Spanish slug
Encyclopedia
The Spanish slug, scientific name Arion vulgaris, more commonly known in English
-speaking countries under the incorrectly applied Latin
name, Arion lusitanicus, is a species
of air-breathing land slug
, a terrestrial
pulmonate gastropod mollusk in the family Arionidae, the roundback slugs.
This is a highly invasive slug species. It is often considered a pest, not only in areas where it has been accidentally introduced, but even in places where it is indigenous.
, western France and southern England, but provided no published references for these assumptions. In Britain the slug was first recorded in 1954, which does not indicate native distribution there. Reliable records from Spain probably do not exist. Moquin-Tandon described the species originally from France without exact indication of the locality, presumably western or southwestern France.
Arion vulgaris is also known from the USA since 1998.
Chronological overview of expansion of Arion vulgaris in Europe:
This species has not yet become established in the USA, but it is considered to represent a potentially serious threat as a pest, an invasive species
which could negatively effect agriculture, natural ecosystems, human health or commerce. Therefore it has been suggested that this species be given top national quarantine
significance in the USA.
Reproductive system
: The atrium is small. The oviduct is large and swollen, with the same diameter as atrium. The spermatheca is spherical, its diameter twice of oviduct. The long, anteriorly swollen oviductus with large longitudinal ligula inside is distinctive of Arion vulgaris.
When disturbed, the slugs will emit copious amounts of mucus
. When killed in boiling water (one of several methods used in the fight against the species as an invasive organism), the mucus will colour the water yellow.
It is a serious horticultural pest in large parts of Europe. It is being dispersed mainly by soil used for horticultural purposes.
species in Europe in DAISIE European Invasive Alien Species Gateway, and this is the only land gastropod among these one hundred ones. Arion vulgaris is the worst slug pest in Europe and it has an important economical, ecological, health and social impact.
The local name of the slug in the regions it has invaded is typically a translation of "Spanish slug". In recent years, as its dominance has increased, it has been nicknamed "killer slug", perhaps due to its tendency to eat dead or weaker individuals of the species, although its destructive impact on gardens may seem just as appropriate a reason for the name. The German name "Spanische Wegschnecke" for the species translates "Spanish road slug", which could be misunderstood to indicate spread along roadside vegetation. "Wegschnecke" is the German artificial name invented for the genus Arion, so all members of the genus carry this name.
The main reason behind problematic invasions of gardens by the Spanish slug is that it has adapted to a dry climate, where most eggs will dry out before hatching. The slug lays hundreds of eggs so that at least some may hatch. In the less dry regions of Northern Europe and Britain, the constraints of drought do not limit reproduction to the same degree. The species is also gregarious, allowing for mass occurrences. Like all pulmonate snails and slugs, it is a hermaphrodite
, meaning that one single slug can start an infestation. Poor control of exported produce has also been assumed to be a cause, as the main route for the slugs to spread was long time thought to have been through careless handling of imported produce from Spain
and Portugal
.
In recent years, it has been observed that the Spanish slug has bred with the indigenous black slug
Arion ater to produce a more frost-resistant variety in the more northerly regions. Danish authorities maintain that the Spanish slug, black slug
and red slug
are in fact subspecies of the same species.
when it was first reported as an invading species in France in 1956. This was most probably a case of misidentification. In slugs it is often difficult to establish good criteria for identifying species using external features or internal features, as colouration can be quite variable, and the rather plastic anatomy makes diagnostic anatomical features difficult to establish. Current consensus is that the true Arion lusitanicus is a microendemic species of the Serra da Arrábida mountains south of Lisbon, Portugal
. A close analysis of slugs from the site in Portugal
from where it was originally described by Jules François Mabille
in 1868, showed that the true A. lusitanicus differed from the central European invader in its internal anatomy, the shape of the spermatophore
and the number of chromosomes.
The invader was identified in 1997 as Arion vulgaris, which had been described by Moquin-Tandon in 1855 from an unrecorded site in France, presumably from western or southwestern France. The results of these studies were first published in a local journal in Spain. The news were not noticed outside Spain until they were mentioned in a widely dispersed atlas of British molluscs.
Still today we are confronted with the Central European invader being reported as having originally been introduced with vegetables from Spain. These reports are usually based on outdated information published in pre-1999 literature. Often this can be recognised by the name A. lusitanicus being used for the species, instead of A. vulgaris. Its common name "Spanish slug" was also based on the unsubstantiated assumption that the species would not only live in Portugal, but also in Spain. Portugal had less intensive economical trade connections with France. Actually Arion lusitanicus had never been reliably reported from Spain.
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
-speaking countries under the incorrectly applied Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
name, Arion lusitanicus, is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of air-breathing land slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
, a terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...
pulmonate gastropod mollusk in the family Arionidae, the roundback slugs.
This is a highly invasive slug species. It is often considered a pest, not only in areas where it has been accidentally introduced, but even in places where it is indigenous.
Distribution
The native distribution of Arion vulgaris is not exactly known. Some sources have claimed northern Spain in Iberian PeninsulaIberian Peninsula
The Iberian Peninsula , sometimes called Iberia, is located in the extreme southwest of Europe and includes the modern-day sovereign states of Spain, Portugal and Andorra, as well as the British Overseas Territory of Gibraltar...
, western France and southern England, but provided no published references for these assumptions. In Britain the slug was first recorded in 1954, which does not indicate native distribution there. Reliable records from Spain probably do not exist. Moquin-Tandon described the species originally from France without exact indication of the locality, presumably western or southwestern France.
Non-indigenous distribution
The non-indigenous distribution of Arion vulgaris includes whole Western Europe, Central and Northern Europe. Its distribution includes also various parts of Southern Europe and of Eastern Europe.Arion vulgaris is also known from the USA since 1998.
Chronological overview of expansion of Arion vulgaris in Europe:
- Great Britain since 1954
- France (expansion from native range) since 1955
- Switzerland since at least 1956
- Italy since 1965
- Germany since 1969
- Austria since 1971 or since 1972
- Belgium since 1973
- Poland since 1985 or since 1996
- Sweden since 1975 or since 1985
- Norway since 1988
- Finland since 1990
- Czech Republic since 1991
- Denmark since 1991 or since 2000
- Faroe IslandsFaroe IslandsThe Faroe Islands are an island group situated between the Norwegian Sea and the North Atlantic Ocean, approximately halfway between Scotland and Iceland. The Faroe Islands are a self-governing territory within the Kingdom of Denmark, along with Denmark proper and Greenland...
- established population - Latvia - established population
- Slovakia - established population
This species has not yet become established in the USA, but it is considered to represent a potentially serious threat as a pest, an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
which could negatively effect agriculture, natural ecosystems, human health or commerce. Therefore it has been suggested that this species be given top national quarantine
Quarantine
Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....
significance in the USA.
Description
The size of the adult slug is 80–120 mm. The colour of the Spanish slug is brownish or reddish brown, or brightly orange. The tentacles are darker. Colouration varies, but not within the same population. Adults differ little from Arion rufus, in contrast to the brightly coloured and banded juveniles that allow reliable determination of this species.Reproductive system
Reproductive system of gastropods
The reproductive system of gastropods varies greatly from one group to another within this very large and diverse taxonomic class of animals...
: The atrium is small. The oviduct is large and swollen, with the same diameter as atrium. The spermatheca is spherical, its diameter twice of oviduct. The long, anteriorly swollen oviductus with large longitudinal ligula inside is distinctive of Arion vulgaris.
When disturbed, the slugs will emit copious amounts of mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
. When killed in boiling water (one of several methods used in the fight against the species as an invasive organism), the mucus will colour the water yellow.
Ecology
Arion vulgaris inhabits cultivated habitats of any kind, as well as natural habitats such as river and lake margins, margins of forests, forests in valleys or moderately dry meadows. In Switzerland it has been found up to 1700 m altitude.It is a serious horticultural pest in large parts of Europe. It is being dispersed mainly by soil used for horticultural purposes.
As an invasive species
Arion vulgaris is considered among the 100 worst alienIntroduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
species in Europe in DAISIE European Invasive Alien Species Gateway, and this is the only land gastropod among these one hundred ones. Arion vulgaris is the worst slug pest in Europe and it has an important economical, ecological, health and social impact.
The local name of the slug in the regions it has invaded is typically a translation of "Spanish slug". In recent years, as its dominance has increased, it has been nicknamed "killer slug", perhaps due to its tendency to eat dead or weaker individuals of the species, although its destructive impact on gardens may seem just as appropriate a reason for the name. The German name "Spanische Wegschnecke" for the species translates "Spanish road slug", which could be misunderstood to indicate spread along roadside vegetation. "Wegschnecke" is the German artificial name invented for the genus Arion, so all members of the genus carry this name.
The main reason behind problematic invasions of gardens by the Spanish slug is that it has adapted to a dry climate, where most eggs will dry out before hatching. The slug lays hundreds of eggs so that at least some may hatch. In the less dry regions of Northern Europe and Britain, the constraints of drought do not limit reproduction to the same degree. The species is also gregarious, allowing for mass occurrences. Like all pulmonate snails and slugs, it is a hermaphrodite
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
, meaning that one single slug can start an infestation. Poor control of exported produce has also been assumed to be a cause, as the main route for the slugs to spread was long time thought to have been through careless handling of imported produce from Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
and Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
.
In recent years, it has been observed that the Spanish slug has bred with the indigenous black slug
Black slug
The black slug also known as black arion, European black slug, or large black slug, scientific name Arion ater, is a species of large land slug, a terrestrial slug in the family Arionidae, the roundback slugs.-Description:...
Arion ater to produce a more frost-resistant variety in the more northerly regions. Danish authorities maintain that the Spanish slug, black slug
Black slug
The black slug also known as black arion, European black slug, or large black slug, scientific name Arion ater, is a species of large land slug, a terrestrial slug in the family Arionidae, the roundback slugs.-Description:...
and red slug
Red Slug
The red slug, also known as the chocolate arion or the European red slug, Arion rufus, is a large land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae, the roundback slugs....
are in fact subspecies of the same species.
Confusion over species
The Spanish slug was identified as Arion lusitanicusArion lusitanicus
Arion lusitanicus, common name Portuguese slug, is a species of air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae.- Description :It is a rather large slug of reddish brown colour....
when it was first reported as an invading species in France in 1956. This was most probably a case of misidentification. In slugs it is often difficult to establish good criteria for identifying species using external features or internal features, as colouration can be quite variable, and the rather plastic anatomy makes diagnostic anatomical features difficult to establish. Current consensus is that the true Arion lusitanicus is a microendemic species of the Serra da Arrábida mountains south of Lisbon, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
. A close analysis of slugs from the site in Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
from where it was originally described by Jules François Mabille
Jules François Mabille
Jules François Mabille was a French malacologist who discovered several species of molluscs....
in 1868, showed that the true A. lusitanicus differed from the central European invader in its internal anatomy, the shape of the spermatophore
Spermatophore
A spermatophore or sperm ampulla is a capsule or mass created by males of various animal species, containing spermatozoa and transferred in entirety to the female's ovipore during copulation...
and the number of chromosomes.
The invader was identified in 1997 as Arion vulgaris, which had been described by Moquin-Tandon in 1855 from an unrecorded site in France, presumably from western or southwestern France. The results of these studies were first published in a local journal in Spain. The news were not noticed outside Spain until they were mentioned in a widely dispersed atlas of British molluscs.
Still today we are confronted with the Central European invader being reported as having originally been introduced with vegetables from Spain. These reports are usually based on outdated information published in pre-1999 literature. Often this can be recognised by the name A. lusitanicus being used for the species, instead of A. vulgaris. Its common name "Spanish slug" was also based on the unsubstantiated assumption that the species would not only live in Portugal, but also in Spain. Portugal had less intensive economical trade connections with France. Actually Arion lusitanicus had never been reliably reported from Spain.
External links
- Slug controls (on Wikibooks) Gural-Sverlova N. V. & Gural R. I. (2011). "Морфологические, анатомические и поведенческие особенности слизней из комплекса Arion lusitanicus (Arionidae) на западе Украины. [Morphological, anatomical and behavioural peculiarities of the slugs from the Arion lusitanicus complex in Western Ukraine]". Ruthenica 21(2): 97-111. PDF.