Chalcid wasps (, , for their metallic colour) are

insect Insects (from Latin ') are 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 (Insect morphology#Head, head, ...

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 e ...

, 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 (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

of other insects, though other life styles are known, with the herbivorous fig wasps acting as

pollinators A pollinator is an animal that moves pollen from the male anther of a flower to the female 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 the ma ...

. Various species are used as

biological pest control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or ot ...

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,'' 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''). 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 sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

: 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 or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

, mouthparts, antennal flagella or wings.

Ecology

Most chalcidoids are parasitoids, their hosts including

insects Insects (from Latin ') are 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 jointed ...

spiders Spiders (order Araneae) are air-breathing arthropods that have eight limbs, 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 di ...

, ticks and mites, pseudoscorpions and even gall-forming

nematodes The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (he ...

. 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 fig wasps. They spend their larval stage inside the fruits of Ficus, figs. The pollinating wasps (Agaoninae, Kradibiinae, and Tetrapusiinae) are the mutualism (biology), mutualistic partners of the ...

, Epichrysomallidae, Eurytomidae, Eulophidae, Melanosomellidae, Ormyridae, Pteromalidae, Tanaostigmatidae and Torymidae. Agaonidae only develop within

figs The fig is the edible fruit of ''Ficus carica'', a species of tree or shrub in the flowering plant family Moraceae, native to the Mediterranean region, together with western and southern Asia. It has been cultivated since ancient times and i ...

. Predation is exhibited by larvae of some Encyrtidae (prey on coccid eggs) and some Eurytomidae (prey on

Cynipidae Gall wasps, also wikt:gallfly#Usage notes, traditionally 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 ...

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 plant, 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, ...

), ''Systole'' attack seeds of

Apiaceae Apiaceae () or Umbelliferae is a family of mostly aromatic flowering plants named after the type genus ''Apium,'' and commonly known as the celery, carrot, or parsley family, or simply as umbellifers. It is the 16th-largest family of flowering p ...

used as spices (e.g.

coriander Coriander (), whose leaves are known as cilantro () in the U.S. and parts of Canada, and dhania in parts of South Asia and Africa, is an annual plant, annual herb (''Coriandrum sativum'') in the family Apiaceae. Most people perceive the ...

) and '' Megastigmus'' attack seeds of

Pinaceae The Pinaceae (), or pine family, are conifer trees or shrubs, including many of the well-known conifers of commercial importance such as Cedrus, cedars, firs, Tsuga, hemlocks, Pinyon_pine, piñons, larches, pines and spruces. The family is incl ...

grown in plantations. Females of family Agaonidae are important as pollinators of figs. Some chalcidoids, especially those in genera '' Trichogramma'' ( Trichogrammatidae) and '' Nasonia'' ( Pteromalidae) are model organisms in scientific research. They have been used to study sex determination, the influence of bacterial

endosymbionts An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualistic relationship. Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root ...

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 Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

families recognized at present: *

Walker Walker or The Walker may refer to: People *Walker (given name) *Walker (surname) *Walker (Brazilian footballer) (born 1982), Brazilian footballer Places In the United States *Walker, Arizona, in Yavapai County *Walker, Mono County, California * ...

, 1846 *

Aphelinidae 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., ...

Thomson, 1876 * Azotidae Nikolskaya & Yasnosh, 1966 * Baeomorphidae Yoshimoto, 1975 (formerly Rotoitidae) * Boucekiidae Gibson, 2003 (formerly part of Pteromalidae) * Calesidae Mercet, 1929 (formerly part of Pteromalidae) * Ceidae Boucek, 1961 (formerly part of Pteromalidae) * Cerocephalidae Gahan, 1946 (formerly part of Pteromalidae) * Chalcedectidae Ashmead, 1904 (formerly part of Pteromalidae) *

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

, 1837 (formerly part of Pteromalidae) * Coelocybidae Boucek, 1988 (formerly part of Pteromalidae) * Cynipencyrtidae Trjapitzin, 1973 * Diparidae Thomson, 1876 (formerly part of Pteromalidae) * Encyrtidae

, 1837 * Epichrysomallidae Hill & Riek, 1967 (formerly part of Pteromalidae) * Eucharitidae Latreille, 1809 * Eulophidae Westwood, 1829 * Eunotidae Ashmead, 1904 (formerly part of Pteromalidae) * Eupelmidae

, 1833 * Eurytomidae

, 1832 * Eutrichosomatidae Peck, 1951 (formerly part of Pteromalidae) * Herbertiidae Boucek, 1988 (formerly part of Pteromalidae) * Hetreulophidae Girault, 1915 (formerly part of Pteromalidae) * Heydeniidae Hedqvist, 1961 (formerly part of Pteromalidae) * Idioporidae LaSalle, Polaszek & Noyes, 1997 (formerly part of Pteromalidae) *

Leucospidae The Leucospidae (sometimes incorrectly spelled Leucospididae) are a specialized group of wasps within the superfamily Chalcidoidea, that are ectoparasitoids of aculeata, aculeate wasps or bees. They are typically mimicry, mimics of bees or sting ...

Fabricius, 1775 * Lyciscidae Boucek, 1958 (formerly part of Pteromalidae) * Macromesidae Graham, 1959 (formerly part of Pteromalidae) * Megastigmidae Thomson, 1876 * Melanosomellidae Girault, 1913 (formerly part of Pteromalidae) * Metapelmatidae Boucek, 1988 (formerly part of Eupelmidae) * Moranilidae Boucek, 1988 (formerly part of Pteromalidae) *

Mymaridae The Mymaridae, commonly known as fairyflies or fairy wasps, are a family (biology), family of chalcid wasp, chalcidoid wasps found in temperate, subtropical, and tropical regions throughout the world. The family contains around 100 genera with 1, ...

Haliday, 1833 * Neanastatidae Kalina, 1984 (formerly part of Eupelmidae) * Neodiparidae Boucek, 1961 (formerly part of Pteromalidae) * Ooderidae Boucek, 1958 (formerly part of Pteromalidae) * Ormyridae Förster, 1856 * Pelecinellidae Ashmead, 1895 (formerly part of Pteromalidae) * Perilampidae Latreille, 1809 * Pirenidae Haliday, 1844 ( including Eriaporidae) (formerly part of Pteromalidae) * Pteromalidae Dalman, 1820 * Signiphoridae Ashmead, 1880 * Spalangiidae Haliday, 1833 (formerly part of Pteromalidae) * Systasidae Boucek, 1988 (formerly part of Pteromalidae) * Tanaostigmatidae Howard, 1890 * Tetracampidae Förster, 1856 * Torymidae

, 1833 * Trichogrammatidae Haliday, 1851 There are also three extinct families: *† Diversinitidae Haas, Burks & Krogmann, 2018 *† Khutelchalcididae Rasnitsyn, Basibuyuk & Quicke, 2004 *† Protoitidae Ulmer & Krogmann, 2023 Of these families, at least five are known to be artificial groups (

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

), and have been divided into several 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 Hymenoptera superfamilies