Toxicity Effects of N. oleander and E. terracina on M. tuberculata and B. alexandrina Snails

The molluscicidal activity of different extracts of two species belonging to many families ( Nerium oleader and Euphorbia terracina ) was evaluated against two types of snails ( Melonides tuberculata and Biomphalaria alexandrina ) in the agricultural area of Taourghaa region, Libya. The results clearly showed that (The Lc50 – Lc90 for two snails and two plants of ethanol extract between (1.26 and 2143.2 ppm ) interference to ethanol extract, also the Lc 50 and Lc 90 for two snails and two plants of acetone extract between (100 and 924.


Introduction
Human schistosomiasis is a parasitic disease caused by digenetic trematode species of the genus Schistosoma which co-habitate the venous plexuses of the mammalian viscera and transmitted by freshwater gastropod molluscs which serve as intermediate hosts (Smith et al., 1989;and Lockyer et al., 2003).In the tropics and subtropics, schistosomiasis is the second most important parasitic disease after malaria in terms of prevalence, public health and socio-Toxicity Effect of N. oleander and E. terracina on M. tuberculata and ……………… Faculty of Marine Resources, Alasmarya Islamic University, Libya.

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ISSN: 2413-5267 economic importance (James and Colley, 1995;and Steinmann et al., 2006).Biomphalaria alexandrina is a species of air-breathing freshwater snail, an aquatic pulmonate gastropodmollusk in the family Planorbidae.Biomphalaria alexandrina serves as an intermediate host for Schistosoma mansoni.Man, the definitive host, acquires infection by contact with freshwater infested with schistosoma cercariae, which actively penetrate his intact skin (El Ridi, 2002;and Fayez, 2009), and subsequently develop to the adult worms.These cercariae are released into water by infected snails, in which the parasite undergoes asexual larval multiplication.The snails in turn become infected by miracidia released from schistosome eggs which reach freshwater with human excrement (Benson, 2008;and Fayez, 2009).Melanoida stuberculata is a species of freshwater snail with an operculum, a parthenogenetic, aquatic gastropodmollusk in the family Thiaridae.The common name comes from the presence of reddish spots on the otherwise greenish-brown shell.This species has an elongate, conical shell, which is usually light brown, marked with rust-colored spots.This species is native to subtropical and tropical northern Africa and southern Asia.In Africa it present in Algeria, Burundi, The Democratic Republic of the Congo, Egypt, Eritrea, Ethiopia, Kenya, Libya, Malawi, Morocco, Mozambique, Namibia, Niger, South Africa, Sudan, Swaziland, Tanzania, Tunisia, and Zimbabwe (Benson, 2008).Melanoides tuberculatus is known to carry certain parasites which can be dangerous to humans.These snails serve as first intermediate host for parasites which include: Clonorchissinensis (Chinese liver fluke), Paragonimus westermani (Oriental lung fluke), Metagonimus, Diorchitrema formosanum, Opisthor chissinensis, Philophthalmus sp., Haplorchis sp., Centrocestus formosanus and Schistosoma sp.(Nakano et al., 2003).In addition to this species is a host for a trematode parasite which has been found to infect an endangered species of fish in Texas.There is an increased attention for the use of new molluscicides which are highly effective, rapidly biodegradable, less toxic readily available and easily applicable than synthetic molluscicides, so, plant molluscicides could be appropriate for snails, especially in developing countries (Sushma, 1998;and Osman et al., 2007).It was found that many plants are growing in Tourgha region like Lantana camara, Neriumoleader, Ricinus comminus, Euphorbia terracina, Chrozophora tinctoria and Hyoscya musalbus which have may biological activities as antimicrobial, treatment of malaria, rheumatism, and skin rashes (Abdalla et al., 2009;and Sharma et al., 2009).

Study Area
This study is conducted in Agricultural Taourghaa region at 240 km east from Tripoli and 38 km from east of Misurata city.

Preparation of Extracts
120 g of each coarsely powdered plant is macerated in 300-400 ml of methanol (95% vol.) and acetone for 24 hrs at room temperature (26-29 o C).The extract is filtered and the solvents were evaporated under reduced pressure at 40 o C. Serial dilutions were done from each extract to which snails are exposed (i.e.1000, 850, 700, 500, 300, 150 and 75 ppm).

Snail Collection and Exposure
Melanoides tuberculata and Biomphalaria alexandrina which is the intermediate host for Schistosoma mansoni.They are examined in the laboratory for patent trematode infections by being placed in glass beakers with clean water, leaves of lettuce, some stones and pump of air, then kept the laboratory for a period up to four weeks and rescreened again (at the end of this period we found that the diameter of snails increased from 0.4 to1.2 cm).Only those snails free from any infection and measuring 8-10 mm in diameter are used in the laboratory experiments.
Toxicity Effect of N. oleander and E. terracina on M. tuberculata and ……………… Faculty of Marine Resources, Alasmarya Islamic University, Libya.

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ISSN: 2413-5267 10 snails of each type were placed in alcohol 50 ml volume beaker containing 50 ml of each concentration.ten snails are put in a separate beaker containing 50ml of distilled water as a control.The beakers are left in the laboratory for 24 hrs and then snails were transferred into beakers containing 50 ml of distilled water for recovery.They are examined after 24 hrs noting the dead as well as live ones.A snail is confirmed dead if it was remained immobile after having been observed for five minutes with the aid of 10 magnification hand lens and either retracted well into or hanged out of the shell, with the body and shell discoloured.
The experiments were carried out at room temperature (26-29 o C), using a mercuric thermometer.Each experiment was repeated three times.

Methods of Analysis
Probit regression analysis (by using SPSS) was carried out for all the plants tested to determine the Lc50 and Lc90 values.The slope of the regression line was used to assess the effect of the extract; the steeper the slope, the more lethal the plant molluscicide effect.

Molluscicidal Activity of Nerium Oleander:
The comparative susceptibility of the snails: Melanoides tuberculata, Biomphalaria alexandrina to the action of different extracts (ethanol, and acetone,) from N. oleander has been determined.

Ethanol Extract
The effect of various concentrations of ethanol extract of N. oleander on adults of M. tuberculata, B. alexandrina snails after 24 hrs exposure are listed in Tables (1, 3, 5, 7, 8, and 10).The results of mortality were statistically analyzed using Probit analysis.The LC50 and LC90 of this extract against M. tuberculata were 1.3 and 256.6 ppm respectively.The LC50 and LC90 of the same extract against B. alexandrina were 178.7 There was a difference between molluscicidal activities of ethanol extract of N. oleander against three tested snails.M. tuberculata were more sensitive to N. oleander extract than two other snails.

Acetone Extract
The effect of various concentrations of acetone extract of N. oleander on adults of M. tuberculata, B. alexandrina snails after 24 hrs exposure are listed in Tables (2, 4, 6, 9, 11, and 12).The results of mortality were statistically analyzed using Probit analysis.The LC50 and LC90 of this extract against M. tuberculata were 103.3 and 229.0 ppm respectively.The LC50 and LC90 of the same extract against B. alexandrina were 100 and 287.7 ppm respectively.

Molluscicidal activity of Euphorbia terracina El Serite et al., 2017
Faculty of Marine Resources, Alasmarya Islamic University, Libya.

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ISSN: 2413-5267 The comparative susceptibility of the snails: Melanoides tuberculata, Biomphalaria alexandrina to the action of different extracts (ethanol, acetone) from E. terracina has been determined.

Ethanol Extract
The effect of various concentrations of ethanol extract of E. terracina on adults of M. tuberculata, B. alexandrina snails after 24 hrs exposure are listed in Table (1).The results of mortality were statistically analyzed using Probit analysis.The Lc50 and Lc90 of this extract against M. tuberculata were 56.2 and 243.22 ppm respectively.The Lc50 and Lc90 of the same extract against B. alexandrina were 44.2 and 176.2 ppm respectively as shown in Table (3).

Acetone Extract
The effect of various concentrations of acetone extract of E. terracina on adults of M. tuberculata, B. alexandrina snails after 24 hrs exposure are listed in Table (2).The results of mortality were statistically analyzed using Probit analysis.The Lc50 and Lc90 of this extract against M. tuberculata were 311.9 and 924.7 ppm respectively.The LC50 and LC90 of the same extract against B. alexandrina were 273.5 and 857.0 ppm respectively as shown in Table (4).The molluscicidal activity of most the tested plants extracts is probably due to the presence of alkaloids, flavonoids terpenoids as well as phorble esters in E. terracina possess molluscicidal, properties (Abdel Gawad et al., 2000;Mohamed and Refahy, 2001;Refahy, 2002;and Shi et al., 2008).
In the potential molluscicides derived from local plants have attracted the attention due to high costs of imported synthetic molluscicides.Treatment of Schistosoma and Fasciloa infections remains highly problematic.In schistosomiasis, praziquantel is faced with failure to prevent reinfection as a result of development of drug resistance schistosoma strain and serious side effects, treatment of Fasciloe requires high or multiple doses of drug with frequent side effects (Refhy, 2002) These studies are usually in accordance with our study.

El
Serite et al., 2017    Faculty of Marine Resources, Alasmarya Islamic University, Libya.Whole plant materials are collected during October/November 2013, shown in Figures (1 and 2).The plants are identified at the Department of Botany, Faculty of Science, University of Tripoli.

Table 1 .
Mortality rates among M.tuberculata and B.alexandrina snails (N=10) exposed to different concentrations of alcoholic extract of Euphorbia terracina

Table 2 .
Mortality rates among M.tuberculata and B.alexandrina snails (N=10) exposed to different concentrations of acetone extract of Euphorbia terracina Toxicity Effect of N. oleander and E. terracina on M. tuberculata and ……………… Faculty of Marine Resources, Alasmarya Islamic University, Libya.

Table 3 .
Mortality rates among M. tuberculata and B. alexandrina snails (N=10) exposed to different concentrations of alcoholic extract of Nerium oleander

Table 4 .
Mortality rates among M. tuberculata and B. alexandrina snails (N=10) exposed to different concentrations of acetone extract of Nerium oleander

Table 5 .
Toxicity of the Nerium oleander alcohol extract against the snail Biomphalaria alexandrina

Table 6 .
Toxicity of the Nerium oleander acetone extract against the snail Biomphalaria alexandrina

Table 7 .
Toxicity of the Nerium oleander alcohol ext1ract against the snail Melanoides tuberculatum

Table 9 .
Toxicity of the Euphorbia terracina acetone extract against the snail Biomphalaria alexandrina

Table 10 .
Toxicity of the Euphorbia terracina alcohol extract against the snail Melanoides tuberculata

Table 11 .
Toxicity of the Nerium oleander acetone extract against the snail Melanoides tuberculata The toxicity values of ethanol extracts from different plants are arranged in a decreasing order as follows, Letium.camara Euphnorbia terracina, and the toxicity value of the acetone extracts from two plants is Nerium oleander.El Serite et al., 2017 Faculty of Marine Resources, Alasmarya Islamic University, Libya.

Table 12 .
Toxicity of the Euphorbia terracina acetone extract against the snail Melanoides tuberculata