Spanish slug

from Wikipedia, the free encyclopedia
Spanish slug
Arion vulgaris 3.jpg

Spanish slug ( Arion vulgaris )

Systematics
Class : Snails (gastropoda)
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Family : Slugs (Arionidae)
Genre : Arion
Type : Spanish slug
Scientific name
Arion vulgaris
Moquin-Tandon , 1855

The Spanish slug ( Arion vulgaris , Syn . : Arion lusitanicus auct. Non Mabille , 1868), also known as the nasturtium , large slug or Lusitan slug , is a nudibranch . The species is considered an economically important pest in agriculture and is also harmful in home and kitchen gardens.

Description and characteristics

The Spanish slug reaches a body length of about 7 to a maximum of 12 to 15 centimeters when fully grown and sexually mature. Sexually mature individuals are, like many snails, hermaphrodites , so they have fully developed and functional female and male sexual organs. It has the typical body shape of the slugs (family Arionidae) with an oval coat that only takes up the front third of the body; beneath this is the breathing hole (pneumostome) in the front half on the right side. The color of the individuals is highly variable, there are light brown, orange, dark brown to almost black, reddish-colored and light yellow individuals, based on the coloration it is not different from the others, depending on the opinion about 50 other species of the genus Arion distinguishable. A rough assignment is possible based on the color of the young animals: These are often yellowish with a dark longitudinal band on each side of the body; this color pattern also occurs in the related species, but is rarer in these.

A reliable determination of the species is only possible on killed and prepared individuals and even then difficult and, in cases of doubt, unsafe. Genetic methods such as DNA barcoding are often used for scientific purposes today . To distinguish between the black slug Arion ater and the red slug Arion rufus , a preparation of the genital tract is necessary. In Arion vulgaris , the ligula, a lip-shaped constriction of the enlarged, external genital tract (atrium) is significantly larger than in Arion ater . Similar to Arion rufus, it is asymmetrically C-shaped, but both edges are longer and thinner than this one. In addition, in Arion vulgaris, the atrium is wider and not divided into two by a ring-shaped constriction, and the anterior (anterior) section of the oviduct is noticeably wider. Since obviously all three types can form hybrids with one another, which can be untypical or intermediate in terms of their characteristics, a reliable determination is only possible for specialists. In addition, further, possibly not yet described cryptospecies can be expected. The other, related species, however, as far as is known, rarely occur in agricultural crops or in gardens; they are more common in forests.

Naming and original occurrence

Names

The Spanish slug appears in the literature under the scientific name Arion vulgaris , introduced in 1858 by Alfred Moquin-Tandon and Arion lusitanicus , introduced in 1868 by Jules François Mabille . Arion lusitanicus is a species endemic to the Serra da Arrábida (near Lisbon , Portugal ). The name was first mistakenly applied in 1956 to the species that began to spread in Central Europe and first appeared in France and Switzerland. It was not until 1997 that a new study of Portuguese animals revealed that their characteristics differ significantly from those found in the rest of Europe, i.e. that they cannot belong to the same species. For animals that are widespread in Europe, it was proposed in 1999 and 2002 to use the name Arion vulgaris . This until then hardly noticed species was described from western France in 1855 and was considered a synonym until then. This suggestion has caught on (although some authors remain skeptical as the attribution is not based on type material of this type). The trivial name "Spanish slug", which goes back to the erroneous equation, was now widespread and continues to be used, although it now seems unlikely that Spain was actually the original home of this species.

Original home

The species was first discovered as a novel pest in a number of western and central European countries in the 1950s. Since then it has spread further east and north. Since slugs obviously have a very limited natural ability to spread, the rapid spread can only be explained by displacement by means of human transport. According to the data, it appears very likely that the species originally had a relatively small range from which it spread with human help. The first indications of novel occurrences come from England (1954), France (1955) and Switzerland (1956). However, it is difficult to reconstruct the beginning of the spread on the basis of this information, since the species could possibly have been overlooked for a long time or be mistaken for another. Therefore, attempts are being made to reconstruct the history of the spread using genetic markers.

Given the natural spread of a species, it is to be expected that the young populations on the edge of the range are genetically relatively uniform. The greatest diversity of alleles is to be expected in the home region, where the species evolved over very long periods of time. New populations are usually the result of the immigration of a few individuals, which acts as a genetic bottleneck , as the few founding individuals can only carry and pass on a small fraction of the alleles. In addition, newly established populations should not have any (or only a few) alleles and microsatellites of their own ; their genetic variability should represent a section of that of the source population. In a study in 2013, a genetic structure was determined that deviates from these assumptions, from which it was concluded that it was already very widespread in origin, with a center more in Central than in Western Europe. A later study with even more individuals and origins found relatively little genetic variability within the species and a weak but demonstrable correlation of genetic structure with geographical distribution, with populations being slightly more diverse in the west and southwest of the distribution. The overall low genetic variability is typical for newly introduced and therefore young populations. According to these authors, a homeland in the west, but outside the Iberian Peninsula , possibly in south-west France, is most likely thereafter . However, this has not been proven with certainty. Accordingly, the species in Central Europe is likely, but not with absolute certainty, a neozoon .

Spread across Europe

The snail is currently spreading further north and east as a neozoon . Since the location and size of the original area is uncertain (see the previous section), the spread in Western Europe cannot be reliably reconstructed. However, the species is still missing in most of the Iberian Peninsula, and the few records that are now available from northern Spain are probably attributed to a more recent spread.

In Germany it was first found on the German side of the Rhine, across from Basel , by G. Schmid in 1969. After that, the Spanish slug was found more frequently in Germany. As early as 1980 she settled large parts of southern Germany. Initial records in eastern Germany are much more recent, possibly due to the reduced transport and exchange of goods across the inner-German border. In Thuringia, the first observations came from house gardens in 1987 and 1989, but it did not spread more widely until the 1990s. The Spanish slug was first discovered in Austria in 1972. However, it was probably brought in much earlier and had been overlooked by then, because just a year later it caused massive damage to gardens in large parts of the Weinviertel and Marchfeld . The first specimens were found in Switzerland as early as 1960 and in Italy in 1965. The Spanish slug was first sighted in Denmark in 1991 and in Poland in 1996. She had already arrived in southern Sweden in 1975, in southern Norway in 1988 and in southern Finland in 1990.

Northeastern Europe was only reached by the species in the 2000s. Initial evidence is available for Ukraine in 2008, for Estonia in 2009, Latvia in 2010, Romania in 2012, and Lithuania in 2013.

In warm, humid weather, the reproduction of the Spanish slug can reach extreme proportions. In the summer of 2007, up to 1,000 copies per m² were counted in Great Britain. It is now the most common nudibranch and one of the most common snail species in Germany, with up to 12 specimens per m² of cultivated area.

Body, metabolism and lifestyle

Spanish slug eats a leaf
A Spanish slug that eats clover
A video of a Spanish slug eating a leaf.
Cannibalism on a dead conspecific

The food mostly consists of juicy plants and carrion. As with many snails, it is crushed with a rasping tongue (radula). The radula resembles an elastic band with microscopic teeth. This ligament is passed over a cartilaginous core. The radula teeth grate the food and transport it into the pharynx (throat) of the snail. Cannibalism is common in the Spanish slug.

The Spanish slug is feared as a pest among garden owners and farmers . The Spanish slug prefers certain plants, such as marigolds (marigold), valerian and white diptame , and pumpkin and melon plants are also popular. When there is a shortage of food, for example due to high population densities, the Spanish slug eats almost all plants. However, living parts of wild and unbred plants are generally avoided, as these contain substances that the snail avoids when alive. In many cultivated plants, these natural defense mechanisms were bred out, often deliberately, either to make them edible for humans (lettuce, vegetables) or to reduce production costs (ornamental flowers).

There is a direct relationship between body length and activity. Longer specimens are much more active than shorter ones. Under laboratory conditions, Spanish slugs spent 68% of the time resting, 27% of the time they were moving and only 4% of the time they were busy eating. Food was mostly consumed in the dark (76%). However, there were significant differences between individuals. The laboratory results largely agree with observations in the wild.

A slug's breathing hole

Mating and maturation

Copula of Arion vulgaris

Spanish slugs, like all land snails, are hermaphrodites . That is, they can mate with each other. The partners find each other by following the slime trail. If two possible partners meet, a “pairing dance” begins. The animals circle a common point very quickly in a clockwise direction and give off large amounts of mucus. In many animals, behavior ends in separation at this stage, believed to be genetically incompatible or at the wrong stage in the reproductive cycle. Finally the "dance" comes to a standstill, both animals now press their gonophores together. Both animals now turn out their atrium, the mass of which pushes them apart. On the underside (mostly invisible to the observer) the epiphallus and spermatic duct are everted. The front end of the animals shrinks a little, so that a nodding posture results. The large spermatophore formed in the epiphallus is advanced into the spermatic duct of the respective partner by means of weak pulsating movements . The animals remain almost motionless for about three to four hours. Eventually the animals begin to retract their atria, resuming the circular motion. They are then still coupled to one another via the spermatophores, which protrude about a third of their length from the duct. They are anchored in the passage by numerous rearward facing teeth. Finally, the animals separate abruptly, leaving the spermatophores in the respective partner. The entire mating sequence usually takes about four to five and a half hours. Mating usually takes place at night, but also during the day, especially in rainy weather.

A few days to weeks later, the snails lay their eggs, each with up to 225 eggs, independently of one another in several protected clutches. Clutches are laid from the end of June, with the peak in August and September, in mild years up to December. Each snail produces around 200 to 400, but no more than 500 eggs. They are placed in moist places on the surface of the ground, under plant litter or buried at depths of up to about 10 centimeters. The development time of the eggs depends on the temperature, the fastest at 20 ° C with about 30 to 37 days. However, 10 to 15 ° C are optimal for reproductive success. No development takes place above 25 ° C. The young hatch, depending on the date of oviposition, in the same year in late autumn or in February / March of the following year. You then have a body length of approx. 10 mm. They reach full body length by late summer. The Spanish slug is univoltin (one generation per year) and semelpar (only one reproductive cycle). Most animals die soon after they lay eggs, even if they are kept in the laboratory. If it does not reproduce, unfertilized adult snails can hibernate (they are then semivoltine ), which means that, as an exception, they can live up to three years. However, the normal overwintering stage is the young or, less often, the eggs. Young animals and eggs only tolerate freezing down to around −2 ° C, so they usually overwinter buried in the ground.

Natural enemies

Due to the strong secretion of a bitter mucus, the Spanish slug is usually spurned by hedgehogs or toads . It is also - compared to the great slug - comparatively less sensitive to drought.

Indian runner ducks, as well as all other domestic duck breeds that descend from the mallard, do not disdain Spanish slugs. It is now even possible to rent ducks to combat snail plagues in your own garden.

The native common burial beetle ( Pterostichus melanarius ) prefers to eat the eggs of the Spanish slug. Attempts to use the beetle in areas with a snail plague did not, however, achieve the expected success. The useful ground beetles can be attracted by a fine-grained soil structure, which is supported by mulching .

In Switzerland, the first attempts with parasitic roundworms ( nematodes ) against the Spanish slug were quite successful. The nematode Phasmarhabditis hermaphrodita is suitable for use . The bacterium Moraxella osloensis is also being discussed as a biological agent against the Spanish slug, although it can occasionally be pathogenic to humans.

In various publications the thesis is put forward that the protected Roman snail eats, among other things, the clutch of the Spanish slug. However, this is denied by other authors.

The tiger snail , also known as the tiger snail, eats the Spanish slugs and their clutch.

Combat

To prevent the damage that the Spanish slug often causes in crops, there are various forms of slug control . The following should be mentioned here: ecological methods ( predators and cultivation), physical methods ( snail fences ) and chemical methods ( slug pellets ). In addition to fighting with natural enemies, there are other options for responding to damage caused by the Spanish slug. In organic farming , the focus is on preventive measures, since chemical agents except for iron (III) phosphate may not be used.

The Spanish slug as an animal model

The slug mucosal irritation test is a promising toxicological test method for determining the tolerance of a product that is to be used for the mucous membranes . The test, in which the Spanish slug is used as an animal model , is already a reliable test method for dividing chemicals into three groups of eye-irritating substances. This is done based on the amount of slime produced and the degree of tissue destruction in the snail. When they come into contact with irritating substances, the test animals produce mucus to protect the body. The release of proteins and enzymes ( LDH and ALP ) from the skin of the animals is a measure of the tissue destruction. So far, only Belgian specimens of the Spanish slug have been used for these animal experiments . A comparative study with Swiss specimens of A. vulgaris showed that the origin of the animals is irrelevant and the same results are obtained.

An example of the use of slugs as experimental animals is the development of vaginally applied drugs. In principle, the test is suitable for solid, semi-solid and liquid formulations. The method is also suitable to replace the very controversial Draize test ("rabbit eye test ") in the future.

useful information

The Spanish slug ingests large amounts of cadmium on soils contaminated with heavy metals . Specimens that were collected from Braubach mainly accumulated the metal in the midgut, bound to a protein with a molar mass of approx. 15  kDa .

In Denmark, which was hit by a snail plague in 2007, a national strategy was drawn up against the Spanish slug. There was a proposal from the Ministry of the Environment to use the unemployed against snails.

Individual evidence

  1. ^ W. Fischer et al.: The Spanish slug in Croatia. (PDF; 391 kB). In: Club Conchylia information. 31/1999, pp. 15-17.
  2. ↑ a b With coffee beans against snail damage. at: nabu.de , accessed on February 5, 2008
  3. ↑ a b c W. Fischer, PL Reischütz: Basic remarks on the harmful snail problem . In: The soil culture. 49/1998, pp. 281-292.
  4. ^ R. Fechter, G. Falkner: Mollusks. Mosaik-Verlag, Munich 1990, ISBN 3-570-03414-3 , p. 287.
  5. ↑ Bjørn A. Hatteland, Torstein Solhøy, Christoffer Schander, Morten Skage, Ted von Proschwitz, Leslie R. Noble: Introgression and Differentiation of the Invasive Slug Arion vulgaris from Native A. ater. In: Malacologica. 58 (1-2), 2015, pp. 303-321. doi: 10.4002 / 040.058.0210
  6. ↑ Marianna Soroka, Jan Kozłowski, Andrzej Wiktor, Tomasz Kałuski: Distribution and Genetic Diversity of the Terrestrial Slugs Arion lusitanicus Mabille, 1868 and Arion rufus (Linnaeus, 1758) in Poland Based on Mitochondrial DNA. In: Folia biologica (Kraków). 57 (1-2), 2009, pp. 71-81. doi : 10.3409 / fb57_1-2.71-81
  7. ↑ Ben Rowson, Roy Anderson, James A. Turner, William OC Symondson: The Slugs of Britain and Ireland: Undetected and Undescribed Species Increase a Well-Studied, Economically Important Fauna by More Than 20%. In: PLoS ONE. 9 (3), 2014, Art. E91907. doi: 10.1371 / journal.pone.0091907
  8. ↑ a b M. Pfenninger, A. Weigand, M. Bálint, A. Klussmann-Kolb: Misperceived invasion: the Lusitanian slug (Arion lusitanicus auct. Non-Mabille or Arion vulgaris Moquin-Tandon 1855) is native to Central Europe. In: Evolutionary Applications. 7, 2014, pp. 702-713. doi: 10.1111 / eva.12177
  9. ↑ a b c Miriam A. Zemanova, Eva Knop, Gerald Heckel: Phylogeographic past and invasive presence of Arion pest slugs in Europe. In: Molecular Ecology. 25, 2016, pp. 5747-5764. doi: 10.1111 / mec.13860
  10. ↑ Species taxon summary - lusitanicus Mabille, 1868 described in Arion. AnimalBase University of Göttingen, version of March 31, 2006
  11. ^ CO Van Regteren Altena: Notes sur les limaces. 3. Sur la présence en France d'Arion lusitanicus Mabille. In: Journal de Conchyliologie. 95 (4), Paris 1955, pp. 89-99.
  12. ↑ a b Species summary for Arion vulgaris. AnimalBase University of Göttingen, version from June 5, 2011
  13. ^ M. Kerney: Atlas of the land and freshwater molluscs of Britain and Ireland. Harley Books, Colchester 1999, ISBN 0-946589-48-8 , p. 121.
  14. ^ G. Falkner, TEJ Ripken, M. Falkner: Mollusques continentaux de France. List of References and Bibliography. (= Patrimoines Naturels. 52). Museum d'Histoire Naturelle, Paris 2002, ISBN 2-85653-539-9 .
  15. ^ G. Schmid: Arion lusitanicus in Germany. In: Arch. Moll. 100/1970, pp. 95-102.
  16. ↑ Werner Westhus et al.: Invasive, alien animals and plants in Thuringia. In: Landscape conservation and nature conservation in Thuringia. 53 (4), 2016, pp. 148–191, on page 159.
  17. ↑ PL Reischütz, FJ Stojaspal: Remarkable mollusks from Eastern Austria. In: Mitt. Zool. Ges. Braunau. 13/1972, pp. 339-344.
  18. ↑ Tehokkaan leviämisen mestari. ( Memento of the original from June 9, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. The Finnish Natural History Museum at Helsinki University @1@ 2Template: Webachiv / IABot / www.fmnh.helsinki.fi
  19. ↑ J. Hagnell et al .: How to trap a slug: Commercial versus homemade slug traps. In: Crop Protection. 25/2006, pp. 212-215.
  20. ↑ A.-M. Păpureanu, H. Reise, A. Varga: First records of the invasive slug Arion lusitanicus auct. non Mabille (Gastropoda: Pulmonata: Arionidae) in Romania. In: Malacologica Bohemoslovaca. 13, 2014, pp. 6-11.
  21. ↑ a b Spanish slug conquers Berlin's gardens. In: The world . August 22, 2007.
  22. ↑ a b Foreign animal and plant species conquer Germany. Natural History Society, accessed February 5, 2008.
  23. ↑ The diet of snails. on: weichtiere.at , accessed on February 7, 2008.
  24. ↑ a b c B. Speiser: Fewer snails in a fine seedbed. (PDF; 989 kB). In: Swiss farmer. April 3, 2002.
  25. ↑ Gluttonous nudibranchs? Spanish slug - Arion lusitanicus. at: hausdernatur.de , accessed on February 5, 2008.
  26. ^ B. Grimm, K. Schaumberger: Daily activity of the pest slug Arion lusitanicus under laboratory conditions. In: Annals of Applied Biology. 141/2002, pp. 35-44. doi : 10.1111 / j.1744-7348.2002.tb00193.x
  27. ↑ Jan Kozłowski, Rafa Sionek: Mating Behavior of Arion lusitanicus Mabille, 1868 (Gastropoda, Pulmonata, Arionidae). In: Folia malacologica. 9 (4), 2001, pp. 217-221.
  28. ↑ a b Stine Slotsbo: Ecophysiology and life history of the slug, Arion lusitanicus. PhD thesis. Department of Agroecology and Department of Bioscience, Aarhus University, 2012, ISBN 978-87-92936-09-7 .
  29. ↑ B. Grimm: Life cycle and population density of the pest slug Arion lusitanicus Mabille (Mollusca: Pulmonata) on grassland. In: Malacologia. 43/2001, pp. 25-32.
  30. ^ HE Quick: Rediscovery of Arion lusitanicus in Britain. In: Proceedings of the Malacological Society of London. 29/1952, pp. 93-101.
  31. ↑ The Spanish Snail - Every Gardener's Nightmare.  ( 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. on: br-online.de , accessed on February 5, 2008.@1@ 2Template: Dead Link / www.br-online.de  
  32. ↑ "Rent an Ent" - Duck rental in the fight against nasty slugs. In: The world. August 12, 2007.
  33. ↑ Integrated control of slug damage in organic vegetable crops. DEPARTMENT for ENVIRONMENT, FOOD and RURAL AFFAIRS (UK) (Final Project Report) (PDF; 161 kB)
  34. ↑ C. Hucklenbroich: Kahlfraß in German vegetable gardens. In: The world. July 8, 2007.
  35. ↑ MJ Wilson et al .: Biocontrol of slugs in protected lettuce using the rhabditid nematode Phasmarhabditis hermaphrodita. In: Biocontrol Science and Technology. 5/1995, pp. 233-242.
  36. ↑ L. Tan, PS Grewal: Pathogenicity of Moraxella osloensis, a bacterium associated with the nematode Phasmarhabditis hermaphrodita, to the slug Deroceras reticulatum . In: Appl. Environ. Microbiol. tape 67 , no. 11 , November 2001, p. 5010-5016 , doi : 10.1128 / AEM.67.11.5010-5016.2001 , PMID 11679319 , PMC 93264 (free full text).
  37. ↑ XY Han, JJ Tarrand: Moraxella osloensis blood and catheter infections during anticancer chemotherapy: clinical and microbiologic studies of 10 cases . In: Am. J. Clin. Pathol. tape 121 , no. 4 , April 2004, p. 581-587 , doi : 10.1309 / QBB3-AVCM-GWA3-K1XK , PMID 15080311 .
  38. ↑ Robert Nordsieck: The fascinating world of the Schnegel. on: schnegel.at
  39. ^ Ghent University: Els Adriaens. Retrieved February 6, 2008.
  40. ↑ A. Adriaens, JP Remon: Gastropods as to evaluation tool for screening the irritating potency of absorption enhancers and drugs. In: Pharmaceutical Research . 16/1999, pp. 1240-1244.
  41. ↑ a b M. M. Dhondt et al: Slug species- and population-specific effects on the end points of the Slug Mucosal Irritation test. In: Toxicology in Vitro . 20/2006, pp. 448-457. PMID 16226427
  42. ↑ MM Dhondt et al: The evaluation of the local tolerance of vaginal formulations containing dapivirine using the Slug Mucosal Irritation test and the rabbit vaginal irritation test. In: European Journal of Pharmaceutics and Biopharmaceutics . 60/2005, pp. 419-425. PMID 15996583
  43. ↑ C. Callens et al.: Toxicological evaluation of a bioadhesive nasal powder containing a starch and Carbopol® 974 P on rabbit nasal mucosa and slug mucosa. In: Journal of Controlled Release . 76/2001, pp. 81-91.
  44. ↑ E. Adriaens et al .: Evaluation of the mucosal irritation potency of co-spray dried Amioca® / Poly (acrylic acid) and Amioca® / Carbopol® 974P mixtures. In: Journal of Controlled Release. 88/2003, pp. 393-399.
  45. ↑ MM Dhondt et al: The evaluation of the local tolerance of vaginal formulations, with or without nonoxynol-9, using the Slug Mucosal Irritation test. In: Sexually Transmitted Diseases . 31/2004, pp. 229-235.
  46. ↑ Animal experiments are not scientifically justifiable - Part 4. ( Memento from May 19, 2007 in the web archive archive.today ) on: tierversuchsgegner.org , version from February 6, 2008.
  47. ↑ JH Draize et al .: Methods for the study of irritation and toxicity of substances applied to the skin and mucous membranes. In: Journal of Pharmacology and Experimental Therapeutics . 82/1944, p. 377.
  48. ^ E. Adriaens et al .: Refinement of the Slug Mucosal Irritation test as an alternative screening test for eye irritation. In: Toxicology in Vitro . 19/2005, pp. 79-89.
  49. ↑ HH Janssen, R. Dallinger: Diversification of cadmium-binding proteins due to different levels of contamination in Arion lusitanicus. In: Arch Environ Contam Toxicol . 20/1991, pp. 132-137. PMID 1996905
  50. ↑ Science compact. In: The world. August 10, 2007.

literature

Web links

Commons : Spanish slug ( Arion vulgaris )  - Collection of images, videos and audio files