Biomphalaria Straminea Research Articles

Effects of Bayluscide WP 70 on the survival and water-leaving behaviour of Biomphalaria straminea, snail host of schistosomiasis in northeast Brazil.

The toxic and behavioural effects of niclosamide (Bayluscide WP 70) on Biomphalaria straminea from a highly endemic area of schistosomiasis in northeastern Brazil were investigated through laboratory bioassays. The LD50 and LD90 were 0.114 mg/l and 0.212 mg/l, respectively. Water-leaving behaviour occurred among 14% to 30% of the snails in the presence of sublethal doses of niclosamide and among 16% of the controls. It was concluded that both the relatively low susceptibility to niclosamide and water-leaving behaviour of local B. straminea may be responsible for the recolonization of transmission foci after mollusciciding. It was suggested that recently improved measures of snail control, such as controlled-release formulations of niclosamide and plant molluscicides should be considered in areas where snail control is recommended.

Fecundity changes induced by low-doses of gamma radiation on Biomphalaria straminea (Dunker, 1848).

A population of 420 snails Biomphalaria straminea, an intermediate host of Schistosoma mansoni, received gamma-rays obtained from a 60Co source in low-doses (0/2,5/5/7,5/10/15/20 and 25 Gy); half population was kept in colonies (allowing cross fertilization) and the other half was maintained in sexual isolation (allowing self fertilization). Results showed that 15 Gy stimulates the fertility of both groups but the colonies were more sensitive and at this dose its fertility overpasses the control group dose. The possible hormonal role played in the observed phenomena is under investigation.

Occurrence of Biomphalaria tenagophila and disappearance of Biomphalaria straminea in Paracambi, RJ, Brazil.

Occurrence of Biomphalaria tenagophila and disappearance of Biomphalaria straminea in Paracambi, RJ, Brazil.

Schistosomiasis: new occurrence of Biomphalaria straminea in Belo Horizonte, Minas Gerais

In Belo Horizonte, Minas Gerais, Brazil, the snail Biomphalaria straminea was found in the Pampulha region. Recently the snail was found in ditches in the old Santa Lúcia Reservoir, a now-extinct focus of schistosomiasis transmission by B. glabrata. The snails were collected and examined to verify whether they were naturally infected with Schistosoma mansoni. Negative specimens were used for breeding or infection with the LE strain of S. mansoni from the laboratory and another strain obtained from eggs found in the feces of a schoolchild (VGS) from Belo Horizonte. Among the 1890 snails collected from 1994 to 1995, none were infected with S. mansoni. Among 87 snails collected and exposed to the LE strain, 9 (10.3%) shed cercariae; among 83 snails from F1, and exposed to LE, 10 (12.0%) shed cercariae. Among 88 snails exposed to VGS, 10 (11.3%) shed cercariae. In Belo Horizonte, schistosomiasis is transmitted by B. glabrata and B. tenagophila. However, currently there exists the risk of appearance of a focus in which B. straminea could be the host if prophylactic measures are not taken by the authorities responsible for the construction of a park and lake at that site.

INBREEDING DEPRESSION, NEUTRAL POLYMORPHISM, AND COPULATORY BEHAVIOR IN FRESHWATER SNAILS: A SELF-FERTILIZATION SYNDROME.

This paper examines the consequences of self-fertilization on life-history traits and neutral genetic polymorphism in natural populations of three species of hermaphrodite freshwater snails: Biomphalaria straminea, Bulinus globosus, and the aphallic species Bulinus truncatus. Life-history traits (fecundity, growth, hatching rate, and survival of offspring) are compared under laboratory conditions between isolated (obligatory selfing) and paired (outcrossing possible) snails in one population of B. straminea and B. globosus and two populations of B. truncatus. The genetic polymorphism of the same four populations is analyzed using electrophoretic markers in B. straminea and B. globosus and microsatellite markers in B. truncatus. In B. truncatus and B. straminea, isolated snails have a higher fecundity than paired snails, whereas the contrary is observed in B. globosus. For all populations, no difference in hatching rate and offspring survival is detected between the two treatments. Genetic analyses using microsatellite markers conducted in B. truncatus on progeny of paired snails reveal a high selfing rate in spite of high copulation rates, highlighting the difficulties of obtaining outcrossing in highly selfing snails. The high survival of selfed offspring in B. truncatus and B. straminea indicates that inbreeding depression is limited. The extent of inbreeding depression in B. globosus is less clear. Overall, fitness decrease in this species is limited to fecundity. The extent of allozyme polymorphism is very limited whereas a much higher variability is observed with microsatellites. Biomphalaria straminea and B. truncatus populations are also characterized by very low observed heterozygosities and large heterozygote deficiencies, whereas the B. globosus population does not exhibit such a deficiency. Overall these results allow the definition of a self-fertilization syndrome in hermaphrodite freshwater snails: selfing populations (such as those of B. straminea and B. truncatus studied here) are characterized by high selfing rates in spite of copulations, limited deleterious effects of selfing, limited neutral genetic polymorphism, and large heterozygote deficiencies.

Distribution of Biomphalaria straminae in the southern neotropical region of Brazil

A careful anatomical revision of 10,616 preserved specimens of snails from 76 localities of the State of S. Paulo, Brazil, was made with a view better to determining the geographical distribution of Biomphalaria straminea in the Neotropical Region of Southern Brazil. The analysis has shown that previous determinations were correct. The study was then complemented with a survey of information from the literature about distribution of the species. The distribution pattern of the species has expanded greatly over the last few years, perhaps an account of the construction of new dams, and the navigation system in the upper Paraná Basin. Epidemiological data have shown that B. straminea is a good host to S. mansoni. Continuous schistosomiasis control must be exercised so as to prevent the further expansion of the disease.

Introduction and spreading of Biomphalaria straminea (Dunker, 1848) (Mollusca: Pulmonata: Planorbidae) in Guadeloupe, French West Indies

The finding in 1985 of a well-established population of Biomphalaria straminea in a pond in Grande Terre of Guadeloupe constitutes a new species record for the freshwater molluscan fauna of that island. The following years a rapid extension of the species was documented on Grande Terre and Marie Galante. However, it was never found in the neighboring island of Basse Terre. The invasion of the whole hydrographic system of this island by Melanoides tuberculata during the last decade and the current presence of well-established and dense populations of this snail may explain the failure of the colonization by B. straminea.

Levantamento planorbídico do Estado de São Paulo: 8ª Região Administrativa (grande área de São José do Rio Preto)

In order to know the distributional patterns of Basommatophoran snails in the state of São Paulo (Brazil), 85 "counties" in the area of S. José do Rio Preto were worked out during seven months (1982). Snails from 286 breeding places were collected and identified. Biomphalaria straminea, an intermediate host of S. mansoni, was found in four little ponds, in the neighbourhood of Altair and S. José do Rio Preto. It was concluded that schistosomiasis has little chance to spread out in the studied area.

First register of Biomphalaria straminea Dunker, 1848, in Santa Catarina State

The first register of Biomphalaria straminea, vector species of schistosomiasis, in Santa Catarina State, South Brazil is described. The specimens were obtained from two ornamental aquaria of private residences. In both cases the ornamental plants and/or fishes were bought from the same supplier. The presence of this species was later confirmed in the farm where these plants and fishes are cultivated, in the city of Governador Celso Ramos, also in Santa Catarina State. The occurrence in natural environments was later detected in two different places of the Island of Santa Catarina.

Moluscos límnicos de uma área do Alto Araguaia (Brasil)

An analysis was carried out to determine the natural population of freshwater molluscs from 5 municipalities within the area of influence of the Couto Magalhães hydroelectric project. These municipalities cover a large area of the State of Goiás and Mato Grosso do Sul (Brazil). In this study 624 molluscs of the following species were examined: Drepanotrema anatinum, D. lucidum, D. depressissimum, Biomphalaria straminea, D. schrammi, Physa marmorata, Lymnaea columella, Pomacea and Eupera. One to their importance in public health, the discovery of Biomphalaria straminea and Lymnaea columella, intermediate hosts, respectively, of Shistosoma mansoni and Fasciola hepatica, deserves special mention.

Selection of gastropod prey by a tropical freshwater crab

Prey selection by Somaniathelphusa sinensis (Parathelphusidae) among five gastropod species (two prosobranchs, three pulmonates) was associated with two snail attributes. First, the degree of defence of the tissues by the shell, approximated by shell weight (SW)/tissue dry weight (M). Snails with the heaviest shells (Sinotaia quadrata: Viviparidae) could not be attacked successfully by any crabs, and those with somewhat lighter shells (Melanoides tuberculata: Thiaridae) were protected from small crabs. Secondly, among those light‐shelled snails which could be attacked successfully, prey value (M/handling time, Ht) determined rank order of preference. Biomphalaria straminea (Planorbidae), with the highest M/Ht, was the species most readily eaten. When presented with a single snail species, crabs selected among different‐sized B. straminea in a way which maximized M/Ht. This preference was most strongly exhibited by small crabs. A lack of size selection for Radix plicatulus (Lymnaeidae) prey was in agreement with an absence of a clear influence of size on Ht for this species. Manipulation of M/Ht by attaching plastic discs to B. straminea shells (thereby increasing Ht) resulted in patterns of prey selection in accordance with the hypothesis that foraging S. sinensis maximized M/H1.Partial consumption of R. plicatulus, and to a lesser degree Physella acuta (Physidae), was common when groups of snails were presented to individual crabs, and occurred more frequently when large snails were offered. Partial consumption and subsequent rejection of large snails may have masked selection for small prey which were rarely abandoned before being completely eaten.The implications of patterns of prey selection were discussed with reference to the influence of crab predation on snail distribution and abundance in Hong Kong fresh waters.

DISTRIBUTION OF THE SCHISTOSOME VECTOR SNAIL, BIOMPHALARIA STRAMINEA (PULMONATA: PLANORBIDAE) IN HONG KONG

Biomphalaria straminea (Dunker) is a snail intermediate host of Schistosoma mansoni Sambon which has invaded Hong Kong in recent years from its home range in Brazil. This study examines its distribution pattern in terms of habitat type and hydrological factors. The data revealed very strong colonizing power, both in terms of number of sites occupied as well as numerical dominance at these sites. An inability to colonize lotic habitats may have been related to low levels of dissolved minerals and nutrients but the effect of current speed on colonization has yet to be resolved. Principal component analysis revealed that hydrological factors important for colonization included high levels of dissolved calcium, magnesium, iron, chloride, total nitrogen, sulphate and phosphate. pH had only a secondary effect. The significance of these findings is discussed with special reference to the likelihood of introduction of B. straminea elsewhere, and possible management strategies.

Biomphalaria kuhniana (Clessin, 1883), planorbid mollusc from South America

The validity of Biomphalaria kuhniana (Clessin, 1883) is confirmed through morphological study of specimens from Surinam (type locality) and the area of Tucurui (Tocantins river, state of Pará, Brazil) in comparison with B. straminea (Dunker, 1848), and throught crossing experiments which revealed complete reproductive isolation between the two species. The full-grown shell of kuhniana is smaller (about 7.5 mm) than that of straminea (11 mm to 16.5 mm). Anatomically they differ in the degree of corrugation of the vaginal wall (little developed in kuhniana, conspicuous in straminea), number and shape of prostatic diverticula (kuhniana 4 to 9, shorter and less branched; straminea 9 to 18, longer and more branched),number of muscle layers at the middle of the penis (two in kuhniana, three in straminea), distal segment of the spermiduct usually straight or slightly wavy in kuhniana, more or less curly in straminea. Differences between B. kuhniana and B. intermedia (paraense & Deslandes, 1962) are less marked. The latter has a shell up to about 12 mm in diameter, 7 to 15 prostatic diverticula, two muscle layers at the middle of the penis, and a vaginal wall with a combination of a more or less developed corrugation (or sometimes a mere swelling) on the left of the spermathecal duct and a rudimentary pouch on the right of the duct. A Biomphalaria straminea complex is proposed to include that species as well as B. kuhniana and B. intermedia.

Observações ecológicas sobre Biomphalaria straminea (Dunker, 1848) em áreas do Nordeste, Brasil

The different climatic regions determine the zoogeographic distribution of various animal species depending on their particular conditions and ecological preferences. The host schistosomiasis planorbid is one of these species. This paper deals with the distribution of Biomphalaria straminea in northeast Brazil. It starts from the analysis of different climatic peculiarities in this region, associated to limnological observation done by the author in three different hydric collections in the state of Sergipe. It has been concluded that this is an "eurióioca" species. Its broad ecological valence permits this species to survive in regions where climate asperties are evident, requiring behavior and physiological adaptations. The species survives in all northeast region, from "zona da mata", in the coast, to the semi-arid "sertão".

Orientation of the snail Biomphalaria straminea (Dunker, 1848) in response to light in a situation of selection.

The behavioral response of Biomphalaria straminea to light was evaluated in terms of location of the snail in a Y-shaped aquarium in a situation of selection and of the rate (cm/hour) and direction of locomotion under homogeneous (vertical) or differential (horizontal) lighting upon only one arm of the aquarium. The light source consisted of daylight fluorescent lamps with a spectrum close to that of natural light, with illumination varying from 2.8 to 350 lux. Analysis of the data showed that all animals, whether in groups or isolated, were attracted to light, although the time needed to approach the light source was 50% shorter for the former than for the latter. The rate of locomotion of B. straminea was 35% higher than that observed in B. glabrata and 51% higher than that observed in B. tenagophila studied under similar conditions. The results are discussed in terms of social factors and geographical distribution of the three species.

Experimental infection with Schistosoma mansoni of Biomphalaria straminea from different parts of the Northeast of Brazil.

In the western part of the State of Bahia Biomphalaria straminea and B. glabrata both occur, but in the majority of cases they do not share the same habitat. In the State of Ceará, however, B. straminea is the sole snail host of Schistosoma mansoni. In this survey, no naturally infected B. straminea was found among snails collected from Bahia and Ceará, evidently because of the very low infection rates. The susceptibility of laboratory-reared specimens to infection with a Puerto Rican strain of S. mansoni was then tested experimentally. In general, the snails showed very low susceptibility. The infection rates were 1.1% among snails from Redenção (Ceará); 2.3% in those from Pentecoste (Ceará); 2.9% in snails from São Desidério (Bahia), while they were very high among an albino strain (NIH) of B. glabrata used as control. Another group of B. straminea from São Desidério was exposed to a Bahian strain of S. mansoni and the infection rate was still very low (3.6%) Apparently, the very low susceptibility of B. straminea, despite high snail density, is correlated with moderate infection rates with S. mansoni among humans, as shown by the results of stool examinations conducted by SUCAM in the municipalities of Redenção and Pentecoste, in Ceará.

Biomphalaria straminea and other planorbids in the Dominican Republic

In addition to previous records of Biomphalaria glabrata in the Dominican Republic, the southern central communities of Haina Arriba and Boca Chica, in the National District, are reported as new localities for that species; other species collected were Biomphalaria obstructa, B. helophila, Drepanotrema lucidum and Lymnaea viatrix. Biomphalaria straminea, a potential vector of Schistosoma mansoni, was found for the first time in the country, in the River Iguamo, just outside of the community of San Pedro de Macorís.

Potential of the Biomphalaria straminea populations of the State of Minas Gerais as hosts of Schistosoma mansoni

Caramujos de Biomphalaria straminea, descendentes de exemplares coletados em nove municípios do Estado de Minas Gerais, foram infectados experimentalmente com três cepas de Schistosoma mansoni: "LE", procedente de Belo Horizonte (MG); "SJ", procedente de São José dos Campos (SP) e "AL" procedente do Nordeste (AL). As taxas de infeção variaram de 0,0 a 24,0% com a cepa "LE"; de 0,0 a 16% com a cepa "SJ" e de 2,0 a 9,0% com a cepa "AL". Os índices de infecção experimental obtidos foram semelhantes aos registrados por outros autores, para B. straminea dessa região. Comparou-se o número de cercárias de cepa "LE", eliminadas por oito exemplares de B. straminea de Baldim e oito Biomphalaria glabrata do controle, após 30 minutos de exposição à luz. O número de cercárias eliminadas por B. straminea foi de 4.550, aproximadamente cinco vezes menor que o de B. glabrata, 22.679. Discute-se a potencialidade desses moluscos como hospedeiros do S. mansoni nessa região.

The life cycle of Dendritobilharzia anatinarum cheatum, 1941 (Trematoda, Schistosomatidae)

The life cycle of Dendritobilharzia anatinarum was completed experimentally in the laboratory. Cairina moschata domestica (domestic duck) and Biomphalaria straminea served respectively as definitive and intermediate hosts. Eggs passed in duck faeces hatch miracidia in 10 minutes when placed in water. Eight days after the snail infection, the mother sporocyst contains daughter sporocysts ready to migrate. Cercariae are present within the daughter sporocysts 23 days after infection and emerge from the snail on the 25th day. They actively penetrate the skin of the duck and after a prepatent of 39 days, sexually mature trematodes are present in the blood vessels of the bird. The adult parasite is predominantly in the renal-portal system and to a lesser degree in the lungs and mesentery. A detailed morphological description of the egg. miracidium, sporocyst and cercaria is presented.

Moluscos vectores da esquistossomose mansônica no lado leste do Rio São Francisco, no Estado da Bahia

Pela primeira vez foi realizado um levantamento malacológico de espécies vectoras de Schistosoma mansoni na região do lado Oeste do Rio São Francisco, no Estado da Bahia. Observou-se que nas áreas onde a única espécie encontrada foi B. straminea, a esquistossomose não constitui um problema médico. Entretanto, nas áreas onde foi coletado B. glabraata, além de B. straminea, a esquistossomose se apresenta com características de alta endemicidade. A ausência de moluscos, apesar da abundância de água, foi observada em extensas áreas, quase despovoadas. Esse quadro poderá se modificar em futuro bem próximo, devido â construção de novas estradas, bem como pela implantação de projetos de irrigação. Baseados nos presentes resultados e, em dados da literatura, os autores correlacionam a distribuição geográfica das espécies vectoras com a endemicidade da esquistossomose no Brasil.