Biomphalaria Tenagophila Research Articles

Schistosomiasis mansoni in Bananal (State of São Paulo, Brazil): II. Intermediate hosts.

We conducted monthly snail captures in Bananal, State of São Paulo, Brazil, between March 1998 and February 2001, to identify Schistosoma mansoni vectors, estimate seasonal population changes, and delimit foci. We also evaluated the impact of improvements in city water supply and basic sanitation facilities. We identified 28,651 vector specimens, 28,438 as Biomphalaria tenagophila, 49 of them (0.2%) infected with S. mansoni, and 213 as B. straminea, none of the latter infected. Vectors predominated in water bodies having some vegetation along their banks. Neither population density nor local vegetation could be linked to vector infection. We found the first infected snails in 1998 (from March to May). Further captures of infected snails ocurred, without exception, from July to December, when rainfall was least. Irrespective of season, overall temperature ranged from 16.5 degrees C to 21 degrees C; pH values, from 6.0 to 6.8. Neither factor was associated with snail population density. Frequent contact of people with the river result from wading across it, extracting sand from its bottom, fishing, washing animals, etc. Despite a marked reduction in contamination, cercaria shedding persists. Whatever the location along its urban course, contact with river Bananal, particularly of the unprotected skin, entails risks of infection.

Freshwater snails and Schistosomiasis mansoni in the state of Rio de Janeiro, Brazil: III--Baixadas Mesoregion.

In this paper, the third 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 Mesoregion Baixadas from 2000 to 2002 are presented. Twenty-two species, belonging to seven families, were found. As to the snail intermediate hosts of Schistosoma mansoni, the most frequent species was Biomphalaria tenagophila besides some new findings of Biomphalaria straminea. No specimens were found harboring larval forms of S. mansoni although different kinds of cercariae had been observed.

Schistosomiasis mansoni and distribution of freshwater mollusks in natural bodies of water in Niterói, Rio de Janeiro State, Brazil

The authors report on the distribution of freshwater mollusks in Niterói, Rio de Janeiro State, Brazil, and notification of schistosomiasis cases in this municipality from 1995 to 2000. All breeding sites favorable to freshwater mollusks were surveyed, showing the following species: Antillorbis nordestensis (Lucena, 1954), Biomphalaria straminea (Dunker, 1848), Biomphalaria tenagophila (Orbigny, 1835), Drepanotrema anatinum (Orbigny, 1835), Lymnaea columella Say, 1817, Melanoides tuberculatus (Müller, 1774), Physa cubensis Pfeiffer, 1839, Physa marmorata Guilding, 1828, and Pomacea sordida (Swainson, 1823). Some 3,691 specimens of snail hosts for Schistosoma mansoni Sambon, 1907 were examined by exposure to artificial light and crushing. No S. mansoni cercariae were found, although other types of cercariae were observed.

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.

Biomphalaria tenagophila (Orbigny, 1835) (Mollusca): adaptation to desiccation and susceptibility to infection with Schistosoma mansoni Sambon, 1907.

Experiments were carried out to test the susceptibility of Biomphalaria tenagophila to the infection with strain SJ of Schistosoma mansoni in the F1, F2 and non-selected parental generation. The potential adaptation of B. tenagophila to desiccation, in healthy mollusks and those exposed to the larvae of S. mansoni of the F1, F2 and non-selected parental generations was also studied. The presence of mucus and soil, at the shell opening, protected the snails against desiccation, favoring survival. The healthy mollusks performed more attempts against desiccation than those exposed to the larvae of the parasite. The mortality rate, during desiccation, was higher among mollusks that remained buried and with the shell opening unobstructed. During the desiccation period the stage of development of the parasite was influenced by the weight loss and the survival of the snails. The longer the period of desiccation, the greater was the weight loss observed, abbreviating survival. The non-selected parental generation was more sensitive to desiccation than the F1 and F2 generations, both in healthy mollusks and in those exposed to S. mansoni larvae. Healthy mollusks were more resistant to desiccation than those exposed to the larvae of the S. mansoni. Desiccation did not interrupt the development of S. mansoni larvae in mollusks, causing a delay in the cercariae elimination. The susceptibility of B. tenagophila to the SJ strain of S. mansoni, in mollusks maintained in water during the larvae incubation period, was similar in all three generations.

Freshwater snails and Schistosomiasis mansoni in the State of Rio de Janeiro, Brazil: II--Centro Fluminense Mesoregion.

During the course of a survey carried out from 2000 to 2001 in the Centro Fluminense Mesoregion of the State of Rio de Janeiro 22 molluscan species were found. Many of the records are new due to the dearth of previous studies. Concerning the snail hosts of Schistosoma mansoni, the most frequently encountered species was Biomphalaria tenagophila, as it occurred in all the surveyed municipalities. There are new records of Biomphalaria straminea and Biomphalaria peregrina which is regarded as a potential intermediate host. Drepanotrema lucidum and Antillorbis nordestensis were found to be shedding echinostome cercariae and strigid cercariae respectively. An account about the current schistosomiasis transmission sites in this Mesoregion is presented as well.

Formas larvais de Trematoda provenientes de gastrópodes límnicos da microrregião Rio de Janeiro, sudeste do Brasil

The study of freshwater molluscs associated with helminth larval stages from the state of Rio de Janeiro revealed different morphological types of cercariae. Among them, Pleurolophocercus cercaria, Echinostomocercaria, Strigeocercaria, and Xiphidiocercaria, were found in Biomphalaria tenagophila (Orbigny, 1835), Physa marmorata Guilding, 1828 and Melanoides tuberculatus (Müller, 1774). For the later species is the first occurrence as an intermediate host for tremadodes in Brazil and the first record of Pleurolophocercus cercaria in Brazil.

Effects of the desiccation on Biomphalaria tenagophila (Orbigny, 1835) (Mollusca) infected by Schistosoma mansoni Sambon, 1907

Specimens of Biomphalaria tenagophila exposed to miracidia of Schistosoma mansoni were submitted to different desiccation periods as follows: group I: 24 h after exposure, desiccated for 28 days; group II: after cercariae elimination, desiccated for 7 days; group III: 21 days after exposure, desiccated for 7 days; group IV: 14 days after exposure, desiccated for 14 days; group V: 7 days after exposure, desiccated for 21 days. From the obtained data it was verified that desiccation was not capable of interrupting the development of larvae of S. mansoni in mollusks. A delay in the development of S. mansoni larvae in groups I, III, IV and V was observed. A pause was verified in the development of S. mansoni larvae in groups II, III, IV and V. Some larvae, in groups I, III, IV and V, did not suffer as a result of desiccation and continued their development. Larvae in the cercariae stage were shown to be more sensitive to desiccation. It was possible to obtain clearing of mollusks infected by sporocysts II and cercariae using a period of 7 days of desiccation.

Estudios morfométricos y biológicos de xifidiocercarias (Trematoda) provenientes de la infección natural de Lymnaea columella Say, 1817 (Basommatophora, Lymaenidae) y Biomphalaria tenagophila Orbigny, 1835 (Basommatophora, Planorbidae) recolectados en Miracatu, Estado São Paulo, Brasil

Two species of xiphidiocercariae probably belonging to the family Haematoloechidae (Trematoda) emerging from Lymnaea columella (Basommatophora, Lymnaeidae) and Biomphalaria tenagophila (Basommatophora, Planorbidae) collected in Miracatu City, Sao Paulo State, Brazil, between September 1996 and February 1999 were described. The xiphidiocercariae eliminated by L. columella presented a terminal membrane in the tail that morphologicaly differenciated them from those obtained from B. tenagophila. These late xiphidiocercariae were 1.3 times bigger than the former and with the of that ventral sucker bigger than the oral one, while the former presented a sucker size relation inverse. The stylet observed in the xiphidiocercariae eliminated by B. tenagophila oral sucker was shorter than that observed in xiphidiocercariae obtained from L. columella.

Genetic markers from Biomphalaria tenagophila (Gastropoda: Pulmonata: Planorbidae) obtained by the double stringency polymerase chain reaction technique.

Biomphalaria tenagophila, one of the intermediate hosts of the trematoda Schistosoma mansoni, is a simultaneous hermafrodite snail species. In order to analyse the genetic structure of these populations, we performed a double-stringency PCR technique to obtain genetic markers with microsatellites and arbitrary primers in a single reaction.

Búsqueda de xifidiocercarias (Trematoda) en moluscos de agua dulce recolectados en nueve municipios del Estado de São Paulo, Brasil

Xiphidiocercariae, aquatic larval stages of some trematodes are considered a potential instrument for biological control of mosquitoes. In this study we evaluated its natural occurrence in Campinas region and two places in Vale do Ribeira (Registro and Miracatu), São Paulo State. Snails were obtained from fresh water collections from September 1996 to February 1999. The species collected were Lymnaea columella, Physa marmorata, Biomphalaria tenagophila, Biomphalaria sp., Drepanotrema cimex, D. lucidum and Drepanotrema sp. Fasciola hepatica, xiphidiocercariae (Haematoloechidae) and echinostomatid cercariae were detected in the lymnaeids snails from Miracatu, SP. In the same locality were found planorbids snails parasitized by furcocercariae, echinostomatid cercariae and xiphidiocercariae. The xiphidiocercariae found in the planorbids were different from those obtained from lymnaeids. One Biomphalaria sp. infected with furcocercariae was found in Louveira, SP. In the ROSA place (Campinas, SP) an individual of Biomphalaria sp. and one of L. columella were found infected by the furcocercariae and echinostomatid cercariae, respectively. In the place UNI-I, in Campinas, one L. columella was infected by furcocercariae. Double infection in snails from Miracatu was also observed.

Fireflies (Coleoptera: Lampyridae) from Southeastern Brazil: Habitats, Life History, and Bioluminescence

Abstract Observations were made on 26 Brazilian fireflies species of the genera Cratomorphus, Aspisoma, Photinus, Macrolampis, Bicellonychia, Pyrogaster, Photuris, Amydetes, Lamprocera, and Lucidota occurring in the eastern region of Sao Paulo State. These species are adapted to mesophyl tropical forests, secondary growths, marshy areas, and open fields. Cratomorphini larvae were often arboreal and preyed on snails and slugs. Cratomorphus sp2and Aspisoma sp2inhabited marshy areas and their larvae were natural enemies of the aquatic snails Biomphalaria tenagophila Orbigny and Stenophisa columella Say. Photurinae species inhabited marshy areas and humid woody environments and their larvae were always found at ground level. The entire life-cycle of Bicellonychia sp8lasted 11 mo. Most adult fireflies were active for less than 1 h during humid and hot spring evenings, from October to December, although many species were found active during the August–April period. Wave-synchronized bioluminescent signals were ...

Susceptibility of Biomphalaria tenagophila and Biomphalaria straminea to Schistosoma mansoni infection detected by low stringency polymerase chain reaction.

In order to determine Schistosoma mansoni infection rates in Biomphalaria tenagophila and B. straminea, low stringency polymerase chain reaction (LS-PCR) technique was used as a complementary method to light exposure technique. LS-PCR has already been standardized in our laboratory to detect the trematode DNA in B. glabrata. Higher S. mansoni infection rates were detected using conventional method and LS-PCR. The parasite DNA profile was detected in both species after 7-day exposure to miracidia, using LS-PCR. This technique enables early detection of schistosomiasis transmission focuses, in endemic areas, before the beginning of cercariae shedding.

Toxicity of Euphorbia milii Latex and Niclosamide to Snails and Nontarget Aquatic Species

The toxicity of Euphorbia milii molluscicidal latex and niclosamide (NCL) to target snails (Biomphalaria glabrata and Biomphalaria tenagophila) and nontarget aquatic organisms is evaluated. Planorbidae snails were killed by very low concentrations of lyophilized latex (48-h LC50, mg/L: B. glabrata, 0.12; B. tenagophila, 0.09; Helisoma duryi, 0.10). Latex was less toxic (48-h LC50 or EC50, mg/L) to oligochaeta (Tubifex tubifex, 0.31), planktonic crustacea (Daphnia similis, 0.38; C. dubia, 1.07; Artemia sp., 0.93), and fishes (Danio rerio, 0.96; Poecilia reticulata, 1.39), and considerably less toxic to Ampullariidae snails (Pomacea sp., 10.55) and frog tadpoles (Rana catesbeiana, 7.50). Latex (up to 100 mg/L) was not toxic to bacteria (P. putida and V. fischeri), algae (Selenastrum capricornutum and Chlorella vulgaris), and mosquito larvae (Anopheles albitarsis, Aedes aegypti, Aedes fluviatilis). NCL was very toxic (48-h LC50 or EC50, mg/L) to Planorbidae snails (B. glabrata, 0.15, B. tenagophila, 0.13; H. duryi, 0.10), T. tubifex (0.11), crustacea (D. similis, 0.19; Ceriodaphnia dubia, 0.47; Artemia sp. 0.18), fishes (D. rerio, 0.25; P. reticulata, 0.29), R. catesbeiana (0.16), and Pomacea sp. (0.76). NCL was toxic to bacteria, algae (96-h IC50, mg/L: S. capricornutum, 0.34; C. vulgaris, 1.23) and slightly toxic to mosquito larvae. In conclusion, E. milii latex, as compared with the reference molluscicide niclosamide, presents a higher degree of selectivity toward snails which are intermediate hosts of Schistosoma trematodes.

Changes in the behavioral and immunological parameters of the mollusk Biomphalaria tenagophila induced by disruption of the circadian cycle as a consequence of continuous illumination.

In the present investigation we studied some behavioral and immunological parameters of adult gastropod mollusk, Biomphalaria tenagophila, which have been reproducing for several generations under laboratory conditions. One group of gastropods was kept on a 14-h light/10-h dark cycle, corresponding to a regular circadian cycle, and another group was exposed to continuous light for 48 h. Animals were studied along (behavioral groups) or immediately after (immunological groups) 48 h of regular circadian cycle or continuous light conditions. Stopping/floating, dragging and sliding were the behavioral aspects considered (N = 20 for regular cycle; N = 20 for continuous illumination) and number of hemocytes/microl hemolymph was the immunological parameter studied (N = 15 for regular cycle, N = 14 for continuous illumination). Animals under continuous illumination were more active (sliding = 33 episodes, dragging = 48 episodes) and displayed a lower number of hemocytes (78.0 +/- 24. 27/microl) when compared with mollusks kept on a regular circadian cycle (sliding = 18 episodes, dragging = 27 episodes; hemocytes = 157.6 +/- 53.27/microl). The data are discussed in terms of neural circuits and neuroimmunological relations with the possible stressful effect of continuous illumination.

Schistosoma mansoni: Continuous Variation in Susceptibility of the Vector Snail of Schistosomiasis, Biomphalaria tenagophila I. Self-Fertilization—Lineage

Mascara, D., Kawano, T., Magnanelli, A. C., Silva, R. P. S., Sant' Anna, O. A., and Morgante, J. S. 1999. Schistosoma mansoni: continuous variation in susceptibility of the vector snail of schistosomiasis, Biomphalaria tenagophila I. Self-Fertilization—Lineage. Experimental Parasitology93, 133–141. Artificial selection of Biomphalaria tenagophila snails for susceptibility to infection by Schistosoma mansoni (Brazilian SJ strain) was carried out from natural populations. After five self-fertilization generations, two lineages were isolated and were designated as SUSC (highly susceptible 93–100%) and RES (nonsusceptible 5–0%). Length of the prepatent period, cercarial production, and mortality of the hosts in postexposure were determined in all generations (F1–F8) and were analyzed as quantitative traits related to host susceptibility. Distribution patterns of frequencies were observed within snail families (samples derived from one F0 snail), these traits showing a significant influence by selection applied to susceptibility. The multiple quantitative classes were described in terms of continuous variation. During the selection of SUSC lineage, classes with higher values of prepatent length and lower cercarial production were eliminated, and the heritability calculated for these two traits was 0.811 and 0.709, respectively. Experimental results were correlated with an increase in the level of susceptibility in the generations selected and are discussed in relation to inheritance patterns as well as the quantitative variation of susceptibility.

Effect of self-fertilization on Biomphalaria tenagophila (Orbigny, 1835) (Pulmonata: Planorbidae)

Biomphalaria tenagophila is a simultaneous hermaphrodite freshwater snail, which can breed by self and cross-fertilization. It is, therefore, well suited for studying reproduction as an evolutive strategy. Several characteristics (shell size and age at sexual maturity, egg fecundity and fertility) were analyzed in four consecutive self-fertilized generations and compared to cross-fertilized individuals. The reproductive parameters were similar in the two groups. Shell size was significantly greater in the fourth self-fertilized generation than in the cross-fertilized individuals.

Crescimento de órgãos do aparelho reprodutor durante o desenvolvimento de Biomphalaria tenagophila (Orbigny) (Mollusca, Planorbidae)

Biomphalaria tenagophila é um hermafrodita simultâneo cujo investimento na função masculina foi avaliado pelo crescimento de seus órgãos sexuais em relação ao diâmetro da concha. Foram criadas novas técnicas para medir órgãos reprodutivos, sem aparentes distorções, e contar folículos do ovoteste. Durante o crescimento de espécimes sexualmente maduros de B. tenagophila, cresceu o número de folículos do ovoteste, mas seus números máximos e mínimos são menores do que os citados na literatura. O número de divertículos da próstata e de folículos do ovoteste de B. glabrata é maior do que o de B. tenagophila. Embora o comprimento do ovoteste, da próstata, da bainha do pênis e da glândula mucípara-ootecal variassem durante o crescimento do caramujo, não variou significativamente o número de divertículos da próstata.

The functional organization of the carrefour in the reproductive tract of Biomphalaria tenagophila (Mollusca, Planorbidae)

Summary A detailed morphological analysis of the carrefour, corresponding to the site of bifurcation of the hermaphroditic duct of the reproductive tract of Biomphalaria tenagophila (Mollusca, Planorbidae), has been carried out by light and electron microscopy, including 3D anatomical reconstruction. The carrefour receives the tangential entrance of the ovispermiduct and secretory duct of the albumen gland in its posterior face whereas the exits to the oviduct and spermiduct are situated in its anterior face. Histologically, this bulbuous organ is very similar to the ovispermiduct and thus may be considered as a hermaphroditic structure. It is lined by highly ciliated columnar epithelium with a few mucous secretory cells. The he structural analysis of the epithelium reveals the presence of long and abundant cilia and numerous microvilli in the apical surface of the ciliated cells, along with signs of micropinocytic activity. The observation of basal membrane infoldings with associated mitochondria indicates the existence of an apex-base motion of fluid through the carrefour epithelium. In contrast, the mucous cells show an intense secretory activity. Germ cell trafficking and sorting inside the carrefour are very complex, involving the segregation of oocytes and spermatozoa produced in the ovotestis of the animal itself and the exogenous spermatozoa acquired by copulation. Based on morphological evidence presented in this work, we concluded that the flux produced by ciliary beating of the epithelial cells along with the insertion angle and relative positioning of the openings of the ducts in the carrefour are the most important factors in the traffic and differential destiny of the germ cells inside the organ. The presence of secretion of the albumen gland in the so-called fertilization pocket should prevent the sperm entrance into the oocyte and thus the zygote formation in this specialized region of the carrefour.

The influence of self-fertilization performance and copulation behaviour in reproduction by cross-fertilization in groups of Biomphalaria tenagophila (Mollusca, Planorbidae).

The following hypotheses were tested for groups of simultaneous hermaphrodites Biomphalaria tenagophila: (a) snails that have low reproductive success during the process of self-fertilization do not increase their reproductive success after the end of grouping; (b) the copulation behaviour and the presence of one snail whose eggs have a low viability rate influence the partner's reproductive success by cross-fertilization. Groups were constituted by a homozygous pigmented snail and two albinos: one with a viability rate higher than 70% ("good reproducers") and the other less than 10% ("bad reproducers"). All pigmented snails had viability rates higher than 70%. The "good" and "bad" reproducer albino snails had similar copulation behaviour. However, after the end of grouping, the "bad reproducers" continued to have viability rates less than 10% over 30 days. In 100% of the cases that pigmented snails copulated (performing either a male role or simultaneously male and female roles) exclusively with "good" reproducer albinos, they presented high reproductive success (producing, on average of 8.4 pigmented embryos/egg-mass). However, in 100% of the cases that pigmented snails copulated with both partners, the "good" reproducer albino snails produced none or very few embryos (the highest average was 2.2 pigmented embryos/egg-mass). Therefore, the production of viable embryos by cross-fertilization was more influenced by self-fertilization performance than by copulation behaviour. The presence of a snail whose eggs have a low viability rate could decrease their partners reproductive success.