Parasitoid - AbsoluteAstronomy.com

A parasitoid is an organism that spends a significant portion of its life history

Biological life cycle

A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

attached to or within a single host

Host (biology)

In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...

organism

Organism

In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...

in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host. Thus parasitoids are similar to typical parasites except in the more dire prognosis

Prognosis

Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...

for the host

Host (biology)

Definitions and distinctions

The term parasitoid was coined in 1913 by the German writer O. M. Reuter (and adopted in English by his reviewer, William Morton Wheeler

William Morton Wheeler

William Morton Wheeler, Ph.D. was an American entomologist, myrmecologist and Harvard professor.-Early life:...

) to describe the strategy in which, during its development, the parasite lives in or on the body of a single host individual, eventually killing that host, the adult parasitoid being free-living. Since that time however, the concept has been variously generalised and widely applied.

In practice it is not always necessary to distinguish parasitoidy from parasitism, nor is it always even possible to do so cleanly. However, when it is appropriate to do so, a typically parasitic relationship is one in which parasite and host interact without lethal harm to the host, and without dramatically reducing the host's reproductive success

Reproductive success

Reproductive success is defined as the passing of genes onto the next generation in a way that they too can pass those genes on. In practice, this is often a tally of the number of offspring produced by an individual. A more correct definition, which incorporates inclusive fitness, is the...

. In most such relationships, the parasite arrogates enough nutrient

Nutrient

A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...

s or other resource

Resource

A resource is a source or supply from which benefit is produced, typically of limited availability.Resource may also refer to:* Resource , substances or objects required by a biological organism for normal maintenance, growth, and reproduction...

s to thrive without preventing the host from reproducing. In contrast, in a parasitoidal relationship the exploiting organism kills or sterilises

Sterility (physiology)

Sterility is the physiological inability to effect sexual reproduction in a living thing, members of whose kind have been produced sexually. The term may be used in reference to* types of organism, such as the mule, a sterile hybrid;...

the host, typically before it can produce offspring. A non-lethal parasite sometimes is termed a biotroph

Parasitism

Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

. In contrast, when a parasitoidal relationship is regarded as a form of parasitism

Parasitism

, the parasitoid may be called a necrotroph

Parasitism

.

When an organism sterilises its host without directly killing it, then whether to term it a parasitoid or a parasite, is a matter of context and preference. Often for a parasite to prevent reproduction of the host is incidental, but various forms of systematic parasitic castration

Parasitic castration

Parasitic castration is the strategy, by a parasite, of blocking reproduction by its host, completely or in part. For example, Hemioniscus balani, a parasitic castrator of hermaphroditic barnacles, feeds on ovarian fluid, so that its host loses female reproductive ability but still can function as...

occur among parasitoids, and many such biological strategies

Evolutionarily stable strategy

In game theory and behavioural ecology, an evolutionarily stable strategy , which is sometimes also called an evolutionary stable strategy, is a strategy which, if adopted by a population of players, cannot be invaded by any alternative strategy that is initially rare. An ESS is an equilibrium...

are highly sophisticated. Crustacean parasites or parasitoids include several impressive examples.

Protelean

Protelean

Protelean organisms are those that begin the growing phase of their lives as parasites, and in particular, typically as internal parasites. As a rule they end that phase of their lives parasitoidally by killing or consuming the host, and then they emerge as free-living adults.-Functional...

is a term that various authors use to denote

Denotation

This word has distinct meanings in other fields: see denotation . For the opposite of Denotation see Connotation.*In logic, linguistics and semiotics, the denotation of a word or phrase is a part of its meaning; however, the part referred to varies by context:** In grammar and literary theory, the...

organisms that live as parasites only during the early, growing, phases of their lives; typically they then begin by behaving as internal parasites; also typically they end that phase of their lives parasitoidally by killing or consuming the host. Finally they emerge as free-living adults, with or without an intervening phase of diapause

Diapause

Diapause is the delay in development in response to regularly and recurring periods of adverse environmental conditions. It is considered to be a physiological state of dormancy with very specific initiating and inhibiting conditions...

or metamorphosis

Metamorphosis

Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation...

.

Protelean organisms are widely regarded as a special class of parasites, or more usually parasitoids. The most typical examples of proteleans are the parasitoidal Hymenoptera

Hymenoptera

Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...

, Diptera

Diptera

Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...

, Strepsiptera

Strepsiptera

The Strepsiptera are an order of insects with ten families making up about 600 species...

, and some other insects. Usually such insects are holometabolous

Endopterygota

The Endopterygota, also known as Holometabola, are insects of the subclass Pterygota which go through distinctive larval, pupal, and adult stages. They undergo a radical metamorphosis, with the larval and adult stages differing considerably in their structure and behaviour...

. It is reasonable to regard holometaboly as preadaptation

Exaptation

Exaptation, cooption, and preadaptation are related terms referring to shifts in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common in both anatomy and behaviour...

for the protelean life history

Biological life cycle

A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

because it implies that their larval stage of life differs drastically from the adult stage, both functionally and morphologically.

Idiobiont parasitoids are those that prevent further development of the host after initial parasitization; typically they attack a host life stage that is immobile (e.g., an egg or pupa

Pupa

A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...

), and almost without exception idiobiont parasitoids live outside the host. Koinobiont parasitoids allow the host to continue its development and often do not kill or consume the host until the host either is about to pupate or become an adult; this therefore typically involves living within an active, mobile host. In turn, koinobionts can be subdivided further into endoparasitoids, which develop inside body of the host, and ectoparasitoids, which develop outside the host body, though the parasitoids frequently are attached or embedded in the host's tissues.

It is fairly common for a parasitoid itself to serve as the host for another parasitoid's offspring. The latter is commonly termed a hyperparasite
Hyperparasite
A hyperparasite is a parasite whose host is a parasite. This form of parasitism is especially common among entomophagous parasites....

, but in most cases this term is slightly misleading, as both the host and the primary parasitoid are killed. A better term might be secondary parasitoid, or hyperparasitoid.

Most known specialist hyperparasite and hyperparasitoid species are in the insect order Hymenoptera

Hymenoptera

, but a fair amount of incidental hyperparasitoidy results when a single host or a single food stash happens to house multiple guests and rations run short. Some members of the flesh fly family, Sarcophagidae, subfamily Miltogramminae

Miltogramminae

Miltogramminae is a subfamily of the family Sarcophagidae.-Genera:*Aenigmetopia*Alusomyia*Ambouya*Amobia*Apodacra*Beludzhia*Chaetapodacra*Chivamyia*Craticulina*Dolichotachina*Eremasiomyia...

, for example members of the genus Craticulina

Craticulina

Craticulina is a genus of true flies in the family Sarcophagidae. They are cleptoparasites of various species of sand wasps. They are ovoviviparous, laying larvae instead of eggs. The larvae share the prey of the sand wasp, and though they are much smaller than the wasps, there may be many fly...

, are kleptoparasites

Kleptoparasitism

Kleptoparasitism or cleptoparasitism is a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food...

of wasps in the subfamilies Bembicinae

Bembicinae

The Bembicinae is a large subfamily of crabronid wasps, that includes over 80 genera, and over 1800 species. Bembicines were originally a part of a single large family Sphecidae, then for many years were treated as a separate family, and recently have been placed back into a larger family, the...

and Philanthinae

Philanthinae

The subfamilly Philanthinae is one of the largest groups in the wasp family Crabronidae, even though it contains only 9 genera. Historically, this subfamily has frequently been accorded family status. The subfamily consists of solitary, predatory wasps, each genus having its own distinct and...

(both currently believed to be in the family Crabronidae

Crabronidae

Crabronidae is a large family of wasps, that includes nearly all of the species formerly comprising the now-defunct superfamily Sphecoidea. It collectively includes well over 200 genera, containing well over 9000 species. Crabronids were originally a part of Sphecidae, but the latter name is now...

). Both those subfamilies tend to build nests by digging tunnels in sand, which they then stock piecemeal with prey such as flies or bees, depending on the species. Kleptoparasitic flies such as Craticulina are much smaller than the host wasp and lay their eggs on the prey as the wasp returns to the nest on a victualing flight. The fly larvae are small, though faster-growing than the wasp larva, and if there is only one, the wasp is likely to complete its metamorphosis successfully, but when there are several it might suffer from malnutrition or even get eaten itself, which amounts to incidental kleptoparasitoidy.

In contrast though, as described in the following section, some insects, such as some members of the Trigonalidae

Trigonalidae

Trigonalidae is one of the more unusual families of hymenopteran insects, of indeterminate affinity within the suborder Apocrita , and presently placed in its own superfamily, Trigonaloidea...

, not only are specialist hyperparasitoids, but have advanced behavioural adaptations to support their speciality.

Note once again that there is no clear separation between the concepts of parasitism and parasitoidy. Many species of true parasites can cause the death of their host if for example they are present in overwhelming numbers or the host is in poor condition, or other compromising circumstances develop, such as secondary infections

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

. For example, blood-sucking mites sometimes overwhelm nestlings of birds such as swallows to the point that the young birds cannot fledge

Fledge

Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...

successfully,.

Infestations of other mites cause various kinds of mange

Mange

Mange is the common name for a class of persistent contagious skin diseases caused by parasitic mites. Since mites also infect plants, birds, and reptiles, the term "mange," suggesting poor condition of the hairy coat due to the infection, is sometimes reserved only for pathological...

in mammals. Mange mites are generally in the families Demodicidae that cause Demodicosis

Demodicosis

Demodicosis, also called demodectic mange or red mange, is caused by a sensitivity to and overpopulation of Demodex canis as the animal's immune system is unable to keep the mites under control....

or demodectic mange, Sarcoptidae

Sarcoptidae

Sarcoptidae is a family of mites, of which the most prominent are in the Genus Sarcoptes. Sarcoptic mange is caused by digging mites in that genus....

that cause scabies or sarcoptic mange, and Psoroptidae

Psoroptidae

Psoroptidae is a family of mites....

that cause scab in sheep and rabbits. Severe mange can debilitate animals to the point that they cannot feed themselves adequately, so that in unfavourable circumstances they may die.

Again, various species of paralytic ticks sometimes kill dogs if the owners are insufficiently alert, and soft ticks

Argasidae

Argasidae is a family of ticks containing the soft ticks. They lack the hard scutum that is present in the hard ticks . The capitulum is located on the underside of the animal's body and is not readily visible...

can fatally poison a host such as a horse that might rest in an infested shady spot because it does not know the local hazards.Holm, Erik, Dippenaar-Schoeman, Ansie; Goggo Guide; LAPA publishers (URL: WWW.LAPA.co.za). 2010 Conversely, some parasitoids do somewhat shorten the lives of their hosts or constrain their reproduction, but without necessarily killing them as a part of their interaction. Almost any microbial

Microorganism

A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...

disease could be defined as a parasitic condition, and some could be argued to amount to clear examples of parasitoidy. One converse argument is that when the death of the host is neither a logical nor necessarily even a desirable consequence from the point of view of the parasite, the relationship should be regarded as parasitic rather than parasitoidal. This certainly would apply to examples such as mange, and diseases in which the living victim acts as a natural reservoir

Natural reservoir

Natural reservoir or nidus, refers to the long-term host of the pathogen of an infectious disease. It is often the case that hosts do not get the disease carried by the pathogen or it is carried as a subclinical infection and so asymptomatic and non-lethal...

or even a vector.

In their extreme forms the categories of parasitism and parasitoidy patently are distinct; one is in no doubt whether the larva of a Tarantula hawk

Tarantula hawk

A tarantula hawk is a spider wasp which hunts tarantulas as food for its larvae. Tarantula hawks belong to any of the many species in the genera Pepsis and Hemipepsis in the family Pompilidae ....

wasp behaves more like a parasitoid, or even a predator, than a parasite; and similarly the biting midges

Ceratopogonidae

Ceratopogonidae, or biting midges , are a family of small flies in the order Diptera...

that suck blood from large insects plainly are simply ectoparasites

Parasitism

. However, there is a continuum of intermediate and contingent conditions that bridge those categories in practically every respect. This should not be taken too seriously as a material problem in terminology

Terminology

Terminology is the study of terms and their use. Terms are words and compound words that in specific contexts are given specific meanings, meanings that may deviate from the meaning the same words have in other contexts and in everyday language. The discipline Terminology studies among other...

; the terms are useful in particular contexts and should not be abused by inappropriate application in contexts in which they create confusion rather than clarity. Many examples of species that are technically parasitoidal, at least facultatively, are not generally referred to as parasitoidal. Many microbial diseases and the aforementioned soft ticks constitute instructive examples.

Nor do those complete the list of examples that constitute the requirement for fuzzy

Fuzzy logic

Fuzzy logic is a form of many-valued logic; it deals with reasoning that is approximate rather than fixed and exact. In contrast with traditional logic theory, where binary sets have two-valued logic: true or false, fuzzy logic variables may have a truth value that ranges in degree between 0 and 1...

distinctions in such matters; at the opposite extreme from parasitism, parasitoidy in turn grades into predation

Predation

In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...

. Differences between various kinds of hunting wasps provide convenient illustrations. Predatory social wasps hunt flies, caterpillars and the like, grab them, butcher them, carry them home and feed them to their young. That is patent predation. Some solitary wasps, such as bee pirates, sting prey, sometimes fatally, before saving it, usually entire, in a nest or burrow for the young to feed on. That too is predation, fairly clearly.

In contrast, the best-known protelean solitary hunting wasps sting prey to paralyse

Paralysis

Paralysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...

it before storing it for the young in the nest. The larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e then proceed to eat the stored prey alive, sometimes according to very sophisticated schedules that delay killing the victim sooner than necessary, thereby avoiding having their rations rot before they could be consumed. Some authorities regard such larval behaviour as having a strong element of parasitoidy. That view is based largely on the view that the young larvae begin with small exactions like any parasite, then proceed to the point where they eat at such a rate that they might as well be predators.

Other wasps paralyse prey in the plant or other environment in which it feeds, before laying eggs nearby. The emerging young attack and feed on the paralysed prey organism in its own home. Some solitary parasitoids among insects lay their eggs on or in their live prey and any of a wide range of consumption schedules might follow. Some parasitoids even lay their eggs where the larvae must locate the prey for themselves when they hatch from the eggs. Examples include flies in the families Tachinidae

Tachinidae

Tachinidae is a large and rather variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. There are over 1300 species in North America. Insects in this family are commonly called tachina flies or simply tachinids...

and Bombyliidae

Bombyliidae

Bombyliidae is a large family of flies with hundreds of genera, although their life cycles are not well known. Adults generally feed on nectar and pollen, thus are pollinators of flowers. They superficially resemble bees, thus are commonly called bee flies, and this may offer the adults some...

. The physiological and strategic

Evolutionarily stable strategy

sophistication of such relationships, whether parasitoidal or parasitic, often are impressive.

Patently there is no point to trying to draw arbitrary lines of distinction between such vague, and often variable, life histories. In each ecological

Ecology

Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

or ethological

Ethology

Ethology is the scientific study of animal behavior, and a sub-topic of zoology....

study the terms applied should reflect the facts in the contexts relevant to the matter in question. Such studies need not in all cases use the identical terminology, and there is no reason they should. All that is necessary is that the terminology in each study should be clear, useful and relevant.

Types of parasitoids

The parasitoidal type of relationship seems to occur largely in organisms that have fast reproduction rates, such as insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s or (perhaps more rarely) mite

Mite

Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...

s or nematodes. Workers in this field have pointed out that parasitoids often are closely coevolved with their hosts, which is inarguably true. To maintain a sound perspective of the matter though, one must remember that coevolution might reasonably be expected to develop to even higher degrees of sophistication in the more intimate classes of parasitic relationships. In fact advanced degrees of coevolution occur in the arms races of predator-prey relationships

Predation

as well.

In using the term parasitoid it is common to think in terms of parasitoidal insects such as Tachinidae

Tachinidae

and Pompilidae

Spider wasp

Wasps in the family Pompilidae are commonly called spider wasps . The family is cosmopolitan, with some 5,000 species in 6 subfamilies...

. Some writers recognise or discuss no other classes of parasitoidy. More realistically however, the life histories of several other groups of organisms are equally parasitoidal. In general there is no logical basis for excluding wider use of the term. For example, among the so-called worms, many Nematoda are important parasitoids of insects, snails and similar commercially important pest organisms. Under favourable circumstances they commonly multiply in the host until the carcase is a shell overflowing with a pullulating mass of worms.

Other organisms that might merit the term include certain Pteromalid

Pteromalidae

Pteromalidae is a very large family of parasitic wasps, with some 3,450 described species in some 640 genera...

gall wasps that abort host plant inflorescences, seed weevils, certain plants largely regarded as parasitic, and certain bacteria and viruses (e.g., bacteriophage

Bacteriophage

A bacteriophage is any one of a number of viruses that infect bacteria. They do this by injecting genetic material, which they carry enclosed in an outer protein capsid...

s), in relationships where the beneficiaries obligately destroy their hosts.

Not all such organisms regularly behave quite so parasitoidally of course; for example some bacteriophages establish complex life cycles in which phage particles do get released catastrophically, but only at intervals of many generations of the host, whereas other bacterial viruses emerge intermittently but fairly harmlessly in small numbers at a time.

The clearest cases of fully functional parasitoidy are the likes of many parasitoidal wasps and flies that consume their hosts as completely as any spider or hawk that summarily eats its prey. However, there also are many species of parasitoid that frequently or even routinely kill their "host" or "prey"

Predation

without consuming much of it. This apparently wasteful strategy sometimes might have the effect of reducing the risk that the prey could escape or offer resistance. In other cases the residue of the victim simply might be difficult to eat or not very nutritious. For example various Phorid flies such as Apocephalus

Paraponera

Paraponera is a genus of ant consisting of a single species, commonly known as the lesser giant hunting ant, conga ant, or bullet ant , named on account of its powerful and potent sting, which is said to be as painful as being shot with a bullet. It inhabits humid lowland rainforests from Nicaragua...

species, are parasitoids of particular species of ants. Various species attack ant genera such as "big-headed ants"

Pheidole

Pheidole is a genus of ant that belongs to the ant subfamily Myrmicinae.-The Genus:The genus Pheidole is widespread and ecologically dominant...

, "Fire ants"

Fire ant

Fire ants are a variety of stinging ants with over 285 species worldwide. They have several common names, including ginger ants, tropical fire ants and red ants.- Appearance :...

or Solenopsis, Paraponera

Paraponera

, and leaf-cutter ants. However, the larvae of most such Phoridae eat mainly the contents of the ants' "head capsules" abandoning the rest of the carcases when pupating. In laying her eggs, the parent fly selects the largest ant workers, which have just the size of head to produce an adequate adult phorid. Presumably the large head-capsule contains the most concentrated nutritious muscle and brain tissue. One also could think of the Rabies virus

Rabies virus

The rabies virus is neurotropic virus that causes fatal disease in human and animals. Rabies transmission can occur through the saliva of animals....

in similar terms, or the aforementioned soft ticks. Both commonly or invariably cause the death of the host, after consuming at most a trivial fraction of the host's resources.

Influence on host behaviour

In another strategy, some parasitoids influence the host's behaviour in ways that favour the propagation of the parasitoid, often at the cost of the host's own life. A spectular example is the endoparasitoid Dicrocoelium dendriticum

Dicrocoelium dendriticum

The Lancet liver fluke is a parasite fluke that tends to live in cattle or other grazing mammals.- History of discovery :...

, the Lancet Liver Fluke

Dicrocoelium dendriticum

The Lancet liver fluke is a parasite fluke that tends to live in cattle or other grazing mammals.- History of discovery :...

that causes host ants to die clinging to grass stalks where grazers or birds may be expected to eat them and complete the parasitoidal fluke's life cycle in its definitive host

Host (biology)

. Similarly, as strepsiptera

Strepsiptera

The Strepsiptera are an order of insects with ten families making up about 600 species...

n parasitoids of ants mature, they cause the hosts to dawdle high on grass stalks, positions that are risky, but favour the emergence of the Strepsipterans. Other species of endoparasitoids cause infected woodlice

Woodlouse

A woodlouse is a crustacean with a rigid, segmented, long exoskeleton and fourteen jointed limbs...

and land Amphipoda

Amphipoda

Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. The name amphipoda means "different-footed", and refers to the different forms of appendages, unlike isopods, where all the legs are alike. Of the 7,000 species, 5,500 are classified...

such as Talitroides

Talitridae

Talitridae is a family of amphipods. Commonly, many of the North American fresh water species of this family are called scuds. Terrestrial species are often referred to as landhoppers and beach dwellers are called sandhoppers or sand fleas.It contains the following genera:*Africorchestia Lowry &...

to run about in the open by day, where predators such as birds can catch them and continue the cycle.

Returning to the case of the rabies virus

Rabies virus

The rabies virus is neurotropic virus that causes fatal disease in human and animals. Rabies transmission can occur through the saliva of animals....

and the disease

Rabies

Rabies is a viral disease that causes acute encephalitis in warm-blooded animals. It is zoonotic , most commonly by a bite from an infected animal. For a human, rabies is almost invariably fatal if post-exposure prophylaxis is not administered prior to the onset of severe symptoms...

, one could rationalise the death of the host similarly. The virus affects the host's central nervous system

Central nervous system

The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

with eventually fatal effects. That could be seen as a consequence of the strategy for dissemination of the virus by affecting the host behaviour. Similar principles might apply to, for example, Vibrio cholerae
Vibrio cholerae
Vibrio cholerae is a Gram-negative, comma-shaped bacterium. Some strains of V. cholerae cause the disease cholera. V. cholerae is facultatively anaerobic and has a flagella at one cell pole. V...

, the cholera

Cholera

Cholera is an infection of the small intestine that is caused by the bacterium Vibrio cholerae. The main symptoms are profuse watery diarrhea and vomiting. Transmission occurs primarily by drinking or eating water or food that has been contaminated by the diarrhea of an infected person or the feces...

bacterium

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

and other, often fatal, enteric

Enteric

Enteric can refer to:* A general term describing something related to or associated with the intestines** Microorganisms that inhabit the intestines are commonly known as enteric bacteria* Enteric nervous system...

pathogen

Pathogen

A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...

s that induce diarrhoea

Diarrhea

Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...

and spread by contagion.

For the soft ticks the benefit of the paralysis they inflict might be seen as influencing behaviour in that it prevents the host from wandering away while they feed, which they do very quickly and in large numbers, some species emerging from their hiding places at night. Other species hide in sandy patches in the shade of trees in semi-desert such as the Kalahari

Kalahari Desert

The Kalahari Desert is a large semi-arid sandy savannah in Southern Africa extending , covering much of Botswana and parts of Namibia and South Africa, as semi-desert, with huge tracts of excellent grazing after good rains. The Kalahari supports more animals and plants than a true desert...

, and emerge to feed as soon as any large animal settles down in the shade during the heat of the day.

In parasitic birds such as cuckoo

Cuckoo

The cuckoos are a family, Cuculidae, of near passerine birds. The order Cuculiformes, in addition to the cuckoos, also includes the turacos . Some zoologists and taxonomists have also included the unique Hoatzin in the Cuculiformes, but its taxonomy remains in dispute...

s, the young often are adapted to act as "super solicitors", with loud, persistent voices and with large, vividly coloured gapes and behaviour that stimulate the feeding instincts of the foster parents to the utmost. Consequently the legitimate chicks, even if they are not evicted, often starve because they are less well-equipped for soliciting for food.

Parasitoidal microbial diseases

As mentioned, some microbial parasitoids waste most of the host's resources when it dies, but there are other parasitoidal strategies among microbes as well. One more conceptually economical form of parasitoidy is exemplified by microbial pathogens of various invertebrates such as many insects. The most notorious might well be Microsporidiosis

Microsporidiosis

Microspridiosis is an opportunistic intestinal infection that causes diarrhea and wasting in immunocompromised individuals . It results from different species of microsporidia, a group of microbial fungi....

in the form of nosema

Pébrine

Pébrine is a disease of silkworms, which is caused by microsporidian parasites, mainly Nosema bombycis and to a lesser extent Variomorpha, Pleistophora and Thelophania species....

in silkworms

Bombyx mori

The silkworm is the larva or caterpillar of the domesticated silkmoth, Bombyx mori . It is an economically important insect, being a primary producer of silk...

. This infection is highly virulent

Virulence

Virulence is by MeSH definition the degree of pathogenicity within a group or species of parasites as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenicity of an organism - its ability to cause disease - is determined by its...

and the tissues of the victims contain huge numbers of infectious

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

spore

Spore

In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

s. In effect the pathogen

Pathogen

in its role of parasitoid has used up most of the resources of the host to propagate and spread its offspring. Similarly, many viruses, bacterial and other, continue to propagate inside a host cell until it physically ruptures. In doing so they too consume effectively the whole of the host's resources.

Parasitoidal fungi such as Entomophthora

Entomophthorales

The Entomophthorales are an order of fungi that were previously classified in the class Zygomycetes. A new subphylum, Entomophthoromycotina, has recently been described for them.Most species of the Entomophthorales are pathogens of insects...

species carry this principle as far as is possible. Having infected and killed an insect, they continue to grow on the carcase and release spores for as long as any resources remain. In this such microbes resemble the aforementioned propagation of some Nematoda in snails and insects.

Parasitoidal plants

There are parasitoidal plants as well. Various species of dodder

Cuscuta

Cuscuta is a genus of about 100-170 species of yellow, orange or red parasitic plants. Formerly treated as the only genus in the family Cuscutaceae, recent genetic research by the Angiosperm Phylogeny Group has shown that it is correctly placed in the morning glory family, Convolvulaceae...

indiscriminately parasitise wide ranges of host plants, and debilitate or kill the branches that they infect, and commonly the whole host plant as well.

Mistletoe

Mistletoe

Mistletoe is the common name for obligate hemi-parasitic plants in several families in the order Santalales. The plants in question grow attached to and within the branches of a tree or shrub.-Mistletoe in the genus Viscum:...

s in families such as Santalaceae

Santalaceae

Santalaceae is a widely distributed family of flowering plants which, like other members of Santalales, are partially parasitic on other plants...

and Loranthaceae

Loranthaceae

Loranthaceae is a family of flowering plants, which has been universally recognized by taxonomists. It consists of about 75 genera and 1,000 species of woody plants, many of them hemi-parasites, all of them except three having the mistletoe habit...

commonly accumulate on host trees till they stunt and eventually kill them, sometimes after many decades. Occasionally a freak condition can arise where the (strictly speaking "hemiparasitic"

Parasitic plant

A parasitic plant is one that derives some or all of its sustenance from another plant. About 4,100 species in approximately 19 families of flowering plants are known. Parasitic plants have a modified root, the haustorium, that penetrates the host plant and connects to the xylem, phloem, or...

) plant can supply sufficient photosynthetic power to support the root system of a small host tree for several years after the live host shoots have effectively disappeared.

A related example is where the parasitoid plant is not strictly a parasite in the normal sense, but none the less exploits the host's resources of space, support and light. The best-known are the so-called "strangler figs"

Strangler Fig

Strangler fig is the common name for a number of tropical and subtropical plant species, including some banyans and unrelated vines, including among many other species:* Ficus aurea, also known as the Florida Strangler Fig...

. Some of them will grow on and round the trunk of the host tree and squeeze it or starve it of light until, after perhaps decades, it dies. The strangler eventually replaces the host utterly as the original trunk rots from within the stems of the strangler, leaving a hollow framework.

Parasitoidal crustaceans

The subphylum

Subphylum

In life, a subphylum is a taxonomic rank intermediate between phylum and superclass. The rank of subdivision in plants and fungi is equivalent to subphylum.Not all phyla are divided into subphyla...

Crustacea

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

includes a surprising range of parasitoidal species and strategies. As with many other parasitoids, the killing of the host often is incidental. For example, in the family

Taxonomic rank

In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...

Ergasilidae

Ergasilidae is a widespread family of copepods and comprises many species. The type genus is Ergasilus. With a few doubtful exceptions all ergasilids are parasitic on fishes.-Biology:...

, the "gill lice", most adult females live as parasites in the gills of fish. The harm they do the host is incidental to the parasitism, but it often is fatal or at least debilitates the fish so badly as to prevent breeding.

A particularly startling genus of Cirripedia, or barnacles is Sacculina

Sacculina

Sacculina is a genus of barnacles that is a parasitic castrator of crabs. The adults bear no resemblance to the barnacles that cover ships and piers; they are recognised as barnacles because their larval forms are like other members of the barnacle class Cirripedia...

. It literally injects itself into a crab of a suitable species and by complex processes converts itself into an egg-laying bag. In the process it disrupts the reproductive system of the host, an act of parasitic castration

Parasitic castration

that qualifies it for classification as a parasitoid rather than just a parasite.

Those examples are just a few of many among the Crustacea.

Parasitoidal insects

About 10% of described insect species are entomophagous parasitoids

Entomophagous parasite

Entomophagous parasites are insects that are parasitic on other insects. Nearly all insects are attacked by one or more insect parasites. This parasitic mode of life is most often confined to the larvae with the adults usually leading free lives...

. There are four insect orders that are particularly renowned for this type of life history. By far the majority are in the order Hymenoptera

Hymenoptera

.

The largest and best-known group comprises the so-called "Parasitica" within the Hymenopteran suborder Apocrita

Apocrita

Apocrita is a suborder of insects in the order Hymenoptera.Apocrita includes wasps, bees and ants, and consists of many families. It includes the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" formed between the first two segments of the actual abdomen; the...

: the largest subgroups of these are the chalcidoid wasps (superfamily

Taxonomic rank

Chalcidoidea) and the ichneumon wasps (superfamily Ichneumonoidea), followed by the Proctotrupoidea

Proctotrupoidea

The Hymenopteran superfamily Proctotrupoidea is a somewhat confusing assemblage of taxa, with new families being added with surprising frequency, and very little to unify them all into a single natural group...

and Platygastroidea

Platygastroidea

The Hymenopteran superfamily Platygastroidea has, in the past, often been treated as a lineage within the superfamily Proctotrupoidea, but most classifications since 1977 have recognized it as an independent group, composed of two families, the Platygastridae and the Scelionidae, with a combined...

. Outside of the Parasitica, many other Hymenopteran lineages that include parasitoids, such as most of the Chrysidoidea

Chrysidoidea

The superfamily Chrysidoidea is a very large cosmopolitan group of parasitoid or cleptoparasitic wasps, with three large, common families and four tiny, rare families. Most species are small , almost never exceeding 15 mm...

and Vespoidea

Vespoidea

Vespoidea is a superfamily of order Hymenoptera of class Insecta, although older taxonomic schemes may vary in this categorization, particularly in their recognition of a now-obsolete superfamily Scolioidea...

, and the rare Symphytan family Orussidae

Orussidae

The family Orussidae is the only Symphytan group which is parasitic, thus giving them the common name parasitic wood wasps...

.

The flies (order Diptera

Diptera

) include several families of parasitoids, the largest of which is the family

Taxonomic rank

Tachinidae

, and also smaller families such as Pipunculidae

Pipunculidae

Pipunculidae are a family of flies , commonly termed Big-Headed Flies a reference to the large eyes , which cover nearly the entire head...

, Conopidae

Conopidae

Conopidae, usually known as the thick-headed flies, is a family of flies within the Brachycera suborder of Diptera. Flies of the family Conopidae are distributed worldwide except for the poles and many of the Pacific islands. About 800 species in 47 genera are described worldwide, approximately 70...

, and others. Other families of flies that are not primarily parasitoids or parasites, or at least not primarily protelean, do nonetheless include protelean species. For example Phoridae have already been mentioned as parasitoidal on ants, and at least some flesh fly species, such as Emblemasoma auditrix, are parasitoidal on cicadas, and have raised great interest because they locate their hosts by sound. The kleptoparasitic flesh fly genus Craticulina has already been mentioned and logically qualifies as a protelean fly genus.

Two other orders with parasitoidal members are the "twisted-wing parasites" (order Strepsiptera

Strepsiptera

The Strepsiptera are an order of insects with ten families making up about 600 species...

), which is a small group consisting entirely of parasitoids, and the beetles (order Coleoptera), which includes at least two families, Ripiphoridae

Ripiphoridae

The family Ripiphoridae is a cosmopolitan group of beetles commonly known as wedge-shaped beetles containing some 450 species...

and Rhipiceridae, that are largely parasitoids, and rove beetle

Rove beetle

The rove beetles are a large family of beetles, primarily distinguished by their short elytra that leave more than half of their abdomens exposed. With over 46,000 species in thousands of genera, the group is the second largest family of beetles after the Curculionidae...

s (family Staphylinidae) of the genus Aleochara
Aleochara
Rove beetles of the genus Aleochara are among the only insect parasites in the beetle family Staphylinidae. Most of the Aleochara are more rightly called parasitoids because their larvae use a single host, which is killed during the beetle's maturation. Adult Aleochara are predators...

. Occasional members of other orders can be parasitoids; one of the more remarkable is the moth

Moth

A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

family Epipyropidae

Epipyropidae

Epipyropidae is a small family of moths. This family and the closely related Cyclotornidae are unique among the Lepidoptera in that the larvae are ectoparasites, the hosts typically being fulgoroid planthoppers, thus the common name Planthopper Parasite Moths.-References:*...

, which are ectoparasitoids of planthopper

Planthopper

A planthopper is any insect in the infraorder Fulgoromorpha within the Hemiptera. The name comes from their remarkable resemblance to leaves and other plants of their environment and from the fact that they often "hop" for quick transportation in a similar way to that of grasshoppers. However,...

s and Cicada

Cicada

A cicada is an insect of the order Hemiptera, suborder Auchenorrhyncha , in the superfamily Cicadoidea, with large eyes wide apart on the head and usually transparent, well-veined wings. There are about 2,500 species of cicada around the world, and many of them remain unclassified...

s. The genus Cyclotorna has even more elaborate habits, beginning its growth period parasitising plant bugs, and concluding by feeding on ant larvae in their colonies.

Hymenopteran parasitoids often have unique life cycles. In one family, the Trigonalidae

Trigonalidae

Trigonalidae is one of the more unusual families of hymenopteran insects, of indeterminate affinity within the suborder Apocrita , and presently placed in its own superfamily, Trigonaloidea...

, the female wasps deposit eggs into small pockets they cut into the edge of leaves with their ovipositor

Ovipositor

The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...

. A caterpillar chewing these leaves may unknowingly swallow some of the eggs, and when they get into the caterpillar's gut, they hatch and burrow through the gut wall and into the body cavity. Later they search the caterpillar's body cavity for other parasitoid larvae, and it is these they attack and feed on. Some trigonalids, once in a caterpillar or sawfly larva, need their vehicle to fall prey to a social wasp. The wasp carries the caterpillar back to its nest, and there it is butchered and fed to the wasp's young; they will serve as the host for the trigonalid, the eggs of which are in the butchered caterpillar.

Parasitoidal and Parasitic Vertebrates

Perhaps because they are less specialised and their relationships with their hosts are less intimate than is the case with many invertebrates, it often is more difficult to distinguish parasitism from parasitoidy in vertebrates. In fact many of their relationships of such types do not immediately suggest parasitism to most people at all. However, the very concept is so open to interpretation that it emerges frequently in vertebrate biology.

Kleptoparasitism

Kleptoparasitism

for example is ubiquitous, and is a major constraint on reproduction or even survival among vertebrate predators, especially in times of famine

Famine

A famine is a widespread scarcity of food, caused by several factors including crop failure, overpopulation, or government policies. This phenomenon is usually accompanied or followed by regional malnutrition, starvation, epidemic, and increased mortality. Every continent in the world has...

. Male lions in a pride for example, largely leave hunting for non-threatening prey to females. However, prides that specialise in very large prey such as giraffes, elephants,http://www.timesonline.co.uk/tol/life_and_style/article658614.ece or buffalo, may behave differently.

Other predators such as cheetah, leopard, and even lions sometimes may be chased from their kills by hyaenas. Hyaena

Hyena

Hyenas or Hyaenas are the animals of the family Hyaenidae of suborder feliforms of the Carnivora. It is the fourth smallest biological family in the Carnivora , and one of the smallest in the mammalia...

may sometimes follow such predators so routinely in the hope of confiscating their kills, that the hunters spend more effort on avoiding hyaena than on hunting.

Ethologists

Ethology

Ethology is the scientific study of animal behavior, and a sub-topic of zoology....

could multiply examples of kleptoparasitism many-fold; it may be intraspecific

Intraspecific

Intraspecific is a term used in biology to describe behaviors, biochemical variations and other issues within individuals of a single species, thereby contrasting with interspecific. For example:* Intraspecific antagonism...

or interspecific

Interspecific

Interspecific is a term used in biology to describe behaviors, biochemical variations and other issues between individuals of separate species, thereby contrasting with intraspecific...

; it ranges from the smallest foragers

Foraging

- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...

and predators to the largest, and may combine with predation, where the robber is happy to eat both hunter and prey. Curiously though, interspecific robbers often show at least some constraint as though they were robbing conspecifics, and do not necessarily attack the host as directly as they would have done had there not been a "robbery" situation. Interpretation and speculation about the nature of such behaviour is beyond the scope of this article however.

It is not easy to classify such relationships, because many of them involve degrees of payment in terms of protection and other benefits; for example the male lions who preempt the females' kills do at least offer protection from hyaenas and rival males.

Kleptoparasitism occurs in many other forms among vertebrates (see here for example

Kleptoparasitism

), but for it to lead to the death of the host is not so common, and this would seem to disqualify it from the category of parasitoidy. Still, when the hosts are hard pressed in hard circumstances, the resulting injury and famine could cause reduced reproduction and even death.

Lamprey

Lamprey

Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...

s present both parasitic and parasitoidal examples. Most species are not parasitic, but among the North American species for example, there are several species ectoparasitic on freshwater fishes. They rasp away the skin of the host and suck the blood, but most do only superficial damage. In contrast the most notorious species is the sea lamprey

Sea lamprey

The sea lamprey is a parasitic lamprey found on the Atlantic coasts of Europe and North America, in the western Mediterranean Sea, and in the Great Lakes. It is brown, gray, or black on its back and white or gray on the underside and can grow up to 90 cm long. Sea lampreys prey on a wide...

, Petromyzon marinus. Its rasping wounds can extend deep into the host's flesh, and the muscle damage and loss of blood commonly weaken the host severely, affecting its reproduction unfavourably. Often the harm is severe enough to kill the host, which is about as clear an example of parasitoidy as one could ask.

Hagfish

Hagfish

Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates...

, are distant relatives of lampreys. They are largely carrion feeders and predators of large worms and similar small creatures, but various species also attack weakened fishes much as some lampreys do, and accordingly rank as opportunistic parasitoids under at least some conditions.

The sabre-toothed blenny

Sabre-toothed blenny

The sabre-toothed blenny, Aspidontus taeniatus, is a species of blenny that mimics the "dance" of Labroides dimidiatus; a similarly colored species of cleaner wrasse. It tricks fish into offering their underparts to be cleaned. Instead of eating parasites from the scales of the fish, the...

presents a curiously difficult example of parasitism to classify. It parasitises the relationship between some cleaner fish

Cleaner fish

Cleaner fish are fish that provide a service to other fish species by removing dead skin and ectoparasites. This is an example of mutualism, an ecological interaction that benefits both parties involved. A wide variety of fishes have been observed to display cleaning behaviors including wrasses,...

and their client fishes, more than it parasitises either party to the relationship; it attacks the client fish, approaching it in the guise of cleaner wrasse and snatches a mouthful of scales or other convenient tissue. Clients often react violently, and thereafter trust neither wrasse nor the wrasse-mimicking blenny. In its violence and the pernicious effect on a valuable relationship, it suggests parasitoidy as well as parasitism.

Another form of parasitism that can approach parasitoidy occurs in the Perissodini

Perissodini

Perissodini is a tribe of African cichlids, containing nine species of freshwater fish.Two of the species feed on small fish and zooplankton.Seven species are specialised in eating scales from other fish.-External links:...

, Cichlids from Lake Tanganyika

Lake Tanganyika

Lake Tanganyika is an African Great Lake. It is estimated to be the second largest freshwater lake in the world by volume, and the second deepest, after Lake Baikal in Siberia; it is also the world's longest freshwater lake...

. Seven species in the genus Perissodus are specialised in eating scales from other fish. Their teeth are variously suited to being able to grab bits of skin with the scales attached, and such bits of skin and scale formed major components of the stomach contents. At least some of the species also have adaptations in their behavior to enable them to approach potential hosts They also have an adaptation of the jaw that enables them to lash out sideways in passing a victim; the jaw is asymmetrical, and there is continuous selection for the asymmetry that currently is less frequent in the population, because host fishes are more alert to defend themselves on the side on which they have been attacked in the past.

Such a lifestyle is reminiscent of sharks of the genus Isistius

Isistius

Isistius is a genus of dogfish sharks in the family Dalatiidae. They are commonly known as cookiecutter sharks. Members of the genus are known for their unusual behaviour and dentition.-Species:...

, which is known as the Cookiecutter shark

Cookiecutter shark

The cookiecutter shark , also called the cigar shark, is a species of small dogfish shark in the family Dalatiidae. This shark occurs in warm, oceanic waters worldwide, particularly near islands, and has been recorded from as deep as . It migrates vertically up to every day, approaching the...

because of the circular wounds it leaves in the skins of whales and large fish that it has bitten in passing. Isistius species have been referred to as partly ectoparasitic, but they sometimes overwhelm their hosts and kill them, which by definition amounts to parasitoidy.

Candiru

Candirú

‎Candiru or candirú , also known as cañero, toothpick fish, or vampire fish, are a number of genera of parasitic freshwater catfish in the family Trichomycteridae; all are native to the Amazon River...

and related fishes in the Family

Family

In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...

Trichomycteridae

Trichomycteridae is a family of catfishes commonly known as the pencil or parasitic catfishes. This family includes the infamous candiru fish, feared by some people for its alleged habit of entering into the urethra of humans....

, subfamilies Vandelliinae

Vandelliinae

The Vandelliinae are a subfamily of catfishes of the family Trichomycteridae. Vandelliines are hematophagous, feeding on the blood of larger fish...

and Stegophilinae

Stegophilinae

Stegophilinae is a subfamily of catfishes of the family Trichomycteridae.It includes twelve genera, Acanthopoma, Apomatoceros, Haemomaster, Henonemus, Homodiaetus, Megalocentor, Ochmacanthus, Parastegophilus, Pareiodon, Pseudostegophilus, Schultzichthys, and Stegophilus...

, present unusual examples of vertebrate parasitism, and occasionally parasitoidy. Most popular accounts are obsessed with the idea of candiru entering the human urethra and other orifices, but they are very varied in their habits. Some burrow partway into the skin of larger fish, apparently largely for purposes of protection and transport rather than food. Several at least are haematophagous

Hematophagy

Hematophagy is the practice of certain animals of feeding on blood...

, commonly entering the gill cavities of larger fishes and feeding on blood drawn from the gill filaments. At least when large fishes are tethered by fishermen where large numbers of the parasites occur, the hosts may die. Possibly this effect is analogous to the effect of soft ticks on hosts that do not avoid the sand patches where they assemble.

Among birds the best-known forms of parasitism are brood parasitism by various species of cuckoo

Cuckoo

s, honey-guides, cowbirds, and several more. They qualify as parasitoids because many of them will cause the starvation of the host's chicks by competing with them for food, and many others either will remove host eggs when laying eggs in host nests, (sometimes eating the eggs removed), or the chick will eject or kill the eggs or chicks of the host when they hatch. Some hatchlings actually have hooked beaks adapted to attacking the host chicks and eggs, hooks that vanish before fledging.

External links

On the UF
University of Florida
The University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...

/ IFAS
Institute of Food and Agricultural Sciences
The University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...

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  Eulophidae
  Eulophidae is a large family of hymenopteran insects, with over 4,300 described species in some 300 genera . The family as presently defined also includes the genus Elasmus, which was previously treated as a separate family, "Elasmidae", and is now treated as a subfamily of Eulophidae...
  
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  Aphelinidae
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Parasitic and Parasitoid Alien Species in Science Fiction Movies

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