scispace - formally typeset
Search or ask a question

Showing papers on "Biomphalaria alexandrina published in 2017"


Journal ArticleDOI
TL;DR: The results open a new field for controlling the infectious diseases through eradication of their vectors by the way that avoids the resistance recorded from the successive chemical application in this field.
Abstract: AIM This research was conducted to evaluate the molluscicidal and mosquitocidal efficacy of silica nanoparticles in the eradication of the larvae and pupa of malaria and filariasis vector as well as vectors of rift-valley fever virus (Culex pipiens); Schistosoma mansoni vector and Biomphlaria alexandrina (snail and egg masses). MATERIALS AND METHODS Hydrophilic nanosilica particles (NSPs) were characterized using transmission electron microscope during the preliminary part of the study; the stages were exposed to upgrade concentrations of NSP from 50 to 1200 ppm each for 24-36 h exposure time. The highly effective concentrations were re-evaluated at lower exposure time as 3, 6, and 12 h. RESULTS Lethal concentration (LC50) and LC90 versus mosquito larvae were (350 ppm/24 h and 1400 ppm/24 h, respectively). C. pipiens pupae proved slight high tolerance versus the effect of these nanoparticles as the two previous doses increased to 680 ppm/6 h and 1300 ppm/24 h. The LC50 and LC90 versus B. alexandrina were increased to 590 ppm/6 h and 980 ppm/48 h, respectively. Moreover, the embryonated snail egg masses appear more susceptible to the toxic effect of these nanoparticles than the non-embryonated eggs as the LC50 and LC90 were increased to 1450 ppm/12 h and 1250 ppm/48 h, respectively, for embryonated eggs, and it was 1400 ppm/24 h and 1890 ppm/48 h, respectively, for non-embryonated one. CONCLUSION The results open a new field for controlling the infectious diseases through eradication of their vectors by the way that avoids the resistance recorded from the successive chemical application in this field.

27 citations


Journal ArticleDOI
TL;DR: Study of the molluscicidal impacts of eleven isolates of Bacillus thuringiensis which were isolated from soils of six Egyptian governorates toward Biomphalaria alexandrina snails showed that, B. thuringienis provides an effective biological control agent against B. alexandra snails.

21 citations


Journal ArticleDOI
TL;DR: Findings prove the potent activity of aqueous seed extract of M. oleifera against the intermediate hosts of Schistosoma mansoni and provide a considerable scope in exploiting local indigenous resources for snails’ molluscicidal agents.
Abstract: Schistosomiasis is one of the neglected tropical diseases. It is a snail-borne trematode infection, and Biomphalaria alexandrina snails are the intermediate host of Schistosoma mansoni in Egypt. The objective of this study is to evaluate the molluscicidal activity of the aqueous seed extract of Moringa oleifera against B. alexandrina snails. The results showed that this aqueous extract was lethal for B. alexandrina snails (LC50 0.27 g/l; LC90 0.41 g/l). Exposure of snails to the sublethal concentrations of this aqueous extract caused a considerable reduction in survival rates and hatchability rates of eggs of these snails. Moreover, it negatively affected some biochemical aspects, where it increased the levels of transaminases (ALT and AST), while it decreased the concentrations of total protein, albumin, and globulin concentration. Histological examinations of the digestive gland of snails exposed to the sublethal concentrations of aqueous seed extract of M. oleifera revealed severe damage in the digestive cells, where they lost their tips and some were degenerated, while the secretory cells increased in number. Regarding the hermaphrodite gland, there were losses of connective tissues and irregular sperms, and the eggs were degenerated. These findings prove the potent activity of aqueous seed extract of M. oleifera against the intermediate hosts of Schistosoma mansoni and provide a considerable scope in exploiting local indigenous resources for snails’ molluscicidal agents.

18 citations


Journal ArticleDOI
TL;DR: This study indicated that the predator, S. urinator, may be a suitable bio-control agent in connection with Schistosoma intermediate hosts in the aquatic area.
Abstract: The water bug, Sphaerodema urinator (Hemiptera : Belostomatidae), shares the same habitat of the freshwater snails in ponds, lakes, and streams. Studies conducted in lakes show that fish and crayfish predators play an important role in determining the abundance of freshwater snails. In contrast, shallow ponds and marches often lack fish and crayfish but have abundant insect predators. This study has been carried out to evaluate the predatory potential of S. urinator adult on two freshwater snails that serves as intermediate hosts of Schistosoma. Laboratory evaluation of predation by S. urinator on these intermediate hosts revealed that the adult bug could kill and consume the two intermediate hosts: Bulinus truncatus and Biomphalaria alexandrina. The number of snails consumed differed according to the snail type, size, and density. The times taken for searching and handling times were depending on the snail size, type, and vulnerability of the predator. The predation rate varied also with respect to snail type and density. Prey size is a major factor influencing predator preferences. This study indicated that the predator, S. urinator, may be a suitable bio-control agent in connection with Schistosoma intermediate hosts in the aquatic area.

16 citations


Journal ArticleDOI
TL;DR: The B. alexandrina CNS transcriptome provides a resource for future research exploring parasite-host interactions in a simpler nervous system and increased understanding of the neural signaling mechanisms involved in the response of B. alexandrina to infection by S.mansoni larvae could lead to novel and highly specific strategies for the control of snail populations.
Abstract: Globally, more than 200 million people live at risk of the neglected tropical disease schistosomiasis (or snail fever). Larval schistosomes require the presence of specific snail species that act as intermediate hosts, supporting their multiplication and transformation into forms that can infect humans. This project was designed to generate a transcriptome from the central nervous system (CNS) of Biomphalaria alexandrina, the major intermediate host for Schistosoma mansoni in Egypt. A transcriptome was generated from five pooled central nervous systems dissected from uninfected specimens of B. alexandrina. Raw Illumina RNA-seq data (~ 20.3 million paired end reads of 150 base pairs length each) generated a transcriptome consisting of 144,213 transcript elements with an N50 contig size of 716 base pairs. Orthologs of 15,246 transcripts and homologs for an additional 16,810 transcripts were identified in the UniProtKB/Swiss-Prot database. The B. alexandrina CNS transcriptome provides a resource for future research exploring parasite-host interactions in a simpler nervous system. Moreover, increased understanding of the neural signaling mechanisms involved in the response of B. alexandrina to infection by S. mansoni larvae could lead to novel and highly specific strategies for the control of snail populations.

12 citations


Journal ArticleDOI
TL;DR: Huwa-san as a newly applied disinfectant can also be used as miracicidal and cercaricidal agent at small concentrations, despite being more toxic to B. alexandrina snails, the chronic effect of its sublethal concentrations is less harmful than chlorine.
Abstract: Many chemicals are applied for disinfecting purposes. Although chlorination is the most common procedure, it has many drawbacks. So there becomes an urgent need for new chemicals which are both effective and less harmful to other water fauna. The present work aims at investigating the comparative effects of chlorine and Huwa-san as a new disinfectant on Biomphalaria alexandrina snails which act as bioindicators of toxicity, besides evaluating their miracicidal and cercaricidal activities. The results showed that Huwa-san was more toxic on tested snails than chlorine, where the LC50 values were 21 and 1368.9 ppm, respectively after 24 h. Also, it was found that the activities of catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and glutathione peroxidase (GPX) in snails’ tissues were either induced or inhibited according to the tested disinfectant. Regarding reduced glutathione (GSH) content, it was increased as chlorine concentrations increased, while it reached its minimum content at the highest Huwa-san concentration. Such fluctuations were supported by histopathological examination of digestive and hermaphrodite glands, as prolonged exposure to chlorine led to more detrimental effects than Huwa-san concentrations. Moreover, Huwa-san was more effective on Schistosoma mansoni miracidia than on its cercariae, while the reverse was observed with chlorine. In conclusion, Huwa-san as a newly applied disinfectant can also be used as miracicidal and cercaricidal agent at small concentrations. Despite being more toxic to B. alexandrina snails, the chronic effect of its sublethal concentrations is less harmful than chlorine.

7 citations


Journal ArticleDOI
TL;DR: Data showed that high phosphorus and high nitrogen fertilisers have a negative impact on the growth rate of juvenile snails, and a significant increase in the catalase activity of snails that were exposed to ½ LC50 concentrations of balanced and high phosphorus fertilisers.
Abstract: Freshwater snails are often used to monitor aquatic pollution. The present study aims to use Biomphalaria alexandrina snails as bio-indicators for three types of NPK fertilisers (high nitrogen, high phosphorus and balanced). Data showed that high phosphorus and high nitrogen fertilisers have a negative impact on the growth rate of juvenile snails. Such observations were supported by determining antioxidant parameters in the digestive gland. Results indicated a significant increase in the catalase activity of snails that were exposed to ½ LC50 concentrations of balanced and high phosphorus fertilisers. Meanwhile, the glutathione S-transferase, glutathione peroxidase and reduced glutathione parameters showed varying results representing an increase or decrease in the activities of all treated groups after both the first and second weeks, according to the type of fertiliser the snails were exposed to.

5 citations


Journal ArticleDOI
TL;DR: The effects of sub-lethal concentrations of bisphenol A on some biochemical parameters in Biomphalaria alexandrina snail's hemolymph and tissues as well as on histological changes of the hermaphrodite gland were evaluated.
Abstract: The effects of sub-lethal concentrations of bisphenol A on some biochemical parameters in Biomphalaria alexandrina snail's hemolymph and tissues as well as on histological changes of the hermaphrodite gland were evaluated Adult snails were exposed to sub-lethal concentrations for four weeks and samples of snails were investigated after two and four weeks Total protein and albumin levels in hemolymph, as well as lipid peroxidation and glutathione contents of snails’ tissues, were measured After two weeks of exposure, total protein content and albumin levels decreased in all groups Elevation of lipid peroxidation levels was correlated with decreasing glutathione content in the treated snails Histological examination of the hermaphrodite gland revealed deformations in eggs and affected sperm production

4 citations


Journal ArticleDOI
TL;DR: Eight algal species were tested against Biomphalaria alexandrina snails; the intermediate host of Schistosoma mansoni; the bioassay tests revealed that Cystosiera barbata and Dictyota dichotoma were the most effective species.
Abstract: Schistosomiasis ranks the second amongst parasitic diseases affecting human. To reduce the incidence of this disease, several strategies were applied including snail control. Chemical control methods have many drawbacks, hence biological control became the concern of many studies. In this study, eight algal species were tested against Biomphalaria alexandrina snails; the intermediate host of Schistosoma mansoni. The bioassay tests revealed that Cystosiera barbata and Dictyota dichotoma were the most effective species, where the LC50 values were 2200 ppm and 560 ppm consequently. Prolonged exposure to LC25 (280 ppm) of D. dichotoma resulted in death of snails after two weeks. In addition, alterations in digestive glands of treated snails with LC5 (220 ppm) and LC25 (280 ppm) of C. barbata and D. dichotoma, respectively were obvious, as vacuolation of digestive cells were recorded after exposure of snails to LC5 of C. barbata. Moreover, exposure of snails to LC25 of D. dichotoma resulted in noticeable vacuolation of digestive cells and degenerated secretory cells; the lumen was nearly disappeared. The maximum elevations in the activities of both aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were observed after 2 weeks of exposure to LC5 (56 ppm) and LC15 (660.7 ppm) of D. dichotoma and C. barbata, respectively. The total protein contents of treated B. alexandrina snails were significantly different from that of control group after 2 weeks of exposure to different concentrations of both effective algae. Testing the sublethal concentrations of both effective algae on the Daphnia pulex showed that LC5 (220 ppm) of C. barbata and LC15 (168 ppm), LC25 (280 ppm) of D. dichotoma were the least harmful to these crustaceans.

4 citations


Journal ArticleDOI
TL;DR: Both digestive and hermaphrodite glands in Biomphalaria alexandrina snails were examined by light microscope (LM) and scanning electron microscopy (SEM) in a trial to clarify its immunological role as defense mechanism against the parasite infection.
Abstract: In this study, both digestive and hermaphrodite glands in Biomphalaria alexandrina snails were examined by light microscope (LM) and scanning electron microscopy (SEM) in a trial to clarify its immunological role as defense mechanism against the parasite infection. B. alexandrina snails used were exposed individually to Schistosoma mansoni miracidia; according to their responsq they were classified into infected snails (shed cercariae) and non-infected snails (failed to shed cercariae). Snails not exposed to S. mansoni miracidia used as control. LM showing great histological alteration in tissues, of the both glands in infected snails, these changes represented by degenerated both oocyte and spermatocyte in hermaphrodite gland in addition to degenerated digestive gland while non-infected snails showing mild degenerated ova with normal spermatocytes also degenerated miracidia. inside granuloma like structure with concentric layers of fibroblast and haemocyte could be observed. By SEM we could detect extensively damaged and fibrosed non-motile cilia with exfoliation of tegumental surface in in- fected B.alexandrina while non-infected ones showing attached numerous cilia with some ballooning of the folds.

1 citations


Journal ArticleDOI
TL;DR: Biomphalaria alexandrina snails showed refractory tendency with significant increase in hemocytes; granulocytes; indicating that defense mechanism was stronger than other ones, and selection for the most tolerant ones through the successive generations indicated tolerance upgrading phenotype.
Abstract: 575 SELECTION FOR CADMIUM-TOLERANCE IN BIOMPHALARIA ALEXANDRINA SNAILS CHARACTARIZATION BASED ON GENETIC STUDIES, AND SUSCEPTIBILITY TO SCHISTOSOMA MANSONI ASSOCIATION By SHADIA H. MOHAMED, HANAA M. M. EL KHAYAT, SAMIA M. FAWZI AND DINA G. TAWFIK Department of Zoology, Faculty of Science, Ain Shams University, Cairo 11566, and Environmental Research Laboratory, Theodor Bilharz Research Institute, Embaba P.O. Box 30, Giza, Egypt (*Correspondence: dina-Gamall@hotmail.com) Abstract Biomphalaria alexandrina snails were examined for their tolerance to cadmium (Cd) toxicity through three generations produced by self-fertilization by exposing snails to serial concentrations of Cd and selection for the most tolerant ones through the successive generations. Results showed a gradual increase in the LC50 & LC90 values via successive generations indicating tolerance upgrading phenotype. Also, the selected and non-selected snails were examined for susceptibility to Schistosoma mansoni and hematological criteria. B. alexandrina showed refractory tendency with significant increase in hemocytes; granulocytes; indicating that defense mechanism was stronger than other ones. The dendro-gram based on the similarity matrices of ISSR-PCR banding patterns resulted with ten random primers, showed that the selected groups of the 1 st and 2 nd generations were the most similar and clustered together forming a distinct group that in turn cluster with nonselected laboratory group that in turn cluster with parent group (field, non-selected), while the 3 rd