The control of the schistosome-transmitting snail Biomphalaria glabrata by the plant Molluscicide Euphorbia splendens var. hislopii (syn milli Des. Moul): a longitudinal field study in an endemic area in Brazil.

Under laboratory conditions, latex from Euphorbia splendens has shown promise as a plant molluscicide for control of Biomphalaria species, intermediate hosts for Schistosoma mansoni. The purpose of this study was to evaluate its efficiency under field conditions. Application of filtered latex at 12 ppm to one stream in an endemic rural area in Minas Gerais state, Brazil, in September 1995, did result in a reduction in snail density as compared to an untreated stream but the snail population recovered quickly. However, two applications with a two-week interval of unfiltered E. splendens latex at 5 ppm in November 1996 in the same stream resulted in complete disappearance of B. glabrata and snails did not reappear until the 14th month after the applications. In the control stream, without treatment, the snails were found during all months. Laboratory studies confirmed that unfiltered latex is a more potent molluscicide than filtered latex. Considering the advantages of the latex such as its low toxicity to other aquatic animals and its photobiodegradability, as well as the simple method of application, this natural product is promising as an effective molluscicide.

Screening of Asteraceae (Compositae) plant extracts for larvicidal activity against Aedes fluviatilis (Diptera:Culicidae).

Ethanol extracts of 83 plants species belonging to the Asteraceae (Compositae) family, collected in the State of Minas Gerais, Brazil, were tested for larvicidal activity against the mosquito Aedes fluviatilis--Diptera: Culicidae). The extract from Tagetes minuta was the most active with a LC90 of 1.5 mg/l and LC50 of 1.0 mg/l. This plant has been the object of several studies by other groups and its active components have already been identified as thiophene derivatives, a class of compounds present in many Asteraceae species. The extract of Eclipta paniculata was also significantly active, with a LC90 of 17.2 mg/l and LC50 of 3.3 mg/l and no previous studies on its larvicidal activity or chemical composition could be found in the literature. Extracts of Achryrocline satureoides, Gnaphalium spicatum, Senecio brasiliensis, Trixis vauthieri, Tagetes patula and Vernonia ammophila were less active, killing more than 50% of the larvae only at the higher dose tested (100 mg/l).

Evaluation of the molluscicidal properties of Euphorbia splendens var. hislopii (N.E.B.) latex: experimental test in an endemic area in the State of Minas Gerais, Brazil.

Following the positive results obtained regarding the molluscicidal properties of the latex of Euphorbia splendens that were corroborated in laboratory and field tests under restricted conditions, a field study was conducted in experimental streams located in an endemic area. After recording the average annual fluctuations of vectors in three streams, a solution of E. splendens latex at 12 ppm was applied in stream A, a solution of niclosamide at 3 ppm that was applied in stream B and a third stream (C) remained untreated for negative control. Applications of E. splendens and niclosamide resulted in a mortality of 100% among the snails collected in the streams A and B. No dead snails were found in the negative control stream. A monthly follow-up survey conducted during three consecutive months confirmed the return of vectors to both experimental streams treated with latex and niclosamide. This fact has called for a need to repeat application in order to reach the snails that remained buried in the mud substrate or escaped to the water edge, as well as, newly hatched snails that did not respond to the concentration of these molluscicides. Adults snails collected a month following treatment led us to believe that they had migrate from untreated areas of the streams to those previously treated.

[Preliminary trials of Guaiacum officinale L. as a molluscicide]. / Ensaios preliminares do Guaiacum officinale L. como moluscicida.

Aqueous suspensions of fruit's pericarp, leaves, root's bark and seeds of Guaiacum officinale were tested at different concentrations as molluscicide, cercaricide and piscicide. In the laboratory the suspension of fruit's pericarp produced 100% mortality for egg masses of B. glabrata at 100 ppm, for adult snails of Biomphalaria glabrata, B. straminea and B. tenagophila at 20 ppm, for Lebistes reticulatus (fishes) at 5 ppm and Schistosoma mansoni's cercariae at 1 ppm. The ethanolic extract of fruit's pericarp was not active against adult snails of B. glabrata. The lethal dose for adult snails(DL90) of the aqueous suspension of fruit's pericarp after 24 hours exposure, were: 15 ppm for B. glabrata; 14 ppm for B. straminea and 18 ppm for B. tenagophila. The DL90 of aqueous suspensions of root's bark, seeds and leaves were 57 ppm, 33 ppm and 15 ppm, respectively. In the field, B. glabrata adult snail mortality was 68% at 20 ppm and 100% at 40 ppm, when using suspension of fruit's pericarp.

[Chemoprophylactic activity on Schistosomiasis mansoni of soaps containing essential oil from the fruits of Pterodon pubescens]. / Atividade quimioprofilática na esquistossomose mansoni de sabonetes contendo óleo essencial de frutos de Pterodon pubescens.

The chemoprophylactic action of the essential oil of the fruit of Pterodon pubescens Benth (Leguminosae), incorporated in different soap formulations, was studied in experimental schistosomiasis. The formulations were used locally on the tails of mice which were exposed to Schistosoma mansoni cercariae immediately, 24, 72 or 168 hours later by the method of tail immersion. Protection was evaluated 45 days after exposure when the mice were sacrificed and the worms collected by perfusion. The results showed levels of protection varying from 0.0 to 100% depending on the formulation used. A methodology that allowed the evaluation of soap protection of mice exposed to natural infection in snail infested streams on the outskirts of Belo Horizonte, MG, was also developed. Promising results were obtained in that protection of between 57.5 and 31.1% was observed in field trials when soap was applied to the animals 24 and 48 hours earlier. Preliminary studies evaluating irritation and toxicity were favorable and showed that this new prophylactic weapon could contribute to the control of schistosomiasis.

The prolonged use of niclosamide as a molluscicide for the control of Schistosoma mansoni.

Applications of niclosamide at three-monthly intervals were undertaken for 14 years in foci of Biomphalaria glabrata in the water sources of Peri-Peri (Capim Branco, MG). All the residents of the area were submitted to an annual fecal examination (Kato/Katz) and those individuals eliminating Schistosoma mansoni eggs were treated with oxamniquine. A malacological survey was undertaken at three-monthly intervals by means of ten scoops with a perforated ladle each ten metres along the two banks of the ditches and streams of the region. Where snails were found, molluscicide was applied by means of dripping or aspersion using a 3 ppm aqueous suspension of niclosamide. Initially, a mean of 14.3% of snails in the region were found to be eliminating cercariae. Following the first four applications of molluscicide, this was reduced to 0.0% and maintained at about 1.5% throughout the program. Thus, there was a continued possibility of schistosomiasis transmission in the area and it was observed that the population of snails reestablished itself within three months of molluscicide application. The results obtained in this study do not encourage the continual use of niclosamide as the only method of control of schistosomiasis.

[The use of the shell of the cashew nut, Anacardium occidentale, as an alternative molluscacide]. / O uso da casca da castanha do caju, Anacardium occidentale, como moluscicida alternativo.

Bioassays using hexanolic extracts of cashew nut shells, of Anacardium occidentale, collected in Ceará in 1972 (Sample 1) and 1987 (Sample 2) were undertaken with adult snails and egg masses of Biomphalaria glabrata, B. tenagophila and B. straminea both in the laboratory and in the field. Non extracted shells, 18.5 g, sample 1, were also tested with adult snails and egg masses of the three species. The toxicity of extract was tested with fish (Poecilia reticulata) and tadpoles. The lethal concentration, CL90, of sample 1 was from 2.0 to 2.2 ppm for adult snails of the three species. With sample 2, the CL90 was 2.0, 0.5 and 30.0 ppm for B. glabrata adults, newly hatched snails and egg mass respectively. Non extracted shells caused 40-80% mortality of adult snails, 22-35% mortality of embryos and 40-55% reduction of egg production. The hexanolic extract, sample 2, were innocuous for tadpole and fish at 2 ppm. In the field, in pools of still water treatment with 20 ppm of extract, sample 1, caused a 97.1% mortality of B. straminea and 100% mortality of B. glabrata and B. tenagophila. Using Niclosamide, at 3 ppm, 100% mortality of the three species occurred.

Evaluation of the molluscicidal properties of Euphorbia splendens var. hislopii (N. E. B.) (Euphorbiaceae)--1. Experimental test in a lentic habitat.

The latex of Euphorbia splendens var. hislopii, at concentrations between 5 to 12 mg/l, kills 100% of the population of Biomphalaria glabrata in a lentic habitat, after 24 h. The lyophilized latex, stocked for 18 months, killed only 34.2% of the snails, at the concentration of 5 mg/l, and 96.0% at 12 mg/l. No lethal effect was observed among Pomacea haustrum exposed to the same concentrations of the molluscicide.

Repovoamento de criadouros de Biomphalaria glabrata apos tratamento com niclosamida / Repopulation of breeding habitats of Biomphalaria glabrata after treatment with niclosamide

Experimentos foram feitos no laboratorio e no campo nos anos de 1980 a 1984, objetivando detectar as causas do repovoamento de criadouros de Biomphalaria glabrata apos tratamento com niclosamida. Os bioensaios no laboratorio mostraram que a suscetibilidade a niclosamida emulsionavel de B. glabrata coletada mensalmente em um sistema de valas de irrigacao, variou durante o ano. As concentracoes letais 'CL IND. 90' foram 0,15 'mgl POT. -1' a 0,60 'mgl POT. -1', apresentando diferencas significantes estatisticamente (p<0,01) nos meses de maio/82 e janeiro/83 e dezembro/82 e janeiro/83, relacionadas a nutricao. No campo, foram tratados dois tipos de focos com solucao aquosa a 10 ppm de niclosamida. O primeiro era formado por reservatorio com cerca de 12.000 litros de agua e continha 14,5 por cento de moluscos infectados pelo Schistosoma mansoni. Uma unica aplicacao do produto, seguida de esvaziamento e limpeza do reservatorio, eliminou os moluscos. O segundo, era constituido por sistema de valas e poco com 5,6 por cento de moluscos infectados pos S. mansoni. Uma unica aplicacao do produto, sem limpeza das valas, reduziu a densidade planorbidica 98 por cento. As causas da sobrevivencia de 2 por cento dos moluscos do sistema de valas, sao discutidas, sendo relacionadas ao substrato do criadouro e a tecnica utilizada no tratamento.

[Repopulation of breeding habitats of Biomphalaria glabrata after treatment with niclosamide]. / Repovoamento de criadouros de biomphalaria glabrata após tratamento com niclosamida.

Experiments were undertaken both in the laboratory and in the field between 1980-1984 to evaluate the causes of repopulation of breeding places of Biomphalaria glabrata following treatment with Niclosamide. Laboratory bioassays showed that the susceptibility to emulsifiable Niclosamide of B. glabrata collected monthly from an irrigation ditch system varied during the year. Lethal concentrations (LC90) ranged between 0.15 mg/l-1 and 0.60 mg/l-1. Statistically significant differences (alpha = 0.01) were evident between the months of May/82 and January/83 and December/82 and January/83, and were related to snail nutrition. In the field two types of foci of B. glabrata were treated with 10 ppm of Niclosamide. The first one consisted of a reservoir of 12000 1 of water in which 14.5% of snails were infected with Schistosoma mansoni. One application of molluscicide followed by cleaning of the reservoir eliminated all the snails. The second one consisted of an irrigation system in which 5.6% of the snails were infected with S. mansoni. One application of molluscicide without cleaning the ditches reduced the density of snails by 98%. The causes of the survival of 2.0% of the snails in the ditches are discussed in relation to the substratum of the breeding places and the treatment technique.

[Molluscacide and cercariacide activity of different species of Eucalyptus]. / Atividade moluscicida e cercaricida de diferentes espécies de Eucalyptus.

Hydrolates and essential oils of several Eucalyptus species were tested on adult snails and egg masses of Biomphalaria glabrata, and cercaria of Schistosoma mansoni. These products were obtained by vapor dragging. Eight out of 21 hydrolates presented activity on snails, nine on egg masses and three on cercaria at 1:4 dilutions. Eleven oils were active on both snails and egg masses at 20 ppm concentrations. The hydrolate of E. deanei was active both on snails, egg masses and cercaria at 1:4 dilution and its essential oil at 20 ppm.

[Molluscacide activity of a mixture of 6-n-alkyl salicylic acids (anacardic acid) and 2 of its complexes with copper (II) and lead (II)]. / Atividade moluscicida da mistura de ácidos 6-n-alquil salicílicos (ácido anacárdico) e dos seus complexos com cobre (II) e chumbo (II).

The molluscicide activity of hexanic extract from Anacardium occidentale L. (cashew) nut shell, of copper (II) complex, of lead (II) complex and anacardic acid has been compared in the laboratory in an attempt to obtain better stability than anacardic acid. This was obtained from the hexanic extract of the cashew nut shell by precipitation with lead (II) hydroxide or cupric sulfate plus sodium hydroxide or (II) cupric hydroxide followed by treatment of lead (II) complex with a diluted solution of sulfuric acid. Ten products of the mixture obtained were tested on adults snails of Biomphalaria glabrata at 1 to 10 ppm. The most active products were copper (II) complex, obtained by cupric sulfate plus sodium hydroxide, and anacardic acid (sodium hydroxide) which presented activity at 4 ppm. The anacardic acid's lead content was above the limits accepted by the United States standards.

[Effect of several extracts derived from plants on the survival of larvae of Aedes fluviatilis (Lutz) (Diptera: Culicidae) in the laboratory]. / Influência de diversos derivados de vegetais na sobrevida das larvas de Aedes fluviatilis (Lutz) (Diptera: Culicidae) em laboratório.

The larvicidal properties of 34 plant extracts were tested against Aedes fluviatilis (Lutz) (Diptera: Culicidae) larvae, at 100, 10 and 1 ppm concentrations; 26.6% of the extracts enhanced larval mortality (alpha = 0.05) at 100 ppm (Anacardium occidentale, Agave americana, Allium sativum, Coriandrum sativum, Nerium oleander, Spatodea campanulata, Tibouchina scrobiculata and Vernonia salzmanni). Anacardic acid (A. occidentale) was effective at 10 ppm and A. sativum (crude extract) at 1 ppm.

[Molluscicide activity of a butanol extract from Phytolacca dodecandra (endod) on Biomphalaria glabrata]. / Atividade moluscicida do extrato butílico de phytolacca dodecandra (Endod) sobre Biomphalaria glabrata.

A buthanol extract of Phytolacca dodecandra (type 44) obtained from Ethiopia berries, was tested as molluscicide in our laboratory and in the field. The lethal dose (LD90) for adult snails, newly hatched and egg-masses of Biomphalaria glabrata, in 24 hours exposure, were of 4.5, 23.0 and 102.0 ppm respectively. The LD90 for the fish Lebistes reticulatus was of 2.0 ppm. These results are similar to those of Lemma (1984) in Ethiopia. In two water ponds treated with 10 ppm of the buthanol extract or 3 ppm of niclosamide the mortality rates of B. glabrata were of 84.6 and 100.0%, respectively. Both treatments were toxic for L. reticulatus in the field trials. The possibility of using molluscicides derived from plants is discussed as an alternative for treatment of schistosomiasis foci in Brazil.

[Molluscicide activity of some natural products on Biomphalaria glabrata]. / Atividade moluscicida de alguns produtos naturais sobre Biomphalaria glabrata.

The molluscicide activity of aqueous (macerated and boiled), hexanic and ethylic extracts of Aristolochia brasiliensis, Caesalpinia peltophoroides, Caesalpinia pulcherrima, Delonix regia, Spathodea campanulata and Tibouchina scrobiculata was evaluated in the laboratory. The solutions obtained from those extracts were tested on adults and egg masses of Biomphalaria glabrata reared in the laboratory at 1, 10, 20, 100 and 1000 ppm concentrations. The most active of the extracts studied was D. regia flowers' (flamboyant) ethylic extracts which presented molluscicidal activity on adult snails at 20 ppm.

Ensaios preliminares em laboratorio para verificar a acao moluscicida de algumas especies da flora brasileira. / Preliminary assay in laboratory to verify the molluscacide effect of some species of the Brazilian flora

Estudou-se em laboratorio a atividade moluscicida de 68 extratos de 23 plantas brasileiras. As solucoes em agua desclorada dos extratos hexanicos e etanolico, nas concentracoes de 1,10 e 100 ppm, foram testadas sobre caramujos adultos e desovas de Biomphalaria glabrata, criados em laboratorio. As plantas que demostraram acao moluscicida na concentracao de 100 ppm foram: Arthemisia verlotorum Lamotte, Caesalpinia peltophoroides Benth, Cassia rugosa G.Don., Eclipta alba Hassk, Euphorbia pulcherrima Willd, Euphorbia splendens Bojer, Joannesia princeps Vell, Leonorus sibiricus L., Macrosiphonia guaranitica Mell Nerium oleander L., Palicourea nicotianaefolia Cham. e Schlech., Panicum maximum M.Rumex crispus L., Ruta graveolens L., e Stryphnodendron barbatiman M