Hymenoptera

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Hymenoptera
Temporal range:
Ma[1]
Hymenopterans from different families; Clockwise from top-left: Red imported fire ant (Formicidae), Vespula vulgaris (Vespidae), Tenthredopsis sordida (Tenthredinidae), and Western honey bee (Apidae)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
(unranked): Holometabola
Superorder: Hymenopterida
Order: Hymenoptera
Linnaeus, 1758
Suborders
  • paraphyletic
    )
  • Apocrita (wasps, bees and ants)

Hymenoptera (Ancient Greek humenópteros (“membrane-winged”), from humḗn (“membrane”) +‎ pterón ("wing”)) is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described,[2][3] in addition to over 2,000 extinct ones.[4] Many of the species are parasitic. Females typically have a special

metamorphosis
)—that is, they have a wormlike larval stage and an inactive pupal stage before they mature.

Etymology

The name Hymenoptera refers to the wings of the insects, but the original derivation is ambiguous.

hooks. Thus, another plausible etymology involves Hymen, the Ancient Greek god of marriage, as these insects have married wings in flight. Another suggestion for the inclusion of Hymen is the myth of Melissa, a nymph with a prominent role at the wedding of Zeus.[citation needed
]

Evolution

Molecular analysis finds that Hymenoptera is the earliest branching group of Holometabola.[7]

Holometabola

Hymenoptera (sawflies, wasps)

Aparaglossata
Neuropteroidea
Neuropterida

Raphidioptera (snakeflies)

Megaloptera (alderflies and allies)

Neuroptera (Lacewings and allies)

Coleopterida

Coleoptera (beetles)

Strepsiptera (twisted-wing parasites)

Panorpida
Amphiesmenoptera

Trichoptera (caddisflies)

Lepidoptera (butterflies, moths)

Antliophora

Diptera

Mecoptera (scorpionflies)

Siphonaptera (fleas)

Hymenoptera originated in the

Alex Rasnitsyn, Michael S. Engel, and others.[9]

Phylogenetic relationships within the Hymenoptera, based on both morphology and molecular data, have been intensively studied since 2000.[10] In 2023, a molecular study[10] based on the analysis of ultra-conserved elements confirmed many previous findings and produced a relatively robust phylogeny of the whole Order. Basal superfamilies are shown in the cladogram below.

Hymenoptera
Hymenoptera

Tenthredinoidea

Xyeloidea (Triassic-present)

Pamphilioidea

Unicalcarida

Siricoidea (horntails or wood wasps)

Xiphydrioidea (wood wasps)

Cephoidea (stem sawflies)

parasitism

parasitic wood wasps)

"wasp waist"

Apocrita (ants, bees, wasps)

200mya
250mya
Symphyta
Symphyta (red bar) are paraphyletic as Apocrita are excluded.

Anatomy

Bombus muscorum drinking nectar with its long proboscis

Hymenopterans range in size from very small to large insects, and usually have two pairs of wings. Their

ocelli
.

The forward margin of the hind wing bears a number of hooked bristles, or "

hamuli
", which lock onto the fore wing, keeping them held together. The smaller species may have only two or three hamuli on each side, but the largest wasps may have a considerable number, keeping the wings gripped together especially tightly. Hymenopteran wings have relatively few veins compared with many other insects, especially in the smaller species.

In the more ancestral hymenopterans, the

eggs are laid from the base of the structure, rather than from the tip, which is used only to inject venom. The sting is typically used to immobilize prey, but in some wasps and bees may be used in defense.[8]

Hymenopteran larvae typically have a distinct head region, three thoracic segments, and usually nine or 10 abdominal segments. In the suborder

Symphyta, the larvae resemble caterpillars in appearance, and like them, typically feed on leaves. They have large chewing mandibles, three pairs of thoracic limbs, and, in most cases, six or eight abdominal prolegs
. Unlike caterpillars, however, the prolegs have no grasping spines, and the antennae are reduced to mere stubs. Symphytan larvae that are wood borers or stem borers have no abdominal legs and the thoracic legs are smaller than those of non-borers.

With rare exceptions, larvae of the suborder Apocrita have no legs and are maggotlike in form, and are adapted to life in a protected environment. This may be the body of a host organism, or a cell in a nest, where the adults will care for the larva. In parasitic forms, the head is often greatly reduced and partially withdrawn into the prothorax (anterior part of the thorax). Sense organs appear to be poorly developed, with no ocelli, very small or absent antennae, and toothlike, sicklelike, or spinelike mandibles. They are also unable to defecate until they reach adulthood due to having an incomplete digestive tract (a blind sac), presumably to avoid contaminating their environment.[8] The larvae of stinging forms (Aculeata) generally have 10 pairs of spiracles, or breathing pores, whereas parasitic forms usually have nine pairs present.[11]

Reproduction

Sex determination

Among most or all hymenopterans, sex is

haploid males. The act of fertilization is under the voluntary control of the egg-laying female, giving her control of the sex of her offspring.[8] This phenomenon is called haplodiploidy
.

However, the actual genetic mechanisms of haplodiploid sex determination may be more complex than simple chromosome number. In many Hymenoptera, sex is determined by a single gene locus with many alleles.

siblings or other close relatives. Diploid males are known to be produced by inbreeding in many ant, bee, and wasp species. Diploid biparental males are usually sterile but a few species that have fertile diploid males are known.[13]

One consequence of haplodiploidy is that females on average have more genes in common with their sisters than they do with their daughters. Because of this, cooperation among kindred females may be unusually advantageous and has been hypothesized to contribute to the multiple origins of eusociality within this order.[8][14] In many colonies of bees, ants, and wasps, worker females will remove eggs laid by other workers due to increased relatedness to direct siblings, a phenomenon known as worker policing.[15]

Another consequence is that hymenopterans may be more resistant to the deleterious effects of inbreeding. As males are haploid, any recessive genes will automatically be expressed, exposing them to natural selection. Thus, the genetic load of deleterious genes is purged relatively quickly.[16]

Thelytoky

Some hymenopterans take advantage of

Apis mellifera capensis.[21]

Wasmannia auropunctata[20] and the Cape honey bee Apis mellifera capensis.[21] In A. m. capensis, the recombination rate during meiosis is reduced more than tenfold.[21] In W. auropunctata the reduction is 45 fold.[20]

Single queen colonies of the narrow headed ant Formica exsecta illustrate the possible deleterious effects of increased homozygosity. Colonies of this species which have more homozygous queens will age more rapidly, resulting in reduced colony survival.[22]

Diet

Different species of Hymenoptera show a wide range of feeding habits. The most primitive forms are typically phytophagous, feeding on flowers, pollen, foliage, or stems. Stinging wasps are predators, and will provision their larvae with immobilised prey, while bees feed on nectar and pollen.

A huge number of species are

hyperparasitoid, with the host itself being another parasitoid insect. Habits intermediate between those of the herbivorous and parasitoid forms are shown in some hymenopterans, which inhabit the galls or nests of other insects, stealing their food, and eventually killing and eating the occupant.[8]

Classification

Symphyta, without a waist: the sawfly Arge pagana
Apocrita, with narrow waist: the wasp Vespula germanica

The Hymenoptera are divided into two groups; the

Symphyta which have no waist, and the Apocrita which have a narrow waist.[4]

Symphyta

The suborder

ocelli. The prolegs do not have crochet hooks at the ends unlike the larvae of the Lepidoptera.[4] The legs and prolegs tend to be reduced or absent in larvae that mine or bore plant tissue, as well as in larvae of Pamphiliidae.[24]

Apocrita

The

thorax. Also, the larvae of all Apocrita lack legs, prolegs, or ocelli. The hindgut of the larvae also remains closed during development, with feces being stored inside the body, with the exception of some bee larvae where the larval anus has reappeared through developmental reversion.[clarification needed] In general, the anus only opens at the completion of larval growth.[4]

Threats

Hymenoptera as a group are highly susceptible to habitat loss, which can lead to substantial decreases in species richness and have major ecological implications due to their pivotal role as plant pollinators.[25]

See also

References

  1. PMID 22723471
    .
  2. .
  3. .
  4. ^ .
  5. .
  6. ^ a b Carpenter, George Herbert (1911). "Hymenoptera" . In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 14 (11th ed.). Cambridge University Press. p. 177.
  7. PMID 27558853
    .
  8. ^ a b c d e f Howell, H.V.; Doyen, J.T.; Purcell, A.H. (1998). Introduction to Insect Biology and Diversity (2nd ed.). Oxford University Press. p. 320. .
  9. .
  10. ^ .
  11. .
  12. ^ .
  13. .
  14. .
  15. ^ Davies, N.R.; Krebs, J.R.; and West, S.A. An Introduction to Behavioral Ecology. 4th ed. West Sussex: Wiley-Blackwell, 2012. pp. 387–388
  16. OCLC 28576921.{{cite book}}: CS1 maint: multiple names: authors list (link
    )
  17. .
  18. .
  19. ^ .
  20. ^ .
  21. ^ .
  22. .
  23. .
  24. ^ Baine, Q.; Looney, C.; Monckton, S. K.; Smith, D. R.; Schiff, N. M.; Goulet, H.; Redford, A. J. (April 2022). "Biology and behavior". idtools.org. Retrieved February 15, 2024.
  25. PMID 24597216
    .

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