parasitic wasp
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Parasitoid wasps are a large group of
hymenoptera Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typic ...
n superfamilies, with all but the wood wasps (
Orussoidea Orussoidea is a superfamily of sawflies. It contains the living family Orussidae, as well as the extinct families Burmorussidae and Paroryssidae. They are the group of sawflies closest to the Apocrita, the group containing wasps, bees and ants ...
) being in the wasp-waisted Apocrita. As
parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...
s, they lay their eggs on or in the bodies of other
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s, sooner or later causing the death of these
hosts A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host ...
. Different species specialise in hosts from different insect orders, most often
Lepidoptera Lepidoptera ( ) is an order of insects that includes butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 percent of the total described speci ...
, though some select
beetles Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describe ...
, flies, or bugs; the spider wasps ( Pompilidae) exclusively attack
spider Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s. Parasitoid wasp species differ in which host life-stage they attack: eggs, larvae, pupae, or adults. They mainly follow one of two major strategies within
parasitism Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
: either they are endoparasitic, developing inside the host, and koinobiont, allowing the host to continue to feed, develop, and moult; or they are ectoparasitic, developing outside the host, and idiobiont, paralysing the host immediately. Some endoparasitic wasps of the superfamily Ichneumonoidea have a mutualistic relationship with
polydnavirus A polydnavirus (PDV) is a member of the family ''Polydnaviridae'' of insect viruses. There are two genera in the family: '' Bracovirus'' and '' Ichnovirus''. Polydnaviruses form a symbiotic relationship with parasitoid wasps; ( ichnoviruses ( ...
es, the viruses suppressing the host's immune defenses. Parasitoidism evolved only once in the Hymenoptera, during the
Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...
, leading to a single
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...
, but the parasitic lifestyle has secondarily been lost several times including among the ants,
bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfami ...
s, and yellowjacket wasps. As a result, the order Hymenoptera contains many families of parasitoids, intermixed with non-parasitoid groups. The parasitoid wasps include some very large groups, some estimates giving the
Chalcidoidea Chalcid wasps (, , for their metallic colour) are insects within the superfamily Chalcidoidea, part of the order Hymenoptera. The superfamily contains some 22,500 known species, and an estimated total diversity of more than 500,000 species, me ...
as many as 500,000 species, the
Ichneumonidae The Ichneumonidae, also known as the ichneumon wasps, Darwin wasps, or ichneumonids, are a family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 25,000 species cur ...
100,000 species, and the
Braconidae The Braconidae are a family of parasitoid wasps. After the closely related Ichneumonidae, braconids make up the second-largest family in the order Hymenoptera, with about 17,000 recognized species and many thousands more undescribed. One analysis ...
up to 50,000 species. Host insects have evolved a range of defences against parasitoid wasps, including hiding, wriggling, and camouflage markings. Many parasitoid wasps are considered beneficial to humans because they naturally control agricultural pests. Some are applied commercially in
biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also i ...
, starting in the 1920s with '' Encarsia formosa'' to control whitefly in
greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These ...
s. Historically, parasitoidism in wasps influenced the thinking of
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...
.


Parasitoidism

Parasitoid wasps range from some of the smallest species of insects to wasps about an inch long. Most females have a long, sharp ovipositor at the tip of the abdomen, sometimes lacking
venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a st ...
glands, and almost never modified into a
sting Sting may refer to: * Stinger or sting, a structure of an animal to inject venom, or the injury produced by a stinger * Irritating hairs or prickles of a stinging plant, or the plant itself Fictional characters and entities * Sting (Middle-earth ...
. Parasitoids can be classified in a variety of ways. They can live within their host's body as endoparasitoids, or feed on it from outside as ectoparasitoids: both strategies are found among the wasps. Parasitoids can also be divided according to their effect on their hosts. Idiobionts prevent further development of the host after initially immobilizing it, while koinobionts allow the host to continue its development while they are feeding upon it; and again, both types are seen in parasitoidal wasps. Most ectoparasitoid wasps are idiobiont, as the host could damage or dislodge the external parasitoid if allowed to move or
moult In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
. Most endoparasitoid wasps are koinobionts, giving them the advantage of a host that continues to grow larger and remains able to avoid predators.


Hosts

Many parasitoid wasps use larval Lepidoptera as hosts, but some groups parasitize different host life stages (egg, larva or nymph, pupa, adult) of nearly all other orders of insects, especially
Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describe ...
,
Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
,
Hemiptera Hemiptera (; ) is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from to arou ...
and other Hymenoptera. Some attack arthropods other than insects: for instance, the Pompilidae specialise in catching
spider Spiders (order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
s: these are quick and dangerous prey, often as large as the wasp itself, but the spider wasp is quicker, swiftly stinging her prey to immobilise it. Adult female wasps of most species oviposit into their hosts' bodies or eggs. Some also inject a mix of secretory products that paralyse the host or protect the egg from the host's immune system; these include
polydnavirus A polydnavirus (PDV) is a member of the family ''Polydnaviridae'' of insect viruses. There are two genera in the family: '' Bracovirus'' and '' Ichnovirus''. Polydnaviruses form a symbiotic relationship with parasitoid wasps; ( ichnoviruses ( ...
es, ovarian proteins, and venom. If a polydnavirus is included, it infects the nuclei of host hemocytes and other cells, causing symptoms that benefit the parasite. Host size is important for the development of the parasitoid, as the host is its entire food supply until it emerges as an adult; small hosts often produce smaller parasitoids. Some species preferentially lay female eggs in larger hosts and male eggs in smaller hosts, as the reproductive capabilities of males are limited less severely by smaller adult body size. Some parasitoid wasps mark the host with chemical signals to show that an egg has been laid there. This may both deter rivals from ovipositing, and signal to itself that no further egg is needed in that host, effectively reducing the chances that offspring will have to compete for food and increasing the offspring's survival.


Life cycle

On or inside the host the parasitoid egg hatches into a larva or two or more larvae (
polyembryony Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg. Due to the embryos resulting from the same egg, the embryos are identical to one another, but are genetically diverse from the parents. The genetic differ ...
). Endoparasitoid eggs can absorb fluids from the host body and grow several times in size from when they were first laid before hatching. The first
instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ...
larvae is often highly mobile and may have strong mandibles or other structures to compete with other parasitoid larvae. The following instars are generally more grub-like. Parasitoid larvae have incomplete digestive systems with no rear opening. This prevents the hosts from being contaminated by their wastes. The larva feeds on the host's tissues until ready to pupate; by then the host is generally either dead or almost so. A
meconium Meconium is the earliest stool of a mammalian infant resulting from defecation. Unlike later feces, meconium is composed of materials ingested during the time the infant spends in the uterus: intestinal epithelial cells, lanugo, mucus, amnioti ...
, or the accumulated wastes from the larva is cast out as the larva transitions to a prepupa. Depending on its species, the parasitoid then may eat its way out of the host or remain in the more or less empty skin. In either case it then generally spins a cocoon and pupates. As adults, parasitoid wasps feed primarily on nectar from flowers. Females of some species will also drink
hemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...
from hosts to gain additional nutrients for egg production.


Mutualism with polydnavirus

Polydnavirus A polydnavirus (PDV) is a member of the family ''Polydnaviridae'' of insect viruses. There are two genera in the family: '' Bracovirus'' and '' Ichnovirus''. Polydnaviruses form a symbiotic relationship with parasitoid wasps; ( ichnoviruses ( ...
es are a unique group of insect viruses that have a mutualistic relationship with some parasitic wasps. The polydnavirus replicates in the oviducts of an adult female parasitoid wasp. The wasp benefits from this relationship because the virus provides protection for the parasitic larvae inside the host, (i) by weakening the host's immune system and (ii) by altering the host's cells to be more beneficial to the parasite. The relationship between these viruses and the wasp is obligatory in the sense that all individuals are infected with the viruses; the virus has been incorporated in the wasp's genome and is inherited.


Host defenses

The hosts of parasitoids have developed several levels of defence. Many hosts try to hide from the parasitoids in inaccessible habitats. They may also get rid of their frass (body wastes) and avoid plants that they have chewed on as both can signal their presence to parasitoids hunting for hosts. The egg shells and cuticles of the potential hosts are thickened to prevent the parasitoid from penetrating them. Hosts may use behavioral evasion when they encounter an egg laying female parasitoid, like dropping off the plant they are on, twisting and thrashing so as to dislodge or kill the female and even regurgitating onto the wasp to entangle it. The wriggling can sometimes help by causing the wasp to "miss" laying the egg on the host and instead place it nearby. Wriggling of pupae can cause the wasp to lose its grip on the smooth hard pupa or get trapped in the silk strands. Some caterpillars even bite the female wasps that approach them. Some insects secrete poisonous compounds that kill or drive away the parasitoid. Ants that are in a symbiotic relationship with caterpillars, aphids or scale insects may protect them from attack by wasps. Even parasitoid wasps are vulnerable to hyperparasitoid wasps. Some parasitoid wasps change the behavior of the infected host, causing them to build a silk web around the pupae of the wasps after they emerge from its body to protect them from hyperparasitoids. Hosts can kill endoparasitoids by adhering hemocytes to the egg or larva in a process called encapsulation. In
aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...
s, the presence of a particular species of γ-3
Pseudomonadota Pseudomonadota (synonym Proteobacteria) is a major phylum of Gram-negative bacteria. The renaming of phyla in 2021 remains controversial among microbiologists, many of whom continue to use the earlier names of long standing in the literature. Th ...
makes the aphid relatively immune to their parasitoid wasps by killing many of the eggs. As the parasitoid's survival depends on its ability to evade the host's immune response, some parasitoid wasps have developed the counterstrategy of laying more eggs in aphids that have the endosymbiont, so that at least one of them may hatch and parasitize the aphid. Certain caterpillars eat plants that are toxic to both themselves and the parasite to cure themselves. ''
Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the " vinegar fly" or "pomace fly". Starting with ...
'' larvae also self-medicate with ethanol to treat parasitism. ''D. melanogaster'' females lay their eggs in food containing toxic amounts of alcohol if they detect parasitoid wasps nearby. The alcohol protects them from the wasps, at the cost of retarding their own growth.


Evolution and taxonomy


Evolution

Based on genetic and fossil analysis, parasitoidism has evolved only once in the Hymenoptera, during the
Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...
, leading to a single
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...
, the Apocrita. All parasitoid wasps are descended from this lineage, except for the
Orussoidea Orussoidea is a superfamily of sawflies. It contains the living family Orussidae, as well as the extinct families Burmorussidae and Paroryssidae. They are the group of sawflies closest to the Apocrita, the group containing wasps, bees and ants ...
which are parasitic but lack the wasp waist. The Apocrita emerged during the
Jurassic The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
. The
Aculeata Aculeata is a subclade of Hymenoptera containing ants, bees, and stinging wasps. The name is a reference to the defining feature of the group, which is the modification of the ovipositor into a stinger. However, many members of the group cannot ...
, which includes bees, ants, and parasitoid spider wasps, evolved from within the Apocrita; it contains many families of parasitoids, though not the Ichneumonoidea,
Cynipoidea The Cynipoidea are a moderate-sized hymenopteran superfamily that presently includes five modern families and three extinct families, though others have been recognized in the past. The most familiar members of the group are phytophagous, especia ...
, and
Chalcidoidea Chalcid wasps (, , for their metallic colour) are insects within the superfamily Chalcidoidea, part of the order Hymenoptera. The superfamily contains some 22,500 known species, and an estimated total diversity of more than 500,000 species, me ...
. The Hymenoptera, Apocrita, and Aculeata are all clades, but since each of these contains non-parasitic species, the parasitoid wasps, formerly known as the Parasitica, do not form a clade on their own. The common ancestor in which parasitoidism evolved lived approximately 247 million years ago and was previously believed to be an ectoparasitoid wood wasp that fed on wood-boring beetle larvae. Species similar in lifestyle and morphology to this ancestor still exist in the Ichneumonoidea. However, recent molecular and morphological analysis suggests this ancestor was endophagous, meaning it fed from within its host. A significant radiation of species in the Hymenoptera occurred shortly after the evolution of parasitoidy in the order and is thought to have been a result of it. The evolution of a wasp waist, a constriction in the abdomen of the Apocrita, contributed to rapid diversification as it increased maneuverability of the ovipositor, the organ off the rear segment of the abdomen used to lay eggs. The
phylogenetic tree A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
gives a condensed overview of the positions of parasitoidal groups (boldface), amongst groups (''italics'') like the Vespidae which have secondarily abandoned the parasitoid habit. The approximate numbers of species estimated to be in these groups, often much larger than the number so far described, is shown in parentheses, with estimates for the most populous also shown in boldface, like "(150,000)". Not all species in these groups are parasitoidal: for example, some Cynipoidea are phytophagous.


Taxonomy

The parasitoid wasps are
paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...
since the ants,
bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfami ...
s, and non-parasitic wasps such as the Vespidae are not included, and there are many members of mainly parasitoidal families which are not themselves parasitic. Listed are Hymenopteran families where most members have a parasitoid lifestyle. Symphyta: *
Orussidae The Orussidae or the parasitic wood wasps represent a small family of sawflies ("Symphyta"). Currently, about 93 extant and four fossil species are known. They take a key position in phylogenetic analyses of Hymenoptera, because they form the sis ...
Apocrita: *
Scolebythidae The Scolebythidae are a small family of aculeate wasps in the superfamily Chrysidoidea. These chrysidoid wasps are found in Africa, Australia, the Neotropics, north China, Thailand and Fiji. They are parasites on larvae of Cerambycidae and Ptin ...
*
Bethylidae The Bethylidae are a family of aculeate wasps in the superfamily Chrysidoidea. As a family, their biology ranges between parasitoid wasps and hunting wasps. Overview Like most of the Chrysidoidea, the Bethylidae are stinging Hymenoptera and mo ...
*
Chrysididae Commonly known as cuckoo wasps or emerald wasps, the hymenopteran family Chrysididae is a very large cosmopolitan group (over 3000 described species) of parasitoid or kleptoparasitic wasps, often highly sculptured, with brilliant metallic color ...
*
Sclerogibbidae The Sclerogibbidae are a small family of aculeate wasps in the superfamily Chrysidoidea. Overview Sclerogibbidae are ectoparasitoids of Embioptera. The female wasp oviposits an egg on the abdomen of a host. Once the larva emerges, it attaches ...
* Dryinidae *
Embolemidae Embolemidae is a family of small solitary parasitoid wasps with around 70 species in 2 genera distributed around the world.van Achterberg, Cornelis & Kats, R.. (2000). Revision of the Palaearctic Embolemidae (Hymenoptera). Zoöl. Med. 74 (2000), ...
*
Tiphiidae The Tiphiidae (also known as the tiphiid wasps) are a family of large, solitary wasps whose larvae are parasitoids of various beetle larvae, especially those in the superfamily Scarabaeoidea. Until recently, this family contained several addition ...
* Thynnidae * Sapygidae * Mutillidae * Bradynobaenidae * Chyphotidae *
Sierolomorphidae The Sierolomorphidae are a family of 13 extant species of wasps, in the genera '' Sierolomorpha'' and '' Proscleroderma'', mostly found in the Northern Hemisphere. They are rare and very little is known of their biology. A fossil species '' Lore ...
*
Braconidae The Braconidae are a family of parasitoid wasps. After the closely related Ichneumonidae, braconids make up the second-largest family in the order Hymenoptera, with about 17,000 recognized species and many thousands more undescribed. One analysis ...
*
Ichneumonidae The Ichneumonidae, also known as the ichneumon wasps, Darwin wasps, or ichneumonids, are a family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 25,000 species cur ...
* Pompilidae * Rhopalosomatidae *
Aulacidae The Aulacidae are a small, cosmopolitan family of wasps, with two extant genera containing some 200 known species. They are primarily endoparasitoids of wood wasps (Xiphydriidae) and xylophagous beetles (Cerambycidae and Buprestidae). They are c ...
*
Evaniidae Evaniidae is a family of parasitoid wasps also known as ensign wasps, nightshade wasps, hatchet wasps, or cockroach egg parasitoid wasps. They number around 20 extant genera containing over 400 described species, and are found all over the world e ...
*
Gasteruptiidae The Gasteruptiidae are one of the more distinctive families among the apocritan wasps, with surprisingly little variation in appearance for a group that contains around 500 species in two subfamilies ( Gasteruptiinae and Hyptiogastrinae) and wi ...
*
Stephanidae The Stephanidae, sometimes called crown wasps, are a family of parasitoid wasps. They are the only living members of the superfamily Stephanoidea. Stephanidae has at least 345 living species in 11 genera. The family is considered cosmopolitan in ...
* Megalyridae * Trigonalidae *
Ibaliidae The Ibaliidae are a small family of hymenopteran superfamily Cynipoidea. Ibaliidae differ from most of the cynipoids by the larvae being parasitoids on other wasp larvae in the group Siricidae. The Ibaliidae comprise three extant genera of fai ...
*
Liopteridae Liopteridae is a family of wood-boring parasitoid wasp Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps ( Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on ...
*
Figitidae Figitidae is a family of parasitoid wasps. The full diversity of this wasp family is not yet known, but about 1400 species have been described to over 130 genera. For example, the largest subfamily, Eucoilinae (previously considered as a separa ...
* Austroniidae *
Diapriidae The Diapriidae are a family of parasitoid wasps. These tiny insects have an average length of 2–4 mm and never exceed 8 mm. They typically attack larvae and pupae of a wide range of insects, especially flies. The about 2,300 described ...
*
Heloridae Heloridae is a family of wasps in the order Hymenoptera known primarily from fossils, and only one extant genus, '' Helorus'', with 12 species found worldwide. Members of ''Helorus'' are parasitic on green lacewings. Extant genera *'' Helorus'' ...
* Monomachidae * Pelecinidae * Peradeniidae *
Proctotrupidae Proctotrupidae is a family of wasps in the superfamily Proctotrupoidea of the order Hymenoptera. There are about 400 species in more than 30 genera in Proctotrupidae, found throughout most of the world. Proctotrupidae are small parasitoid wasps ...
*
Roproniidae Roproniidae is a family of wasps in the order Hymenoptera, of which only two genera are still extant, the others being fossils. Extant genera * '' Ropronia'' Provancher, 1887 * '' Xiphyropronia'' He & Chen, 1991 Fossil genera * † '' Beipiaos ...
*
Vanhorniidae Vanhorniidae is a family parasitic wasps belonging to the Proctotrupoidea. There are only two extant genera, '' Heloriserphus'' and '' Vanhornia,'' which are native to the Northern Hemisphere. They are parasitoids In evolutionary ecology, a p ...
*
Platygastridae The hymenopteran family Platygastridae (sometimes incorrectly spelled Platygasteridae) is a large group (over 4000 species) of exclusively parasitoid wasps, mostly very small (1–2 mm), black, and shining, with geniculate (elbowed) antenna ...
*
Scelionidae The hymenopteran family Scelionidae is a very large cosmopolitan group (over 3000 described species in some 176 genera) of exclusively parasitoid wasps, mostly small (0.5–10 mm), often black, often highly sculptured, with (typically) elbowe ...
*
Megaspilidae The Megaspilidae are a small hymenopteran family with 13 genera in two subfamilies, and some 450 known species, with a great many species still undescribed. It is a poorly known group as a whole, though most are believed to be parasitoids (espe ...
*
Ceraphronidae The Ceraphronidae are a small hymenopteran family with 14 genera and some 360 known species, though a great many species are still undescribed. It is a poorly known group as a whole, though most are believed to be parasitoids (especially of f ...
* Mymarommatidae *
Chalcidoidea Chalcid wasps (, , for their metallic colour) are insects within the superfamily Chalcidoidea, part of the order Hymenoptera. The superfamily contains some 22,500 known species, and an estimated total diversity of more than 500,000 species, me ...
(19 families) *
Ampulicidae The Ampulicidae, or cockroach wasps, are a small (about 170 species), primarily tropical family of sphecoid wasps, all of which use various cockroaches as prey for their larvae. They tend to have elongated jaws, pronounced neck-like constriction ...


Interactions with humans


Biological pest control

Parasitoid wasps are considered beneficial as they naturally control the population of many
pest insect Economic entomology is a field of entomology, which involves the study of insects that benefit or harm humans, domestic animals, and crops. Insects that cause losses are termed as pests. Some species can cause indirect damage by spreading diseases ...
s. They are widely used commercially (alongside other parasitoids such as tachinid flies) for
biological pest control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also i ...
, for which the most important groups are the ichneumonid wasps, which prey mainly on
caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sy ...
s of
butterflies Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprises ...
and
moths Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of w ...
; braconid wasps, which attack caterpillars and a wide range of other insects including greenfly; chalcidoid wasps, which parasitise eggs and larvae of greenfly, whitefly,
cabbage caterpillar ''Pieris brassicae'', the large white, also called cabbage butterfly, cabbage white, cabbage moth (erroneously), or in India the large cabbage white, is a butterfly in the family Pieridae. It is a close relative of the small white, ''Pieris ra ...
s, and
scale insect Scale insects are small insects of the order Hemiptera, suborder Sternorrhyncha. Of dramatically variable appearance and extreme sexual dimorphism, they comprise the infraorder Coccomorpha which is considered a more convenient grouping than th ...
s. One of the first parasitoid wasps to enter commercial use was '' Encarsia formosa'', an endoparasitic
aphelinid The Aphelinidae are a moderate-sized family of tiny parasitic wasps, with about 1100 described species in some 28 genera. These minute insects are challenging to study, as they deteriorate rapidly after death unless extreme care is taken (e.g., p ...
. It has been used to control whitefly in
greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These ...
s since the 1920s. Use of the insect fell almost to nothing, replaced by chemical pesticides by the 1940s. Since the 1970s, usage has revived, with renewed usage in Europe and Russia. In some countries, such as New Zealand, it is the primary biological control agent used to control
greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These ...
whiteflies, particularly on crops such as
tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...
, a particularly difficult plant for predators to establish on.Bioforce Limited, New Zealand
/ref> Commercially, there are two types of rearing systems: short-term seasonal daily output with high production of parasitoids per day, and long-term year-round low daily output with a range in production of 4–1000 million female parasitoids per week, to meet demand for suitable parasitoids for different crops.


In culture

Parasitoid wasps influenced the thinking of
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...
. In an 1860 letter to the American naturalist
Asa Gray Asa Gray (November 18, 1810 – January 30, 1888) is considered the most important American botanist of the 19th century. His ''Darwiniana'' was considered an important explanation of how religion and science were not necessarily mutually excl ...
, Darwin wrote: "I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars." The palaeontologist
Donald Prothero Donald Ross Prothero (February 21, 1954) is an American geologist, paleontologist, and author who specializes in mammalian paleontology and magnetostratigraphy, a technique to date rock layers of the Cenozoic era and its use to date the climate ...
notes that religiously-minded people of the
Victorian era In the history of the United Kingdom and the British Empire, the Victorian era was the period of Queen Victoria's reign, from 20 June 1837 until her death on 22 January 1901. The era followed the Georgian period and preceded the Edwa ...
, including Darwin, were horrified by this instance of evident cruelty in nature, particularly noticeable in the
Ichneumonidae The Ichneumonidae, also known as the ichneumon wasps, Darwin wasps, or ichneumonids, are a family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 25,000 species cur ...
.


Notes


References

{{Insects in culture Parasitic insects Articles containing video clips * Parasitism