Parasitic wasp
| Parasitic wasp | ||||||||||
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Parasitic wasp |
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| Agriotype armatus | ||||||||||
| ( Curtis , 1831) |
The water wasp ( Agriotypus armatus ) is a wasp , their larvae under water at the doll or prepupa of Caddisflies parasitize them.
Only one species of the genus Agriotypus occurs in Europe , and this is the only genus of the subfamily Agriotypinae .
description
Agriotypus armatus reaches a body length of 5.2 to 6.8 millimeters, with the males being a little smaller than the females. It is predominantly monochrome, dark brown to black in both sexes and has short silvery hairs. Notwithstanding only are Tergites two to six of the abdomen, the rails (tibiae) and foot members (tarsi) of the legs, antennas , switches (palps) and the tips of the mandibles dyed reddish brown. The long, thread-like antennae consist of 23 to 28 members in the female and 30 to 36 members in the male. The wings are crystal clear and hyaline with three dark transverse bands in the fore wing (only indistinctly pronounced in the males). It lacks the small constricted cell near the base of the wing, which is present in most parasitic wasps, called areola.
The species is the only species of the genus Agriotypus and Agriotypinae in Europe that is unmistakable through a number of morphological features. The scutellum has a single, centrally (median) seated spine that is almost the same length as the scutellum. The anterior tergites of the free abdomen have a few distinct keels. As the only parasitic wasp genus, the second to fourth sternites of the free abdomen are convex and consistently sclerotized throughout in agriotype ; in all other Ichneumonoidea these are divided into a sclerotized anterior and a membranous posterior section. In addition, the second and third tergite are fused together. The claws of the tarsi are simple, long and only slightly curved, those of the hind legs about half as long as the last (fifth) tarsal link.
The larvae have the typical, maggot-like shape of the hymenoptera larvae . They have no open stigmas . Striking at the rear end is a pair of long, horn-like extensions curved upwards. Each mandible has six or more large, tooth-like projections on the top. A clearly pigmented region can be seen on both sides of the occiput.
Biology and way of life
They fly near flowing waters in spring , sometimes in flocks. After mating, the female climbs into the water on aquatic plants or stones, about 15 to 30 cm deep into the bottom of the stream. The ichneumon wasp is enveloped in a thin, silvery, shiny film of air. She looks underwater for an enclosure of caddis flies from the Goeridae and Odontoceridae families . Caddisflies of the genus Silo , as well as the genera Lithax and Goera (Goeridae) and the species Odontocerum albicorne (Odontoceridae) are named as hosts . When she finds a quiver, she mounts it and pierces the case of the caddis fly larva with her powerful, short ovipositor . However, it only lays its egg on the host if it is a pupa or prepupa (= larvae that are ready to pupate). A quiver with younger larvae is left again after scanning with the ovule. The parasitic wasp deposits the egg on the outside of the abdomen of the host larva on a small stalk, the larva is not stung. After laying eggs, the parasitic wasp can be driven to the surface of the water. She stays under water for about 15 minutes.
Quiver of the host larva
The quivers of the caddis fly larva from Silo are about 12 mm long, slightly conical and anteriorly consist of fine grains of sand. 3 to 4 larger stones are built into each side. The inner wall of the quiver is lined with woven silk. The quiver is slightly redesigned for pupation. It is attached to the base (stone) with webbing and a locking stone is attached to the mouth, but in such a way that the water can continue to flow around the larva and supply them with oxygen.
Larval development
The larvae of Agriotypus are maggot- shaped and have two long appendages behind with claw-shaped hooks at the end. The larvae initially live as ectoparasites on the caddis fly larvae and feed on their host in such a way that the vital organs are spared. The movements of the host larvae continuously supply the first four larval stages with fresh water and thus oxygen. They absorb oxygen by diffusion through the skin.
Only after about a month does the larva moult to the last, the fifth larval stage. This last larva consumes the entire interior of the host larva within a few days. The larva now spins itself into its own cocoon within the trichopteran quiver. A “waste chamber” is created in the quiver below the larvae cocoon, in which the larval skin of the host larva and the former larval skin of the ichneumon wasp lie. The larva is surrounded by air within its cocoon. It forms a peculiar breathing band that protrudes from the quiver at the front end; it is 0.7 to 1 mm wide and 10 to 30 mm (up to 50 mm) long. This breathing band is used for plastron breathing by diffusing oxygen from the water into the interior, which the larvae can breathe with the trachea. The primary air filling is absorbed from the water by fine air bubbles, for which a thin-walled, 5 to 8 mm long hydrophilic bag at the tip of the breathing band is used, which is later no longer necessary.
Eventually the pupa forms; it remains in the air-filled cocoon. In autumn the molt to the finished imago takes place; this too remains in the cocoon for the entire winter. It only hatches in spring, where it bites open the cocoon with its mandibles and removes the locking stone of the trichoptera quiver. Since it is covered by a film of air, it swims passively to the surface of the water.
Parasitized quivers of the caddis flies are easy to recognize through the tongue-shaped breathing band.
distribution
Agriotypus armatus is widespread in Europe, restricted to areas in which the hosts occur and rarely, only locally, frequently. The species has been found in Spain, France, Germany, Austria, Italy, the Czech Republic, Slovakia, Poland, England, Denmark, Sweden, Finland, Romania, Russia and the Balkans.
Individual evidence
- ↑ Agriotypinae. Retrieved May 21, 2020 .
- ^ A b c d Andrew MR Bennett (2001): Phylogeny of Agriotypinae (Hymenoptera: Ichneumonidae), with comments on the subfamily relationships of the basal Ichneumonidae. Systematic Entomology 26 (3): 329-356. doi: 10.1046 / j.0307-6970.2001.00155.x
- ^ H. Goulet, JT Huber: Hymenoptera of the world: An identification guide to families. Center for Land and Biological Resources Research, Ottawa 1993, ISBN 0-660-14933-8 , p. 399; 432.
- ↑ a b c d e f H. Bürgis: The parasitic wasp Agriotypus armatus, a caddis fly parasite . In: Nature and Museum . tape 123 , no. 5 . Frankfurt a. M. 1993, p. 140-148 .
- ↑ K. Dettner, W. Peters: Textbook of Entomology . G. Fischer, Stuttgart 1999, ISBN 3-437-25920-2 , pp. 143 .
- ^ Benjamin Messner: Successful experiments for the first filling of the larvae cocoon of Agriotypus armatus Curtis, 1832 (Hym.) With air . In: Entomological News and Reports . tape 47 , 2003, p. 103-105 ( PDF on ZOBODAT ).
- ↑ Agriotypus armatus Curtis, 1832 | Fauna Europaea. Retrieved May 21, 2020 .
- ^ K. Bjelanović, I. Živić, A. Petrović, J. Djordjević, Z. Marković: Agriotypus armatus Curtis, 1832, a parasitoid of Silo pallipes Fabricius, 1781: the first record for the Balkan Peninsula . In: Knowledge and Management of Aquatic Ecosystems . No. 414 , 2014, ISSN 1961-9502 , p. 05 , doi : 10.1051 / kmae / 2014016 ( kmae-journal.org [accessed May 21, 2020]).
Web links
- Information on Art . Trichoptera RP, the caddis fly pages by Peter J. Neu. accessed on May 23, 2020.