Arion Vulgaris Research Articles

Prevalence and parasite load of nematodes and trematodes in an invasive slug and its susceptibility to a slug parasitic nematode compared to native gastropods

The invasive slug Arion vulgaris (Gastropoda: Arionidae) is an agricultural pest and serious nuisance in gardens of Central and Northern Europe. To investigate if the success of A.vulgaris in Norway can be attributed to a release from parasites, we compared the prevalence and parasite load of nematodes and trematodes in A. vulgaris to that of three native gastropod species, A. circumscriptus, A. fasciatus and Arianta arbustorum, in SE Norway. We found A. vulgaris to have the highest prevalence of both parasite groups (49% nematodes, 76% trematodes), which does not support the parasite release hypothesis, but rather points to A. vulgaris as a potentially important intermediate host of these parasites. For trematodes the number of individuals (parasite load) did not differ among host species; for nematodes it was higher in A. vulgaris than A. fasciatus. To further compare the parasite susceptibility of the surveyed gastropods, we exposed A. vulgaris, A. fasciatus, and A. arbustorum to a slug parasitic nematode, Phasmarhabditis hermaphrodita, in the laboratory. This nematode is commercially available and widely used to control A. vulgaris. The non-target species A. fasciatus was most affected, with 100% infection, 60% mortality and significant feeding inhibition. A. vulgaris was also 100% infected, but suffered only 20% mortality and little feeding inhibition. The load of P. hermaphrodita in infected specimens was not significantly different for the two Arion species (median: 22.5 and 45, respectively). Only 35% of A. arbustorum snails were infected, none died, and parasite load was very low (median: 2). However, they showed a near complete feeding inhibition at highest nematode dose, and avoided nematode-infested soil. Our results indicate that A. vulgaris may be less susceptible to P. hermaphrodita than the native A. fasciatus, and that non-target effects of applying this nematode in fields and gardens should be further investigated.

The potential antifeedant activity of lichen-forming fungal extracts against the invasive Spanish slug (Arion vulgaris)

The protection of horticultural crops from slug feeding can be achieved using slug pellets; however, application of molluscicides is not always safe for the environment. There is a need for alternative methods to reduce the palatability of crop plants. Chemical properties of secondary compounds from lichens influence the feeding behaviour of slugs. Liquid extracts of three lichen species (Cladonia rangiferina (L.) F.H. Wigg., Cladonia stellaris (Opiz) Pouzar & Vězda, and Pseudevernia furfuracea (L.) Zopf) were applied to three different crops and tested for their antifeedant properties against an important agricultural pest, the Spanish slug (Arion vulgaris Moquin-Tandon, 1855). All three extracts had specific activity, showing a decrease in grazing intensity as well as slug mass loss after feeding on treated food. Slugs significantly gained mass after feeding under control condition; however, they did not gain mass when fed on extract-treated food. The most effective extract was from P. furfuracea. We propose to use properties of lichen extracts to develop new environmentally friendly molluscicides.

Испан шырышты ұлуының (Arion vulgaris Moquin-Tandon, 1855) таралу аймағының географиялық кеңеюі

The article provides information about the most dangerous Spanish slimy snails that entered the territory of Kazakhstan. At the beginning of July 2020, we first met the Spanish slug (Arion vulgaris) in the Medeu State Regional Natural Park. Slimy snails predominate in the moist areas of the lower slopes of the mountains. They crowd out and replace other native animals. These species are a natural threat to local snails. Therefore, experiments were carried out on an area of 10 m2 to test biological agents against the Spanish snail (Arion vulgaris). According to the results of industrial tests, the biological preparation Bitoxibacillin (Bacillus thuringiensis var.) Showed a biological effect of 7 days — 74.9 and 7 days — 87.4 compared to the untreated control area. The biological product Aktarofit showed high biological effectiveness, providing 100% removal of Spanish mucus on the 1st day after treatment. Today, due to the annual increase in trade with foreign countries, the country has the possibility of spreading various types of pests. Therefore, to prevent these problems, further monitoring is needed to improve control of Spanish snails.

DISTRIBUTION AND POPULATION STATUS OF THE SPANISH SLUG IN ZHYTOMYR

In Zhytomyr, the Spanish slug was first discovered in 2018. The study found that the population of Spanish slugs in Zhytomyr occupied an area of 72670 m2. In all cases, numerous plants damage was recorded in the habitats of the Spanish slug. The slugs were located below the leaves and on the soil in the bush of ruderal species. In some cases, their presence could be established by the presence of orange slime on the leaves of the plants. In the study areas, other species of terrestrial molluscs occurred near the Spanish slug: Arion fasciatus (Nilsson, 1823), Arion fuscus (O. F. Müller, 1774), Limax maximus Linnaeus, 1758, Cepaea vindobonensis Ferussac, 1821 and Helix pomatia Linnaeus, 1758.Next year, the area occupied by this population increased to 92300 m2 at the expense of adjacent territories with favorable living conditions. Due to the fact that the spring of 2019 was quite cold, the slugs began to appear only in early May. As in the first population, other species of terrestrial molluscs occurred near the Spanish slug in the studied areas. In addition, a new population of 52790 m2 was discovered in 2019. That is, compared to 2018, the area covered by the invasion of Spanish slugs in Zhytomyr has doubled (145090 m2). Such high growth rates of the area occupied by the population of the Spanish slug, indicate its active settlement in the territory of Zhytomyr. In the near future, it is expected that it will appear in other biotopes suitable for the existence of this species in the city.

Cadmium Pathways in Snails Follow a Complementary Strategy between Metallothionein Detoxification and Auxiliary Inactivation by Phytochelatins.

Metal detoxification is crucial for animals to cope with environmental exposure. In snails, a pivotal role in protection against cadmium (Cd) is attributed to metallothioneins (MTs). Some gastropod species express, in a lineage-specific manner, Cd-selective MTs devoted exclusively to the binding and detoxification of this single metal, whereas other species of snails possess non-selective MTs, but still show a high tolerance against Cd. An explanation for this may be that invertebrates and in particular snails may also synthetize phytochelatins (PCs), originally known to be produced by plants, to provide protection against metal or metalloid toxicity. Here we demonstrate that despite the fact that similar mechanisms for Cd inactivation exist in snail species through binding of the metal to MTs, the actual detoxification pathways for this metal may follow different traits in a species-specific manner. In particular, this depends on the detoxification capacity of MTs due to their Cd-selective or non-specific binding features. In the terrestrial slug Arion vulgaris, for example, Cd is solely detoxified by a Cd-selective MT isoform (AvMT1). In contrast, the freshwater snail Biomphalaria glabrata activates an additional pathway for metal inactivation by synthesizing phytochelatins, which compensate for the insufficient capacity of its non-selective MT system to detoxify Cd. We hypothesize that in other snails and invertebrate species, too, an alternative inactivation of the metal by PCs may occur, if their MT system is not Cd-selective enough, or its Cd loading capacity is exhausted.

A comprehensive phylogeographic study of Arion vulgaris Moquin-Tandon, 1855 (Gastropoda: Pulmonata: Arionidae) in Europe

Arion vulgaris Moquin-Tandon, 1855 is regarded as one of the 100 most invasive species in Europe. The native distribution range of this species is uncertain, but for many years, the Iberian Peninsula has been considered as the area of origin. However, recent studies indicate that A. vulgaris probably originated from France. We have investigated the genetic structure of 33 European populations (Poland, Norway, Germany, France, Denmark, Switzerland) of this slug, based on two molecular markers, mitochondrial cytochrome c oxidase subunit I (COI, mtDNA) and nuclear zinc finger (ZF, nDNA). Our investigation included published data from two previous studies, giving a total of 95 populations of A. vulgaris from 26 countries. This comprehensive dataset shows comparable haplotype diversity in Central, North and Western Europe, and significantly lower haplotype diversity in the East. All haplotypes observed in the East can be found in the other regions, and haplotype diversity is highest in the Central and Western region. Moreover, there is strong isolation by distance in Central and Western Europe, and only very little in the East. Furthermore, the number of unique haplotypes was highest in France. This pattern strongly suggests that A. vulgaris has originated from a region spanning from France to Western Germany; hence, the slug is probably alien/invasive in other parts of Europe, where it occurs. Our results indicate the necessity to cover as much of the distribution range of a species as possible before making conclusive assumptions about its origin and alien status.

Distinct pathways for zinc metabolism in the terrestrial slug Arion vulgaris

In most organisms, the concentration of free Zn2+ is controlled by metallothioneins (MTs). In contrast, no significant proportions of Zn2+ are bound to MTs in the slug, Arion vulgaris. Instead, this species possesses cytoplasmic low-molecular-weight Zn2+ (LMW Zn) binding compound that divert these metal ions into pathways uncoupled from MT metabolism. Zn2+ is accumulated in the midgut gland calcium cells of Arion vulgaris, where they associate with a low-molecular-weight ligand with an apparent molecular mass of ~ 2,000 Da. Mass spectrometry of the semi-purified LMW Zn binding compound combining an electrospray ion source with a differential mobility analyser coupled to a time-of-flight mass spectrometer revealed the presence of four Zn2+-containing ion signals, which arise from disintegration of one higher MW complex resulting in an ion-mobility diameter of 1.62 nm and a molecular mass of 837 Da. We expect that the novel Zn2+ ion storage pathway may be shared by many other gastropods, and particularly species that possess Cd-selective MT isoforms or variants with only very low affinity to Zn2+.

Occurrence of canine and feline lungworms in Arion vulgaris in a park of Vienna: First report of autochthonous Angiostrongylus vasorum, Aelurostrongylus abstrusus and Troglostrongylus brevior in Austria.

So far, neither the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus brevior nor the canine lungworm Angiostrongylus vasorum was reported in wildlife or intermediate hosts from Austria. The slug Arion vulgaris represents an invasive species in Europe and serves as intermediate host for several lungworm species. This study aimed to analyse the occurrence of metastrongyloid lungworm larvae in slugs in Vienna, Austria. Therefore, 193 A. vulgaris were collected in the central Prater park in summer 2016. Specimens were artificially digested, analysed microscopically for lungworm larvae, and species were confirmed via PCR and sequencing. Out of 193, five slugs were positive to lungworms (2.6%), one for A. vasorum, two for A. abstrusus (genotypes A and B) and one for T. brevior, and one slug had a mixed infection of A. abstrusus and T. brevior larvae. The current study is the first evidence on the endemicity of these metastrongyloid lungworm species in Austria.

The effects of selenium biofortification on mercury bioavailability and toxicity in the lettuce-slug food chain

The effects of foliar Se biofortification (Se+) of the lettuce on the transfer and toxicity of Hg from soil contaminated with HgCl2 (H) and soil collected near the former Hg smelter in Idrija (I), to terrestrial food chain are explored, with Spanish slug as a primary consumer. Foliar application of Se significantly increased Se content in the lettuce, with no detected toxic effects. Mercury exerted toxic effects on plants, decreasing plant biomass, photochemical efficiency of the photosystem II (Fv/Fm) and the total chlorophyll content. Selenium biofortification (Se+ test group) had no effect on Hg bioaccumulation in plants. In slugs, different responses were observed in H and I groups; the I/Se+ subgroup was the most strongly affected by Hg toxicity, exhibiting lower biomass, feeding and growth rate and a higher hepatopancreas/ muscle Hg translocation, pointing to a higher Hg mobility in comparison to H group. Selenium increased Hg bioavailability for slugs, but with opposite physiological responses: alleviating stress in H/Se+ and inducing it in I/Se+ group, indicating different mechanisms of Hg-Se interactions in the food chain under HgCl2 and Idrija soil exposures that can be mainly attributed to different Hg speciation and ligand environment in the soil.

Bionomics of the slug-parasitic nematode Alloionema appendiculatum and its effect on the invasive pest slug Arion vulgaris

Alloionema appendiculatum Schneider, 1859 (Rhabditida: Alloionematidae) is a common parasite of terrestrial molluscs capable of causing high snail mortality in heliculture. It has also been described as a parasite of the invasive slug Arion vulgaris Moquin-Tandon, 1855 (Pulmonata: Arionidae), a serious pest in central Europe. Nontheless, our knowledge about the ecology of this nematode is poor. Our study aims to provide new information about some as yet unknown aspects of the biology of this species, mainly its prevalence, attraction to slug associated cues, development, progeny production, and influence on the mortality and feeding activity of its host. The results of our study provide new information about the saprobic life cycle and natural prevalence of the species, but also show that, in standard conditions, A. appendiculatum has a very weak influence on the mortality and feeding activity of A. vulgaris. We concede that the effect of A. appendiculatum on the slug host can be strongly influenced by bacterial associates, even though the role of bacteria in nematode development is questionable and needs further research. Based on our results, A. appendiculatum does not seem to be a suitable agent for the biocontrol of A. vulgaris.

Comment (Case 3685) – Arion vulgaris Moquin-Tandon, 1855 (Gastropoda, Stylommatophora, Arionidae): support for the modified proposal to preserve the specific name in its accustomed sense

Comment (Case 3685) – Arion vulgaris Moquin-Tandon, 1855 (Gastropoda, Stylommatophora, Arionidae): support for the modified proposal to preserve the specific name in its accustomed sense

Efficacy of chemical and biological slug control measures in response to watering and earthworms

The Spanish Slug (Arion vulgaris, formerly known as Arion lusitanicus) is an invasive agricultural and horticultural pest species that causes great damages all over Europe. Numerous options to control this slug are on the market; among the most commonly used are slug pellets containing the active ingredients metaldehyde or iron-III-phosphate and the application of parasitic nematodes (Phasmarhabditis hermaphrodita). These control measures potentially also affect non-target organisms like earthworms (Lumbricidae), which themselves can directly and/or indirectly alter a plant’s susceptibility against slug herbivory. Also, the efficacy of slug control treatments is expected to be influenced by watering. In a greenhouse experiment we investigated the influence of daily watering vs. every third day watering on slug control efficacy and potential interactions with earthworms. We found significant interactions between watering and slug control efficacy. Slug herbivory and biomass decreased after application of slug pellets; metaldehyde was more effective under less frequent watering while iron-III-phosphate was unaffected by watering. Parasitic nematodes had no effect on slug herbivory and biomass production. Earthworm activity was reduced with less frequent watering but did not interact with slug control. We conclude that watering patterns should be considered when choosing slug control measures.

Měkkýši přírodní rezervace Oheb v Železných horách (východní Čechy) [Molluscs of the Oheb Nature Reserve in the Železné hory Mts. (Eastern Bohemia)

The castle ruin of the Oheb is located above the Seč reservoir in the hilly part of Eastern Bohemia (Czech Republic). The mollusc inventory of this favourable site has already started in the first half of the 20th century (Culek 1944) and has been continuing over the last 50 years (Brabenec 1971, Juřičková 1999). Therefore, the Oheb represents one of the best explored sites in the Czech Republic. The last survey was conducted during the summer 2018 by hand picking and litter sampling at several selected stations. In total, 57 terrestrial mollusc species were recorded during the period 1944–2018. This unusually high species richness is unique, considering relatively poor mollusc fauna of the surrounding area, and represents a classical example of the so-called castle phenomenon. Alinda biplicata, Aegopinella pura, Arianta arbustorum, Helicigona lapicida, Monachoides incarnatus, and Ruthenica filograna were the most frequently recorded species. Arion vulgaris, Oxychilus cellarius, Nesovitrea hammonis, and Malacolimax tenellus have been recorded for the first in 2018 and likely represent modern colonization of the site.

Comment (Case 3685) – Arion vulgaris Moquin-Tandon, 1855 (Gastropoda, Stylommatophora, Arionidae): modified proposal to preserve the specific name in its accustomed sense

Comment (Case 3685) – Arion vulgaris Moquin-Tandon, 1855 (Gastropoda, Stylommatophora, Arionidae): modified proposal to preserve the specific name in its accustomed sense

Fast Recent Expansion of the Spanish Slug (Gastropoda, Stylommatophora, Arionidae) Across Ukraine

Abstract The Spanish slug, a species that is considered to be the most destructive pest among molluscs of Europe, is reported to spread widely across Ukraine during last 5–7 years. In addition to its 5 known colonies in Western Ukraine, over 60 new localities from Western, Central, Northern, Southern and Eastern Ukraine are reported for the first time using own materials and reports with photo from the general public. Newly reported localities include such major cities as Kyiv, Kharkiv, Donetsk, Khmelnitsky, Vinnytsia, Ternopil, Zhytomyr, Lutsk, Chernivtsi and Ivano-Frankivsk, and also the settlements in Odesa and Mykolaiv Regions. Species is also reported for the first time from Grodno City in Belarus and from Moscow City in Russia. Much wider future expansion of the Spanish slug in Eastern Europe is expected in near time.

Molecular detection and quantification of slug parasitic nematodes from the soil and their hosts.

Terrestrial gastropod molluscs are widely distributed and are well known as pests of many types of plants that are notoriously difficult to control. Many species of nematodes are able to parasitize land snails and slugs, but few of them are lethal to their host. Species and/or populations of mollusc-parasitic nematodes (MPNs) that kill their hosts are promising for biological control purposes. The recent discovery of new nematode species of the genus Phasmarhabditis in Europe and the associations between Alloionema spp. and slugs are expanding the possibilities of using MPNs as control agents. However, very little is known about the distribution and ecology of these species. Using molecular techniques based on qPCR methods for quick identification and quantification of various species of MPN isolated directly from the soil or from infected hosts can assist in providing information on their presence and persistence, as well as the composition of natural assemblages. Here, we developed new primers and probes for five species of the genus Phasmarhabditis and one species of the genus Alloionema. We employed these novel molecular techniques and implemented a published molecular set to detect MPN presence in soil samples coming from natural and agricultural areas in Switzerland. We also developed a method that allows the detection and quantification of Phasmarhabditis hermaphrodita directly from the tissues of their slug host in a laboratory experiment. The new molecular approaches were optimized to a satisfactory limit of detection of the species, with only few cross-amplifications with closely related species in late cycles (>32). Using these tools, we detected MPNs in 7.5% of sampled sites, corresponding to forest areas (P. hermaphrodita and Alloionema appendiculatum) and wheat-oriented agricultural areas (Phasmarhabditis bohemica). Moreover, we confirmed that the method can be used to detect the presence of P. hermaphrodita inside slug hosts, with more detections in the susceptible slug Deroceras larvae compared to the resistant Arion vulgaris. These primers/probe sets provide a novel and quick tool to identify MPNs from soil samples and infected slugs without having to culture and retrieve all nematode life stages, as well as a new tool to unravel the ecology of nematode-slug complexes.

Hemocyanin genes as indicators of habitat shifts in Panpulmonata?

Hemocyanin is the primary respiratory protein for the majority of the Mollusca and therefore directly interfaces with the physiological requirements of each species and the environments to which they are adapted. Hemocyanin is therefore likely to have been evolutionarily imprinted by significant habitat shifts. In the gastropod clade Panpulmonata (>30,000 species) major realm transitions have occurred multiple times independently and may have contributed to the diversification of this group. Yet, little is known about the adaptive changes linked to these habitat shifts. In order to gain deeper insight into the evolution of panpulmonate hemocyanins and to infer possible impacts associated with those scenarios, we have assembled and analysed hemocyanin isoforms from 4 panpulmonate species: (i) Helix pomatia, (ii) Cantareus aspersus (both Helicidae, Stylommatophora), (iii) Arion vulgaris (Arionidae, Stylommatophora) and (iv) Lymnaea stagnalis (Lymnaeidae, Hygrophila). Additionally, we describe a new hemocyanin isoform within the genome of the euopisthobranch Aplysia californica. Using these newly acquired hemocyanin data, we performed a phylogenetic analysis that reveals independent duplication events of hemocyanin within lineages that correlate with significant habitat shifts.

Different herbivore responses to two co-occurring chemotypes of the wild crucifer Barbarea vulgaris

According to coevolution theory, plant chemical defences are continually evolving in response to selection by herbivores. Unique to the Brassicales, a few species in the Barbarea genus produce triterpenoid saponins that are highly deterrent to some specialist insect herbivores. One species, B. vulgaris, has diverged into two chemotypes, the G- and P-type, of which the P-type seems to have lost the saponin-based insect resistance by producing different saponin structures; it also produces different glucosinolates and other potential defence traits. Here, we examined the preference and performance of a larger set of specialist and generalist herbivores on the two plant types, including three generalist mollusc (Arion vulgaris, Deroceras sp., Cepaea sp.) as well as three specialist (Phaedon cochleariae, Athalia rosae, Pieris napi oleraceae) and two generalist (Mamestra brassicae, Myzus persicae) insect herbivores. Five out of six herbivore species preferred leaves of the P-type for feeding, and most of them also survived and/or grew better on the P-type, or preferred it for oviposition. In contrast, larvae of M. brassicae showed no preference and performed equally well on the two plant types; the leaf beetle P. cochleariae preferred the G-type for oviposition, which was, however, not reflecting larval performance. Overall, the defences of the P-type against herbivores seem not to be as effective as those of the G-type, which is surprising given its large geographical distribution, overlapping with that of the G-type in Scandinavia and Finland. This suggests that additional ecological interactions determine the success of the two chemotypes.

Occurrence of the invasive Spanish slug in gardens: can a citizen science approach help deciphering underlying factors?

BackgroundThe Spanish slug (Arion vulgaris, also known as A. lusitanicus) is considered one of the most invasive species in agriculture, horticulture and private gardens all over Europe. Although this slug has been problematic for decades, there is still not much known about its occurrence across private gardens and the underlying meteorological and ecological factors. One reason for this knowledge gap is the limited access of researchers to private gardens. Here we used a citizen science approach to overcome this obstacle and examined whether the occurrence of Arionidae in Austrian gardens was associated with meteorological (air temperature, precipitation, global solar radiation, relative humidity) or ecological factors (plant diversity, earthworm activity). Occurrence of the invasive A. vulgaris versus the similar-looking native A. rufus was compared using a DNA-barcoding approach.ResultsSlugs were collected from 1061 gardens from the dry Pannonian lowland to the wet alpine climate (altitudinal range 742 m). Slug abundance in gardens was best explained and negatively associated with the parameters “sum of the mean air temperature in spring”, “number of frost days in the previous winter” and “mean daily global solar radiation on the day of data collection”. Precipitation, plant diversity and earthworm activity were also related to slug abundance, but positively. Out of our genetic sampling of collected slugs, 92% belonged to A. vulgaris.ConclusionsOur study showed that citizen science (i) is a feasible approach to record species occurrence in restricted areas across a wide geographical range and (ii) could be more widely employed in order to identify underlying environmental factors of species occurrence.

Case 3685 — Arion vulgaris Moquin-Tandon, 1855 (Gastropoda, Stylommatophora, Arionidae): proposed validation of the specific name as available

Abstract. The purpose of this application, under Articles 78.1 and 81.1 of the Code, is to conserve the established usage of the species name Arion vulgaris with the authorship of Moquin-Tandon (1855). This name was very frequently used in the last several years, but was primary published as a synonym of Arion rufus Linnaeus, 1758 and it is not available under Article 11.6 of the Code. To avoid confusion and further disturbance of nomenclature the Commission is requested to validate the availability of this name and its authorship.