Improvement of Heliciculture by Three Medicinal Plants Belonging to the Lamiaceae Family.

Snails were fed with three medicinal plants belonging to the Lamiaceae family (rosemary, sage, and peppermint) in order to test their effects on those animals with high nutritive values. The media of raising were flour containing different percentages of the cited plants ranging from 1% to 9%. The feed had benefits on the raised snails depending on the plant and its percentage. Minerals in those aromatic plants, especially zinc and magnesium, had their effect on protein synthesis in snails fed with those plant percentages. Rosemary was the most profitable plant with the highest protein amount, the lowest mortality rate, and reduced microbial charge. Furthermore, it was a good regulator of the specific catalase activity which confirmed the role of the antioxidant activity of rosemary during raising snails.

A Pilot Evaluation of the Toxicity of EarthTec® QZ on Invasive (Bithynia tentaculata) and Native (Physa gyrina) Snail Species from the Upper Mississippi River.

We used a comparative approach to investigate the effects of a copper-based pesticide (EarthTec® QZ) on embryos of an invasive snail (Bithynia tentaculata) and a native snail (Physa gyrina). Embryos were exposed to one of three treatments: control (0 mg/L Cu2+), low-dose (0.1 mg/L Cu2+), or high-dose (0.6 mg/L Cu2+), which reflect manufacturer-recommended low and medium 4-day molluscicide treatment concentrations. Exposure to 0.6 mg/L Cu2+ over 4 days generated 100% mortality in both invasive and native snail embryos; however, reducing the exposure time from 4 to 1 day resulted in 100% mortality in B. tentaculata but some hatching (7%) in P. gyrina. In contrast, embryos of both species exposed to 0.1 mg/L Cu2+ treatment for 4 days showed almost 100% survivorship. Further manipulations of Cu2+ concentrations and exposure times may yield regimes that maximize mortality in B. tentaculata while minimizing negative impacts on native species.

A new method for laboratory rearing of Galba truncatula, the intermediate host of Fasciola hepatica.

In this study a relatively large and open top aquarium was designed, constructed and introduced as a suitable habitat for nutrition, growth and development as well as for egg laying and breeding of Galba truncatula under laboratory conditions. The soil and water used in the aquarium were collected from the locality in which the snails were collected. The aquarium was placed in a laboratory with temperature of 18-32 ºC and relative humidity of 22-37% respectively, according to the season. The artificial light was controlled by a light timer, giving 12 h of light and 12 h of darkness. The snails were fed with dried lettuce leaves, Cyperus alternifolius (aquatic plant), Spirulina (algae), Orthotrichum rupestre (moss) and cuttlebone (a supplementary source of calcium). Approximately five weeks after the start of study, there was evidence of reproduction and success in rearing of G. truncatula by the appearance of eggs and small snails (0.1-0.5 mm) in the aquarium. In conclusion, large scale laboratory rearing of G. truncatula is a feasible task. The method may be improved by balancing the temperature and relative humidity as well as by optimizing the soil type, the water quality and the type of food.

Effects of the herbicide surfactant MON 0818 on oviposition and viability of eggs of the ramshorn snail (Planorbella pilsbryi).

The surfactant mixture MON 0818 is an adjuvant in various commercial formulations of the herbicide glyphosate. Initial studies have shown that MON 0818 is more toxic to aquatic animals than the active ingredient. However, few studies have examined the effect of exposure to MON 0818 on species of mollusks, and no studies have examined the effect on gastropods. The present study investigated the effect of acute exposure (96 h) of MON 0818 to the eggs, juveniles, and adults of the file ramshorn snail (Planorbella pilsbryi). Concentrations of MON 0818 up to 9.9 mg/L did not have a significant effect on the viability of eggs (p > 0.05). Juvenile snails (50% lethal concentration [LC50] = 4.0 mg/L) were more sensitive than adult snails (LC50 = 4.9-9.1 mg/L). Oviposition was inhibited by exposure to MON 0818 (median effective concentration [EC50] = 0.4-2.0 mg/L). However, oviposition resumed when snails were removed to clean water, even after 96-h exposure to up to 4.9 mg/L of MON 0818. Exposure to a concentration ≥2.7 mg/L caused visible damage to the tentacles of adult snails, which could potentially impact chemoreception. A deterministic hazard assessment indicated that environmentally relevant concentrations of MON 0818 could pose a hazard to the deposition of eggs. However, because of the relatively short half-life of MON 0818 in aquatic systems and the ability of snails to resume oviposition following the dissipation of MON 0818, environmentally relevant concentrations of MON 0818 likely pose a de minimis risk to populations of ramshorn snails. Environ Toxicol Chem 2017;36:522-531. © 2016 SETAC.

Reciprocal transplant reveals trade-off of resource quality and predation risk in the field.

Balancing trade-offs between avoiding predators and acquiring food enables animals to maximize fitness. Quantifying their relative contribution to vital rates in nature is challenging because predator abundance and nutrient enrichment are often confounded. We employed a reciprocal transplant study design to separate these confounded effects on growth and reproduction of snails at wetland sites along a gradient of predator threats and phosphorus (P) enrichment associated with a canal. We held snails in mesh bags that allowed the passage of waterborne predator cues and fed them local or transplanted periphyton. Molluscivores were more abundant near the canal, and snails tethered near the canal suffered 33% greater mortality than those tethered far from it (far sites). The greatest difference in snail growth rates was at the far sites where growth on far periphyton was 48% slower than on P-enriched (near canal) periphyton. Close proximity to the canal reduced growth on near periphyton by 21% compared to growth on the same periphyton far from the canal; there was no difference in growth rate on either periphyton type when snails were raised near the canal. Snails laid 81% more egg masses at far sites than at near sites, regardless of periphyton origin. Top-down and bottom-up processes were elevated near the canal, and their effects canceled on growth, but not reproduction. Phenotypic trade-offs such as these may explain why some taxa show little response to nutrient enrichment, compared to others, or that the effects of nutrient enrichment may be context dependent.

A benzoic acid derivative and flavokawains from Piper species as schistosomiasis vector controls.

The search of alternative compounds to control tropical diseases such as schistosomiasis has pointed to secondary metabolites derived from natural sources. Piper species are candidates in strategies to control the transmission of schistosomiasis due to their production of molluscicidal compounds. A new benzoic acid derivative and three flavokawains from Piper diospyrifolium, P. cumanense and P. gaudichaudianum displayed significant activities against Biomphalaria glabrata snails. Additionally, "in silico" studies were performed using docking assays and Molecular Interaction Fields to evaluate the physical-chemical differences among the compounds in order to characterize the observed activities of the test compounds against Biomphalaria glabrata snails.

Response to phosphorus limitation varies among lake populations of the freshwater snail Potamopyrgus antipodarum.

Local adaptation--typically recognized as higher values of fitness-related traits for native vs. non-native individuals when measured in the native environment--is common in natural populations because of pervasive spatial variation in the intensity and type of natural selection. Although local adaptation has been primarily studied in the context of biotic interactions, widespread variation in abiotic characteristics of environments suggests that local adaptation in response to abiotic factors should also be common. Potamopyrgus antipodarum, a freshwater New Zealand snail that is an important model system for invasion biology and the maintenance of sexual reproduction, exhibits local adaptation to parasites and rate of water flow. As an initial step to determining whether P. antipodarum are also locally adapted to phosphorus availability, we examined whether populations differ in their responses to phosphorus limitation. We found that field-collected juvenile P. antipodarum grew at a lower rate and reached an important size threshold more slowly when fed a relatively low vs. a relatively high-phosphorus diet. We also detected significant across-population variation in individual growth rate. A marginally significant population-by-dietary phosphorus interaction along with a two-fold difference across populations in the extent of suppression of growth by low phosphorus suggests that populations of P. antipodarum may differ in their response to phosphorus limitation. Local adaptation may explain this variation, with the implication that snails from lakes with relatively low phosphorus availability should be less severely affected by phosphorus limitation than snails from lakes with higher phosphorus availability.

[Mollusicidal effects of some species of plants in hilly and mountainous areas].

OBJECTIVE: To valuate the mollusicidal effects of some plants cultivated in the hilly and mountainous areas on Oncomelania hupensis and screen the plants against O. hupensis snails. METHODS: The mollusicidal effects of water extracts of plant materials were tested in laboratory. RESULT: The LC50 of all the species in 24 h, 48 h, and 120 h reached the middle noxious level against O. hupensis snails. According to the taxis of LC50(s) in 120 h, Eucalyptus camaldulensis was best with a LC50 of 0.013%, and Ailanthus altissima, Zanthoxylum bungeanum, Juglans regia, Melia azedarach, Nerium indicum, Pterocarva stenobtera, Cinnamomum camphora, Vetiveria zizanioides, and Citrus reticulata were the second with LC50 (s) between 0.020% and 0.370%, and Zingiber officinale had a lower effect on snail control with a LC50 of above 0.500%. There was a correlation between the death rate of snails and soak time. CONCLUSION: The resources of snail-restrained plants are very abundant, and four plants, such as Eucalyptus camaldulensis, Ailanthus altissima, Cinnamomum camphora, and Vetiveria zizanioides have some mollusicidal effect.

Sensitivity to phosphorus limitation increases with ploidy level in a New Zealand snail.

Evolutionary and ecological factors that explain natural variation in ploidy level remain poorly understood. One intriguing possibility is that nutrient costs associated with higher per-cell nucleic acid content could differentially influence the fitness of different ploidy levels. Here, we test this hypothesis by determining whether access to phosphorus (P), a main component of nucleic acids, differentially affects growth rate in asexual freshwater snails (Potamopyrgus antipodarum) that differ in ploidy. As expected if larger genomes generate higher dietary P requirements, tetraploid P. antipodarum experienced a more than twofold greater reduction in growth rate in low-P versus high-P conditions relative to triploids. Mirroring these results, tetraploid P. antipodarum also had a significant reduction in body P content under low P relative to high P, whereas triploid body P content was unaffected. Taken together, these results set the stage for the possibility that P availability could influence the distribution and relative frequency of P. antipodarum of different ploidy levels. These findings could be applicable to many other animal taxa featuring ploidy-level variation, which includes many mixed sexual/asexual taxa.

[Preliminary study on molluscicidal effect of Euphorbia helioscopia L ethanol extracts against Oncomelania hupensis].

OBJECTIVE: To study the influences of Euphorbia helioscopia L. on glycogen contents of Oncomelania hupensis so as to explore its molluscicidal mechanism. METHODS: The different polar factions of Euphorbia helioscopia L. were separated by using the systemic solvent segregation method, and then its molluscicidal activity was detected according to the Laboratory Final Milluscicides Screening Method issued by WHO. The glycogen contents of soft tissues of Oncomelania hupensis snails treated by Euphorbia helioscopia L. ethanol extracts were determined by the anthrone method. RESULTS: After being immersed for 48 h with Euphorbia helioscopia L. ethanol extracts, the death rates of the snails at the concentrations of 400 mg/L and 800 mg/L were 50.43% and 77.50% respectively, while after 96 h, the death rates at the above concentrations were both 100%. The glycogen contents of the snails gradually reduced with the increase of the drug concentrations, the glycogen content decreased to the lowest while the concentration was 800 mg/L, and the glycogen content decreased by 69.49% compared with that of the control group. CONCLUSION: The Euphorbia helioscopia L. ethanol extracts can significantly decrease the glycogen content of Oncomelania snails and the extracts have an adequate molluscicidal activity.

[Preliminary screening tests of molluscicidal effect of extracts from Eucalyptus leaves].

OBJECTIVE: To investigate the molluscicidal effects of extracts from five Eucalyptus leaves collected from Guangdong Province, China. METHODS: According to the WHO recommended indoor immersed method, the molluscicidal effects of extracts from five Eucalyptus leaves with 250, 100, 10 mg/L of water extraction, alcohol precipitation and organic solvent extraction were investigated. RESULTS: The dose-effect relationship showed that all the mortality rates of Oncomelania hupensis reached 80% with the volatile oil from five Eucalyptus leaves immersed at the concentrations of 100 mg/L for 48 h, and the mortality rates were both 93.3% with the volatile oil from Corymbia citriodora and Eucalyptus urophylla leaves. The mortality rate was up to 95% with the chloroform extract, and the mortality rate reached 60% at the concentrations of 10 mg/L for 48 h. CONCLUSION: The volatile oils from five Eucalyptus leaves and the chloroform extract in alcohol extraction from Eucalyptus urophylla leaves are better than other solvents.

[Molluscicidal effect of Phytolacca americana linn leaf against Oncomelania hupensis and its acute toxicity].

OBJECTIVE: To study the molluscicidal activity, the influence on glycogen content of Oncomelania hupensis and the acute toxicity to zebra fish of the extract from Phytolacca americana Linn leaf. METHODS: The different polar factions of the extract of Phytolacca americana Linn leaf were separated by using the systemic solvent segregation method, and then the molluscicidal activity of the fractions was detected according to the Laboratory Final Milluscicides Screening Method issued by WHO. The glycogen content of soft tissues of Oncomelania hupensis treated by the ethyl acetate polar fraction was determined by the anthrone method. Finally, the acute toxicity of the ethyl acetate polar fraction to non-targets was studied with zebra fish. RESULTS: The ethyl acetate polar fraction was the best active components against the snails. Its 48 h LC50 and LC90 were 6.0 mg/100 ml and 26.1 mg/ 100 ml, respectively. The glycogen content of soft tissues of the snails decreased by 20% after treated with the fraction. The fish treated by the concentration of LC50 (48 h) of the ethyl acetate polar fraction survived for 12 h. CONCLUSION: The Phytolacca americana Linn leaf possesses an adequate molluscicidal activity and a significant acute toxicity to the zebra fish.

Phosphorus-mediated changes in life history traits of the invasive New Zealand mudsnail (Potamopyrgus antipodarum).

Understanding the mechanisms that species use to succeed in new environments is vital to predicting the extent of invasive species impacts. Food quality is potentially important because it can affect population dynamics by affecting life history traits. The New Zealand mudsnail, Potamopyrgus antipodarum, is a worldwide invader. We examined how mudsnail growth rate and fecundity responded to the C:P ratio of algal food in laboratory conditions. Mudsnails fed low-P algae (C:P 1,119) grew more slowly, matured later, produced smaller offspring, and grew to a smaller adult size than snails reared on algae with high levels of P. A relatively small increase in algal C:P (203-270) significantly increased mudsnail age at maturity. We suggest that the relatively high body P requirements of mudsnails make them susceptible to allocation trade-offs between growth and reproduction under P-limited conditions. The elemental composition of algae varies greatly in nature, and over half of the rock biofilms in streams surveyed within the introduced range of mudsnails in the Greater Yellowstone Area had C:P ratios above which could potentially pose P limitation of life history traits. High growth rate and fecundity are common traits of many species that become invasive and are also associated with high-P demands. Therefore, fast-growing consumers with high P demands, such as mudsnails, are potentially more sensitive to P limitation suggesting that limitation of growth and reproduction by food quality is an important factor in understanding the resource demands of invasive species.

Molluscicidal activity of Piper cubeba Linn., Piper longum Linn. and Tribulus terrestris Linn. and their combinations against snail Indoplanorbis exustus Desh.

The toxic effect of dried berries powder of P. cubeba, dried fruit powder of P. longum and T. terrestris singly as well as in combination [binary (1:1) and tertiary (1:1:1)] were studied against snail L. exustus. Toxicity of these plant products were time and concentration dependent. Ethanol extracts of these plants were more effective than that of other organic solvents. 96 h LC50 value of column purified fraction of T. terrestris against I. exustus was 9.57 mg/l, where as 96 h LC50 values of column purified fractions of P. longum and P. cubeba were 11.57 mg/l and 10.93 mg/l, respectively. Binary (1:1) combination of P. cubeba (PC) + P. longum (PL) (41.78 mg/l) was more effective than P. cubeba (PC) + T. terrestris (TT) (42.17 mg/l) and P. longum (PL) + T. terrestris (TT) (55.84 mg/l) respectively; while tertiary (1:1:1) combinations of P. cubeba (PC) + T. terrestris (TT) + T. foenum-graecum (TF) (10.67 mg/l) was more effective than rest of the combinations. These plants can be used as potent source of molluscicides against the snail I. exustus.

Molluscicidal saponins from leaves of Hedera canariensis.

Activity-guided fractionation of the methanol extract of Hedera canariensis (var. Gloire de Maringo) Wild leaves afforded five saponins 1-5. Chemical and spectral methods (MS, 1HNMR, 13CNMR) showed that they are glycosides of hederagenin and oleanolic acid. The results showed that 4,5 exhibited molluscicidal properties, compound 1 was inactive. Mortality rate of exposed snails increased by increasing plant extract concentration. Lymnaea cailliaudi was more sensitive to plant extract than Biomphalaria alexandrina. The histopathological study revealed distinct damage in the structure of the stomach and ovotestis of treated L. cailliaudi snails. Saponin content was determined in term of haemolytic index.

Effect of three dormant oils on schistosomiasis and fascioliasis vector snails and its relation with some non-target snails.

Three oils were tested for their molluscicidal activity, Caple-2, Kemasol and Super-max. Super-max had the strongest toxic effect on B. alexandrina and other snail species. Its LC50 was 0.53 ppm, meanwhile LC50 of Kemasol 3.2 ppm and 4.21 ppm for Caple 2. The LC50 & LC90 of the oils were lower in Lymneae natalensis as compared to B. alexandrina. The LC50 & LC90 of the oils against non-target snails (Physa acuta, Helisoma duryi, Planorbis planorbis and Melanoides tuberculata) were higher as compared to B. alexandrina. Hatchability of snails' eggs exposed to Super-max (3.0 & 5.0 ppm) was stopped completely and l.0 ppm showed the lower percent of egg hatchability 22.7 %. Caple 2 and Kemasol did not affect eggs hatchability. Supermax had the strongest harmful effect on both miracidia and cercariae of S. mansoni. 100% mortality values were obtained for both larval stages after 8 & 9 minutes respectively when maintained at LC50. 100% mortality of miracidia occurred after 35 & 155 minutes when maintained at LC50 of Kemasol & Caple 2 respectively. The infection rate of B. alexandrina with S. mansoni miracidia was greatly reduced by the sublethal concentrations of the oils. The reduction of infection rate was higher in snails treated with Supermax (42.9%). A highly significant reduction of total cercarial production per snail was in the experimental groups as compared with controls. The prepatent period of treated snails was prolonged compared to control. Moreover, Total protein content and enzyme activities of snails treated with LC10 of oils showed a significant reduction as compared with control in haemolymyph. There was an increase of protein contents in the tissue. AlkP enzyme activity was slightly increased in haemolymph of experimental groups than controls and was significantly higher in the tissues as compared to control. ALT enzyme activity in haemolymph of experimental groups was higher than control, but lower in tissue. AST enzyme activity was higher in haemolymph and tissue of experimental groups than controls. The SDS-PAGE pattern of tissue soluble proteins extracted from treated B. alexandrina and controls showed different oils effects on the synthesis of protein within snails yielded a complex pattern of polypeptides ranging in molecular weight between 13.775 to 156.7 kDa. Many bands were present in treated snails. At least, one band was detected for snails treated with each of the oils and not in controls. The difference in the similarity indices between treatment and control; for Kemasol was 0.86 & 0.64, for Caple 2 was 0.61 & 0.55 and for Supermax was 0.64 & 0.86. LC25 of Supermax did not cause any mortality to Daphnia after 6 hr. But, LC50 & LC90 caused lower mortality after 6 hr. Kemasol caused 100% mortality after 4 hr at LC50 and 2 hr in LC90. Caple 2 caused 50% mortality of Daphnia after 5 hr at LC25 &100% mortality after 30 minutes in LC50 & LC90.

Molluscicidal effect of three monoterpenes oils on schistosomiasis and fascioliasis vector snails in Egypt.

Thymol, Linalool and Eugenol showed considerable molluscicidal effect against Biomphalaria alexandrina, Bulinus truncatus and Lymnneae natalensis. The thymol was the potent one at least LC50 and LC90) followed by euganol then linalool. L. natalensis were more sensitive to these compounds followed by B. truncatus and then B. alexandrina. The LC50 & LC90) of thymol were 22 and 34 ppm against B. alexaldrina, 20 and 30 ppm for B. truncatuts and 18 and 29 ppm for L. nalalensis. These values were higher with Eugenol, 28 and 48 ppm for B. alexuadrina, 24 and 44 ppm for B. truncatus and 22 and 40 ppm for L. natalensis. Linalool showed highest values of LCs5 and LC90 against B. alexandrina, 34 and 56 ppm, against B. truncatus 30 and 52 ppm and for L. natalensis 28 and 48 ppm, respectively. Maintaining of B. alexandrina at LC10 of Thymol for one week induced an inhibitory effect in the level of some enzymes (AchE, SDH). It led to increase in the activity of other enzymes (ACP, ALP & G-6-PD). Acetylcholine-sterase activity (AchE) of treated B. alexandrina was significantly reduced by 45.9% when compared to control. The results showed a significant decrease in succinate dehydrogenase activity (SDH) by 46.4% together with a concomitant increase in glucose-6-phosphate dehydrogenase activity level (G-6-PD) by 47.5% in comparison with control. The activities of acid phosphatase and alkaline phosphatase enzymes were found to be higher in the treated snails than in control ones. The percentage increases were 47.2% & 73.2% respectively. The results also showed an elevation in the hemolymph glucose content of treated snails by 51.9% while the tissue glycogen content was reduced by 48.1%. The infection of B. alexandrina with S. mansoni miracidia was greatly reduced by thymol LC10 (sublethal dose). The infection rate reduction was 43.1%. The treated snails' prepatent period was prolonged (34.2 +/- 3.3 days) compared to control (28.4 +/- 1.2 days). A highly significant reduction of total cercarial production per snail occurred in experimental snails as compared to control.

Impact of certain plants and synthetic molluscicides on some fresh water snails and fish.

The LC50 (78, 85 ppm) and LC90 (88, 135 ppm) of Anagalis arvensis and Calendula micrantha respectively against Biomphalaria alexandrina were higher than those of the non-target snails, Physa acuta, Planorbis planorbis, Helisoma duryi and Melanoides tuberculata. In contrast, the LC50 of Niclosamide (0.11 ppm) and Copper sulphate (CuSO4) (0.42 ppm) against B. alexandrina were lower than those of the non-target snails. The mortalities percentage among non-target snails ranged between 0.0 & 20% when sublethal concentrations of CuSO4 against B. alexandrina mixed with those of C. micrantha and between 0.0 & 40% when mixed with A. arvensis. Mortalities ranged between 0.0 & 50% when Niclosamide was mixed with each of A. arvensis and C. micrantha. A. arvensis induced 100% mortality on Oreochromis niloticus after 48 hrs exposure and after 24 hrs for Gambusia affinis. C. micrantha was non-toxic to the fish. The survival rate of O. niloticus and G. affinis after 48 hrs exposure to 0.11 ppm of Niclosamide were 83.3% & 100% respectively. These rates were 91.7% & 93.3% respectively when each of the two fish species was exposed to 0.42 ppm of CuSO4. Mixture of sub-lethal concentrations of A. arvensis against B. alexandrina and those of Niclosamide or CuSO4 at ratios 10:40 & 25:25 induced 66.6% mortalities on O. niloticus and 83.3% at 40:10. These mixtures caused 100% mortalities on G. affinis at all ratios. A. arvensis CuSO4 mixtures at 10:40 induced 83.3% & 40% mortalities on O. niloticus and G. affinis respectively and 100% mortalities on both fish species at ratios 25:25 & 40:10. A mixture of sub-lethal concentrations of C. micrantha against B. alexandrina and of Niclosamide or CuSO4 caused mortalities of O. niloticus between 0.0 & 33.3% and between 5% & 35% of G. affinis. The residue of Cu in O. niloticus were 4.69, 19.06 & 25.37 mg/1kgm fish after 24, 48 & 72 hrs exposure to LC0 of CuSO4 against B. alexandrina respectively.

[Purification of the effective component from Solanum xanthocarpum and its effect against Oncomelania snails].

OBJECTIVE: To extract and purify the active component from Solanum for Oncomelania snail control, evaluate its effect against the snails and determine its chemical structure. METHODS: Pedicel and seed were moved and the remaining part of the Solanum xanthocarpum fruit was torrefied and ground into powder. The powder was soaked into 95% ethanol and extracted. The residue was treated by ethyl acetate. 7 components were separated by methods of thin layer chromatography (TLC) and column chromatography (CCL). 4 main components were observed for the effect of snail-killing by immersion method. An alkaloid with Rf = 0. 58, named as component A, was confirmed as one of the effective components for Oncomelania snail control. The component A was further purified and received Al and A2 by proper elusion, and their effect was re-tested. The molecular weight and chemical structure of A2 were determined by MS, NMR and IR respectively. RESULTS: The death rate of Oncomelania snails was 94.2% when the concentration of component A was 2.50 mg/L1(28 C ). The flow liquid system (ethyl acetate: chloroform: methanol 11:11:35) applied was the best reagent for separating component A. The death rate of Oncomelania snails in solution of A2 (0.2 mg/L) was 100% (28 degrees C). The molecular weight of A2 was 867 with an mp 298-305 C. CONCLUSION: The effective agent (A2),one of the active components from the fruit of Solanum xanthocar pum, is alpha-solamargine which shows an excellent effect in killing Oncomelania snails.

A multibiomarker approach to environmental assessment.

Incorporation of ecologically relevant biomarkers into routine environmental management programs has been advocated as a pragmatic means of linking environmental degradation with its causes. Here, suites of biomarkers, devised to measure molecular damage, developmental abnormality and physiological impairment, were combined with chemical analysis to determine exposure to and the effects of pollution at sites within Southampton Water (UK). Test species included a filter feeder, a grazer, and an omnivore to determine the sensitivity of organisms occupying different trophic levels. Linear regression confirmed a significant association between incidence of intersex in Littorina littorea and tributyltin (TBT) concentrations (R2 = 0.954) and between PAH metabolites in Carcinus maenas urine and PAHs in sediments (R2 = 0.754). Principal component analysis revealed a gradient of detrimental impact to biota from the head to the mouth of the estuary, coincident with high sediment concentrations of heavy metals, PAHs, and biocides. Multidimensional scaling identified C. maenas as the organism most sensitive to contamination. Carboxylesterase activity, metallothionein and total haemolymph protein were the most discriminating biomarkers among sites. This holistic approach to environmental assessment is encouraged as it helps to identify the integrated impact of chemical contamination on organisms and to provide a realistic measure of environmental quality.