Trigonalidae

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Trigonalidae
Taeniogonalos gundlachii

Taeniogonalos gundlachii

Systematics
Class : Insects (Insecta)
Order : Hymenoptera (Hymenoptera)
Subordination : Waist Wasps (Apocrita)
Superfamily : Trigonaloidea
Family : Trigonalidae
Scientific name
Trigonalidae
Cresson , 1887
Pseudogonalos hahnii

The Trigonalidae are a family of hymenoptera. There they belong to the more original representatives of the waist wasps , which were previously summarized as " Legimmen " or Parasitica. The family, which is spread around the world, has around 90 species, one of which is also found in Germany. The family is remarkable for its particular way of life.

features

Trigonalidae are small to medium-sized hymenoptera (about 5 to 15 mm, exceptionally also smaller, up to 3 mm), whose shape is reminiscent of digger wasps , sometimes also of large parasitic wasps , or parrot wasps . Both the shape and the color are varied, there are slender, gracefully built as well as more compact species, they are mostly black in the basic color, but often very contrasting with white, yellow and red drawing elements. A special feature is u. a. a field of specialized white hairs or scales on the female's antennae. Most of the species are also easily recognizable by their very large, asymmetrically built mandibles, very long, six-segment maxillary palpations and the special structure of the abdomen in females. Here the ovipositor has receded and is only rudimentary and not visible from the outside. The end of the last belly plate (sternum) of the female is drawn into a thorn-like extension called the " awl ", which is used instead of the ovipositor when laying eggs. The sternas two and sometimes three of the female are very conspicuously extended downwards into an edge or point in most species. The "awl", which is usually pulled down towards the abdomen, and the edge of the second sternite thus form a pincer-shaped structure. The Trigonalidae have a very fully developed, rich wing veins with a large radial cell (according to other authors: Costalzelle) near the tip of the fore wing and usually nine other, closed cells, as well as at least two closed cells in the hind wing. Due to the relatively original construction of the wings, they can be mistaken for voices . However, they are easily distinguishable from these by the long antennae with numerous links (mostly 18 to 28 antenna segments). Another characteristic of almost all species is the structure of the thigh ring (trochanter) of the hind legs. This is not only divided into two parts, as is the case with many hymenoptera, but the posterior section (called the trochantellus) is again divided diagonally so that the section appears to be tripartite. The claws are split lengthways on all legs. The wings are clear, often with dark spots and markings.

Way of life

All species whose way of life has become known so far develop as parasitoids , mostly from other hymenoptera, more rarely from caterpillar flies (Tachinidae). With very few exceptions, the occupied host species is itself a parasitoid, so it is a parasite of a parasite, known as a hyperparasite . The type of parasitization is remarkable and almost unique in the animal kingdom. The female of the Trigonalidae does not occupy its future host with eggs at all, but uses the host or the prey of its actual host species as a vector for this purpose.

Females of the Trigonalidae lay their eggs on the underside of leaves. The female sits on the upper side of the leaf and bends its abdomen around the leaf edge, so that a narrow seam of eggs is created along the lower leaf edge. The oviposition takes place extremely quickly (one egg was observed in about two seconds in one species) and very numerous. Captured females laid around ten thousand eggs in quick succession, and even more may be possible in their lifespan in the wild. Each egg is tiny at about 0.1 millimeters in length, the eggs are flattened and usually have noticeable edges or ridges. A large number of plant species are recorded almost at random. The eggs do not develop further on the leaf surface. This only happens if they are eaten by a herbivore along with the leaf. For the species examined so far, either butterfly caterpillars or sawfly larvae ("anal caterpillars") come into question. Both mechanical damage to the egg shell during the act of eating and the special, alkaline intestinal environment are required for development. The hatching first larva bores itself through the intestinal wall into the body cavity of the caterpillar. However, there is no further development here (exception: in the case of the Australian genus Taeniogonalos , further development in one or two species also takes place optionally directly in sawfly larvae of the family Pergidae ). If the occupied caterpillar is already infested with a parasitoid (either a parasitic wasp or a caterpillar fly), the trigonalid larva bores into it (if there is none, it waits in the caterpillar). The larva now eats the parasitoid from the inside. After the third moult, the up to then almost worm-shaped and slightly sclerotized larva, which apart from a few comb-like bristles has hardly any features, changes into a conspicuous stage with a large head and long, saber-like mandibles. At this stage, as with many parasitic wasp larvae, it fights against other (hyper) parasitoid larvae that may be present in the same host, including conspecifics, so that ultimately only one trigonalid hatches per host. The covered parasitic wasp larva finally leaves the infested caterpillar and creates a web in the ground to pupate. At this stage, the trigonalid larva leaves its host (either the pupa itself or the old larvae ready to pupate as a "prepupa"), often through the eye. The host larva is always killed. In the fourth and fifth instar larvae, the trigonalid larvae continue to eat from the outside of their victim's corpse. Eventually it pupates next to this one. The finished insect (the imago) usually only hatches after a diapause, which is almost always several months long, in some species it can probably last several years in part of the population ("overlying" pupae dormancy). In species that parasitize in caterpillar flies, the trigonalids overwinter in the puparium .

Deviating from the life cycle described above, there is a second development option, which is optional for the same species, but always (obligatory) in its place for some species. Caterpillars are common prey to hunting social wasps , which they bring into their nest and feed to their larvae. If a caterpillar that is infested by Trigonalid larvae is fed, it is fed with it and then develops as a brood parasite in the wasp larvae. Hosts are numerous species of the genera Vespa , Vespula and Dolichovespula . Here, too, the larva leaves the host larva in the fourth stage after it has just pupated and continues to eat (within the cell in the honeycomb) on the remains. It then pupates in the cell, pulling in a second spun lid. When pupating itself, it also usually forms a partition to keep away from the decaying remains of the incompletely eaten wasp larva. According to observations, the hatched imago is ignored by the wasps and not controlled.

According to previous observations, Trigonalidae are not host-specific. Apparently almost every parasitoid of the caterpillars or a large number of social wasps is used depending on the offer. Some species are even known from both Tachinidae and Ichneumonidae. Most species are considered to be very rare and are almost always only found sporadically. In individual wasp nests the degree of parasitization was around 20%. In addition, there were numerous nests in the same region without any parasitism.

As a rule, Trigonalidae reproduce in two sexes. Males of the Australian Taeniogonalos venatoria are known only in exceptional cases (sex ratio about 1: 250). This species reproduces mainly through (thelytoke apomictic) parthenogenesis .

Taxonomy and systematics

For the family, the name Trigonalyidae is often found in older literature. Other spelling variants were used in the past. This was due to the uncertainty of the derivation of the generic name Trigonalis , the root of which had been interpreted differently by different authors (according to Oehlke, "Trigonalydidae" would actually have been grammatically correct).

The family is characterized by numerous apomorphic characteristics and is isolated within the hymenoptera, so that it is the only family (monotypical) in its own superfamily Trigonaloidea. Their position within the Hymenoptera is controversial. Numerous older authors suspected closer ties to the Aculeata, which are still possible today. Today, the (super) family is usually regarded as one of the most basic lines of the waist wasps due to numerous original characteristics (plesiomorphies), although their sister group relationship remains unclear. In many analyzes there are relationships to the hunger wasp-like (Evaniomorpha). A possible sister group is the Megalyridae family according to a molecular family tree based on four gene regions .

The family is divided into two subfamilies.

distribution

The Trigonalidae are distributed worldwide and have their distribution center in the tropics. Some genera can also be found almost worldwide. The family becomes rarer towards the north. In Europe only one species of the family is common, Pseudogonalos hahnii (alternatively written as "hahni"). This species is widespread in Germany and can be found in all parts of the country, it also occurs in the Netherlands.

Fossil lore

Fossils that have been assigned to the family have been around since the Cretaceous . However, the very early representatives are sometimes problematic in the assignment. It is possible that they are members of the core group, or they belong to families that are now extinct with a similar combination of characteristics as the extinct Maimetshidae. Fossils from the Tertiary that can be identified without any doubt come from the Baltic amber, for example. In Germany they were found in the Rott fossil deposit near Bonn.

swell

  • David Carmean & Lynn Kimsey (1998): Phylogenetic revision of the parasitoid wasp family Trigonalidae (Hymenoptera). Systematic Entomology, 23: 35-76. doi : 10.1046 / j.1365-3113.1998.00042.x
  • Curtis P. Clausen (1929): Biological Studies on Poecilogonalos thwaitesii (Westw.), Parasitic in the Cocoons of Henecospilus (Hymenoptera: Trigonalidae). Proceedings of the Entomological Society of Washington 31: 67-79.
  • Curtis P. Clausen (1931): Biological Notes on the Trigonalidae (Hymenoptera). Proceedings of the Entomological Society of Washington 33: 72-81.

Web links

Individual evidence

  1. ^ Philip Weinstein (1992): The biology of the parasitic wasp Taeniononalos venatoria Riek (Trigonalyidae) and its Eucalyptus-defoliating host Perga dorsalis Leach (Hymenoptera, Pergidae). Thesis, University of Adelaide.
  2. ↑ Shannon M. Murphy, John T. Lill, and David R. Smith (2009): A Scattershot Approach to Host Location: Uncovering the Unique Life History of the Trigonalid Hyperparasitoid Orthogonalys pulchella (Cresson). American Entomologist 55 (2): 82-87.
  3. ↑ David Carmean, Roger D. Akre, Richard S. Zack, Hal. C. Reed (1981): Notes On The Yellowjacket Parasite Bareogonalis canadensis. Entomological News 92: 23-26.
  4. ↑ Seiki Yamane (1973): Descriptions of the second to final instar larvae of Bareogonalos jezoensis with some notes on its biology (Hymenoptera, Trigonalidae). Kontyu 41 (2): 194-202.
  5. ↑ P. Weinstein & AD Austin (1996): Thelytoky in Taeniogonalos venatoria Riek (Hymenoptera: Trigonalyidae), with Notes on its Distribution and First Description of Males. Australian Journal of Entomology 35: 81-84.
  6. ↑ Michael J. Sharkey, James M. Carpenter, Lars Vilhelmsen, John Heraty, Johan Liljeblad, Ashley PG Dowling, Susanne Schulmeister, Debra Murray, Andrew R. Deans, Fredrik Ronquist, Lars Krogmann, Ward C. Wheeler (2012): Phylogenetic relationships among superfamilies of Hymenoptera. Cladistics 28 (2012) 80-112. doi : 10.1111 / j.1096-0031.2011.00366.x
  7. ↑ John Heraty, Fredrik Ronquist, James M. Carpenter, David Hawks, Susanne Schulmeister, Ashley P. Dowling, Debra Murray, James Munro, Ward C. Wheeler, Nathan Schiff, Michael Sharkey (2011): Evolution of the hymenopteran megaradiation. Molecular Phylogenetics and Evolution 60: 73-88. doi : 10.1016 / j.ympev.2011.04.003
  8. ↑ Joachim Oehlke (1984): Contributions to the insect fauna of the GDR: Hymenoptera - Evanioidea, Stephanoidea, Trigonalyidea. Faunistic treatises (State Museum for Animal Science in Dresden) 11 (13): 161-190.
  9. ↑ Renate Freund & Jürgen Illmer (2003): Some remarkable finds of hymenoptera (Hymenoptera) in the Wesel / Niederrhein district. Bembix 17: 8-13.
  10. ↑ Volker Haeseler (1976): Pseudogonalos hahni (Spin.) In Northern Germany. (Hym., Trigonalidae). Fauist-ecological communications 5: 43-46.
  11. ↑ SJ van Ooststroom (1969): Over het voorkomen van Pseudogonalis hahni (spin.) In Nederland. Entomological Reports 29: 123-125.
  12. ↑ A. Nel, V. Perichot, D. Neraudeau (2003): The oldest trigonalid wasp in the Late Albian amber of Charente-Maritime (SW France) (Hymenoptera: trigonalidae). Eclogae Geologicae Helvetiae 96 (3): 503-508.
  13. ↑ Alexandr P. Rasnitsyn & Denis J. Brothers (2009): New genera and species of Maimetshidae (Hymenoptera: Stephanoidea s. L.) From the Turonian of Botswana, with comments on the status of the family. African Invertebrates 50 (1): 191-204.
  14. ↑ George Poinar Jr. (2005): Fossil trigonalidae and vespidae (Hymenoptera) in baltic amber. Proceedings of the Entomological Society of Washington 107: 55-63.
  15. ↑ Georg Statz (1938): New finds of parasitic Hymenoptera from the Tertiary of Rott on the Siebengebirge. Decheniana 98 (1): 71-154.