Chalcid wasps (, , for their metallic colour) are

insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, Thorax (ins ...

s within the superfamily Chalcidoidea, part of the order

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 typi ...

. The superfamily contains some 22,500 known species, and an estimated total diversity of more than 500,000 species, meaning the vast majority have yet to be discovered and described. The name "chalcid" is often confused with the name "chalcidid", though the latter refers strictly to one constituent family, the

Chalcididae The Chalcididae are a moderate-sized family within the Chalcidoidea, composed mostly of parasitoids and a few hyperparasitoids. The family is apparently polyphyletic, though the different subfamilies may each be monophyletic, and some may be ele ...

, rather than the superfamily as a whole; accordingly, most recent publications (e.g.,) use the name "chalcidoid" when referring to members of the superfamily. Most chalcid wasps are

parasitoids In evolutionary ecology, a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasitis ...

of other insects, though other life styles are known, with the herbivorous

fig wasps Fig wasps are wasps of the superfamily Chalcidoidea which spend their larval stage inside figs. Most are pollinators but others simply feed off the plant. The non-pollinators belong to several groups within the superfamily Chalcidoidea, while the ...

acting as

pollinators A pollinator is an animal that moves pollen from the male anther of a flower to the female carpel, stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are ...

. Various species are used as

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 inv ...

agents or in scientific research.

Description

Chalcidoids are generally small wasps, averaging 1.5 mm in length and usually being less than 3 mm. The body is often metallic in colour. The wings may be developed, reduced or absent. When the wings are developed, they have reduced venation or sometimes none at all. However, the group is morphologically very diverse. Chalcidoids range in size from up to 41.7 mm long (females of the pelecinellid ''

Doddifoenus wallacei ''Doddifoenus wallacei'' is a species of pteromalid wasp in the subfamily Leptofoeninae. The species is diurnal. References Pteromalidae {{Vespidae-stub ...

,'' this length includes the

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...

) to merely 0.13 mm long (males of the mymarid ''

Dicopomorpha echmepterygis ''Dicopomorpha echmepterygis'' is the smallest known insect and a species of parasitoid wasp in the family Mymaridae, which exhibits strong sexual dimorphism. The males are blind, apterous, and their body length is only 40% that of females. Wit ...

''). Various lineages have convergently evolved features such as enlarged femora, enlarged acropleura, reduced numbers of antennal and tarsal segments, reduced wings or reduced wing venation. Some have significant

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

: male fig wasps are "turtle-like fighting machines" that are very different to the females, while males of the aforementioned ''D. echmepterygis'' lack eyes,

ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-le ...

, mouthparts, antennal flagella or wings.

Ecology

Most chalcidoids are parasitoids, their hosts including

insects Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of ...

spiders Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and rank ...

, ticks and mites, pseudoscorpions and even gall-forming

nematodes The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant- parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a bro ...

. Some species parasitise a wide range of hosts, while others have a narrow host range. They attack host life stages ranging from eggs to adults. The superfamily includes primary, secondary and tertiary parasitoids, both ecto- and endoparasitoids, and both solitary and gregarious parasitoids. There are also herbivorous chalcidoids within the families of

Agaonidae The family Agaonidae is a group of pollinating and nonpollinating fig wasps. They spend their larval stage inside the fruits of figs. The pollinating wasps (Agaoninae, Kradibiinae, and Tetrapusiinae) are the mutualistic partners of the fig tre ...

, Epichrysomallidae,

Eurytomidae The Eurytomidae are a family within the superfamily Chalcidoidea. Unlike most chalcidoids, the larvae of many are phytophagous (feeding in stems, seeds, or galls), while others are more typical parasitoids, though even then the hosts are usually ...

Eulophidae The Eulophidae are a large family of hymenopteran insects, with over 4,300 described species in some 300 genera. The family includes the genus '' Elasmus'', which used to be treated as a separate family, "Elasmidae", and is now treated as a su ...

, Melanosomellidae,

Ormyridae The Ormyridae are a small family of parasitic wasps in the superfamily Chalcidoidea. They are either parasitoids or hyperparasitoids on gall-forming insects, primarily cynipid wasps and tephritid flies. The 120 or so species in three genera ( ...

Pteromalidae The Pteromalidae are a very large family of mostly parasitoid wasps, with some 3,450 described species in about 640 genera (the number was greater, but many species and genera have been reduced by synonymy in recent years). The subfamily-level di ...

, Tanaostigmatidae and

Torymidae Torymidae is a family of wasps in the superfamily Chalcidoidea. Most species in this family are small with attractive metallic coloration, and females generally have long ovipositors. Many are parasitoids on gall-forming insects, and some are ph ...

. Agaonidae only develop within

figs The fig is the edible fruit of ''Ficus carica'', a species of small tree in the flowering plant family Moraceae. Native to the Mediterranean and western Asia, it has been cultivated since ancient times and is now widely grown throughout the worl ...

. Predation is exhibited by larvae of some

Encyrtidae Encyrtidae is a large family of parasitic wasps, with some 3710 described species in about 455 genera. The larvae of the majority are primary parasitoids on Hemiptera, though other hosts are attacked, and details of the life history can be variab ...

(prey on coccid eggs) and some Eurytomidae (prey on

Cynipidae Gall wasps, also incorrectly called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this general ...

larvae).

Importance

Chalcidoidea is one of the most important taxa of biological control agents. They are used to control pest insects in both natural and agricultural ecosystems. Some herbivorous species are also used in biological control, such as the melanosomellid '' Trichilogaster acaciaelongifoliae'' for control of the weed '' Acacia longifolia''. There are also chalcidoids that are agricultural pests themselves, mainly attacking plant seeds. '' Bruchophagus'' attack seeds of legumes (e.g.

alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as ...

), ''Systole'' attack seeds of Apiaceae used as spices (e.g.

coriander Coriander (;

) and '' Megastigmus'' attack seeds of Pinaceae grown in plantations. Females of family Agaonidae are important as pollinators of figs. Some chalcidoids, especially those in genera '' Trichogramma'' ( Trichogrammatidae) and '' Nasonia'' (

) are model organisms in scientific research. They have been used to study sex determination, the influence of bacterial

endosymbionts An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within ...

and the genetics of speciation. The genome of moth parasitoid '' Copidosoma floridanum'' was sequenced as part of the i5K project.

Taxonomy

Chalcidoidea is a superfamily of

, whose family constituency is in constant flux, as new hypotheses of relationships are constantly being proposed and rejected; with the advent of

molecular systematics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

, it seems that the future will see further revisions of the classification in use today. There are fifty extant families recognized at present: *

Walker, 1846 * Aphelinidae Thomson, 1876 * Azotidae Nikolskaya & Yasnosh, 1966 * Baeomorphidae Yoshimoto, 1975 (formerly Rotoitidae) * Boucekiidae Gibson, 2003 (formerly part of

) * Calesidae Mercet, 1929 (formerly part of

) * Ceidae Boucek, 1961 (formerly part of

) * Cerocephalidae Gahan, 1946 (formerly part of

) * Chalcedectidae Ashmead, 1904 (formerly part of

) *

Latreille, 1817 * Chrysolampidae Dalla Torre, 1898 (formerly part of

Perilampidae The Perilampidae are a small family within the Chalcidoidea, composed mostly of hyperparasitoids. The family is closely related to the Eucharitidae, and the eucharitids appear to have evolved from within the Perilampidae, thus rendering the fam ...

) * Cleonymidae Walker, 1837 (formerly part of

) * Coelocybidae Boucek, 1988 (formerly part of

) * Cynipencyrtidae Trjapitzin, 1973 * Diparidae Thomson, 1876 (formerly part of

) *

Walker, 1837 * Epichrysomallidae Hill & Riek, 1967 (formerly part of

) *

Eucharitidae The Eucharitidae are a family of parasitic wasps.Ayre, G.L. Pseudometagea schwarzii (Ashm.) (Eucharitidae: Hymenoptera), a parasite of Lasius neoniger Emery (Formicidae: Hymenoptera). Canadian Journal of Zoology 40 (1962) : 157-164. Eucharitid ...

Latreille, 1809 *

Westwood, 1829 * Eunotidae Ashmead, 1904 (formerly part of

) * Eupelmidae Walker, 1833 *

Walker, 1832 * Eutrichosomatidae Peck, 1951 (formerly part of

) * Herbertiidae Boucek, 1988 (formerly part of

) * Hetreulophidae Girault, 1915 (formerly part of

) * Heydeniidae Hedqvist, 1961 (formerly part of

) * Idioporidae LaSalle, Polaszek & Noyes, 1997 (formerly part of

) * Leucospidae Fabricius, 1775 * Lyciscidae Boucek, 1958 (formerly part of

) * Macromesidae Graham, 1959 (formerly part of

) *

Megastigmidae Megastigmidae is a family of chalcid wasps in the order Hymenoptera. There are about 12 genera and more than 170 described species in Megastigmidae. Megastigmidae was formerly considered a subfamily of the family Torymidae Torymidae is a famil ...

Thomson, 1876 * Melanosomellidae Girault, 1913 (formerly part of

) * Metapelmatidae Boucek, 1988 (formerly part of Eupelmidae) * Moranilidae Boucek, 1988 (formerly part of

) * Mymaridae Haliday, 1833 * Neanastatidae Kalina, 1984 (formerly part of Eupelmidae) * Neodiparidae Boucek, 1961 (formerly part of

) * Ooderidae Boucek, 1958 (formerly part of

) *

Förster, 1856 * Pelecinellidae Ashmead, 1895 (formerly part of

) *

Latreille, 1809 * Pirenidae Haliday, 1844 ( including Eriaporidae) (formerly part of

) *

Dalman, 1820 * Signiphoridae Ashmead, 1880 * Spalangiidae Haliday, 1833 (formerly part of

) * Systasidae Boucek, 1988 (formerly part of

) * Tanaostigmatidae Howard, 1890 * Tetracampidae Förster, 1856 *

Walker, 1833 * Trichogrammatidae Haliday, 1851 There are also two extinct families: * Khutelchalcididae Rasnitsyn, Basibuyuk & Quicke, 2004 * Diversinitidae Haas, Burks & Krogmann, 2018 Of these families, at least five are known to be artificial groups (

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 ...

), and are being - or will be - divided into several families, or perhaps fused with existing families. The most problematic, the Pteromalidae, has recently been split into 24 families, and Eupelmidae into three families.

Identification

* Key to families Grissell, E. E., and M. E. Schauff. 1990. ''A handbook of the families of Nearctic Chalcidoidea (Hymenoptera).''Entomological Society of Washington (Washington, D.C.) Handbook 1:1-85. Online a

* Gibson, G. A. P., Huber, J. T., and J. B. Woolley. 1997. ''Annotated keys to the genera of Nearctic Chalcidoidea (Hymenoptera).'' NRC Research Pres

References

External links

Universal Chalcidoid DatabaseImages of chalcidoids on MorphBank, a biological image database
Pictorial overview. {{Authority control Chalcidoidea, Biological pest control wasps