Intermediate Host Of Fasciola Hepatica Research Articles

Risk of invasion and disease transmission by the Australasian freshwater snail Orientogalba viridis (Lymnaeidae): a field and experimental study

BackgroundBiological invasions pose risks to the normal functioning of ecosystems by altering the structure and composition of several communities. Molluscs stand out as an extensively studied group given their long history of introduction by either natural or anthropogenic dispersal events. An alien population of the lymnaeid species Orientogalba viridis was first sighted in 2009 in southern Spain. In its native range (Australasian), this species is one of the main intermediate hosts of Fasciola hepatica, a major worldwide trematode parasite largely affecting humans, domestic animals and wildlife.MethodsWe collected field populations of O. viridis from its native (Malaysia) and invaded (Spain) ranges. We performed detailed morphoanatomical drawings of the species and screened for natural infection of parasites. Individuals were molecularly characterized using ITS2 for comparison with existing sequences in a fine phylogeography study. We founded experimental populations at two different conditions (tropical, 26 °C and temperate, 21 °C) to study the life-history traits of exposed and non-exposed individuals to different F. hepatica isolates.ResultsWe found a 9% natural prevalence of trematode infection (98% similarity with a sequence of Hypoderaeum conoideum [Echinostomatidae]) in the Spanish field population. The haplotypes of O. viridis found in our study from Spain clustered with Australian haplotypes. Experimental infection with F. hepatica was successful in both experimental conditions but higher in tropical (87% prevalence) than in temperate (73%). Overall lifespan, however, was higher in temperate conditions (mean 32.5 ± 7.4 weeks versus 23.3 ± 6.5) and survivorship remained above 70% during the first 20 weeks. In parasite-exposed populations, life expectancy dropped from an overall 37.75 weeks to 11.35 weeks but still doubled the time for initial cercariae shedding. Cercariae shedding started at day 23 post-exposure and peaked between days 53 and 67 with an average of 106 metacercariae per snail.ConclusionsWhether O. viridis will succeed in Europe is unknown, but the odds are for a scenario in which a major snail host of F. hepatica occupy all available habitats of potential transmission foci, ravelling the epidemiology of fasciolosis. This research provides a comprehensive understanding of O. viridis biology, interactions with parasites and potential implications for disease transmission dynamics, offering valuable insights for further research and surveillance.Graphical

Laboratory Assessment of Molluscicidal Activities of Cannabis sativa, Acacia nilotica, and Tinospora cordifolia Against Snail Host of Fasciola spp.

Background: The potential molluscicidal extracts, obtained from indigenous plants Cannabis sativa, Acacia nilotica, and Tinospora cordifolia, were tested for toxicity against freshwater pulmonate snail Lymnaea acuminata, an intermediate host of Fasciola hepatica. The organic extracts had a significant effect on young snails. Materials and Methods: All organic extracts and column-purified fractions gave median lethal concentrations (19-100.05 mg/L; 24 h) that fell well within the threshold level of 100 mg/L, set for a potential molluscicide by the World Health Organization. Results: The toxicity of T. cordifolia stem acetone extract (96 h LC50: 16.08 mg/L) was more pronounced compared with C. sativa leaf ethanol extract (96 h LC50: 16.32 mg/L) and A. nilotica leaf ethanol extract (96 h LC50: 24.78 mg/L). β-caryophyllene, gallic acid, and berberine were characterized and identified as active molluscicidal components. Co-migration of β-caryophyllene (retardation factor [Rf] 0.95), gallic acid (Rf 0.30), and berberine (Rf 0.23) with column-purified parts of Cannabis sativa, Acacia nilotica, and Tinospora cordifolia on thin-layer chromatography demonstrates same Rf value, that is, 0.95, 0.30, and 0.23, respectively. Conclusion: This study indicates that these extracts thus represent potential plant-derived molluscicides that are worthy of further investigations.

Genetic characterization and regional distribution of lymnaeid snails in northern Patagonia, Argentina.

Lymnaeid snails serve as intermediate hosts for Fasciola hepatica (Linnaeus, 1758), the etiological agent of fasciolosis, which is a widespread livestock disease in Argentina. Determining their geographic distribution and identifying the snail species involved in the transmission of fasciolosis can provide crucial information for designing strategic control programs. In this context, this work aimed at genetically characterizing the species of lymnaeid snails collected in different water bodies of northern Patagonia, Argentina. To this end, 689 snails were collected in 12 sites in the provinces of Neuquén, Río Negro and Chubut, in areas where fasciolosis is endemic. According to the morphological characteristics of their valves, they were identified as Galba spp. Twenty-three of these specimens were further identified using the nuclear sequences of the internal transcribed spacers ITS-1 and ITS-2 and 18S rRNA. The results confirmed the identity of all the analyzed snails as Galba viatrix and provided evidence that studying the variable region V2 of the 18S rRNA gene is not enough to differentiate closely related species, as observed in lymnaeid snails. Both the fact that G. viatrix was the only species identified in the endemic area surveyed and previous evidence of the high prevalence of F. hepatica infestation in grazing animals in the region suggest that this species is the main intermediate host of F. hepatica. The correct identification of lymnaeid snail species has great importance to determine risk zones and develop appropriate control measures to reduce transmission, according to the different ecological characteristics of each species.

Molecular Prevalence of Larval Stages of Fasciola hepatica in Lymnaea stagnalis Species Snails in the Vicinity of the Ağrı Province

Lymnaea stagnalis known as the great pond snail, is one of the intermediate hosts of Fasciola hepatica, a zoonotic parasite. In this study, it was aimed to determine the larval forms of F. hepatica by polymerase chain reaction (PCR) in L. stagnalis species snails collected from the vicinity of Ağrı province. In this study, 150 L. stagnalis snails were collected from the Ağrı province. The freshwater snails brought to the laboratory were dissected, then their soft tissues were examined under a microscope. DNA extraction was performed on the dissected snails. After DNA extraction, PCR was performed using primers targeting the cytochrome c oxidase subunit 1 gene region. In the microscopic examination, larval forms of F. hepatica could not be detected. However, it was concluded that two (1.3%) L. stagnalis freshwater snails were infected with the larval forms of F. hepatica in the PCR. It was determined that L. stagnalis served as an intermediate host to F. hepatica in the study area.

An Integrative Approach for the Identification of Native and Exotic Lymnaeids from Brazil

Many freshwater snail species of the family Lymnaeidae are known to act as intermediate hosts of Fasciola hepatica, the causative agent of fasciolosis, a parasitic disease of great veterinary and medical importance. Morphological identification of lymnaeid species is based on characteristics of shell, reproductive and renal systems. However, such identification is challenging due to interspecific similarity, which is particularly evident among the species Galba viator, G. cubensis, and G. truncatula. To overcome these difficulties, we used molecular markers and a morphological approach applied to specimens from Brazil to compare the data obtained with type specimens, topotypes, and other lymnaeid species. We used PCR-RFLP with MboII, HpaII, and AluI enzymes directed to the ITS2-rDNA region, which allowed differentiation among Pseudosuccinea columella, Pectinidens diaphanus, G. viator, G. cubensis, and G. truncatula when morphological characterization is inconclusive. These results allowed us to report for the first time the occurrence of G. cubensis and G. truncatula in the state of Minas Gerais, Brazil. We also performed phylogenetic analyses using 16S mtDNA sequences, which corroborated the PCR-RFLP results. The molecular techniques used in this study aimed to support the morphological identification of Lymnaeidae populations from Brazil and have proven to be a helpful tool when morphological analysis does not support confident identification at the species level.

STUDY OF MOLLUSCS IN BIOTOPES ON PASTURES CONTAMINATED BY FASCIOLA HEPATICA

The mollusk Lymnaea truncatula is an intermediate host of Fasciola hepatica. However, the involvement of other mollusk species (L. stagnalis, Galba palustris, etc.) in the F. hepatica development cycle might take place. In this connection, we have studied the spread of molluscs of these species in areas contaminated by Fasciola hepatica. The research purpose was to study the infection of molluscs by Fasciola larvae in the habitats (biotopes) on pastures contaminated by trematodiasis in the Bryansk Region. We determined the population density of molluscs and their species on the pastures, and the infection dynamics of parthenita stages of F. hepatica in molluscs. The study was performed on 3 pastures of 12 to 27 hectares from April to October 2021. The following molluscs were examined: 10 to 93 specimens of the snail L. truncatula, 11 to 24 specimens of the great pond snail L. stagnalis, and 12 to 42 specimens of the aquatic snail L. palustris. Molluscs were examined for infection with Fasciola larvae by the compression method every month during the grazing period (April-October). As a result of the study, the snail L. truncatula was only found to be infected by larval stages of Fasciola. The remaining lymnaeids were free from this trematode invasion. The snail L. truncatula was more infected with Fasciola in September. The Fasciola larvae in the snail were observed in May, August and September with the infection rate of 2.3%, 3.5% and 4.3%, respectively.

Integrative taxonomy: combining molecular and morphological characteristics to identify Lymnaea (Galba) cubensis, intermediate host of Fasciola hepatica.

Despite the epidemiological importance of the Lymnaeidae family regarding transmission of Fasciola hepatica, knowledge about the diversity and distribution of these molluscs and the role of each species in the expansion of fasciolosis remains sparse. Classical morphological (n=10) identification was performed in lymneids from Lagoa Santa, a municipality in the state of Minas Gerais, Brazil, along with molecular and phylogenetic analysis (n=05) based on the partial nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I gene (COI mtDNA) and ribosomal internal transcribed spacer II (ITS-2 rDNA). The shell morphology made it possible to distinguish the lymneids of Lagoa Santa from Pseudosuccinea columella. Differences found in the penile complex and prostate shape allowed this species to be distinguished from Galba truncatula. However, the homogeneity of reproductive tract characteristics among Lymnaea (Galba) cubensis, L. viator and L. neotropica confirmed that these characteristics show low taxonomic reliability for identifying cryptic species. Genetic divergence analysis for the COI mtDNA gene and ITS-2 region of rDNA revealed greater similarity to Lymnaea (Galba) cubensis. Thus, correct species differentiation is important for monitoring the epidemiological risk of fasciolosis in the state of Minas Gerais, where cases of the disease have increased over recent years.

Reporte de Pseudosuccinea columella infectados con Fasciola hepatica en Sierra de los Cuchumatanes, Guatemala

Objetivo. Identificar la infección natural de caracoles de agua dulce con Fasciola hepatica en una localidad del altiplano de Guatemala. Materiales y métodos. Se colectaron caracoles de agua dulce en una aldea endémica de fascioliasis, en la localidad de Paquix, en el departamento de Huehuetenango, ubicado a ~3.300 msnm. La identificación de la especie de caracol se basó en las características morfológicas observadas por estereoscopio usando una clave de identificación. La búsqueda de fases del trematodo se realizó mediante la inspección visual externa con fuente de luz y la disección e inspección visual dentro del molusco bajo estereoscopio y microscopio. Resultados. 260 caracoles fueron encontrados e identificados como Pseudosuccinea columella. Se examinaron los especímenes colectados y se encontraron dos caracoles infectados de forma natural con fases larvarias de F. hepatica. Conclusiones. Este es el primer reporte de este hospedero intermediario portando formas de F. hepatica en Guatemala. Es necesario aumentar los reportes de este parásito y de sus interacciones ecológicas en otras áreas no estudiadas de Guatemala y Centro América, debido al riesgo latente de infección para poblaciones de animales herbívoros y humanos.

Ovicidal potential of Pochonia chlamydosporia isolate Pc-10 (Ascomycota: Sordariomycetes) on egg masses of the snail Pseudosuccinea columella (Mollusca: Gastropoda)

Snails of the species Pseudosuccinea columella are considered intermediate hosts of Fasciola hepatica, a digenetic trematode that infects bile ducts of ruminants and humans, causing economic damage and serious problems for public health. These gastropods inhabit ponds, have high reproductive capacity, and lay their egg masses in submerged substrates on pond edges where they are exposed to desiccation and microbes, including fungi, that may exert pathogenic effects on the snail and its embryos. This information is relevant for control of the intermediate host and therefore of fasciolosis. With the objective of evaluating ovicidal potential of Pochonia chlamydosporia (Pc-10 isolate), a nematophagous fungus used as antagonistic agent for a wide variety of helminths of medical and veterinary importance, on egg masses of P. columella, we compared a treated group, where the egg masses were exposed to Pc-10 for a period of 25 days, and a control group, in which there was no exposure to the fungus. The results indicated that the embryogenesis process was significantly inhibited (93.15%) by Pc-10, suggesting its applicability in biological control programs of lymnaeid snails. In addition, ultrastructure showed the occurrence of different types of interactions between the egg masses with the mycelia of Pc-10: type 1, biochemical effects by the adherence of hyphae; type 2, morphological alterations, but without hyphal penetration; and type 3, lytic effect, morphological damage caused by penetration of hyphae by the fungus, resulting in some important structural modifications, thus compromising the viability of the eggs. The results demonstrate the susceptibility of P. columella egg masses to an isolate of P. chlamydosporia under laboratory conditions, providing valuable information for the biological control of this intermediate host.

STUDY OF MOLLUSCS’ INFESTATION WITH FASCIOLA HEPATICA IN BRYANSK REGION

The intermediate host of Fasciola hepatica is Lymnaea truncatula mollusk. However, participation of other species of mollusks (L. stagnalis, Galba palustris, etc.) in the development cycle of F. hepatica is not excluded. In this connection, we have studied the distribution of mollusks of these species in the territory of the Bryansk region. The aim of the work was to carry out a study on the invasion of fasciol larvae of mollusks on pastures of trematodiasis-unfriendly farms of the Bryansk region. On farms, the density of mollusks and their species, as well as the dynamics of the infection of mollusks by the partenite stages of F. hepatica, were determined. The work was carried out from May to October 2018 on 3 pastures with an area of 2 to 5 hectares. The study was subjected to mollusks: small pond snail L. truncatula in the amount of from 149 to 151 specimens, ordinary pond snail – L. stagnalis from 10 to 18 specimens, marsh pond snail – L. palustris from 30 to 85 specimens, iushkoviy pond snail – L. auricularia from 4 to 21 specimens. Mollusks were examined every month during the pasture period (May-October) for infection with fasciol larvae by the compressor method. It was revealed that only small pond snail L. truncatula was infested by the larval stages of development of fasciol. The rest of the limneids were free from this trematodase invasion. The small pond snail was infected more intensely in September. The fasciol larvae of the small pond snail were recorded in May, June, August and September; the infection rate was 1.3%, 2.6%, 6.6% and 8%, respectively.

A new method for laboratory rearing of Galba truncatula, the intermediate host of Fasciola hepatica

In this study a relatively large and open top aquarium was designed, constructed and introduced as a suitable habitat for nutrition, growth and development as well as for egg laying and breeding of Galba truncatula under laboratory conditions. The soil and water used in the aquarium were collected from the locality in which the snails were collected. The aquarium was placed in a laboratory with temperature of 18–32 ºC and relative humidity of 22–37% respectively, according to the season. The artificial light was controlled by a light timer, giving 12 h of light and 12 h of darkness. The snails were fed with dried lettuce leaves, Cyperus alternifolius (aquatic plant), Spirulina (algae), Orthotrichum rupestre (moss) and cuttlebone (a supplementary source of calcium). Approximately five weeks after the start of study, there was evidence of reproduction and success in rearing of G. truncatula by the appearance of eggs and small snails (0.1–0.5 mm) in the aquarium. In conclusion, large scale laboratory rearing of G. truncatula is a feasible task. The method may be improved by balancing the temperature and relative humidity as well as by optimizing the soil type, the water quality and the type of food.

A new multiplex PCR assay to distinguish among three cryptic Galba species, intermediate hosts of Fasciola hepatica

A molecular tool described here allows in one step for specific discrimination among three cryptic freshwater snail species (genus Galba) involved in fasciolosis transmission, a worldwide infectious disease of humans and livestock. The multiplex PCR approach taken targets for each species a distinctive, known microsatellite locus which is amplified using specific primers designed to generate an amplicon of a distinctive size that can be readily separated from the amplicons of the other two species on an agarose gel. In this way, the three Galba species (G. cubensis, G. schirazensis, and G. truncatula) can be differentiated from one another, including even if DNA from all three were present in the same reaction. The accuracy of this new molecular tool was tested and validated by comparing multiplex PCR results with species identification based on sequences at mitochondrial and nuclear markers. This new method is accurate, inexpensive, simple, rapid, and can be adapted to handle large sample sizes. It will be helpful for monitoring invasion of Galba species and for developing strategies to limit the snail species involved in the emergence or re-emergence of fasciolosis.

Antifungal, molluscicidal and larvicidal assessment of anemonin and Clematis flammula L. extracts against mollusc Galba truncatula, intermediate host of Fasciola hepatica in Tunisia.

To investigate the potential of anemonin and Clematis flammula (C.flammula) extracts against infective organisms. The molluscicidal activities of anemonin and C.flammula extracts against Galba truncatula Müll. (Lymnaeidae) and Fasciola hepatica larval stages contaminating this snail in Tunisia were assessed by testing six groups of snails in 250mL of extracts and aqueous dechlorinated solutions with different concentrations (ranging from 2.5 to 20.0mg/L) for 48h. Besides, the antifungal potential of C.flammula leaves and flowers was evaluated by using the diffusion agar and broth dilution methods against four fungal strains: Aspergillus niger, Pythium catenulatum, Rhizoctonia solani and Fusarium phyllophilum. As a result, hexane and ethyl acetate flower extracts exhibited significant molluscicidal activities with LC50 median lethal concentrations values of 11.87 and 11.65mg/L, respectively while LC50 value of anemonin was 9.64mg/L after 48h exposure. The flower extracts showed a larvicidal effect with a deterioration rate exceeding 35.39% where flower ethyl acetate residue gave a deterioration rate of cercariae close to 97%. Moreover, C.flammula extracts were not noxious to the associated fauna survival. All extracts inhibited the growth of P. catenulatum, the leaves and flowers methanolic extracts had the more important fungicide action with minimum inhibitory concentrations of 1.56 and 3.12mg/mL together with minimum fungistatic concentrations of 3.12 and 6.25mg/mL respectively. Only flower extracts were active against Rhizoctonia solani with minimum inhibitory concentrations varying between 0.70 and 1.56mg/mL and 6.25mg/mL of minimum fungistatic concentration. Phytochemical tests showed that the antifungal activity may be attributed to the presence of the flavonoids/saponins in the methanolic extracts and the molluscicide effects could be due to the richness of hexane and ethyl acetate extracts on sterols and triterpenoids. This study emphasizes the important molluscicidal and antiparasitic effects of flower ethyl acetate extracts and anemonin compound as well as the considerable antifungal activities of methanolic extracts. These results improve the therapeutic virtues of C.flammula aerial part extracts.

Molluscicidal activity of four Apiaceae essential oils against the freshwater snail Radix peregra

Snails of the family Lymnaeidae are an essential link in the transmission of zoonotic diseases. Radix peregra is a European freshwater snail and a susceptible intermediate host of Fasciola hepatica, the causing agent of fascioliasis. Essential oils (EOs) extracted from Anethum graveolens (dill), Cuminum cyminum (cumin), Foeniculum vulgare var. vulgare (bitter fennel) and Petroselinum crispum (plain leaf parsley) were characterized by GC and GC–MS. Seven EOs and 11 constituents were first screened through a single-dose bioassay against R. peregra (10 mg L−1 for juveniles and 50 mg L−1 for egg masses and mature snails). EOs from parsley, cumin and bitter fennel (leaves plus stems) were highly active towards eggs and adults at 50 mg L−1. Subsequently, dose and time–lethality bioassays were performed against adults to determine lethal parameters (LC50;90 and LT50;90). Estimated 48 h LC50s varied from 13.7 to 46.5 mg L−1, with P. crispum fruits EO exhibiting the most significant activity. EOs from cumin fruits and bitter fennel infrutescences, and cuminaldehyde, were the most time-effective treatments when assessed by continuous exposure (LT50 for a 50 mg L−1 dose = 15.1, 19.3 and 19.5 h, respectively). A short-time exposure (8 h) to bitter fennel EOs was effective for the control of adults (LT50 ≤25 h). The present study uncovers the potential of four well-known Apiaceae species as natural sources of biomolluscicides.

Self-fertilization, long-distance flash invasion and biogeography shape the population structure of Pseudosuccinea columella at the worldwide scale.

Population genetic studies are efficient for inferring the invasion history based on a comparison of native and invasive populations, especially when conducted at species scale. An expected outcome in invasive populations is variability loss, and this is especially true in self-fertilizing species. We here focus on the self-fertilizing Pseudosuccinea columella, an invasive hermaphroditic freshwater snail that has greatly expanded its geographic distribution and that acts as intermediate host of Fasciola hepatica, the causative agent of human and veterinary fasciolosis. We evaluated the distribution of genetic diversity at the largest geographic scale analysed to date in this species by surveying 80 populations collected during 16years from 14 countries, using eight nuclear microsatellites and two mitochondrial genes. As expected, populations from North America, the putative origin area, were strongly structured by selfing and history and harboured much more genetic variability than invasive populations. We found high selfing rates (when it was possible to infer it), none-to-low genetic variability and strong population structure in most invasive populations. Strikingly, we found a unique genotype/haplotype in populations from eight invaded regions sampled all over the world. Moreover, snail populations resistant to infection by the parasite are genetically distinct from susceptible populations. Our results are compatible with repeated introductions in South America and flash worldwide invasion by this unique genotype/haplotype. Our study illustrates the population genetic consequences of biological invasion in a highly selfing species at very large geographic scale. We discuss how such a large-scale flash invasion may affect the spread of fasciolosis.

A study of the molluscicidal and larvicidal activities of Citrullus colocynthis (L.) leaf extract and its main cucurbitacins against the mollusc Galba truncatula, intermediate host of Fasciola hepatica.

The molluscicidal and larvicidal activities of the medicinal plant Citrullus colocynthis leaf extracts and its main cucurbitacins were tested against the mollusc gastropod Galba truncatula, the intermediate host of Fasciola hepatica. Our findings proved for the first time that the molluscicidal activity was correlated with the presence of terpenoids. A significant molluscicidal value was found in the ethyl acetate extract (LC50 = 12.6 mg L-1 ). Further fractionation of this extract led to the isolation of two main compounds identified to cucurbitacin E 1 and 2-O-β-d-glucocucurbitacin E 2. Their molluscicidal activities were also investigated and they possessed close activities with LC50 = 9.55 and 10.61 mg L-1 for compounds 2 and 1, respectively. The ethyl acetate extract and both pure compounds proved the highest larvicidal activities, with a deterioration rate exceeding 89.2% (89.2-100%) and with no toxic effects against associated fauna. © 2016 Society of Chemical Industry.

Validation of an interactive map assessing the potential spread of Galba truncatula as intermediate host of Fasciola hepatica in Switzerland.

Bovine fasciolosis, caused by Fasciola hepatica, is widespread in Switzerland. The risk regions were modelled in 2008 by an interactive map, showing the monthly potential risk of transmission of F. hepatica in Switzerland. As this map is based on a mathematical model, the aim of the present study was to evaluate the interactive map by means of a field survey taking different data sources into account. It was found that the interactive map has a sensitivity of 40.7-88.9%, a specificity of 11.4-18.8%, a positive predictive value of 26.7-51.4%, and a negative predictive value of 13.1-83.6%, depending on the source of the data. In conclusion, the grid of the interactive map (100 x 100 m) does not reflect enough detail and the underlying model of the interactive map is lacking transmission data.

The population density of Lymnaea columella (Say, 1817) (Mollusca, Lymnaeidae) an intermediate host of Fasciola hepatica (Linnaeus, 1758), in the Caparaó microregion, ES, Brazil

The aim of this study was to monitor the population density of Lymnaea columella, an intermediate host of Fasciola hepatica, in various aquatic habitats and in drinking water in the area of the Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo, on Caparaó Microregion, municipality of Alegre, state of Espírito Santo, Brazil. Monthly samplings were performed at certain points between drainage areas and drinking water in cattle and goat production systems during the years 2010 to 2013. The mean temperature, precipitation and the frequency of samples of L. columella were analysed graphically according the monthly average during the study period. A total of 2,038 molluscs were collected, 1558 of which were L. columella, that predominated in all sampled points. The highest average of specimens observed for L. columella was in the years 2010 and 2013 (51.0), and occurred decreased in 2011 (19.8). The temperature and precipitation averaged is 23.7 °C and 141 mm/year, respectively. Rainfall peak occurred in March (2011, 2013) and November (2012), during these periods the population of L. columella growth. There was no significant difference in the relationship between the specimens observed with seasons (dry-wet), thus the population of L. columella remained stable and can be found throughout the year.

Characterisation of Pseudosuccinea columella and Radix natalensis (Gastropoda: Lymnaeidae) in Egypt using shell and molecular data

ABSTRACTPseudosuccinea columella and Radix natalensis live in the same habitat in Egypt and are important intermediate hosts of Fasciola hepatica and F. gigantica. Our study aimed to characterise both snail species using molecular analysis and shell measurements. The ranges of morphometric parameters overlapped in the two lymnaeids, indicating that they do not clearly differentiate the two species. PCR-sequence analysis of the nuclear ribosomal small subunit rRNA and the polymorphic mitochondrial cytochrome oxidase subunit 1 (CO1) genes were used to determine the genetic identity and the potential diversity of the snails. Little intrasequence variations were detected in the sequences of both gene loci, indicating the potential homogeneity of lymnaeid populations in Egypt. Generated sequences of the mitochondrial CO1 gene locus for R. natalensis showed obvious heterogeneity compared to other sequences in GenBank. Molecular characterisation of these lymnaeids might help to understand the snails’ biodiversity in a bid to control these populations and their related diseases.

Molluscicidal activity of Solanum elaeagnifolium seeds against Galba truncatula intermediate host of Fasciola hepatica: Identification of β-solamarine

Context: The persistence of fascioliasis in many developing countries urges the search for simple, cheap, and effective substances. In this view, plants provide interesting molluscicidal activities thanks to the secondary metabolites they produce. The genus Solanum is known for its potent effect on vector snails.Objective: The molluscicidal activity of Solanum elaeagnifolium Cav. (Solanaceae) seeds against Galba truncatula Müll. (Lymnaeidae), intermediate host of Fasciola hepatica L. (Fasciolidae), was evaluated.Materials and methods: Solanum elaeagnifolium seeds were powdered and successively extracted using n-hexane, methylene chloride, acetone, and methanol, for 20 h each. After filtration, solvents were evaporated. An acid–base treatment was conducted on seed methanolic extract to isolate total alkaloids and β-solamarine. Total saponins fraction was obtained after successive macerations and evaporations. The molluscicidal activity was evaluated by subjecting snails, in groups of 10, for 48 h to 500 mL of extracts, fractions, and pure product aqueous solutions, each containing amounts, ranging from 1 to 50 mg of plant material in 5 mg increments.Results: The methanolic extract of seeds, β-solamarine isolated for the first time from this plant and total saponins fraction showed very potent activities on snails, giving respective median lethal concentrations (LC50) of 1.18, 0.49, and 0.94 mg/L. Total alkaloids fraction obtained from the methanolic extract was less active giving an LC50 value of 14.67 mg/L.Discussion and conclusion: This study emphasizes that glycoalkaloids and saponins of Solanum elaeagnifolium are potent molluscicidal agents. Seed methanolic extract, β-solamarine, and total saponins fraction may be used as molluscicides.