Wetting field slug
| Wetting field slug | ||||||||||||
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Reticulated field slug ( Deroceras reticulatum ) |
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| Scientific name | ||||||||||||
| Deroceras reticulatum | ||||||||||||
| ( OV Müller , 1774) |
The net field slug or net field snail ( Deroceras reticulatum ) is a species of slug from the family of field slugs ( Agriolimacidae), which is subordinate to land snails (Stylommatophora). It is one of the most common nudibranch species in cultivated land and can cause noticeable economic damage to crops if the population is large.
features
The reticulated field snail becomes 4 to 6 cm long when it is stretched out. The basic color is mostly light brown or cream-colored and mostly dark, reticulated, hence the name. However, the color and the pattern are very variable. The color can also range from a darker brown to slate gray. There are also specimens in which the net pattern is almost completely absent, or specimens in which the net pattern converges, i.e. H. these animals are very dark, almost black. The body is roughly wrinkled, the skin appears thick-skinned (compared to other species of field snail). The breathing opening is surrounded by a slightly lighter ring. The keel is short and blunt. The sole is very light.
Reproduction
Like all field snails, the wedged field snail is a hermaphrodite, self-fertilization seems to be possible, but occurs very rarely. The development is strongly dependent on temperature and takes place in the various regions of Europe e.g. T. completely different. In cooler regions (e.g. Scandinavia) only one generation is formed per year. The animals hatch in June and become sexually mature after about three months. Mating takes place in August and September, as is the oviposition. In mild weather, the oviposition can take longer. The eggs are deposited in packages of 10 to 50 pieces. The animals withdraw into the ground, but die when the frost is severe. The eggs overwinter. In milder regions, the animals hatch from the eggs in April and May. They are then sexually mature within 2 months and fully adult at just under 3 months. The mating season can extend over the entire summer. The adults overwinter in these regions. However, they do not keep a pronounced hibernation, but are also active on mild winter days. They only retreat to protected hiding places in severe frost. The eggs are then laid under favorable conditions in February and March. Under favorable conditions, up to 300 eggs can be laid. The eggs are clear and 1.7 to 2 mm in diameter. The shape varies from spherical, oval to longitudinally elliptical. Embryonic development is highly temperature-dependent and takes 18 to 35 days. The fully developed little animals eat a hole in the egg shell and crawl out of the egg through this hole. They are 4 to 5 mm long. In these mild winter regions, the animals live to be around one year old.
Way of life, occurrence and distribution
The reticulated field snail is found practically only in cultivated land and is widespread throughout Europe. Presumably, however, it was not native to Scandinavia, but was introduced. It is rarer in southern Europe. It is the most common nudibranch species in much of Central and Western Europe. She has since been abducted worldwide.
The reticulated field snail is an omnivore. However, the species prefers fresh plant material, but also rotten plant material, algae, carrion (carcasses of smaller vertebrates, worms, insects), feces and fungi are eaten.
Harmful effect
The wedged field snail is one of the main pests in outdoor and greenhouse vegetable cultivation. Above all, it causes damage to green asparagus, as it is cultivated on clay soil and therefore offers few options for mechanical control. Most of the damage is done in the soil, i.e. at harvest time from April to the end of May. But above-ground sprouts are also attacked or eaten. The damage is mainly caused by the loss of quality. But other types of vegetables, different types of cabbage, lettuce and, above all, vegetable saplings and seedlings are damaged. It occurs as a pest every year, especially in the Benelux countries, northern France and England. In most other regions a mass increase and thus a noticeable harmful effect can only be observed occasionally.
In Switzerland, for example, it is considered to be the slug species that causes the most damage, alongside the Spanish slug . The control is carried out with the usual molluscicides or, for some years, also biologically by specifically induced infestation with the nematode Phasmarhabditis hermaphrodita . In 2001 it was found that this nematode is only a vector for the bacterium Moraxella osloensis , which has a very pathogenic effect on the net field slug.
Individual evidence
- ^ Fromming, p. 215.
- ↑ GM Barker: Molluscs as Crop Pests. 468 pp., Wallingford CABI Pub, Oxon, UK; New York, NY, 2002, ISBN 0-85199-320-6 .
- ↑ A. Ester and K. van Rozen: Effect of Nemaslug®, Salt or Carvone on the Slug Damage in Green Asparagus. Asparagus Research Newsletter, 19: 10–22, 2003 Internet edition ( PDF ).
- ↑ Slug Damage and Control of Slugs in Horticultural Crops PDF ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ B. Speiser, JG Zaller, A. Neudecker: Size-specific susceptibility of the pest slugs Deroceras reticulatum and Arion lusitanicus to the nematode biocontrol agent Phasmarhabditis hermaphrodita . In: BioControl . tape 46 , no. 3 , 2001, p. 311-320 , doi : 10.1023 / A: 1011469730322 .
- ↑ Li Tan and Parwinder S. Grewal: Pathogenicity of Moraxella osloensis, a Bacterium Associated with the Nematode Phasmarhabditis hermaphrodita, to the Slug Deroceras reticulatum. Applied and Environmental Microbiology, 67 (1): 5010-5016, Washington, DC, 2001 doi : 10.1128 / AEM.67.11.5010-5016.2001 .
literature
- Klaus Bogon: Land snails biology, ecology, biotope protection. 404 p., Natur Verlag, Augsburg 1990 ISBN 3-89440-002-1 .
- Rosina Fechter and Gerhard Falkner: molluscs. 287 pp., Munich, Mosaik-Verlag 1990 (Steinbach's Nature Guide 10), ISBN 3-570-03414-3 .
- Ewald Frömming: Biology of the Central European Landgastropods. 404 p., Duncker & Humblot, Berlin 1954.
- Michael P. Kerney, RAD Cameron & Jürgen H. Jungbluth: The land snails of Northern and Central Europe. 384 pp., Paul Parey, Hamburg.
