Historical biogeography of the land snail Cornu aspersum: a new scenario inferred from haplotype distribution in the Western Mediterranean basin

Activities of antioxidant enzymes and Hsp levels in response to elevated temperature in land snail species with varied latitudinal distribution

Land snails occupy a variety of habitats, with differing temperature and humidity regimes and exhibit a wide span of adaptations, to withstand abiotic condition changes. The present work's aim was to examine the correlation of habitat's thermal adversity in different Mediterranean type habitats with the land snail's antioxidant and heat shock responses. For this purpose, snails of different species from populations along a north-south axis from the islands and mainland of Greece were exposed to elevated temperature and antioxidant enzyme activities, and Hsp70 and Hsp90 levels were determined in their tissues. The ATP, ADP, and AMP levels and the adenylate energy charge (AEC) were also determined. The comparison of protein levels and enzymatic activities across time intervals revealed significant differences for all factors examined. While the gradation pattern over time for a given factor was similar in all populations the absolute values over time differed. Catalase activity and the Hsp90 protein levels had the higher contribution in separating the different species and populations, followed by the activity of glutathione reductase and Hsp70 protein levels which contributed to a lesser degree. In general, populations from the southern part of their distribution in Greece tend to display a faster increase than northern populations in induction levels of all factors examined. Our data seem to be in line with the concept of preparation for oxidative stress (POS) while the changes in the AEC indicate an early preparation to cover the energy demand for the induction and synthesis of antioxidant enzymes and Hsps.

Potential of 3-octanone as a lure and kill agent for control of the Brown Garden Snail

The brown garden snail (Cornu aspersum) is a major agricultural pest, causing damage to a wide range of economically important crops. Withdrawal or restricted use of pollutant molluscicides like metaldehyde has prompted a search for more benign control products. This study investigated the response of snails to 3-octanone; a volatile organic compound (VOCs) produced by the insect pathogenic fungus Metarhizium brunneum. Concentrations of 1 - 1000 ppm of 3-octanone were first assessed in laboratory choice assays to determine behavioural response. Repellent activity was found at 1000 ppm whereas attractance was found for the lower concentrations of 1, 10 and 100 ppm. These three concentrations 3-octanone were carried forward in field evaluations to assess potential for use in "lure and kill" strategies. The highest concentration (100 ppm) was the most attractive to the snails but also the most lethal. Even at the lowest concentration this compound proved toxic making 3-octanone an excellent candidate for the development as a snail attractant and molluscicide.

Biogeographic and demographic history of the Mediterranean snakes Malpolon monspessulanus and Hemorrhois hippocrepis across the Strait of Gibraltar

BACKGROUND

The contribution of North Africa to the assembly of biodiversity within the Western Palaearctic is still poorly documented. Since the Miocene, multiple biotic exchanges occurred across the Strait of Gibraltar, underlying the high biogeographic affinity between the western European and African sides of the Mediterranean basin. We investigated the biogeographic and demographic dynamics of two large Mediterranean-adapted snakes across the Strait and assess their relevance to the origin and diversity patterns of current European and North African populations.

RESULTS

We inferred phylogeographic patterns and demographic history of M. monspessulanus and H. hippocrepis, based on range-wide multilocus data, combined with fossil data and species distribution modelling, under present and past bioclimatic envelopes. For both species we identified endemic lineages in the High Atlas Mountains (Morocco) and in eastern Iberia, suggesting their persistence in Europe during the Pleistocene. One lineage is shared between North Africa and southern Iberia and likely spread from the former to the latter during the sea-level low stand of the last glacial stage. During this period M. monspessulanus shows a sudden demographic expansion, associated with increased habitat suitability in North Africa. Lower habitat suitability is predicted for both species during interglacial stages, with suitable areas restricted to coastal and mountain ranges of Iberia and Morocco. Compiled fossil data for M. monspessulanus show a continuous fossil record in Iberia at least since the Pliocene and throughout the Pleistocene.

CONCLUSIONS

The previously proposed hypothesis of Pleistocene glacial extinction of both species in Europe is not supported based on genetic data, bioclimatic envelopes models, and the available fossil record. A model of range retraction to mountain refugia during arid periods and of glacial expansion (demographic and spatial) associated to an increase of Mediterranean habitats during glacial epochs emerges as a general pattern for mesic vertebrates in North Africa. Moreover, the phylogeographic pattern of H. hippocrepis conforms to a well-established biogeographic partition between western and eastern Maghreb.

Incorporating palaeogeography into ancestral area estimation can explain the disjunct distribution of land snails in Macaronesia and the Balearic Islands (Helicidae: Allognathini)

The systematics and biogeographical history of the Eastern Mediterranean and Macaronesian land snail tribe Allognathini (Helicidae: Helicinae) is investigated based on mitochondrial and nuclear DNA sequence data. Our molecular phylogenetic analyses indicate that the genus-group systematics of the tribe needs to be revised. We show for the first time that the narrow-range endemics Lampadia and Idiomela from the Madeira Archipelago belong to Allognathini and represent together the sister group of the diverse Canary Island Hemicycla radiation. We therefore suggest synonymising Lampadiini with Allognathini. Sister to these Macaronesian genera was the Balearic Island Allognathus radiation. Pseudotachea was not recovered as a monophyletic group and the two currently recognised species clustered in Iberus. Similarly, Adiverticula was not recovered as a monophyletic group and clustered in Hemicycla. We therefore suggest synonymising Pseudotachea with Iberus and Adiverticula with Hemicycla. The six genera in Allognathini, which we distinguish here (Cepaea, Iberus, Allognathus, Hemicycla, Idiomela and Lampadia), originated in Western to South-western Europe according to our ancestral area estimation and the fossil record. The disjunct distribution of the Balearic Islands and Macaronesian sister clades and the mainly Iberian Iberus clade that separated earlier can be explained by the separation of the Betic-Rif System from the Iberian Peninsula during the late Oligocene to early Miocene, along with independent Miocene dispersals to the Balearic Islands and Macaronesia from the Iberian Peninsula, where the ancestral lineage became extinct.

Deep genetic structure at a small spatial scale in the endangered land snail Xerocrassa montserratensis

Species with small geographic ranges do not tend to have a high genetic structure, but some land snail species seem to be an exception. Xerocrassa montserratensis, an endangered land snail endemic to Catalonia (northeastern Iberian Peninsula), is an excellent model to study the processes affecting the phylogeography of specialized species of conservation concern. This species is restricted to xerophilous stony slopes and occurs within a small and fragmented area of ca. 500 km2. We sequenced the COI barcode region of 152 individuals from eight sites covering the entire range of the species. We found four genetic groups mostly coincident with their geographic distribution: a central ancestral group containing shared haplotypes among five localities and three groups restricted to a single locality each. Two of these derived groups were geographically and genetically isolated, while the third and most differentiated group was not geographically isolated. Geomorphologic and paleoclimatic processes during the Pleistocene can explain the divergence found between populations of this low dispersal species with historical fragmentation and secondary contacts. Nonetheless, recent passive large dispersal through streams was also detected in the central group. Overall, our study uncovered four evolutionary units, partially matching morphologically described subspecies, which should be considered in future conservation actions.

Climatic oscillations during the Mio/Pliocene epochs induced cladogenesis in the terrestrial snail genus Gittenedouardia (Mollusca: Gastropoda: Cerastidae) from South Africa

In South Africa, the terrestrial snail genus Gittenedouardia is the most species-rich member of the Cerastidae, where it is primarily distributed in the highly fragmented Afrotemperate and Indian Ocean coastal belt (IOCB) forest biomes. Phylogenetic relationships and cladogenetic events within the genus remain unstudied. In this respect, we reconstructed a dated phylogeny for eight Gittenedouardia species, and two populations identified to genus level using a combined mitochondrial (16S rRNA and COI) DNA sequencing dataset analysed using Bayesian inference and Maximum Likelihood framework. Furthermore, we investigated the population genetic substructure of the three widely distributed species (Gittenedouardia spadicea, G. natalensis and G. arenicola) for the COI locus, while also subsampling these species using the nuclear DNA ITS-2 locus. Phylogenetic results based on the combined mtDNA dataset supported the monophyly of Gittenedouardia and revealed three major clades and deep genetic structure among the three widely distributed species. Divergence-time estimates suggest that diversification within Gittenedouardia occurred during the middle Miocene/late Pliocene, a period characterised by a decrease in precipitation and the contraction of the Afrotemperate and IOCB forest biomes. We used two species delimitation methods, (PTP and STACEY) to infer putative species in G. spadicea, G. natalensis and G. arenicola. The two methods recovered a large number of evolutionary distinct units, with minimal consensus in the exact number of lineages. Our findings suggest the presence of undescribed diversity, necessitating the need for taxonomic revisionary work on Gittenedouardia. We discuss the climatic factors which may have contributed to the observed cladogenesis and compare our results with other studies of forest dwelling faunal taxa.

The effect of landscape on functional connectivity and shell shape in the land snail Humboldtiana durangoensis

The populations of Humboldtiana durangoensis have experienced a drastic reduction in the effective population size; in addition, the species is threatened by anthropogenic activities. For the aforementioned, landscape genetics will serve as a tool to define the potential evolutionarily significant units (ESU) for this species. To complete our objective, we evaluated the effect of cover vegetation and climate on the functional connectivity of the species from the last glacial maximum (LGM) to the present as well as the effect of climate on shell shape. Partial Mantel tests, distance-based redundance analysis and a Bayesian framework were used to evaluate connectivity. On the other hand, geometric morphometrics, phylogenetic principal component analysis and redundancy analysis were used for the analysis of shell shape. Our results suggest that the suitable areas have been decreasing since the LGM; also, vegetation cover rather than climate has influenced the genetic connectivity among land snail populations, although temperature had a high influence on shell shape in this species. In conclusion, vegetation cover was the main factor that determined the functional connectivity for the land snail; however, local selective pressures led to different phenotypes in shell shape that allowed us to postulate that each one of the previously defined genetic groups must be considered as a different ESU.

Brachylaima spp. (Trematoda) parasitizing Cornu aspersum (Gastropoda) in France with potential risk of human consumption

The edible land snail Cornu aspersum, native to the Mediterranean coastlines of North Africa, is widely distributed on most continents and often invasive in areas where introduction is recent. This species could contribute to the geographic spread of parasites as demonstrated for Brachylaima spp. These cosmopolitan trematodes may represent a threat to human health, like in Australia where Brachylaima cribbi infects humans. In this study, we demonstrate for the first time the occurrence of Brachylaima spp. in two French populations of C. aspersum, Thorigné-Fouillard (Ille-et-Vilaine), and Arçais (Deux-Sèvres), with an overall prevalence of 10.4% (Thorigné-Fouillard) and 73.3% (Arçais), respectively and a metacercarial intensity on average three times higher in Thorigné-Fouillard (37) than in Arçais (11). Cornu aspersum may act as a first and second intermediate host, as demonstrated in Arçais. The morphometrics of metacercariae, particularly the great body length about 2 mm, discriminate our Brachylaima species from those already described in C. aspersum (B. cribbi in Australia, and B. aspersae, B. llobregatensis and B. mascomai in Europe). Molecular analysis, based on 28S and COI, suggests the occurrence of two species in our study, one of which is probably Brachylaima mesostoma, an intestinal parasite of passeriform birds described in Central Europe. We underline the need for further research to identify species of Brachylaima in France and measure the health hazard of consuming field-collected snails.

Evolutionary history of two cryptic species of northern African jerboas

BACKGROUND

Climatic variation and geologic change both play significant roles in shaping species distributions, thus affecting their evolutionary history. In Sahara-Sahel, climatic oscillations shifted the desert extent during the Pliocene-Pleistocene interval, triggering the diversification of several species. Here, we investigated how these biogeographical and ecological events have shaped patterns of genetic diversity and divergence in African Jerboas, desert specialist rodents. We focused on two sister and cryptic species, Jaculus jaculus and J. hirtipes, where we (1) evaluated their genetic differentiation, (2) reconstructed their evolutionary and demographic history; (3) tested the level of gene flow between them, and (4) assessed their ecological niche divergence.

RESULTS

The analyses based on 231 individuals sampled throughout North Africa, 8 sequence fragments (one mitochondrial and seven single copy nuclear DNA, including two candidate genes for fur coloration: MC1R and Agouti), 6 microsatellite markers and ecological modelling revealed: (1) two distinct genetic lineages with overlapping distributions, in agreement with their classification as different species, J. jaculus and J. hirtipes, with (2) low levels of gene flow and strong species divergence, (3) high haplotypic diversity without evident geographic structure within species, and (4) a low level of large-scale ecological divergence between the two taxa, suggesting species micro-habitat specialization.

CONCLUSIONS

Overall, our results suggest a speciation event that occurred during the Pliocene-Pleistocene transition. The contemporary distribution of genetic variation suggests ongoing population expansions. Despite the largely overlapping distributions at a macrogeographic scale, our genetic results suggest that the two species remain reproductively isolated, as only negligible levels of gene flow were observed. The overlapping ecological preferences at a macro-geographic scale and the ecological divergence at the micro-habitat scale suggest that local adaptation may have played a crucial role in the speciation process of these species.

Population genetic structure of the land snail Camaena cicatricosa (Stylommatophora, Camaenidae) in China inferred from mitochondrial genes and ITS2 sequences

The phylogeographic structure of the land snail Camaena cicatricosa was analyzed in this study based on mitochondrial gene (COI and 16srRNA, mt DNA) and internal transcribed spacer (ITS2) sequences in 347 individuals. This snail is the vector of the zoonotic food-borne parasite Angiostrongylus cantonensis and one of the main harmful snails distributed exclusively in China. The results revealed significant fixation indices of genetic differentiation and high gene flow between most populations except several populations. An isolation-by-distance test showed no significant correlation between genetic distance and geographical distance among C. cicatricosa populations, which suggested that gene flow was not restricted by distance. The levels of haplotype and nucleotide diversity of C. cicatricosa were generally high, except those in some special populations, according to the mt DNA and ITS2 data. Furthermore, the phylogenetic trees and asteroid networks of haplotypes indicated nonobvious genetic structure, the same as results got based on the synonymous and non synonymous sites of 347 sequences of the COI gene. All lines of evidence indicated that climatic changes and geographical and human barriers do not substantially affect the current population structure and distribution of the investigated snails.

The transcriptome of a "sleeping" invader: de novo assembly and annotation of the transcriptome of aestivating Cornu aspersum

Background

Cornu aspersum is a quite intriguing species from the point of view of ecology and evolution and its potential use in medical and environmental applications. It is a species of economic importance since it is farmed and used for culinary purposes. However, the genomic tools that would allow a thorough insight into the ecology, evolution, nutritional and medical properties of this highly adaptable organism, are missing. In this work, using next-generation sequencing (NGS) techniques we assessed a significant portion of the transcriptome of this non-model organism.

Results

Out of the 9445 de novo assembled contigs, 2886 (30.6%) returned significant hits and for 2261 (24%) of them Gene Ontology (GO) terms associated to the hits were retrieved. A high percentage of the contigs (69.4%) produced no BLASTx hits. The GO terms were grouped to reflect biological processes, molecular functions and cellular components. Certain GO terms were dominant in all groups. After scanning the assembled transcriptome for microsatellites (simple sequence repeats, SSRs), a total of 563 SSRs were recovered. Among the identified SSRs, trinucleotide repeats were the predominant followed by tetranucleotide and dinucleotide repeats.

Conclusion

The annotation success of the transcriptome of C. aspersum was relatively low. This is probably due to the very limited number of annotated reference genomes existing for mollusc species, especially terrestrial ones. Several biological processes being active in the aestivating species were revealed through the association of the transcripts to enzymes relating to the pathways. The genomic tools provided herein will eventually aid in the study of the global genomic diversity of the species and the investigation of aspects of the ecology, evolution, behavior, nutritional and medical properties of this highly adaptable organism.

Brachylaimiasis: Brachylaima spp. (Digenea: Brachylaimidae) Metacercariae Parasitizing the Edible Snail Cornu aspersum (Helicidae) in Spanish Public Marketplaces and Health-Associated Risk Factors

The edible land snail Cornu aspersum (Pulmonata: Stylommatophora) acts as a second intermediate host in the terrestrial life cycle of Brachylaima spp. trematodes, harboring unencysted metacercariae in its kidney. The ingestion of undercooked infected snails by humans may allow metacercariae to potentially develop to adult stage in the intestine, causing brachylaimiasis, as already seen in Australia. The prevalence and dynamics of C. aspersum parasitization by Brachylaima spp. metacercariae in specimens intended for human consumption in Spanish marketplaces were studied. In total, 3,710 C. aspersum specimens were analyzed over 5 yr, which were obtained from public marketplaces in the Spanish cities of Barcelona, Bilbao, Madrid, Tudela, Valencia, and Zaragoza. The overall prevalence was 41.97% (95% CI: 40.38-45.56%). The Tudela marketplace had the highest values for both the seasonal prevalence and abundance in all studies during autumn (93.57% and 3.09, respectively). This market also gave the highest individual metacercarial burden recorded, 212 metacercariae in a single specimen. Overall, the highest prevalence of Brachylaima spp. occurred in autumn (58.65%) and the lowest in winter (22.64%). There was a seasonal effect on prevalence, which increased from summer to autumn and then decreased in winter. In total, 96 experimental Brachylaima adults were obtained from the metacercariae parasitizing the analyzed snails. These were identified through morphometric tools (principal component analysis) as Brachylaima mascomai (56 in Barcelona, 1 in Bilbao, 7 in Tudela, and 3 in Valencia), and Brachylaima llobregatensis (17 in Barcelona, 8 in Bilbao, 1 in Valencia, and 3 in Zaragoza). Logistic regression modeling, conducted to predict the probability of purchasing parasitized snails using city and season as predictors showed a correct prediction overall of 79.0%, with a significant (p = 0.001) risk effect in the Barcelona-autumn interaction (2.551-38.442), a significant (p = 0.049) protection effect in the Tudela-spring interaction (0.076-0.997), a significant (p < 0.001) risk effect in the Tudela-autumn interaction (4.330-78.584), and a significant (p = 0.014) protection effect in the Valencia-spring interaction (0.033-0.687). The high overall prevalence of Brachylaima spp. metacercariae should be a matter of concern for public health authorities, mainly in countries where C. aspersum is consumed.

Laboratory studies on the thermal tolerance and response of enzymes of intermediate metabolism in different land snail species

Land snails species occur in a range of habitats from humid to semi-arid and arid ones and seasonal variations in their physiology and biochemical composition have been linked to annual cycles of photoperiod, temperature, humidity and water availability. In an effort to understand the thermal tolerance and the impact of temperature elevation on tissue metabolism of land snails we determined the mortality, heamolymph PO₂ and the activities of enzymes of intermediary metabolism in three land snail species (Helix lucorum, Helix pomatia and Cornu aspersum) differing in their geographical distribution and inhabiting areas with different climatic characteristics. No mortality was observed in both population of Cornu aspersum, while Helix pomatia exhibited higher mortality than Helix lucorum. PO₂ dropped within the first 10days of exposure to elevated temperature in all species, although in Cornu aspersum this decrease was significantly lower. No significant reduction in the enzymatic activities of all glycolytic enzymes studied, as well as of citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HOAD) was observed in the more thermal tolerant species C. aspersum from both populations studied. Significant reductions of enzymatic activity of the glycolytic enzymes phosphofructokinase (PFK), pyruvate kinase (PK) and d-Lactate dehydrogenase (d-LDH) was observed in Helix lucorum and Helix pomatia. The observed inter-specific differences seem to be in accordance with the life cycle characteristics of each species and may be attributed to climatic differences among habitats within their distribution range.

Historical Biogeography of the Marine Snail Littorina saxatilis Inferred from Haplotype and Shell Morphology Evolution in NW Spain

The marine snail Littorina saxatilis exhibits extreme morphological variation between and within geographical regions and represents an excellent model for assessing local adaptation. Previous studies support the hypothesis of parallel evolution in sympatry of two morphologically different ecotypes (named as RB and SU) that co-inhabit different habitats from Galician rocky shores (NW Spain), and which are interrupted by sheltered areas inhabited by a different morph never studied before (named as SRB). Here, we use morphological and mitochondrial DNA (mtDNA) sequence data to test hypotheses on the origin and diversification of SRB snails and to assess their evolutionary relationships with RB and SU ecotypes. Our results show that the SRB morph displays the largest size and shell elongation and the smallest relative shell aperture, representing an extreme type of the RB vs. SU polymorphism, which has been linked to adaptation to sheltered ecological factors. Phylogenetic analysis shows that the SRB morph shares ancestry with RB and SU ecotypes, rejecting the hypothesis that the SRB morph marks relict populations from which these ecotypes evolved in Galician coasts. Our data support that genetic differentiation among SRB, RB and SU morphs results from a general pattern of restricted gene flow and isolation by distance linked to the colonization of Galician coasts by two independent mtDNA lineages, rather than from a random fragmentation of the initial distributional range. Therefore, the confinement of distinct lineages to specific geographical areas denote evident limits to the distances these snails can disperse. Morphological analysis indicates no association between mtDNA lineage and a specific morphotype, and suggests the independent gain of convergent morphological patterns within each mtDNA lineage in populations occupying contrasting habitats following the colonization of Galician coasts.

Genetic differentiation of the pine processionary moth at the southern edge of its range: contrasting patterns between mitochondrial and nuclear markers

The pine processionary moth (Thaumetopoea pityocampa) is an important pest of coniferous forests at the southern edge of its range in Maghreb. Based on mitochondrial markers, a strong genetic differentiation was previously found in this species between western (pityocampa clade) and eastern Maghreb populations (ENA clade), with the contact zone between the clades located in Algeria. We focused on the moth range in Algeria, using both mitochondrial (a 648 bp fragment of the tRNA-cox2) and nuclear (11 microsatellite loci) markers. A further analysis using a shorter mtDNA fragment and the same microsatellite loci was carried out on a transect in the contact zone between the mitochondrial clades. Mitochondrial diversity showed a strong geographical structure and a well-defined contact zone between the two clades. In particular, in the pityocampa clade, two inner subclades were found whereas ENA did not show any further structure. Microsatellite analysis outlined a different pattern of differentiation, with two main groups not overlapping with the mitochondrial clades. The inconsistency between mitochondrial and nuclear markers is probably explained by sex-biased dispersal and recent afforestation efforts that have bridged isolated populations.

Revision of sinistral land snails of the genus Camaena (Stylommatophora, Camaenidae) from China based on morphological and molecular data, with description of a new species from Guangxi, China

The camaenid land snail genus Camaena is widely distributed throughout Southeast Asia. Thirteen species are found in China alone. Among these, Camaena cicatricosa (Müller, 1774) is the most widely distributed species, including four subspecies, Camaena cicatricosa ducalis (Ancey, 1885), Camaena cicatricosa inflata (Möllendorff, 1885), Camaena cicatricosa obtecta (Fischer, 1898) and Camaena cicatricosa connectens (Dautzenberg & Fischer, 1906). The systematics of these taxa is revised herein based on comparative shell morphology and anatomy as well as analyses of DNA sequences of two mitochondrial genes (COI, 16S rRNA) and one nuclear marker, ITS2. We found that all subspecies form well-supported clades in a molecular phylogeny and are well-differentiated from each other by genetic distances that are consistent with amounts of interspecific differentiation. In addition, they clearly differ from each other in reproductive features. Based on these observations, we elevate all four subspecies to the rank of full species. Moreover, based on morphological and mitochdondrial differentiation, we describe a new species, Camaena poyuensis sp. n. from Guangxi, China. The new species conspicuously differs from its sibling species Camaena cicatricosa in having a larger and more depressed shell, a completely covered umbilicus, more or less purplish peristome, an obtuse angle at the junction of the basal and columellar lip, longer pedunculus of the bursa copulatrix, thicker epiphallus and penis, and short conic verge. Previous named species are also redescribed on their shell and anatomical characters, because the original descriptions are uninformative.

Felid Lungworms and Heartworms in Italy: More Questions than Answers?

Nematodes infecting the cardiorespiratory system of cats have recently stimulated high scientific interest. Over the past few years, different aspects of these parasites have been clarified and various issues elucidated. This increased knowledge has improved awareness on this topic but, at the same time, some dilemmas have not been solved and new questions have been raised. In this review, we underline and discuss current knowledge of, and new doubts relating to, feline lungworms and heartworms, with the aim of stimulating new studies to fill gaps of basic (i.e., epidemiology and biology) and applied (i.e., clinical aspects) knowledge of the old and new parasites affecting the cardiorespiratory system of cats.

Praziquantel efficacy against Brachylaima sp. metacercariae (Trematoda: Brachylaimidae) parasitizing the edible landsnail Cornu aspersum and its HPLC-MS/MS residue determination

Cornu aspersum is a terrestrial edible snail, often parasitized by Brachylaima (Trematoda) metacercariae. Ingestion of undercooked snails by humans allows metacercariae to develop to adult in the intestine causing brachylaimiasis (expected mortality rate 5-10%). The cosmopolitan character of the trematode and of its vector, enhanced in a future climate change scenario, and the absence of adequate sanitary controls of the snails in marketplaces clearly increase the risk of human brachylaimiasis. The treatment of farmed snails with praziquatel (PZQ) would be a tool to control this food-borne disease. The objectives of this study were: to report the prevalence of Brachylaima metacercariae parasitizing C. aspersum in marketplaces, to assess the efficacy and tolerance of PZQ in C. aspersum and to develop an HPLC-MS/MS analytical method to quantify PZQ residue in the edible snail (the acceptable daily intake of PZQ is 0.17 mg/kg bw in humans). Prevalence of parasitization of C. aspersum by Brachylaima metacercariae in public marketplaces reached the 80%. PZQ was orally administered to snails, mixed with the usual snail food. In dose determination assays three doses were individually tested (10 days): 1.2 mg PZQ/snail, 1.8 mg PZQ/snail (efficacy 97.3%, p < 0.001) and 2.4 mg PZQ/snail (efficacy 98.7%, p < 0.001). In dose confirmation tests (n = 200) the 2.4 mg PZQ/snail dose was group tested (10 snails/box, 7 days): 2 g of PZQ supplemented snail food were disposed daily in the treatment group boxes and 2 g of snail food (placebo) in the control boxes (efficacy 94.6%, p < 0.001; prevalence dropped from 68.7% in control group to 10.1% in treatment group, p < 0.001). Received dose was 220.2 mg PZQ/kg snail with shell. In the analytical method, linearity, lower limit of quantification (0.05 μg/ml), selectivity, carry over, accuracy, precision, dilution integrity, matrix effect and stability were tested. Sixty snails were treated (11 mg PZQ/g snail food) and analyzed. PZQ was detected and quantified (0.093 mg PZQ/g snail). PZQ treatment of C. aspersum is effective, well tolerated by the snail, affordable and easy to reproduce in snail farms.

Metastrongyloid infection by Aelurostrongylus abstrusus, Troglostrongylus brevior and Angiostrongylus chabaudi in a domestic cat

The "cat lungworm", Aelurostrongylus abstrusus, affects cats worldwide. Recently, other cardio-pulmonary parasites, e.g. Troglostrongylus brevior and Angiostrongylus chabaudi, have been isolated from cats either for the first time or a long time after they were first described. This paper describes the first known mixed infection by A. abstrusus, T. brevior and A. chabaudi in a domestic cat. Biological and epidemiological implications of old and "new" metastrongyloid-caused infections in cats are discussed.

Canine angiostrongylosis: recent advances in diagnosis, prevention, and treatment

Angiostrongylus vasorum is a parasitic nematode affecting the heart and pulmonary arteries of wild (eg, foxes) and domestic canids. The parasite has an indirect life cycle in which slugs and snails act as intermediate hosts. In the last few years the parasite has spread outside the traditional endemic foci, and there is a rise of documented cases of canine angiostrongylosis across Europe. Angiostrongylus vasorum causes cardiopulmonary disorders and coagulopathies, along with different nonspecific clinical signs. Fatal infections are frequently reported. Given the severity of the infection and the recent geographic spreading of the parasite, this article reviews and discusses the current knowledge of A. vasorum, with a special focus on recent insights on diagnosis, prevention, and treatment of dog angiostrongylosis.

Phylogeography of the land snail genus Orcula (Orculidae, Stylommatophora) with emphasis on the Eastern Alpine taxa: speciation, hybridization and morphological variation

BACKGROUND

The Central and Southern European mountain ranges represent important biodiversity hotspots and show high levels of endemism. In the land snail genus Orcula Held, 1837 nine species are distributed in the Alps and a few taxa inhabit the Carpathians, the Dinarids and the Western Black Sea region. In order to elucidate the general patterns of temporal and geographic diversification, mitochondrial and nuclear markers were analyzed in all 13 Orcula species. We particularly aimed to clarify whether the Alpine taxa represent a monophyletic group and if the local species diversity is rather the result of isolation in geographically separated Pleistocene glacial refuges or earlier Tertiary and Quaternary palaeogeographic events. In order to test if patterns of molecular genetic and morphological differentiation were congruent and/or if hybridization had occurred, shell morphometric investigations were performed on the Orcula species endemic to the Alps.

RESULTS

The phylogenetic trees resulting from the analyses of both the mitochondrial (COI, 12S and 16S) and the nuclear (H4/H3) data sets revealed three main groups, which correspond to the three subgenera Orcula, Illyriobanatica and Hausdorfia. The reconstruction of the historic geographic ranges suggested that the genus originated in the Dinarides during the Middle Miocene and first colonized the Alps during the Late Miocene, giving rise to the most diverse subgenus Orcula. Within the latter subgenus (including all Alpine endemics) almost all species were differentiated by both molecular genetic markers and by shell morphometrics, except O. gularis and O. pseudodolium.

CONCLUSIONS

The present study confirms the importance of the Alps as biodiversity hotspot and origin center of land snail diversity. The species diversity in the subgenus Orcula was likely promoted by Miocene to Pliocene palaeogeographic events and the insular distribution of preferred limestone areas. In some cases, speciation events could be linked to the divergence of populations in glacial refuges during the Pleistocene. Sporadic contact between geographically separated and reproductively not yet isolated populations led to intermixture of haplogroups within species and even hybridization and mitochondrial capture between species.

Cardio-Pulmonary Parasitic Nematodes Affecting Cats in Europe: Unraveling the Past, Depicting the Present, and Predicting the Future

Various cardio-pulmonary parasitic nematodes infecting cats have recently been fascinating and stimulating the attention of the Academia, pharmaceutical companies, and veterinary practitioners. This is the case of the metastrongyloids: Aelurostrongylus abstrusus and Troglostrongylus brevior, the trichuroid: Capillaria aerophila (syn. Eucoleus aerophilus), and the filarioid: Dirofilaria immitis. Apparently, these parasites have been emerging in several European countries, thus, gaining an important role in feline parasitology and clinical practice. Under a practical standpoint, a sound knowledge of the biological, epidemiological, and clinical impact of cardio-respiratory parasitoses affecting cats, in addition to a potential risk of introduction, establishment, and spreading of “new” parasites in Europe is mandatory in order to understand the present and future impact for feline medicine and to address new strategies of control and treatment. The purpose of the present article is to review the current knowledge of heartworm and lungworm infections in cats, discussing and comparing past and present issues, and predicting possible future scenarios.

Ecological niche and phylogeography elucidate complex biogeographic patterns in Loxosceles rufescens (Araneae, Sicariidae) in the Mediterranean Basin

BACKGROUND

Understanding the evolutionary history of morphologically cryptic species complexes is difficult, and made even more challenging when geographic distributions have been modified by human-mediated dispersal. This situation is common in the Mediterranean Basin where, aside from the environmental heterogeneity of the region, protracted human presence has obscured the biogeographic processes that shaped current diversity. Loxosceles rufescens (Araneae, Sicariidae) is an ideal example: native to the Mediterranean, the species has dispersed worldwide via cohabitation with humans. A previous study revealed considerable molecular diversity, suggesting cryptic species, but relationships among lineages did not correspond to geographic location.

RESULTS

Delimitation analyses on cytochrome c oxidase subunit I identified 11 different evolutionary lineages, presenting two contrasting phylogeographic patterns: (1) lineages with well-structured populations in Morocco and Iberia, and (2) lineages lacking geographic structure across the Mediterranean Basin. Dating analyses placed main diversification events in the Pleistocene, and multiple Pleistocene refugia, identified using ecological niche modeling (ENM), are compatible with allopatric differentiation of lineages. Human-mediated transportation appears to have complicated the current biogeography of this medically important and synanthropic spider.

CONCLUSIONS

We integrated ecological niche models with phylogeographic analyses to elucidate the evolutionary history of L. rufescens in the Mediterranean Basin, with emphasis on the origins of mtDNA diversity. We found support for the hypothesis that northern Africa was the center of origin for L. rufescens, and that current genetic diversity originated in allopatry, likely promoted by successive glaciations during the Pleistocene. We corroborated the scenario of multiple refugia within the Mediterranean, principally in northern Africa, combining results from eight atmosphere-ocean general circulation models (AOGCMs) with two different refugium-delimitation methodologies. ENM results were useful for providing general views of putative refugia, with fine-scale details depending on the level of stringency applied for agreement among models.

Terrestrial edible land snails as vectors for geographic dissemination of Brachylaima species

Cornu aspersum (= syn. Helix aspersa ) snails imported into NE Spain from Algeria and South Africa, and intended for human consumption via sale in public markets, were analyzed to assess their contribution to geographic dissemination of Brachylaima species. Prevalence and viability studies of metacercariae were performed on Algerian and South African Brachylaima adults. Morphometric studies were performed by measuring 16 variables in metacercariae and 18 variables in adults. Principal component analyses (PCA) were performed to assess the contribution of each variable in the separation of the different groups. A MANOVA test performed on morphometric data from Brachylaima llobregatensis and Brachylaima mascomai Algerian and South African adults, revealed a significant multivariate main effect (P < 0.001) and univariate effects in 13 variables (P ≤ 0.001). Pairwise comparisons revealed significant differences in 13 variables between B. mascomai and Algerian adults, as opposed to 3 variables (testis I width, testis II width, and egg width) when compared with B. llobregatensis. South African adults had significant differences in 5 variables (body length, oral sucker length, oral sucker width, egg length, and egg width) when compared with B. llobregatensis, as opposed to 1 variable (testis II width) when compared with B. mascomai. Results from PCA showed 2 different groups: B. llobregatensis/Algerian adults (overlapped) and B. mascomai/South African adults (overlapped). Imported edible C. aspersum specimens can contribute significantly to the geographic spread of Brachylaima species by harboring infective metacercariae which could easily infect animals, given their heteroxenous character. Brachylaima llobregatensis has previously been detected in NE Spain only, and now this species appears to be parasitizing C. aspersum in Algeria (North Africa). This geographic dispersion could be favored by commerce in terrestrial snails such as C. aspersum.

Development of the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus brevior in Helix aspersa snails

Aelurostrongylus abstrusus (Strongylida, Angiostrongylidae) and Troglostrongylus brevior (Strongylida, Crenosomatidae) are regarded as important lungworm species of domestic felids, with the latter considered an emerging threat in the Mediterranean region. The present study aimed to assess their concurrent development in the mollusc Helix aspersa (Pulmonata, Helicidae). Thirty snails were infested with 100 first-stage larvae (L1) of A. abstrusus and T. brevior, isolated from a naturally infested kitten. Larval development was checked by digesting five specimens at 2, 6 and 11 days post infestation. Larvae retrieved were morphologically described and their identification was confirmed by specific PCR and sequencing. All H. aspersa snails were positive for A. abstrusus and T. brevior, whose larval stages were simultaneously detected at each time point. In addition, snails were exposed to outdoor conditions and examined after overwintering, testing positive up to 120 days post infestation. Data herein presented suggest that A. abstrusus and T. brevior develop in H. aspersa snails and may eventually co-infest cats. Data on the morphology of both parasitic species in H. aspersa provide additional information on their development and identification, to better understand the population dynamics of these lungworms in receptive snails and paratenic hosts.

Variation in thermal sensitivity and thermal tolerances in an invasive species across a climatic gradient: lessons from the land snail Cornu aspersum

The ability of organisms to perform at different temperatures could be described by a continuous nonlinear reaction norm (i.e., thermal performance curve, TPC), in which the phenotypic trait value varies as a function of temperature. Almost any shift in the parameters of this performance curve could highlight the direct effect of temperature on organism fitness, providing a powerful framework for testing thermal adaptation hypotheses. Inter-and intraspecific differences in this performance curve are also reflected in thermal tolerances limits (e.g., critical and lethal limits), influencing the biogeographic patterns of species' distribution. Within this context, here we investigated the intraspecific variation in thermal sensitivities and thermal tolerances in three populations of the invasive snail Cornu aspersum across a geographical gradient, characterized by different climatic conditions. Thus, we examined population differentiation in the TPCs, thermal-coma recovery times, expression of heat-shock proteins and standard metabolic rate (i.e., energetic costs of physiological differentiation). We tested two competing hypotheses regarding thermal adaptation (the "hotter is better" and the generalist-specialist trade-offs). Our results show that the differences in thermal sensitivity among populations of C. aspersum follow a latitudinal pattern, which is likely the result of a combination of thermodynamic constraints ("hotter is better") and thermal adaptations to their local environments (generalist-specialist trade-offs). This finding is also consistent with some thermal tolerance indices such as the Heat-Shock Protein Response and the recovery time from chill-coma. However, mixed responses in the evaluated traits suggest that thermal adaptation in this species is not complete, as we were not able to detect any differences in neither energetic costs of physiological differentiation among populations, nor in the heat-coma recovery.

The complete mitochondrial genome of the land snail Cornu aspersum (Helicidae: Mollusca): intra-specific divergence of protein-coding genes and phylogenetic considerations within Euthyneura

The complete sequences of three mitochondrial genomes from the land snail Cornu aspersum were determined. The mitogenome has a length of 14050 bp, and it encodes 13 protein-coding genes, 22 transfer RNA genes and two ribosomal RNA genes. It also includes nine small intergene spacers, and a large AT-rich intergenic spacer. The intra-specific divergence analysis revealed that COX1 has the lower genetic differentiation, while the most divergent genes were NADH1, NADH3 and NADH4. With the exception of Euhadra herklotsi, the structural comparisons showed the same gene order within the family Helicidae, and nearly identical gene organization to that found in order Pulmonata. Phylogenetic reconstruction recovered Basommatophora as polyphyletic group, whereas Eupulmonata and Pulmonata as paraphyletic groups. Bayesian and Maximum Likelihood analyses showed that C. aspersum is a close relative of Cepaea nemoralis, and with the other Helicidae species form a sister group of Albinaria caerulea, supporting the monophyly of the Stylommatophora clade.

Larval development of the feline lungworm Aelurostrongylus abstrusus in Helix aspersa

The cat lungworm Aelurostrongylus abstrusus affects the domestic cat and other felids all over the world. Feline aelurostrongylosis is of importance in clinical feline medicine and is gaining more and more attention for the present expansion in the geographical range of A. abstrusus. Global warming and changes in phenology of snail intermediate hosts have been incriminated in this spreading. Helix aspersa, a potential vector of A. abstrusus, is endemic in most regions of the world, where it has become recently a pest outside its native Mediterranean range. The present work evaluated key features of larval development of A. abstrusus in H. aspersa at two different temperature conditions. The results showed that A. abstrusus may reach the infective stage in muscular foot and viscera of H. aspersa and that environmental temperatures may influence the biological cycle of the cat lungworm. In particular, the higher the average temperature, the higher the rate of larval development, i.e., about 50% of larvae of A. abstrusus reached the infective stage between temperatures of 18.8-29.5 °C, while only 17.8% of larvae completed their development at temperatures of 6.7-22 °C. Biological and epidemiological implications are discussed.

Exploring species level taxonomy and species delimitation methods in the facultatively self-fertilizing land snail genus Rumina (gastropoda: pulmonata)

Delimiting species in facultatively selfing taxa is a challenging problem of which the terrestrial pulmonate snail genus Rumina is a good example. These snails have a mixed breeding system and show a high degree of shell and color variation. Three nominal species (R. decollata, R. saharica and R. paivae) and two color morphs within R. decollata (dark and light) are currently recognized. The present study aims at evaluating to what extent these entities reflect evolutionary diverging taxonomic units, rather than fixed polymorphisms due to sustained selfing. Therefore, a phylogenetic analysis of nuclear (ITS1, ITS2) and mitochondrial DNA (COI, CytB, 12S rDNA, 16S rDNA) sequences was performed. Putative species in Rumina, inferred from the mitochondrial DNA phylogeny, were compared with those proposed on the basis of the COI gene by (1) DNA barcoding gap analysis, (2) Automatic Barcode Gap Discovery, (3) the species delimitation plug-in of the Geneious software, (4) the Genealogical Sorting Index, and (5) the General Mixed Yule Coalescent model. It is shown that these methods produce a variety of different species hypotheses and as such one may wonder to what extent species delimitation methods are really useful. With respect to Rumina, the data suggest at least seven species, one corresponding to R. saharica and six that are currently grouped under the name R. decollata. The species-level status of R. paivae is rejected.

Substrate attributes determine gait in a terrestrial gastropod

Some terrestrial gastropods are able to move using two gaits: adhesive crawling, where the entire foot is separated from the substrate only by a thin layer of mucus and the snail leaves a continuous mucus trail; and loping, where regions of the foot arch above the substrate and the snail leaves a discontinuous mucus trail. Loping has been interpreted as a means of rapidly escaping predators. We found that the pulmonate Cornu aspersum moved using adhesive crawling on dry acrylic or glass substrates, but loped on dry concrete or wood. Loping snails did not move more rapidly than snails using adhesive crawling. Snails moving on concrete secreted a greater volume of pedal mucus per area of trail than those moving on acrylic; locomotion on concrete thus requires greater expenditure of mucus than does locomotion on acrylic. Because loping snails deposit a smaller area of mucus per distance traveled than do snails using adhesive crawling, loping may conserve mucus when moving on porous, absorbent substrates. Members of several other terrestrial pulmonate taxa can also lope on concrete, suggesting that this plasticity in gait is widespread among terrestrial snails.

Tracing the invasion of the mediterranean land snail Cornu aspersum aspersum becoming an agricultural and garden pest in areas recently introduced

This study is the first on the genetics of invasive populations of one of the most widely spread land mollusc species known in the world, the "Brown Snail" Cornu aspersum aspersum. Deliberately or accidentally imported, the species has become recently a notorious pest outside its native Mediterranean range. We compared the spatial structure and genetic variability of invasive (America, Oceania, South Africa) versus native populations using five microsatellite loci and mitochondrial (Cyt b and 16S rRNA) genes as a first step towards (i) the detection of potential source populations, and (ii) a better understanding of mechanisms governing evolutionary changes involved in the invasion process. Results based on multivariate analysis (Discriminant Analysis of Principal Components), Bayesian statistical inference (Clustering, Approximate Bayesian Computation) and demographic tests allowed a construction of the introduction pathways of the species over recent centuries. While emigrants originated from only one of the two native lineages, the West one, the most likely scenario involved several introduction events and "source switching" comprising (i) an early stage (around 1660) of simultaneous introductions from Europe (France, Spain) towards Oceania (New Zealand) and California, (ii) from the early 18(th) century, a second colonization wave from bridgehead populations successfully established in California, (iii) genetic admixture in invasive areas where highly divergent populations came into contact as in New Zealand. Although these man-made pathways are consistent with historical data, introduction time estimates suggest that the two putative waves of invasion would have occurred long before the first field observations recorded, both in America and in Oceania. A prolonged lag period as the use of an incorrect generation time could explain such 100-150 years discrepancy. Lastly, the contrasting patterns of neutral genetic signal left in invasive populations are discussed in light of possible ways of facing novel environments (standing genetic variation versus new mutation).

Physiological relevance and contribution to metal balance of specific and non-specific Metallothionein isoforms in the garden snail, Cantareus aspersus

Variable environmental availability of metal ions represents a constant challenge for most organisms, so that during evolution, they have optimised physiological and molecular mechanisms to cope with this particular requirement. Metallothioneins (MTs) are proteins that play a major role in metal homeostasis and as a reservoir. The MT gene/protein systems of terrestrial helicid snails are an invaluable model for the study of metal-binding features and MT isoform-specific functionality of these proteins. In the present study, we characterised three paralogous MT isogenes and their expressed products in the escargot (Cantareus aspersus). The metal-dependent transcriptional activation of the three isogenes was assessed using quantitative Real Time PCR. The metal-binding capacities of the three isoforms were studied by characterising the purified native complexes. All the data were analysed in relation to the trace element status of the animals after metal feeding. Two of the three C. aspersus MT (CaMT) isoforms appeared to be metal-specific, (CaCdMT and CaCuMT, for cadmium and copper respectively). A third isoform (CaCd/CuMT) was non-specific, since it was natively recovered as a mixed Cd/Cu complex. A specific role in Cd detoxification for CaCdMT was revealed, with a 80-90% contribution to the Cd balance in snails exposed to this metal. Conclusive data were also obtained for the CaCuMT isoform, which is involved in Cu homeostasis, sharing about 30-50% of the Cu balance of C. aspersus. No apparent metal-related physiological function was found for the third isoform (CaCd/CuMT), so its contribution to the metal balance of the escargot may be, if at all, of only marginal significance, but may enclose a major interest in evolutionary studies.