Synthetic Molluscicides Research Articles

Molluscicidal activity of Nigella sativa seed, Azadirachta indica leaf and Khaya senegalensis bark ethanolic extracts against Bulinus truncatus snails

In order to control schistosomiasis, a strategy involves eliminating the intermediate host responsible for its transmission. Plant-derived molluscicides have been extensively researched as a cost-effective approach to combat this disease, seeking alternative solutions to synthetic molluscicides. The study aimed to analyze the phytoconstituents and assess the molluscicidal impact of ethanolic extracts on adult Bulinus truncatus snails. Dried plant materials were ground into powder, and then extracted using ethanol 96%. Preliminary phytochemical screening was carried out using standard procedures. In vitro Molluscicidal activity was evaluated for the three plants extracts in different concentrations (125, 250, 500 and 1000 ppm). Every 5 adult snails were placed in a plastic cup containing a specific amount of dechlorinated water with plant sample. Control negative was prepared by placing the snails in dechlorinated water only, the numbers of survived and dead snails were recorded after 24 and 48 hours. The Lethal dose and Standard deviation were calculated. The phytochemical screening revealed the presence of different chemical constituents in the three plants samples. The result showed that all the plants extracts possessed molluscicidal activity against B. truncatus snails. The A. indica leaf extract was the most effective with LD50 of 74.32544 ppm. From the findings of this study, Molluscicide of plant origin could be useful against the common snail species in Sudan; therefore, the selected plants can play a big role in community based Schistosomiasis control.

Analysis of Achyranthes aspera leaf extract and acute toxicity study on fingerlings of Nile tilapia, Oreochromis niloticus

Schistosomiasis is a debilitating chronic disease with great socioeconomic and public health impact affecting the poor rural populations who lack access to sanitation, and safe water supply. The high cost of synthetic molluscicides, their toxicity to non-target organisms, and their persistence in the environment have forced the research of plant-derived molluscicides. Although plant molluscicides are cheap, biodegradable, ecofriendly and less toxic to higher animals, unregulated applications could affect non˗target organisms. Therefore, ecotoxicological studies are essential to assess the toxicity of these substances to economically and ecologically significant fish species and to establish safe dosage level. This study is intended to investigate the acute toxicity of a molluscicidal plant Achyranthes aspera to Nile tilapia fingerlings, Oreochromis niloticus (O. niloticus) (n = 7) were exposed to serial dilutions of A. aspera leaf aqueous extract using maceration method for 96 h in triplicate setup. Phytoconstituents were identified by GC-MS. Mortality data were analyzed by probit regression to determine lethal concentrations. The NOAEC was ascertained through hypothesis testing based on survival data. The respective piscicidal LC1 and LC10 values were 897.43 and 1063.87 mg/L while the LC50 is 1310.74 mg/L. In addition, the NOAEC was 1100 mg/L (p > 0.05). This piscicidal toxicity is much lower than its molluscicidal potency may be due to the presence of rotenones and triterpenoides which are commonly found in piscicidal natural products. The GC-MS analysis revealed 12 phytoconstituents including a monoterpene. This study indicates that A. aspera has low toxicity to Nile tilapia could be due to monoterpenes are nontoxic. The findings of this study demonstrate that, at this dose, the plant is safe to the test fish. Thus it can be effective, eco-friendly and sustainable alternative for the development of molluscicides for snail control.

Chemical composition, larvicidal and molluscicidal activity of the essential oil Alpinia zerumbet

In this present study, we describe the chemical composition, larvicidal and molluscicidal activity of essential oil distilled from Alpinia zerumbet leaves against third-stage larvae of Ae.aegypti and the snail Biomphalaria glabrata, respectively. For this, we distilled the oil by hydrodistillation, identified its components by gas chromatography coupled to mass spectrometry and gas chromatography with flame ionization detection and calculated the lethal concentration of larvicidal and molluscicidal activity using the probit method. From these analyses, we showed that the oil is predominantly composed of monoterpenes, in which p-cymene (34.12%), 1,8-cineole (25.67%) and terpinen-4-ol (21.01%) stood out. In addition, we also proved that the oil has larvicidal and molluscicidal activity with lethal concentrations respectively of 43.74 and 36.52 μg/mL. Therefore, we conclude that the oil is active and has the potential to replace synthetic larvicides and molluscicides.

Molluscicidal activity of plant alkaloids.

Some snail species pose a serious threat for human health, economy, and the environment due to their widespread distribution and the transmission of dangerous parasites causing, among others, schistosomiasis and fascioliasis. Scientists from around the world have been studying the effects of plant extracts on snails for many years in order to find an alternative to molluscicides of synthetic origin. The main purpose of this study was to collect the results obtained so far on the effect of plant alkaloids on snails in the context of their molluscicidal properties. This work presents the results of publications on the effect of plant alkaloids on snails, which were published in the years 1974-2021. The Solanaceae, Papaveraceae, and Asteraceae are the plant families most frequently cited for containing alkaloids with molluscicidal activity. The alkaloids identified as molluscicidal belonged to various groups, of which the most numerous were pseudoalkaloids and tyrosine-derived alkaloids. Most of the tested alkaloids were characterized by a high mortality rate among the studied groups of snails. Based on the collected research results, it was found that plant alkaloids can be extremely useful in the fight against problematic species of snails and cause much lower harm to the environment than synthetic molluscicides.

Fumigant Toxicity and Feeding Deterrent Activity of Essential Oils from Lavandula dentata, Juniperus procera, and Mentha longifolia against the Land Snail Monacha obstructa

Land mollusks are one of the most destructive agricultural pests worldwide, the management of which depends on synthetic molluscicides. However, many of these molluscicides are harmful to nontarget organisms. Hence, there is a need to develop alternative ecofriendly molluscicides that are less impactful toward nontarget organisms. So, an investigation into the fumigant toxicity and feeding deterrent effect of essential oils (EOs) from Lavandula dentata L. (Lamiaceae), Juniperus procera Hochst. (Cupressaceae), and Mentha longifolia (L.) Huds. (Lamiaceae) against the land snail Monacha obstructa (Pfeiffer, 1842) (Hygromiidae) was performed. L. dentata EO exhibited the highest fumigant toxicity with LC50 values of 8.68 μL/L air and 7.24 μL/L air after 24 h and 48 h exposure periods, respectively. Its main components were camphor, 1,8-cineole, fenchone, and β-myrecene. The fumigant toxicity of J. procera EO was lower than that of L. dentata, with LC50 values of 25.63 μL/L air and 20.11 μL/L air after 24 h and 48 h exposure periods, respectively. The major constituents of J. procera EO were α-pinene, p-cymene, and β-ocimene. The analysis of M. longifolia EO showed that pulegone, and menthol were the major constituents. However, it displayed no fumigant toxicity up to 50 μL/L air. The three EOs exhibited a strong feeding deterrent effect at sublethal concentrations. The EOs extracted from L. dentata, J. procera and M. longifolia are promising ecofriendly botanical molluscicides against the land snail M. obstructa.

Immunotoxical, neurotoxical, histopathological and immunohistopathological alterations of Nerium oleander and Tecoma stans methanolic extract on Biomphalaria alexandrina snails

Schistosomiasis is a severe illness that caused socioeconomic problems. The present study aimed to investigate the molluscicidal activities of the methanolic extract of Nerium oleander and Tecoma stans on B. alexandrina snails. The present results showed that N. oleander had the higher molluscicidal effect (LC50: 138.6 mg/l) than T. stans methanolic extract (LC50: 256.0 mg/l). These concentrations had no mortality effects on Daphnia magna during the first 12 h of the exposure, while, they had a cercaricidal activity. Exposure of B. alexandrina snails to the sub lethal concentrations (LC10 and LC25) of the methanolic extract of either N. oleander or T. stans caused a concentration- dependent significant decrease in their mean total number of hemocyte and hyalinocytes percent, while, both the round small and the granulocytes were increased than the control group. Exposure of B. alexandrina snails to LC25 of the methanolic extract of N. oleander or T. stans, caused morphological alterations in the hemocytes that were studied by both light and electron microscopy. The sub lethal concentration (LC25) significantly decreased the acetyl cholinesterase activities, acid and alkaline phosphatase levels and the protein content. Histopathological changes occurred in the digestive and the hermaphrodite glands of exposed B. alexandrina snails to LC25 of the methanolic extracts. These alterations were confirmed by Immunohistochemistry for PCNA and Cyclin D1 expressions. Conclusively, these plants could be used to decrease the spread of schistosomiasis as they are cheap and environmentally safe to replace the synthetic molluscicides for snail control.

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.

Molluscicides against the snail-intermediate host of Schistosoma: a review.

Schistosomiasis, a neglected tropical disease (NTD), is one of the most prevalent parasitoses in the World. Certain freshwater snail species are the intermediate host in the life cycle of schistosome species. Controlling snails employing molluscicides is an effective, quick, and convenient intervention strategy to prevent the spread of Schistosoma species in endemic regions. Advances have been made in developing both synthetic molluscicides and molluscicides derived from plants. However, at present, the development of molluscicides is not adapted to the actual demand for snails and schistosoma controlling. We undertake a systematic review of exploitation and application of synthetic molluscicides and molluscicides derived from plants to combat intermediate host snails. The detailed molluscicidal activity, structure–activity relationship, structural feature, and possible mechanism of some molluscicides are also highlighted, which may afford an important reference for the design of new, more effective molluscicides with low environmental impact and realize the aim of controlling schistosome at transmission stages.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00436-021-07288-4.

Relative efficacy of biological control and cultural management for control of mollusc pests in cool climate vineyards

ABSTRACT Restrictions on the use of synthetic molluscicides highlight the importance of developing alternative control methods. Nevertheless, biocontrol agents can be costlier and less effective than synthetic counterparts. One means of increasing the efficacy of population suppression is to combine inundative biological control with habitat management to reduce population growth of target pests. Vineyards in the cool, wet climate of western England can suffer from outbreak densities of mollusc pests that damage expanding shoots, developing grapes and promote the transmission of fungal pathogens. In this study we combined the biocontrol agent Nemaslug – Phasmarhabditis hermaphrodita (Schneider) – with a simple habitat management approach (regular mowing) to suppress mollusc pests in vineyards in South Western England. Two sites were treated with NemaSlug and or mowing in a factorial design in early spring coinciding with bud burst and the start of mollusc growth and feeding. Mowing was effective management and resulted in the reduction of slug and snail populations and significantly less damaged vines. Nemaslug did not reduce slug numbers overall but did reduce bud damage, snail numbers and lowered the proportion of susceptible Deroceras spp in treated plots. However, effect sizes of nematode biocontrol were small, potentially because this product could not be applied to bare soil. Management practice for cool climate vineyards varies considerably from site to site. This study shows the value of simple habitat management for controlling a novel target and emphasises how consideration of pest biology can lead to effective alternatives.

Response of grey slug to entomopathogenic nematodes

ABSTRACT Biological control using entomopathogenic nematodes (EPNs) is known as an ecofriendly strategy in integrated pest management. The terrestrial slug Parmacella ibera is a major pest of vegetables and citrus trees in north of Iran. The heavy costs and environmental concerns of synthetic molluscicides led the study to use EPNs, against the slug P. ibera. The present study was arranged to evaluate and compare the performance of EPNs, Steinernema feltiae, S. carpocapsae and Heterorhabditis bacteriophora on P. ibera population (mortality rate) and the feeding rate in vitro, and also its damage (seedlings establishment rate) in vitro. Phasmarhabditis hermaphrodita, as a slug parasite nematode, and also the metaldehyde, as a molluscicide, were used as positive controls. The results of the study showed that the highest mortality rate (%) and the seedlings establishment rate (%) of the slug population were observed in S. carpocapsae, S. feltiae and H. bacteriophora treatments, respectively. The feeding rate (%) of the slug declined in the treatments with H. bacteriophora, S. feltiae and S. carpocapsae, respectively. The mortality rate of the pest was enhanced by extending the exposure time and increasing levels of the nematodes. Therefore, it can be concluded that the EPNs S. carpocapsae, S. feltiae and H. bacteriophora are able to control the slug P. ibera population.

Comparison for the Efficacy of Column Purified Fractions of Sinna occidentalis and Moringa oleifera against Bulinus globosus (Intermediate Host of Schistosoma haematobium) from Goronyo and Shagari Dams, Sokoto State, Nigeria

Introduction: Although, used of molluscicides to control the intermediate host of schistosomes is the best method of choice to control the spread of the snail fever among the people, synthetic molluscicides widely used are cost effective, not available and toxic to the aquatic lives and people that are completely or partially dependents on rivers or lakes water for their everyday supplement.
 Aim: this research was aimed at investigation and comparison for the molluscicidal efficacy for S. occidentalis and M. oleifera leaves extracts against B. globosus (intermediate host of Schistosoma haematobium).
 Methodology: Each of the plant was grinded into powder and purified through column using different solvents, B. globosus snails were collected from Shagari and Goronyo dams; we identified the animal using chart initially, later on the animals were confirmed as B. globosus by malacologist from Ahmadu Bello University Zaria, Nigeria; the Molluscicidal efficacy of the plants was tested against B. globosus and compared according to world health organization guidelines; mortality was calculated using Abbort’s formula and analysis of variance (ANOVA) was used to determine if there is significant different between the mean mortality at P<0.05; qualitative Phytochemical analysis was conducted to determine the chemicals presence in each plant and their combination.
 Results: Present study reviled that fractions of the leaves combination showed significantly higher mortality of B. globosus in the present study followed by Fractions of S. occidentalis then that of M. oleifera. For the plants combination, extracts purified using methanol are highly toxic followed by fractions purified using hexane, then ethyl acetate fractions and least Molluscicidal potential was recorded in the fractions obtained using ethanol. S. occidentalis fractions of hexane were highly toxic followed by fractions of methanol, then fractions of ethyl acetate and least mortality was recorded from the fractions of ethanol. Similarly, for the M. oleifera, it was observed that, fractions of Methanol were highly toxic followed by hexane fractions then ethanol fractions and least mortality was observed in the fractions of ethyl acetate.
 Conclusion: Column purified fractions for the combination for two plants leaves were highly potent for the control of B. globosus followed by S. occidentalis then M. oleifera.

Assessment of the molluscicidal activity of wormwood (Artemisia dubia, Wallich) leaves ethanolic extract on Oncomelania hupensis quadrasi, Möllendorff

This study assessed the in vitro molluscicidal activity of Artemisia dubia (wormwood) leaf ethanolic extract against adult and juvenile Oncomelania hupensis quadrasi and profiled its qualitative phytochemical content. The plants and snails were collected locally. There were 8 concentrations used for adult and juvenile snails: distilled water and 1% ethanol as negative controls; niclosamide (2 mg/L) as a positive control; and different concentrations of wormwood ethanolic extracts for adult snails including 3.98% (T1), 4.46% (T2), 5% (T3), 5.61% (T4), and 6.30% (T5) and for juvenile snails including 7.94% (T1), 8.91% (T2), 10% (T3), 11.22% (T4), and 12.59% (T5). Each treatment was replicated 5 times with 20 snails per replicate. Results showed that the concentrations that were statistically comparable with niclosamide (2 mg/L) were 6.30% (T5) with 92% mortality for adults and 10% (T3), 11.22% (T4), and 12.59% (T5) for juveniles with 94%, 95%, and 98% mortality, respectively (P > 0.05). The qualitative phytochemical tests for secondary metabolites revealed the presence of tannins, saponins, and terpenoids. Independently or in combination, these secondary metabolites may be responsible for the mortality of the snails. This study indicates the possibility of using wormwood ethanolic extract as a potent and a possible alternative for synthetic molluscicides.

Assessment of the molluscicidal impact of extracted chlorophyllin on some biochemical parameters in the nervous tissue and histological changes in Biomphalaria alexandrina and Lymnaea natalensis snails.

Biomphalaria alexandrina and Lymnaea natalensis snails are the intermediate hosts of schistosomiasis and fasciolosis. The aim of the present study is to evaluate the molluscicidal activity of chlorophyll extract as a photodynamic substance against these snails and how it affected its tissues and the biological system. Chlorophyllin was extracted from deep-frozen Moringa oleifera leaves, and then it was transformed into water-soluble chlorophyllin. The present results showed that it had a molluscicidal activity on B. alexandrina snails (LC5017.6mg/l; LC9020.9mg/l) and L. natalensis snails (LC504.3mg/l; LC906.8mg/l). Exposing B. alexandrina snails to the sublethal concentrations (LC0, LC10, and LC25) resulted in a significant reduction in their survival rates. Regarding its effect on biochemical parameters, chlorophyllin significantly reduced the acetylcholinesterase activity, protein content, and alkaline and acid phosphatase activity in B. alexandrina nervous tissue compared to the control group. Histopathological changes occurred in the digestive gland of treated B. alexandrina snails where cells lost their nuclei, vacuolated, degenerated, and ruptured, and the lumen increased. Photosynthesizing materials like chlorophyllin are new approaches to control schistosomiasis and fasciolosis in developing countries by affecting their intermediate host. These materials were cheap and environmentally safe to replace the synthetic molluscicides for snail control.

Development of a bait carrier material for apple snail (Pomacea maculata) based on its feed preferences using snail attractant tracking device

Background: Synthetic molluscicides are routinely used in the control of apple snails (Pomacea spp of Ampullariidae family), the invasive rice pest. Molluscicidal bait is a strategic combination of food and toxicant to attract the target pests. However, baits are found to be feed deterrent due to snails' own feed preferences in a paddy field. There is no specific feed formulation exclusively developed as the base carrier material for the development of molluscicidal bait for the apple snail (Pomacea maculata Perry). Further, there are limitations in evaluating the efficacy of a snail feed/bait formulation based on its attractiveness, palatability, and directional movement of snails with the existing experimental devices. Therefore, this study was aimed to develop an attractive and appetent feed formulation as a bait carrier material and also to design and develop a snail attractant tracking device (SATD) for evaluating the feed formulation precisely. Materials and Methods: Snails were collected from the snail-infested rice field located in Kedah, Malaysia. A glass aquarium tank of size 60 cm × 30 cm × 30 cm was physically partitioned to form four linear channels (tracks) using 5-mm thickness transparent perflex plastic sheets to develop SATD and snail feed formulations were evaluated with the help of it. Results: This study resulted in the development and evaluation of attractant feed formulations prepared with a combination of different types of carbohydrates and protein hydrolysates. Analysis of variance showed significant differences (P

Evaluation of the effect of some plant molluscicides on the infectivity of Schistosoma mansoni cercariae

Objectives To study the effect of sublethal concentrations (LC50) of methanol extracts from Solanum nigrum and Callistemon citrinus leaves on the infectivity of Schistosoma mansoni cercariae by an in-vivo study. Background The high cost of synthetic molluscicides and their negative impacts on the environment necessitated search for an alternative approach by using plant extracts for the control of schistosomiasis. Using molluscicides could be more effective if these agents also possess cercaricidal activity. Materials and methods Methanol extracts of S. nigrum and C. citrinus leaves were prepared and their LC50on S. mansoni cercariae were determined. The experimental mice used in this study were divided into three groups. Group I including mice infected with S. mansoni cercariae preexposed to S. nigrum. Group II included mice infected with S. mansoni cercariae preexposed to C. citirnus. Group III included mice infected with nonexposed S. mansoni cercariae (control group). The attenuating effect of the plants on cercariae was evaluated through different parameters including parasitological, histopathological, and scanning electron microscopic examinations. Results LC50of S. nigrum and C. citrinus methanol extracts were 25 and 40 mg/l, respectively. Parasitological results showed a significant reduction in worm burden, mean number of ova per gram tissue in mice of group I and group II in comparison with those of group III (control group). These results were associated with decrease in the size and number of hepatic granulomas. All these obtained results were more significant with S. nigrum than C. citrinus. Obvious tegmental damages were also detected by scanning electron microscopic in both groups (I and II). Conclusion Methanol extracts of both S. nigrum and C. citrinus leaves exhibited cercariicidal activity but S. nigrum was found to be more potent. This study provides a considerable scope in exploiting local indigenous resources for schistosomiasis control.

New Approach for Controlling Snail Host of Schistosoma mansoni, Biomphalaria alexandrina with Cyanobacterial Strains-Derived C-Phycocyanin.

Schistosomiasis is one of the major communicable diseases of public health and socioeconomic importance in the developing world. It is a waterborne disease in which Biomphalaria alexandrina snails are known to be the intermediate molluscan host for Schistosoma mansoni: the causative agent of human intestinal schistosomiasis. Therefore, snail control is one of the cornerstones of schistosomiasis control programs. Several methods have been used to eliminate snail hosts. One of these methods is chemical molluscicides, which have undesirable effect to nontarget organisms. Consequently, the search for biologically derived molluscicides to complement the use of synthetic molluscicides is a top priority. In this concern, this study is the first to evaluate the molluscicidal potency of Cyanobacterial Phycocyanin (C-PC) as a virtually untapped source. Laboratory assessment of three freshwater Cyanobacterial strains: Anabaena oryzae SOS13, Nostoc muscorum SOS14, and Spirulina platensis SOS13-derived C-Phycocyanin as a biocontrol agent against freshwater mollusks; B. alexandrina snails were performed. Also, the safety of tested C-PC on nontarget organisms (Tilapia fish) was assessed. Results reveal that C-PC extracted from all tested Cyanobacteria strains showed a promising molluscicidal activity (the mortality rate was 100% at 100 μg/mL concentration). Out of the examined strains, A. oryzae SOS13 phycocyanin was found to be the most potent strain (LC50 and LC90 were 38.492 and 49.976 μg/mL, respectively). Moreover, C-PC extracts from all tested strains have been found to be safe to Tilapia fish as the survival rate was 100% at the effective molluscicidal concentrations. We can conclude that C-PC extracts are the first promising microbial biopesticides for the control of freshwater B. alexandrina snails.

Toxicity of Euphorbia helioscopia pellets to two Phytophagous molluscs, Theba pisana Müller, 1774 (Pulmonata: Helicidae) and Arion hortensis férussac, 1819 (Pulmonata: Arionidae)

Harmful land snails and slugs are currently one of the most important threats facing agriculture in many parts of the world. Synthetic molluscicides are the main control method against these gastropods. However, dangers caused by these chemicals to the environment have led scientists to research for environmentally friendly alternatives. The objective of our work was to test and evaluate food pellets containing roots, stems, leaves or flowers of Euphorbia helioscopia against Theba pisana and Arion hortensis adults. Toxicity of the prepared pellets varied depending on plant organ and mollusc species tested. Pellets made of stems (LD50 = 1.35 g / 100 ml of agar at 2%) and leaves (LD50 = 1.39 g / 100 ml of 2% agar) proved more toxic to adult snails than those made of roots and flowers, which had no significant effects. In the case of slugs, pellets made of leaves (LD50 = 1.14 g / 100 ml of 2% agar) were more toxic than those made of stems (LD50 = 1.33 g / 100 ml of 2% agar), flowers (LD50 = 1.75 g / 100 ml of 2% agar) and roots (LD50 = 1.98 g / 100 ml of 2% agar). Compared to a synthetic product containing metaldehyde 5%, the results show that the use of these molluscicides derived from plants as pellets is environment- and healthconscious, targeted and economical. These products can be used in plant protection against phytophagous slugs and snails.

Chlorophyllin Treatment Against the Snail Lymnaea acuminata: A new tool in Fasciolosis Control

Objective: To observe the toxicity of chlorophyllin against Lymnaea acuminata to control fasciolosis caused by liver fluke fasciola gigantica, very prominent in eastern region of Uttar Pradesh. Materials and Methods: Ten snails Lymnaea acuminata were placed in a glass aquarium containing 3 L of dechlorinated tap water. These snails were treated with different concentrations of chlorophyllin. Chlorophyll was extracted from spinach with the help of macerated leaves and kept for 2 h in 100% ethanol at 55ºC. Results: The results of the experiment showed that the photodynamically active chlorophyllin, at low concentration was able to kill the snails under exposure of solar radiation in summer season instead of winter season. In winter, extracted chlorophyllin toxicity against L. acuminata in sunlight (96 h LC50 91.82 mg L-1) /laboratory condition (96 h LC50 921.93 mg L-1) was less than pure chlorophyllin in sunlight (96 h LC50 12.05 mg L-1) /laboratory condition (96 h LC5019.22 mg L-1), respectively. In summer, pure chlorophyllin was more toxic in sunlight (96 h LC50 3.90 mg L-1) than laboratory condition (96 h LC50 7.18 mg L-1). Pure chlorophyllin is more than five times toxic than synthetic molluscicides. Treatment of chlorophyllin caused no toxic effect against the fish (Colisa fasciatus). The result presented in this paper is found very beneficial and ecologically safe, as a photodynamic substance chlorophyllin, which found in every green plant. Conclusion: Phytotherapy of snails by photodynamic water soluble chlorophyllin to control fasciolosis can be used as potent molluscicides with low cost and easily biodegradable.

Development and Evaluation of Poly Herbal Molluscicidal Extracts for Control of Apple Snail (Pomacea maculata)

Golden Apple Snail (GAS) is the most destructive invasive rice pest in Southeast Asia. The cost of synthetic molluscicides, their toxicity to non-target organisms, and their persistence in the environment have propelled the research of plant-derived molluscicides. Most research efforts have focused on individual plant extracts for their molluscicidal potency against GAS and have not been proven to be entirely effective in rice field conditions. Selective combination of synergistically acting molluscicidal compounds from various plant extracts might be an effective alternative. In this direction, ethanolic extracts from six different plants (Neem, Tobacco, Nerium, Pongamia, Zinger, and Piper) were evaluated against Pomacea maculata Perry. Of the various combinations studied, a binary extract (1:1) of nerium and tobacco (LC90 177.71 mg/L, 48 h), and two tri-herbal extract formulations (1:1:1) of (nerium + tobacco + piper) and (nerium + tobacco + neem) were found to be most effective, with LC90 values of 180.35 mg/L and 191.52 mg/L, respectively, in laboratory conditions. The synergistic effect of combined herbal extracts resulted in significant reduction in LC90 values of the individual extracts. The findings of this study demonstrate that the selective combinations of potent molluscicidal herbal extracts are effective for management of P. maculata under laboratory conditions.

English

Schistosomiasis is a widespread parasitic infection whose intermediate host is aquatic snails and affects more than 250 million people worldwide. Although control of the snails with synthetic molluscicides is possible, it is not greatly preferred due to concerns of environmental toxicity and the relatively high cost of the chemicals. Conversely, organic plant-derived molluscicides are a better alternative that can be used to reduce the incidence of the disease. The objective of this study was to evaluate the molluscicidal activity of the plants Phytolacca octandra, P. dodecandra and Balanites aegypiaca. The major parts of the whole plant (berries, leaves, stems and roots) were collected, air dried to constant weight, macerated to a fine powder and extracted separately using methanol in soxhlet apparatus. The extracts were screened for activity using brine shrimp lethality test and thereafter tested for molluscicidal activity. There was no significant difference observed in the activity of the plant parts studied and of the three plant species in the brine shrimp lethality test. Similarly, no significant difference in molluscicidal activity of the plant parts studied and in the three plants against bulinus snails was detected. It was concluded that that the three plants can be used in the control of schistosomiasis transmitting snails. Key words: Schistosomiasis, molluscicidal, Bulinus snails, brine shrimp, Phytolacca octandra, Phytolacca dodecandra, Balanites aegypiaca