Molluscicidal activity of Sapindus mukorossi and Terminalia chebula against the freshwater snail Lymnaea acuminata

The molluscicidal activity of Sapindus mukorossi and Terminalia chebula fruit powder against the vector snail Lymnaea acuminata was time and concentration dependent. The molluscicidal activity of T. chebula fruit powder (96 h LC(50):93.59 mg L(-1)) was more pronounced than that of S. mukorossi fruit powder (96 h LC(50):119.57 mg L(-1)). Ethanolic extracts of S. mukorossi and T. chebula fruit powder were more toxic than their other organic solvent extracts. The molluscicidal activity of ethanolic extract of S. mukorossi fruit powder (24h LC(50):2.75 mg L(-1)) was more effective than the ethanolic extract of T. chebula fruit powder (24h LC(50):124.06 mg L(-1)). The 96 h LC(50) of column-purified fraction of S. mukorossi fruit powder was 5.43 mg L(-1) whereas those of T. chebula fruit powder was 7.49 mg L(-1). Column, thin layer and high performance liquid chromatography analysis demonstrates that the active molluscicidal component in S. mukorossi and T. chebula is saponin (96 h LC(50):1.31 mg L(-1)) and tannic acid (96 h LC(50):1.64 mg L(-1)), respectively. These plants may be used as potent source of molluscicides against the snail L. acuminata.     

Molluscicidal activity of Ferula asafoetida, Syzygium aromaticum and Carum carvi and their active components against the snail Lymnaea acuminata

The molluscicidal activity of dried root latex powder of Ferula asafoetida, flower-bud powder of Syzygium aromaticum and seed powder of Carum carvi against the snail Lymnaea acuminata was studied. The molluscicidal activity of all the three plant products was found to be both time and concentration dependent. The toxicity of S. aromaticum flower-bud powder (96 h LC(50):51.98 mg/l) was more pronounced than that of root latex powder of F. asafoetida (96 h LC(50):82.71 mg/l) and seed powder of C. carvi (96 h LC(50):140.58 mg/l). Ethanol extract was more toxic than other organic extracts. The ethanol extract of S. aromaticum (24h LC(50):83.53 mg/l) was more effective than that of F. asafoetida (24h LC(50):132.31 mg/l) and C. carvi (24h LC(50):130.61 mg/l) in killing the test animals. The 96 h LC(50) of column purified fraction of seed powder of C. carvi was 5.40 mg/l whereas those of flower-bud powder of S. aromaticum and dried root latex powder of F. asafoetida were 7.87 and 9.67 mg/l, respectively. The product of F. asafoetida, S. aromaticum and C. carvi may be used as potent molluscicides.     

Bioaccumulation of aluminium in the freshwater snail Lymnaea stagnalis at neutral pH

This study examined the accumulation of aluminium (Al) by the freshwater snail Lymnaea stagnalis at neutral pH, when most Al would be predicted to be in an insoluble form (Al(OH)(3)). Snails were exposed to a range of Al concentrations (38-285 microg l(-1)) for 30 days, followed by 20 days in clean water. Aluminium was measured using atomic absorption spectroscopy. Significant accumulation of Al occurred in the whole soft tissues, gut, digestive gland and kidney at the latest by day 10. High concentration factors were observed, ranging from 4.5 x 10(3) in the whole soft tissues to 6.3 x 10(4) in the kidney, corresponding to actual concentrations of 800 to 7500 microg g(-1), respectively. Proportionality between environmental (water) and tissue concentrations of Al was observed in the gut but not in the other tissues. Following transfer to clean water, rapid loss of Al from the whole soft tissues and gut was seen over the first 10 days. Loss of Al from the digestive gland was much less as a proportion of the total, with approximately 90% of the Al remaining in the tissue. In contrast, significant loss of Al from the kidney occurred between days 20 and 30, even in the continued presence of Al; little further loss occurred following transfer to clean water. Aluminium is clearly available to the snail at neutral pH, the most likely route of entry being the gut. This could facilitate entry of the metal into the food chain. The possible roles of the digestive gland and kidney in the handling of Al are discussed.     

Inhibition kinetics of certain enzymes in the nervous tissue of vector snail Lymnaea acuminata by active molluscicidal components of Sapindus mukorossi and Terminalia chebula

Effect of active molluscicidal components of Sapindus mukorossi and Terminalia chebula on the acetylcholinesterase (AChE), acid and alkaline phosphatase (ACP/ALP) activity in the nervous tissue of freshwater snail Lymnaea acuminata were studied. In vivo and in vitro exposure of saponin (active component of S. mukorossi pericarp) and tannic acid (active component of T. chebula) significantly inhibited the AChE, ACP and ALP activity in the nervous tissue of L. acuminata. The inhibition kinetics of these enzymes indicate that saponin and tannic acid caused competitive and competitive-non-competitive inhibition of AChE, respectively. Saponin also caused competitive and competitive-non-competitive inhibition of ACP and ALP, respectively, whereas tannic acid caused competitive-non-competitive inhibition of ACP and ALP. Thus the inhibition of AChE, ACP and ALP by saponin and tannic acid in the nervous tissue of L. acuminata may be the cause of molluscicidal activity of S. mukorossi and T. chebula.     

Role of ROS generation in acute genotoxicity of azoxystrobin fungicide on freshwater snail Lymnaea luteola L

Environmental Science and Pollution Research - Azoxystrobin (AZ) is an aryloxy pyrimidine fungicide extensively applied in the agriculture field all over the world. There is a little information...     

Chronic toxicity of tributyltin to development and reproduction of the European freshwater snail Lymnaea stagnalis (L.)

Chronic toxicity, growth and reproduction were measured in the freshwater gastropod Lymnaea stagnalis exposed to waterborne bis(tri-n-butyltin) oxide (TBTO) over a range of four nominal concentrations (0-10microg TBTl(-1)). Egg development was completely inhibited at 10microg TBTl(-1), whilst abnormal embryonic development was observed at 1microg TBTl(-1). For the solvent control and the 0.01microg TBTl(-1)treatment group, normal development of L. stagnalis was observed. Survivorship of hatchlings was significantly reduced by TBT at 1microgl(-1) while inhibition of shell growth of L. stagnalis was also observed at this concentration. The data were used to determine intrinsic growth rates (r) using two theoretical approaches (the Euler-Lotka equation and a Leslie Matrix). Both approaches showed that survival, fecundity and population growth rate were reduced at 1microg TBTl(-1). Interestingly, at 0.01microg TBTl(-1) snails showed a higher fecundity and growth rate than in the solvent control. The TBT concentration at which the r would equal zero (ECr(0)) and the population NOEC (No Observed Effect Concentration) were estimated. The population NOEC was defined as either the lower 95% confidence or lower 95% pointwise percentile limit of the ECr(0). Values obtained using the two different approaches were similar and thus a geometric mean was calculated to obtain a final representative population NOEC value for L. stagnalis of 2745ng TBTl(-1). The present data together with chronic toxicity TBT data for freshwater organisms, obtained from peer-reviewed literature, were used to construct a species sensitivity distribution (SSD). A predicted no effect concentration was then derived from the SSD (hazardous concentration at 5%, i.e., HC5 or 95% protection level). This SSD was compared with the SSD derived from saltwater species datasets. The HC5 value for saltwater species (3.55ng TBTl(-1); lower confidence limit: 1.93ng TBTl(-1)) was significantly lower than that for freshwater species (30.13ng TBTl(-1); lower confidence limit: 9.23ng TBTl(-1)), indicating that saltwater species are probably more susceptible to TBT than their freshwater counterparts.     

Effect of binary combination of deltamethrin+MGK-264 on the levels of phospholipid and lipid peroxidation in the snail Lymnaea acuminata

Effect of sublethal treatment of (40% and 60% of 48 h LC50) of deltamethrin+MGK on phospholipid level and rate of lipid peroxidation in nervous and foot tissue of Lymnaea acuminata were studied. Maximum reduction in phospholipid (24.10%) level and increase in rate of lipid peroxidation (586.8%) were observed in foot tissue of snail exposed to 60% of 48 h LC50 of deltamethrin+MGK 264 for 96 h. Alterations in the levels of phospholipids and rate of lipid peroxidation were time and concentration dependent. Use of MGK-264 with deltamethrin increases the toxicity of deltamethrin and their action on membrane phospholipids and rate of lipid peroxidation.     

Combinations of Azadirachta indica and Cedrus deodara oil with piperonyl butoxide, MGK-264 and Embelia ribes against Lymnaea acuminata

The binary and tertiary combinations of plant-derived molluscicides Azadirachta indica and Cedrus deodara oil with synergists MGK-264, piperonyl butoxide (PB) and fruit powder of Embelia ribes were used against the Lymnaea acuminata. It was observed that the toxic effects of these mixtures were time- and dose-dependent. The binary and tertiary mixtures of plant-derived molluscicides with synergists were more toxic with respect to the single treatment of the plant-derived molluscicides. Maximum synergistic action in binary and tertiary combinations was found in A. indica + C. deodara oil and A. indica + PB + C. deodara in 1:7 and 1:5:7 ratio, respectively.     

Effects of coal-smoke pollutants from different sources on the growth, chlorophyll content, stem anatomy and cuticular traits of Euphorbia hirta L

Variations occurred in the growth, assimilate partitioning, chlorophyll content, stem anatomy and leaf cuticular traits of Euphorbia hirta L. on long-term exposure to coal-smoke pollutants prevailing at two sites, one situated close to a railway loco shed (site B) and another in the vicinity of a thermal power plant (site C). The Botanical Garden of Aligarh Muslim University, Aligarh, was considered as a control site (A). Site C possessed a greater load of coal-smoke pollutants than site B. The present study had shown that coal-smoke pollutants have led to a decrease in plant height, jeopardised the production of leaves and enhanced their fall, and caused a reduction in leaf area, leading to decreases of the total photosynthetic area of the plants, with increasing pollution load. The losses incurred in chlorophyll a were relatively more than chlorophyll b and, as a result, the total chlorophyll contents of leaves were decreased in polluted plants. The dry weights of stems, roots and leaves were decreased to different degrees, whereas the shoot/root dry weight ratio was found to increase in the polluted environment. The growth of stem cortex and pith were slightly affected on site B, but showed significant decreases on site C, due to a greater load of pollutants. Decreased area of xylem tissue was found to couple with an increasing number of vessels of reduced sizes. The stomatal density, pore size and index showed decreases, while the epidermal cells were larger and trichomes longer, on both surfaces of polluted leaves.     

Biochemical stress response in freshwater fish Channa punctatus induced by aqueous extracts of Euphorbia tirucalli plant

Piscicidal activities of aqueous extracts of Euphorbia tirucalli were very well established, but their ultimate mode of action on fish metabolism was not yet known. Exposure of fishes over 24h or 96h to sub-lethal doses (40% and 80% of LC(50)) of aqueous extract of E. tirucalli stem-bark and latex, significantly (P<0.05) altered the level of total protein, total free amino acids, nucleic acids, glycogen, pyruvate, lactate and activity of protease, alanine aminotransferase, aspartate aminotransferase, acetylcholinesterase and cytochrome oxidase enzyme in liver and muscle tissues of freshwater fish Channa punctatus. The alterations in all these biochemical parameters were significantly (P<0.05) time- and dose-dependent. After 7d of withdrawal of treatment of 80% of LC(50) of E. tirucalli extracts shows that there was a partial recovery in the levels of glycogen but nearly complete recovery in total protein, total free amino acids, pyruvate, lactate, nucleic acids level and activity of protease, aspartate aminotransferase, alanine aminotransferase, acetylcholinesterase and cytochrome oxidase enzyme in both the tissues of fish. Thus aqueous extracts of E. tirucalli adversely affect respiratory pathway of fish and cause energy crisis during stress by suppressing ATP production. The reversibility of the action of the aqueous extracts would be an additional advantage in their use.     

Effect of humic acid on water chemistry, bioavailability and toxicity of aluminium in the freshwater snail, Lymnaea stagnalis, at neutral pH

The influence of humic acid on the water chemistry of environmentally relevant concentrations of Al at neutral pH was studied, together with its effect on the bioavailability and toxicity of Al in Lymnaea stagnalis. Humic acid significantly reduced the loss of Al from the water and increased the fraction of filterable Al, although this was a relatively small fraction of total Al. Filterable Al concentration in the presence or absence of humic acid was independent of initial Al concentration. Humic acid only partly reduced toxicity, as observed by a reduction in behavioural suppression, and had no effect on the level of Al accumulated in tissues. These results suggest that humic acid maintains Al in a colloidal form that is bioavailable to L. stagnalis. However, these colloidal Al-humic acid species were less toxic since behavioural toxicity was reduced. Humic acid may play an important role in limiting the toxicity of Al to freshwater organisms.     

Toxic effect of different types of titanium dioxide nanoparticles on Ceriodaphnia dubia in a freshwater system

Environmental Science and Pollution Research - In the current study, the effect of different types of titanium dioxide (TiO2) nanoparticles (NPs) (rutile, anatase, and mixture) was analyzed on...     

Toxic effect of synthetic pyrethroid permethrin on the enzyme system of the freshwater fish Channa striatus

Treatment with 40% and 80% of the LC50 (24h) of the pyrethroid permethrin after 24h exposure causes significant reduction in the activity of lactate dehydrogenase and cytochrome oxidase and enhanced the succinate dehydrogenase activity in the tissues of the freshwater fish Channa striatus. The results indicate that permethrin blocks aerobic as well as anaerobic metabolism in the exposed fishes.     

Synergistic effect of Eugenia jambolana Linn. and Solidago canadensis Linn. leaf extracts with deltamethrin against the dengue vector Aedes aegypti Linn. at Mysore

With the goal in mind to minimize the application of environmentally hazardous chemical insecticides, the larvicidal activity of two plant extracts along with deltamethrin was studied at University of Mysore. The extracts of Solidago canadensis and Eugenia jambolana were employed for working out the synergistic efficacy against Aedes aegypti larvae, as the extracts of both the plants exhibited high efficacy when applied individually. The deltamethrin when analyzed separately, LC₅₀ and LC₉₀ values were 0.00045 and 0.00148 ppm, respectively. Synergistic studies with two plant extracts on deltamethrin revealed S. canadensis as more effective with synergistic factor(SF) of 4.090 for LC₅₀ value and 4.781 for LC₉₀ followed by E. jambolana with SF 1.80 for LC₅₀ and 2.467 for LC₉₀ at 1:1 ratio of the phytoextracts and deltamethrin. Thus, S. canadensis was found to be a better larvicidal and synergistic agent. Combination of phytochemical and insecticide were found to be more effective than insecticides or phytochemicals alone which could be a good ecofriendly and cost-effective approach to reduce the dose of chemicals with high residual effect to be applied in vector control programs.     

Role of exogenous and endogenous silicon in ameliorating behavioural responses to aluminium in a freshwater snail

Aluminium accumulation by the freshwater snail Lymnaea stagnalis is correlated with behavioural depression which is ameliorated by addition of orthosilicic acid. We hypothesised that Si is relocated to the digestive gland in response to Al, leading to the formation of non-toxic hydroxyaluminosilicates (HAS). Exposure to 500 microg l(-1) Al for 30 days was associated with an initial period of behavioural depression, followed by apparent tolerance and subsequent depression, suggesting saturation of the cellular detoxification pathway during prolonged exposure. Exogenous Si (7.77 mg l(-1)) completely ameliorated all behavioural effects of Al but did not prevent its accumulation. In the presence of added Al, significantly more of this Si was accumulated by the tissues, compared to controls and snails exposed to Si alone. In snails exposed to Al plus Si, Al and Si concentrations were significantly correlated, with a ratio around 3:1 Al:Si, consistent with the presence of the non-toxic HAS protoimogolite.     

Piscicidal effect of some common plants of India commonly used in freshwater bodies against target animals

Mortality caused by the aqueous extracts of leaf and stem bark of four plants belonging to family Euphorbiaceae and Apocynaceae against freshwater fish Channa punctatus has been reported. It was found that dilute aqueous solutions of leaf and stem bark were active in killing the fishes. The toxic effect of stem bark of all the plants were time as well as dose dependent. There was significant negative correlation between LC50 and exposure periods. Thus, the LC50 values of stem bark extracts of Euphorbia royleana, Jatropha gossypifolia, Nerium indicum and Thevelia peruviana were decreased from 0.050 g/l (24 h) > to 0.020 g/l (96 h); 4.61 g/l (24 h) > to 4.34 g/l (96 h); 0.097 g/l (24 h) > to 0.041 g/l (96 h) and 4.05 g/l (24 h) > to 3.17 g/l (96 h), respectively. It has been suggested that these plant products cannot be used directly in freshwater bodies, without their detailed studies on long-term effects on non-target organism as well their structure activity relationship.     

Chemical and microbial hypotheses explaining the effect of wastewater treatment plant discharges on the nitrifying communities in freshwater sediment

Nitrification is a microbial key step of the nitrogen cycle, which performs the oxidation of ammonium to nitrate, via nitrite. In aquatic environments, it mainly takes place in the sediment or is associated with suspended particles. Wastewater treatment plant (WTP) discharges in rivers may disrupt sediment nitrification: this impact is related to nitrogen inputs (mainly NH(4)(+) and organic nitrogen) but could also depend on the nitrifying bacteria inputs which have been proved to survive downstream WTP discharge points. The aim of the present study was to assess the effect of NH(4)(+) and nitrifying bacteria inputs on the two steps of nitrification in freshwater sediments.To avoid natural sites constraints and to control the main environmental parameters, we used microcosms to simulate a river receiving different types of WTP discharges. These microcosms were composed of five glass dual-walls reactors (6 l) containing sediment and continuously filled (controlled flow) with river water and WTP effluent. Two types of effluents were tested: a non-nitrified one (high NH(4)(+) input, very few nitrifying bacteria) and a nitrified one (low NH(4)(+) input, more nitrifying bacteria), at different effluent/freshwater ratios (0/100, 20/80, 40/60 and 80/20). Changes in the ammonium- and nitrite-oxidizing communities were assessed by the Most Probable Number method, and changes in potential ammonium-oxidizing activity and potential nitrite-oxidizing activity were determined by incubations with specific inhibitors (sodium chlorate and allylthiourea).In most of the cases the presence of effluent induced significant changes of the nitrifying bacteria densities and potential activities in the sediment. This effect indicates generally a loss of specific potential activity and in most of the time is significant for a high effluent/river water ratio (40% to 80%). In our experimental conditions and in the case of a large WTP discharge, the nitrifying potential in freshwater sediments could thus be significantly modified.     

Effects of environmental concentrations of atrazine on hemocyte density and phagocytic activity in the pond snail Lymnaea stagnalis (Gastropoda, Pulmonata)

Immunotoxicological effects of environmentally relevant concentrations (10, 23, 50, 100 microg/l) of atrazine were studied in Lymnaea stagnalis. Individual hemolymph sampling was performed at 0, 24, 48, 72, 96, 168, 336, 504 and 672 h during exposure. Every atrazine concentration induced a significant increase in the mean number of circulating hemocytes, without any concentration-response relation. A peak (1.6-fold increase) of hemocyte density was observed after 96 h of exposure. After 504 h, the number of hemocytes remained higher only in the snails exposed to the two highest concentrations. Granulocytes contributed most to the increase in hemocyte density in herbicide-exposed snails. Both short- (24 and 96 h) and long-term (504 h) exposures resulted in significant inhibition of hemocyte phagocytic activity upon E. coli. Over the long-term, phagocytosis recovered for the two lowest concentrations. After 504 h of exposure, every herbicide level resulted in a significant reduction of reactive oxygen species production in E. coli-stimulated hemocytes, which was not observed for short-term exposures.     

Environmental transformation of triadimefon in water and on plant leaf surface

Phototransformation of triadimefon was studied in aqueous solution and on plant leaf surface under natural and simulated conditions. Photoproducts such as 4-chlorophenol, 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1,2,4-triazole-1-yl)-butan-2-ol and 1-phenoxy-3,3-dimethyl-but-2-one were identified on leaf as well as in aqueous solution. A new photoproduct product 1-(4-chlorophenoxymethyl)-1,2,4-triazole was identified only on the leaf surface. The rate of degradation was more in tap water as compared to rain and distilled water.     

Progestogen-induced alterations and their ecological relevance in different embryonic and adult behaviours of an invertebrate model species,the great pond snail (Lymnaea stagnalis)

Environmental Science and Pollution Research - The presence of oral contraceptives (basically applying estrogens and/or progestogens) poses a challenge to animals living in aquatic ecosystems and...