The molluscicidal activities of some Euphorbia milii hybrids against the snail Indoplanorbis exustus.

The objective of this study was to observe the molluscicidal activities of Euphorbia milli, known as "poysean" in Thailand, against Indoplanorbis exustus. Latex from 12 different E. milii hybrids was screened for its molluscicidal activities. Indoplanorbis exustus were exposed for 24 and 48 hours to the latex at various concentrations ranging from 6 to 25 ppm and mortality rates were recorded. Eight hybrids of latex were effective. The six most effective hybrids were E. milii Dang-udom, E. milii Arunroong, E. milii Raweechotchuong, E. milii Srisompote, E. milii Sri-umporn and E. milii Tongnopakun, which killed all snails after 24 hours of exposure. Under the same conditions, latex of E. milii Dowpraket and E. milii Promsatid killed 50% of the snails. Such results indicate that these 6 hybrids seem promising as natural molluscicidal agents.

Effect of the pesticides carbofuran [Carbamate] and Profenophos [Organophosphorus] on Biomphalaria alexandrina and on its infection with Schistosoma mansoni miracidia

Carbofuran [carbamate pesticide] and Profenophos [organophosphorus pesticide] showed molluscicidal effect on Biomphalaria alexandrina snails, with the LC[50] 1.42 ppm and 1.29 ppm, respectively Maintaining Biomphalaria alexandrina at sublethal concentrations of these compounds [0.5, 0.75, and 1.0 ppm] reduced the snail survival rate and net reproductive rate [R[0]] [E L[x]M[x]] compared with the control snail group. The percentage reduction in R[0] was 86.9, 90.8, and 93.9 for the tested concentrations of Carbofuran and 86.8, 82.9 and 88.5 for the tested concentrations of Profenophos, respectively. The susceptibility of Biomphalaria snails to infection with Schistosoma mansoni miracidia and further infectivity of this parasite were also reduced. Increasing the pesticide concentration increased the magnitude of reduction reaching 80.7% and 89.3% for the two pesticides, respectively. Pesticide may be considered one of the factors contributing in the disappearance of snail vectors on reaching water bodies as residues from pesticidal activities and consequently hindering schistosomiasis transmission

Actividad molusquicida del Paraiso (Melia azedarach L.) (Meliaceae) sobre Lymnaea cubensis, molusco vector de Fasciolosis / Molluscicidal activity of Paraiso (Melia azedarach L.) (Meliaceae) on Lymnaea cubensis, host snail of Fasciolosis

A Fasciolosis constitui em diversas regiöes fonte importante de perdas econômicas, e quando näo se adotam medidas de controle de seus hospedeiros (moluscos), junto a condiçöes ecológicas favoráveis, pode ocorrer o aparecimento de casos isolados de Fasciolosis humana. Dentro dos métodos alternativos para o seu controle está o uso de extratos vegetais e se tem pretendido avaliar o provável emprego do suco extraíso do fruto e sementes do Paraiso (Melia azedarach L.), no controle de Lymnaea cubensis, principal vetor da Fasciolosis em Cuba. Diferentes concentraçöes do suco extraído do fruto e semente do Paraiso (Melia azedarach L.) foram testadas para determinar as doses médias letais (DL50) e máxima (DL90) usando um programa computadorizado PROBIT-LOG. Sete séries experimentais foram realizadas, usando 72 moluscos em cada uma. Para determinar a influência sobre a freqüência cardíaca foram testados três grupos de 10 moluscos, dois foram tratados com as CL50=0,88627 e CL90=1,7641, respectivamente, enquanto que o terceiro foi considerado como controle. Observou-se uma marcada influência de ambas as doses sobre a freqüência cardíaca do molusco estudado. Os resultados foram alentadores, pois demonstraram um potencial uso dessa planta no controle de moluscos näo desejados

Estudo ecotoxicológico do látex moluscicida da coroa-de-cristo (euphorbia milii var histopii) / Study on the ecotoxicity ot the molluscicida latex of \"crow-of-thorns\" (Euphorbua milli var histopii)

Investiga a toxicidade do látex à organismos näo-alvo do ecossistema aquático. A toxicidade aguda do látex liofilizado para caramujos do gênero Biomphalaria e para organismos näo-alvo foi avaliada através do sistema de exposiçäo estático. Os resultados (CL50 ou CE com o intervalo de confiança 95 por cento) foram os seguintes: letalidade para peixes: "paulistinha" (brachydanio rerio) - 24 horas = 1,15 (1,00-1,31) mg/l; 48 horas = 0,96 (0,84-1,070 mg/l e "guppy" (poecilia reticulata) - 24 horas = 1,71 (1,51-1,87) mg/l; 48 horas = 1,39 (1,18-1,55) mg/l. Imobilizaçäo para microcustáceos: daphnia similis - 24 horas = 1,04 (0,86-1,24) mg/l 48 horas = 0,37 (0,28-0,47) mg/l e ceriodaphnia dubia - 24 horas = 1,45 (1,06-2,03) mg/l; 48 horas = 1,06 (0,89-1,41) mg/l. Letalidade para o microcustáceo de águas salinas artemia sp.-24 horas = 24,23 (15,90-44,23) mg/l; 48 horas = 0,94 (0,67-1,25) mg/l. Letalidade para o oligoqueta tubifex tubifex siolii - 24 horas = 0,65 (0,58-0,71) mg/l; 48 horas = 0,31 (0,21-0,44) mg/l. Letalidade para insetos (larvas de primeiro e terceiro estágios de aedes aegypti, aedes fluviatilis e anopheles albitarsis); > 100 mg/l. Leatalidade para caramujos-alvo: biomphalaria tenagophila - 24 horas = 0,13 (0,09-0,19) mg/l; 48 horas = 0,08 (0,06-0,12) mg/l e biomphalaria glabrata - 24 horas = 0,26 (0,19-0,34) mg/l; 48 horas = 0,13 (0,10-0,17) mg/l. Letalidade para caramujos näo-alvo: helisoma duryi - 24 horas = 0,20 (0,13-0,35) mg/l; 48 horas = 0,10 (0,05-013) mg/l e pomacea sp.-24 horas = 12,46 (9,89-15,14) mg/l; 48 horas = 10,51 (8,39-12,66) mg/l. O látex näo inibiu o crscimento das algas clorofíceas slenastrum capricornutum e chlorella vulgaris. O látex também näo demonstrou efeito inibitório (em concentraçoes até 100 mg/l) para as bactérias escherichia coli, pseudomonas aeruginose a pseudomonas putida. Paralelamente foram realizados testes com a niclosamida para fins comparativos. Foi avaliada a estabilidade da atividade moluscicida da soluçäo aquosa de látex exposta a luz visível. Soluçoes de látex (10mg/l) em água destilada foram expostas luz visível (5000 lux) por 24, 48 e 96 horas. Soluçoes de látex fresco (10mg/l) e de látex protegido da luz (10mg/l) foram utilizadas como controles. Foram preparadas diluiçoes de 0,5 e 1,0 mg/l para testar a atividades moluscicida das soluçoes contra biomphalaria glabrata....

Evaluation of temporal, seasonal and geographic stability of the molluscicidal property of Euphorbia splendens latex

Laboratory tests with aqueous solutions of Euphorbia splendens var. hislopii latex have demonstrated seasonal stability of the molluscacidal principle, with LD90 values of 1.14 ppm (spring), 1.02 ppm (fall), 1.09 ppm (winter), and 1.07 ppm (summer) that have been determined against Biomphalaria tenagophila in the field. Assays on latex collected in Belo Horizonte and Recife yielded LD90 values similar to those obtained with the reference substance collected in Rio de Janeiro (Ilha do Governador), demonstrating geographic stability of the molluscacidal effect. The molluscacidal action of aqueous dilutions of the latex in natura, centrifuged (precipitate) and lyophilized, was stable for up to 124 days at room temperature (in natura) and for up to 736 days in a common refrigerator at 10 to 12 degrees C (lyophilized product). A 5.0 ppm solution is 100% lethal for snails up to 13 days after preparation, the effect being gradually lost to almost total inactivity by the 30th day. This observation indicated that the active principle is instable. These properties together with the wide distribution of the plant, its resistance and adaptation to the tropical climate, its easy cultivation and the easy obtention of latex and preparation of the molluscicidal solution, make this a promising material for large-scale use in the control of schistosomiasis

Toxicological study of the molluscicidal latex of Euphorbia splendens: irritant action on skin and eye

Aqueous solutions of the molluscicidal latex of Euphorbia splendens are irritant to the rabbit eye in concentrations higher than 0.35% and to the rabbit skin in concentrations higher than 0.5%. Although this irritant potential does not proclude its use as a molluscicide, special precautions are recommended for hanbdling and application of the product and the hazard of skin tumor-promoting potencial should be carefully investigated before its use for schistosomiasis vector control.

Evaluation of the genotoxic activity and acute toxicity of Euphorbia splendens latex, a molluscicide for the control of Schistosomiasis

The latex of euphorbia splendens var. hislopii has a molluscicidal action at low concentration (LD90 less than 1.5 ppm or 1.5 */ml) against the vector snails of schistosomiasis. In the present study, the latex in natura or after lyophilization was submitted to the Ames test and the chromotest to evaluate genotoxicity, to the Microtox System to determine acute toxicity, and to the Chinese hamster ovary cell assay (CHO) to measure cytotoxicity. The latex had no mutagenic activity in the presence or absence of S9 toward the TA98 and TA100 strains of Salmonella typhimurium (Ames test) at concentration up to 200 */plate (in natura) and of 200 *g/plate (lyophilized). The lyophilized latex had no genotoxic activity (Chromotest) and acute toxic effect on Photobacterium phosphoreum at concentrations up to 445 *g/ml, whereas the sample in natura had a toxic effect with an EC50 of 148,000 *l/l (or ppm). In the CHO/cytotoxicity assay, the lyophilized latex had no cytotoxicit effect in quantities up to 200 *g. The latex was found to have no acute toxicity or mutagenic at the concentrations of 10 to 12 *g/ml (or ppm) that are being proposed for molluscicidal use in the field