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1
Ademolu, K. O., A. B. Idowu e O. A. Jayeola. "Changes in Haemolymph Biochemical values during different growth phases in African Giant Land Snail (Archachatina Marginata) Swainson". Nigerian Journal of Animal Production 36, n. 1 (1 gennaio 2021): 161–66. http://dx.doi.org/10.51791/njap.v36i1.1200.
Testo completoAbstract (sommario):
The impact of growth phases on the haemolympy biochemical value of African giant land snail Archachatina marginata was studied. The growth phases were: snailet, juvenile and Adult based on the number of whorls on the shell and weight of the snails. Highest concentration of glucose and lipids were recorded at the juvenile phase (40.20mg/dl), while least values for glucose (20.00mg/dl) and lipids (37.80mg/dl)were recorded during snailer and adult phases respectively. A progressive increase in the concentration of protein was observed as the snails moved from snailetphase to adult phase, hence snails in adult phase had highest concentration of protein in their haemolymph. Growth phases significantly (p<0.05) affected the haemolymph mineral composition of the snails, juvenile phase had the highest values in ca2+,PO4+ and Na+, while the adult phase recorded the least concentration in ca2+, Na amd cl-2. Juvenile growth phase of A. marginata thus has better haemolymph biochemical values than both snailet and adult growth phases.
2
Ito, Shun, e Junji Konuma. "Disruptive selection of shell colour in land snails: a mark–recapture study of Euhadra peliomphala simodae". Biological Journal of the Linnean Society 129, n. 2 (3 dicembre 2019): 323–33. http://dx.doi.org/10.1093/biolinnean/blz168.
Testo completoAbstract (sommario):
Abstract Many theoretical studies have suggested that disruptive selection plays an important role in phenotypic divergence, but few studies have determined the action of disruptive selection on phenotypic divergence via field studies. This study investigated the effect of disruptive selection on shell colour polymorphism in the Japanese land snail Euhadra peliomphala simodae to determine whether extreme phenotypes of snail shell colour are favoured over intermediate phenotypes. We conducted field surveys on an oceanic island with black, yellow and intermediate-coloured E. p. simodae snails. We captured and marked ~1800 individual snails and monitored their survival over 18 months. We quantified shell colours against images and examined the frequency distribution of shell colour variation. The variation exhibited a bimodal distribution with a far lower frequency of intermediate-coloured snails than of black or yellow snails. The population sizes of the three snail groups fluctuated synchronously with the changing seasons. Bayesian estimates showed lower survival rates for juvenile intermediate-coloured snails than for juvenile black and yellow snails, implying there was disruptive selection associated with shell colour. We suggest this disruptive selection may have resulted in the evolutionary divergence of the snail’s shell colour within the lineage having high shell colour variation.
3
Zayed, Khaled M., Yun-Hai Guo, Shan Lv, Yi Zhang e Xiao-Nong Zhou. "Molluscicidal and antioxidant activities of silver nanoparticles on the multi-species of snail intermediate hosts of schistosomiasis". PLOS Neglected Tropical Diseases 16, n. 10 (10 ottobre 2022): e0010667. http://dx.doi.org/10.1371/journal.pntd.0010667.
Testo completoAbstract (sommario):
Background Schistosomiasis, also known as bilharzia, is the second important parasitic disease after malaria. The present study aimed to evaluate the molluscicidal effects of silver nanoparticles on Biomphalaria alexandrina, B. glabrata, Oncomelania hupensis, snail intermediate hosts of intestinal schistosomes (i.e. Schistosoma mansoni and S. japonicum), along with the changes their antioxidant enzymes. Methods Silver (Ag) nano powder (Ag-NPs) was selected to test the molluscicidal effects on three species of freshwater snails. Exposure to Ag-NPs induced snail mortality and the LC50 and LC90 values of Ag-NPs for each snail species were calculated by probit analysis. Control snails were maintained under the same experimental conditions in dechlorinated water. Snail hemolymph was collected to measure the levels of antioxidant enzymes, such as total antioxidants capacity (TCA), glutathione (GSH), catalase (CAT) and nitric oxide (NO). In addition, the non-target organism, Daphnia magna, was exposed to a series of Ag-NPs concentration, similar to the group of experimental snails, in order to evaluate the LC50 and LC90 and compare these values to those obtained for the targeted snails. Results The results indicated that Ag-NPs had a molluscicidal effect on tested snails with the variation in lethal concentration. The LC50 values of Ag-NPs for B. alexandrina snails exposed for 24, 48, 72 hrs and 7 days were 7.91, 5.69, 3.83 and 1.91 parts per million (ppm), respectively. The LC50 values for B. glabrata snails exposed for 24, 48, 72 hrs and 7 days were 16.55, 10.44, 6.91 and 4.13 ppm, respectively, while the LC50 values for O. hupensis snails exposed for 24, 48, 72 hrs and 7 days were 46.5, 29.85, 24.49 and 9.62 ppm, respectively. Moreover, there is no mortality detected on D. magna when exposed to more than double and half concentration (50 ppm) of Ag-NPs during a continuous period of 3 hrs, whereas the LC90 value for B. alexandrina snails was 18 ppm. The molluscicidal effect of the synthesized Ag-NPs seems to be linked to a potential reduction of the antioxidant activity in the snail’s hemolymph. Conclusions Synthesized Ag-NPs have a clear molluscicidal effect against various snail intermediate hosts of intestinal schistosome parasites and could potentially serve as next generation molluscicides.
4
Napoli, Ettore, Alessandra Sfacteria, Claudia Rifici, Giuseppe Mazzullo, Gabriella Gaglio e Emanuele Brianti. "Reaction of Cornu aspersum Immune System against Different Aelurostrongylus abstrusus Developmental Stages". Pathogens 12, n. 4 (31 marzo 2023): 542. http://dx.doi.org/10.3390/pathogens12040542.
Testo completoAbstract (sommario):
Cornu aspersum, the land snail, is recognized as a suitable intermediate host of Aelurostrongylus abstrusus; however, there is little information both on larval development as well as on the intermediate host’s immune system reaction to the parasite. The aim of the study was to assess the histological reaction of C. aspersum’s immune system against A. abstrusus. Sixty-five snails were provided by a snail farm. Five of them were digested to assess the absence of natural parasitic infections. The remaining sixty were divided into five groups. Three groups of snails were infected with A. abstrusus using by-contact or injection methods; one group was injected only with saline solution and one group was left untreated as the control. The snails of group A were sacrificed and digested on study days 2, 10, and 18; snails of the other groups were collected and examined for histopathological analysis on study days 2, 10, and 18. On study day 2, in the infected snails, several free L1s were observed along with the absence of immune system reactions. On day 10, the L2s elicited an intense reaction in the internal layer of the muscular foot. On day 18, all L3s partially encapsulated by the snail’s immune system were observed in the outermost part of the muscular foot, which is near and among the goblet cells. This last finding suggests that L3s could be shed with the snail’s mucus and spread in the environment, representing an alternative route of transmission for this feline lungworm.
5
Hoso, Masaki, Takahiro Asami e Michio Hori. "Right-handed snakes: convergent evolution of asymmetry for functional specialization". Biology Letters 3, n. 2 (13 febbraio 2007): 169–73. http://dx.doi.org/10.1098/rsbl.2006.0600.
Testo completoAbstract (sommario):
External asymmetry found in diverse animals bears critical functions to fulfil ecological requirements. Some snail-eating arthropods exhibit directional asymmetry in their feeding apparatus for foraging efficiency because dextral (clockwise) species are overwhelmingly predominant in snails. Here, we show convergence of directional asymmetry in the dentition of snail-eating vertebrates. We found that snakes in the subfamily Pareatinae, except for non-snail-eating specialists, have more teeth on the right mandible than the left. In feeding experiments, a snail-eating specialist Pareas iwasakii completed extracting a dextral soft body faster with fewer mandible retractions than a sinistral body. The snakes failed in holding and dropped sinistral snails more often owing to behavioural asymmetry when striking. Our results demonstrate that symmetry break in dentition is a key innovation that has opened a unique ecological niche for snake predators.
6
Weck, Robert G. "Life history observations of the Illinois state endangered Enigmatic Cavesnail, Fontigens antroecetes (Hubricht, 1940) made under simulated cave conditions". Subterranean Biology 43 (3 agosto 2022): 185–98. http://dx.doi.org/10.3897/subtbiol.43.87277.
Testo completoAbstract (sommario):
The Enigmatic Cavesnail, Fontigens antroecetes (Hubricht, 1940), is a cave adapted hydrobioid snail listed as state endangered in Illinois. It is known from only one cave in Illinois, Stemler Cave, and from several caves in the eastern Ozark ecoregion of Missouri. Little is known about the snail’s reproductive habits, embryological development, or growth rates. I attempted to gain basic life history information by breeding Enigmatic Cavesnails under simulated cave conditions in the laboratory. Six adult snails were collected from Stemler Cave and held in aerated containers of cave water with one or two cobbles from the cave stream. Containers of snails were housed in incubators set at the average cave water temperature of 13 °C. The snails produced 49 embryos in captivity over the course of 34 weeks. Eggs were deposited singly, attached to the underside of rocks within small pits or crevices. Nearly 82% of embryos developed to hatching. Mean estimated development time of embryos was 70.7 days. Survival of hatchling snails was poor. Limited data available from surviving hatchling snails suggests slow growth rates. The process was replicated with nine Enigmatic Cavesnails collected from Cliff Cave in St. Louis County MO. Captive Cliff Cave snails produced 34 embryos over 46 weeks and varied from the Stemler population in their oviposition behavior, with a majority of eggs deposited on the top surface of rocks. Cliff Cave snail embryos also had longer mean estimated development times (82.17 days).
7
Götz, Matthias. "The feeding behavior of the snail-eating snake Pareas carinatus Wagler 1830 (Squamata: Colubridae)". Amphibia-Reptilia 23, n. 4 (2002): 487–93. http://dx.doi.org/10.1163/15685380260462383.
Testo completoAbstract (sommario):
AbstractThe behavior of captive Pareas carinatus feeding on European round-shelled snails is described. The snake bites into the snail's body and lifts it from the ground. With alternate retraction movements of the mandibles, it pulls the body out of the shell while the upper jaw rests on the outside of the shell. There are only slight differences to dipsadine snakes: Pareas never followed a mucus track and did not coil around the snail's shell. There seemed to be a preference to catch the snails from behind. Extraction time (24-390 s) and number of mandibular movements (22-98) were similar to the data on the dipsadines.
8
Dragicevic, Olgica, e Milan Baltic. "Snail meat: Significance and consumption". Veterinarski glasnik 59, n. 3-4 (2005): 463–74. http://dx.doi.org/10.2298/vetgl0504463d.
Testo completoAbstract (sommario):
The consumption of snail meat goes back to prehistoric times. Different ancient nations had snails on their menu, but Helices culture as a productive activity was born as a Roman culture. Some of the most economically important edible species are: Helix aspersa (Mtiller) Helixpomatia (Linne), Helix iucorum (Linne), Helix aperta (Born), Eobania vermiculata (Miiller). Together with its tasie, snail meat has several advantages over others: quite low lipid rate and calorie values versus rich mineral, essential amino acid and fatty acid content. The composition of snail meat is presented. In addition, the composition of different snail species and the part analyzed (pedal mass and visceral mass) is presented. Also, the differences in composition according to the species (snail meat horse/chicken meat, beef, swine meat, fish meat) are presented. The French are the world's leading consumers of snails. !n France snails come to market in a variety of ways. Estimated consumption of snails in France is around 40 000 tones/year. Total French imports account for 25% of world imports. France is also the leading exporter of prepared snails, mainly sold as preserved snails and prepared dishes. Snail imports have been much higher than exports (65 tones exported in 2002. vs. 2.700 tones imported). Despite the large consumption, only 3% of snails in France come from production (farming). Italy is in second place in the world consumption of snails, and Spain and Germany are in the third and fourth place. The development of snails consumption in Italy is followed with the same amount of production of snails in the whole biological circle. In 2001, from 24,700 tons, 9,350 tons (37.8%) came from production, 6 00 tons (2.4%) came from nature, and 14,750 tons (59.70%) came from imports (frozen, fresh and prepared snails). In Serbia, at the beginning of 2005, we had over 400 registered farms for snail production.
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Danilova, I. S. "Study of toxicness of snails meat on biological model". Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 21, n. 94 (30 luglio 2019): 57–60. http://dx.doi.org/10.32718/nvlvet9410.
Testo completoAbstract (sommario):
Snails can be found in any part of the planet. They belong to the class of gastropods, which includes terrestrial, freshwater, marine snails. Their ancestors are some of the most ancient species of the fauna. Archaeologists say that the first lived on our planet 500 million years ago. There are about 90000 species of snails, but only 3 species have gained worldwide fame: gigantic African snail, grape and Helix аspersa. Snail’s meat improves bowel function and normalizes metabolism. It is believed that due to the content of magnesium, snail meat has calming effect on humans and helps to fight stress. To determine the level of toxicity of food snails meat on a biological model. Helix pomatia snails were collected in wet weather, after rain or in the morning, Helix aspersa maxima and Helix aspersa muller were recieved from the farm “SNAIL 2016” (Ukraine). As a model we used white mise. To determine the toxicity, the sampled meat preparation has been conducted. For this purpose an average sample of meat of each snail types of 10.0 g, carefully chopped. The milled sample of 5.0 g was introduced into a sterile glass, poured 50.0 cm3 of distilled water, stirred and filtered. There were formed experimental 6 and 2 control groups of mice were formed by six in each one, of 2 months of age (body weight 20 g). Subsequently, prepared samples of snails meat were injected into the mice stomach through a probe every day for 3 days by 0.5 cm3. As a probe, a thin, single-use micropipette was used. The white mice of each group experimental of all groups were placed in isolated cages and clinically monitored for five days. The mice didn’t recieved food, animals had free access to water. Mice of the control groups had free access to food. The meat of each type of snails in the experiments was used both fresh and after 7 days storage refrigerator at a temperature of 4 °С. It was found that filtrates from fresh meat of the three types of food snails Helix aspersa maxima, Helix aspersa muller and Helix pomatia were non-toxic, for the mice of I, II and III groups. We have noticed that the meat that was stored for 7 days in the refrigerator at a temperature of 4 °C was toxic. Mice of the V–VII groups that were fed such meat had a depressed state, muscle tremor, they refused of water and died on 2nd and 3rd days. The mise of control groups (IV and VIII) remained during all experience remained living. This work can be used as a method for determining the toxicity of snail’s meat. It is technologically simple, it requires only laboratory animals, namely white mice, does not require special equipment. Only 3 days can get the result. The method can be used in the work of scientific-experimental, production and regional laboratories of veterinary medicine.
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Syukur, Djunaedil, e Christine Christine. "Faktor Lingkungan Fisik yang Berhubungan dengan Karakteristik Onchomelania hupensis linduensis Vektor Schistosomiasis di Kecamatan Lindu". Banua: Jurnal Kesehatan Lingkungan 2, n. 1 (30 giugno 2022): 23–30. http://dx.doi.org/10.33860/bjkl.v2i1.498.
Testo completoAbstract (sommario):
Background: Lindu Plateau is surrounded by mountains and protected forests and there is a lake that is the source of community life and habitat for Oncomelania hupensis linduensis (OHL), an intermediate host for schistosomiasis. Purpose: To determine the relationship between environmental temperature, air humidity, turbidity and water pH with density, physical/morphological characteristics and the presence of parasites in OHL snails in active focus areas in Lindu District. Method: Analytical research with an observational survey approach, in Lindu District from May to October 2019. The population was OHL snails in Lindu District, sampled by accidental sampling in 5 research locations, namely Tomado, Langko, Anca, Puroo and Oluu villages. Result: Chi-square test with α=0.05 on environmental temperature and OHL snail density p-value=0.447, ambient temperature and OHL snail external morphology p-value=0.04, temperature and presence of cercariae parasites on OHL snails p -value=0.004; humidity and density of OHL snails p-value=0.193, humidity and external morphology of OHL snails p-value=0.17, humidity and presence of cercariae parasites in OHL snails p-value=0.175; water turbidity and OHL snail density p-value=1,000, water turbidity and OHL snail external morphology of OHL snails p-value=0,070, water turbidity and presence of parasites on OHL snails p-value=0,000; pH of Water and OHL snail density p-value=0,328, pH of water and external morphology of OHL snails p-value=0,017, pH of water with the presence of parasites on OHL snail p-value=0,430. Conclusion: Environmental temperature was related to external morphological characteristics and the presence of parasites in OHL snails, water turbidity related to the presence of parasites in OHL snails, water pH related to external morphological characteristics of OHL in the active focus areas. The government is advised to disseminate information about the active focus areas of OHL snails to prevent schistosomiasis infection in the community.
11
Hoso, Masaki. "Asymmetry of mandibular dentition is associated with dietary specialization in snail-eating snakes". PeerJ 5 (2 marzo 2017): e3011. http://dx.doi.org/10.7717/peerj.3011.
Testo completoAbstract (sommario):
BackgroundIn vertebrates, the left-and-right pairs of homologous organs are generally present in equal numbers. A remarkable exception is snail-eating snakes in the family Pareidae: almost all the pareid snakes have much more teeth on the right mandible than on the left for functional specialization in feeding on the dextral majority of land snails. Because the only exceptional species with symmetric dentition has been regarded as a slug-eater, the extent of dietary specialization on slugs could shape the degree of the lateral asymmetry of mandibular dentition (dentition asymmetry) even among snail eaters.MethodsTo test this, I compared the morphology and behavior of two sympatric species of Taiwanese snail-eating snakes,Pareas atayalandP. formosensis.ResultsSpecimens collected in the same locality showed that the dentition asymmetry ofP. formosensiswas significantly smaller than that ofP. atayal. Congruent to its weak asymmetry,P. formosensisshowed a strong preference of slugs to snails in the feeding experiment.DiscussionThe dietary specialization ofP. formosensison slugs would contribute to niche partitioning from the sympatric congenerP. atayal. This study suggests that the diverse variation in the dentition asymmetry of pareid snakes is the result of their dietary specialization and divergence.
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Bonnemain, Bruno. "Helix and Drugs: Snails for Western Health Care From Antiquity to the Present". Evidence-Based Complementary and Alternative Medicine 2, n. 1 (2005): 25–28. http://dx.doi.org/10.1093/ecam/neh057.
Testo completoAbstract (sommario):
The land helix, or snail, has been used in medicine since antiquity and prepared according to several formulations. This historical report traces the understanding of their properties from the time of Hippocrates, who proposed the use of snail mucus against protoccle and Pliny who thought that the snail increased the speed of delivery and was “a sovereign remedy to treat pain related to burns, abscesses and other wounds”, Galien recommended snails against hydrops foetails. In the 18th century, various snail “preparations” were also recommended for external use with dermatological disorders and internally for symptoms associated with tuberculosis and nephritis. Surprisingly, the 19th century saw a renewed interest in the pharmaceutical and medical use of snails with numerous indications for snail preparations. This interest in snails did not stop at the end of the 19th century. The 1945 edition of Dorvault devotes an entire paragraph to snails, indicating that the therapeutic usage of snails was still alive at that time. Recently the FDA has also shown an interest in snails. Ziconotide (SNXIII), a synthetic peptide coming from snail venom, has been under FDA review since 1999. Pre-clinical and clinical studies of this new drug are promising.
13
Heryanto, Heryanto. "Land snails on two different sides of Mt. Galunggung". BIO Web of Conferences 19 (2020): 00007. http://dx.doi.org/10.1051/bioconf/20201900007.
Testo completoAbstract (sommario):
It has been 32 years since the eruption of Mount Galunggung that the land snail diversity in the area were examined, not only in the stricken area but also in the secure place on the other side. The recent collection found 250 snails of 10 families (29 species). In the impacted area, 15 species (154 individuals) of land snails were discovered, whereas 18 species (96 individuals) were discovered in the unimpacted area. By a t-Student statistical analysis (95% confidence interval) for comparison between area of equal variances it was discovered that the two area differ significantly. The analysis was continued by using NMDS of PAST to show the difference more detail. This research proves that the snail assemblage in the impact area of eruption area were different with the snail’s assemblage in the unimpacted other side of the Mount.
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Raimi, C. O., e A. C. Odeyemi. "Organoleptic evaluation of Archachatina marginata fed rumen content dietary inclusion". Nigerian Journal of Animal Production 46, n. 4 (25 dicembre 2020): 84–88. http://dx.doi.org/10.51791/njap.v46i4.999.
Testo completoAbstract (sommario):
There is inadequate information on quality feedstuff for large scale production and all year round availability of snails in Nigeria.The research was conducted to investigate the organoleptic properties of the African giant land snails (Archachatina marginata). Thirtytwo snails were randomly allotted into four dietary treatments of varied levels of 0%, 5%, 10% and 15% rumen content inclusion. Each treatment was replicated with four snails per pen in a completely randomized design. The snails were reared in mini paddock. Feed and water were supplied ad-libitum. At the end of the eight weeks period of feeding trials, two snails were harvested at random from the replicates of each of the four treatments, sacrificed, processed and analyzed. Based on appearance, taste and aroma of the snails fried and stewed with spices and the other one steamed with spices, preference ranking in descending order revealed 15% (6·85) rumen content inclusion had the highest mean preference followed by 5% (6·53) inclusion for the fried snail with spices and 0% (6.65) inclusion had the highest ranking followed by 15% (6.53) rumen content inclusion for the snail steamed with spices. The treatments had no appreciable effect on the nutrient composition and sensory quality of the snail meat. It can be concluded that growing snails can utilize rumen content inclusion thereby increasing the feed data base for snail production in the Tropics.
15
N'guessan Olivier N'GUESSAN, Kouadio Daniel KOUASSI e Jean Baptiste AMAN. "Evaluation of the effect of herbicides on African giant snails: Case of glyphosate on Achatina achatina". World Journal of Advanced Research and Reviews 16, n. 1 (30 ottobre 2022): 383–88. http://dx.doi.org/10.30574/wjarr.2022.16.1.0991.
Testo completoAbstract (sommario):
The study carried out on the snail Achatina achatina at the achatinicole farm of the Université Jean Lorougnon guédé aimed to evaluate the effect of glyphosate on the weight and shell growth of this snail. After acclimatization in the breeding tanks for four (4) weeks, 210 snails were divided into seven (7) batches of 30 snails each. These snails are regularly watered and fed every other day with fresh lettuce leaves soaked or not in a diluted solution of glyphosate at different doses: D0, D4, D6, D8, D10, D12 and D14. The weight and shell measurement is done every two weeks. The results obtained show that the weight and linear growth of snails are inhibited according to the dose of glyphosate. All snails exposed to the product are directly impacted. The use of this product by farmers could reduce the availability of snails in orchards and consequently lead to a shortage of snail meat on the markets. In order to anticipate this ecological and environmental problem, this study must be extended to all giant snails consumed in Côte d'Ivoire.
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Miller, Aroha A., e Robert Poulin. "Parasitism, movement, and distribution of the snail Diloma subrostrata (Trochidae) in a soft-sediment intertidal zone". Canadian Journal of Zoology 79, n. 11 (1 novembre 2001): 2029–35. http://dx.doi.org/10.1139/z01-167.
Testo completoAbstract (sommario):
Despite reports of their effects on host reproduction, growth, survival, and habitat use, the role of parasites in determining community structure is still poorly understood. Trematode infections in snails are a ubiquitous feature of intertidal systems worldwide. In this study, the influence of a trematode parasite on the movement and dispersal of the trochid snail Diloma subrostrata on a soft-sediment shore is examined using markrecapture experiments. The natural densities and shell widths of the snail peak between the upper and lower portions of the intertidal zone; marked snails were released within this area. Parasitized snails tended to have larger shells than nonparasitized conspecifics, and larger snails tended to move a greater linear distance than smaller snails in the 24 h following their marking and release. After shell width was corrected for, parasitized snails were found to move a significantly shorter distance than nonparasitized snails. In addition, the mean direction chosen by parasitized snails was almost parallel to the water's edge, whereas that taken by nonparasitized snails was almost directly toward the upper portion of the intertidal zone. Although the mean directions taken by the two types of snails were statistically different, the considerable scatter in the distributions of directions taken by individual snails casts a doubt over the biological significance of the result. Without detailed knowledge of the parasite's full life cycle it is difficult to determine whether this small bias in the direction of dispersal is an adaptive manipulation of snail behaviour by the parasitic trematode. Nevertheless, these results show that the trematode limits the range of movement, and possibly the direction of movement, of parasitized D. subrostrata, and can therefore contribute to the spatial structuring of the snail population.
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Rondelaud, D., P. Vignoles e G. Dreyfuss. "Parasite development and visceral pathology inGalba truncatulaco-infected withFasciola hepaticaandParamphistomum daubneyi". Journal of Helminthology 81, n. 3 (settembre 2007): 317–22. http://dx.doi.org/10.1017/s0022149x07818542.
Testo completoAbstract (sommario):
AbstractHistological investigations inGalba truncatulanaturally or experimentally co-infected withFasciola hepaticaandParamphistomum daubneyiwere carried out to study parasite development and the responses of the digestive gland and kidney of snails, as larval forms of these digeneans often use these two sites for their growth within the snail's body. The number of live rediae per snail ranged from 2.4 to 4.2 for the dominating parasite (it developed in the digestive gland) and was less than 2.0 for the other species. When the dominating species wasF. hepatica, most snails harboured cercariae-containing rediae; if this parasite wasP. daubneyi, procercariae-containing rediae with or without free procercariae were observed in most snails. In contrast, most rediae of the other species were immature. The pathology caused by the dominating species in the digestive gland was greater than that recorded in the kidney, where the other parasite was generally located. The most frequent tissue lesions in the digestive gland were generalized epithelial necrosis and epithelial reconstitution. In the kidney, multifocal epithelial necrosis was frequently observed, particularly whenP. daubneyiwas the dominating species. The frequencies of lesions in the digestive gland agreed with percentages reported by our team in other snails mono-infected withF. hepaticaorP. daubneyi. In contrast, multifocal necrosis in the kidney was clearly greater in the present study and this finding might be explained by assuming that a sufficient number of free larvae within the snail would be necessary for the development of epithelial necrosis in the whole kidney.
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Baur, Bruno, José D. Gilgado e Armin Coray. "Prey handling and feeding habits of the snail predator Licinus depressus (Coleoptera, Carabidae)". Alpine Entomology 7 (4 luglio 2023): 63–68. http://dx.doi.org/10.3897/alpento.7.103164.
Testo completoAbstract (sommario):
Carabid beetles of the tribe Licinini use their asymmetric mandibles to open the shells of land snails. Prey handling of large snails has been described in a few Licinini species. We observed for the first time how a male of Licinus depressus (Paykull, 1790) opens the shells of small prey snails (Chondrina arcadica (Reinhardt, 1881)) and eats their soft bodies. The beetle holds the conical snail shell with its forelegs and breaks the wall of the right-hand coiled shell. In doing so, the beetle rotates the shell counter-clockwise opening it stepwise along the dorsal part of the whorls towards the apex. After some bites, the beetle interrupts the opening process and begins to feed on the snail’s soft tissue. Then the beetle continues to break up the shell, shortly after which there is another feeding phase. The alternating sequence of shell breaking and feeding ends after 2 to 2.5 whorls when the beetle can no longer hold the prey’s remaining intact shell. We compare this previously unknown way of prey handling with the reported predatory behaviour in large snails by other Licinini species. Our observations confirm the high plasticity of predatory behaviour in Licinini beetles.
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LEVRI, E. P., J. DILLARD e T. MARTIN. "Trematode infection correlates with shell shape and defence morphology in a freshwater snail". Parasitology 130, n. 6 (22 febbraio 2005): 699–708. http://dx.doi.org/10.1017/s0031182005007286.
Testo completoAbstract (sommario):
Parasitism often influences the phenotype of individuals. Many of the resulting changes are due to changes in resource allocation that come with infection. Here we examine the effect of a trematode parasite on the shape and defence morphology of a New Zealand freshwater snail, Potamopyrgus antipodarum. The trematode Microphallus sp. asexually produces hundreds of metacercarial cysts in the snail. The length, width and 2-dimensional area of each snail were measured. Snails were also assessed for their degree of spininess. Snails were dissected to determine gender, brooding condition and parasitism. Snails infected with Microphallus sp. were found to be significantly less spiny than uninfected snails. Microphallus-infected snails were also found to have a significantly greater width to length ratio at larger sizes than their uninfected counterparts. These trends could be explained in at least 3 ways. (1) Infection causes the snails to not produce spines and to become wider. (2) Spiny and narrower snails are more likely to die when they become infected. (3) Spiny and narrower snails are more resistant to infection. The changes in phenotype observed are unlikely to be adaptive for either the host or parasite and probably represent physiological by-products of the host-parasite relationship.
20
Rivera, E. R., e J. Jourdane. "Ultrastructure of transplanted schistosome sporocysts in incompatible snails". Proceedings, annual meeting, Electron Microscopy Society of America 49 (agosto 1991): 116–17. http://dx.doi.org/10.1017/s0424820100084880.
Testo completoAbstract (sommario):
The tropical parasitic disease schistosomiasis haematobium requires the snail vector Bulinus truncatus to successfully complete its life cycle. While in the snail, the parasite exists as a cercarial producing sporocyst. The infection of snails by the parasite is very specific, different subpopulations (strains) of parasites are not always compatible with snails from different geographic regions. It is not always known if the incompatibility is due to failure of penetration of snails by parasites or to subsequent destruction of sporocysts by infected snails. In these experiments, sporocysts from compatible sporocyst-snai1 infections were surgically transplanted into snails not compatible with the parasite.Egyptian snails (B. truncatus) which had been infected with the Egyptian strain of Schistosoma haematobium were dissected after five weeks. Sporocysts were removed from the hepatopancreas and surgically implanted into B. truncatus snails from Egypt (compatible), Morocco and Niger (incompatible). After four days, these snails were dissected and the transplanted sporocysts were prepared for electron microscopy. Each sample was also tested for glycogen contents by the Thiery Silver test.
21
Liu, Jian Tao, Zi Hao Deng, Jian Hua Huang, Ya Wang, Jun Chang e Du Zhu. "Apple Snails Polysaccharide Extraction and Pharmacological Potential Study In Vitro". Applied Mechanics and Materials 651-653 (settembre 2014): 207–10. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.207.
Testo completoAbstract (sommario):
Apple Snails is a snail-like animal. Being snail-like animals recognized as an edible aquatic animal and widely employed in traditional Chinese medicine, this study intends to reveal pharmacological potential of Apple Snails polysaccharide. Crude soluble polysaccharide of Apple Snails was first extracted using the hot water extraction and ethanol precipitation method. And the crude polysaccharide was purified successively using the Sevag method. After purification we found that and apple snails is rich in polysaccharide and the total polysaccharide content can reach to 68.4%. Using Fenton reactions, we found that antioxidant potential efficiency of apple snails polysaccharide is dose-dependent and can reach to 83.77% at the concentration of 5 mg/mL. Importantly, apple snails polysaccharide can efficiently inhibit lung cancer cell line A-549 proliferation in vitro and over 50% cell was killed in the dose of 200 mg/ml at 24 hours post treatment, implying that apple snails polysaccharide is a potential anti-tumor candidate.
22
Rondelaud, D., P. Vignoles e G. Dreyfuss. "The presence of predators modifies the larval development of Fasciola hepatica in surviving Lymnaea truncatula". Journal of Helminthology 76, n. 2 (giugno 2002): 175–78. http://dx.doi.org/10.1079/joh2001103.
Testo completoAbstract (sommario):
AbstractExperimental infections of Lymnaea truncatula with Fasciola hepatica were performed to study the consequences of the presence of predators (sciomyzid larvae or zonitid snails) on the characteristics of larval F. hepatica development in surviving snails. Controls consisted of infected snails that were not subjected to predators. Compared to controls, the survival rate at day 30 post-exposure, the duration of cercarial shedding, and the number of cercariae shed by surviving snails were significantly lower when predators were present in snail breeding boxes, whatever the type of predator used. In contrast, the prevalences of Fasciola infections in snails, and the length of time between exposure and the onset of cercarial shedding showed no significant variation. The progressive development of a stress reaction in surviving snails against predators during the first 30 days of experimental exposure to F. hepatica would influence snail survival during the cercarial shedding period and, consequently, the number of cercariae shed by the snails.
23
Hayashi, Masakazu, e Shinji Sugiura. "Shell-breaking predation on gastropods by Badister pictus (Coleoptera, Carabidae) with strikingly asymmetric mandibles". ZooKeys 1044 (16 giugno 2021): 815–30. http://dx.doi.org/10.3897/zookeys.1044.62293.
Testo completoAbstract (sommario):
The adults and larvae of some groups in the coleopteran family Carabidae are known to prey on snails (Mollusca: Gastropoda). Most species of the carabid tribe Licinini are believed to feed on live snails. However, the snail-eating behavior of only a few species has been studied. Whether adults of the licinine genus Badister can prey on live snails was tested by providing 155 live snails of 20 species (eleven terrestrial and nine aquatic species) to adults of Badister pictus Bates, 1873, and observing their behavior under laboratory conditions. Six of the 20 snail species have an operculum that can close the aperture of the shell. Each B. pictus adult attacked all of the snails provided. Badister pictus successfully preyed on ten terrestrial and six aquatic snail species. These beetles used their strikingly asymmetrical mandibles to break the dextral shells along the dorsal part of the whorls from the outer lip of the aperture towards the apex, allowing subsequent consumption of the soft bodies. However, 41.9% of snails could not be eaten by B. pictus adults. The rate of predation success by B. pictus decreased with increasing shell size and thickness of snails. In addition, the presence of an operculum decreased the rate of predation success by B. pictus. The results show that the shell size, thickness, and operculum of some snail species could play important roles in preventing B. pictus mandibles from breaking the shells. Therefore, Badister beetles may exert selective pressure on the evolution of defensive shell structures in small-sized snails.
24
Schallig, H. D. F. H., M. J. M. Sassen, P. L. Hordijk e M. De Jong-Brink. "Trichobilharzia ocellata: influence of infection on the fecundity of its intermediate snail host Lymnaea stagnalis and cercarial induction of the release of schistosomin, a snail neuropeptide antagonizing female gonadotropic hormones". Parasitology 102, n. 1 (febbraio 1991): 85–91. http://dx.doi.org/10.1017/s0031182000060376.
Testo completoAbstract (sommario):
SUMMARYSubadult and adult specimens of the pond snail Lymnaea stagnalis were infected with the schistosome Trichobilharzia ocellata. Egg production and growth of the snails were monitored over an 8-week period post-infection (p.i.). Snail haemolymph was collected and analysed for the presence of schistosomin, a neuropeptide which antagonizes the action of the snails' female gonadotropic hormones. Snails infected as subadults showed an increase in fecundity during the first 4 weeks p.i. compared with non-infected controls. The possibility is discussed that this increase is caused by an accelerated maturation of the female sex organs due to elevated levels of Dorsal Body Hormone, a female gonadotropic hormone. No difference in fecundity was found between snails infected as adults and control snails during the first 4 weeks p.i. Snails infected as subadults and as adults showed a decrease in fecundity from week 5 p.i. and onwards. This decrease coincided with the appearance of schistosomin in the haemolymph of the snails and with that of differentiating cercariae in the daughter sporocysts. Cercariae are probably involved in the induction of schistosomin release from the snails' CNS into the haemolymph. Snails infected as subadults or as adults grew at approximately the same rate as uninfected snails.
25
Ismail, Hassan A. H. A., Abed el Aziz A. el R. M. Ahmed, Young-Ha Lee, Mousab Siddig Elhag, Youngjin Kim, Seungman Cha e Yan Jin. "Population Dynamics of Intermediate-Host Snails in the White Nile River, Sudan: A Year-Round Observational Descriptive Study". Korean Journal of Parasitology 59, n. 2 (22 aprile 2021): 121–29. http://dx.doi.org/10.3347/kjp.2021.59.2.121.
Testo completoAbstract (sommario):
We aimed to explore the population dynamics of snail in 3 sites of the White Nile in Sudan. More specifically, we aimed to investigate the annual patterns of snail populations that act as intermediate hosts of schistosomes and monthly snail infection rates and ecological characteristics presumably related to snail populations. We collected snails for 1 year monthly at 3 different shore sites in the vicinity of El Shajara along the White Nile river in Khartoum State, Sudan. In addition, we measured air and water temperatures, water turbidities, vegetation coverages, and water depths and current speeds. Most of the collected snails were <i>Biomphalaria pfeifferi</i> and <i>Bulinus truncatus</i>. The population densities of snails and their infection rates varied across survey sites. The collected snails liberated <i>S. mansoni</i> and <i>S. haematobium</i> cercariae as well as Amphistome and Echinostome cercariae. Infected snails were found during March-June. The ecological characteristics found to be associated with the absence of snails population were: high turbidity, deep water, low vegetation coverage (near absence of vegetation), high water temperature, and high current speed. To our knowledge, this is the first longitudinal study of the snail population and ecological characteristics in the main basin of the White Nile river.
26
Ziomek, Monika, Krzysztof Szkucik, Monika Maćkowiak-Dryka, Waldemar Paszkiewicz, Łukasz Drozd e Renata Pyz-Łukasik. "Veterinary regulations for obtaining and processing edible snails". Medycyna Weterynaryjna 73, n. 12 (2017): 819–25. http://dx.doi.org/10.21521/mw.5796.
Testo completoAbstract (sommario):
For many years Poland has been a highly recognized producer and supplier of Cornu aspersum (Cornu aspersum aspersum, Cornu aspersum maxima) and Helix pomatia snails in European markets. Exports include both live snails and snail-derived food products such as snail meat and eggs. Slime, used in pharmaceutical and cosmetic industries, is another economically significant snail-derived product. This paper presents standardized terminology for farm snails and outlines regulations concerning snail farming, trade, processing plants and snail meat obtained. The current results of microbiological studies of snail meat obtained in Poland are shown as well. The analysis conducted in this paper indicates the need to clarify legislation, especially with regard to snail farming, and to elaborate regulations on snail meat processing....
27
Manalo, Daria L., Jude Karlo G. Bolivar, Paul Raymund Yap, Ma Ricci R. Gomez, Zaldy P. Saldo, Mark Joseph M. Espino, Joselito E. Dilig et al. "From Perpetual Wetness to Soil Chemistry: Enumerating Environmental and Physicochemical Factors Favoring Oncomelania hupensis quadrasi Snail Presence in the Municipality of Gonzaga, Cagayan, Philippines". Tropical Medicine and Infectious Disease 9, n. 1 (29 dicembre 2023): 9. http://dx.doi.org/10.3390/tropicalmed9010009.
Testo completoAbstract (sommario):
Snail control to complement mass drug administration is being promoted by the World Health Organization for schistosomiasis control. Oncomelania hupensis quadrasi, the snail intermediate host of Schistosoma japonicum in the Philippines, has a very focal distribution; thus, scrutinizing baseline data and parameters affecting this distribution is very crucial. In this study in Gonzaga, Cagayan, Philippines, snail habitats were surveyed, and the various factors affecting the existence of the snails were determined. Malacological surveys and the mapping of sites of perpetual wetness in five endemic and five neighboring non-endemic barangays were conducted. Environmental and physicochemical factors were also examined. Maps of both snail and non-snail sites were generated. Of the fifty sites surveyed, O. h. quadrasi were found in twelve sites, and two sites yielded snails that were infected with S. japonicum cercariae. Factors such as silty loam soil, proximity to a snail site, water ammonia, and soil attributes (organic matter, iron, and pH) are all significantly associated with the presence of snails. In contrast, types of habitats, temperatures, and soil aggregation have no established association with the existence of snails. Mapping snail sites and determining factors favoring snail presence are vital to eliminating snails. These approaches will significantly maximize control impact and minimize wasted efforts and resources, especially in resource-limited schistosomiasis endemic areas.
28
Rondelaud, D., e G. Dreyfuss. "Variability of Fasciola infections in Lymnaea truncatula as a function of snail generation and snail activity". Journal of Helminthology 71, n. 2 (giugno 1997): 161–66. http://dx.doi.org/10.1017/s0022149x00015844.
Testo completoAbstract (sommario):
AbstractField investigations were carried out over a 4-year period in three farms of the Haute-Vienne department (France) in order to determine the prevalence of Fasciola hepatica infection in the annual generations of Lymnaea truncatula. Infection rates found in March were significantly lower than those recorded in July or in September (0.8% to 2.2% compared to 5.7% to 13.5% and 4.4% to 9.3%, respectively). They were always lower in overwintering snails than in other snail generations (summer generation in 1989,1990 and 1991; spring and summer generations in 1992). Experimental infections of L. truncatula by F. hepatica were performed to evaluate the characteristics of Fasciola infection with reference to snail generation and snail activity. Survival of summer generation snails at day 30 postexposure was significantly lower in snails collected in September than in those collected in May and June. In the winter generation of L. truncatula, snail survival was significantly higher in snails collected from December to March than in those from November. The prevalence of infection was significantly lower in snails collected in September (summer generation) than in those collected from December to March (winter generation). The duration of the prepatent period was significantly delayed in snails collected from January to March (a mean of 54.2 to 58.2 days instead of 43.1 to 49 days in the other groups), whereas that of the patent period was significantly shorter (5 to 9.3 days instead of 18.3 to 40.3 days, respectively). In snails collected from January to March, the number of metacercariae was significantly lower than that found from other snail groups (a mean of 21.5 to 42 metacercariae instead of 72.8 to 151.4 cysts, respectively). Fasciola infections of L. truncatula originating from spring and summer generations were more efficient than those from the winter generation of snails.
29
Skorping, Arne. "Parasite–induced reduction in host survival and fecundity: the effect of the nematode Elaphostrongylus rangiferi on the snail intermediate host". Parasitology 91, n. 3 (dicembre 1985): 555–62. http://dx.doi.org/10.1017/s003118200006279x.
Testo completoAbstract (sommario):
SUMMARYThe effect of the protostrongylid nematode, Elaphostrongylus rangiferi, on the fecundity and survival of an intermediate snail host, Arianta arbustorum, was studied. Over an experimental period of 12 weeks, infected snails had a significantly lower egg production than uninfected control snails. No significant difference in survival was found between infected and uninfected adult snails. Infected juvenile snails showed a consistent decrease in survival with increasing mean density of parasites. A linear relationship was found between snail instantaneous death rate over a 28–day interval and the mean number of parasites/snail. When calculated for 4–day intervals, the instantaneous death rate was highest between 8 and 12 days post–infection. It is concluded that the most pathogenic phase of this parasite is during the first moult.
30
Riley, Leslie, Mark Dybdahl e Robert Hall. "Fertilization of Algal Resources By an Exotic Snail May Facilitate Invasion". UW National Parks Service Research Station Annual Reports 27 (1 gennaio 2003): 116–22. http://dx.doi.org/10.13001/uwnpsrc.2003.3555.
Testo completoAbstract (sommario):
We studied positive and negative effects of snail consumers on their resource to determine if positive consumer effects may be facilitating invasion. Consumer- resource interactions often focus on losses to the resource, even though the resource might benefit if consumers recycle nutrients. The New Zealand mudsnail, Potamopyrgus antipodarum, an exotic in western U.S. rivers, attains high densities and dominates macroinvertebrate communities. In one well-studied river, it consumes the majority of primary productivity, cycles most nitrogen and can grow faster at higher densities. In field experiments, we tested the hypothesis that this invasive grazer stimulates algal growth via nitrogen excretion, which might explain its self-facilitation and invasiveness. Using in-stream cages subdivided into "with snails" and "without snails" sections, we examined the response of periphytic algae to snail grazing and excretion and snail excretion alone at various levels of snail biomass. We found that chlorophyll a and GPP (gross primary production) decreased as the biomass of snails increased in the grazed sections. Snail excretion, in the absence of grazing, increased both chlorophyll a and GPP, demonstrating a positive effect of snails on the resource, consistent with the nutrient recycling and enrichment hypothesis. We found no evidence for increased algal growth at intermediate snail densities in grazed treatments, as predicted by the Herbivore Optimization Curve hypothesis. However, the difference in chlorophyll a between "with snails" and "without snails" treatments increased as snail biomass increased. This suggests that snail compensation of the resource, through excretion, decreases at extremely high levels of grazing pressure and the net effect of snail grazing becomes negative. Together, these results suggest that invasiveness in some rivers may be fostered by this self-facilitation and recycling of essential nutrients.
31
Bachtel, Rebecca Z., Matthew Rittenhouse, Gregory J. Sandland e Jennifer A. H. Koop. "Infection patterns of trematodes across size classes of an invasive snail species using field and laboratory studies". Parasitology 146, n. 4 (27 settembre 2018): 438–44. http://dx.doi.org/10.1017/s0031182018001646.
Testo completoAbstract (sommario):
AbstractIn the Upper Mississippi River Region, invasive faucet snails (Bithynia tentaculata) and their trematode parasites have been implicated in more than 182 000 waterfowl deaths since 1996. Estimating transmission potential depends on accurate assessments of susceptible host population size. However, little is known about the mechanisms underlying snail–host susceptibility in this system. Prior field studies suggest that very small, likely young, faucet snails are less suitable secondary intermediate hosts. Here, we test whether the patterns observed in the field are because small snails (1) are refractory to infection by cercariae, (2) die from infection and are removed from sampled populations, and/or (3) are not preferred by cercariae. Our own field collections were consistent with the observation that smaller faucet snails exhibit lower metacercarial infection prevalence and abundance than larger snails. However, laboratory-based experiments show that smaller snails were actually more susceptible to infection than larger snails. Moreover, the smallest snail size class had significantly higher mortality than larger snails following infection, which may explain their reduced infection levels observed in the field. Our study demonstrates the importance of pairing field and laboratory studies to better understand mechanisms underlying patterns of infection.
32
Charrier, Maryvonne, Yannick Combet-Blanc e Bernard Ollivier. "Bacterial flora in the gut ofHelix aspersa(Gastropoda Pulmonata): evidence for a permanent population with a dominant homolactic intestinal bacterium,Enterococcus casseliflavus". Canadian Journal of Microbiology 44, n. 1 (1 gennaio 1998): 20–27. http://dx.doi.org/10.1139/w97-120.
Testo completoAbstract (sommario):
We previously demonstrated the existence of bacteria degrading carboxy-methyl-cellulose in the gut of the phytophagous snail Helix aspersa and found Enterobacteriaceae predominating in the intestine of snails dissected in aerobic conditions. Here, we investigated the effects of several nutritional treatments on the snail's microflora. Food sterilization led to increased snail growth and reduced cellulase activity in the crop, suggesting a noxious effect of microbial exogenous cellulases. A second aim of this study was to look for anaerobic bacteria. No strict anaerobic cellulolytic, homoacetogenic, or methanogenic bacteria were enriched from the gut. However, a motile Gram-positive homolactic coccobacillus, grown in anaerobic conditions, dominated in the snail's intestine (1.57 x 109± 0.10 x 109cells.g-1intestine). It was identified as Enterococcus casseliflavus. Its occurrence in the intestine of H. aspersa is discussed with regard to the snail's digestive processes and the presence of a fecal mucous ribbon. A possible snail-bacterium synergistic action is suggested.Key words: snail, Helix aspersa, gut, Enterococcus casseliflavus, fermentative homolactic bacterium, antibiotics.
33
Eliuk, L. K., S. Brown, R. C. Wyeth e J. T. Detwiler. "Parasite-modified behaviour in non-trophic transmission: trematode parasitism increases the attraction between snail intermediate hosts". Canadian Journal of Zoology 98, n. 7 (luglio 2020): 417–24. http://dx.doi.org/10.1139/cjz-2019-0251.
Testo completoAbstract (sommario):
Many parasites with complex life cycles cause host behavioural changes that increase the likelihood of transmission to the next host. Parasite modification is often found in trophic transmission, but its influence on non-trophic transmission is unclear. In trematodes, transmission from the first to second intermediate host is non-trophic, suggesting that free-swimming larvae (cercariae) emerging in closer proximity to the next host would have higher transmission success. We performed a series of behavioural experiments with echinostome trematodes and their snail hosts to determine if potential second hosts (ramshorn snail, genus Planorbella Haldeman, 1842) were more attracted to parasitized first hosts (marsh pondsnail, Lymnaea elodes Say, 1821). In a Y maze, a responding snail (Planorbella sp.) was placed in the base and its response to five treatments was assessed: no stimulus, turion duckweed (Lemna turionifera Landolt; a food item), non-parasitized L. elodes, parasitized L. elodes, and finally parasitized versus non-parasitized L. elodes. Snails showed some attraction to uninfected snails, but had a stronger response to infected first host snails. These results indicate that potential second host snails were more attracted to parasitized, heterospecific first host snails over non-parasitized heterospecific snails. This study demonstrates that echinostome trematodes alter snail behaviour by changing navigational choices in uninfected potential hosts through a chemical communication mechanism.
34
Igbinosa, I. B., C. Isaac, H. O. Adamu e G. Adeleke. "Parasites of edible land snails in Edo State, Nigeria". Helminthologia 53, n. 4 (1 dicembre 2016): 331–35. http://dx.doi.org/10.1515/helmin-2016-0031.
Testo completoAbstract (sommario):
Summary Land snails are sources of protein to man and are hosts to a number of parasites. It is imperative that the roles of the snail hosts and parasites are clearly defined. Before then however, the parasites of the different land snails collected in any locality should be identified. Land snails were collected in the wild in both dry and wet seasons. The internal organs and the faeces were examined for the presence of parasite. In the rainy season of 2015, a total of 272 snails were collected across four major towns (Benin, Uromi, Ekpoma and Auchi) in Edo State, Nigeria, while in the dry season, fewer snails (n=91) were handpicked. The snail species seen are: Achatina achatina (Linnaeus, 1758), Achatina fulica (Férussac, 1821), Acharchatina marginata (Swainson, 1982), Limicolaria aurora (Jay, 1839), L. flammea (Müller, 1774) and Limicolariopsis spp. The larvae of Strongyloides stercoralis were isolated from the various snail species with overall prevalence of 54.04 %. Snails positive with Alaria mesocercariae were L. aurora, L. flammea and Limicolariopsis spp. Additionally, few L. flammea were positive of the cercariae of Drocoelium dedriticum. Meanwhile, some samples of A. fulica harboured larvae of Angiostrongylus cantonesis, sporocysts of Fasciola gigantica and Schistosoma mansoni. Therefore, these edible snails could pose serious health hazard to man and animals by serving as a possible alternative parasite transmission route.
35
Meyer III, Wallace M., Kenneth A. Hayes, Norine W. Yeung, Edward J. Crane III, Alexandra Turvey, Claire LeBlanc e Andre R. O. Cavalcanti. "The trail less traveled: Envisioning a new approach to identifying key food resources for threatened Hawaiian arboreal snails". Nature Conservation 51 (10 febbraio 2023): 137–53. http://dx.doi.org/10.3897/natureconservation.51.94952.
Testo completoAbstract (sommario):
Our understanding of Hawaiian arboreal snails’ diets remains rudimentary, hindering the development of effective conservation strategies. To identify important food resources, we tested the hypothesis that epiphytic microbial assemblages differ on plant species preferred and avoided by snails at Mt. Kaala Natural Area Reserve, where snail plant preferences are known from previous studies. Comparing microbial assemblages on plants that snails both prefer and avoid was identified as a potentially key step to moving research away from characterizing which microbes snails encounter, towards testing if microbial assemblages are driving snail plant preferences. We found that fungal and bacterial assemblages differed between plant species preferred and avoided by snails, indicating that Hawaiian arboreal snails may be selecting plants based on their epiphytic microbial assemblages. Previous microbes thought to be important, Cladosporium spp., propagated in captive rearing facilities, and Botryosphaeria spp., preferred fungi in a feeding experiment, were both rare and had similar abundances on preferred and avoided plant species in Mt. Kaala. Our approach, conducting preference studies before isolating microbes, is key to identifying arboreal snail food resources and improves our ability to identify microbes that form the foundation of Hawaiian arboreal snails’ diet. If we can identify important food resources, it greatly expands our ability to: (1) assess and monitor habitat quality, (2) make informed restoration recommendations, and (3) improve rearing efforts for highly endangered captive reared populations.
36
WANI, Z. A., R. A. SHAHARDAR, K. H. BULBUL, I. M. ALLAIE e AIMAN ASHRAF. "Seasonal dynamics of freshwater gastropods in central zone of Kashmir Valley, India". Indian Journal of Animal Sciences 94, n. 1 (9 gennaio 2024): 17–25. http://dx.doi.org/10.56093/ijans.v94.i1.123052.
Testo completoAbstract (sommario):
The present study was carried out to study the prevalence and seasonal distribution of snail fauna in central zone of Kashmir valley. A total of 12,103 snails were collected during September 2017 to August 2018 and 10 snail species under 5 genera recorded were Physa acuta, Lymnaea lagotis f. costulata, L. stagnalis, L. brevicauda, auricularia var obliquata, L. luteola f. typica, Gyraulus ladacensis, G. pankogensis, Bithynia troscheli and Indoplanorbis exustus. Besides this, one unidentified snail was also reported. Species-wise overall prevalence was observed highest for P. acuta (18.65%), followed by L. lagotis (15.54%), L. stagnalis (13.31%), G. ladacensis (11.49%), L. brevicauda (10.19%), B. troscheli (8.00%), L. auricularia (6.94%), I. exustus (5.32%), L. luteola (5.15%), G. pankogensis (3.42%) and lowest for unidentified snail (1.94%). Prevalence of snails was found to be highest in summer (53.81%) followed by spring (29.76%), autumn (15.66%) and lowest in winter season (0.75%), the difference being statistically significant between seasons. Overall F% and RF% of snails was observed to be highest for P. acuta followed by Lymnaea spp. other than L. stagnalis, Gyraulus spp., B. troscheli, I. exustus and lowest for unidentified snail. Overall F% and RF% of snails was also observed highest in summer followed by spring, autumn and lowest in winter season. Based on RF%, all snails were found highly distributed, except for unidentified snail, which was found to be lightly distributed. The study concluded that Physa snails were found highly prevalent. Knowledge of the particular snail and cercariae released by them could be used to formulate control strategy to reduce the burden of trematode parasites in animals. Unidentified snail recorded in this study appears to be new species, which needs further detailed investigation.
37
Baker, G. H. "The population dynamics of the mediterranean snails Cernuella virgata, Cochlicella acuta (Hygromiidae) and Theba pisana (Helicidae) in pasture - cereal rotations in South Australia: a 20-year study". Australian Journal of Experimental Agriculture 48, n. 12 (2008): 1514. http://dx.doi.org/10.1071/ea08031.
Testo completoAbstract (sommario):
The snails Cernuella virgata, Cochlicella acuta and Theba pisana are introduced pests of grain crops and pastures in southern Australia. The population dynamics of these three species of snail were studied for 20 years in two adjacent fields where they coexisted on a farm on the Yorke Peninsula in South Australia. The fields were used for pasture–cereal rotations. Surveys were conducted in autumn and spring each year, coinciding respectively with the start of the breeding season and peak abundance of snails (mostly juveniles). Populations varied greatly in abundance between years and between species, but snails were generally most common in spring, in wet years, especially those with wet autumns and wet springs. Rainfall early in a particular year (i.e. at sowing of crops in autumn) can thus be used to predict the likelihood of heavy snail infestations later in spring (i.e. at harvest). In contrast, the abundance of adult snails in autumn was a poor predictor of the subsequent abundance of juvenile snails in spring, especially in crops. There were no significant correlations, at field scale, between the average abundance of the three species of snail in spring, in either pastures or crops. However, at a sampling scale of 0.25 m2, there were consistent, negative relationships between the abundance of all three snail species. Such patterns may reflect either competitive interactions between snails or subtle differences in micro-habitat choice. Patterns in the abundance of snails (e.g. large numbers near field edges) were suggestive of occasional invasion from dense populations in adjacent fields.
38
MAKARYNSKA, A. V., L. M. YARMAK e O. M. PIDDUBNYAK. "SCIENTIFIC AND TECHNOLOGICAL SUBSTANTIATION OF PRODUCTION OF MIXED FODDERS FOR SNAILS". Grain Products and Mixed Fodder’s 18, n. 4 (17 gennaio 2019): 39–46. http://dx.doi.org/10.15673/gpmf.v18i4.1196.
Testo completoAbstract (sommario):
The article deals with the issues of modern snail breeding in Ukraine, problems and prospects for their cultivation. The main areas of use of snails are classified. With the proper cultivation of snails, the business is profitable, because meat and slime of snails are expensive, have a lot of useful qualities. The characteristic of the farms for the production of snails in Ukraine and the products of snails - snails, meat, caviar, mucus. The volumes and methods of growing snails in the world and Ukraine have been analyzed, the tendency of annual increase in livestock and consumption of snails, especially in Europe, is formed, which creates favorable market conditions that guarantee the constant demand for products of activity of snail farms in Ukraine. It was established that in 2018 volumes reached 750 thousand tons. The data of the main countries of producers, importers and consumers of snails in the world are presented. The advantages and disadvantages of the production of snails are determined in comparison with the cultivation of farm animals. The analysis and characterization of feed supplementation for Ahatinka snails and grain-calcium blend used in Ukraine is provided. Objects of research - Snails Akhaten and snails grape Helix pomatia, fodder for snails. Scientifically substantiated and calculated recipe of full-feed compound for snails using the software complex KormOptimaExpert, which includes grain, protein mineral components and biologically active substances. The step-by-step scheme of technology of production of mixed fodders for snails is indicated, indicating technological regimes of production, according to which experimental samples of mixed fodder are made. The physical, chemical and microbiological indices of full-fodder mixed fodders for the snails were studied. According to the organoleptic, physical properties and chemical composition, ready-mixed fodder for snails meets the requirements of the State Standard of Ukraine. The results of the zootechnical evaluation of the developed mixed fodder, according to which it was established that feed for snails during feeding gives a positive zootechnical effect, since the size of the shell at the end of the experiment relates to the commodity, the increase in the mass of snails increased by 13.6%, and the length by 30% at the coefficient the usefulness of a feed is equal to 1,2 ... 1,5.
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Mereta, Seid Tiku, Samson Wakuma Abaya, Fikirte Demissie Tulu, Kebede Takele, Mahmud Ahmednur, Girma Alemu Melka, Mark Nanyingi et al. "Effects of Land-Use and Environmental Factors on Snail Distribution and Trematode Infection in Ethiopia". Tropical Medicine and Infectious Disease 8, n. 3 (1 marzo 2023): 154. http://dx.doi.org/10.3390/tropicalmed8030154.
Testo completoAbstract (sommario):
Freshwater snails are intermediate hosts for several snail-borne diseases affecting humans and animals. Understanding the distribution of snail intermediate hosts and their infection status is very important to plan and implement effective disease prevention and control interventions. In this study, we determined the abundance, distribution, and trematode infection status of freshwater snails in two agro-ecological zones of Ethiopia. We sampled snails from 13 observation sites and examined them for trematode infections using a natural cercarial shedding method. A redundancy analysis (RDA) was used to examine the relationship between snail abundance and environmental variables. Overall, a total of 615 snails belonging to three species were identified. Lymnea natalensis and Bulinus globosus were the dominant snail species, representing 41% and 40% of the total collection, respectively. About one-third of the total snail population (33%) shed cercariae. The cercariae species recorded were Xiphidiocercaria, Brevifurcate apharyngeate distome (BAD), Echinostome, and Fasciola. Snail species were found in high abundance in aquatic habitats located in the agricultural landscape. Therefore, land-use planning and protection of aquatic habitats from uncontrolled human activities and pollution can be considered as important strategies to prevent and control the spread of snail-borne diseases in the region.
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Ebou, Anicet, Dominique Koua, Audrey Addablah, Solange Kakou-Ngazoa e Sébastien Dutertre. "Combined Proteotranscriptomic-Based Strategy to Discover Novel Antimicrobial Peptides from Cone Snails". Biomedicines 9, n. 4 (29 marzo 2021): 344. http://dx.doi.org/10.3390/biomedicines9040344.
Testo completoAbstract (sommario):
Despite their impressive diversity and already broad therapeutic applications, cone snail venoms have received less attention as a natural source in the investigation of antimicrobial peptides than other venomous animals such as scorpions, spiders, or snakes. Cone snails are among the largest genera (Conus sp.) of marine invertebrates, with more than seven hundred species described to date. These predatory mollusks use their sophisticated venom apparatus to capture prey or defend themselves. In-depth studies of these venoms have unraveled many biologically active peptides with pharmacological properties of interest in the field of pain management, the treatment of epilepsy, neurodegenerative diseases, and cardiac ischemia. Considering sequencing efficiency and affordability, cone snail venom gland transcriptome analyses could allow the discovery of new, promising antimicrobial peptides. We first present here the need for novel compounds like antimicrobial peptides as a viable alternative to conventional antibiotics. Secondly, we review the current knowledge on cone snails as a source of antimicrobial peptides. Then, we present the current state of the art in analytical methods applied to crude or milked venom followed by how antibacterial activity assay can be implemented for fostering cone snail antimicrobial peptides studies. We also propose a new innovative profile Hidden Markov model-based approach to annotate full venom gland transcriptomes and speed up the discovery of potentially active peptides from cone snails.
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Syafitri, Vika Annur, Zubaidah Anjar Rezeki e Azwin Apriandi. "LAJU KEMUNDURAN MUTU GONGGONG (Strombus sp.) REBUS PADA PENYIMPANAN SUHU CHILLING DAN RUANG DENGAN MUTU SENSORI". Marinade 3, n. 02 (31 ottobre 2020): 139–47. http://dx.doi.org/10.31629/marinade.v3i02.3402.
Testo completoAbstract (sommario):
This research was conducted to observe the rate of deterioration in the quality of
boiled snails (Strombus sp.). Organoleptic is a method of sensory freshness determination. The
speed at which a snail decomposed was primarily influenced by the temperature. This study
aims to determine the best quality of barking snails stored at chilling and rooming temperatures.
Samples of barking snails were taken from Tanjung Unggat water. This research method
includes measuring the morphometric, yield, and organoleptic of the barking snail (Strombus
sp.). The results showed that the use of chilling temperature could extend the shelf life of boiled
barking snails, as evidenced by the high value of the organoleptic parameters compared to
barking snails at room temperature storage, based on the organoleptic parameters of frozen
clam meat based on SNI 3460.1-2009.
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Levri, Edward P., Andrea N. Dubensky, Ashley S. Mears e Carol A. Opiela. "Interpopulation variation in predator avoidance behavior of a freshwater snail to the same predator". Canadian Journal of Zoology 90, n. 5 (maggio 2012): 616–23. http://dx.doi.org/10.1139/z2012-027.
Testo completoAbstract (sommario):
The New Zealand mud snail ( Potamopyrgus antipodarum (J.E. Grey, 1843)) responds to the presence of predatory fish by moving to a safer environment. These experiments attempted to determine if predator detection by the snail results in specific responses to light and (or) gravity by the snail and if snails respond more or less to fish from their native lake compared with fish from a foreign lake. Snails and fish (Gobiomorphus cotidianus McDowall, 1975) were collected from lakes Alexandrina and Peorua from the South Island of New Zealand. Snails were placed in behavioral chambers and tested for their responses to the direction of light, vertical orientation with respect to gravity, and rate of movement in light and dark conditions. Snails from each lake were exposed to one of three treatments: plain water, water from fish from Lake Alexandrina, and water from fish from Lake Peorua. Results showed no effect of direction of light on behavior. Snails from Lake Alexandrina were not found to alter their up or down movements in response to the detection of fish. However, snails from Lake Peorua moved down more in response to fish from their own lake than fish from Lake Alexandrina or no fish. Both snail populations increase their speed in the light more when detecting Alexandrina fish compared with Peorua fish and no fish. Both snail populations show some evidence of enhanced response to local predator populations. Interestingly, different behavioral mechanisms appear to be responsible for the avoidance behaviors in each population.
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Li, Yinlong, Suying Guo, Hui Dang, Lijuan Zhang, Jing Xu e Shizhu Li. "Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions". Tropical Medicine and Infectious Disease 8, n. 5 (23 aprile 2023): 242. http://dx.doi.org/10.3390/tropicalmed8050242.
Testo completoAbstract (sommario):
The goal of schistosomiasis prevention and control in China is shifting from transmission interruption to elimination. However, the area inhabited by the intermediate host, the snail Oncomelania hupensis, has not changed much in recent years. Different environmental types have different impacts on snail breeding, and understanding these differences is conducive to improving the efficiency of snail monitoring and control and to saving resources. Based on previous epidemiological data, we selected 199 villages in 2020 and 269 villages in 2021 from transmission control, transmission interruption, and elimination areas of snail breeding. Snail surveys were conducted in selected villages using systematic sampling and/or environmental sampling methods in six types of snail-breeding environments (canals, ponds, paddy fields, dry lands, bottomlands, and undefined environments). All live snails collected from the field were evaluated for Schistosoma japonicum infection using the microscopic dissection method, and a subsample of snails was subjected to loop-mediated isothermal amplification (LAMP) to assess the presence of S. japonicum infection. Snail distribution data and infection rate and nucleic acid positive rate of schistosomes in snails were calculated and analyzed. The 2-year survey covered 29,493 ha of the environment, in which 12,313 ha of snail habitats were detected. In total, 51.16 ha of new snail habitats and 107.76 ha of re-emergent snail habitats were identified during the survey. The occurrence rate of snails in canals (10.04%, 95% CI: 9.88–10.20%) and undefined environments (20.66%, 95% CI: 19.64–21.67%) was relatively high in 2020, and the density of snails in bottomlands (0.39, 95% CI: 0.28–0.50) and undefined environments (0.43, 95% CI: 0.14–1.60) was relatively high in 2021. Of the 227,355 live snails collected in this study, none were S. japonicum-positive as determined by microscopy. Of the 20,131 pooled samples, however, 5 were S. japonicum-positive based on LAMP analysis, and they were distributed in three environmental types: 3 in bottomland, 1 in dry land, and 1 in a canal. The bottomland environment has a high risk of schistosomiasis transmission because it contains a large area of newly emerging and re-emerging snail habitats, and it also had the most breeding snails infected with S. japonicum. Thus, this habitat type should be the key target for snail monitoring and early warning and for the prevention and control of schistosomiasis.
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Herdiawan, Boni, Putri Afin Nurhayati e Galuh Ayu Chantika Dwitara. "Inventory of Land Snail in Darungan Lake, Bromo Tengger Semeru National Park 2019". Jurnal Biota 6, n. 1 (30 maggio 2020): 42–44. http://dx.doi.org/10.19109/biota.v6i1.5219.
Testo completoAbstract (sommario):
This study aims to determine the diversity of land snails that have never been revealed before. The location of this research is in the forest in the Ranu Darungan Resort area of Bromo Tengger Semeru National Park. The method used in this study is the 1.5 km transect line method. Land snails are often found behind leaves, around tree roots, and around leaf litter. The results of this study obtained 20 species of land snails, each of which has different characteristics. Land snail identification is using a land snail identification book. The lack of information about land snails in the Ranu Darungan Resort area makes this research expected to be the basis for further research.
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Hayashi, Masakazu, e Shinji Sugiura. "Climbing rice plants above the waterline: escape of freshwater snails from underwater predation by snail-eating specialists". Biological Journal of the Linnean Society 130, n. 4 (29 giugno 2020): 751–55. http://dx.doi.org/10.1093/biolinnean/blaa087.
Testo completoAbstract (sommario):
Abstract Freshwater molluscs have physical defences such as shells to protect their inner soft bodies from underwater predators. However, some predators have specialized mouthparts that can destroy the snail’s tough and/or spiral shells. Therefore, these snails could have evolved specific defences against their specialist predators. We observed the freshwater snail Austropeplea ollula (Pulmonata: Lymnaeidae) frequently climbing rice plants above the water in paddy fields in Shimane, central Japan. We also found the beetle larvae of Hydrophilus acuminatus (Coleoptera: Hydrophilidae), which are known as snail-eating specialists, in waters of the same paddy fields. We hypothesized that A. ollula climbs rice plants above the water to escape underwater predation by H. acuminatus and that the escape behaviour of snails may be specifically triggered by chemical cues from snail-eating specialists and/or killed conspecifics. To test both these hypotheses, we conducted laboratory experiments. The results demonstrated that chemical cues (e.g. body fluids) from killed conspecifics could trigger A. ollula to crawl above the waterline. Furthermore, chemical cues (e.g. scent and digestive enzymes) from H. acuminatus could promote the behaviour. Therefore, A. ollula can successfully escape from H. acuminatus by climbing the rice plants above the water.
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Rondelaud, D., F. F. Djuikwo Teukeng, P. Vignoles e G. Dreyfuss. "Lymnaea glabra: progressive increase in susceptibility to Fasciola hepatica through successive generations of experimentally infected snails". Journal of Helminthology 89, n. 4 (16 aprile 2014): 398–403. http://dx.doi.org/10.1017/s0022149x14000169.
Testo completoAbstract (sommario):
AbstractExperimental infections of Lymnaea glabra (two populations) with Fasciola hepatica were carried out during seven successive snail generations, to determine if prevalence and intensity of snail infection increased over time through descendants of snails already infected with F. hepatica. Controls were descendants coming from uninfected parents and infected according to the same protocol. No larval forms were found in the bodies of control snails coming from uninfected parents. In contrast, prevalence and intensity of F. hepatica infection in snails originating from infected parents progressively increased from the F2 or F3 to the F6 generation of L. glabra. In another experiment carried out with the F7 generations of L. glabra and a single generation of Galba truncatula (as controls), the prevalence of F. hepatica infection and the total number of cercariae were lower in L. glabra (without significant differences between both populations). If the number of cercariae shed by infected snails was compared to overall cercarial production noted in snails containing cercariae but dying without emission, the percentage was greater in G. truncatula (69% instead of 52–54% in L. glabra). Even if most characteristics of F. hepatica infection were lower in L. glabra, prevalence and intensity of parasite infection increased with snail generation when tested snails came from infected parents. This mode of snail infection with F. hepatica suggests an explanation for cases of fasciolosis occurring in cattle-breeding farms where paramphistomosis is lacking and G. truncatula is absent.
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Paul, Pranesh, Koushik Paul, Rupsha Karmakar, Arnab Shee, Debaditya Kumar e Gautam Aditya. "The exotic gastropod Clea helena (von dem Busch, 1847) as a predator of freshwater gastropods: a threat to native biota in India?" Limnological Review 21, n. 1 (1 marzo 2021): 55–62. http://dx.doi.org/10.2478/limre-2021-0005.
Testo completoAbstract (sommario):
Abstract The carnivorous snail Clea (Anentome) helena (von dem Busch, 1847) (Gastropoda: Nassariidae), commonly called as the “assassin snail” is sold worldwide including India for aesthetics and the ability to kill pest snails in aquaria. Assuming invasion as a fair possibility, the predation potential of C. helena on seven native freshwater snails was assessed. The exotic predator consumed all the native snail species provided in the experiment and prey consumption varied with the prey species identity, the prey density and the prey size class. Future colonization and establishment of C. helena in Indian freshwater ecosystems may reduce the abundance of the native gastropod snails, in absence of suitable intervention.
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Jabal, Arif Rahman, D. Mutiasari, H. Akbar, M. Arfah, M. Marhani, R. Rini, N. Sobak, A. J. Pisu, A. I. Toemon e A. Ratnasari. "Type of cercaria in freshwater snails at Tunggu Pampang Reservoir, Makassar City, Indonesia". Russian Journal of Infection and Immunity 12, n. 4 (9 settembre 2022): 765–71. http://dx.doi.org/10.15789/2220-7619-tci-1700.
Testo completoAbstract (sommario):
The Tunggu Pampang Reservoir is one of the reservoirs located in the city of Makassar. The functions of the reservoir area was tourist attractions and fish farming locations so that the local community uses them for swimming, fishing, selling, and gardening. The existence of various types of freshwater snails in the reservoir has the potential to act as intermediate hosts for trematodes in animals and humans. This study aimed to analyze the type of cercariae in freshwater snails. This research is a descriptive survey to determine the distribution of trematode larvae. The stages of this research began with the snails were collected from Tunggu Pampang Reservoir, Makassar City. Freshwater snails were collected at several points in the reservoir. Freswater snail collection using hand collecting method. The snails were put into a plastic bag with different types of snails and site of collection. The collected samples and cercariae were examined in the Tropical Disease Laboratory of the Study Program of DIII Medical Laboratory Technology, Megarezky University, South Sulawesi, Indonesia. Freshwater snails are placed on a petri dish and their shells were gently crushed with a stamper. Dropped with aquadest on the crushed snail shell. The next step was observed using a microscope to determine the presence of cercariae. Cercariae found then identified according to morphological classification as previously study. A total number of 500 freshwater snail were collected in Tunggu Pampang Reservoir. The results showed that overall snails infected with cercariae was 33,4%. The highest prevalence of cercariae in Indoplanorbis exustus was 94.3%. Total of Echinostoma cercariae found (n = 224) compared to furcocercous cercariae (n = 5). Cercariae of Echinostoma sp., Fasciola gigantica, Fasciolopsis buski living in Tungu Pampang Reservoir can cause diseases in humans and animals. Larval trematodes can be controlled in snails using reducing parasite contamination, monitoring surveillance, information dissemination, and preventive education.
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Vignoles, P., G. Dreyfuss e D. Rondelaud. "Larval development of Fasciola hepatica in experimental infections: variations with populations of Lymnaea truncatula". Journal of Helminthology 76, n. 2 (giugno 2002): 179–83. http://dx.doi.org/10.1079/joh2002112.
Testo completoAbstract (sommario):
AbstractA retrospective study was undertaken on 70 French populations of Lymnaea truncatula experimentally infected with Fasciola hepatica to determine whether or not susceptibility of snails to infection influenced redial and cercarial production. Results were compared with those obtained from two control populations, known for prevalences higher than 60% when experimentally infected with F. hepatica. In the 70 other populations examined, the prevalences ranged from 2 to 75%. In 55 of these populations, where the prevalence was more than 20%, a high proportion (50.1–56.8%) of snails died after cercarial shedding, whereas in the other groups (non-shedding snails with the most differentiated larvae being free cercariae, rediae containing cercariae, immature rediae, or sporocysts, respectively), snail death was significantly less. In 11 populations, where the prevalence values were 5–19%, only 14% of snails died after cercarial shedding, whereas snails with free cercariae, rediae with cercariae, or immature rediae showed significant increases in snail mortality. In the remaining four snail populations, with prevalences of less than 5%, the most differentiated larval forms were only immature rediae and/or sporocysts. Overall, the number of rediae containing cercariae significantly decreased with decreasing prevalence values. The low prevalence of experimental infection in several populations of snails might be explained by the occurrence of natural infections with miracidia originating from a mammalian host other than cattle, and/or by genetic variability in the susceptibility of snails to infection.
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PASZKIEWICZ, WALDEMAR, KRZYSZTOF SZKUCIK, MONIKA ZIOMEK, MICHAŁ GONDEK e RENATA PYZ-ŁUKASIK. "Occurrence of Salmonella spp. and Listeria spp. in snail meat". Medycyna Weterynaryjna 74, n. 2 (2018): 6074–2018. http://dx.doi.org/10.21521/mw.6074.
Testo completoAbstract (sommario):
The objective of the research was to determine the occurrence of microorganisms of the Salmonella spp. and Listeria spp. in raw and frozen (cooked) snail meat obtained from both free-living and farmed edible snails. The research material comprised meat samples collected from three snail species (25g from each), that is, Roman snail (Helix pomatia – HP), small brown garden snail (Cornu aspersum aspersum – CAA) and large brown garden snail (Cornu aspersum maxima – CAM). Roman snails came from their natural environment and were harvested in Wielkopolska Voivodeship and Lower Silesia Voivodeship (regions A and B, respectively). The Cornu genus snails were obtained from two heliciculture farms located in the abovementioned voivodeships (farms A and B, respectively). On both farms, the snails were maintained under the mixed rearing system. The raw meat samples taken from the edible portion of snails, that is, the foot with collar and a fragment of the mantle, were obtained after the snails were sacrificed in the laboratory. The frozen meat samples, on the other hand, came from a snail meat processing facility. A total of 300 samples were examined for the presence of Salmonella spp., and 240 for the presence of Listeria spp. The research also included pooled soil samples of 0.5 kg each collected from polytunnels (in the pre-fattening stage) and outdoor farming plots (in the fattening stage). The tests for the Salmonella presence were performed in accordance with Polish standard PN-EN ISO 6579:2003, and the test for Listeria complied with PN-EN ISO 11290-1:1999. Listeria monocytogenes was identified by the PCR technique. Salmonella spp. were not detected in any of the 300 samples of raw and cooked snail meat under study. Nor were these pathogens isolated from the soil samples. The absence of these bacteria in the raw meat samples indicates that Salmonella spp. did not occur in either the natural habitat of Roman snails or the two farms producing Cornu genus snails. On the other hand, bacteria of Listeria spp. were detected in 101 (42.1%) snail meat samples. A particularly high load of microbiota was found in raw meat, as these bacteria contaminated from 60% (for HP from region A and CAM from farm B) up to 75% (for CAA from farm A) of samples. Notably, a markedly lower percentage (35%) of samples containing Listeria spp. was found only among the Roman snail raw meat samples from the region B. Listeria spp. were also detected in all the soil samples. Thermal treatment of meat achieved a substantial reduction in the load of Listeria spp., but did not eliminate it. The frequency of this genus in frozen meat samples was from 63.5% (for CAM from farm A) to 15.4% (for CAA from farm B) of that in raw meat. The PCR technique was used identify 15 selected strains, including 11 from raw meat samples and 4 from cooked meat. A total of 5 isolates were recognized as Listeria monocytogenes (2.1% of all samples examined and 4.95% of samples with Listeria spp.). All of them originated from the raw meat of farmed snails, including one (CAA) from the farm A and four (3 CAA and 1 CAM) from the farm B. Bacteria of the Salmonella and Listeria genera occur in the natural habitat of edible snails, which poses a potential hazard to human health. Effective implementation of control programmes at the primary production stage is the first step that could considerably limit the presence of these pathogens in farmed snails and, consequently, in snail meat. .