Fig wasp
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Fig wasps are
wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. ...
s of the superfamily Chalcidoidea which spend their larval stage inside
fig 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 world ...
s. Most are pollinators but others simply feed off the plant. The non-pollinators belong to several groups within the superfamily Chalcidoidea, while the pollinators are in the family
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 tree ...
. While pollinating fig wasps are gall-makers, the remaining types either make their own galls or usurp the galls of other fig wasps; reports of their being parasitoids are considered dubious.


History

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...
recorded in his ''
History of Animals ''History of Animals'' ( grc-gre, Τῶν περὶ τὰ ζῷα ἱστοριῶν, ''Ton peri ta zoia historion'', "Inquiries on Animals"; la, Historia Animalium, "History of Animals") is one of the major texts on biology by the ancient Gr ...
'' that the fruits of the wild fig (the
caprifig ''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family (biology), family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few spe ...
) contain ''psenes'' (fig wasps); these begin life as grubs (larvae), and the adult ''psen'' splits its "skin" (pupa) and flies out of the fig to find and enter a cultivated fig, saving it from dropping. He believed that the ''psen'' was generated spontaneously; he did not recognise that the fig was reproducing sexually and that the ''psen'' was assisting in that process.


Taxonomy

The fig wasps are a
polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...
group, including several unrelated lineages whose similarities are based upon their shared association with figs; efforts are underway to resolve the matter, and remove a number of constituent groups to other families, particularly the
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 d ...
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 phy ...
. Thus, the number of genera in the family is in flux. The family
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 tree ...
has been recently updated to include all the pollinating fig wasps and the subfamily Sycophaginae. The remaining taxa such as Epichrysomallinae, Sycoecinae, Otitesellinae, and Sycoryctinae should be included in the Pteromalidae.


Morphological adaptations

Among the Agaonidae, the female is a normal insect, while the males are mostly wingless. The males' only tasks are to mate with the females while still within the fig syconium (inverted flower) and to chew a hole for the females to escape from the fig interior. This is the reverse of
Strepsiptera The Strepsiptera are an order of insects with eleven extant families that include about 600 described species. They are endoparasites in other insects, such as bees, wasps, leafhoppers, silverfish, and cockroaches. Females of most species never ...
and the bagworm, where the male is a normal insect and the female never leaves the host. The non-pollinating wasps have developed impressive morphological adaptations in order to oviposit eggs inside the fig but from the outside: an extremely long ovipositor. Most figs (more than 600 species) have syconia that contain three types of
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s: male, short female, and long female. Female fig wasps can reach the ovaries of short female flowers with their ovipositors, but not long female flowers. Thus, the short female flowers grow wasps, and the long flowers only seeds. Contrary to popular belief, ripe figs are not full of dead wasps and the "crunchy bits" in the fruit are only seeds. The fig actually produces an enzyme called
ficain Ficain also known as ficin, debricin, or higueroxyl delabarre () is a proteolytic enzyme extracted from the latex sap from the stems, leaves, and unripe fruit of the American wild fig tree ''Ficus insipida''. Ficain was originally called ficin, a ...
(also known as ficin) which digests the dead wasps and the fig absorbs the nutrients to create the ripe fruits and seeds. Several commercial and ornamental varieties of fig are
parthenocarpic In botany and horticulture, parthenocarpy is the natural or artificially induced production of fruit without fertilisation of ovules, which makes the fruit seedless. Stenospermocarpy may also produce apparently seedless fruit, but the seeds are ac ...
and do not require pollination to produce (sterile) fruits; these varieties need not be visited by fig wasps to bear fruit.


Life cycle

The
life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring * Life-cycle hypothesis ...
of the fig wasp is closely intertwined with that of the fig tree it inhabits. The wasps that inhabit a particular tree can be divided into two groups;
pollinating Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, a ...
and non-pollinating. The pollinating wasps are part of an obligate nursery pollination mutualism with the fig tree, while the non-pollinating wasps feed off the plant without benefiting it. The life cycles of the two groups, however, are very similar. Though the lives of individual species differ, a typical pollinating fig wasp life cycle is as follows. At the beginning of the cycle, a mated mature female pollinator wasp enters the immature "fruit" (actually a stem-like structure known as a syconium) through a small natural opening (the ostiole) and
deposits A deposit account is a bank account maintained by a financial institution in which a customer can deposit and withdraw money. Deposit accounts can be savings accounts, current accounts or any of several other types of accounts explained below. ...
her eggs in the cavity. Forcing her way through the ostiole, she often loses her wings and most of her antennae. To facilitate her passage through the ostiole, the underside of the female's head is covered with short spines that provide purchase on the walls of the ostiole. In depositing her eggs, the female also deposits pollen she picked up from her original host fig. This pollinates some of the female flowers on the inside surface of the fig and allows them to mature. After the female wasp lays her eggs and follows through with pollination, she dies. After pollination, there are several species of non-pollinating wasps that deposit their eggs before the figs harden. These wasps act as parasites to either the fig or possibly the pollinating wasps. As the fig develops, the wasp eggs hatch and develop into
larva A larva (; plural larvae ) 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. After going through the pupal stage, the mature male’s first act is to mate with a female - before the female hatches. Consequently, the female will emerge pregnant. The males of many species lack wings and cannot survive outside the fig for a sustained period of time. After mating, a male wasp begins to dig out of the fig, creating a tunnel through which the females escape. Once out of the fig, the male wasps quickly die. The females find their way out, picking up pollen as they do. They then fly to another tree of the same species, where they deposit their eggs and allow the cycle to begin again.


Coevolution

The fig–wasp mutualism originated between 70 and 90 million years ago as the product of a unique evolutionary event.Herre et al. (2008) Since then, cocladogenesis and coadaptation on a coarse scale between wasp genera and fig sections have been demonstrated by both morphological and molecular studies. This illustrates the tendency towards coradiation of figs and wasps. Such strict cospeciation should result in identical phylogenetic trees for the two lineages and recent work mapping fig sections onto molecular phylogenies of wasp genera and performing statistical comparisons has provided strong evidence for cospeciation at that scale. Groups of genetically well-defined pollinator wasp species coevolve in association with groups of genetically poorly defined figs. The constant hybridization of the figs promotes the constant evolution of new pollinator wasp species.
Host switch In parasitology and epidemiology, a host switch (or host shift) is an evolutionary change of the host specificity of a parasite or pathogen. For example, the human immunodeficiency virus used to infect and circulate in non-human primates in West- ...
ing and pollinator host sharing may contribute to the incredible diversity of figs.


Genera

Fig wasps genera and classification according to the various publications: *
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 tree ...
** Agaoninae ***'' Agaon'' ***'' Alfonsiella'' ***'' Allotriozoon'' ***'' Blastophaga'' ****'' Blastophaga psenes'' ***'' Courtella'' ***'' Deilagaon'' ***'' Dolichoris'' ***'' Elisabethiella'' ***'' Eupristina'' ***'' Nigeriella'' ***'' Paragaon'' ***'' Pegoscapus'' ***''
Platyscapa ''Platyscapa'' is a genus of 19 species of pollinating fig wasps found in Africa and Madagascar, Middle East, southern Asia and the Indo-Pacific islands. They are pollinators of ''Ficus'' species belonging to subsections '' Conosycea'' and ''Uro ...
'' ***'' Pleistodontes'' ***'' Waterstoniella'' ***''
Wiebesia ''Wiebesia'' is a genus in the family Agaonidae (fig wasps). The scientific name of this genus was first published in 1988 by Boucek. Pollinating fig wasps are specific to specific figs. '' Ficus pumila var. awkeotsang,'' the source of aiyu jell ...
'' **
Kradibiinae 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 ...
***''
Ceratosolen ''Ceratosolen'' is an Old World wasp genus in the family Agaonidae (fig wasps). They are pollinators of the monoecious fig subsections ''Sycomorus'' and ''Sycocarpus'', and the section ''Neomorphe'', all belonging to the subgenus ''Sycomorus''. ...
'' ***'' Kradibia'' ** Sycophaginae ***'' Anidarnes'' ***'' Eukoebelea'' ***'' Idarnes'' ***'' Pseudidarnes'' ***'' Sycophaga'' ** Tetrapusiinae ***''
Tetrapus ''Tetrapus'' is a genus of fig wasp native to the Americas. Fig wasps have an obligate mutualism with the fig species they pollinate. ''Tetrapus'' pollinates figs in the subgenus '' Pharmacosycea''. ''Tetrapus'' appears to be the sole genus ...
'' *
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 d ...
** Colotrechinae ***'' Podvina'' ** Epichrysomallinae ***'' Acophila'' ***'' Asycobia'' ***'' Camarothorax'' ***'' Epichrysomalla'' ***'' Eufroggattia'' ***'' Herodotia'' ***'' Lachaisea'' ***'' Meselatus'' ***'' Neosycophila'' ***'' Odontofroggatia'' ***'' Parapilkhanivora'' ***'' Sycobia'' ***'' Sycobiomorphella'' ***'' Sycomacophila'' ***'' Sycophilodes'' ***'' Sycophilomorpha'' ***'' Sycotetra'' ** Otitesellinae ***'' Comptoniella'' ***'' Eujacobsonia'' ***'' Gaudalia'' ***'' Grandiana'' ***'' Grasseiana'' ***'' Lipothymus'' ***'' Marginalia'' ***'' Micranisa'' ***'' Micrognathophora'' ***'' Otitesella'' ***'' Philosycus'' ***'' Philosycella'' ***'' Walkerella'' **
Pteromalinae Pteromalinae is a parasitoid wasp subfamily in the family Pteromalidae. Genera *Otitesellini: ''Adiyodiella'', ''Apocrypta'', ''Arachonia'', ''Bouceka'', ''Comptoniella'', ''Crossogaster'', ''Diaziella'', ''Dobunabaa'', ''Eujacobsonia'', ''Gr ...
***'' Ficicola'' ***'' Hansonita'' ** Sycoecinae ***'' Crossogaster'' ***'' Diaziella'' ***'' Philocaenus'' ***'' Robertsia'' ***''
Seres Seres are the people of Serica, one of the easternmost countries of Asia known to the ancient Greeks and Romans. Seres may also refer to: People * * * Brands and enterprises * See also * Celes (disambiguation) Celes may refer to: * ...
'' ***'' Sycoecus'' ** Sycoryctinae ***'' Adiyodiella'' ***''
Apocrypta __NOTOC__ ''Apocrypta'' is an Old World genus of parasitic Ficus, fig wasps in the family Pteromalidae. They are parasitoids of gall-wasps in the Sycophagini tribe, and especially ''Ceratosolen'' species, pollinators of the ''Sycomorus'', ''Sycoca ...
'' ***'' Arachonia'' ***'' Bouceka'' ***'' Critogaster'' ***'' Dobunabaa'' ***'' Parasycobia'' ***'' Philotrypesis'' ***'' Philoverdance'' ***''
Sycoscapter ''Sycoscapter'' is a genus of non-pollinating fig wasp which is native to the Afrotropical, Indomalayan and Australasian realm The Australasian realm is a biogeographic realm that is coincident with, but not (by some definitions) the same as, ...
'' ***'' Watshamiella'' *
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 (m ...
***''
Ormyrus ''Ormyrus'' is a genus of chalcid wasps in the family Ormyridae. There are at least 120 described species in ''Ormyrus''. See also * List of Ormyrus species This is a list of 126 species in ''Ormyrus'', a genus of chalcid wasps in the family Or ...
'' * Eurytomidae ***''
Bruchophagus ''Bruchophagus'' is a genus of wasps belonging to the family Eurytomidae. The genus has cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in ...
'' ***''
Eurytoma ''Eurytoma'' is a genus of parasitoid chalcid wasps in the family 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) ...
'' ***'' Ficomila'' ***'' Syceurytoma'' ***'' Sycophila'' *
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 phy ...
***''
Megastigmus ''Megastigmus'' is a genus of minute wasps. There are more than 134 described species, more than half of which undergo larval development within the seeds of trees and shrubs. List of species * ''Megastigmus acaciae'' Noble, 1939 * ''Megastigmu ...
'' ***'' Physothorax'' ***''
Torymus ''Torymus'' is a genus of chalcid wasps from the family 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 ovipo ...
''


Museum collections

One of the world's major fig wasp collections resides in Leeds Museums and Galleries'
Discovery Centre Discovery Centre is an interactive science museum in Halifax, Nova Scotia. It is a not-for-profit charitable organization whose mission is to stimulate interest, enjoyment and understanding of science and technology. History In October 2010, th ...
, and was collected by Dr. Steve Compton.


References


Sources

* * * * * * * *


External links


Images of fig wasps on Morphbank, a biological image database
{{Hymenoptera, 2 Agaonidae Chalcidoidea Insect common names