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.

The geographic understanding of snail borne disease in endemic areas using satellite surveillance

The current status of research on use of earth observing satellite sensors and geographic ifnormation systems for control program management of schistosomiais and fascioliasis is reviewed.

Gender-role alternation in the simultaneously hermaphroditic freshwater snail Physa acuta: not with the same partner

In simultaneous hermaphrodites, gender conflicts that arise from two potential mates sharing the same gender preference may be solved through conditional reciprocity (or gamete trading). Conditional reciprocity had initially been considered widespread, but recent studies suggest that its real occurrence may have been overestimated, possibly because most mating observations have been performed on isolated pairs of individuals. Some resulting patterns (e. g., non-random alternation of sexual roles) were indeed compatible with conditional reciprocity but could also have stemmed from the two partners independently executing their own mating strategy and being experimentally enforced to do so with the same partner. Non-random alternation of gender roles was recently documented in the simultaneously hermaphroditic freshwater snail Physa acuta. To distinguish between conditional and unconditional gender alternations, we observed copulations of individually marked snails reared at three contrasted densities. We showed that density affected the overall frequency of copulations during the first 2 days of the experiment with high-density boxes showing more copulations than low density boxes, but it did not affect gender alternation patterns. A change in gender role was observed more often than expected by chance over two successive copulations by the same individual, confirming previous studies. However, gender switches did not preferentially occur with the same partner. We conclude that gender alternation is not due to conditional reciprocity in P. acuta. It may rather stem from each individual having a preference for gender alternation. We finally discuss the mechanisms and the potential extent of this unconditional reciprocity.

Freshwater snails and schistosomiasis mansoni in the State of Rio de Janeiro, Brazil: I - metropolitan mesoregion

In order to elaborate a planorbid chart of the State of Rio de Janeiro a survey of freshwater gastropods in the Metropolitan Mesoregion of this State was performed and revealed the occurrence of 20 species: Antillorbis nordestensis (Lucena, 1954); Biomphalaria glabrata (Say, 1818); Biomphalaria schrammi (Crosse, 1864); Biomphalaria straminea (Dunker, 1848); Biomphalaria tenagophila (Orbigny, 1835); Burnupia sp.; Drepanotrema anatinum (Orbigny, 1835); Drepanotrema cimex (Moricand, 1839); Drepanotrema lucidum (Pfeiffer, 1839); Ferrissia sp.; Gundlachia ticaga (Marcus & Marcus, 1962); Heleobia davisi Silva & Thomé, 1985; Lymnaea columella Say, 1817; Melanoides tuberculatus (Müller, 1774); Physa cubensis Pfeiffer, 1839; Physa marmorata Guilding, 1828; Pomacea sp.; Pomacea canaliculata (Lamarck, 1822); Pomacea lineata (Spix, 1827) and Pomacea sordida (Swainson, 1823). Among the planorbid species B. tenagophila was the most frequent, occurring in all municipalities surveyed. The present study extends the distribution of B. straminea in the State of Rio de Janeiro and reports new records for A. nordestensis, B. schrammi, G. ticaga, H. davisi and the genera Burnupia and Ferrissia. An account about the current transmission areas of schistosomiasis mansoni in this Mesoregion is presented as well.

Planorbidae, Lymnaeidae and Physidae of Peru (Mollusca: Basommatophora)

In the course of several trips to Peru I had the opportunity of collecting topotypic specimens of Biomphalaria andecola (Orbigny, 1835), B. helophila (Orbigny, 1835), B. pucaraensis (Preston, 1909), Drepanotrema limayanum (Lesson, 1830), D. kermatoides (Orbigny, 1835), and Lymnaea viatrix Orbigny, 1835, besides B. tenagophila (Orbigny, 1835), Helisoma trivolvis (Say, 1817), H. duryi (Wetherby, 1879), Physa acuta Draparnaud, 1801, and seemingly P. peruviana Gray, 1828. B. pucaraensis is considered a junior synonym of B. peregrina (Orbigny, 1835).

Freshwater snails and Schistosomiasis mansoni in the state of Rio de Janeiro, Brazil: IV - Sul Fluminense Mesoregion

In this paper, the forth of a series dealing with the survey of freshwater gastropods of the state of Rio de Janeiro, the results of collections carried out in the Sul Fluminense Mesoregion from 2000 to 2002 are presented and revealed the occurrence of 18 species: Antillorbis nordestensis; Biomphalaria glabrata; Biomphalaria peregrina; Biomphalaria straminea; Biomphalaria tenagophila; Drepanotrema anatinum; Drepanotrema cimex; Drepanotrema lucidum; Ferrissia sp.; Gundlachia ticaga; Gundlachia sp.; Heleobia sp.; Lymnaea columella; Melanoides tuberculatus; Physa acuta; Physa marmorata; Pomacea sordida and Pomacea sp. As to the snail hosts of Schistosoma mansoni the most frequent species was B. tenagophila, found in all municipalities surveyed, except Parati. Besides new records the present study extends the distribution of B. peregrina and B. straminea in the state. No specimens were found harbouring larval forms of S. mansoni although different kinds of cercariae had been observed. An account about the current schistosomiasis transmission sites in this Mesoregion is presented as well.

Planorbidae, Lymnaeidae and Physidae of Ecuador (Mollusca: Basommatophora)

In the course of a trip to Ecuador I had the opportunity of collecting topotypic specimens of the following nominal species of pulmonate molluscs: Biomphalaria cousini Paraense, 1966; Planorbis equatorius Cousin, 1887; P. canonicus Cousin, 1887; Lymnaea cousini Jousseaume, 1887 and P. boetzkesi Miller, 1879. Additional findings were: Helisoma trivolvis (Say, 1817), Biomphalaria peregrina (Orbigny 1835), Drepanotrema anatinum (Orbigny, 1835), D. kermatoides (Orbigny, 1835), D. lucidum (Pfeiffer, 1839), D. surinamense (Clessin, 1884), Lymnaea columella Say, 1817 and Physa acuta Draparnaud, 1805. P. boetzkesi and P. canonicus are considered junior synonyms of Gyraulus hindsianus (Dunker, 1848) and Biomphalaria peregrina (Orbigny, 1835), respectively.

Freshwater snails and schistosomiasis mansoni in the state of Rio de Janeiro, Brazil: V - Norte fluminense mesoregion

In this paper, the fifth of a series dealing with the survey of freshwater gastropods of the state of Rio de Janeiro, the results of collections carried out in the Norte Fluminense Mesoregion from 2002 to 2003 are presented and revealed the occurrence of 19 species: Antillorbis nordestensis; Burnupia sp.; Biomphalaria tenagophila; Drepanotrema anatinum; Drepanotrema cimex; Drepanotrema depressissimum; Drepanotrema lucidum; Ferrissia sp.; Gundlachia ticaga; Gundlachia sp.; Heleobia sp.; Hebetancylus moricandi; Idiopyrgus sp.; Lymnaea columella; Melanoides tuberculatus; Physa acuta; Physa marmorata; Pomacea sordida, and Pomacea sp. Concerning the snail hosts of Schistosoma mansoni only B. tenagophila was found, in contrast with other previuosly studied mesoregions.No specimens were found harbouring larval forms of S. mansoni although different kinds of cercariae had been observed.An account about the current schistosomiasis transmission sites in this Mesoregion is presented as well.

Planorbidae, Lymnaeidae and Physidae of Argentina (Mollusca: Basommatophora)

In the course of several trips to Argentina I had the opportunity of collecting specimens of Acrorbis petricola Odhner,1937, Biomphalaria orbignyi Paraense, 1975, B. peregrina (Orbigny, 1835), B. tenagophila (Orbigny, 1835) Lymnaea viatrix Orbigny, 1835, Antillorbis nordestensis (Lucena, 1954), B. intermedia (Paraense & Deslandes, 1962), B. oligoza Paraense, 1974, B. straminea (Dunker, 1848), Drepanotrema anatinum (Orbigny, 1835), D. cimex (Moricand, 1837), D. depressissimum (Moricand, 1837), D. heloicum (Orbigny, 1835), D. kermatoides (Orbigny, 1835), D. lucidum (Pfeiffer, 1839), L. columella Say, 1817, Physa acuta Draparnaud, 1805, and P. marmorata Guilding, 1828.

Anatomical studies of sibling species within neotropical lymnaeids, snail intermediate hosts of fascioliasis

Several anatomical parameters of the reproductive system have been used to distinguish Lymnaea cubensis from L. viatrix, the snail hosts of fascioliasis in South America and the Caribbean area. Three samples have been collected in the type localities of L. cubensis (Cuba), L. viatrix var. A ventricosa (Argentina, Río Negro Lower Valley), and L. viatrix var. B elongata (Peru, Lima), respectively. Only one parameter, the relative lengths of the penis sheath and preputium, showed significant differences between L. viatrix var. ventricosa and the two other taxa. None of the studied parameters separated L. cubensis from L. viatrix var. elongata.

Freshwater snails and schistosomiasis mansoni in the state of Rio de Janeiro, Brazil: VI - Noroeste Fluminense Mesoregion

In this paper, the last of a series dealing with the survey of freshwater gastropods of the state of Rio de Janeiro, the results of collections carried out in the Noroeste Fluminense Mesoregion from 2002 to 2005 are presented and revealed the occurrence of 20 species: Antillorbis nordestensis; Biomphalaria glabrata; B. straminea; B. tenagophila; Drepanotrema anatinum; D. cimex; D. depressissimum; D. lucidum; Ferrissia sp.; Gundlachia ticaga; Gundlachia sp.; Heleobia sp.; Idiopyrgus sp.; Lymnaea columella; Melanoides tuberculatus; Physa acuta; P. marmorata; Plesiophysa guadeloupensis; Pomacea lineata; and Pomacea sp. Concerning the snail hosts of schistosomiasis the three natural vectors were identified and, although no specimens were found harbouring larval forms of Schistosoma mansoni, different kinds of cercariae had been observed.

Distribution of Lymnaeidae (Mollusca: Pulmonata), intermediate snail hosts of Fasciola hepatica in Venezuela

An extensive malacological survey was carried out between 2005-2009 in order to clarify the exact number of lymnaeid species which may be intermediate hosts of Fasciola hepatica in Venezuela. Four species were discovered during this survey, including two local species: Lymnaea cubensis and Lymnaea cousini and two exotic species: Lymnaea truncatula and Lymnaea columella. The most common local species was L. cubensis which was found at 16 out of the 298 sampling sites. This species has a large distribution area throughout the Northern part of Venezuela and was encountered from sea level to an altitude of 1,802 m in state of Trujillo. The second local species L. cousini was collected at only two sites of the Andean Region at altitudes of 3,550 m and 4,040 m, respectively. The European L. truncatula was found at 24 sites all located in the states of Mérida and Táchira at an altitude varying between 1,540-4,000 m. The respective distribution areas of L. cubensis and L. truncatula do not appear to overlap, but more detailed malacological surveys are needed. The fourth lymnaeid species, L. columella was collected in a canal from Mérida at an altitude of 1,929 m and in an irrigation canal from the state of Guárico, at an altitude of 63 m. The role of these four lymnaeid species in the transmission of fascioliasis in Venezuela is discussed.

Les paramètres du cycle vital de Physa acuta (Gastropoda, Mollusca) en milieu expérimental.

The values of the life history parameters expressed in the Lotka's equation were measured in the experimental conditions (20ºC, food ad libitum) for the aquatic pumonate Physa acuta. The estimated fitness value allows the population to double in about 4 weeks. The life cycle is very short (about 3 times shorter than for Lymnaea peregra in similar conditions) because of the important relative size of the eggs, a very high growth rate and an early maturity. This kind of strategy seems adaptive in eutrophic and temporary pools, where the adult mortality is important and density-independant. While the longevity shows very poor correlations with all other parameters, adult size, age at maturity and fecundity are strongly correlated. Structural and functionnal interpetations of these correlations are proposed. A mixed strategy seems a good hypothesis for this usually bivoltine species: the little-size, early-maturity and high-fecondity strategy may be selected during the summer, and the big-size, delayed-maturity and poor fecundity strategy during the winter

Comunicação Cientifica - Distribuição Geopolítica da Fasciolose Hepática na Ilha de Santiago, Cabo Verde

O trabalho foi realizado no intuito de registrar a distribuição geopolítica da Fasciolose Hepática na Ilha de Santiago, Cabo Verde. Durante a avaliação, realizada de maio a junho de 2008, foram registrados tamanho e taxas de infecção do molusco, pH e temperatura da água e taxas de infecção de vertebrados. As amostras de moluscos e de fezes de bovinos foram coletadas, de forma aleatória, em todos os municípios da Ilha de Santiago, com exceção de Tarrafal, e, devidamente embaladas, encaminhadas para o Laboratório do Instituto Nacional de Investigação e Desenvolvimento Agrário (INIDA), onde foram analisadas. As análises demonstraram resultados positivos para a coproscopia de bovinos e a presença do hospedeiro intermediário (Lymnaea natalensis) em todos os municípios visitados. Também ficou demonstrada uma correlação positiva entre a taxa de infecção dos hospedeiros vertebrados e invertebrados, sendo que o maior índice foi registrado no Município de Santa Cruz (72,72%) e o menor no da Praia (16,66%). A taxa de infecção média verificada para os moluscos e os bovinos foi de 51,51% e 37,15%, respectivamente.

Molluscicidal activity of Nerium indicum bark

The molluscicidal activity of Nerium indicum bark against Lymnaea acuminata snails was studied. The toxicity of different bark preparations was both time and dose dependent. The 24-h LC50 of the lyophilized aqueous extract of bark was 34.5 mg/l whereas that of lyophilized boiled water extract was 42.5 mg/l. Low concentrations of vacuum-dried ethanolic extract (24-h LC50: 4.9 mg/l) and purified bark (24-h LC50: 0.87 mg/l) were effective in killing the test snails.