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Simple Summary: The Asian clam, Corbicula fluminea, is a highly invasive aquatic mollusc that has become one of the most ecologically and economically harmful invasive species in aquatic ecosystems in Europe, North America, and South America. Due to the impacts of climate change, Asian clams are shifting their range farther north and are inhabiting waterbodies that were once too cold to survive. Chemical treatment has been found to be the most economical and effective management strategy for controlling invasive mollusc populations and preventing their further spread. However, chemical treatments must maximize Asian clam mortality while minimizing the impacts on water quality and non-target species. Although there are numerous treatments on the market, they are not widely applied in the field. A comprehensive review of Asian clam molluscicides was performed to evaluate the efficacy of currently available chemical treatments and the toxicity ranges of emerging treatments. The results of this review will aid resource managers in invasive Asian clam control and management. The Asian clam Corbicula fluminea is a native aquatic species in Eastern Asia and Africa but has become one of the ecologically and economically harmful invasive species in aquatic ecosystems in Europe, North America, and South America. Due to their natural characteristics as a hermaphroditic species with a high fecundity and dispersal capacity, Asian clams are extremely difficult to eradicate once they have infiltrated a waterbody. This is an emerging issue for states in the Northeastern United States, as Asian clams expand their range farther North due to climate change. There has been extensive research conducted to develop chemical treatments for reactively controlling invasive mollusc populations and proactively preventing their further spread. However, treatments are mostly targeted toward biofouling bivalves in industrial settings. A comprehensive review of Asian clam chemical treatments used in natural open-water systems was performed to evaluate molluscicides and identify the toxicity ranges of emerging treatments that maximize Asian clam mortality and minimize the negative impact on water quality and non-target species. The potential chemical applications in Asian clam control and management are summarized in this report to assist resource managers and practitioners in invasive Asian clam management. [ABSTRACT FROM AUTHOR]

Simple Summary: The invasion of the invasive alien species Pomacea canaliculata is of great concern because of its adverse influences on ecosystems, agriculture, and human health in the Asian region. Metaldehyde-containing molluscicides are often used as an effective method of controlling this species. In view of this, the present study conducted experiments to investigate the lethal concentrations of metaldehyde on Pomacea canaliculata at different exposure times. Moreover, the study also elucidated changes in enzyme activity and provided detailed histopathological evidence that shed light on the mode of action and effects of metaldehyde exposure on Pomacea canaliculata. The findings of this study not only deepen our understanding of the effects of metaldehyde on mollusks, but also provide important insights for developing better control strategies. Pomacea canaliculata, as an invasive exotic species in Asia, can adversely affect crop yields, eco-environment, and human health. Application of molluscicides containing metaldehyde is one effective method for controlling P. canaliculata. In order to investigate the effects of metaldehyde on adult snails, we conducted acute toxicological experiments to investigate the changes in enzyme activities and histopathology after 24 h and 48 h of metaldehyde action. The results showed that the median lethal concentrations (LC) of metaldehyde on P. canaliculata were 3.792, 2.195, 1.833, and 1.706 mg/L at exposure times of 24, 48, 72, and 96 h, respectively. Treatment and time significantly affected acetylcholinesterase (AChE), glutathione S-transferase (GST), and total antioxidant capacity (TAC) activity, with sex significantly affecting AChE, GST, and TAC activity and time significantly affecting carboxylesterase (CarE). In addition, the interaction of treatment and time significantly affected the activity of GST, CarE and TAC. In addition, histopathological changes occurred in the digestive glands, gills and gastropods of apple snail exposed to metaldehyde. Histological examination of the digestive glands included atrophy of the digestive cells, widening of the hemolymph gap, and an increase in basophils. In treated snails, the hemolymph gap in the gills was widely dilated, the columnar cells were disorganized or even necrotic, and the columnar muscle cells in the ventral foot were loosely arranged and the muscle fibers reduced. The findings of this study can provide some references for controlling the toxicity mechanism of invasive species. [ABSTRACT FROM AUTHOR]

Aspergillus niger is a one-of-a-kind fungus with benefits for both terrestrial and aquatic species, although research on the effects of A. niger on aquatic animal species is limited. The present study investigated the impact of Aspergillus niger, A. flavus, and Alternaria alternate filtrates on Biomphalaria alexandrina snails (the main intermediate host of Schistosoma mansoni in Egypt). Moreover, the effect of A. niger (the most toxic fungus) filtrate was assessed against infected B. alexandrina snails with S. mansoni, in addition to its efficacy against S. mansoni free larval stages. Aspergillus niger had more toxicity (100 % mortality) than A. flavus (40% mortality), while Alternaria alternate did not affect B. alexandrina snails. Chronic exposure to sub-lethal concentrations of A. niger caused histopathological changes in the head-foot, digestive gland, kidney, and hermaphrodite gland of B. alexandrina snails. Furthermore, after exposure to the determined sub-lethal concentrations of A. niger, both uninfected and infected snails with S. mansoni showed low survival rates. In addition, the lethal time for miracidia and cercariae after exposure to LC25 of A. niger was 130 and 200 minutes, respectively. Additionally, exposure to sub-lethal A niger concentrations resulted in a significant decrease in the infection rate and mean total count of cercariae shed per snail, as well as the shed of aberrant cercariae. In conclusion, Aspergillus niger filtrate had a potent molluscicidal activity against B. alexandrina, and a damaging effect on cercariae, hence it can play a role in reducing schistosomiasis. [ABSTRACT FROM AUTHOR]

Dreissenid mussels (quagga and zebra mussels, Dreissena bugensis and polymorpha) continue to spread throughout inland waterbodies of North America. Although there are considerable management and mitigation efforts underway to prevent infestation of new waterbodies, there have been relatively few successful efforts to eradicate mussels once detected due to a lack of cost-effective treatments. Two potentially cost-effective molluscicidal agents, potassium chloride (KCl, also called muriate of potash) and copper (formulated as Earthtec QZ®), have successfully treated infested waters, but have varying efficacy under different water quality and temperature conditions, and to date have only been applied in moderate conductivity waters (defined here as < 400 µS/cm) common throughout North America. Natural resource managers need information on the efficacy of these chemicals in high conductivity waters more typical of riverine systems and arid climates, in addition to the range of water temperatures typically encountered in the field. We evaluated the doseresponse of quagga mussels to KCl and Earthtec QZ® in high conductivity water (≈ 700-1,400 µS/cm) across a range of temperatures (10, 18, 22 °C) to determine appropriate doses and treatment duration resulting in 100% mortality. Our data indicate that treatments in cool temperatures (i.e., 10 °C) may be challenging for eradication efforts in high conductivity waters because none of the KCl treatments and only one copper treatment resulted in 100% mortality within the experimental period. However, both KCl (> 200 ppm) and copper (120 and 180 ppb) were consistently able to induce 100% mortality in quagga mussels in warmer temperatures (i.e., = 18 °C) and thus may be good candidates for field scale application in high conductivity waters. The results of this study indicate that field-scale application should strongly consider environmental conditions during the period of application when selecting dosages and treatment duration. [ABSTRACT FROM AUTHOR]

Objective To observe the molluscicidal effect of a new molluscicide, 10% chlorosalicylicamide (LDS), against the intermediate hosts of Schistosoma mansoni - Biomphalaria glabrata and Biomphalaria straminea, thus to provide the experimental foundation for the field application of this molluscicide. Methods The 10% LDS was formulated into the series of standard solutions with effective concentrations of 0.400 0, 0.200 0, 0.100 0, 0.050 0, 0.025 0 mg/L and 0.012 5 mg/L, respectively. B. glabrata and B. straminea were separately immersed in these solutions in the laboratory. The deaths of the above snails were observed after immersing into the solutions for 24, 48, and 72 h, and the mortalities of each group were computed, as well as the median lethal concentration LC50 (s) and relative toxicity indexes were calculated. Meanwhile, 50% wettable power of niclosamide ethanolamine salt (WPN) was set as the drug group, and dechlorinated water as the blank control group. Results The effective concentration of LDS at or above 0.100 0 mg/L, or WPN at or above 0.200 0 mg/L resulted in a 100% mortality rate for B. glabrata and B. straminea after immersing 24, 48, and 72 h. The LC50 (s) at 24, 48, and 72 hours for Biomphalaria glabrata immersed in the LDS series concentration solution was 0.047 95, 0.046 52, and 0.037 10 mg/L, respectively; while the LC50 (s) of B. glabrata in WPN serial solutions was 0.063 48, 0.057 05, 0.057 05 mg/L for 24, 48 and 72 h, respectively. For Biomphalaria straminea, the LC50 (s) at 24, 48, and 72 hours in the LDS solution was 0.012 35, 0.013 99, and 0.008 40 mg/L, respectively; and for the WPN solution, it was 0.058 95, 0.025 71, and 0.0237 5 mg/L. Using WPN as the standard drug which had higher value of LC50, and the relative toxicity index of WPN was set to 1.00, the relative toxicity indexes of LDS against B. glabrata were 1.32, 1.23 and 1.54 for 24, 48 h and 72 h, respectively, while for B. straminea, it was 4.77, 1.84, and 2.83. After 24, 48, and 72 hours of immersion in LDS, the number of surviving B. glabrata was significantly higher than that of B. straminea, with a statistical significance (χ²=8.044, 5.263, 4.658, P<0.05, respectively). Conclusions Compared to the traditional molluscicide WPN, 10% LDS shows a superior molluscicidal effect on B. glabrata and B. straminea, especially demonstrating heightened sensitivity and efficacy on B. straminea, suggesting its potential as a substitute agent for snail control. [ABSTRACT FROM AUTHOR]

A bench-scale dose-response study evaluated the efficacy of a commercially available copper-based molluscicide known as EarthTec QZ for controlling quagga veligers collected from three Southern California sites impacted by quagga mussels. A variety of concentrations were tested (0, 3, 16.7, 33.4, and 50.1 µL/L of EarthTec QZ or 0, 0.18, 1.0, 2.0, 3.0 mg/L as copper (Cu), respectively) for different durations (0.5, 2, 5, and 24 hours) on quagga mussel veligers. Water from each study site was also used in non-target 96-hour acute toxicity testing of three other species. A suite of water quality parameters was measured to characterize the differences between the study sites. The federal and California secondary maximum contaminant level and action level for copper in drinking water are 1.0 and 1.3 mg/L as Cu, respectively; therefore, results for the 16.7 µL/L EarthTec QZ (1.0 mg/L as Cu) test condition were the main reference point for assessing the efficacy of EarthTec QZ as a feasible treatment strategy. Under this condition, veliger mortality at two study sites, Lake Mathews, and a downstream water treatment plant, was found to be greater than 60% and 85% after 5 hours, and 95% and 100% after 24 hours, respectively. Lower efficacy was observed for the Lake Piru study site, with approximately 30% veliger mortality after 24 hours. Alkalinity, dissolved organic carbon, and chemical oxygen demand were found to be significant variables for veliger mortality in these hard water locations based on linear regression modeling. The three non-target indicator species were adversely affected by EarthTec QZ at concentrations tested. These results indicate that this product has potential as an effective chemical control agent against quagga veligers at low doses, but the aforementioned water quality parameters must be considered with full-scale application to optimize target efficacy, while minimizing exposure to non-target species and costs. [ABSTRACT FROM AUTHOR]

Callinina georgiana (banded mystery snail) and Cipangopaludina japonica (Japanese mystery snail) are two exotic viviparid snail species that have been introduced to North America. These snail species harbor parasites, predate on the eggs of native fish fauna and are prolific in their ability to spread across various freshwater environments. While several recent studies have explored the population structure and range expansion of the species in the United States, none have formally addressed control or eradication strategies. In this study, we attempted to do this by carrying out a series of assays to determine the efficacy of the popular molluscicide, niclosamide monohydrate against both species under both acute and chronic exposure. Our results show that the lethal dose required to achieve 50 % mortality (LD50) for C. georgiana and C. japonica was 1.509 mg/L and 1.296 mg/L respectively. In acute exposure experiments we observed that at higher concentrations, all C. georgiana specimens in experimental treatment tanks were dead but C. japonica never reached 100% mortality even at the highest concentration. In chronic exposure experiments, C. georgiana did not survive more than a week while C. japonica did not survive more than 11 days in the experimental tanks. We conclude that niclosamide is an effective chemical control agent for eradication of invasive mystery snails in North America. However, further studies exploring the effect of the molluscide on non-target species, especially local native fauna, should be investigated prior to any scaled up field applications. [ABSTRACT FROM AUTHOR]

Simple Summary: Limnoperna fortunei, known as the golden mussel, is an invasive bivalve in South America responsible for economic damages in hydroelectric plants due to its ability to attach and grow on the walls of water pipes and tubes. Chemical compounds are often used to control golden mussel infestations in water systems. Here, we investigated the effects of two biocides—MXD-100 ™ and sodium dichloroisocyanurate (NaDCC)—through the assessment of morphological and gene-expression alterations in the gills. Both biocides were able to modulate the expression of defensive genes and morphological changes. Yet, it seems that NaDCC needs continuous exposure to control golden mussel infestation, whereas MXD-100™ can inflict severe damage to the mussels in as little as 24 h. Our results can be used to enhance control strategies for managing mussel growth in water systems, simultaneously reducing the environmental impact associated with costly and harmful chemical releases. Limnoperna fortunei, the golden mussel, is a bivalve mollusk considered an invader in South America. This species is responsible for ecological and economic damages due to its voluminous fouling capability. Chemical biocides such as MXD-100™ and sodium dichloroisocyanurate (NaDCC) are often used to control L. fortunei infestations in hydraulic systems. Thus, we proposed to investigate the effects of different periods (24, 48 and 72 h) of exposure to MXD-100™ (0.56 mg L−1) and NaDCC (1.5 mg L−1) on the gills of L. fortunei through morphological and molecular analyses. NaDCC promoted progressive morphological changes during the analyzed periods and only an upregulation of SOD and HSP70 expression during the first 24 h of exposure. MXD-100™ led to severe morphological changes from the first period of exposure, in addition to an upregulation of SOD, CAT, HSP70 and CYP expression during the first 24 h. In contrast, MXD-100™ led to a downregulation of CAT transcription between 24 and 48 h. In static conditions, NaDCC causes lethal damage after 72 h of exposure, and that exposure needs to be continuous to achieve the control of the species. Meanwhile, the MXD-100™ treatment presented several effects during the first 24 h, showing acute toxicity in a shorter period of time. [ABSTRACT FROM AUTHOR]

The Asian clam Corbicula fluminea is a native aquatic species in Eastern Asia and Africa but has become one of the ecologically and economically harmful invasive species in aquatic ecosystems in Europe, North America, and South America. Due to their natural characteristics as a hermaphroditic species with a high fecundity and dispersal capacity, Asian clams are extremely difficult to eradicate once they have infiltrated a waterbody. This is an emerging issue for states in the Northeastern United States, as Asian clams expand their range farther North due to climate change. There has been extensive research conducted to develop chemical treatments for reactively controlling invasive mollusc populations and proactively preventing their further spread. However, treatments are mostly targeted toward biofouling bivalves in industrial settings. A comprehensive review of Asian clam chemical treatments used in natural open-water systems was performed to evaluate molluscicides and identify the toxicity ranges of emerging treatments that maximize Asian clam mortality and minimize the negative impact on water quality and non-target species. The potential chemical applications in Asian clam control and management are summarized in this report to assist resource managers and practitioners in invasive Asian clam management.

Pomacea canaliculata, as an invasive exotic species in Asia, can adversely affect crop yields, eco-environment, and human health. Application of molluscicides containing metaldehyde is one effective method for controlling P. canaliculata. In order to investigate the effects of metaldehyde on adult snails, we conducted acute toxicological experiments to investigate the changes in enzyme activities and histopathology after 24 h and 48 h of metaldehyde action. The results showed that the median lethal concentrations (LC) of metaldehyde on P. canaliculata were 3.792, 2.195, 1.833, and 1.706 mg/L at exposure times of 24, 48, 72, and 96 h, respectively. Treatment and time significantly affected acetylcholinesterase (AChE), glutathione S-transferase (GST), and total antioxidant capacity (TAC) activity, with sex significantly affecting AChE, GST, and TAC activity and time significantly affecting carboxylesterase (CarE). In addition, the interaction of treatment and time significantly affected the activity of GST, CarE and TAC. In addition, histopathological changes occurred in the digestive glands, gills and gastropods of apple snail exposed to metaldehyde. Histological examination of the digestive glands included atrophy of the digestive cells, widening of the hemolymph gap, and an increase in basophils. In treated snails, the hemolymph gap in the gills was widely dilated, the columnar cells were disorganized or even necrotic, and the columnar muscle cells in the ventral foot were loosely arranged and the muscle fibers reduced. The findings of this study can provide some references for controlling the toxicity mechanism of invasive species.

One of the most significant neglected tropical diseases that have a detrimental effect on economic and public health criteria is Schistosomiasis. Therefore, there is a permanent and urgent need to find alternative means of biological control. Ferula hermonis is a herbaceous plant with various pharmaceutical properties and is known for its endocrine-disrupting effects. The objective of the present study was to investigate the molluscicidal activity of F. hermonis roots methanol extract against Biomphalaria alexandrina snails. The experimental results showed that F. hermonis extract has a molluscicidal activity against adult B. alexandrina snails at LC50 (14.2 mg/l) and LC90 (18.1 mg/l). Exposure of snails to sublethal concentrations LC5 (8.3 mg/l) and LC10 (9.8 mg/l) of the extract considerably lowered snail fertility and egg-laying capacity. In addition, results detected an endocrine-disrupting influence where it caused fluctuations in the levels of the three steroid sex hormones (Testosterone, Estradiol (E2), and Estrogen) following acute and chronic exposure of adult B. alexandrina snails to the sublethal doses of the tested extract. Regarding biochemical alterations, glucose and total lipids levels increased significantly, while protein and albumin contents decreased following exposure to sublethal concentrations, compared to the control snails. The sublethal concentrations (LC5, LC10, and LC50) of F. hermonis roots methanol extract exerted noticeable DNA damage in B. alexandrina snails, whereas LC10 was the most genotoxic concentration with 18.20±0.09% tailed cells and 10.54±0.58 px tail length. F. hermonis roots methanol extract can be considered a promising biocontrol agent against B. alexandrina snails, the intermediate host of Schistosoma mansoni in Egypt, via interference with the reproduction processes, and subsequently reducing the population size of snails in endemic areas. [ABSTRACT FROM AUTHOR]

Objective: To assess the molluscicidal effect of the eco-friendly green synthesized neem silver nanoparticles (neem-Ag NPs) against Biomphalaria alexandrina, the snail intermediate host for Schistosoma mansoni, and their cercaricidal potential. Methods: Methanol extracts from neem fruits were used for green synthesis of neem-Ag NPs. The neem-Ag NPs were characterized using UV-visible absorption spectra, dynamic laser light scattering technique, and transmission electron microscopy. The potential molluscicidal effect against adult and juvenile Biomphalaria alexandrina and the effect of the sub-lethal concentration on hatching of snail eggs and Schistosoma mansoni cercariae were evaluated. Results: The surface plasmon resonance of neem-Ag NPs showed a sharp absorption peak at λmax = 518 nm together with multiple peaks. The hydrodynamic diameter was (77.15±34.53) nm, the polydispersity index (0.338±0.000) and the zeta-potential −14.07 mV. Moreover, transmission electron microscopy showed that the average size of the nanoparticles was (27±2) nm. Agglomeration was evident and a light-colored capping layer could be seen coating the nanoparticles. Juvenile snails (LC50: 0.83 ppm) were more susceptible to neem-Ag NPs than adults (LC50: 1.07 ppm). In addition, neem-Ag NPs and neem at LC50 concentrations inhibited the egg-hatching of snails and showed cercaricidal activity in a time-dependent manner. Conclusions: Neem-Ag NPs have lethal activities against Biomphalaria alexandrina snails and their eggs, as well as Schistosoma mansoni cercariae. Hence, neem-Ag NPs could be a potential agent to control schistosomiasis.

Objective: To evaluate the efficacy of Alstonia congensis green-synthesized nanoparticles as a molluscicide against snail hosts of trematodes. Methods: The ethanolic leaf extract of Alstonia congensis was used to synthesize silver nanoparticles. The formulation was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, and scanning electron microscope/energy-dispersed X-ray. The ovicidal and molluscicidal activities of the Alstonia congensis extract and its nanoparticles were tested against Physa acuta and Bulinus forskalii at different concentrations. Results: The green-synthesized nanoparticles inhibited embryonic development within the egg masses of the two snails in all the tested concentrations. Alstonia congensis extract did not show molluscicidal properties against adult Physa acuta but showed a very weak activity against Bulinus forskalii. Moreover, the synthesized nanoparticles showed significantly high molluscicidal activity against adult snails within 5-40 min of exposure in a concentration-dependent manner (P

Pyriclobenzuron 11 PBU – pyriclobenzuron.(PBU) is a novel molluscicide developed to control Pomacea canaliculate, and little information on its environmental fate has been published. In this study, the photolysis of PBU in an aqueous environment was simulated using a xenon lamp. Results showed that the photolysis of PBU in water followed first-order kinetics, exhibiting a t0.5 of 95.1 h and 83.6 h in Milli-Q water and river water, respectively. Two main photolysis products 22 PPs – photolysis products.(PPs) were detected by HPLC-UV and identified by UPLC-Q/TOF MS, which were formed via the hydroxylation and photocatalytic hydro-dehalogenation of PBU, respectively. The initial relative abundance of photolysis product 1 33 PP-1 – photolysis product 1.(PP-1) in Milli-Q water was 1.55 times higher than that in river water. PP-1 was detected at 26.5 % and 76.8 % of the maximum relative abundance in the river water and Milli-Q water after 720 h, respectively. Photolysis product 2 44 PP-2 – photolysis product 2.(PP-2) was stable in water because of its weak hydrophilicity. The PP-2 detected after 720 h in Milli-Q water and river water was 93.7 % and 93.5 % of the maximum relative abundance, respectively. Finally, ECOSAR software was used to evaluate the acute aquatic toxicity of PBU and its PPs, revealing that the PPs had lower toxicity levels to non-target aquatic organisms.

Objective: To evaluate the efficacy of Alstonia congensis greensynthesized nanoparticles as a molluscicide against snail hosts of trematodes. Methods: The ethanolic leaf extract of Alstonia congensis was used to synthesize silver nanoparticles. The formulation was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, and scanning electron microscope/energy-dispersed X-ray. The ovicidal and molluscicidal activities of the Alstonia congensis extract and its nanoparticles were tested against Physa acuta and Bulinus forskalii at different concentrations. Results: The green-synthesized nanoparticles inhibited embryonic development within the egg masses of the two snails in all the tested concentrations. Alstonia congensis extract did not show molluscicidal properties against adult Physa acuta but showed a very weak activity against Bulinus forskalii. Moreover, the synthesized nanoparticles showed significantly high molluscicidal activity against adult snails within 5-40 min of exposure in a concentration-dependent manner (P<0.05). Conclusions: The Alstonia congensis-based nanoparticles show molluscicidal activities against adults and embryos of Physa acuta and Bulinus forskalii, and can be further explored as a potent molluscicide for the control of intermediate host of trematode parasites. [ABSTRACT FROM AUTHOR]

Objective: To assess the molluscicidal effect of the eco-friendly green synthesized neem silver nanoparticles (neem-Ag NPs) against Biomphalaria alexandrina, the snail intermediate host for Schistosoma mansoni, and their cercaricidal potential. Methods: Methanol extracts from neem fruits were used for green synthesis of neem-Ag NPs. The neem-Ag NPs were characterized using UV-visible absorption spectra, dynamic laser light scattering technique, and transmission electron microscopy. The potential molluscicidal effect against adult and juvenile Biomphalaria alexandrina and the effect of the sub-lethal concentration on hatching of snail eggs and Schistosoma mansoni cercariae were evaluated. Results: The surface plasmon resonance of neem-Ag NPs showed a sharp absorption peak at λmax = 518 nm together with multiple peaks. The hydrodynamic diameter was (77.15±34.53) nm, the polydispersity index (0.338±0.000) and the zeta-potential -14.07 mV. Moreover, transmission electron microscopy showed that the average size of the nanoparticles was (27±2) nm. Agglomeration was evident and a light-colored capping layer could be seen coating the nanoparticles. Juvenile snails (LC50: 0.83 ppm) were more susceptible to neem-Ag NPs than adults (LC50: 1.07 ppm). In addition, neem-Ag NPs and neem at LC50 concentrations inhibited the egg-hatching of snails and showed cercaricidal activity in a timedependent manner. Conclusions: Neem-Ag NPs have lethal activities against Biomphalaria alexandrina snails and their eggs, as well as Schistosoma mansoni cercariae. Hence, neem-Ag NPs could be a potential agent to control schistosomiasis. [ABSTRACT FROM AUTHOR]

Abstract Background Schistosomiasis is a major, but generally overlooked, tropical disease carried by snails of the genus Biomphalaria, which have a large distribution in Egypt. Control of the intermediate host snail is critical in limiting schistosomiasis spread. On the topic of snails’ management, nanotechnology has gained more interest. Results Copper oxide nanoparticles, characterised by transmission electron microscopy and X-ray diffraction, showed a single crystal structure with an average crystallite size around 40 nm by X-ray diffraction and typical transmission electron microscopy (TEM) image. Also, the UV–VIS spectrophotometer displayed a sharp absorption band of CuO NPs. Molluscicidal activity of copper oxide nanoparticles against B. alexandrina snails was observed. Following exposure to CuO NPs (LC50 and LC90 was 40 and 64.3 mg/l, respectively), there was a reduction in the growth and reproductive rates of treated B. alexandrina at the sub-lethal concentrations, as well as, a drop in egg viability. Moreover, CuO NPs exhibited a toxic effect on miracidiae and cercariae of S. mansoni. Scanning electron microscopy (SEM) investigations of the head-foot and mantle of control and treated snails to the sub-lethal concentrations of CuO NPs (LC10 15.6 mg\l–LC25 27.18 mg\l) indicated morphological alterations in the ultrastructure. Conclusions CuO NPs caused a significant effect against the intermediate hosts of S. mansoni and provide a considerable scope in exploiting local indigenous resources as snail molluscicidal agents.

Eisenia fetida (Annelida, Oligochaeta: Lumbricidae) is a biondicator of soil contamination and susceptible to the action of xenobiotics such as phytosanitary. The objective of this study was to determine the lethal and sublethal effect of three granulated baits based on Metaldehyde and / or Carbaryl on E. fetida. Three bioassays were carried out under a completely randomized design with 4 repetitions and under controlled conditions (20 ± 2°C and 14L: 10O). The experimental unit was a plastic container 11.5 cm in diameter and 11 cm in height, provided with a perforated lid, where 750 g of soil mixed with the doses of each bait and 10 clitellated adult individuals from 200 to 400 mg were placed. The treatments were: 0, 40, 80, 120, 160 and 200 g of Metaldehyde ha-1 (4% active ingredient (a.i.)); 0, 80, 160, 240, 320 and 400 g of Carbaryl ha-1 (8% of a.i.) and 0, 40 + 80, 80 + 160, 120 + 240, 160 + 320 and 200 + 400 g Metaldehyde + Carbaryl ha-1 (4% + 8% of a.i.). In the three bioassays, 100% survival of the individuals was obtained. Regarding the biomass of E. fetida, no changes were detected with the application of the baits at 7, 14, 21 and 28 days after application (DAA) (p> 0.05). On the other hand, there were no differences in the number of cocoons and juveniles at 56 DAA with all baits (p> 0.05). It is concluded that the baits based on Metaldehyde and / or Carbaryl did not cause adverse effects on survival, biomass and reproductive parameters of E. fetida. [ABSTRACT FROM AUTHOR]

The giant African land snail (Lissachatina fulica) is a major pest that damages agricultural products and the environment, along with raising public health concerns. Although various methods have been applied to control these invasive snails, they have various limitations. The use of plant extracts is an alternative control method that is environmentally friendly and can reduce the use of harmful chemicals. This study was established to evaluate the molluscicidal effects of soapberry crude extract and to develop a molluscicide from it to control the giant African land snail. The soapberry (Sapindus rarak) crude extract exerted molluscicidal effects against L. fulica within 4 h. Soapberry concentration of 30% caused snail mortality of nearly 90% in 72 h. This plant extract exerted potential repellent and molluscicidal effects in the laboratory and semi-field experiments, while having no observable toxic effects on the vegetable Brassica rapa L. Thus, S. rarak crude extract at this concentration is suitable for snail control in vegetable plots. [ABSTRACT FROM AUTHOR]

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The invasive golden apple snail Pomacea canaliculata is one of the devastating threats to aquatic ecosystems and wetland agriculture worldwide. Macrolides from microbes display various advantages over other compounds in controlling snails. However, emergence of antibiotic-resistant phenotypes against certain macrolides in the field appeals for exploring more effectively molluscicidal macrolides. Here, two borrelidins, borrelidin BN1 and BN2, from the extract of a Streptomyces strain fermentation were evaluated for molluscicidal potential against P. canaliculata using both immersion and contact bioassay methods. Borrelidin BN1 (borrelidin A) presented a significant molluscicidal activity comparable to the chemical pesticide metaldehyde, and had a much lower median lethal concentration value (LC 50 , 522.984 μg·ml−1) than avermectin B1 at 72 h of contact-killing treatment. Snail growth was inhibited by borrelidin BN1 more than by metaldehyde at sublethal concentrations, consistent with responses of key biochemical parameters. Exposure to borrelidin BN1 decreased the activity of acetylcholinesterase (AChE), glutathione S -transferase (GST), aspartate aminotransferase (AST), alanine aminotransferase (ALT) as well as the levels of energy reserves and sex steroids in snail tissues, while increased the activity of superoxide dismutase (SOD), catalase (CAT), lactate dehydrogenase (LDH) and the level of lipid peroxidation (LPO). Further application assay confirmed that borrelidin BN1 protected crop plant Zizania latifolia from P. canaliculata damage via suppressing snail population density. These findings suggest great potential of borrelidin BN1 as a molluscicide. Additionally, its higher activity than the stereoisomeric borrelidin BN2 (borrelidin F) implied better molluscicidal borrelidins could be acquired through structural optimization. [Display omitted] • Borrelidin BN1 presents a significant molluscicidal activity to P. canaliculata. • Borrelidin BN1 inhibits snail growth and development at sublethal concentrations. • Borrelidin BN1 disrupts snail antioxidative protection and energy/hormone syntheses. • Applying borrelidin BN1 can protect plant via suppressing snail population density. [ABSTRACT FROM AUTHOR]

Copyright of Investigación Agraria is the property of Investigacion Agraria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Schistosomiasis is caused by the intestinal parasite Schistosoma mansoni. Individuals are affected by schistosomiasis when they are exposed to aquatic environments contaminated with Schistosoma cercariae that emerged from the infected intermediate host mollusk of the genus Biomphalaria. The WHO recommends using molluscicidal products to reduce the snail population and disease transmission. The WHO encourages the search for alternative substances in schistosomiasis control. Natural products are seen as a promising alternative because they are abundant in countries where schistosomiasis is endemic and have many different substances in their extracts, impairing cases of resistance. Therefore, the nanoemulsion effect of a butanol-soluble fraction of Sideroxylon obtusifolium leaves was evaluated against three study points in the biological cycle of the disease, that is, adults and young Biomphalaria glabrata , spawning by the host mollusk, and infectious larvae of the parasite. Extract-SOB (butanol fraction) and nano-SOB (nanoemulsion) demonstrated promising activity in adult B. glabrata population control with an LC50 of 125.4 mg/L, an LC90 of 178.1 mg/L, an LC50 of 75.2 mg/L, and an LC90 of 97 mg/L. Nano-SOB presented greater potency against young B. glabrata , with an LC90 of 72.1 mg/L and an LC50 of 58.3 mg/L. Still, relevant activity against S. mansoni cercariae was eliminated in 4 h (LC90: 34.6 mg/L). Nano-SOB reduced viable spawning by approximately 30% at 178.1 and 97 mg/L. Referring to most substances in this extract, quercetin-3-rhamnosyl-(1-6)-galactoside and hyperoside may cause low environmental toxicity and human toxicity according to in silico analysis. Thus, nano-SOB is a promising agent to combat B. glabrata population growth and schistosomiasis transmission. [ABSTRACT FROM AUTHOR]

Schistosomiasis is caused by the intestinal parasite Schistosoma mansoni. Individuals are affected by schistosomiasis when they are exposed to aquatic environments contaminated with Schistosoma cercariae that emerged from the infected intermediate host mollusk of the genus Biomphalaria. The WHO recommends using molluscicidal products to reduce the snail population and disease transmission. The WHO encourages the search for alternative substances in schistosomiasis control. Natural products are seen as a promising alternative because they are abundant in countries where schistosomiasis is endemic and have many different substances in their extracts, impairing cases of resistance. Therefore, the nanoemulsion effect of a butanol-soluble fraction of Sideroxylon obtusifolium leaves was evaluated against three study points in the biological cycle of the disease, that is, adults and young Biomphalaria glabrata, spawning by the host mollusk, and infectious larvae of the parasite. Extract-SOB (butanol fraction) and nano-SOB (nanoemulsion) demonstrated promising activity in adult B. glabrata population control with an LC50 of 125.4 mg/L, an LC90 of 178.1 mg/L, an LC50 of 75.2 mg/L, and an LC90 of 97 mg/L. Nano-SOB presented greater potency against young B. glabrata, with an LC90 of 72.1 mg/L and an LC50 of 58.3 mg/L. Still, relevant activity against S. mansoni cercariae was eliminated in 4 h (LC90: 34.6 mg/L). Nano-SOB reduced viable spawning by approximately 30% at 178.1 and 97 mg/L. Referring to most substances in this extract, quercetin-3-rhamnosyl-(1-6)-galactoside and hyperoside may cause low environmental toxicity and human toxicity according to in silico analysis. Thus, nano-SOB is a promising agent to combat B. glabrata population growth and schistosomiasis transmission.

Schistosomiasis is a tropical disease with socioeconomic problems. The goal of this study was to determine the influence of myco-synthesized nano-selenium (SeNPs) as a molluscicide on Biomphlaria alexandrina snails, with the goal of reducing disease spread via non-toxic routes. In this study, Penicillium chrysogenum culture filtrate metabolites were used as a reductant for selenium ions to form nano-selenium. The SeNPs were characterized via UV-Vis spectrophotometer, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). Myco-synthesized SeNPs had a significant molluscicidal effect on B. alexandrina snails after 96 h of exposure at a concentration of 5.96 mg/L. SeNPs also had miracidicidal and cercaricidal properties against S. mansoni. Some alterations were observed in the hemocytes of snails exposed to SeNPs, including the formation of pseudopodia and an increasing number of granules. Furthermore, lipid peroxide, nitric oxide (NO), malondialdehyde (MDA), and glutathione s-transferase (GST) increased significantly in a dose-dependent manner, while superoxide dismutase (SOD) decreased. The comet assay revealed that myco-synthesized SeNPs could cause breaks in the DNA levels. In silico study revealed that SeNPs had promising antioxidant properties. In conclusion, myco-synthesized SeNPs have the potential to be used as molluscicides and larvicides. [ABSTRACT FROM AUTHOR]

Apple snails are one of the most survived fresh water invasive species that causes massive economic loss to vegetations, especially to the rice fields. They survive against many environmental stressors and are considered as a major pest in water-lodged cultivated area due to their intrusiveness, adaptation mechanisms and survivability. Therefore, there is a need for strategies to control their population. Snails can also be used as pollution bioindicators. Here we review apple snails for their ecotoxic management without compromising environment and co-inhabitants, and their use as semi-sessile invasive ecotoxic marker species. Snails have been found to accumulate 0.19–0.21% biphenyl ethers, 1.65% copper sulphate with 26.7% morality, 1.53–29.7% ivermectin, 43% polybrominated biphenyl ethers, 59% triphenylphosphine oxide, 8–100% of various heavy metals and nanoparticles. Feed intake of apple snails can be enhanced up to 22% with copper supplements, while 17 and 100% mortality can be achieved with niclosamide monohydrate (0.13 mg/L) and tea seed derivatives (0.015 g/L) exposure, respectively. Snails respond to stress factors with up to 29.6% higher lipid peroxides and 1.06% protein carbonyls, along with up to 80, 240 and 127% higher activities of superoxide dismutase, catalase and glutathione peroxidase enzymes, respectively, after cypermethrin exposure. Oppositely, mercury (2–8 mg/L) and aldicarb can reduce their oxygen consumption and acetylcholinesterase activity of up to 88.1 and 96.08%, respectively. [ABSTRACT FROM AUTHOR]

Abstract Background Freshwater snails are the intermediate hosts of a large variety of trematode flukes such as Schistosoma mansoni responsible for one of the most important parasitic diseases caused by helminths, affecting 67 million people worldwide. Recently, the WHO Global Vector Control Response 2017–2030 (GVCR) programme reinforced its message for safer molluscicides as part of required strategies to strengthen vector control worldwide. Here, we present the essential oil from Eryngium triquetrum as a powerful product with molluscicide and parasiticide effect against S. mansoni and the snail intermediate host Biomphalaria glabrata. Methods In the present study, we describe using several experimental approaches, the chemical composition of E. triquetrum essential oil extract and its biological effects against the snail B. glabrata and its parasite S. mansoni. Vector and the free-swimming larval stages of the parasite were exposed to different oil concentrations to determine the lethal concentration required to produce a mortality of 50% (LC50) and 90% (LC90). In addition, toxic activity of this essential oil was analyzed against embryos of B. glabrata snails by monitoring egg hatching and snail development. Also, short-time exposure to sublethal molluscicide concentrations on S. mansoni miracidia was performed to test a potential effect on parasite infectivity on snails. Mortality of miracidia and cercariae of S. mansoni is complete for 5, 1 and 0.5 ppm of oil extract after 1 and 4 h exposure. Results The major chemical component found in E. triquetrum oil determined by GC-FID and GC/MS analyses is an aliphatic polyacetylene molecule, the falcarinol with 86.9–93.1% of the total composition. The LC50 and LC90 values for uninfected snails were 0.61 and 1.02 ppm respectively for 24 h exposure. At 0.5 ppm, the essential oil was two times more toxic to parasitized snails with a mortality rate of 88.8 ± 4.8%. Moderate embryonic lethal effects were observed at the concentration of 1 ppm. Severe surface damage in miracidia was observed with a general loss of cilia that probably cause their immobility. Miracidia exposed 30 min to low concentration of plant extract (0.1 ppm) were less infective with 3.3% of prevalence compare to untreated with a prevalence of 44%. Conclusions Essential oil extracted from E. triquetrum and falcarinol must be considered as a promising product for the development of new interventions for schistosomiasis control and could proceed to be tested on Phase II according to the WHO requirements.

The snail Oncomelania hupensis is the only intermediate host of the highly invasive parasite Schistosoma japonicum. Molluscicide is often used to curb transmission of S. japonicum. Niclosamide, the only World Health Organization (WHO) recognized molluscicide, presents major drawbacks, including high cost and toxicity towards aquatic animals. In the present study, a number of aryl pyrrole derivatives (ADs) were synthesized to serve as potential molluscicides and were tested on O. hupensis. To uncover the underlying mechanisms, adenosine triphosphate (ATP) and adenosine diphosphate (ADP) levels were assessed in the soft body of ADs-exposed O. hupensis, using high performance liquid chromatography (HPLC). The effect of C6 on key points of energy metabolism (the activities of complexes I, III, IV and the membrane potential) was determined. We demonstrated that the Compound 6 (C6, 4-bromo-1-(bromomethyl)-2-(4-chlorophenyl)-5- (trifluoromethyl)-1H-pyrrole-3-carbonitrile) exerted the strongest molluscicidal activity against adult O. hupensis at LC50 of 0.27, 0.19, and 0.13 mg/L for 24, 48, and 72 h respectively. Moreover, we found that the bromide on the pyrrole ring of C6 was essential for molluscicidal activity. Furthermore, the ATP content reduced from 194.46 to 139.75 mg/g after exposure to 1/2 LC50, and reduced to 93.06 mg/g after exposure to LC50. ADP, on the other hand, remained the same level before and after C6 exposure. We found that C6, at 1/2 LC50, reduced the membrane potential of O. hupensis, while no significant changes were observed in the activities of complexes I, III, and IV. C6 was identified with excellent activities on O. hupensis. The obtained structure−activity relationship and action mechanism study results should be useful for further compound design and development. [ABSTRACT FROM AUTHOR]

Mucus is very important for the protection of land snails. It is the second defense line after the shell. This study was conducted to test the effect of acetylcysteine (drug) against the mucus in the foot of a clover land snail, Monacha cartusiana (O.F. Müller 1774), under laboratory and field conditions. Snails were exposed to serial concentrations of the tested compound for seven days as bait. LC50 of the compound was calculated and the effect of ¼ LC50 was tested on Total Protein (TP) and Alkaline phosphatase (ALK). The histopathology of land snail foot was studied after treatment with ¼ LC50. The field performance of the compound was evaluated against M. cartusiana as poison bait 3.6% for 21 days in a clover field at Sumsta district, Beni- Suef Governorate. The laboratory results revealed that the LC50 was 2%, and the most effective concentration was 3.6% which gave 90 % mortality. Moreover, the compound caused high significant effect on TP and ALK with a severe increase in their biochemical parameters. Based on the histopathological effect on the foot, the compound caused focal necrosis in the epithelium and degeneration in the connective tissue. The field results indicated that the compound achieved a 95% reduction in the population of M. cartusiana compared with methomyl (the compound recommended by the Ministry of Agriculture), which gave an 88.0% population reduction in the snails' population. Therefore, acetylcysteine compound can be used as a safe molluscicide in agriculture fields, to reduce the number of pest snails to avoid environmental pollution and the long-term pest resistance to methomyl compound. [ABSTRACT FROM AUTHOR]

The green synthesis method is one of the most economic and ecofriendly approach for preparation of metal oxide nanoparticles. In the current study, Moringa oleifera seed was used for synthesis of Ce2O3/M. oleifera (Ce2O3/MNCs) nano-composite. The bio-composite was characterized using FT-IR, XRD, SEM and HR-TEM. The FTIR analysis confirmed the phytochemical involvement in bio-composite. Its crystalline and size was well demonstrated through X-ray Diffraction and HR-TEM. The TEM images revealed these particles in circle shape with average size of 30 nm. The present investigation showed that Ce2O3/MNCs was toxic to B. alexandrina snails with LC50 of 314.5 mg/L. The survival and the reproductive rates of the snails were significantly reduced after exposing to ¼ and ½ of LC50 of Ce2O3/MNCs. The present study showed that Ce2O3/MNCs has significant ovicidal and larvicidal activities. Also, the exposure to ½ of LC50 of Ce2O3/MNCs showed alterations in the tegmental architectures of the head-foot region, in addition it caused significant damages in both of the hermaphrodite and digestive glands of B. alexandrina. Conclusively, Ce2O3/MNCs nano-composite could be utilized as a new molluscicidal agent for the snails of schistosomiasis.

The New Zealand mud snail (NZMS) Potamopyrgus antipodarum, is an invasive species of freshwater snail that has become established in the United States. Where they establish, NZMSs can achieve very high densities and have negative ecological impacts. The discovery of NZMSs at Page Springs Hatchery (PSH) in 2019 triggered a need for treatment options in a hatchery that would not result in eradication of fish stocks. The effects of a low-dose (30 ppb) treatment of EarthTec® QZ on NZMSs, Page springsnails Pyrgulopsis morrisoni and pond snails Physella virgata were evaluated for 39 days. Pond snails fell to zero live individuals 15 days before NZMSs, which fell to zero live individuals 36 days into treatment. Page springsnails fell to zero live individuals three days after NZMSs. It appears that EarthTec® QZ may be an effective treatment for NZMSs under the conditions tested within PSH. Additional testing needs to be performed to evaluate the potential effects on other non-targets under varying environmental conditions. [ABSTRACT FROM AUTHOR]

Schistosomiasis is a tropical disease with socioeconomic problems. The goal of this study was to determine the influence of myco-synthesized nano-selenium (SeNPs) as a molluscicide on Biomphlaria alexandrina snails, with the goal of reducing disease spread via non-toxic routes. In this study, Penicillium chrysogenum culture filtrate metabolites were used as a reductant for selenium ions to form nano-selenium. The SeNPs were characterized via UV-Vis spectrophotometer, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). Myco-synthesized SeNPs had a significant molluscicidal effect on B. alexandrina snails after 96 h of exposure at a concentration of 5.96 mg/L. SeNPs also had miracidicidal and cercaricidal properties against S. mansoni. Some alterations were observed in the hemocytes of snails exposed to SeNPs, including the formation of pseudopodia and an increasing number of granules. Furthermore, lipid peroxide, nitric oxide (NO), malondialdehyde (MDA), and glutathione s-transferase (GST) increased significantly in a dose-dependent manner, while superoxide dismutase (SOD) decreased. The comet assay revealed that myco-synthesized SeNPs could cause breaks in the DNA levels. In silico study revealed that SeNPs had promising antioxidant properties. In conclusion, myco-synthesized SeNPs have the potential to be used as molluscicides and larvicides.

Schistosomiasis has been controlled for more than 40 years with a single drug, praziquantel, and only one molluscicide, niclosamide, raising concern of the possibility of the emergence of resistant strains. However, the molecular targets for both agents are thus far unknown. Consequently, the search for lead compounds from natural sources has been encouraged due to their diverse structure and function. Our search for natural compounds with potential use in schistosomiasis control led to the identification of an algal species, Laurencia dendroidea, whose extracts demonstrated significant activity toward both Schistosoma mansoni parasites and their intermediate host snails Biomphalaria glabrata. In the present study, three seaweed-derived halogenated sesquiterpenes, (−)-elatol, rogiolol, and obtusol are proposed as potential lead compounds for the development of anthelminthic drugs for the treatment of and pesticides for the environmental control of schistosomiasis. The three compounds were screened for their antischistosomal and molluscicidal activities. The screening revealed that rogiolol exhibits significant activity toward the survival of adult worms, and that all three compounds showed activity against S. mansoni cercariae and B. glabrata embryos. Biomonitored fractioning of L. dendroidea extracts indicated elatol as the most active compound toward cercariae larvae and snail embryos.

Schistosomiasis is a serious health issue in tropical regions, and natural compounds have gained popularity in medical science. This study investigated the potential effects of pumpkin seed oil (PSO) on Biomphalaria [B.] alexandrina snails (Ehrenberg, 1831), Schistosoma [S.] mansoni (Sambon, 1907) miracidium, and cercariae. The chemical composition of PSO was determined using gas chromatography/mass spectrometry. A bioassay was performed to evaluate the effects of PSO on snails, miracidia, and cercariae. The results showed no significant mortality of B. alexandrina snails after exposure to PSO, but it caused morphological changes in their hemocytes at 1.0 mg/ml for 24 hours. PSO exhibited larvicidal activity against miracidia after 2 hours of exposure at a LC 50 of 618.4 ppm. A significant increase in the mortality rate of miracidia was observed in a dose- and time-dependent manner, reaching a 100% death rate after 10 minutes at LC 90 and 15 minutes at LC 50 concentration. PSO also showed effective cercaricidal activity after 2 hours of exposure at a LC 50 of 290.5 ppm. Histological examination revealed multiple pathological changes in the digestive and hermaphrodite glands. The PSO had genotoxic effects on snails, which exhibited a significant increase [p≤0.05] in comet parameters compared to the control. The findings suggest that PSO has potential as a molluscicide, miracidicide, and cercaricide, making it a possible alternative to traditional molluscicides in controlling schistosomiasis.

Abstract Background The snail Biomphalaria straminea is one of the intermediate hosts of Schistosoma mansoni. Biomphalaria straminea is also an invasive species, known for its strong capability on peripheral expansion, long-distance dispersal and colonization. Using molluscicides to control snail populations is an important strategy to interrupt schistosomiasis transmission and to prevent the spread of the invasive species. In this study, a series of pyridylphenylurea derivatives were synthesized as potential molluscicides. Their impact on adult snails and egg masses was evaluated. Acute toxicity to fish of the derivatives was also examined to assess their effect on non-target organisms. The preliminary mechanisms of action of the derivatives were studied by enzyme activity assays. Results The representative compounds, 1-(4-chlorophenyl)-3-(pyridin-3-yl)urea (compound 8) and 1-(4-bromophenyl)-3-(pyridin-3-yl)urea (compound 9), exhibited strong molluscicidal activity against adult snails with LD50 values of 0.50 and 0.51 mg/l and potent inhibitory effects on snail egg hatchability with IC50 values of 0.05 and 0.09 mg/l. Notably, both compounds showed good target specificity with potent molluscicidal capability observed in snails, but very low toxicity to local fishes. Furthermore, the exposure of compounds 8 and 9 significantly elevated the enzyme activities of acid phosphatase and nitric oxide synthase of the snails, while no significant change was recorded in the activities of alkaline phosphatase, acetylcholine esterase and superoxide dismutase. Conclusion The results suggested that compounds 8 and 9 of pyridylphenylurea derivatives could be developed as promising molluscicide candidates for snail control.

Objective: To evaluate dogs treated with hemodialysis for severe metaldehyde intoxication and to compare them with conventionally‐managed patients. Design: Retrospective study (2012–2017). Setting: University teaching hospital. Animals: Data from 18 dogs with severe metaldehyde intoxication were analyzed. Eleven dogs were treated with intermittent hemodialysis and 7 managed conventionally. Interventions: None. Measurement and main results: Metaldehyde poisoning was diagnosed based on clinical signs and toxicological analysis or presence of turquoise material in the gastrointestinal content. Clinical signs, additional treatments, dialysis prescription, duration of anesthesia and hospitalization, complications, and outcome were documented. Results were analyzed by t‐test, Mann–Whitney U‐test, and Chi‐square test. P < 0.05 was considered significant. Dialysis was performed for median (range) 180 min (150–420 min) with median of 2.28 L/kg (1.66–4.48 L/kg) blood volume processed. In the hemodialysis group, anesthesia was discontinued at a median of 3.0 hours (1.5–6.7 h) after starting dialysis. The conventional‐group received general anesthesia for a median of 17.5 hours (7.0–30.5 h). No further anticonvulsive treatment was necessary for the hemodialysis group. Time to hospital discharge was shorter in dialyzed dogs (median 18 h; 15–41 h) compared to conventionally treated dogs (median 89 h; 61–168 h; P = 0.0014). Aspiration pneumonia was reported in 5 conventionally treated dogs and none of the dialyzed dogs (P = 0.001). Five dialyzed dogs developed hematoma at the dialysis catheter site. One dog in each group was euthanized. Conclusion: Hemodialysis significantly decreases the requirement for anesthesia and length of hospitalization in dogs with metaldehyde intoxication. Aspiration pneumonia occurred less often in dialyzed patients. Prospective studies are warranted to confirm the clinical utility of hemodialysis in dogs with metaldehyde poisoning. [ABSTRACT FROM AUTHOR]

This study was a follow-up of a previous study that investigated a set of selected fatty acids (FAs; 12 of 56 pools) in Helix pomatia L. as biomarkers of chemical stress induced by applying micro-doses of molluscicides. Here, the potential of rarely used peroxidation (PI) and unsaturation (UI) coefficients were tested as biomarkers. These indices were calculated based on the FA profiles of foot and hepatopancreas tissues of H. pomatia L. Snails were treated with three molluscicides: metaldehyde, methiocarb, and potassium chloride, in three doses each (5, 10, or 15 μl, 0.01% w/v concentration), for 12 weeks, under laboratory conditions. Correlations were evaluated between frequently used oxidation status indicators (catalase, glutathione peroxidase, selenium-dependent peroxidase, superoxide dismutase, glutathione transferase, glutathione reductase, glutathione, carbonyl protein, and thiobarbituric acid reactive substances, in the form of MDA) and UI and PI ratios. These results confirmed that fatty acids could be directly used as biomarkers of exposure and oxidative physiological status in snails. Moreover, the UI and PI, calculated based on FAs, clearly reflected the current oxidation status in snails. These indices changed with the application of micro-doses of molluscicides. In conclusion, these indices could serve as sensitive biomarkers of chemical stress in snails. • PI and UI ratios are effective biomarkers of exposure to molluscicides. • PI and UI are sensitive to very low doses of chemical stressors. • PI and UI panels with selected FAs may be oxidation status parameters. [ABSTRACT FROM AUTHOR]

The concentration of a pesticide used in agriculture not only has implications for effectiveness of pest control but may also have significant wider environmental consequences. This research explores the acceptability of metaldehyde slug pellets at different concentrations by Deroceras reticulatum (Müller, 1774) (Agriolimacidae), and the changes in the health status of the slug when allowed to recover. The highest metaldehyde concentration (5%) yielded the highest slug mortality; however, it also produced the highest proportion of unpoisoned slugs, suggesting the highest level of pellet rejection. Pellets with 1% metaldehyde were as effective as 3% pellets in paralysing a significant proportion of the population after initial pellet exposure; however, more slugs were able to recover from metaldehyde poisoning at 1% metaldehyde compared with 3%. There was no statistically significant difference between the mortality rate of slugs regardless of metaldehyde concentration, suggesting that a lower concentration of metaldehyde may be as effective as a higher concentration.

Copyright of Revista CIENCIA UNEMI is the property of Universidad Estatal de Milagro (UNEMI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant extracts can provide a viable alternative to controlling many crop pests. This study sought to assess the efficacy of vegetable extracts of the unripe fruits of Ilex paraguariensis (yerba maté) for chemical control of the channeled apple snail (Pomacea canaliculata) and of non-target species as the South American catfish (Rhamdia quelen) under laboratory conditions. In P. canaliculata, the LC50 of the decoction extract was 31.39 mg.L−1 and the LT50 was over 26 h. The LC50 of the butanol extract was 24.75 mg.L−1 and the LT50 was in the range of 28 to 32 h. In juvenile R. quelen, the LC50 of the decoction was 17.98 mg.L−1 and the LT50 was in the range of 10–12 h. These extracts are particularly attractive considering the source of compounds and their effectiveness as molluscicides. [ABSTRACT FROM AUTHOR]

From the time it was conceptualized in 1998 to the present, RNAS+ has largely concentrated on research that will generate results to facilitate control, prevention and elimination of its target diseases. Diagnostics has remained an active field of research in order to develop tools that are appropriate for each stage from the first efforts until attempts to block transmission. For example, with regard to schistosomiasis, chemotherapy has excellent impact on morbidity, while better diagnostics and vaccine research have been promoted to complement the other components of the control programme. The need for surveillance in areas where the prevalence has been brought down to very low levels necessitated development of spatio-temporal tools and ecological models based on geographical information systems (GIS) to produce risk and distribution maps for monitoring and evaluation of programme success. New knowledge and experiences in management of the diseases contribute to the formulation of new schemes in management and treatment. Ways of drawing attention to the disease, such as determining disability weights for use in computation of burden of disease, updating epidemiological profile and unravelling new aspects of the disease provide bases for modifying the operation of control programmes as we move forward. Programme evaluation based on reports of actual implementation of activities brought to the fore problems related to the distribution of chemotherapy as well as social, cultural and behavioural aspects of endemic communities. Importantly, this highlighted the necessity of adapting control activities to specific situations of the endemic areas. New models evolving from reviews of this kind and success stories, such us the elimination of lymphatic filariasis (LF) in PR China and Cambodia are presented. [ABSTRACT FROM AUTHOR]