Teat gall fly
| Teat gall fly | ||||||||||||
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Agathomyia wankowiczii , female |
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| Scientific name | ||||||||||||
| Agathomyia wankowiczii | ||||||||||||
| Schnabl , 1884 |
The Zitzengallen- or fungal bile fly ( Agathomyia wankowiczii ) is a fly species from the genus Agathomyia in the family of platypezidae (Platypezidae). It is known for the formation of teat-shaped galls on the underside of the flat lacquer pore ( Ganoderma applanatum ), a pore fungus .
features
The teat gall flies are flies with a body size of 4.3 millimeters for the males and 4.7 to 5.0 millimeters for the females. They show a sexual dimorphism , whereby the males are slightly darker than the females and have larger complex eyes that touch centrally.
With a black-gray color, the head is significantly darker than the chest and abdomen. The eyes are reddish-brown, especially in the lower third, the antennae yellow, whereby the third antenna segment is significantly larger than the first two and carries a thread-like flagellum. The bristles of the antenna are black like those of the entire head, whereas the labium and palpus are yellow .
The chest section is slightly arched on the back and forms a hump. It is yellow-orange in color, with the side surfaces ( pleures ) being significantly lighter; the bristles are brown to black.
The wings are transparent yellow and streaked with a characteristic, brown wing veining. One of the wing cells is clearly darkened. The holder is orange. The legs are also yellow-orange with light yellow and brown spots. The thigh ( femur ) of the front legs has a long bristle that is a quarter of the length of the lower leg ( tibia ). These are slightly curved on all legs and also have several clearly recognizable bristles. Males and females differ in the length and configuration of these bristles. The foot phalanx ( tarsi ) of the last pair of legs are widened like other goblin flies.
The first six segments of the abdomen are yellow-orange like the thorax, the segments in front of the genitals are distinctly darker to black. The male genitals are brown-yellow and are wrapped under the abdomen, the females have a yellow egg-laying apparatus ( ovipositor ).
distribution and habitat
The distribution of the teat gall fly is coupled with the distribution of the flat lacquer due to its dependence on the host fungus and is accordingly limited to deciduous and mixed deciduous forests. Although the flat lacquer sprout occurs in the temperate zones of North America, the spread of the flies is limited to Europe and North Asia. The distribution area extends from the Netherlands through Germany , Denmark , Sweden , Austria and Switzerland , Poland , Hungary and the Czech Republic to the Balkans . In the territory of the former Soviet Union , finds are documented both in the European part ( Moscow , Saint Petersburg ) and in the Amur region in Asia. Because the flies only appeared in the western Netherlands and Belgium in the last 50 years, it is assumed that the range of flies will expand to the west. There have only been six teat gall finds in Great Britain so far, so there is probably no natural distribution there.
In Central and Eastern Europe, the teat gall fly is relatively common in areas with the flat lacquer, especially when approaching the mushrooms and in their immediate vicinity. Often only individual finds or indirect evidence of fungal galls are available from other areas.
Larval development
The larval development of the flies takes place in teardrop-shaped galls on the underside of the flat lacquer sprout, which forms perennial fruiting bodies. It turned out that the larvae of this species feed exclusively on this fungus ( monophagy ).
The approach to the mushrooms and the laying of eggs begin in early summer and last about four weeks. The females are likely to find the mushrooms optically primarily through the white bulges of fresh mycelium that develop on the mushrooms at this time. This theory is supported by the observation that the approach is always directed at these ridges and the females settle there. Accordingly, only those mushrooms are selected whose mycelial structure falls during the egg ripening period in the female flies. How the flies distinguish the Flat Lacquer from other similar species with the same mycelial structure has not yet been clarified; chemical stimuli probably play a role here.
The developing larvae are slice-shaped , broadly flattened and equipped with bristles. Due to the very thin chitin shell of the body, they are white with brown banding at the segment boundaries, are a maximum of five to six millimeters long and feed on the mycelium of the bile layer. The development time from egg to pupa is between 34 and 75 days, with three larval stages being formed. There is no synchronous larval development, so there are always larvae of several stages in the fungus. From July to August, the larvae of the first generation of the year drop to the ground through a hole formed on the underside of the galls and bury themselves there to pupate , which lasts between four and 17 days. However, only about 10 percent of these pupae form a new generation, the rest lapse into dormancy and overwinter in the ground. The second generation of larvae develops from late August to October.
Biliary formation
The formation of galls on fungi is atypical; In Central Europe, the flat lacquer is the only type of fungus characterized by it. Bile formation is induced by the female laying eggs, although the exact cause has not yet been clarified. About a week after egg-laying, the fungus closes its pores in the affected area and forms a lenticular bile from the trama . The tube layer that contains the spores of the fungus is closed by the gall tissue at this point; if there is a large area of gall, the sporulation is completely absent . Below the bile, the fungus develops a hard top layer of chitin that is about 0.2 millimeters thick. After the larvae have left the galls in autumn, the gall cavities are again filled with fungal material, and the next tube layer is formed below the galls for the following year. In this way, several generations of bile can be detected in old consoles , a count of up to 600 galls on a fungus over several years.
Competitors and enemies
Fungal mycelia are the main source of food for a number of insect species ( mycetophagy ), so there are many food competitors . It is above all the larvae and adult individuals ( imago ) of various beetles, especially the sponge beetles (Ciidae), especially Cis nitidus . In addition, there are the larvae of various moth species as well as other fly and mosquito larvae . According to the findings of Walter Rühm and G. Strübing, competition with the larvae of the real moth Morophagus boleti , which eat the base of the galls, often leads to the death of the larvae of the teat gall flies . Overall, however, the competitive pressure is judged to be rather low.
There are no known predators who hunt the larvae in the galls. It can be assumed that various insects of the ground fauna , such as ground beetles (Carabidae) or ants (Formicidae) eat the pupae in the ground. Like other small insects, adult flies are also preyed on by larger insectivorous animals such as spiders , beetles and other flies. Specific parasitoids are also not known.
Taxonomy
The first mention of the teat gall fly as Agathomyia wankowiczii comes from Johann Andreas Schnabl in 1884, who described the female of this species as Callomyia wankowiczii . 1903 was taxon of Mario Bezzi synonymous with the type Agathomyia aurantiaca in the genre Agathomyia transferred. In 1904 Leander Czerny described the male of the species and restored its independence from A. aurantiaca . A comprehensive description of the animals was given in 1960 by Willi Hennig . However, it was not until 1962 that H. Weidner and F. Schremmer, with the collaboration of Hennig, were able to uncover the connection between the teat galls on the Flat Lackporling and the larvae of the flies.
literature
- W. Rühm, G. Strübing: Biocenotic connexes in tree-colonizing fungi: The Lackporling Ganoderma applanatum (Pers., Per SF Gray) and the monophageous teat gall fly Agathomyia wankowiczi Schnabl, 1884. In: Applied Zoology. 4/93, 1993.
- I. Eisfelder, K. Herschel: Agathomyia wankowiczi Schnabl, the teat gall fly from Ganoderma applanatum. In: Westphalian mushroom letters. Volume 6, 1967, pp. 5-10. (PDF)
- PJ Chandler: The Flat-footed Flies (Diptera: Opetiidae and Platypezidae) of Europe. (= Fauna Entomologica Scandinavica. 36). Leiden 2001, ISBN 90-04-12023-8 .
- H. Weidner, F. Schremmer: On the history of research, on the morphology and biology of the larva of Agathomyia wankowieczi Schnabl, a diptera larva that produces galls on tree fungi. In: Ent. zool. Mus. Hamburg 1962 2, 1962, pp. 355-366.
