Adult Snails Research Articles

Population genetics of invasive Pomacea spp. in Hangzhou City, Zhejiang Province

To investigate the distribution and identify the genetic genetics of invasive Pomacea species in Xihu District, Hangzhou City, so as to understand the spread tendency of Pomacea species. The specimens of Pomacea species were collected from five sites in water systems (lakes, rivers and wetlands) and its costal lands in Xihu District, Hangzhou City in 2017 for morphological identification. Total DNA was isolated from the foot tissues of adult snails for amplification of the COI gene, and haplotype diversity and nucleic acid diversity analyses were performed. In addition, a phylogenetic tree was created based on the haplotype captured from GenBank and those from this study to investigate the phylogenetic relationships. Pomacea specimens, which were preliminarily characterized as Pomacea, were found in ponds, rivers and wetlands in Xihu District of Hangzhou City. A total of 16 sequences were captured from the DNA samples of Pomacea specimens, which belonged to 3 haplotypes, including Hap1, Hap2 and Hap3. A high frequency was seen in Hap1 and Hap3, and a low frequency was found in Hap2. The Pomacea specimens collected from the 5 sites in Xihu Districts included P. canaliculata and P. maculate. The Pomacea specimens with a Hap1 had a close genetic relationship with the P. canaliculata from Argentina, Guangdong Province and Hong Kong Special Administrative Region of China, and the Pomacea specimens with a Hap2 had a close genetic relationship with the P. canaliculata from Argentina, Japan and Guangzhou City of Guangdong Province, China, while the Pomacea specimens with a Hap2 had a close genetic relationship with the P. maculate from Argentina and Brazil. P. canaliculata and P. maculata are present in Xihu District of Hangzhou City. P. maculata may spread to Xihu District through multiple introductions or water flow.

Acute Toxicity, Bioaccumulation, and Bioreduction of Two Antibiotics, Norfloxacin and Ofloxacin, in the Snail Bellamya aeruginosa

Fluoroquinolones (FQs) present in water environments pose threats to aquatic organisms. The concentration of FQs adsorbed onto sediments is generally higher than that in water. Here, we studied the toxicities of two FQ antibiotics, norfloxacin (NOR) and ofloxacin (OFL), on the snail Bellamya aeruginosa, an adaptable benthic animal. For this, we performed acute toxicity experiments on young snails and sub-chronic exposure experiments on adult snails by exposure to the FQs for 1–28 days. The 96 h median effective concentrations showed that NOR toxicity was higher than OFL toxicity, although both NOR and OFL were low-toxicity substances (EC50 > 100 mg L−1). Four concentrations were used in the sub-chronic exposure experiments. Results of the measurement of bioconcentration factors (BCF) showed that OFL accumulation was higher than NOR accumulation in snail tissues. During the depuration period (28–49 days), at low concentrations (2 and 20 μg L−1), both FQs required at least 7 days to reach the maximum residue limit (50 μg kg−1). Conversely, at high concentrations (200 and 2000 μg L−1), 14 days (NOR) and 21 days (OFL) were required. Our results could facilitate management of the environmental risks of antibiotics and conservation of aquatic animals.

Molluscicidal activity of Persea americana Mill. (Lauraceae) stem bark ethanolic extract against the snail Biomphalaria glabrata (Say, 1818): a novel plant-derived molluscicide?

Plant-derived molluscicides have been indicated as biodegradable and low-cost strategies for control of Biomphalaria spp., intermediate host for the Schistosoma. This study evaluated whether the crude ethanolic extract of the Persea americana stem bark has molluscicidal activity against embryos, newly-hatched and adults of Biomphalaria glabrata. The extract was obtained, characterized and its toxicity analyzed by snail embryotoxicity test (144 h) and acute toxicity test with newly-hatching and adult snails (96 h). Results showed the presence of flavonoids, anthraquinone heterosides, coumarins and tannins in the crude ethanolic extract, which showed molluscicidal activity against all life cycle stages of B. glabrata. The LC50 for embryos, newly-hatched and adults were 27.06, 30.60 and 55.55 ppm, respectively. Embryos exposed to the extract at 50 ppm showed hatching inhibition and at 6.2 and 25 ppm had the highest rates of morphological alterations, such as shell malformations and coagulation of the perivitelline substance. Adult snails exposed to the extract at 75 ppm showed a peak of behavioral changes, such as lethargy and shell reclusion, in addition to answers like hemolymph release in most concentrations. Further studies are required, prioritizing toxicity testing on non-target organisms and further elucidation of the active molecules.

A freshwater symbiosis as sensitive bioindicator of cadmium.

The vulnerability of aquatic ecosystems due to the entry of cadmium (Cd) is a concern of public and environmental health. This work explores the ability of tissues and symbiotic corpuscles of Pomacea canaliculata to concentrate and depurate Cd. From hatching to adulthood (4 months), snails were cultured in reconstituted water, which was a saline solution in ASTM Type I water. Then, adult snails were exposed for 8 weeks (exposure phase) to Cd (5 μg/L) and then returned to reconstituted water for other 8 weeks (depuration phase). Cadmium concentration in the digestive gland, kidney, head/foot and viscera (remaining of the snail body), symbiotic corpuscles, and particulate excreta was determined by electrothermal atomic absorption spectrometry. After exposure, the digestive gland showed the highest concentration of Cd (BCF = 5335). Symbiotic corpuscles bioaccumulated Cd at a concentration higher than that present in the water (BCF = 231 for C symbiotic corpuscles, BCF = 8 for K symbiotic corpuscles). No tissues or symbiotic corpuscles showed a significant change in the Cd levels at different time points of the depuration phase (weeks 8, 9, 10, 12, and 16). The symbiotic depuration through particulate excreta was faster between weeks 8 and 10, and then slower after on. Our findings show that epithelial cells of the digestive gland of P. canaliculata and their symbiotic C corpuscles are sensitive places for the bioindication of Cd in freshwater bodies.

Assessing the Impacts of Methoxychlor Exposure on the Viability, Reproduction, and Locomotor Behavior of the Seminole Ramshorn Snail (Planorbella duryi).

In the present study, the effects of short-term methoxychlor exposure on the viability, reproduction, and locomotor behavior of adult seminole ramshorn snails (Planorbella duryi) was assessed. To examine impacts on viability and behavior, individuals were exposed to a water control, vehicle control, or 12.5, 50, 100, 250, 500, or 1000 μg/L of methoxychlor for 48 h; and differences in mortality and locomotor behavior assessed using the freely available ToxTrac software. To determine impacts on reproduction, pairs of snails were exposed to a vehicle control and 12.5, 25, 50, 100, and 250 μg/L of methoxychlor for 9 d; and the number of clutches and eggs laid quantified every 24 h. Methoxychlor concentrations in treatments were determined using gas chromatography. Complete mortality was observed in the 500 μg/L and 1000 μg/L treatments after 48 h and in the 250 μg/L treatment after 9 d. Decreases in the number of egg clutches were observed in all treatments, and the number of eggs laid decreased starting in the 25 μg/L treatment. Decreases in average speed, mobile speed, and total distance traveled, as well as a significant increase in frozen events, were also observed. Our results suggest that methoxychlor exposure causes detrimental effects on several nonlethal endpoints in a nonmodel aquatic invertebrate species and that the analysis of locomotor behaviors serves as a reliable, sensitive endpoint for ecotoxicology testing. Environ Toxicol Chem 2019;39:220-228. © 2019 SETAC.

Molluscicidal and cercaricidal activities of curcumin on Biomphalaria glabrata and Schistosoma mansoni cercariae.

Schistosomiasis control in endemic areas depends on several factors, including chemotherapy, snail control and adequate sanitation. In this context, the employment of compounds isolated from plants is an important issue regarding infection and snail control. The aim of this study was therefore to evaluate the effects of curcumin (CUR), a compound isolated from Curcuma longa, against snails and embryos of Biomphalaria glabrata, which is the most important intermediate host of schistosomiasis in the Americas, as well as in cercariae, the infecting larval stage of Schistosoma mansoni. CUR presented high activity against B. glabrata embryos and moderate activity against newborn and adult snails. The lethal concentration (LC50 ) values after being exposed for 24 h and evaluated for 7 days were 6.54 (95% confidence interval (CI) 5.86-7.30) μgmL-1 for the embryos and 42.29 (95% CI 33.82-52.87) μgmL-1 and 87.69 (95% CI 68.82-111.7) μgmL-1 for the newborn and adult snails, respectively. Moreover, CUR inhibited the development of embryos and egg hatching, and decreased the fecundity rates of adult snails. CUR also demonstrated cercaricidal activity with LC50 values lower than 10μgmL-1 at 1, 3, 6, 9 and 12 h, respectively. Our data show that CUR has potential molluscicidal and cercaricidal activities. Moreover, as a nutraceutical compound that is toxic to both invertebrate host and parasite, CUR has the potential to be explored as a safe new agent to combat schistosomiasis. © 2019 Society of Chemical Industry.

Study on biological characteristics: reproduction and viability of Biomphalaria glabrata as an intermediate host of Schistosoma mansoni

To compare the difference of fertility of Biomphalaria glabrata snails between self-fertilization and cross-fertilization and to observe the circadian rhythm of laying eggs, the effect of light on laying eggs and the tolerance of the snail to water and food deficiency, so as to provide the evidence for control and elimination of B. glabrata snails in the field. Under laboratory conditions, a single B. glabrata egg for self-fertilization was separated and hatched individually, and young snails were raised in different plastic boxes individually. The eggs for cross-fertilization were hatched and the young snails were fed in the same plastic box. The ability of spawn, the development of the eggs, and the number of snails growing from young to adult snails were compared between the self-fertilization and cross-fertilization. The snails were in the water under four environments, all day illumination, all day without illumination, daytime lighting and night without illumination, and daytime without illumination but night lighting. The eggs were collected and counted daily. The circadian rhythm of spawn and the effect of illumination on spawn were observed. The adult snails were divided into 6 groups and exposed to the environments with relative humidity of 0, 65%, 87% and 100%, respectively. The survival rates of the adult snails exposed to the different environments after different time were observed. The adult snails were placed at 25 °C in the oven to remove water content from the soft body of snails. When the dehydration rates of the soft bodies achieved 10%, 20%, 30%, 40%, 50%, 52%, 55%, 57%, 60%, and 70% respectively, the survival rates of the adult snails exposed to the oven were observed. In the 25 °C water, the average laying egg number for 15 days per snail was (8.77 ± 16.92) eggs/snail in the self-fertilization snail. The average laying egg number for 15 days per snail was (149.71 ± 142.28) eggs/snail in the cross-fertilization snails. There was a significant difference between the self-fertilization snail and cross-fertilization snail (t = 0.999 999, P < 0.01). The hatching rate and reproductive maturation rate of the self-fertilization snails and cross-fertilization snails were 50.1% and 78.9%, and 19.3% and 3.8%, respectively, There was a significant difference (the hatching rate: χ2 = 18.18, P < 0.01, the reproductive maturation rate: χ2 = 11.83, P < 0.01) . In the natural environment of daytime with illumination and nighttime with darkness, the amount of laying 20 eggs of B. glabrata snail was (944.07 ± 392.53) eggs/day during a whole day, among them the amount of laying eggs during daytime account for 10.1% and the amount of laying eggs during nighttime account for 89.9%, and the laying egg was given priority to with the night. The above results suggested that the dark environment was conducive to B. glabrata snails to lay eggs. The above results suggested that light can promote the increase of spawning of B. glabrata. When B. glabrata was exposed to the environments with the relative humidity of 0, 65%, 87% and 100% at 25 °C, respectively, and the longest survival times of snails were 7, 70, 150 d and 100 d, respectively. In the 25 °C water, the snails could survive for 50 days without food. The adult snails were placed at 25 °C in the oven to remove water content from the soft body of snails. When the dehydration rates of the soft bodies achieved 10%, 20%, 30%, 40%, 50%, 52%, 55%, 57%, 60%, and 70% respectively, the survival rates of the adult snails exposed to the oven were 100%, 100%, 100%, 100%, 70%, 30%, 0, 0, 0 and 0, respectively. B. glabrata can achieve the reproductive process by cross-fertilization or self-fertilization. There is a significant difference in reproductive ability between the cross-fertilization snail and self-fertilization snail, cross-fertilization is stronger than self-fertilization, but the rate of reproduction in the self-fertilization is higher than that in the cross-fertilization. It is indicated that B. glabrata that survive after the dry season plays an important role in the maintenance of local snail populations and transmission of schistosomiasis mansoni.

Direct and transgenerational effects of an experimental heatwave on early life stages in a freshwater snail

Abstract Global climate change imposes a serious threat to natural populations of many species. Estimates of the effects of climate change‐mediated environmental stresses are, however, often based only on their direct effects on organisms, and neglect the potential transgenerational (e.g. maternal) effects. We tested whether high temperature (i.e. an experimental heatwave), which is known to reduce the performance of adult Lymnaea stagnalis snails, affects the produced offspring (eggs and hatchlings) through maternal effects, and how strong these effects are compared with the effects of direct exposure of offspring to high temperature. We examined the effect of maternal thermal environment (15°C versus 25°C) on per offspring investment (egg size), and the role of both maternal and offspring thermal environments (15°C versus 25°C) on hatching success and developmental time of eggs, offspring survival after hatching, and hatchling size at the age of 5 weeks. Exposure of mothers to high temperature reduced the size of oviposited eggs, increased their hatching success, and also made the onset of hatching earlier. However, high maternal temperature reduced the survival and the final size of hatched juveniles. Direct exposure of offspring to high temperature reduced their survival (both eggs and hatchlings) but increased the developmental rate and growth of those individuals that survived. Interestingly, the magnitude of maternal effects on hatching success of eggs and hatchling survival were similar to the direct effects of high temperature. Our results indicate that heatwaves can affect natural populations through transgenerational maternal effects and that the magnitude of those effects can be equally strong to the direct effects of temperature, although this depends on the trait considered. These findings highlight the importance of considering the transgenerational effects of climate warming when estimating its effects in the wild.

Molluscicidal activities of Tetrapleura tetraptera fruit extract, Aridanin and their particulate formulations on adult and newly hatched Biomphalaria glabrata snails

The study investigated the molluscicidal activities of chloroform/methanol (1:1) extract of Tetrapleura tetraptera and isolated Aridanin. It also developed useable particulate formulation of chloroform methanol extract and Aridanin and evaluated their molluscicidal activities. This is with a view to providing information on development of useable particulate formulations for the control of snail intermediate hosts of schistosomiasis. The plant material was extracted successively in n-hexane (100%), chloroform (100%), chloroform/methanol (1:1) and methanol (100%) respectively by maceration. Bioactivity-guided fractionation of chloroform methanol extract was performed using column chromatography to isolate the active compound, Aridanin. Particulate formulations of chloroform methanol extract and Aridanin were prepared by emulsion solvent evaporation method. Molluscicidal screening on adult and newly hatched Biomphalaria glabrata snails was evaluated according to WHO protocols. The blank polymer formulation, dechlorinated water and Niclosamide served as controls. The result showed that Aridanin demonstrated the highest molluscicidal activity on adult B. glabrata snails with 24 h- LC50 of 1.61 ppm. The chloroform methanol extract had an LC50 value of 23.00 ppm, while particulate formulation of Aridanin and chloroform methanol extract had LC50 of 13.40 and 170.60 ppm respectively. This study showed that newly hatched B. glabrata snails are less susceptible to molluscicides compared to adult snails (P

Integrative Proteomic Analysis of Digestive Tract Glycosidases from the Invasive Golden Apple Snail, Pomacea canaliculata.

The freshwater snail Pomacea canaliculata, an invasive species of global significance, possesses a well-developed digestive system and diverse feeding mechanisms enabling the intake of a wide variety of food. The identification of glycosidases in adult snails would increase the understanding of their digestive physiology and potentially generate new opportunities to eradicate and/or control this invasive species. In this study, liquid chromatography coupled to tandem mass spectrometry was applied to define the occurrence, diversity, and origin of glycoside hydrolases along the digestive tract of P. canaliculata. A range of cellulases, hemicellulases, amylases, maltases, fucosidases, and galactosidases were identified across the digestive tract. The digestive gland and the contents of the crop and style sac yield a higher diversity of glycosidase-derived peptides. Subsequently, peptides derived from 81 glycosidases (46 proteins from the public database and 35 uniquely from the transcriptome database) that were distributed among 13 glycoside hydrolase families were selected and quantified using multiple reaction monitoring mass spectrometry. This study showed a high glycosidase abundance and diversity in the gut contents of P. canaliculata which participate in extracellular digestion of complex dietary carbohydrates. Salivary and digestive glands were the main tissues involved in their synthesis and secretion.

Influence of two management systems on the growth performance of adult African giant land snails (Archachatina marginata)

African gaint land snails are important as means of alleviating acute protein shortage in Nigeria livestock Industries. The present study aimed to study the influence of intensive and extensive management systems on the growth Performance of adult African Giant Land Snails (Archachatina marginata) was carried out in the wildlife domestication unit of the Department of Forest Resources and Wildlife Management, University of Benin, Benin City, Nigeria. Ninety African giant land snails (A. marginata) of average body weight 160.31g ± 0.38g were used for the study. The snails were grouped into two- Group A and Group B. 45 snails in group A were raised in an intensive system of management while 45 snails in group B were raised in an extensive system of management. The data collected on weight gain, shell length increment and shell width increment during the experiment were subjected to student t-Test at 5% significant level. Results showed that there was a significant difference at (p&lt;0.05) in the weight gain. The intensive management system had a higher weight gain of 128.96g with mean value of 4.96 while the extensive management system had a weight gain of 88.37g with mean value of 3.40. There was no significant difference at (p&gt;0.05) in the shell length increment. The snails in the extensive management system had the higher shell length increment of 5.32cm with mean value of 0.20 while the snails in the intensive management system had a shell length increment of 2.43cm with mean value of 0.09. There was a significant difference at (p&lt;0.05) in the shell width increment. The snails in the extensive management system had the higher shell width increment of 9.31cm with mean value of 0.36 while the snails in the intensive management system had a shell width increment of 4.30cm with mean value of 0.17. The snails in the intensive system had a Feed Conversion Ratio of 5.03. For better growth performance of A. marginata in terms of weight gain, snail farmers should raise their snails in an intensive system of management and formulated diet should be used in feeding the snails along side with natural feed such as leaves and fruits.

Biological activities of endozoic fungi isolated from Biomphalaria alexandrina snails maintained in different environmental conditions

ABSTRACT This work aims at studying Biomphalaria alexandrina snails as a source of bioactive compounds. Adult snails were maintained in plastic, mud and cement matrices. Three groups were prepared; under normal laboratory conditions, in slightly low pH conditions, and in high temperature (30°C) conditions. Nine fungal species were isolated from soft tissues of snails. Ethyl acetate and acetone extracts were prepared from each fungal species, and their biological activities were investigated. Paecilomyces variotii extracts were the most effective as antimicrobial agents, while acetone extract of Trichoderma harzianum showed high antioxidant activity. Acetone extracts of Penicillium islandicum and Aspergillus niger were highly active against hepatocellular carcinoma (HepG2) cell lines. Gas chromatography/mass spectrometry analysis of the five effective extracts showed the presence of various compounds. B. alexandrina snails may be regarded as a newly discovered source of beneficial compounds through the metabolites produced by their endozoic fungal strains.

Toxicological effects of Ramalina aspera (lichen) on Biomphalaria glabrata snails and Schistosoma mansoni cercariae

In this study, the molluscicidal activities against Biomphalaria glabrata and cercaricidal activities against Schistosoma mansoni of the ether extract of Ramalina aspera were evaluated. Additionally, toxicity parameters were evaluated at sublethal doses in terms of the influence of the extract on the fertility and fecundity of snails, as well as morphological alterations and quantification of their immunological cells. A test with Artemia salina was also carried out, in order to verify the environmental toxicity of the compound. The ether extract of R. aspera, in which divaricatic acid was identified as the major compound, demonstrated molluscicidal activity at low concentrations against both embryos (LC90 of 22.78, 24.23, 16.63 and 16.03 μg mL−1 for the gastrula, blastula, trochophore and veliger, respectively) and against adult snails (LC90 of 8.66 μg mL−1), after 24 h of exposure. At the sublethal doses, it was possible to observe a decrease in fecundity and quantitative and morphological changes in the defense cells of the exposed snails. In addition, the extract of R. aspera showed a cercaricidal effect on S. mansoni from the concentration of 5.0 μg mL−1, while showing low toxicity to Artemia salina. The ether extract of R. aspera demonstrated effective molluscicidal activity on embryos and adult snails of the species B. glabrata, cercariae of S. mansoni, and presenting low toxicity on Artemia salina. In this way, it could be considered a promising compound in the development of future molluscicidal and cercaricidal agents, thus helping to combat schistosomiasis.

Determining the Salinity Tolerance of Invasive Island Apple Snail Pomacea maculata (Perry, 1810) Hatchlings to Assess the Invasion Probability in Estuarine Habitats in South Carolina, USA

The physiological tolerances of invasive species can be important predictors of geographic range expansion. Further, determining salinity tolerances can inform natural resource managers as to the ability of a freshwater species to invade estuarine habitats. Native to South America, the island apple snail Pomacea maculata (family Ampullariidae) is an invasive freshwater gastropod that is currently established across much of the southeastern United States, including South Carolina. The island apple snail is considered an invasive species because of the negative impacts of its intense grazing, high fecundity, and ability to out-compete native species. Further, the island apple snail can also serve as a potential to host the rat lungworm nematode parasite (Angiostrongylus cantonensis), which can cause eosinophilic meningitis in humans. Despite these known potential impacts, knowledge of biology of P. maculata in South Carolina is limited. The objective of this study was to determine the salinity tolerance of P. maculata hatchlings. Although previous studies on the salinity tolerance of P. maculata have been conducted, physiological tolerances can often vary regionally. Because of this potential for regional differences in salinity tolerance, determining the salinity tolerance of P. maculata specific to South Carolina is important in improving the understanding of its invasion/dispersion potential among brackish habitats in South Carolina. This knowledge will help resource managers to develop more effective control and/or eradication strategies. Newly hatched P. maculata obtained from egg clutches deposited by adult snails in a biosecure laboratory were placed in each of five salinity treatments (0, 4, 8, 12, and 16), and mortality was assessed daily for 14 days. Intraspecific variation at the regional scale in salinity tolerance has been documented in other species; thus, the survival of hatchlings from four separate mating pairs was assessed. Kaplan–Meier survival analysis was conducted to determine median survival probabilities, and differences in mean survival were determined using Kruskal–Wallis tests with post hoc Dunn's tests. An LD50 value was determined by conducting a logistic regression analysis. A survival of 100% was observed at 0 salinity and 0% survival was observed at salinities of both 12 and 16. Survival probabilities at salinities of 4 and 8 were 0.925 and 0.156, respectively. There were no differences in survival among hatchlings from the different mating pairs. In relation to salinity, an LD50 value of 6.39 was calculated. These results demonstrate the ability of P. maculata to survive salinities as high as 8, suggesting that this species could be capable of becoming established in upstream estuarine habitats in coastal South Carolina.

In vitro molluscicidal activity of wormwood (Artemisia dubia) leaves against Oncomelania hupensis quadrasi

There have been many efforts to eradicate the problem of schistosomiasis. One method is to control the growing snail population. This study aimed to determine the molluscicidal activity of wormwood (Artemisia dubia)leaves methanolic extract against adult and juvenile. Using infusion technique, 80% methanol was used as solvent. There were eight treatments used: distilled water (T0(-)1) and 1% methanol (T0(-)2) as negative controls; 0.0002% (2mg/L) niclosamide (T0(+)) as positive control; and 11.121% (T1), 12.478% (T2), 14% (T3), 15.708% (T4) and 17.625% (T5), which were replicated five times with 10 snails per replicate. Results showed that for adults, the wormwood leaves methanolic extract was not statistically significant with the commercially available molluscicide, although 17.625% (T5) resulted in 82% mortality rate. For juveniles, the different extract concentrations resulted in 98 to 100% mortality, which were comparable to 0.0002% (2mg/L) niclosamide and were considered highly effective based on Reik &amp; Keitz (1954) and European Agency for the Evaluation of Medicinal Products (EMEA). Thus, wormwood leaves methanolic extract has a promising molluscicidal activity against adult snails at a concentration of 17.625%, and at all concentrations for the juvenile snails of O. hupensis quadrasi. The LC50 of the adult and juvenile snails were 14.075% and 10.294%, respectively. Secondary metabolites that were found positive during the qualitative phytochemical analysis with the extract were tannins, saponins, and terpenoids. The mortality of the snails can be attributed to the bioactivity of the secondary metabolites present that may be acting in combination or individually.

Tolerance assessment of the aquatic invasive snail Potamopyrgus antipodarum to different post-dispersive conditions: implications for its invasive success

The New Zealand mudsnail (NZMS) Potamopyrgusantipodarum (Gray, 1843) (Tateidae, Mollusca) is a successful invasive species able to alter the functioning of the invaded ecosystems. However, to arrive and establish in new aquatic ecosystems, this snail must survive to the overland translocation through aerial exposure and must tolerate the new physical and chemical conditions of the recipient ecosystem. In this study, we simulated different conditions for the NZMS invasion by combining two air exposure treatments (0 and 20 h) with different physical and chemical conditions of the rehydration water (low and normal water temperatures and normal and high water conductivities). Mortality, behavior and neonate production were compared across treatments. Air exposure caused a high percentage of mortality but survivors tolerated the subsequent abiotic conditions. Low temperatures and high conductivities altered the behavior of adult snails, increasing significantly their reaction time (i.e. time to start normal movement). This may have negative consequences for the survival of this species under natural conditions. Finally, these conditions did not affect significantly the production of neonates. These results supported that the surviving NZMS to a brief period of air exposure possess the ability to acclimate to contrasting abiotic conditions with a potential establishment of new populations and that survivors can reproduce in different abiotic conditions after an air exposure period.

Spatiotemporal Patterns of Infection for Emerging Larval Liver Fluke (Dicrocoelium dendriticum) in Three Species of Land Snail in Southern Alberta, Canada

The control of emerging parasites requires a fundamental knowledge of where and when rates of transmission are high. Data on spatiotemporal patterns of infection are challenging to obtain, particularly for complex life cycle parasites that involve transmission into multiple obligate hosts. The lancet liver fluke, Dicrocoelium dendriticum, has a long history of colonization outside its native host and geographical range in continental Europe. Infection patterns involving adult and metacercarial stages have been characterized for this trematode in a region of emergence in western Canada within co-grazing herbivores and ants, but infection patterns in snail intermediate hosts in this region are unknown. We combined spatiotemporal prevalence surveys with sequence analyses of the cytochrome c oxidase subunit 1 ( COI) barcoding gene from samples of sporocyst tissue in infected snails to confirm that D. dendriticum utilizes 3 sympatric species of Oreohelid land snail ( Oreohelix subrudis, Oreohelix sp., and Oreohelix cooperi) as first intermediate host. Mean prevalence within a total sample of 900 adult snails collected over 1 field season from 6 sites was 9.9 ± 2.4%. For each species of snail, prevalence ranged between 5-30% within monthly samples, with peaks in mid-summer followed by declines in fall. Between-site variation in prevalence was low and non-significant, implying that rates of transmission of D. dendriticum miracidia from domestic stock and wildlife into snails are similar within localized sites, despite high variation in local habitat characteristics and in the structure of the definitive host community.

Biological activity of artemisinin-naphthoquine phosphate on Schistosoma haematobium stages and the vector Bulinus truncatus.

Schistosoma haematobium infection is a major public health problem in most of Africa and the Middle East and praziquantel remains the only drug used for schistosomiasis control, therefore emergence of drug resistance is unavoidable. The antimalarial artemisinin-naphthoquine phosphate combination (co-ArNp) was recently documented to have promising effects on Schistosoma mansoni and its snail host. We conducted this in vitro study to assess the bioactivity of co-ArNp on S. haematobium and its snail vector Bulinus truncatus. Treatment of S. haematobium worms with 1 μg/ml co-ArNp for 24 h reduced worm motility, while 20 μg/ml resulted in 25-100% mortality of adult flukes within 48-72 h. Incubation of S. haematobium miracidia and cercariae with the molluscicidal co-ArNp (50% lethal concentration 7.5 μg/ml) killed all the free larval stages within 40 and 15 min, respectively. Also, exposure of B. truncatus adult snails to 20 ppm of the combined regimen caused a mortality rate of 100% within 24 h. Co-ArNp therapy has also shown encouraging activity against the other major human schistosome, S. haematobium, as well as its vector.

Cellular effects of diquat dibromide exposure: Interference with Wnt signaling and cytoskeletal development

The herbicidal action of diquat dibromide (DD) on plant cells is due primarily to the initiation of reactive oxygen species (ROS) formation, lipoperoxidation, and apoptotic cell death. It has been demonstrated that oxidative stress also occurs in animal cells exposed to high concentrations of DD; however, observations of DD’s effects on animal cells at concentrations below the reported ROS-initiation threshold suggest that some of these effects may not be attributable to ROS-induced cell death. Our results suggest that DD causes disruption of the Wnt pathway, calcium dysregulation, and cytoskeletal damage during development. Using embryos of the pond snail Lymnaea palustris as our model organism, we observed increased mortality, developmental delay and abnormality, altered motility, calcium dysregulation, decreased heart rate, and arrhythmia in embryos exposed to DD. Sperm extracted from adult snails that were exposed to DD exhibit altered motility, increased abundance, and high mortality. Effects were quantified via real-time imaging, heart rate assessment, flow cytometry, and mortality scoring. We propose that there are two models for the mechanism of DD’s action in animal cells: at low concentrations (≤28 µg/L), apoptotic cell death does not occur, but cytoskeletal elements, calcium regulation, and Wnt signaling are compromised, causing irreversible damage in L. palustris embryos; such damage is partially remediated with antioxidants or lithium chloride. At high concentrations of DD (≥44.4 µg/L), calcium dysregulation may be triggered, leading to the establishment of an intracellular positive feedback loop of ROS formation in the mitochondria, calcium release from the endoplasmic reticulum, calcium efflux, and apoptotic cell death. Permanent cellular damage occurring from exposure to sublethal concentrations of this widespread herbicide underscores the importance of research that elucidates the mechanism of DD on nontarget organisms.

Kleptoparasitism and territoriality in the Snail Kite Rostrhamus sociabilis (Accipitriformes: Accipitridae) in the Complejo G\xfcija, El Salvador

We present the observations of some kleptoparasitic and territorial interactions in the Snail Kite (Rostrhamus sociabilis), following focal individuals from January to May 2017 in two wetlands of El Salvador. Those interactions were performed during their food searching and managing of prey on perch. We observed two attempts of kleptoparasitism from Great-tailed Grackle (Quiscalus mexicanus) to R. sociabilis. On the first case, a flock of Q. mexicanus chased an adult Snail Kite, which had captured a snail; on the second case, a male of Q. mexicanus tried to steal a young Snail Kite’s prey, which was managing its prey on perch. On both cases in response to the attack, two individuals chose to change perch to complete the consumption of its prey. We also observed an intent of kleptoparasitism between two male Snail Kites, after the attack, on perch the chased bird released the snail and moved to another site, meanwhile, the attacker ended up eating the snail. We attribute this observation to a kleptoparasitic behavior, related to water stress and variations in prey availability. We recorded Snail Kite’s territorial behavior between the species and against other raptors, as a way to protect their feeding territories. With these observations, we provide some information about the ecological behavior of the species in El Salvador. We stress the need to carry out research related to the interaction between R. sociabilis and Q. mexicanus on its feeding sites, focusing in the effect of water scarcity and snail availability on the behavior of the Snail Kite.