Lymnaea Auricularia Research Articles

Mammalian and Avian Larval Schistosomatids in Bangladesh: Molecular Characterization, Epidemiology, Molluscan Vectors, and Occurrence of Human Cercarial Dermatitis.

Schistosomiasis is a neglected tropical disease (NTD) caused by blood flukes (Schistosoma spp.). Schistosomatids affect a wide array of vertebrate hosts, including humans. In the present study, multiple species of schistosomatids were identified by isolating schistosomatid cercariae (SC) from naturally infected snails. We also described different biotic and abiotic factors influencing SC infections in snails and reported human cercarial dermatitis (HCD) for the first time in Bangladesh. A total of 22,012 snails of seven species: Lymnaea auricularia, L. luteola, Indoplanorbis exustus, Physa acuta, Viviparus bengalensis, Brotia spp., and Thiara spp., were collected and examined. Among these snails, 581 (2.6%) belonging to five species: L. luteola, L. auricularia, P. acuta, I. exustus, and V. bengalensis, were infected with SC. The rate of infection was the highest for L. luteola (11.1%), followed by L. auricularia (5.3%), and was the lowest for V. bengalensis (0.4%). Prevalence in snails was the highest in September (16.8%), followed by October (9.5%) and November (8.8%), and was the lowest in colder months, such as January (1.8%) and February (2.1%). Infections with schistosomatids were more common in larger snails and snails collected from sunny areas. We confirmed the presence of Schistosoma indicum, S. incognitum, S. nasale, S. spindale, and Trichobilharzia szidati by PCR and sequencing. Through a questionnaire survey, we detected HCD in 214 (53.5%) individuals, and the infection rate was almost equally distributed across all professions. Collectively, the present results suggest that lymnaeid snails are the main vector for Schistosoma spp. prevalent in Bangladesh, and schistosomatids with zoonotic potential are also prevalent.

N – alkanes in molluscs of Shatt Al-Arab river

This study comprises monitoring of the n-alkanes in the Shatt Al-Arab river by using the seven molluscs species as bioindicators. These species are: snails Lymnaea auricularia, Theodoxus jordani, Physa acuta, Melanopsis nodosa, and Melanoides tuberculata and bivalves Corbicula fluminea and Corbicula fluminalis. The species of molluscs are collected from different locations of the Shatt Al-Arab river (along the region extended from Abu Al-Khasib to Garmat-Ali) during 2004 and 2005. Each species consisted of at least 3500 adult of individuals of uniform sizes. The hydrocarbons from these species were extracted and analyzed both by spectroflurometer (total hydrocarbons) and high resolution capillary gas chromatography (n-alkanes). The concentrations of total hydrocarbons in mollusc’s species of the Shatt Al-Arab river ranged from 1.93 μg/g dry weight in T. jordani to 26.56 μg/g dry weight in C. fluminea. The range of carbon chain length of n-alkanes in these individuals was ranging from C13 - C32. The bimodal distribution with two maxima around C17 and C27 suggested two different sources of hydrocarbons both biogenic and anthropogenic. The dominance of the odd carbon numbers n-alkanes (C15, C17, C25 and C29) in the mollusc’s species indicated biogenic origin of hydrocarbons .The pristane values were more than those of phytane. Pristane and phytane in the mollusc’s species suggest biogenic origin. CPI values are more than one indicating a biogenic origin of hydrocarbons in these species. Squalane is also present in some these species intimately related to anthropogenic sources of hydrocarbons. The presence of Unresolved Complex Mixture (UCM) reflects the anthropogenic sources. The lower fat contents were found in T. jordani (0.33 mg/g) and the higher were in C. fluminea (0.98 mg/g). A significant relationship is found between the fat contents and hydrocarbons concentrations in the tissues of molluscs species (r = 0.8 - 0.9).

SCHISTOSOMA TURKESTANICA SKRJABIN, 1913: TOPOGRAPHY OF CERCARIAE EMISSION FROM A SPONTANEOUSLY INVADED OBLIGATE INTERMEDIATE HOST LYMNAEA AURICULARIA L., 1758

The algorithm of ethology of cercariae (=furcocercariae) of the trematode Schistosoma turkestanica Skrjabin, 1913, when implementing the scenario of the emission process from the naturally invaded mollusk Lymnaea auricularia L., 1758, is constant and consists of two periods. In the first, preliminary, larvae migrate into the subepithelial tissue of the mollusk. In the second, final, consisting of two phases, furcocercariae pierce the epithelial tissue "from the inside out" and go out into the external environment. Initiation by cercariae of the process of exit from the body of the mollusk Lymnaea auricularia L., 1758, excludes the possibility of suspension or reverse development of the sequence of events. Anatomical and topographic areas of the body of the obligate intermediate host Lymnaea auricularia L., 1758, are not limiting factors for the realization of the final phases of the emission process of the cercariae of the trematode Schistosoma turkestanica Skrjabin, 1913. The resulting vector of interstitial migration of cercariae, stochastically oriented in the direction of the shell mouth of the mollusk Lymnaea auricularia L., 1758, brings the larva into the subepithelial tissue in any topographic area of the body of the intermediate host, where the integumentary epithelium borders with the external environment. To denote the anatomical topography of the apical part of the body of the cercarium trematode Schistosoma turkestanica Skrjabin, 1913, we propose to use the term "apical talus organ". The process of emission of cercariae of the trematode Schistosoma turkestanica Skrjabin, 1913, from the body of the mollusk Lymnaea auricularia L., 1758, is invasive for the latter.

FORMATION OF BIODIVERSITY OF THE FAUNA OF ECTO- AND ENDOPARASITES ON THE ARARAT PLAIN OF ARMENIA

Our studies were aimed at analyzing biodiversity of ecto- and endoparasites of sheep, cattle, rabbits, domestic birds and dogs in the lowland zone of the Republic, with semidesert climate and height of 850 m above the sea level. This is one of the warm regions of the Republic. The studies performed have established moderate and high degree of animal infection with parasites. We identified 33 parasite species, mostly helminths (15 species), including 10 species of nematodes (Trichocephalus ovis, Nematodirus spathiger, Haemonchus contortus, Chabertia ovina, Dictyocaulus filaria, Muellerius capillaris, Protostrongylus spp., Passalurus ambiqus, Ascaridia galli, Heterakis gallinarum), 4 species of trematodes (Fasciola hepatica, F. gigantica, Dicrocoelium dendriticum, Paramphistomum cervi), 1 species of cestodes (Moniezia expansa), 9 protozoan species (Piroplasma bigeminum, Babesia ovis, Eimeria perforans, E. magna, E. irresidua, E. tenella, E. acervulina), 7 species of ticks, 1 species of insects, and 1 species of leishmaniasis vector, the mosquitos from the genus Phlebotomus. We registered 5 species of freshwater molluscs (Lymnaea auricularia, L. stagnalis, L. ovata, L. truncatula, Planorbis planorbis), and 2 species of terrestrial molluscs (Helicella derbentina, Napaeopsis hohenackeri).

MORPHOLOGICAL AND BIOINFORMATICS STUDY FOR RADIX AURICULARIA SNAILS IN FRESHWATER IN BASRAH PROVINCE, IRAQ

Radix auricularia (Lymnaea auricularia) snails are the main intermediate host of Fasciola gigantica in the middle and South of Iraq. Recently, some studies suggest these snails are not present in Iraq, in particular Basrah province. Thus, the current study was aimed to use the bioinformatics analysis in the determination of Radix sp. in Basrah and also aimed to identify morphological characteristics of this species in the AL-Sewaib river, Basrah. Four hundred R. auricularia snails were collected from the AL-Sewaib river during May 2018 to March 2019. The results of the bioinformatics analysis showed according to the mitochondrial cytochrome c oxidase subunit I, the presence of R. auricularia snails in Basrah province and these snails are more closely related to Iranian R. auricularia snails than those for European counties and Russia. This study also displayed the existence of the polymorphism phenomenon in R. auricularia snails collected from the AL-Sewaib river which there were six different forms (A, B, C, D, E and F). These forms had variations in the colour and form of shells along with a variation in the number of eggs (30-56) per an egg mass. In addition to this, these R. auricularia forms had variations in their distributions. Form E had the highest spread percentage (33%) followed by 17, 15, 14, 11 and 10% for forms B, D, C, A and F, respectively. These forms had also variations in their morphological characteristics. The largest form was the form D whereas the smallest form was the form B but other forms A, C, E and F were similar and had moderate sizes.Thus, the current study concludes the existence of R. auricularaia snails in Basrah as a representative city for the southern part of Iraq and also confirmed the presence of the polymorphism phenomenon in the members of R. auricularaia obtained from the AL-Sewaib river.

A faunistic survey of snails and their infection with digenean trematode cercariae in Bandar-e Anzali at the littoral of the Caspian Sea.

Trematodes are known as a diverse group of endogenous parasites, which snails as their intermediate hosts can dramatically affect parasite transmission dynamics. Snails play a key role in life cycles of digenean trematode. However, there has not been much faunistic surveys in terms of snails' distribution in Iran. The current study was aimed to identify snail's fauna and their current geographic distribution in four regions of Guilan province, Iran. Several species of snails (land and freshwater snails) were obtained from 4 different areas (2018-2019), and then samples were separately transferred to the laboratory. Diagnosis of snails was then performed according to morphometric characteristics including dextral or sinistral shell, shape, color and size of shell. Moreover, radula was stained and then photographed under microscopic examination. Furthermore, 25% of any species were tested for cercarial infection. In total, 2082 snails belonging to 12 species were identified based on the morphological characteristics. Land snails were identified to be Helicella sp. (46.4%), Helix aspersa (34.1%), Helicopsis sp. (8%), Pomatia sp. (6.7%) and Oxyloma elegans (4.8%). Moreover, freshwater snails were Physa acuta (30.6%), Lymnaea auricularia (25.8%), Lymnaea gedrosiana (18.7%), Lymnaea palustris (8.9%), Lymnaea truncatula (8.1%), Planorbis sp. (6.4%) and Lymnaea stagnalis (1.5%). In collected snails, Lymnaea auricularia (0.66%) and Lymnaea gedrosiana (0.45%) were the only snails harboring cercariae (Gymnocephalus cercariae). There was no statistically significant difference between the cercarial infection and snail species (P<0.05). Comprehensive field studies are highly needed for better evaluation of the snail biodiversity in the Caspian Sea region due to the particular climatic conditions and the high prevalence of trematodosis.

A novel lectin from Freshwater Snail (Lymnaea auricularia; L., 1758): Extraction, Characterization, partial purification and his possible role in host- parasite interaction

A novel lectin from Freshwater Snail (Lymnaea auricularia; L., 1758): Extraction, Characterization, partial purification and his possible role in host- parasite interaction

Investigating the Effect of Lymnaea auricularia (snail) Powder on Different Species of Pathogenic Bacteria

The aim of this study was to investigate the antibacterial activity of Lymnaea auricularia (snail) tissue powder and shell powder against different human pathogenic bacteria (Escherichia Coli, Pseudomonas aeruginoa and Klebsiella pneumonia). Four concentration was tested (75,100.125,150) mg\ml of the powder with well diffusion assay. The highest activity of shell powder was in E. Coli at 75mg\ml concentration(19mm) inhibition zone, while the highest activity of tissue powder was in P. aeruginoa at 150mg\ml concentration with inhibition zone (28 mm). The powder extracts ‘ antimicrobial activity reveals that they may have biologically active metabolites.

TREMATODE FAUNA OF MOLLUSKS OF THE KATTAKURGAN RESERVOIR OF THE SAMARKAND REGION

The paper presents research data on the fauna and qualitative composition of trematode cercaria of the families that maturate in mollusks, namely, Lymnaeidae, Planorbidae, and Physidae of the Kattakurgan Reservoir of the Samarkand Region. The work was carried out in the spring-summer and autumn time of 2017–2019 in the Kattakurgan Reservoir. There were 7510 mollusks (Lymnaeidae – 4116 specimens, Planorbidae – 2280 specimens and Physidae – 620 specimens) collected and investigated according to the known malacology methods. As our collections showed, 5 species were found here in 2017–2019 – L. auricularia, L. subdisjuncta, Costatelia acuta, Planorbis planorbis, and Anisus covexiusculus. Among them – Lymnaea auricularia and L. sudisjuncta live on the lower layers of plants, and are sometimes found on the slopes of the dam. Seven species of mollusks infected with trematode larvae were found in the examined reservoir. We found that the fauna of trematode cercaria from the studied reservoir is represented by 16 species belonging to 15 genera. The richest species diversity of cercariae in mollusks Planorbis planorbis is 6 species. Cercariae are represented by 5 species in mollusks Radix auricularia in the studied region.

Development of Cytochrome B, a new candidate gene for a high accuracy detection of Fasciola eggs in fecal specimens

Fasciolosis among domestic ruminants has resulted in a decrease in the production of milk products and has occasionally led to the deaths of young ruminants due to of acute infections. This study aimed to discriminate between the eggs of Fasciola gigantica and other trematode eggs in samples collected from ruminant feces specimens using PCR-based methods with the new candidate gene Cytochrome B (CYTB). A species-specific primer was developed with a high degree of sensitivity (3.285 pg). The primer was able to amplify the F. gigantica genomic DNA and there were no positive results with the other related trematodes (Paramphistomum sp., Orthocoelium sp., Fischoederius sp., Calicophoron sp., Echinostoma revolutum, E. cinetorchis, E. ilocanum and Isthmiophora hortensis), freshwater snails (Lymnaea auricularia, Bithynia siamensis, Indoplanorbis exustus, Melanoides tuberculata, Tarebia granifera) or definitive hosts (Bos primigenius and Bubalus bubalis). The minimum concentration of DNA from eggs that could be give a positive result was 3.285 pg. Moreover, the results of the study confirmed the existence of F. gigantica in Nakhon Pathom Province with a high prevalence (28.57%) and revealed the area of infection through epidemiological mapping. Thus, the species-specific primer and epidemiological data in this study may be helpful for use in epidemiological studies, phylogenetic studies and veterinary studies in the future.

ETHOLOGY OF THE TREMATODE CERCARIAE SCHISTOSOMA TURKESTANICA SKRJABIN, 1913, WHEN EMITTED FROM NATURALLY INVASIVE LYMNAEA AURICULARIAL MOLLUSKS, 1758

The characteristics of ethnological characteristics of cercaria trematodes Schistosoma turkestanica Skrjabin, 1913 are detailed with emission from naturally invasive intermediate hosts, Lymnaea auricularia mollusks L., 1758.The modern correct species name of the dioecious trematodes of the Schistosomatidae family, the parasitic circulatory system of cattle in the Central Asian region, should be considered Schistosoma turkestanica Skrjabin, 1913.Spontaneous emission of furcocercarium Sch. turkestanica from invasive L. auricularia, can occur in various parts of the mollusk's body surface. The process of the release of the larva into the environment proceeds according to the original algorithm, accompanied by its morpho- functional adaptations, taking 15–17 seconds. The active initial transient phase of piercing “from inside-out” in the first 2–3 seconds is ensured by the body of the larva, which is drawn in length, taking the shape of a needle. Then, the tail of the cercaria is released from the puncture site. Tissue damage in the area of release of the larvae was not visually marked.Fourcocarii Sch. turkestanica have positive photo– and negative geotaxis, which modulate continuous two-phase, mainly vertical mobility, ensuring their long-term stay in the plankton state in the surface layers of water. Features of cervary ethology increase the likelihood of targeted active contact and the effectiveness of the attack of definitive hosts of the trematodes.

تقييم قابلية نوعين من قواقع المياه العذبة على مراكمة بعض العناصر في كتلتها الحية والاصداف

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The ability of snails Melanopsis nodosa and Lymnaea auricularia has been estimated on bioaccumulation for Zn, Al, Li, V, Ce and P in soft tissue and shell. Significant correlation for Zn, Al and P concentration was found in both species. The amount and ability of bioaccumulation for all elements in the two species were convergent except for Al it was in L. auricularia higher than M. nodosa more than four times. The concentrations of Zn, Al, V, Ce in soft tissue were higher than shell in both species except Li it was high in L. auricularia shell in comparison with the soft tissue. The elements followed this order P &lt; Al &lt; Zn &lt; V &lt; Li &lt; Ce in soft tissue and shell except for L. auricularia shell in which Al concentration is more than P. &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; قدرت قابلية القوقعان Melanopsis nodosa و &nbsp;Lymnaea auriculariaعلى التراكم الحيوي لعناصر الزنك Zn والألمنيوم Al والليثيوم Li والفناديوم V والسيريوم Ce فضلا عن الفسفور P في كتلتها الحية والاصداف. كان هناك ارتباط معنوي لتركيز عناصر للزنك والألمنيوم والفسفور بين كلا النوعين، كان مقدار وقابلية التراكم الحيوي لجميع العناصر بين النوعين متقاربة باستثناء عنصر الألمنيوم اذ كان في L. auricularia اعلى من M. nodosa باكثر من اربع اضعاف، كان تركيز عناصر &nbsp;Znو Alو Vو Ceو Pفي الكتلة الحية اعلى من الاصداف في كلا النوعين باستثناء عنصر الليثيوم الذي كان تركيزه في اصداف L. auricularia اعلى من كتلتها الحية. اتبعت العناصر النسق V &lt; Li &lt; V &lt; &nbsp;Zn&lt; Al &lt; P في الكتلة الحية والاصداف لكلا النوعين باستثناء اصداف L. auricularia كان فيها تركيز الألمنيوم اعلى من الفسفور. &nbsp

Isolation, Purification and Identification of Blue-green Alga Hapalosiphon aureus and Evaluation of its Histopathological Effects on Fresh Water Snail Lymnaea auricularia

Isolation, Purification and Identification of Blue-green Alga Hapalosiphon aureus and Evaluation of its Histopathological Effects on Fresh Water Snail Lymnaea auricularia

Effects of climatic factors on prevalence of developmental stages of Fasciola gigantica infection in Lymnaea snails (Lymnaea auricularia var rufescens) in Bangladesh

The present study was conducted to investigate the prevalence of developmental stages of Fasciola gigantica infection in Lymnaea snails and their populations in Sylhet region of Bangladesh. A total of 1865 Lymnaea snails were collected and examined, of which 56 (3%) were found to having infected with developmental stages of Fasciola gigantica. Only 4.08% infected of 515 snails were collected from Biswanath Upazilla followed by 3.16% of 443 from Beanibazar, 2.53% of 396 from Balaganj then 2.40% of 292 Jaintapur Upazilla and the lowest 1.83% of 219 from Sylhet Sadar. Month-wise data, the prevalence of snail infections was observed to be the highest in May (5.06%) and August (5.61%) and the lowest in March (0.74%) and February (0.68%). However there was no infection observed through November to January. Seasonal prevalence of the developmental stages of F. gigantica infection in Lymnaea snails was also studied. Highest prevalence (4.63%) was recorded during rainy season and lowest prevalence (0.76%) was recorded during winter season. The study revealed that the developmental stages of F. gigantica infection in snail populations decreases from November to January and increases from February to October and highest in August and September in Sylhet region of Bangladesh.

Characteristics of Macroinvertebrates Food Webs affected by Dry Channel in an Intermittent Stream System of the Echi River in Japan

The purpose of study is to identify trophic pathways from organic matter to macroinvertebrates in terms of the consumer and to characterize the food webs in an intermittent stream system of the Echi River in Japan. The δ13C values of macroinvertebrates and their potential food sources indicated the scraper (Psephenoides spp., Ecdyonurus levis) and collector-gatherer (Ephemera strigata, Paraleptonphlebia chocolata) feed on periphyton and POM (particulate organic matter) in situ. Davidius lunatus, and Hexatoma spp., which were identified as predators, may feed upon Ephemera strigata and Stenelmis larvae, respectively. At station characterized by seepage water, the δ15N values of Ecdyonurus levis, Lymnaea auricularia, and Rhyacophila nigrocephala larva probably showed relatively lower values according to its diets. Even in homogenous species, the trophic pathways of macroinvertebrates in situ exhibited considerable variation; this reflected the trophic pathways from organic matter to the consumer depending on habitat characteristics in stream.

Association of Aquatic worms and infected snails with Digenean larvae

Six species of aquatic snails were sorted from three sites, the irrigation canal of Baghdad University campus (S1), River Tigris at Al-Za'afaraniah district / Baghdad(S2) , and River Euphrates at Al-Haideriah district Al-Najaf province(S2). The species included Melanopsis nodosa ;Melanoides tuberculata ; Thaiodaxsas jordani ; Lymnaea auricularia ; Physa acuta and Bellamya bengalensis. The first specis recorded the highest total number and was found in high density in the R. Euphrates site (S3), while the last species was the most widely distributed species, and found in all study sites. The last three species were found in Tigris river (S2) , while the first and last species were collected from the irrigation canal (S1).The result revealed that the species M. nodosa, M. tuberculata and L. auricularia were infected with Digenean larval stages, and the first species recorded the highest infection percentage of 60.04%, and the lowest percentage of 5.70% was recorded in L. auriculari , while M. tuberculata recorded a percentage of 38.98%.The oligochaetes Chaetogaster limnaei was sorted from the mantle cavity of L. auriculari and P. acuta, and it was noted that the first species accommodated more worms numbers than the second species. Twelve Species of family Naididae worms (subfamily Naidinae and subfamily Pristininae) , in addition to Aeolosoma leidyi of family Aeolosomatidae were sorted from the specific aquarium of each snail species. The leech Glossiphonia heteroclite was also recorded. The Nematodes worms were recorded the highest number sorted from the aquarium of L.auricularia, which are the most associate species, and 10 species of 49 individuals of worms were sorted from its aquarium, specially Dero ( Dero)digitata. In general, the infected snails, M. nodusa, M. tuberculata, and L. auricularia showed the highest association with worms, and from their aquaria 48, 37 , and 49 individuals of worms . with a number of 8,3, and 18 species respectively.

Association of Aquatic worms and infected snails with Digenean larvae

Six species of aquatic snails were sorted from three sites, the irrigation canal of Baghdad University campus (S1), River Tigris at Al-Za'afaraniah district / Baghdad(S2) , and River Euphrates at Al-Haideriah district Al-Najaf province(S2). The species included Melanopsis nodosa ;Melanoides tuberculata ; Thaiodaxsas jordani ; Lymnaea auricularia ; Physa acuta and Bellamya bengalensis. The first specis recorded the highest total number and was found in high density in the R. Euphrates site (S3), while the last species was the most widely distributed species, and found in all study sites. The last three species were found in Tigris river (S2) , while the first and last species were collected from the irrigation canal (S1).The result revealed that the species M. nodosa, M. tuberculata and L. auricularia were infected with Digenean larval stages, and the first species recorded the highest infection percentage of 60.04%, and the lowest percentage of 5.70% was recorded in L. auriculari , while M. tuberculata recorded a percentage of 38.98%.The oligochaetes Chaetogaster limnaei was sorted from the mantle cavity of L. auriculari and P. acuta, and it was noted that the first species accommodated more worms numbers than the second species. Twelve Species of family Naididae worms (subfamily Naidinae and subfamily Pristininae) , in addition to Aeolosoma leidyi of family Aeolosomatidae were sorted from the specific aquarium of each snail species. The leech Glossiphonia heteroclite was also recorded. The Nematodes worms were recorded the highest number sorted from the aquarium of L.auricularia, which are the most associate species, and 10 species of 49 individuals of worms were sorted from its aquarium, specially Dero ( Dero)digitata. In general, the infected snails, M. nodusa, M. tuberculata, and L. auricularia showed the highest association with worms, and from their aquaria 48, 37 , and 49 individuals of worms . with a number of 8,3, and 18 species respectively.

Experimental life history and biological characteristics of Fasciola gigantica (Digenea: Fasciolidae).

This study was conducted to investigate the life history, morphology, and maturation of larval stages and adult worms of Fasciola gigantica in experimental mice. Lymnaea auricularia rubiginosa was used as the intermediate host, and Oryza sativa was used for encystment of the metacercariae, while Mus musculus was used as the definitive host for maturation study. Fresh eggs from the gall bladder of water buffaloes fully developed into embryonated ones and hatched out at days 11-12 after incubation at about 29ºC. Free-swimming miracidia rapidly penetrated into the snail host, and gradually developed into the next larval stages; sporocyst, redia, and daughter redia with cercariae. Fully-developed cercariae were separated from the redia and shed from the snails on day 39 post-infection (PI). Free-swimming cercariae were immediately allowed to adhere to rice plants, and capsules were constructed to protect metacercariae on rice plants. Juvenile worms were detected in intestines of mice at days 3 and 6 PI, but they were found in the bile duct from day 9 PI. Juvenile and adult flukes were recovered from 16 mice experimentally infected with metacercariae, with the average recovery rate of 35.8%. Sexually mature adult flukes were recovered from day 42 PI. It could be confirmed that experimentally encysted metacercariae could infect and develop to maturity in the experimental host. The present study reports for the first time the complete life history of F. gigantica by an experimental study in Thailand. The obtained information can be used as a guide for prevention, elimination, and treatment of F. gigantica at environment and in other hosts.

Distribution Patterns of Vector Snails and Trematode Cercaria in their Vectors in Some Selected Areas of Mymensingh

Different species of vector snails carry larval stages of different trematodes. Studies were performed to investigate different snail species and parthinate of trematodes carried by them, in some selected areas of Mymensingh Sadar, Mymensingh. Snails were collected by hand picking method and examined after crushing. Among 864 tested snails, it revealed the presence of six species of snails like Lymnaea auricularia 145 (16.8%), Lymnaea luteola 205 (23.7%), Indoplanorbis exustus 273 (31.6%), Vivipara spp. 164 (18.9%), Brotia spp. 35 (4.1%) and Pila spp. 42 (4.8%) in the study areas. Among them 5.8% L. luteola and 6.2% L. auricularia were infected with gymnacephalus cercariae. Again, 1.4% L. auricularia and 1.8% I. exustus were infected with echinostome cercaria. In this study, 1.8% Vivipara spp. and 2.6% I. exustus were positive for furcocercus cercaria. On the other hand, 1.8% Vivipara spp. was positive for xiphidocercus cercariae and 1.8% I. exustus was also positive for amphistome cercariae. One or more species of snails were found to harbor single or mixed types of cercariae such as gymnacepahlus, echinostome and furcocercous. Population densities of different species of snails were determined in per unit time which were statistically significant (p&lt;0.01). More studies are needed to focus on the determination of different vector snails and cercariae carried by them throughout the Bangladesh especially from plain lands, hilly areas, alluvial lands and coastal areas during four conventional seasons.DOI: http://dx.doi.org/10.3329/jesnr.v5i2.14599 J. Environ. Sci. &amp; Natural Resources, 5(2): 37-46 2012

Snail abundance in freshwater canals in the eastern province of Saudi Arabia and acute toxicity studies of copper sulphate in Biomphalaria arabica and Lymnaea auricularia

The present study aimed to investigate the distribution of three species of freshwater snails, namely; Biomphalaria Arabica ; Planorbidae, Lymnaea auricularia ; Lymnaeidae and Melanoides tuberculatus ; Thiaridae in two different parallel canals (the concrete irrigation and the earthen drainage canals) in the eastern province of Saudi Arabia and the effect of copper sulphate pentahydrate (CuSO 4 .5H 2 O) on mortality of the first two species after 24 h of exposure. The physico-chemical properties of the water especially, temperature and pH were determined as important factors for snail distribution. The results show that the water temperature and the pH of the two canals were almost the same. The range of water temperature was 25.8 to 28.3°C, while the water pH was 6.6 to 6.8. The two canals were occupied by three species of aquatic snails viz. B. arabica , L. auricularia and M. tuberculatus . The bioassay of CuSO 4 .5H 2 O on only two snail species showed 24 h–LC 50 as 5.7 ppm for B. arabicus and 7.8 ppm for L. auricularia. This result reveals that CuSO 4 .5H 2 O was highly effective in snail eradication. On the basis of the present study, it is recommended that some further studies on the canals including all environmental factors should be investigated for their role in aquatic snail distribution. However, the chronic effect of lower lethal dose of CuSO 4 .5H 2 O on the snails mortality and their effects on developmental stages should be investigated, and some local plant extract should also be tried for their potency on snail mortality. Key words : Biomphalaria, Lymnea, Melanoides , distribution, freshwater snails, copper sulphate, Saudi Arabia.