104. ^Takasuka, Keizo (16 September 2019)."Evaluation of manipulative effects by an ichneumonid spider-ectoparasitoid larva upon an orb-weaving spider host (Araneidae: Cyclosa argenteoalba) by means of surgical removal and transplantation".The Journal of Arachnology.47(2): 181.doi:10.1636/joa-s-18-082.ISSN0161-8202.S2CID202579182.
  105. ^Alexander, David E. (2015).On the Wing: Insects, Pterosaurs, Birds, Bats and the Evolution of Animal Flight.Oxford University Press. p. 119.ISBN978-0-19-999679-7.
  106. ^Poulin, Robert(September 1995)."Evolution of parasite life history traits: myths and reality"(PDF).Parasitology Today.11(9): 342–345.doi:10.1016/0169-4758(95)80187-1.PMID15275316.Archived fromthe original(PDF)on 16 February 2012.
  107. ^Yahalom, Dayana; Atkinson, Stephen D.; Neuhof, Moran; Chang, E. Sally; Philippe, Hervé; Cartwright, Paulyn; Bartholomew, Jerri L.; Huchon, Dorothée (19 February 2020)."A cnidarian parasite of salmon (Myxozoa: Henneguya) lacks a mitochondrial genome".Proceedings of the National Academy of Sciences.117(10): 5358–5363.Bibcode:2020PNAS..117.5358Y.doi:10.1073/pnas.1909907117.PMC7071853.PMID32094163.
  108. ^abcd"Host–Parasite Interactions Innate Defenses of the Host"(PDF).University of Colorado. Archived fromthe original(PDF)on 4 March 2016.Retrieved7 May2014.
  109. ^abMaizels, R. M. (2009)."Parasite immunomodulation and polymorphisms of the immune system".J. Biol.8(7): 62.doi:10.1186/jbiol166.PMC2736671.PMID19664200.
  110. ^abJeanne, Robert L. (1979)."Construction and Utilization of Multiple Combs in Polistes canadensis in Relation to the Biology of a Predaceous Moth".Behavioral Ecology and Sociobiology.4(3): 293–310.Bibcode:1979BEcoS...4..293J.doi:10.1007/bf00297649.S2CID36132488.
  111. ^abRunyon, J. B.; Mescher, M. C.; De Moraes, C. M. (2010)."Plant defenses against parasitic plants show similarities to those induced by herbivores and pathogens".Plant Signal Behav.5(8): 929–31.Bibcode:2010PlSiB...5..929R.doi:10.4161/psb.5.8.11772.PMC3115164.PMID20495380.
  112. ^Hamilton, W. D.;Axelrod, R.; Tanese, R. (May 1990)."Sexual reproduction as an adaptation to resist parasites (a review)".Proceedings of the National Academy of Sciences.87(9): 3566–3573.Bibcode:1990PNAS...87.3566H.doi:10.1073/pnas.87.9.3566.PMC53943.PMID2185476.
  113. ^Ebert, Dieter;Hamilton, William D.(1996). "Sex against virulence: the coevolution of parasitic diseases".Trends in Ecology & Evolution.11(2): 79–82.Bibcode:1996TEcoE..11...79E.doi:10.1016/0169-5347(96)81047-0.PMID21237766.
  114. ^Folstad, Ivar; Karter, Andrew John (1992)."Parasites, Bright Males, and the Immunocompetence Handicap".The American Naturalist.139(3): 603–622.Bibcode:1992ANat..139..603F.doi:10.1086/285346.S2CID85266542.[permanent dead link‍]
  115. ^abThaler, Jennifer S.; Karban, Richard; Ullman, Diane E.; Boege, Karina; Bostock, Richard M. (2002)."Cross-talk between jasmonate and salicylate plant defense pathways: effects on several plant parasites".Oecologia.131(2): 227–235.Bibcode:2002Oecol.131..227T.doi:10.1007/s00442-002-0885-9.PMID28547690.S2CID25912204.
  116. ^abcFrank, S. A. (2000)."Specific and non-specific defense against parasitic attack"(PDF).J. Theor. Biol.202(4): 283–304.Bibcode:2000JThBi.202..283F.CiteSeerX10.1.1.212.7024.doi:10.1006/jtbi.1999.1054.PMID10666361.Archived(PDF)from the original on 14 June 2001.
  117. ^Paré, Paul W.; Tumlinson, James H. (1 October 1999)."Plant Volatiles as a Defense against Insect Herbivores".Plant Physiology.121(2): 325–332.doi:10.1104/pp.121.2.325.PMC1539229.PMID10517823.
  118. ^abPoulin 2007,pp. x, 1–2.
  119. ^Blakeslee, April M. H.; Keogh, Carolyn L.; Fowler, Amy E.; Griffen, Blaine D.; Todd, Peter Alan (1 June 2015)."Assessing the Effects of Trematode Infection on Invasive Green Crabs in Eastern North America".PLOS ONE.10(6): e0128674.Bibcode:2015PLoSO..1028674B.doi:10.1371/journal.pone.0128674.PMC4451766.PMID26030816.
  120. ^Eberhard, M. L. (August 2016)."Possible Role of Fish and Frogs as Paratenic Hosts of Dracunculus medinensis, Chad".Emerging Infectious Diseases.22(8): 1428–1430.doi:10.3201/eid2208.160043.PMC4982183.PMID27434418.
  121. ^Holt, R. D. (2010)."IJEE Soapbox: World free of parasites and vectors: Would it be heaven, or would it be hell?"(PDF).Israel Journal of Ecology and Evolution.56(3): 239–250.doi:10.1560/IJEE.56.3-4.239.Archived(PDF)from the original on 8 September 2015.
  122. ^Combes, Claude (2005).The Art of being a Parasite.University of Chicago Press.ISBN978-0-226-11438-5.
  123. ^Hudson, Peter J.; Dobson, Andrew P.; Lafferty, Kevin D. (2006)."Is a healthy ecosystem one that is rich in parasites?"(PDF).Trends in Ecology & Evolution.21(7): 381–385.doi:10.1016/j.tree.2006.04.007.PMID16713014.Archived fromthe original(PDF)on 10 August 2017.
  124. ^Stringer, Andrew Paul; Linklater, Wayne (2014)."Everything in Moderation: Principles of Parasite Control for Wildlife Conservation".BioScience.64(10): 932–937.doi:10.1093/biosci/biu135.
  125. ^Lafferty, Kevin D.; Allesina, Stefano; Arim, Matias; Briggs, Cherie J.; et al. (2008)."Parasites in food webs: the ultimate missing links".Ecology Letters.11(6): 533–546.Bibcode:2008EcolL..11..533L.doi:10.1111/j.1461-0248.2008.01174.x.PMC2408649.PMID18462196.
  126. ^Chase, Jonathan (2013)."Parasites in Food Webs: Untangling the Entangled Bank".PLOS Biology.11(6): e1001580.doi:10.1371/journal.pbio.1001580.PMC3678997.PMID23776405.
  127. ^Rózsa, L.; Reiczigel, J.; Majoros, G. (2000)."Quantifying parasites in samples of hosts"(PDF).J. Parasitol.86(2): 228–32.doi:10.1645/0022-3395(2000)086[0228:QPISOH]2.0.CO;2.PMID10780537.S2CID16228008.Archived fromthe original(PDF)on 19 June 2018.
  128. ^abcdefCox, Francis E. G. (June 2004). "History of human parasitic diseases".Infectious Disease Clinics of North America.18(2): 173–174.doi:10.1016/j.idc.2004.01.001.PMID15145374.
  129. ^abcCheng, Thomas C. (1973).General Parasitology.Academic Press. pp. 120–134.ISBN978-0-12-170750-7.The 19th century might be thought of as the genesis of modern parasitology.
  130. ^Humphrey-Smith, Ian, ed. (1993).Sept siècles de parasitologie en France[The French School of Parasitology] (in French). Société Française de Parasitologie. pp. 26–29.
  131. ^abIoli, A.; Petithory, J. C.; Theodorides, J. (1997). "Francesco Redi and the birth of experimental parasitology".Hist Sci Med.31(1): 61–66.PMID11625103.
  132. ^Bush, A. O.; Fernández, J. C.; Esch, G. W.; Seed, J. R. (2001).Parasitism: The Diversity and Ecology of Animal Parasites.Cambridge University Press. p.4.ISBN978-0-521-66447-9.
  133. ^"Acarus as the cause of scabies".University of Cagliari.Retrieved11 April2018.
  134. ^"Parasitology".Merriam-Webster.Retrieved13 April2018.
  135. ^Ellis, Harold(March 2006). "Sir David Bruce, a pioneer of tropical medicine".British Journal of Hospital Medicine.67(3): 158.doi:10.12968/hmed.2006.67.3.20624.PMID16562450.
  136. ^"Malaria and Malaria Vaccine Candidates".The College of Physicians of Philadelphia. 19 April 2017.Retrieved11 February2018.
  137. ^Walsh, Fergus(24 July 2015)."Malaria vaccine gets 'green light'".BBC.Retrieved25 July2015.
  138. ^Hoddle, M. S.; Van Driesche, R. G.; Sanderson, J. P. (1998). "Biology and Use of the Whitefly Parasitoid Encarsia Formosa".Annual Review of Entomology.43:645–669.doi:10.1146/annurev.ento.43.1.645.PMID15012401.
  139. ^"Parasitoid Wasps (Hymenoptera)".University of Maryland.Archivedfrom the original on 27 August 2016.Retrieved6 June2016.
  140. ^Encouraging innovation in biopesticide development.Archived15 May 2012 at theWayback MachineEuropean Commission (2008). Accessed on 9 January 2017
  141. ^Poulin 2007,pp. 265–266.
  142. ^Matyszak, Philip (2017).24 Hours in Ancient Rome: A Day in the Life of the People Who Lived There.Michael O'Mara. p. 252.ISBN978-1-78243-857-1.
  143. ^Damon, Cynthia (1997)."5".The Mask of the Parasite: A Pathology of Roman Patronage.University of Michigan Press. p. 148.ISBN978-0-472-10760-5.A satirist seeking to portray client misery naturally focuses on the relationship with the greatest dependency, that in which a client gets his food from his patron, and for this the prefabricated persona of the parasite proved itself extremely useful.
  144. ^abPlayfair, John (2007).Living with Germs: In health and disease.Oxford University Press. p. 19.ISBN978-0-19-157934-9.Playfair is comparing the popular usage to a biologist's view of parasitism, which he calls (heading the same page) "an ancient and respectable view of life".
  145. ^Swift, Jonathan(1733).On Poetry: A Rapsody.And sold by J. Huggonson, next to Kent's Coffee-house, near Serjeant's-inn, in Chancery-lane; [and] at the bookseller's and pamphletshops.
  146. ^Poulin, Robert;McDougall, Cameron; Presswell, Bronwen (11 May 2022)."What's in a name? Taxonomic and gender biases in the etymology of new species names".Proceedings of the Royal Society B: Biological Sciences.289(1974).doi:10.1098/rspb.2021.2708.PMC9091844.PMID35538778.
  147. ^Otis, Laura (2001).Networking: Communicating with Bodies and Machines in the Nineteenth Century.University of Michigan Press. p. 216.ISBN978-0-472-11213-5.
  148. ^"Parasitism and Symbiosis".The Encyclopedia of Science Fiction.10 January 2016.
  149. ^Dove, Alistair (9 May 2011)."This is clearly an important species we're dealing with".Deep Sea News.
  150. ^Pappas, Stephanie (29 May 2012)."5 Alien Parasites and Their Real-World Counterparts".Live Science.
  151. ^Sercel, Alex (19 May 2017)."Parasitism in the Alien Movies".Signal to Noise Magazine. Archived fromthe originalon 26 March 2023.Retrieved11 February2018.
  152. ^Nordine, Michael (25 April 2017)."'Alien' Evolution: Explore Every Stage in the Xenomorph's Gruesome Life Cycle. Celebrate Alien Day with a look at the past, present and future of cinema's most terrifying extraterrestrial ".IndieWire.
  153. ^abHill, Kyle (25 June 2013)."The Fungus that Reduced Humanity to The Last of Us".Scientific American.Retrieved4 May2021.

Sources

edit

Further reading

edit
edit
Wikimedia Commons has media related toParasites.
Wikibooks has more on the topic of:Parasitism
Retrieved from "https://en.wikipedia.org/w/index.php?title=Parasitism&oldid=1259606707"