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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]

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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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]

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.

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.

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.

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Abstract Schistosomiasis japonica caused by Schistosoma japonicum infection is recognized as a considerable economic and public health concern in Asia. Oncomelania hupensis is the sole intermediate host of S. japonicum. The only molluscicide recommended by World Health Organization (WHO) since 1960s is relative toxic to other aquatic species. In this article, we evaluated the novel molluscicide PPU07 in field trials on their efficiency against O. hupensis and toxicity for local fish. 25% PPU07 sulfate WP exhibited similar molluscicidal effect at 2.0 g/m2 and 2.0 g/m3 in the spraying and immersion trials with the WHO recommended molluscicide niclosamide (1 g/m2 and 1 g/m3). The mortality rates reached 95% and 96%, respectively. Moreover, little toxicity was observed for local fish and other aquatic organisms at the effective molluscicidal concentrations. In all, 25% PPU07 sulfate WP is a promising molluscicide for snail control, particularly in semi-commercial or commercial aquaculture ponds. Graphical abstract Image 10233 Highlights • PPU07 was a newly-synthesized compound. • Two dosing forms of PPU07, namely hydrochloride and 25% sulfate WP formulation were obtained. • 25% PPU07 sulfate WP exhibited similar molluscicidal effects with the only WHO recommended molluscicide – niclosamide. • In contrast to niclosamide, no obvious toxicity was observed for local fish at the molluscicidal concentrations of PPU07. [ABSTRACT FROM AUTHOR]

Nanotechnology has received more attention in the field of control of intermediate hosts. In the present study, copper nanoparticles were fabricated and characterized using scanning electron microscopy (SEM), transmission electron microscope (TEM), x-ray fluorescence (XRF) and fourier transform infrared (FTIR). Improvement of the molluscicidal activity of Anagalis arvensis ethanolic extract was made using CuO NPs by forming plant nanocomposite (ACuO NC). The results showed that ACuO NC has high molluscicidal activity against B. alexandrina snails; recording LC50 and LC90 were 1.76 and 3.16 ppm, respectively. Also, biochemical parameters (Total protein, ALT, AST and ALP) revealed highly significant changes in treated snails with sublethal concentrations (LC10 and LC25) of ACuO NC. However, histopathological changes occurred in the hermaphrodite glands of snails exposed to these concentrations of nanocomposite were detected, where, the ova and sperms degenerated and there were losses of connective tissues between acini. ACuO NC was more safety when tested against the biological indicator Daphnia magna. These observations prove that ACuO NC has potent molluscicidal activity against the intermediate hosts of Schistosoma mansoni with more safety for aquatic environment. [ABSTRACT FROM AUTHOR]

Zebra mussels (Dreissena polymorpha) have continued their spread within inland lakes and rivers in North America despite diligent containment and decontamination efforts by natural resource agencies and other stakeholders. Identification of newly infested waterways by early detection surveillance programs allows for rapid response zebra mussel eradication treatments in some situations. Previous eradication treatments have occurred over a broad range of water temperatures which have influenced the efficacy of molluscicides. Natural resource managers will benefit from knowledge regarding the impacts of water temperature and exposure duration on the toxicity of molluscicides to zebra mussels. In particular, temperature specific data are needed to inform the selection of an effective molluscicide and the proper dose that will induce 100% zebra mussel mortality. We evaluated the influences of temperature and exposure duration on the toxicity of two U.S. EPA-registered (EarthTec QZ and Zequanox) and two nonregistered (niclosamide and potassium chloride) molluscicides to zebra mussels at water temperatures of 7, 12, 17, and 22 °C. Our results indicate that treatment options for the eradication of zebra mussels in waters = 12 °C include 336 h or longer treatments with EarthTec QZ and KCl as well as treatments with niclosamide = 24 h in duration. In waters = 17 °C, multiple toxicant and exposure duration combinations are potentially effective for zebra mussel eradication. On-site or in situ zebra mussel bioassays are a useful tool for the evaluation of treatment efficacy. [ABSTRACT FROM AUTHOR]

Worldwide schistosomiasis remains a serious public health problem with approximately 67 million people infected and 200 million at risk of infection from inhabiting or transiting endemically active regions. Africa, South America, the Caribbean, and the Middle East are the main transmission regions of Schistosoma mansoni. The fight against transmission through the use of molluscicides is not recent and has been advocated as the only activity with the possibility of interruption of transmission in small, epidemiologically active outbreaks. Euphorbia milii var. hislopii (syn. splendens) (Des Moulins, 1826) is the most promising for use in official schistosomiasis control programs according to the WHO. In this review, we show that an understanding of some how E. milii latex affects the snail vector and their parasites from a molecular level to field conditions is lacking. On the other hand, this type of treatment could also provide a rationale for the control of schistosomiasis and other parasitosis. Several publications contribute to enforcing the use of E. milii latex in endemic countries as a cheap alternative or complement to mass drug treatment with praziquantel, the only available drug to cure the patients (without preventing re-infection). [ABSTRACT FROM AUTHOR]

The spreading of alien and invasive species poses new challenges for the ecosystem services, the sustainable production of food, and human well-being. Unveiling and targeting the immune system of invasive species can prove helpful for basic and applied research. Here, we present evidence that a nematode (Phasmarhabditis hermaphrodita)-based molluscicide exerts dose-dependent lethal effects on the golden apple snail, Pomacea canaliculata. When used at 1.7 g/L, this biopesticide kills about 30% of snails within one week and promotes a change in the expression of Pc-bpi, an orthologue of mammalian bactericidal/permeability increasing protein (BPI). Changes in Pc-bpi expression, as monitored by quantitative PCR (qPCR), occurred in two immune-related organs, namely the anterior kidney and the gills, after exposure at 18 and 25 °C, respectively. Histological analyses revealed the presence of the nematode in the snail anterior kidney and the gills at both 18 and 25 °C. The mantle and the central nervous system had a stable Pc-bpi expression and seemed not affected by the nematodes. Fluorescence in situ hybridization (FISH) experiments demonstrated the expression of Pc-bpi in circulating hemocytes, nurturing the possibility that increased Pc-bpi expression in the anterior kidney and gills may be due to the hemocytes patrolling the organs. While suggesting that P. hermaphrodita-based biopesticides enable the sustainable control of P. canaliculata spread, our experiments also unveiled an organ-specific and temperature-dependent response in the snails exposed to the nematodes. Overall, our data indicate that, after exposure to a pathogen, the snail P. canaliculata can mount a complex, multi-organ innate immune response.

The slug, Arion vulgaris Moquin-Tandon, 1855, is a serious pest in agriculture and private gardens. White worm, Enchytraeus albidus Henle, 1837, is an important model of decomposer organism in the terrestrial ecosystem. Saponins, which are secondary metabolites of plants, have previously been shown to have some molluscicidal effect. We investigated which doses of saponins are lethal to the slug, A. vulgaris, and to the non-target organism, E. albidus. An aqueous solution with different concentrations of saponin extract from the bark of the soap tree, Quillaja saponaria Mol., was used in repeat treatments. Slugs were tested in filter paper contact tests as they are naturally exposed to soil contact while crawling. Worms were tested in soil contact tests as they live below ground. It was found that lethality of saponins depends on the slug age group and the environmental temperature. The median lethal concentration (LC50, at 15 °C) on adults was 68.5 g/L, and on juveniles, 96.9 g/L. The slugs were significantly more sensitive at 2 and −1 °C compared to 15 °C. The LC50 (at 6 ℃) on E. albidus was 2.7 g/L (or 0.5 g/kg dry weight of soil), far below those in A. vulgaris (at 15 ℃ and lower). The LC50 for worms at -1℃ was also significantly lower than at 6 ℃. Therefore, we can conclude: (1) that Q. saponaria saponins may be a successful slug control tool used during colder times of the year, but its concentration should be selected according to the age group of A. vulgaris; (2) this measure is more toxic than expected to white worms, which limits its use.

Pyriclobenzuron 1 1 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 t 0.5 of 95.1 h and 83.6 h in Milli-Q water and river water, respectively. Two main photolysis products 2 2 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 3 3 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 4 4 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. [Display omitted] • Photolysis t 0.5 values of PBU in two aqueous environments were 95.1 h and 83.6 h. • The photolysis pathways of PBU were hydroxylation and hydro-dehalogenation. • PP-2 was more stable than PP-1 in aqueous environments. • ECOSAR predicted that aquatic toxicity of PPs was lower than that of PBU. [ABSTRACT FROM AUTHOR]

Schistosomiasis, a parasitic disease caused by trematodes of the genus Schistosoma, is the second most prevalent parasitic disease in the world. It affects around 200 million people. Clinical treatment, prophylaxis, and prevention are performed in countries susceptible to schistosomiasis. In the pharmacological treatment for an acute form of schistosomiasis, the use of antiparasitics, mainly praziquantel, is more common. As an alternative way, prevention methods such as reducing the population of intermediate hosts (mollusks) with molluscicides are important in the control of this disease by interrupting the biological cycle of this etiological parasite. Despite the importance of pharmacological agents and molluscicides, they have side effects and environmental toxicity. In addition, they can lead to the development of resistance enhancing of parasites, and lead to the search for new and effective drugs, including resources of vegetal origin, which in turn, are abundant in the affected countries. Thus, the purpose of this review is to summarize recent studies on botanical products with potential for the control of schistosomiasis, including anti-Schistosoma and molluscicide activities. In addition, species and plant derivatives according to their origin or geographical importance indicating a possible utility of local resources for countries most affected by the disease are presented.

ABSTRACT Schistosomiasis is a disease of global extent reaching populations in social vulnerability. One of the control measures of this parasitosis is the use of molluscicidal substances that can fight snails of the genus Biomphalaria, intermediate hosts of Schistosoma mansoni. The aim of this work was to study the toxic activity of three mangrove species (Avicennia schaueriana Stapf. & Leech, ex Moldenke, 1939, Laguncularia racemosa (L.) CF Gaertn, 1807 and Rhizophora mangle L. 1753) on the biological activities of snails Biomphalaria glabrata. Hydroalcoholic extracts were prepared from the stem and leaves of each of the three plant species to which mollusks were exposed. The phytochemical analysis of plants showed the presence of important metabolites in the leaves and stems of L. racemosa and R. mangle, such as tannins and saponins, but the absence of these metabolites in A. schaueriana. Leaf and stem extracts of the three plant species showed low molluscicidal activity, not reaching the standards determined by the World Health Organization (WHO, 1983). L. racemosa and R. mangle has interfered with motility, feeding and oviposition of snails, unlike the extracts of A. schaueriana, which had no effect on these activities.