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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.

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.

Despite the wide distribution and persistence of microplastics (MPs), their interactive effects with molluscicides are unknown. Schistosomiasis, a neglected tropical disease, affects 236.6 million people worldwide. Niclosamide (NCL) is the only molluscicide recommended by the World Health Organization (WHO) and it is used to control the population of Schistosoma spp.'s intermediate host. Thus, this study aimed to evaluate of the interaction between polyethylene (PE) MPs and NCL, and their associated toxicity in the freshwater snail Biomphalaria glabrata (Say 1818). Weathered PE MPs were characterized and theoretical analysis of NCL-MP adsorption nature was made using quantum mechanical calculations. The toxicity of NCL isolated (0.0265 to 0.0809 mg L -1 ) and under interaction with PE MPs (3400 μg L -1 ) in B. glabrata embryos and newly hatched snails was analyzed. In silico analysis confirmed the adsorption mechanisms of NCL into PE MPs. PE MPs decreased the NCL toxicity to both B. glabrata developmental stages, increasing their survival and NCL lethal concentrations, indicating concerns regarding NCL use as molluscicide in aquatic environments polluted by MPs. In conclusion, MPs may change the efficiency of chemicals used in snail control programs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Pyriclobenzuron 1 (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 t 0.5 of 95.1 h and 83.6 h in Milli-Q water and river water, respectively. Two main photolysis products 2 (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 3 (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 4 (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., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Xiangyun Wang reports financial support was provided by China Postdoctoral Science Foundation funded project (2022M722825), the Basic Public Welfare Project of Zhejiang Province of China (No. LGN21C140006) and the National Natural Science Foundation of China (Grant Number 82072309)., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Green nanoparticles (GNPs), mainly green silver nanoparticles (Ag NPs), have been recommended as sustainable and eco-friendly technologies to control vectors and intermediate hosts. The aim of the current study is to carry out a historical and systematic literature review about the use of green plant-based Ag NPs (GP-Ag NPs) to control medically important mosquito, tick and gastropods. Data about the number of studies published per year, geographical distribution of studies (mailing address of the corresponding author), synthesis type (plant species, plant structure and extract types), physicochemical properties of GP-Ag NPs, experimental designs, developmental stages and the toxic effects on mosquitoes, ticks and gastropods were summarized and discussed. Revised data showed that GP-Ag NPs synthesis and toxicity in mosquitoes, ticks and snails depend on plant species, plant part, extract types, exposure condition and on the analyzed species. GP-Ag NPs induced mortality, tissue damage, biochemical and behavioral changes in mosquitoes and reduced their fecundity, oviposition, egg hatching and longevity. Ticks exposed to GP-Ag NPs presented increased mortality and reduced oviposition, while on snails, studies demonstrated mortality, oxidative stress, and DNA damage. Immune responses were also observed in snails after their exposure to GP-Ag NPs. GP-Ag NPs reduced the reproduction and population of several vectors and intermediate hosts. This finding confirms their potential to be used in gastropod control programs. Future studies about current gaps in knowledge are recommended., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Schistosomiasis is a severe illness that caused socioeconomic problems. The present study aimed to investigate the molluscicidal activities of the methanolic extract of Nerium oleander and Tecoma stans on B. alexandrina snails. The present results showed that N. oleander had the higher molluscicidal effect (LC 50 : 138.6 mg/l) than T. stans methanolic extract (LC 50 : 256.0 mg/l). These concentrations had no mortality effects on Daphnia magna during the first 12 h of the exposure, while, they had a cercaricidal activity. Exposure of B. alexandrina snails to the sub lethal concentrations (LC 10 and LC 25 ) of the methanolic extract of either N. oleander or T. stans caused a concentration- dependent significant decrease in their mean total number of hemocyte and hyalinocytes percent, while, both the round small and the granulocytes were increased than the control group. Exposure of B. alexandrina snails to LC 25 of the methanolic extract of N. oleander or T. stans, caused morphological alterations in the hemocytes that were studied by both light and electron microscopy. The sub lethal concentration (LC 25 ) significantly decreased the acetyl cholinesterase activities, acid and alkaline phosphatase levels and the protein content. Histopathological changes occurred in the digestive and the hermaphrodite glands of exposed B. alexandrina snails to LC 25 of the methanolic extracts. These alterations were confirmed by Immunohistochemistry for PCNA and Cyclin D1 expressions. Conclusively, these plants could be used to decrease the spread of schistosomiasis as they are cheap and environmentally safe to replace the synthetic molluscicides for snail control., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Iron oxide nanoparticles (IONPs) have been indicated for the control of parasites and intermediate hosts, as well as applications in several sectors of nanomedicine. However, knowledge regarding its toxicity, mechanisms of action and the role of functionalization in gastropods that act as intermediate hosts of neglected disease parasites is still scarce. The present study aimed to evaluate the toxicity of lauric acid bilayer-functionalized IONPs (LA-IONPs), lauric acid isolated (LA) and iron ions in embryos and newly-hatched Biomphalaria glabrata. The snails were exposed to different concentrations of IONPs, LA and iron ions (1.0-97.65 mg L -1 ) during 144 h (embryos) and 96 h (newly-hatched) and multiple parameters were analyzed, such as mortality, hatching rate, developmental delay, and morphological changes. The results showed that both iron forms (LA-IONPs and iron ions) and LA promoted mortality, hatching inhibition and morphological changes in snail embryos in a concentration-dependent patterns. Embryos also showed iron bioaccumulation after exposure to both iron forms. High toxicity was observed in newly-hatched snails compared to embryos, indicating the protective role of ovigerous masses during the early developmental stages. LA induced high developmental toxicity compared to LA-IONPs and iron ions. Results showed the molluscicide activity of LA-IONPs and isolated LA, indicating their potential use as molluscicide in the snail control program., (Copyright © 2022. Published by Elsevier B.V.)

This study describes for the first time the effect of saline extract and Parkia pendula seed fraction on Biomphalaria glabrata adult embryos and molluscs well as the reproductive parameters (fecundity and fertility) and survival, in addition to cytotoxicity and genotoxicity through the profile of blood cells after exposure to sublethal concentrations. Furthermore, we analyzed the action of both preparations against the cercariae of Schistosoma mansoni and their environmental safety using the bioindicator Artemia salina. The saline extract and fraction showed toxic effects for embryos (CL 90 of 464.25, 479.62, 731.28, 643.28, 408.43 and 250.94, 318.03, 406.12, 635.64, 1.145 mg/mL, for blastula, gastrula, trocophore, veliger and hippo stage respectively), adult snails after 24 h of exposure (CL 90 of 9.50 and 10.92 mg/mL, respectively) with increased mortality after 7 days of observation and significant decrease (p <0.05; p < 0.01 and p < 0.001) in egg mass deposition. At sublethal concentrations, an increase in quantitative and morphological changes in hemocytes was observed, and in the genotoxicity/comet assay analysis, varying degrees of nuclear damage were detected. In addition, the saline extract showed changes in the motility of the cercariae, while the fraction howed toxicity from a concentration of 1.0 mg/mL. The saline extract showed toxicity to A. salina at the highest concentrations (3.0, 4.0 and 5.0 mg/mL), while the fraction did not show ecotoxicity. Thus, the saline extract and fraction was promising in combating schistosomiasis by eliminating the intermediate host and causing alterations and/or mortality to the infectious agent., (Copyright © 2022. Published by Elsevier B.V.)

The molluscicidal action of essential oils have been attributed to the most prevalent terpene compounds. However, molluscicidal properties, mode of action, and toxicity to non-target organisms remain unclear. In this study, the molluscicidal potential of four monoterpenes (camphor, thymol, α-pinene, and 1,8-cineole) against the snail Biomphalaria glabrata, an intermediate host of Schistosoma mansoni, was analyzed. The molluscicide activity of each monoterpene was assessed by the standardized test of the World Health Organization (WHO) and the monoterpenes considered active against B. glabrata were analyzed as inhibitors of the enzymatic activity of acetylcholinesterase (AChE) extracted from snails. In addition, acute toxicity to non-target organisms was assessed against Danio rerio fish. The results show that camphor and 1,8-cineole monoterpenes did not induce snail mortality. Thymol and α-pinene were active against B. glabrata, inducing mortality in concentration-dependent patterns and showing a lethal effect in concentrations compatible with that recommended by the WHO (LC 90 of 7.11 and LC 90 10.34 μg ∙ mL -1 , respectively). The toxic action of thymol and α-pinene on snails indicates that these monoterpenes may account for or largely contribute to the molluscicidal activity of essential oils that contain them as major compounds. Thymol and α-pinene inhibit the AChE of B. glabrata at concentrations higher than those used in the molluscicide test. These monoterpenes show low toxicity to non-target organisms compared to the commercial molluscicide niclosamide. Knowledge about monoterpene toxicity against B. glabrata contributes to its potential use in molluscicidal formulations and in alternatives to the control of snails that host intermediate S. mansoni, a crucial action in the prevention and transmission of schistosomiasis, a neglected tropical disease., (Copyright © 2021. Published by Elsevier B.V.)

Silver nanoparticles (Ag NPs) have been applied in several commercial products due to their antimicrobial properties, while their molluscicide properties, mode of action and toxicity to snail species remain unclear. In this study, the comparative toxicity of polyvinylpyrrolidone (PVP)-functionalized Ag NPs and their dissolved counterpart (Ag ions) was analyzed during the early developmental stages of the freshwater snail Biomphalaria glabrata, intermediate host of Schistosoma mansoni. Ag NPs were synthesized and characterized by multiple techniques, and the snail embryotoxicity was analyzed in terms of mortality, hatching, developmental stages and morphological alterations, while the acute toxicity to newly-hatched snails was analyzed by mortality and behavioral impairments. Results showed that both Ag forms induced mortality, hatching delay and morphological alterations (especially hydropic abnormalities) in snail embryos in a concentration and exposure time dependent patterns. Ag NPs showed low embryotoxic effects and similar toxicity for newly-hatched snails when compared to their dissolved counterparts, indicating that the nanotoxicity was dependent of snail developmental stages. The knowledge about the Ag NP toxicity to different early development stages of B. glabrata contributes to its potential use as molluscicide and control of neglected tropical diseases, including schistosomiasis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2020 Elsevier B.V. All rights reserved.)

Oncomelania hupensis is the intermediate host of Schistosoma japonicum, one of the Schistosoma species that can cause human schistosomiasis. Molluscicidal treatment remains the primary means to control snail. Niclosamide is the only molluscicide recommended by the World Health Organization, and it has been used throughout schistosomiasis-endemic areas in China for almost 30 years. In our previous studies on transcriptomics, morphology, and enzymology of snails after molluscicidal treatment, two effective molluscicides were used, 50% wettable powder of niclosamide ethanolamine salt (WPN) and a new molluscicide derived from niclosamide, the salt of quinoid-2', 5-dichloro-4'-nitro-salicylanilide (LDS, simplified for Liu Dai Shui Yang An). Genes involved in cell structure mintenance, inhibition of neurohumoral transmission, and energy metabolism showed significant differential expression after molluscicide treatments. Damages in the structure of liver and muscle cells were accompanied by inhibited activities of enzymes related to carbohydrate metabolism and energy supply. This study was designed to clarify the dynamic metabolic process by metabonomics, together with the previous transcriptomic and enzymological profiles, to identify potential metabolite markers and metabolism pathways that related to the toxic mechanism of the molluscicide. In total, 56 metabolites were identified for O. hupensis, and 75% of these metabolites consisted of amino acids and derivatives, organic acids, and nucleic acid components. The concentration of glucose, maltose, succinate, choline, and alanine changed significantly after molluscicide treatments. These changes in metabolites mainly occurred in the process of carbohydrate metabolism, energy metabolism, and amino acid metabolism, primarily related to glycolysis/gluconeogenesis, oxidative phosphorylation, and transamination by KEGG pathway identification. Most of the identified pathways were also related to those differentially expressed unigenes and observed enzymes from our previous studies. Inhibited aerobic respiration and oxidative phosphorylation, and energy deficiency were implied further to be the leading causes of the final death of snails after molluscicide treatments. The hypothesised mathematical model in this study identified the rational hysteresis to explain the inconsistency of responses of unigenes, enzymes, and metabolites to molluscicide treatments. This study contributes to the comprehensive understanding of the molluscicidal mechanism in the metabolic process and this could assist in improving existing molluscicide formulations or development of new molluscicides., Competing Interests: Declaration of Competing Interest The authors declare that they have no competing interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Metaldehyde is a potent molluscicide. It is the active ingredient in most slug pellets used for crop protection. This polar compound is considered an emerging pollutant. Due to its environmental mobility, metaldehyde is frequently detected at impacted riverine sites, often at concentrations above the EU Drinking Water Directive limit of 0.1µgL -1 for an individual pesticide. This presents a problem when such waters are abstracted for use in the production of potable water supplies, as this chemical is difficult to remove using conventional treatment processes. Understanding the sources, transport and fate of this pollutant in river catchments is therefore important. We developed a new variant of the Chemcatcher® passive sampler for monitoring metaldehyde comprising a Horizon Atlantic™ HLB-L disk as the receiving phase overlaid with a polyethersulphone membrane. The sampler uptake rate (R s ) was measured in semi-static laboratory (R s = 15.7mLday -1 ) and in-field (R s = 17.8mLday -1 ) calibration experiments. Uptake of metaldehyde was linear over a two-week period, with no measurable lag phase. Field trials (five consecutive 14day periods) using the Chemcatcher® were undertaken in eastern England at three riverine sites (4th September-12th November 2015) known to be impacted by the seasonal agricultural use of metaldehyde. Spot samples of water were collected regularly during the deployments, with concentrations of metaldehyde varying widely (~ 0.03-2.90µgL -1 ) and often exceeding the regulatory limit. Time weighted average concentrations obtained using the Chemcatcher® increased over the duration of the trial corresponding to increasing stochastic inputs of metaldehyde into the catchment. Monitoring data obtained from these devices gives complementary information to that obtained by the use of infrequent spot sampling procedures. This information can be used to develop risk assessments and catchment management plans and to assess the effectiveness of any mitigation and remediation strategies., (Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.)

Metaldehyde is a widely used molluscicide in countries where damage to crops from slugs and snails is a major problem associated with warm and wet winters. In the UK it is estimated that over 8% of the area covered by arable crops is treated with formulated granular bait pellets containing metaldehyde as the main active ingredient. Metaldehyde is hydrophilic (log Kow=0.12), water soluble (200 mg·L(-1) at 17 °C) and has been detected in UK surface waters in the concentration range of typically 0.2-0.6 μg·L(-1) (maximum 2.7 μg·L(-1)) during 2008-2011. In the absence of chronic data on potential hazards to non-target freshwater molluscs, a laboratory study was conducted to investigate the impact of metaldehyde on embryo development in the gastropod Lymnaea stagnalis (RENILYS strain) and using zinc as a positive control. L. stagnalis embryos were exposed to metaldehyde under semi-static conditions at 20±1 °C and hatching success and growth (measured as shell height and intraocular distance) examined after 21 d. Exposure concentrations were verified using HPLC and gave 21 d (hatching)NOEC and (hatching)LOEC mean measured values of 36 and 116 mg MET·L(-1), respectively (equal to the 21 d (shell height)NOEC and (shell height)LOEC values). For basic research purposes, a second group of L. stagnalis embryos was co-exposed to metaldehyde and the pesticide synergist piperonyl butoxide (PBO). Co-exposure to the PBO (measured concentrations between 0.47-0.56 mg·L(-1)) reduced hatching success from 100% to 47% and resulted in a 30% reduction in embryo growth (shell height) in snail embryos co-exposed to metaldehyde at 34-36 mg·L(-1) over 21 d. In conclusion, these data suggest mollusc embryos may have some metabolic detoxication capacity for metaldehyde and further work is warranted to explore this aspect in order to support the recent initiative to include molluscs in the OECD test guideline programme., (Copyright © 2015 Elsevier B.V. All rights reserved.)