Natural Molluscicide Research Articles

Molluscicidal Activity and Inhibition of Acetylcholinesterase Activity of Azadirachta Indica Extract on Pomacea Canaliculata

The Golden Apple Snail, Pomacea canaliculata, is a notorious pest in Malaysia, leading to substantial agricultural and economic losses, while, the neem tree, Azadirachta indica has been identified as alternative source for bio-pesticides. There is currently limited information on A. indica as natural molluscicide against P. canaliculata. This study aims to evaluate the effects of A. indica on P. canaliculata at various life stages (eggs, juvenile and adult). The bioactive compound, azadirachtin in A. indica extracts was quantified using high-performance liquid chromatography (HPLC). Egg hatchability was determined using spot spraying on egg clusters while the molluscicidal activity of A. indica on juvenile and adult specimens was evaluated using the immersion bioassay approach. The snail's acetylcholinesterase (AChE) inhibition was assessed using Ellman assay. The azadirachtin content in the ethanolic extract of A. indica leaves at a concentration of 1 µg/mL was found to be 45.42%. Increasing the concentration of A. indica extracts resulted in lower egg hatchability and increased mortality of juvenile and adult snails. Azadirachta indica extracts showed the highest effectiveness against adult P. canaliculata with an LC50 value of 0.52 mg/mL, compared to 0.92 mg/mL for juveniles and 0.74 mg/mL for eggs. Additionally, A. indica extract exhibited greater inhibition of AChE in adult specimens compared to juvenile specimens and eggs. The IC50 for adult is 0.60 μg/mL, which is the lowest while the IC50 for juvenile is 0.68 μg/mL, the highest. Taken together, A. indica shows immerse potential as natural pesticide for managing the population of P. canaliculata.

Potential molluscicidal activity of the aqueous extracts of some plants and their powders against terrestrial snail Monacha obstructa (L. Pfeiffer, 1842) under laboratory and field conditions

As it is known that the excessive use of pesticides causes many environmental problems, the effects of four aqueous plant extracts and their powders [Solanum nigrum L., Withania somnifera (L.) Dunal, Salix mucronata Thunb. and Lawsonia inermis L.] were evaluated as natural molluscicides on the land snail Monacha obstructa (Family: Hygromiidae) under laboratory conditions. Three different bioassay methods were used: contact, leaf-dipping and bait techniques. The results indicated that, using all methods, S. Nigrum extract was the most toxic extract for the terrestrial snail M. obstructa. The contact technique of the tested plant extracts was the most effective method of application compared to other methods. Moreover, using plant extracts was better than using powders of these plants for controlling the terrestrial snail M. obstructa. In addition, the results indicated that the aqueous extract of S. nigrum gave the highest percentage of reduction in the snail population when assessed under field conditions. The obtained data showed that plant extracts were significantly effective against the terrestrial snail and could be used as alternatives to pesticides in integrated pest management.

Citrus limon as A Natural Molluscicide against Eobania vermiculata and Monacha cartusiana Snails

Citrus limon as A Natural Molluscicide against Eobania vermiculata and Monacha cartusiana Snails

Chinese Spinach (Amaranthus viridis Linn.) as Natural Molluscicide Against the Hatchability of Golden Apple Snail (Pomacea canaliculata Lamarck) Eggs

Chinese Spinach (Amaranthus viridis Linn.) as Natural Molluscicide Against the Hatchability of Golden Apple Snail (Pomacea canaliculata Lamarck) Eggs

Evaluating the Effectiveness of Acremonium sp. Protease as a Natural Molluscicide Agent: A Toxicological and Histological Investigation on Land Snails

Evaluating the Effectiveness of Acremonium sp. Protease as a Natural Molluscicide Agent: A Toxicological and Histological Investigation on Land Snails

Essential Oil Variability of Azorean Cryptomeria japonica Leaves under Different Distillation Methods, Part 2: Molluscicidal Activity and Brine Shrimp Lethality

This study reports on the in vivo molluscicidal activity and Artemia salina lethality of Azorean Cryptomeria japonica leaf (CJL) essential oils (EOs) obtained by hydrodistillation (HD) and water-steam distillation (WSD) techniques, especially in light of the recent focus on the use of forestry and wood industry residues in a sustainable world economy. Molluscicidal activity was performed during several life stages of Radix peregra by the immersion method, under laboratory conditions. A first screening through a single-dose bioassay revealed that both EOs were highly active towards eggs, juveniles and adult snails (ca. 100% mortality). Concentration- and time-toxicity assays were carried out only on adult snails to determine the lethal parameters (LC50;90 and LT50;90). The LC50 values were 33 and 62 µg/mL for EO–WSD and EO–HD, respectively, after 48 h. The LT50 of EO–WSD required only 21 h for both 16 h and continous exposure periods, while that of EO–HD was slighty superior (21.8–25.6 h). Although not significant, EO–WSD was also slightly more toxic against A. salina than EO–HD (LC50 = 98 and 115 µg/mL after 24 h, respectively). In conclusion, Azorean CJL EOs, which are rich in α-pinene (mostly EO–WSD), have huge potential to be used as safe raw materials for the development of natural molluscicide products to control snails responsible for transmitting fascioliasis.

Bio-molluscicidal potential and biochemical mechanisms of clove oil and its main component eugenol against the land snail, Theba pisana

The land snail, Theba pisana is a serious pest that adversely affects various crops in sustainable agriculture. Essential oils and their constituents represent an environmentally sound alternative to synthetic pesticides. Our study aimed to investigate the lethal and sub-lethal toxicity of clove oil and its main component eugenol to understand the mechanisms underlying its toxic action against T. pisana. The GC–MS profile of the clove oil composition was characterized. In the laboratory experiment, LD50 of clove oil and eugenol via the contact testing were determined after 48 and 72 h. Moreover, sub-lethal effects of clove oil or eugenol on the survivors following the exposure of snails to the 25 and 50% of the LD50/48 and 72 h were evaluated through using snail tissues for biochemical measurments. The GC–MS analysis showed that eugenol (64.87%) was the major constituent present in the oil. The results also showed that LD50 values at 48 and 72 h were 2006.5 and 1493.5 μg/g b.w for oil and 239.6 and 195.3 μg/g b.w for eugenol, respectively. Compared to control, the sub-lethal effects of clove oil or eugenol at 48 and 72 h showed a significant increase in reduced glutathione (GSH) levels. Catalase (CAT) and glutathione-S-transferase (GST) activities significantly elevated in oil- or eugenol-treated snails, except at low dose after 48 h. After two exposure times, snails exposed to oil or eugenol at both sub-lethal effects had considerably higher γ-glutamyltransferase (γ-GT) and aspartate aminotransferase (AST) activities. Moreover, markedly augmentation in alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activities at all exposure times, with the exception of snails treated with low dose of eugenol after 48 h was observed. Both clove oil and eugenol at the tested doses caused a significant inhibition in acetylcholinesterase (AChE) activity at two exposure times. Our findings highlight the potential of clove oil and eugenol, as an efficient natural molluscicide alternative to its synthetic counterparts for snail control.

Effect of Eucalyptus globulus oil and Ricinus communis methanolic extract as potential natural molluscicides on the reproductive biology and some antioxidant enzymes of the land snail, Theba pisana

This study was conducted to investigate the effects of Eucalyptus globulus oil and methanolic extract of Ricinus communis seeds on the reproductive biology of the land snail Theba pisana. For this purpose, the snails were exposed to different concentrations of these plant extracts for six weeks. Rates of oviposition, hatching percentages, reproductive hormones and the histological structures of the hermaphrodite gland were estimated. Antioxidant enzymes were also estimated. The obtained results revealed that all tested concentrations of both tested natural products exerted hazardous effects on exposed snails. The mean egg number/snail treated with 2% E. globulus and R. communis were significantly decreased to 22 and 14 eggs respectively compared to 79 eggs for control. The hatching rates were dramatically decreased with increasing concentrations of both products. 2% of R. communis extract caused highly significant decrease in the activities of CAT, SOD, GST and MDA antioxidant enzymes while the same concentration of Eucalyptus oil resulted in elevations of CAT and SOD activities and significantly decreased GST and MDA activities. Levels of reproductive hormones were greatly disrupted and the histological structures of hermaphrodite acini as well as various developmental stages of spermatogenesis and oogenesis of treated snails were strictly spoiled.

Reproductive alterations of Biomphalaria glabrata (Say, 1818) infected with Angiostrongylus cantonensis (Chen, 1935) and exposed to Euphorbia milii var. hislopii latex.

The natural phytochemical latex of Euphorbia milii var. hislopii is one of the most promising natural molluscicides for the control of Biomphalaria glabrata, and has been widely studied under laboratory conditions for selective control of schistosomiasis transmission. However, the effect of this product on B. glabrata infected by other helminths had not yet been investigated. The present study reports evaluation of the effect of E. milii var. hislopii latex on the survival and reproductive activity of B. glabrata infected by Angiostrongylus cantonensis. For this purpose, the following groups were formed: control (C), exposed (E), infected (I) and infected and exposed for different time intervals (1 day - I+E-1D, 7 days - I+E-7D, 14 days - I+E-14D, 21 days - I+E-21D and 28 days - I+E-28D). The experimental infection was performed with L1 larvae of A. cantonensis and exposure to 0.08 mg/L (LC50) of E. milii latex for a period of 24 hours. We analyzed the effects of E. milii latex on the survival of snails during four weeks, reproductive parameters and possible histophysiopathological changes in the gonad and albumen gland of the snails. Regarding survival, there was reduction of more than 50% in the groups exposed to latex (E and I + E) compared to the control group. As for the number of ovigerous masses, eggs, and average number of hatched snails, significant increases were observed in the I+E-1D group at the 4th week compared to the control group and the other weeks in the same group. Angiostrongylus cantonensis larvae were observed in the gonad and albumen gland from day 21 and 28 of infection in groups I and I+E, respectively, with granuloma-like formation. At these observation periods and in these groups, an increase in galactogen was observed in the albumen gland, which influenced egg laying, suggesting the existence of a fecundity compensation mechanism phenomenon. It was possible to conclude that both stressors - A. cantonensis infection and exposure to E. milii latex - directly influenced the survival and reproductive parameters of B. glabrata.

Anti-mollusk Selectivity of Jayanti Plant (Sesbania sesban L., Merr) for the Control of Golden Snails, a Pest of Paddy

Pest control is an essential aspect of rice cultivation. The golden snail (Pomacea speciosa) is one of the pests in rice fields. Damage to rice plants due to golden snail attacks has occurred in several provinces in Indonesia and several countries such as the Philippines, Thailand, Japan, and Malaysia. Various steps to control golden snails have been carried out, both mechanically, biologically, and chemically. However, each biological and mechanical control of golden snails is impractical to apply to very large rice fields. Meanwhile, the control of golden snails using synthetic molluscicides such as Brestan and Dimotrin is minimal because it can pollute the environment and cause the death of fish and the rice plant itself. To suppress the emergence of environmental pollution problems in overcoming this golden snail, natural molluscicides from plant materials are studied. Several plant species have been known to have anti-mollusk properties, one of which potentially is the Jayanti plant {Sesbania sesban (L.) Merr.}. This study aimed to evaluate the anti-mollusk performance of S. sesban for controlling golden snails, a pest of rice plants. The dry powder of S. sesban leaves was extracted in stages with a series of solvents of petroleum ether, chloroform, and ethanol to obtain an extract fraction that was selected as a mollucicide. Each extract fraction produced was tested for its toxicity to the gold snail, carp, rice germination, and rice plant growth. Data on the mortality of golden snail and carp fish, the percentage of germination inhibition, and rice growth were processed by probit analysis, respectively. The outputs of the analysis were LC50 of each extract fraction for golden snails and carp. The ratio of LC50 for golden snail with LC50 for carp indicated each extract fraction's physiological selectivity of anti-mollusk properties. The results showed that the highest lethal toxicity to gold snails was indicated by the extract fraction-ethanol, while to carp, it was indicated by the extract fraction-chloroform. Each extract fraction of S. sesban leaves did not inhibit the germination and growth of rice plants. The extract fraction- ethanol had the highest anti-mollusk selectivity compared to the other two fractions. Bioactive examination showed triterpene saponins from the extract of S. sesban leaves, with the highest relative levels in the ethanol fraction compared to the other two extract fractions.

Essential oils of the leaves of Syzygium cumini (L.) Skeels and fruit peels of Hymenaea courbaril (L.) var. courbaril as molluscides against Biomphalaria glabrata

This study evaluated the molluscicidal activity of essential oils (EOs) of Syzygium cumini L. and Hymenaea courbaril L. Hydrodistillation was used to extract the EOs. The chemical characterization was performed by Gas Chromatography coupled to mass spectrometry. The bioassay of Artemia salina Leach was used for the toxicity test. The molluscicidal assay tested concentrations of 10-80 mg L-1 of the EOs against Biomphalaria glabrata. The major constituent of The EO of S. cumini was isokaryophyllene and H. courbaril the Germacreno-D. The toxicity assay classified The EOs as nontoxic with LC50 412.10 mg L-1 for S. cumini and LC50 354.80 mg L-1 for H. courbaril. The molluscicidal assay purchased LC50 44.76/ LC90 77.20 for S. cumini and LC50 37.34 mg L-1/ LC90 73.24 mg L-1 for H. courbaril. The results showed that both EOs can be used as natural molluscicides in combating the snail Biomphalaria glabrata.

Marrubium vulgare L.: A Phytochemical and Pharmacological Overview.

Marrubium vulgare is a plant with high bioactive potential. It contains marrubiin, a labdane diterpene that is characteristic for this genus, as well as a complex mixture of phenolic compounds. According to numerous studies, M. vulgare acts as a good antioxidant agent, and due to this, it could potentially be useful in treatments of cancer, diabetes mellitus, and liver diseases. In addition, its anti-inflammatory, wound-healing, antihypertensive, hypolipidemic, and sedative potential are discussed. Apart from that, its antimicrobial activity, especially against Gram+ bacteria, fungi, herpes simplex virus, and parasites such as Toxoplasma gondii, Trichomonas vaginalis, and Plasmodium berghei-berghei was recorded. Additionally, it could be used as a chicken lice repellent, herbicide, and natural insecticide against mosquito larvae and natural molluscicide. In veterinary medicine, M. vulgare can be used as an anthelmintic against the eggs and larvae of bovine strongyles parasites, and as an antibiotic against bovine mastitis caused by resistant bacterial strains. Due to the mentioned benefits, there is a tendency for the cultivation of M. vulgare in order to ensure high-quality raw material, but more firm scientific evidence and well-designed clinical trials are necessary for the well-established use of M. vulgare herb and its preparations.

Development of a natural molluscicide prototype kit (MoluSchall) for the control of schistosomiasis mansoni transmission.

In Brazil, Biomphalaria glabrata, B. tenagophila, and B. straminea are intermediate hosts of Schistosoma mansoni, the etiological agent of schistosomiasis mansoni. Molluscicide use is recommended by the WHO for controlling the transmission of this parasite. Euphorbia milii latex has shown promising results as an alternative molluscicide. Thus, a natural molluscicide prototype kit based on freeze-dried E. milii latex was developed and evaluated against Biomphalaria spp. E. milii latex was collected, processed, and lyophilized. Two diluents were defined for freeze-dried latex rehydration, and a prototype kit, called MoluSchall, was produced. A stability test was conducted using prototype kits stored at different temperatures, and a toxicity assay was performed using Danio rerio. Additionally, MoluSchall was tested against B. glabrata under semi-natural conditions according to defined conditions in the laboratory. MoluSchall was lethal to three Brazilian snail species while exhibiting low toxicity to D. rerio. Regardless of storage temperature, MoluSchall was stable for 24 months and was effective against B. glabrata under semi-natural conditions, with the same LD100 as observed under laboratory conditions. MoluSchall is a natural, effective, and inexpensive molluscicide with lower environmental toxicity than existing molluscicides. Its production offers a possible alternative strategy for controlling S. mansoni transmission.

Chemical Characterization and Molluscicidal Activity of Essential Oil from Leaves of Eugenia uniflora L. on Lymnaea columella (Say, 1817) and Biomphalaria tenagophila (D’Orbigny, 1835)

Aiming to find compounds of natural origin that present molluscicide activity, essential oil from leaves of Eugenia uniflora L. (Brazilian cherry tree) was obtained by steam distillation in a Clevenger type apparatus and evaluated on Lymnaea columella, an intermediate host of the parasite Fasciola hepatica, and Biomphalaria tenagophila, an intermediate host of the parasite Schistosoma mansoni. For chemical characterization, the E. uniflora L. essential oil was analyzed by gas chromatography with flame ionization detector (GC-FID) and by mass spectrometry (GC-MS). The major components found were: (-)-selina-1,3,7(11)-trien-8-one (25.0%) and oxidoxelina-1,3,7(11)-trien-8-one (22.1%). The LD100 value was 100ppm for L. columella and 60 ppm for B. tenagophila. These concentrations are within the parameters recommended by the WHO. In addition to the molluscicidal effect, at a concentration of 20 ppm the E. uniflora L. essential oil presented an inhibitory effect on the oviposition of the two species evaluated. In this way, essential oil from E. uniflora L. leaves presented potential for use as a natural molluscicide to control of L. columella and B. tenagophila.

Double impact: natural molluscicide for schistosomiasis vector control also impedes development of Schistosoma mansoni cercariae into adult parasites.

BackgroundSchistosomiasis has been reported in 78 endemic countries and affects 240 million people worldwide. The digenetic parasite Schistosoma mansoni needs fresh water to compete its life cycle. There, it is susceptible to soluble compounds that can affect directly and/or indirectly the parasite’s biology. The cercariae stage is one of the key points in which the parasite is vulnerable to different soluble compounds that can significantly alter the parasite’s life cycle. Molluscicides are recommended by the World Health Organization for the control of schistosomiasis transmission and Euphorbia milii latex is effective against snails intermediate hosts.Methodology/Principal findingsWe used parasitological tools and electron microscopy to verify the effects of cercariae exposure to natural molluscicide (Euphorbia milii latex) on morphology, physiology and fitness of adult parasite worms. In order to generate insights into key metabolic pathways that lead to the observed phenotypes we used comparative transcriptomics and proteomics.Conclusions/SignificanceWe describe here that the effect of latex on the adult is not due to direct toxicity but it triggers an early change in developmental trajectory and perturbs cell memory, mobility, energy metabolism and other key pathways. We conclude that latex has not only an effect on the vector but applies also long lasting schistosomastatic action. We believe that these results are of interest not only to parasitologists since it shows that natural compounds, presumably without side effects, can have an impact that occurred unexpectedly on developmental processes. Such collateral damage is in this case positive, since it impacts the true target of the treatment campaign. This type of treatment could also provide a rational for the control of other pests. Our results will contribute to enforce the use of E. milii latex in Brazil and other endemic countries as cheap alternative or complement to mass drug treatment with Praziquantel, the only available drug to cure the patients (without preventing re-infection).

Histopathological Changes in Tissues of Bithynia siamensis goniomphalos Incubated in Crude Extracts of Camellia Seed and Mangosteen Pericarp

The present study was performed to observe histopathological changes in tissues of Bithynia siamensis goniomphalos (Gastropoda, Bithyniidae) incubated in crude extract solutions of camellia (Camellia oleifera) seed and mangosteen (Garcinia mangostana) pericarp, and furthermore to estimate the molluscicidal effects of 2 plant substances. Substantial numbers of bithyniid snails were incubated in various concentrations of 2 plant solution for 24 hr. As the positive control, snails incubated in various concentrations of niclosamide, a chemical molluscicide, were used. The histopathological findings were observed in sectioned snail specimens of each experimental and control groups. The results showed that both camellia and mangosteen extracts had molluscicidal effects at 24 hr with 50% lethal concentration (LC50) at concentrations of 0.003 and 0.002 g/ml, respectively, while niclosamide had LC50 at concentrations 0.599 ppm. B. siamensis goniomphalos snail tissues (foot, gill, and digestive system) showed disruption of columnar muscle fibers of the foot, reduction of the length and number of gill cilia, numerous mucous vacuoles, and irregularly shaped of epithelial cells. Irregular apical and calciferous cells, dilatation of the digestive gland tubule, and large hemolymphatic spaces, and irregular apical surfaces, detachment of cilia, and enlargement of lysosomal vacuoles of epidermis were also shown in all groups. By the present study, it is confirmed that 2 plants, camellia and mangosteen, are keeping some substance having molluscicidal effects, and histopathological findings obtained in this study will provide some clues in further studies on their action mechanisms to use them as natural molluscicides.

Schistosomiasis Control Using Piplartine against Biomphalaria glabrata at Different Developmental Stages

BackgroundSchistosomiasis is one of the most significant diseases in tropical countries and affects almost 200 million people worldwide. The application of molluscicides to eliminate the parasite's intermediate host, Biomphalaria glabrata, from infected water supplies is one strategy currently being used to control the disease. Previous studies have shown a potent molluscicidal activity of crude extracts from Piper species, with extracts from Piper tuberculatum being among the most active.Methods and FindingsThe molluscicidal activity of P. tuberculatum was monitored on methanolic extracts from different organs (roots, leaves, fruit and stems). The compounds responsible for the molluscicidal activity were identified using 1H NMR and ESIMS data and multivariate analyses, including principal component analysis and partial least squares. These results indicated that the high molluscicidal activity displayed by root extracts (LC50 20.28 µg/ml) was due to the presence of piplartine, a well-known biologically-active amide. Piplartine was isolated from P. tuberculatum root extracts, and the molluscicidal activity of this compound on adults and embryos of B. glabrata was determined. The compound displayed potent activity against all developmental stages of B. glabrata. Next, the environmental toxicity of piplartine was evaluated using the microcrustacean Daphnia similis (LC50 7.32 µg/ml) and the fish Danio rerio (1.69 µg/ml). The toxicity to these organisms was less compared with the toxicity of niclosamide, a commercial molluscicide.ConclusionsThe development of a new, natural molluscicide is highly desirable, particularly because the commercially available molluscicide niclosamide is highly toxic to some organisms in the environment (LC50 0.25 µg/ml to D. similis and 0.12 µg/ml to D. rerio). Thus, piplartine is a potential candidate for a natural molluscicide that has been extracted from a tropical plant species and showed less toxic to environment.

Atividade moluscicida de plantas: uma alternativa profilática

Uma das formas de combate a helmintos que possuem moluscos em seu ciclo biologico e o controle da populacao malacologica. A tentativa de combater os criadouros naturais de hospedeiros intermediarios, atraves de moluscicidas, tem sido uma das formas almejadas para a reducao da incidencia de enfermidades, como as esquistossomoses e fascioloses. Essa medida epidemiologica tem se concretizado atraves da utilizacao dos moluscicidas sinteticos que, dentre outras desvantagens, trazem danos ao ecossistema. Visando a obtencao de novos compostos, os estudos sobre a potencialidade de produtos naturais moluscicidas tem crescido consideravelmente. Alguns pesquisadores apontam os moluscicidas vegetais como fontes alternativas para o tratamento profilatico de parasitoses. Tendo em vista a abrangencia, endemicidade e relevância, este trabalho revela um maior enfoque a atividade moluscicida de plantas relacionada as esquistossomiases.

Use of a Saponin Based Molluscicide to Control Pomacea canaliculata Snails in Southern Brazil

Pomacea canaliculata snails pose a severe problem to direct seeded rice cultivated in Southern Brazil. Control of this snail is nowadays performed with toxic chemicals such as copper sulfate and fungicides such as fentin. A novel natural molluscicide based on alkali modified quinoa (Chenopodium quinoa) saponins was tested under laboratory conditions. Snails were collected in rice fields close to Porto Alegre (State of Rio Grande do Sul) and in Brusque (State of Santa Catarina, 400 km north of Porto Alegre). In Santa Catarina the product was very effective, while in Porto Alegre it had no effect. This unexpected behavior was probably due to the respiratory habits of the snails under different contents of dissolved oxygen in the water. Near Porto Alegre the water used in rice fields is heavily polluted, with dissolved oxygen levels of 1-2 ppm, and the snails rely primarily on their siphon and lungs to breathe. Since saponin control is probably due to an interaction between saponins with the sterols present in the cell walls in the gills, no control was observed. By contrast, in Santa Catarina the dissolved oxygen level of the water is 5-6 ppm, and the snails remain mostly underwater, breathing with their gills. In this case the snails died within 24 h at a dose of 20 and 30 ppm of product. To test this observation, snails grown in polluted waters were forced to remain underwater in saponin solutions and water (control) preventing the use of their siphon to breathe. The snails exposed to saponin solutions died, while the control snails survived, indicating that they were still able to use their gills to breathe. These results indicate that the use of the saponin product is limited to rice fields not irrigated with heavily polluted waters.

Atividade de Stryphnodendron polyphyllum, uma planta do cerrado do Brasil, contra hemócitos de Biomphalaria glabrata, um hospedeiro intermediário de Schistosoma mansoni.

The snail Biomphalaria glabrata acts as an intermediate host to Schistosoma mansoni, an endemic parasite in several countries. B. glabrata hemocytes are related to its defense against infection by trematodes, including S. mansoni. In the present paper, the activity of molluscicidal substances such as the tannic acid extracts of Stryphnodendron polyphyllum, a plant from the Brazilian Savannah, on the morphology and number of B. glabrata hemocytes was evaluated. The bark and leaf extracts of S. polyphyllum were diluted in dechlorinated water and groups of snails were exposed to 25 and 50 mg.L-1 concentrations of the extracts, as well as, to tannic acid during 24h. Subsequently, hemolymph was removed from the pericardic region. Hemocyte subpopulations were detected and classified as small (5.0 – 6.9 ?m), medium (7.0 – 8.9?m), large (9.0 – 12.0?m) and giant (over 12?m), the latter being a novel classification. The extracts stimulated an increase in the number of hemocyte cells in the hemolymph. This is understood as a defense mechanism against toxic substances such as tannic acid, present in high levels in both tested extracts. Hemocytes showed vacuoles in the cytoplasm due to the presence of such substances, which are signs of cellular death due to apoptosis. We conclude that the extracts are highly effective against B. glabrata, recommending further biological impact studies aiming its use as a natural molluscicide.