Garden slug
| Garden slug | ||||||||||||
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Garden slug ( Arion hortensis ) |
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| Scientific name | ||||||||||||
| Arion hortensis | ||||||||||||
| ( Férussac , 1819) |
The Garden Slug ( Arion hortensis ), and True Arion hortensis and shortly garden snail called, is a slug from the family of slugs (Arionidae) that the subordination of terrestrial snails is provided (gastropod). Basically, it is a complex of three closely related and difficult to distinguish species, which in the past were mostly united under this name. This species complex is now also known as Arion hortensis agg. designated.
features
The garden slug measures up to 50 mm in length when stretched out, but is usually much smaller. The back is dark blue to almost black with a light brownish tint. The sole is mostly brownish yellow, dark yellow to deep orange in color. the body mucus is also yellow in color. In young animals, the body is blue-gray with a darker back. The first row of wrinkles above the sole of the foot are densely speckled with snow-white pigment spots. There are also light yellow pigment spots on the dorsum. On the back and the coat there are two darker vertical stripes (bands) that are more sharply delimited at the top and more blurred at the bottom. The right bandage runs above the breathing hole. The outstretched dark tentacles have a slight tinge of reddish or purple when viewed against a light background.
The genital opening is below the slit in the jacket that leads to the breathing hole. In the genital apparatus, the atrium is divided into two parts. The free oviduct, the epiphallus and the canal of the spermathec emanate from the upper part and stand in a row. The free oviduct is relatively long and slender, and about as wide as the widest part of the epiphallus. The oviduct consists of a lower part that can be folded out and a solid, muscular upper part. The epiphallus is somewhat thickened at the base. The inner surface is covered with rows of papillae. The spermatheque is a more or less rounded structure. The stem of the spermathec is short and without thickening or swelling.
Similar species
The garden slug ( Arion hortensis ) is difficult to distinguish from the common slug ( Arion distinctus ) in terms of external characteristics . The two bands on the back and coat are closer together on the mantle of the garden slug than on the common slug. In addition, these bands run parallel on the front part of the mantle or they diverge slightly, whereas in the common slug they rather converge.
Geographical distribution and occurrence
Contrary to previous reports, the garden slug ( A. hortensis ) apparently has a limited distribution in Western Europe (the Netherlands, Belgium, France, and the westernmost part of Germany, southern Germany, northern Switzerland). In contrast, the common slug ( Arion distinctus ) seems to have a much wider distribution, which is largely identical to the earlier information for Arion hortensis agg. covers. In some regions both types occur together. Arion owenii , the third species from the Arion hortensis species complex, has so far only been found in a few regions of England. The garden slug has recently been introduced to many other temperate regions of the world, such as New Zealand, North America, South Africa and Australia. However, this evidence mostly relates to Arion hortensis agg. The species occurs in forests, bushes and in cultivated areas. In the Alps it rises up to 2000 m above sea level.
Way of life
The garden slug feeds on herbaceous, chlorophyll-rich plants, ie on fresh plant material. Fruits such as B. Strawberries are very popular. Mushrooms are also eaten less often. The animals very often also live in the ground and already eat parts of plants under the top of the soil.
The garden slug becomes sexually mature at four to six months. After mating, the eggs are laid for a period of two to three months. During this time, around five to eight clutches of 20 to around 80 eggs each are laid in the ground, around 150 to 200 eggs per animal. The eggs are cloudy, oval and measure 2.0 to 2.4 mm × 1.6 to 1.8 mm. After about 20 to 40 days, depending on the temperature, the young hatch. The average lifespan is around nine months, under ideal breeding conditions up to around 16 months. The populations in the cultural area do not have a distinct seasonal cycle. All stages can be encountered at any time. All stages can hibernate.
Systematics
Up to three species used to be united under the scientific name Arion hortensis ( Arion hortensis , Arion distinctus and Arion owenii ). This species complex is also called Arion hortensis agg in the literature . designated. Occasionally, Arion distinctus was distinguished from Arion hortensis even earlier . It cannot be ruled out that other species are hidden under this name.
Some authors divide the genus Arion into sub- genres . In this sub-genus, the three species of the Arion hortensis species complex are included in the sub-genus Kobeltia .
Harmful effect and control
The garden slug is one of the largest pests in agriculture and horticulture. According to Fromming, hardly any fresh, higher plant is spared. The damage is not only caused by the fact that seeds, seedlings, stems or shoots are eaten and the leaf area of the plants is reduced, but also by the loss of value of the vegetables or the setting plants due to damage caused by feeding, traces of slime on the plants or by stocking the vegetables Snails themselves or through their contamination with snail droppings. The places where they have eaten are often attacked by fungi and the damaged plants die secondarily from fungus attack.
Natural enemies of garden slugs are snails . Because snails, regardless of their size, eat the eggs of other snails and their offspring, they are to be viewed as beneficial insects and not as pests, especially in vegetable gardens.
The control of the garden slug is not specific to the species, but is generally directed against all species of slugs. The most efficient mechanical control method is to put up snail fences. The collection, which is also suitable for larger species of nudibranchs, is necessary for z. T. subterranean way of life and the small size of the garden slug not very effective. For combating with chemical agents, there are preparations with the active ingredients iron (III) phosphate , metaldehyde and methiocarb .
The garden slug is an intermediate host for the badger lungworm Aelurostrongylus falciformis .
literature
- Klaus Bogon: Land snails biology, ecology, biotope protection. Natur Verlag, Augsburg 1990, ISBN 3-89440-002-1 .
- Rosina Fechter, Gerhard Falkner: Mollusks. (= Steinbach's nature guide. 10). Mosaik-Verlag, Munich 1990, ISBN 3-570-03414-3 .
- Ewald Frömming: Biology of the Central European Landgastropods. Duncker & Humblot, Berlin 1954, DNB 451392302 .
- Michael P. Kerney, RAD Cameron, Jürgen H. Jungbluth: The land snails of Northern and Central Europe. Paul Parey, Hamburg / Berlin 1983, ISBN 3-490-17918-8 .
- Andrzej Wiktor: The nudibranchs of Poland Arionidae, Milacidae, Limacidae (Gastropoda, Stylommatophora). Polska Akademia Zakład Zoologii Systematycznej i Doświadczalnej Monograph Fauny Polski, I, Kraków 1973, DNB 770325319 .
Web links
Individual evidence
- ↑ a b A. J. de Winter: The Arion hortensis complex (Pulmonata: Arionidae): designation of types, descriptions, and distributional petterns, with special reference to the netherlands. In: Zoologische Mededelingen. Vol. 59, No. 1, 1984, pp. 1-17. ISSN 0024-0672
- ↑ a b Christoph Allgaier: Evidence of the coexistence of Arion hortensis Férussac 1819 and Arion distinctus Mabille 1868 (Gastropoda, Pulmonata, Arionidae) in Tübingen (Baden-Württemberg). In: Jh. Ges. Naturkde. Württemberg. 162, 2006, pp. 229-241.
- ^ A b J. Iglesias, B. Speiser: Distribution of Arion hortensis ss and Arion distinctus in Northern Switzerland. In: Journal of Molluscan Studies. 67, 2001, pp. 209-214. (Abstract)
- ↑ a b W. OC Symondson, ML Erickson, JE Liddell: Development of a Monoclonal Antibody for the Detection and Quantification of Predation on Slugs within the Arion hortensis agg. (Mollusca: Pulmonata). In: Biological Control. 16, 1999, pp. 274-282. doi: 10.1006 / bcon.1999.0764
- ↑ Engelbert Kötter: Snails in a natural garden. Cadmos Verlag, 2014, ISBN 978-3-8404-8111-6 .
- ↑ Institute for Pest Science - Control of slugs using the example of the field snail
- ^ Roy C. Anderson: Nematode Parasites of Vertebrates: Their Development and Transmission . CABI, 2000, ISBN 0-85199-786-4 , pp. 164 .