Common oak gall wasp
| Common oak gall wasp | ||||||||||||
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Common oak gall wasp ( Cynips quercusfolii ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Cynips quercusfolii | ||||||||||||
| Linnaeus , 1758 |
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The common oak gall wasp ( Cynips quercusfolii ) is a member of the gall wasp family (Cynipidae). The wasp, up to three millimeters in size, develops like most gall wasps on oak, forming typical galls on the underside of the oak leaves.
bile
The bile of the asexual generation (gall apple ) sits on veins on the underside of oak leaves. It is a spherical, green, later red colored bile with a diameter of 10 to 22 millimeters. The surface is quite smooth or has scattered small warts. The bile is fleshy and thick-walled, and when it is ripe it turns brown and shrinks. The larval chamber inside is 3 to 4 millimeters in size, with only one chamber per gall with a larva in it. When the still fleshy bile is opened, its interior turns blue-black on contact with air.
insect
The wasp is fully winged and colored black-brown to black in all parts, rarely with small reddish highlights. A recognizable suture is formed between the scutellum and the mesonotum, the front edge of the scutellum is raised in the shape of a ridge, and this also has an arched transverse furrow. On the head, the cheeks (genae) are at most half as long as the eyes, the head is slightly widened towards the back (asexual generation) or not widened (sexual generation). The claws are clearly two-toothed. The second tergite of the abdomen is elongated at the top like a tongue. On the belly side, the female wears a short, tooth-shaped extension behind.
In the asexual generation, the head and thorax are hairy long, the thirteen-link antennae are also hairy shaggy. In the gender generation, the body is largely bald. The antennae are fourteen in the female and fifteen in the male and only slightly hairy.
Way of life
The common oak gall wasp occurs in two generations in the course of the year, one reproducing bisexual and the other parthenogenetically . After mating , the female lays her eggs in the leaves of the oaks in summer, on the underside of which the well-known gall apples, which are up to two centimeters long, form. This Gallen contain within them the larva, which in the autumn chrysalis . Imaginal wasps can be found inside the bile from September. The galls usually detach from the leaf before autumn leaves fall and fall to the ground. In late autumn or winter (until January, at the latest at the beginning of February), a generation consisting exclusively of females hatches from the galls from an exposed, round hatch hole, which lay their unfertilized eggs in the tips of dormant (dormant) branch buds on the bark of older trunks. Here, too, bile develops in April / May, but it is only two to three millimeters in size and covered with reddish hair. From this bile the sex animals hatch in May to June, which are smaller than the animals of the winter generation. In the past, the representatives of the two generations were thought to be different species ( Cynips quercusfolii and Spathegaster taschenbergi ).
Cynips quercusfolii is known from numerous oak species (Quercus, Quercus section). In Central Europe these are mainly Quercus petraea and Quercus robur , as well as Quercus pubescens . in other climates, other species are significant, e.g. B. in Iran Quercus infectoria .
As is usually the case with gall wasps, this species is also heavily infested by parasitoids . In addition, other Gallwespenarten (Synergini) come as inquilines ago. In these species, the female lays her egg in the young bile of the oak gall wasp. Its larva later replaced their larvae and so does the bile for themselves. In a study in South Tyrol a inquiline (was Synergus gallaepomaeformis ) and four parasitoid chalcids TYPES ( Eurytoma brunniventris , Sycophila biguttata , Torymus nitens , Torymus cyaneus ) demonstrated. Further galls had been eaten by the weevil Curculio pyrrhoceras or chopped up by birds.
Phylogeny
A molecular study based on homologous DNA sequences revealed a related (monophyletic) genus Cynips . The closest related species (sister species) to Cynips quercusfolii is Cynips quercus .
swell
- JJ Kieffer (1914): The gall wasps (cynipids) of Central Europe, especially Germany. In: Christoph Schröder (editor): The insects of Central Europe, especially Germany. Volume III, Hymenoptera, Part 3. Frankhsche Verlagsbuchhandlung, Stuttgart. Page 1–93.
- RD Eady & J. Quinlan (1963): Hymenoptera Cynipodea. Key to families and subfamilies and Cynipinae (including galls). Handbook for the identification of British insects Vol. 8 Part 1 (a). Published by the Royal Entomological Society, London.
Individual evidence
- ↑ Mohammed-Reza Zargaran, Sargon Odisho, Farokh-Takin Babakhani, Bagher Hoseinpour (2011): Oak gall wasps (Hymenoptera: Cynipidae) species composition using diversity and similarity indexes across different locations of Oak forest, West Azerbaijan, Iran. International Journal of Biodiversity and Conservation Vol. 3 (12): 637-649.
- ↑ Klaus Hellrigl (2008): Faunistics of gall wasps from South Tyrol-Trentino (Hymenoptera: Cynipoidea). Forest Observer 4: 3-248.
- Jump up ↑ Antonis Rokas, George Melika, Yoshihisa Abe, Jose-Luis Nieves-Aldrey, James M. Cook, Graham N. Stone (2003): Lifecycle closure, lineage sorting, and hybridization revealed in a phylogenetic analysis of European oak gallwasps (Hymenoptera: Cynipidae: Cynipini) using mitochondrial sequence data. Molecular Phylogenetics and Evolution 26: 36-45.
Web links
- Cynips quercusfolii at Fauna Europaea