Ação moluscicida de Moringa oleifera Lam sobre o molusco biomphalaria glabrata (Say, 1818) hospedeiro intermediário do Schistosoma mansoni (Sambon, 1907) e efeitos ecotoxicológicos em organismos aquáticos não alvo / Molluscicidal activity of moringa oleifera lam on the snail biomphalaria glabrata (Say,1818) intermediate host of schistosoma mansoni (Sambon, 1907) and ecotoxicological effects on non target aquatic organisms

A esquistossomose é uma doença parasitária de veiculação hídrica causada pelo trematódeo Schistosoma mansoni, [...]. A doença é de profilaxia complexa, já que os moluscos aquáticos são de difícil controle, e pela parasitose incidir em zonas que favorecem um maior contato do homem com a água. No Brasil ocorrem dez espécies e uma sub-espécie do gênero Biomphalaria, sendo três espécies hospedeiras naturais do S. mansoni: Biomphalaria glabrata, Biomphalaria straminea e Biomphalaria tenagophila. O controle químico é utilizado para reduzir as populações destes hospedeiros intermediários sendo a Niclosamida o moluscicida recomendado pela OMS, porém com alta toxicidade para muitos organismos aquáticos. Moluscicidas derivados de plantas têm provado sua efetividade, porém exigem cuidados no manuseio, pois muitas espécies são tóxicas a humanos e organismos não alvo. Iniciativas no passado para o uso de plantas como moluscicida foram pouco promissoras ou desencorajadas em programas em larga escala devido ao pequeno valor agregado que possuem para as comunidades ou gestores públicos. A planta Moringa oleifera não é tóxica sendo utilizada na alimentação humana e animal, com vários estudos realizados para testar seu múltiplo uso, principalmente quanto à sua vi propriedade purificadora de águas. No presente estudo a semente moída de M. oleifera (ESSMol) foi avaliada pela primeira vez quanto à sua atividade moluscicida contra os moluscos B. glabrata, Physa marmorata e Melanoides tuberculatus...

Schistosomiasis is a waterborne parasitic disease caused by thetrematode Schistosoma mansoni [...]. The disease prophylaxis is complex, since their hosts, aquatic snails are difficult to control, and since this parasitosis occurs in very hot and irrigated areas favoring an increased human contact with the water. In Brazil there are 10 species and one subspecies of the genus Biomphalaria, three of which are natural hosts of S. mansoni: Biomphalaria glabrata, Biomphalaria straminea and Biomphalaria tenagophila. Chemical control is used to reduce populations of vector snails being Niclosamide the only recommended by the HO,demonstrating, however, severe toxicity to some aquatic organisms. Plantderived molluscicides have proven their effectiveness requiring, however, carein handling because some species possess toxic properties to humans andnon-target organisms. Past initiatives to make effective the practice of use ofplants with molluscicidal property have been unpromising or not carried forwardin large scale programs due to the small value such plants have to targetcommunities or public managers. The plant Moringa oleifera is non toxic tohumans and used as food for humans and other animals with several studieshaving been done to test the multiple uses of this plant, particularly with respect viii to its water purifying property. In this study the ground seed of M. oleifera (GSEMol) was first evaluated for its molluscicidal activity against the snails B.glabrata, Physa marmorata and Melanoides tuberculatus...

Habitat preference of freshwater snails in relation to environmental factors and the presence of the competitor snail Melanoides tuberculatus (Müller, 1774)

Our objective is to evaluate the habitat preference of freshwater snails in relation to environmental factors and the presence of the competitor snail Melanoides tuberculatus. In the first phase, snails was collected at 12 sites. This sampling sites presented a degree of organic input. In the second phase 33 sampling sites were chosen, covering a variety of lotic and lentic environments. The snail species found at Guapimirim, state of Rio de Janeiro, displayed a marked habitat preference, specially in relation to the physical characteristics of each environment. Other limiting factors for snail distribution at the studied lotic environments were the water current velocity and the amount of organic matter, mainly to Physa marmorata, M. tuberculatus, and Biomphalaria tenagophila. The absence of interactions between M. tuberculatus and another snails could be associated to the distinct spatial distribution of those species and the instability of habitats. This later factor may favor the coexistence of M. tuberculatus with B. glabrata by reduction of population density. In areas of schistosomiasis transmission some habitat modification may add to the instability of the environment, which would make room for the coexistence of M. tuberculatus and Biomphalaria spp. In this way, some of the usual measures for the control of snail hosts would prevent the extinction of populations of Biomphalaria spp. by M. tuberculatus in particular habitats.

Apparent competition through facilitation between Melanoides tuberculata and Biomphalaria glabrata and the control of schistosomiasis

Interactions between two species that result in reduced growth rates for both and extinction of one of the species are generally considered cases of asymmetric interspecific competition. Exploitative or interference competition is the usual mechanism invoked. Here we describe another mechanism producing the same result, named apparent competition through facilitation (ACF), observed between Melanoides tuberculata and Biomphalaria glabrata populations. The superior competitor actually gives some benefit to the other species, whose population becomes unstable with progressively increasing oscillations, leading to extinction. A model of ACF using difference equations suggests initial dynamics distinct from traditional interspecific competition. The dynamics of two freshwater snails in the field and in laboratory experiments suggest ACF, and these relations should be considered in studies of schistosomiasis control. ACF could occur in natural populations, but might have gone undetected because the final result is similar to traditional interspecific competition

Relato preliminar de reflexões sobre prevenção de impasses no enfrentamento de doenças transmissíveis de origem socioambiental / Preliminary report of reflections on prevention of impasses facing diseases of social-environmental causes

O enfrentamento de doenças transmissíveis de origem socioambiental esbarra frequentemente em dificuldades de etendimento entre comunidades, poder público e cientistas, ainda que haja recursos técnicos abundantes e adequados. Esse trabalho descreve uma experiência de reflexaão sobre dificuldades encontradas pelos integrantes de um grupo interdisciplinar e multissetorial para esse enfrentamento e sugre uma metodologia baseasda em diálogo para prevenção de impasses entre setores, disciplinas e sujeitos. A metoldologia consiste em um processo, ainda em curso, baseado na consolidação de um grupo multissetorial e interdisciplinar, afeito ao diálogo. A reflexão sobre o tema gerou um anteprojeto sobre o comportamento humano ante à transmissão de doenças de veiculação hídrica em municípios do Rio de Janeiro. Outro produto foi um texto em que são sugeridos caminhos para o diálogo

Facing diseases of social-environmental causes is frequently troubled by misunderstanding among communities, public power, and scientists, inspite of the availability of abundant and appropriate technical resources. This work is based on the experience of reflections about difficulties encountered by an interdisciplinary and multisectoral group and proposes dialogue as a method to prevent impasses between sectors, disciplines and subjects. The methodology consists of a process, still in progress, based on the consolidation of a multisectoral and interdisciplinary group accustomed to dialogue. Discussions of this theme generated the proposal of a project about human behavior regarding water-borne diseases in municipal districts of Rio de Janeiro. Another product was a text suggesting methods for achieving dialogue.

The molluscicidal activity of niclosamide (Bayluscide WP70®) on Melanoides tuberculata (Thiaridae), a snail associated with habitats of Biomphalaria glabrata (Planorbidae)

The aim of this study was to determine the toxicity of niclosamide (Bayluscide ®) on Melanoides tuberculata and Biomphalaria glabrata under laboratory conditions. The latter species is the intermediate host of Schistosoma mansoni (Sambon 1917). M. tuberculata was successfully used as competitor of B. glabrata in biological control programs in French West Indies. Both molluscicide and biological control using M. tuberculata have proved to be successful in reducing the population density of B. glabrata. The associated use of molluscicide in this area would be an effective measure if M. tuberculata were less susceptibility to the molluscicide than B. glabrata. Three hundreds individuals each of B. glabrata and of M. tuberculata, collected in Sumidouro, State of Rio de Janeiro, were used in the experiment. The molluscs were exposed to 14 different concentrations of niclosamide as recommended by the World Health Organization. Probit analysis was used to determine the LC 50 and LC 90. The LC 50 and LC 90 values for B. glabrata were 0.077 mg/l and 0.175 mg/l, respectively and the LC 50 and LC 90 values for M. tuberculata were 0.082 mg/l and 0.221 mg/l respectively. As the lethal concentrations of niclosamide were approximately the same to both species, this could be a disadvantage when controlling B. glabrata with niclosamide in an area of M. tuberculata occurrence. It migth therefore be preferable to utilize the latex extracted from the Euphorbia splendens, which presented a much higher efficiency for B. glabrata than to M. tuberculata

Interaction between the Intermediate Host of Schistosomiasis in Brazil Biomphalaria glabrata (Planorbidae) and a Possible Competitor Melanoides tuberculata (Thiaridae): I. Laboratory Experiments

The biological control of Biomphalaria glabrata, intermediate host of Schistosoma mansoni, is one the accepted options to fight schistosomiasis. One of the most promising candidates to control B. glabrata is the snail Melanoides tuberculata, a potential competitor. However, the mechanisms of interaction between the two species are not clear. Our objective is to determine if M. tuberculata indeed compete with B. glabrata, using two laboratory experiments. In Experiment 1, we tested the effect of the presence of M. tuberculata on the fecundity and mortality rates of B. glabrata. In Experiment 2, we tested if there was a direct or indirect interaction between the two species. In Experiment 1, M. tuberculata was eliminated after the peak in reproductive activity of B. glabrata. In Experiment 2, B. glabrata produced more egg masses when raised with M. tuberculata. The conditions leading to this unexpected positive effect of M. tuberculata on the fecundity of B. glabrata need further clarification, but emphasize that detailed studies of the interaction between these species in the conditions of the local environment should be considered

The molluscicidal activity of the latex of Euphorbia splendens var. hislopii on Melanoides tuberculata (Thiaridae), a snail associated with habitats of Biomphalaria glabrata (Planorbidae)

The use of the latex of Euphorbia splendens var. hislopii was considered as an effective control method for Biomphalaria glabrata in Sumidouro, Rio de Janeiro. However, the appearance and expansion of the snail Melanoides tuberculata since August 1997, with the concomitant reduction of the population of B. glabrata suggest that competitive exclusion might be taking place. Depending on the susceptibility of the thiarid to the E. splendens toxin, the natural control that is occurring could be interrupted by the employment of the latex if the planorbid were less susceptible to the toxin. The aim of this study is to investigate the molluscicidal activity of the latex on M. tuberculata. We used 420 M. tuberculata, from Sumidouro. Fourteen different latex concentrations were tested using World Health Organization general methodology. Probit analysis was used for LD90 and LD50 determination. The LD50 was 3.57 mg/l and LD90 was 6.22 mg/l. At the highest concentration (10 mg/l) there was no survival. No significant differences among replicas (chi2 = 8.31; gl = 13; p > 0.05) were found. The LD90 dose for M. tuberculata was 13.8 times greater than that for B. glabrata, so that the molluscicide in the presence of the thiarid may have a synergic effect on reduction of Biomphalaria populations

Soluçäo de problemas em saúde e ambiente; ciência pós-normal e comunidade ampliada de pares em um município brasileiro de pequeno porte / Problems solving in health and environment: \"post-normal science\" and \"extended peer community\" in a small brazilian municipality

Apresenta o caminho pelo qual temos evoluído em direçäo a uma soluçäo para os problemas de Guapimirim (Rio de Janeiro, Brasil) na área de saúde e ambiente. Objetiva atingir a partir de um estudo interdisciplinar e de uma parceria que vem assimilando, gradativamente, conceitos e práticas propostos por teóricos contemporâneos para lidar com complexidade, incerteza e avaliaçäo. Os conceitos de ciência "pós-normal", "comunidade ampliada de pares" e "transdisciplinaridade" servem de base para o entendimento do empreendimento científico em curso naquele município, e para a formulaçäo de uma proposta para sua continuidade.