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Over the past several decades, there has been a resurgence of interest in industrial hemp ( Cannabis sativa L., Cannabaceae) cultivation. Besides fibre, seeds and oil, hemp contains high quantity of essential oil (EO). Hop ( Humulus lupulus L., Cannabaceae) is a high-climbing, perennial vine, largely utilized in the brewing industry to add flavour and bitterness to beer. While it is known that hop also contains α- and s-acids, and terpenes that have been found to be toxic, anti-feedant, and repellent for insects and mites, little is known about the bioactivity against problematic species of the hemp EO. In this study, the chemical composition of the EOs from C. sativa and H. lupulus was evaluated by GC–MS, and their acute toxicity was assessed against the Asian tiger mosquito Aedes albopictus (Skuse) (Diptera Culicidae) and, the freshwater bladder snail Physella acuta (Draparnaud) (Mollusca Physidae), two problematic invasive species. Furthermore, we evaluated the toxicity of both EOs against a non-target insect, the mayfly Cloeon dipterum L. (Ephemeroptera Baetidae). Both EOs were toxic against the three tested species. The most effective EO was the C. sativa , able to kill 100% of P. acuta snails starting from 100 μL L −1 . C. sativa LC 50 were 301.560, 282.174 and, 35.370 μL L −1 , while H. lupulus LC 50 were 330.855, 219.787 and, 118.653 μL L −1 against A. albopictus , C. dipterum and P. acuta , respectively. Relative median potency analysis showed that the C. sativa EO was more toxic than H. lupulus against A. albopictus and P. acuta , while H. lupulus was more toxic than C. sativa EO against C. dipterum . The most susceptible species to the two EOs was P. acuta, while A. albopictus resulted the least susceptible one.

Freshwater snails are widely distributed in running water systems. Most of them are feeding on biofilms attached to substrata. We used gastropods with different morphology and potentially different traits to analyse the effect of water currents and substratum roughness on the interactions between grazers and biofilms. The gastropods were exposed to naturally grown biofilms from the River Rhine that differed in age and in their artificial substratum roughness (mimicked by abrasive paper). The experiments were conducted in endless channels with paddle wheels where the current velocity could be set steplessly. The freshwater pulmonates Ancylus fluviatilis and Physella acuta as well as the freshwater prosobranchs Bithynia tentaculata and Potamopyrgus antipodarum were used as model organisms in this investigation. The time the snails remained on the test area related to the substratum roughness, and current velocity was used to compare the performance of the four snail species on different aged biofilms. In one experiment, the locomotive activity of snails was traced. Gastropods left substrata without biofilms and did not show different responses to biofilms of diverse ages with significant differences in their biochemical contents. Grazing by snails altered the biofilms in their chlorophyll- a content, ash-free dry mass, and ash mass. A current velocity above 0.12 m s −1 drove B. tentaculata , P. acuta , and P. antipodarum off the test areas, only A. fluviatilis remained unaffected by the applied current velocities (up to 0.23 m s −1 ). The substratum roughness had no direct influence on the retention time of snails and their locomotive activity on the substrata, whereas the chlorophyll- a content of the biofilm strongly influenced snail activity. Substratum roughness had only an indirect influence on the behaviour of snails contrary to studies on marine snail species.

The fungicide vinclozolin (Vz) is an endocrine disruptor with known anti-androgenic activity in vertebrates. However, there is a lack of information about the Vz mode of action in invertebrates, although some studies have shown that this compound can produce alterations in different species. Transcriptional activity was analyzed in the freshwater snail Physella acuta in order to elucidate putative cellular processes altered by this chemical during a response. In order to identify potential molecular biomarkers, a de novo transcriptome was generated for this species that constitutes a valuable source for future studies. This data, together with some already available data, permitted the identification of several genes related to detoxification mechanisms (Cyp2u1, Cyp3a7, Cyp4f22, GSTo1, GSTt2, and MRP1), stress response (Hsp20.4, Hsp17, Hsp16.6, and Cu,Zn-SOD), the hormonal system (Estrogen Receptor and Hsp90), apoptosis (Casp3), and copper homeostasis (ATOX1). Using quantitative Real-Time polymerase chain reaction, mRNA levels of these genes were examined in snails exposed to 20 or 200 µg/L Vz for 24 h. The results showed an overall weak response, with downregulation of Hsp20.4 and no statistically significant change for the other genes. These findings suggest that P. acuta can manage the concentrations of Vz found in the environment with no relevant activation of the pathways analyzed, although additional studies are needed for longer exposure times and including other metabolic pathways. The new genes described open the range of processes that can be studied at the molecular level in toxicity tests.

Mitochondrial (mt) sequences are frequently used for phylogenetic reconstruction and for identification of species of molluscs. This study expands the phylogenetic range of Hygrophila (Panpulmonata) for which such sequence data are available by characterizing the full mt genome of the invasive freshwater snail Physella acuta (Physidae). The mt genome sequences of two P. acuta isolates from Stubblefield Lake, New Mexico, USA, differed in length (14,490 vs 14,314 bp) and showed 11.49% sequence divergence, whereas ITS1 and ITS2 sequences from the nuclear genome differed by 1.75%. The mt gene order of P. acuta (cox1, P, nad6, nad5, nad1, D, F, cox2, Y, W, nad4L, C, Q, atp6, R, E, rrnS, M, T, cox3, I, nad2, K, V, rrnL, L1, A, cytb, G, H, L2, atp8, N, nad2, S1, S2, nad4) differs considerably from the relatively conserved gene order within Panpulmonata. Phylogenetic trees show that the 13 protein-encoding mt gene sequences (equivalent codons) of P. acuta group according to gastropod phylogeny, yet branch lengths and dN/dS ratios for P. acuta indicate elevated amino acid substitutions relative to other gastropods. This study indicates that mt sequences of P. acuta are phylogenetically informative despite a considerable intraspecific divergence and the atypical gene order in its mt genome.

The red swamp crayfish (Procambarus clarkii) and the bladder snail (Physella acuta) are two invasive aquatic macroinvertebrate species with worldwide distribution that are plagues in rice fields. The purpose of this study was to investigate the possibility of accidental human dispersal of these two species by off-road vehicles. An experimental approach was used owing to the difficulty of obtaining field data on low-probability events such as passive dispersal. Experiments were performed testing the probability of attachment of both organisms to mudguards of off-road vehicles as well as successful transport and release into the receiver water body. Recently-hatched P. clarkii and all P. acuta sizes available in the field were used. Results showed that P. clarkii and P. acuta can be transported in mud adhering to an off-road vehicle. No differences were found in the proportions of adhered organisms between species or for each species at the different densities used because of low overall retrieval. For P. acuta, the attachment probability varied between 0.5% both for 50 and 200 individuals m-2 and 1% for 100 ind. m-2. For P. clarkii, no individuals adhered at 50 ind. m-2, but the probabilities were 1% and 1.5% for 100 and 200 ind. m-2, respectively. A transport-survival experiment showed a mean survival distance of 83.2 km for P. clarkii and 92.2 km for P. acuta under dry conditions. Rain or wet conditions severely reduced successful transport. The proportion of organisms falling into a receiving water body increased with the vehicle's speed while crossing the water. Although the results demonstrated a low probability of occurrence of attachment, they also showed that, if attachment occurs, aquatic organisms have a high chance to be released successfully in a suitable environment after long-distance transport by vehicle. Copyright © 2014 John Wiley & Sons, Ltd.

We investigated nonmarine gastropod fauna on Ulleung Island, an oceanic island in South Korea. Surveys were conducted in June and September 2018, which newly recorded four terrestrial gastropod species (Paludinellassiminea cf. japonica (Pilsbry, 1901), Vallonia costata (Muller, 1774), Meghimatium cf. bilineatum (Benson, 1842) and Ambigolimax sp.) and two freshwater snails (Galba truncatula (Muller, 1774) and Physella acuta (Draparnaud, 1805)). All records of nonmarine gastropods obtained from Ulleung Island so far were compiled as well.

To assess changes in the fauna of freshwater mollusks in the Gharb Plain (Morocco), 200 sites spread over five districts were surveyed between May 2012 and May 2013. A total of 11 species were identified. Physella acuta and Melanopsis praemorsa were most frequently encountered. Bulinus truncatus, an intermediate host of schistosomiasis in Morocco, and Planorbarius metidjensis, an intermediate host of schistosomiasis, were not harvested. The absence of these species may be due to a combination of climatic, biological and anthropogenic factors related to the changes that have occurred in the region.

We present a comprehensive overview of distribution data of non-indigenous mollusc species in Lithuanian inland waters. The data are based on our own observations obtained during 2007–2013 as well as on published and unpublished records from the last 80 years. Four nonindigenous species have been reported to occur in Lithuanian freshwaters: Dreissena polymorpha, Lithoglyphus naticoides, Potamopyrgus antipodarum and Physella acuta. The last species, however, has not been found in Lithuania since the 1950s. D. polymorpha is the most widespread non-indigenous mollusc species in Lithuania. It was observed in 159 out of 226 investigated localities. The other species are less common. L. naticoides was recorded in 43 sites, whereas P. antipodarum was found in 35 localities. In addition to the possible reappearance of P. acuta, four more mollusc species which are currently absent from Lithuanian freshwaters have been reported as non-indigenous from neighbouring countries and thus might potentially invade Lithuanian inland waters in the future.

Two individual physid snails that were collected from the Middle Rio Grande in New Mexico in August 2007 each released a distinct type of digenean cercaria. The cercariae were photographed, and DNA was extracted from both types of cercariae and their snail hosts. Nuclear 18S and 28S rDNA gene sequences of both digeneans and mitochondrial 16S rDNA sequences for the snails were PCR amplified and sequenced directly. Snails were identified as Physella acuta based on sequence data. Phylogenetic analyses relative to a preexisting set of concatenated 18S and 28S sequences from various digeneans, and their associations with P. acuta as snail host, indicated that the 2 parasites represent an unclassified spirorchid and a paramphistome, respectively. The data provided may aid in future resolution of the complete lifecycles of these digenean parasites and in the evaluation of their impact on the fauna in the unique Rio Grande Bosque region of New Mexico.

An in situ bioassay was conducted in three Iberian basins (Ebro, Llobregat and Júcar Rivers) to study the reproductive effects on the freshwater snail Physella acuta. Adult individuals were transplanted in specially designed cylindrical cages. Endpoints included mortality, number of eggs and clutches, number of eggs per clutch and embryo development after 8 days. The results were contrasted with laboratory controls. Significant changes in P. acuta reproduction parameters were detected in all of the rivers: the number of clutches or eggs per snail decreased in the Ebro and Llobregat basins downstream but the number of eggs per clutch increased. The complete development of snails was delayed at some sites downstream in the Júcar and the Ebro basins. The results were contrasted with concentrations of Endocrine Disrupting Compounds (EDCs) and their Estrogenic Equivalent Quotients (EEQs). Positive relationships (Pearson correlations) were identified between the number of eggs per clutch and the total EDC concentration, bisphenol A (BPA) and their EEQs, lipid regulators and diuretics. These endocrine-disrupting chemicals may constitute a toxicological risk for the reproductive performance of snails in the studied basins.

Microscopic plastic items (microplastics) are ubiquitously present in aquatic ecosystems. With decreasing size their availability and potential to accumulate throughout food webs increase. However, little is known on the uptake of microplastics by freshwater invertebrates. To address this, we exposed species with different feeding strategies to 1, 10 and 90 µm fluorescent polystyrene spheres (3–3 000 particles mL−1). Additionally, we investigated how developmental stages and a co-exposure to natural particles (e.g., food) modulate microplastic ingestion. All species ingested microplastics in a concentration-dependent manner with Daphnia magna consuming up to 6 180 particles h−1, followed by Chironomus riparius (226 particles h−1), Physella acuta (118 particles h−1), Gammarus pulex (10 particles h−1) and Lumbriculus variegatus (8 particles h−1). D. magna did not ingest 90 µm microplastics whereas the other species preferred larger microplastics over 1 µm in size. In C. riparius and D. magna, size preference depended on the life stage with larger specimens ingesting more and larger microplastics. The presence of natural particles generally reduced the microplastics uptake. Our results demonstrate that freshwater invertebrates have the capacity to ingest microplastics. However, the quantity of uptake depends on their feeding type and morphology as well as on the availability of microplastics.

It can be suggested that the combined stress of pesticide pollution and suboptimal temperature influences the sensitivity of life stages of aquatic invertebrates differently. The embryo, juvenile, half- and full-life-cycle toxicity tests performed with the snail Physella acuta at different concentrations (0.06–0.5 or 1.0 mg L −1 ) of the model fungicide pyrimethanil at 15, 20 and 25 °C revealed, that pyrimethanil caused concentration-dependent effects at all test temperatures. Interestingly, the ecotoxicity of pyrimethanil was higher at lower (suboptimal) temperature for embryo hatching and F 1 reproduction, but its ecotoxicity for juvenile growth and F 0 reproduction increased with increasing temperature. The life-stage specific temperature-dependent ecotoxicity of pyrimethanil and the high fungicide susceptibility of the invasive snail clearly demonstrate the complexity of pesticide–temperature interactions and the challenge to draw conclusions for the risk of pesticides under the impact of global climate change.

SUMMARY 1. How species reach and persist in isolated habitats remains an open question in many cases, especially for rapidly spreading invasive species. This is particularly true for temporary freshwater ponds, which can be remote and may dry out annually, but may still harbour high biodiversity. Persistence in such habitats depends on recurrent colonisation or species survival capacity, and ponds therefore provide an ideal system to investigate dispersal and connectivity. 2. Here, we test the hypothesis that the wide distributions and invasive potential of aquatic snails is due to their ability to exploit several dispersal vectors in different landscapes. We explored the population structure of Physa acuta (recent synonyms: Haitia acuta, Physella acuta, Pulmonata: Gastropoda), an invasive aquatic snail originating from North America, but established in

In the present study the initial succession of the aquatic macroinvertebrate communities of a newly created shallow lake in a wetland area was monitored during 15 months. Three different types of macroinvertebrate samples (multihabitat, associated to the Phragmites australis stands and associated to the sediment) were collected monthly from May 2004 to July 2005. Additional samples were collected in the reed stand in 2007, when the reed belt had become much taller and thicker. Colonization of the lake was fast, and the colonization sequence was mainly related to the dispersal abilities of the taxa. Habitat-specific changes in the assemblage's structure and composition were registered. The communities associated to the sediment showed a decrease in overall biomass, density and species richness along time. The density of the gastropod Physella acuta and the chironomid species Dicrotendipes pallidicornis, Polypedilum nubifer and Tanytarsus horni decreased significantly, after Chara stands declined; while the chironomid Chironomus riparius became dominant. The epiphytic macroinvertebrate communities associated with the reed stands followed a seasonal pattern, with a warm-period community dominated by the chironomid species Ablabesmyia monilis and Psectrocladius sordidellus-group, and a cold-period community dominated by the chironomid species Cricotopus ornatus and D. pallidicornis.

In fresh waters, non-native invertebrate species preferentially spread via navigation waterways, where they often dominate assemblages. Littoral habitats in navigation waterways are regularly exposed to ship-induced waves. We conducted experiments to test the effects of artificial wave exposure on the relative performance of wide-spread native and non-native species. We compared physiological and behavioural response variables (i.e. growth rate, glycogen content, feeding and swimming activity) of two amphipods (native Gammarus roeselii and non-native Dikerogammarus villosus) and two gastropods (native Bithynia tentaculata and non-native Physella acuta) subject to wave and control (i.e. no wave) treatment flumes across a 6-week period. Growth, and in part glycogen content (as a measure of energy storage), were significantly reduced after exposure to waves in native invertebrates, but not in non-native invertebrates. The reduction in growth may be associated with the disturbance effects of waves, such as the higher swimming activity of G. roeselii and lower food uptake of B. tentaculata. In comparison, the effective hiding behaviour observed for D. villosus and good swimming ability of P. acuta, were identified as important traits facilitating the successful colonisation of the harsh habitat conditions of littoral waterways. Our study demonstrates that artificial wave regimes may contribute significant selective pressure, thus explaining the observed dominance of non-native species in navigational waterways. The success of non-native species under the harsh hydraulic habitat conditions of these socio-economically driven ecosystems may consequently be traced directly to behavioural and/or physiological traits.

Trichodinids, which are ciliate protists, are causative agents of an aquatic animal disease, trichodiniasis, especially among both captive and wild fish. This disease can adversely affect aquaculture and have economic impacts. The objectives of this study were to evaluate the prevalence and mean intensity of Trichodina unionis infection, describe qualitative and quantitative morphological characters, and perform a molecular phylogenetic analysis. The gastropod samples were randomly collected by hand-picking and a hand net. Trichodina unionis was collected by the crushing method under a stereomicroscope. Among all 4977 examined gastropods, 55 individuals of two gastropod species, Gyraulus siamensis and Physella acuta, were found to be infected by T. unionis, with overall prevalence and mean intensity of infection of 1.11% and 16.65, respectively. The characteristics of the denticles indicated T. unionis as having moderately wide blades and moderately curved blade margins, with distinctive bend angles near the distal end. The quantitative characters showed some variations, which could be due to food availability. Molecular phylogenetic analysis conducted with 18S rRNA provided a monophyletic tree of our specimens and previously identified T. unionis, confirming species identification. This study represents the first record of T. unionis in Thailand.

On the basis of data for the period 1998–2008, a faunistic review of invasive species of zoobenthos in the upper reaches of the Kuybyshev Reservoir is given. In total, 30 species are revealed: polychaetes—3; oligochaetes—2; leeches—1; mollusks—5; crustaceans—19 (gammarids—9; corophiums—2; cumaceans and mysids—3 each; narrow-clawed crayfish Astacus leptodactilus and shrimp Macrobrachium nipponense). Invasive species account for 10.8% of the total zoobenthos taxonomic composition. For the first time in the Kuybyshev Reservoir, the following species were noted: polychaete Hypaniola kowalewskii; oligochaete Potamothrix heuscheri; gastropod mollusk Physella acuta; crustaceans Pterocuma pectinata, Stenocuma cercaroides, Dikerogammarus villosus, and Pontogammarus robustoides. Quantitative indices of the main systematic groups and selected mass invader species are presented. The decrease in number and biomass of the majority of species is noted. The exception is the mollusk D. bugensis, whose abundance during the study period increased by approximately a factor of ten.

In aquatic habitats prey often show maximum responsiveness to predators when they are exposed to kairomones and alarm cues in combination. As alarm cues can derive from heterospecific as well as conspecific animals, prey may need to fine tune their responses depending on the taxa with which they co-occur. We used juveniles of the freshwater gastropod, Lymnaea stagnalis L. (great pond snail) to test whether the response to heterospecific alarm cues could be enhanced by cohabitation in the absence of predators, and therefore without the potential for cue association learning. Snails were raised from oviposition alongside one of four other pulmonate species, differing in their phylogenetic relatedness to L. stagnalis, that is, from intragenus to intrasuborder. The antipredator response to heterospecific alarm cues paired with fish kairomones was then compared with the response of L. stagnalis reared in isolation. Cohabitation increased the response to heterospecific alarm cues paired with fish kairomones only when L. stagnalis had developed in the presence of closely related (Lymnaea fusca and Radix balthica) rather than distantly related heterospecifics (Physella acuta and Planorbarius corneus). Hence, in L. stagnalis, learning to recognize heterospecific alarm cues can occur without the need for cue association but the learnt response is constrained by species' relatedness. This result suggests that differential responses observed in studies based on wild-caught animals in response to heterospecific alarm cues may be explained by learning through cohabitation alone.

The problem of introduced plant and animal species has become increasingly imprtant in recent years. Some of these species are found only in greenhouses or thermal waters (Helisoma trivolvis, Menetus dilatatus, Melanoides tuberculata, Planorbella duryi, Holandriana holandrii, Gulella io, Opeas goodallii, Zonitoides arboreus, Pseudosuccinea columella), others expand quickly and efficiently to favourable habitats (Potamopyrgus antipodarum, Physella acuta, Arion rufus, A. lusitanicus, Sinanodonta woodiana, Corbicula fluminea, Dreissena polymorpha) or form small populations there (Ferrisia clessiniana, Lucilla singleyana, Boettgerilla pallens). This paper presents all information on the distribution of invasive mollusc species in Slovakia, both published and unpublished, available to date.

This study was carried out in the Kucuk Menderes River basin in order to determine the water quality and investigate the environmental quality and the applicability of both the Biological Monitoring Working Party (BMWP) and Average Score Per Taxon (ASPT). Monitoring took place in May, July and September 2014 at 10 stations (7 rivers and 3 lakes) according to the method of Intercalibration Common Metrics. Some metrics (BMWP, ASPT, Family Biotic Index, Simpson Diversity Index, Shannon-Wiener Diversity Index, Margalef Diversity Index, dominance, frequency and existence of sensitive species) were calculated. In total, 69 taxa comprising 5,814 individuals were detected. The taxa having the highest frequency rate were Limnodrilus hoffmeisteri (70%), Chironomus (Camptochironomus) tentans (70%), Psammoryctides albicola (60%), Physella acuta (60%), Nais elinguis (60%) and Stylaria lacustris (50%), which are alpha mesosaprobic and polysaprobic species, respectively. The presence and high dominance and frequency rate of these species have indicated basin pollution. Positive indicator species for water quality are Gomphus schneideri, Trithemis annulata, Lindenia tetraphylla, Orthetrum cancellatum, Hydropsyche angustipennis, Cricotopus (Cricotopus) fuscus and Cricotopus (Cricotopus) annulator, while negative indicator species are Culex pipiens, Chironomus (Camptoch.) tentans, Chironomus thummi, Stylaria lacustris and Eristalis tenax. Habitat quality of the Kucuk Menderes River basin was not high (it was found to be heavily polluted/polluted/slightly polluted according to the physicochemical data, BMWP and ASPT) due to physical habitat degradation, urban waste waters, touristic, seasonal dwelling and agricultural activities. © 2016 Institute of Zoology, Slovak Academy of Sciences.

This work aims to determine some ecological aspects of river and terrestrial mollusks of medical-veterinary importance in 13 municipalities of the province of Villa Clara, Cuba during 2013. Samples were collected monthly in 477 mollusk farms. 21 species of fresh water (n=14) and terrestrial (n=7) snails were recorded. Two species were classified as endemic, 15 as local and four as introduced (exotic species). In relation to their frequency of occurrence, 14 species were constant (66.7%), five species were common (23.8%) and two were rare (9.5%). The four main species of freshwater snails were Tarebia granifera, Pomacea poeyana, Physella acuta and Corbicula fluminea in the municipalities of Santa Clara, Placetas, Ranchuelo, Camajuani and Cifuentes. The most representative terrestrial mollusks were Praticolella griseola, Zachrysia auricoma and Galba cubensis, in the municipalities of Santa Clara and Placetas. Positive correlation between richness of species and mollusk abundance was found. Pomacea bridgesii and T. granifera are no less related to the other 20 species of mollusks based on similarity dendrograms. Increasing the maximum temperature and relative humidity decreases the total abundance of mollusks. There is a wide variety of species of mollusks of medicalveterinary importance in the province of Villa Clara, which may constitute an epidemiological risk to the province.

It has long been speculated that Physa acuta, a pulmonate snail widespread and invasive in fresh waters of the old world, may have originated in North America. But the identification of a new-world cognate has been complicated by the confused systematics and taxonomy of the Physidae in America. More than 40 species of physids are currently recognized in the United States, many with variable and overlapping morphology. We have previously established that premating reproductive isolation is negligible among physid snails. Here we report the results from no-choice crosses each involving 2 populations of the widespread American species Physa heterostropha and Physa integra, both with each other and with P. acuta, designed to compare measures of reproductive success between species and between populations within species. Samples of P. acuta were collected from France and Ireland, P. heterostropha from eastern Pennsylvania and South Carolina, and P. integra from southern Indiana and northern Michigan. The 6 intrapopulation controls varied quite significantly in their survival, age at first reproduction, parental fecundity, F1 viability, and F1 fertility under our culture conditions. Measures of survival and reproduction in the 6 interpopulation crosses were generally intermediate, but in no case significantly worse than the more poorly performing control. Thus we were unable to detect evidence of reproductive isolation among our 6 populations of snails from 2 continents. All should be referred to the oldest available nomen, P. acuta.

The New Zealand mud snail Potamopyrgus antipodarum (Hydrobiidae) and the pulmonate Physella acuta (Physidae) have invaded freshwaters in many parts of the world and become established. They co-exist in many streams, lakes and ponds in New Zealand, often at high densities. In the present study the effects of intraspecific- and interspecific interactions between the two species on growth and reproductive output were examined in laboratory mesocosms. In 30-day experiments, growth of Potamopyrgus antipodarum was lower in high density treatments than controls providing evidence for competition at higher densities of both snail species. No competitive effect was obtained for Physella acuta when controls were compared with high-density treatments, but growth was reduced at high densities of conspecifics. Numbers of juveniles released by Potamopyrgus antipodarum in 40 day trials declined at high snail densities and were lowest at high densities of conspecifics. Egg production by Physella acuta was also reduced at high snail densities. However, when the two species were kept together at equal densities (total snail density twice that of controls), egg production by Physella acuta was significantly higher than in all other treatments, suggesting facilitation by the congenor. Lastly, in a 10-day experiment, Physella acuta grew faster in water conditioned by Potamopyrgus antipodarum than in Physa-conditioned water, whereas Potamopyrgus antipodarum showed no growth response to Physella-conditioned water. Overall, our results indicate that growth and reproductive output of both snail species are influenced more by the density of conspecifics than the presence and density of the other species. The successful co-existence of the two species in New Zealand freshwaters therefore may be a reflection, at least in part, of few competitive interactions between them.

Mosquitoes (Diptera: Culicidae) represent a threat for millions of people worldwide, since they act as vectors for important pathogens, including malaria, yellow fever, dengue and West Nile. Second to malaria as the world's most widespread parasitic disease, infection by trematodes is a devastating public health problem. In this study, we proposed two essential oils from plants cultivated in Mediterranean regions as effective chemicals against mosquitoes and freshwater snails vectors of Echinostoma trematodes. Chemical composition of essential oils from Achillea millefolium (Asteraceae) and Haplophyllum tuberculatum (Rutaceae) was investigated. Acute toxicity was evaluated against larvae of the West Nile vector Culex pipiens (Diptera: Culicidae) and the invasive freshwater snail Physella acuta (Mollusca: Physidae), an important intermediate host of many parasites, including Echinostoma revolutum (Echinostomidae). Acute toxicity of essential oils was assessed also on a non-target aquatic organism, the mayfly Cloeon dipterum (Ephemeroptera: Baetidae). Achillea millefolium and H. tuberculatum essentials oils were mainly composed by oxygenated monoterpenes (59.3 and 71.0 % of the whole oil, respectively). Chrysanthenone and borneol were the two major constituents of Achillea millefolium essential oil (24.1 and 14.2 %, respectively). Major compounds of H. tuberculatum essential oil were cis-p-menth-2-en-1-ol and trans-p-menth-2-en-1-ol (22.9 and 16.1 %, respectively). In acute toxicity assays, C. pipiens LC50 was 154.190 and 175.268 ppm for Achillea millefolium and H. tuberculatum, respectively. P. acuta LC50 was 112.911 and 73.695 ppm for Achillea millefolium and H. tuberculatum, respectively, while the same values were 198.116 and 280.265 ppm for C. dipterum. Relative median potency analysis showed that both tested essential oils were more toxic to P. acuta over C. dipterum. This research adds knowledge on plant-borne chemicals toxic against invertebrates of medical importance, allowing us to propose the tested oils as effective candidates to develop newer and safer vector control tools.

The gastropod Physella acuta (Draparnaud, 1805) has been recorded for the first time on shallow shore areas in the Volga Reach of Kuybyshev Water Reservoir, Russia during a sampling in 1998, and for the second time in the same Volga Reach in 2009. The way of its invasion is still unknown. Possibly, this gastropod was introduced from aquariums, and, less possibly, migrated from the lower reaches of the Volga River.

Some freshwater snail species are severe pests to human health or agriculture. We tested the hypothesis that the fish Mylopharyngodon piceus , the black carp, may serve as a biological control agent of two pest snails, Physella acuta (a bank-dwelling snail) and Melanoides tuberculata (a substratum-dwelling snail). Experiments were carried out in the laboratory and under controlled field conditions. In the laboratory, small fish (30–50 g) consumed up to about 300 P. acuta per day. Under field conditions in which snails could not shelter, and where fish were absent, snail densities peaked at 181% of their initial density. Where large M. piceus (4–5 kg) were present, snail densities during this period declined to 79%. Under field conditions in which snails could shelter among boulders, and where fish were absent, snail densities decreased to 80% of their initial density. Where large M. piceus (3–4 kg) were present, snail densities declined to 34%. In the laboratory, small fish (30–100 g) consumed 19 g of M. tuberculata /day at 19°C and 17 g at 25°C. There was no difference in the rate of consumption of snails placed upon the substratum or buried at two depths. We conclude that M. piceus may be an efficient biological control agent of pest snails that shelter among boulders and of substratum-dwelling species that bury into sand.

The morphology of the different larval stages and life cycle ofHypoderaeum conoideum(Trematoda: Echinostomatidae) are described. The freshwater snail speciesLymnaea peregra(Gastropoda: Lymnaeidae) serves as the natural first intermediate host and this andL. corvusserve as experimental first intermediate hosts. These and other freshwater snails, such asPhysella acutaandGyraulus chinensis, in turn serve as second intermediate hosts. Adult worms were obtained from chicks and ducks, but not from rats, mice and golden hamsters. The morphology of the larval stages is compared with previous work onH. conoideum. Several aspects of the biology of the life history stages are described with emphasis on the transmission dynamics of the free-living stages. Differential suitability of the snail species that may act as first and/or second intermediate hosts is studied and discussed.

Effects of chronic application of the fungicide Derosal(R) (active ingredient carbendazim) were studied in indoor macrophyte-dominated freshwater microcosms. The concentrations (0, 3.3, 33, 100, 330 and 1000 mu g/l) were kept at a constant level for 4 weeks. This paper is the second of a series of two; it describes the effects on zooplankton and primary producers and presents an overall discussion. The zooplankton community was negatively affected by the three highest treatment levels (NOECcommunity = 33 mu g/l). At higher treatment levels Cladocera taxa were completely eliminated, while Copepod numbers were reduced. Rotatoria taxa decreased (Keratella quadrata and Lecane sp.) or increased in abundance (Testudinella parva) at the highest treatment level only. Due to the reduced grazing pressure, the abundance of some phytoplankton taxa and the chlorophyll-a content of the phytoplankton increased at the three highest treatment levels (NOECcommunity = 33 mu g/l). This effect was not observed for the periphyton, most probably because the reduced grazing pressure was compensated by the increased abundance of some snail species such as Lymnaea stagnalis and Physella acuta. At the end of the experimental period the biomass of the macrophyte Elodea nuttallii was significantly elevated at the two highest treatment levels. It is hypothesised that carbendazim might have caused, directly or indirectly, the removal of pathogene organisms from the macrophyte. [KEYWORDS: carbendazim; aquatic microcosm; pesticides; ecosystem effects; ecological effect chain]

The morphology of the different stages and life-cycle of Echinostomna friedi n. sp. are described and figured. The freshwater snail Lymnaea peregra (Gastropoda: Lymnaeidae) serves as the natural and experimental first intermediate host and L. corvus and Gyraulus chinensis (Gastropoda: Planorbidae) as experimental first intermediate hosts. These, and Physella acuta (Gastropoda: Physidae), also serve as second intermediate hosts. Adult worms, possessing 37 collar spines, were obtained from naturally infected Rattus norvegicus and experimentally from albino rats, golden hamsters and chickens. Mice were not suitable experimental definitive hosts. E. friedi differs from the most closely related species in the 'revolutum' group mainly in terms of several morphological and biological features of the life-cycle stages and in its cercarial chaetotaxy. The chaetotaxy patterns of the species of the 'revolutum' group are analyzed and the results show that a taxonomic comparison of these species may be carried out on the basis of the number of sensilla in the clusters CIII VI, CIII V2 (or CIII V1 + CIII V2), CIV DL and UVb. These clusters appear adequate to establish taxonomic relationships between different species within the 'revolutum' group.

Biological invasions are a significant component of human-caused global change and is widely regarded as one of the main threats to natural biodiversity. Isolated anthropogenic water bodies created in the areas that are deprived of natural freshwater habitats allow the survival and reproduction of alien species on newly settled sites. They are often small with water level fluctuations causing frequent environmental disturbances. The colonisation success may be the result of the rate of their degradation. The aims of the study were to determine the environmental conditions that affect the existence of alien species of gastropods in this type of aquatic environment and to examine whether the occurrence of non-native species affects the community structure of the native species. This study made it possible to group woodland ponds according to the occurrence of the three invasive species in snail communities and discuss the environmental conditions present in these pond types. Analysis of water properties emphasised the distinctiveness of the selected pond types. In ponds of the Potamopyrgus antipodarum type, we found the highest values of some parameters mainly hardness, conductivity, and content of calcium and chlorides, in contrast with the Physella acuta type, which were characterised by the lowest values except for phosphates and nitrites. In the Ferrissia fragilis type, we found the highest nitrate content. Data on the occurrence of alien species in different water environments play an important role in actions which are taken to prevent new invasions and spread of non-native species as well as to reduce future impacts of invaders.

Effects of a chronic application of the herbicide Afalon (active ingredient linuron) on physicochemical conditions, decomposition of plant litter, and densities of zooplankton and macroinvertebrates were studied in indoor microcosms intended to model drainage ditches. For 28 days, concentrations of 0, 0.5, 5, 15, 50, and 150 micrograms/L linuron were maintained, each in two replicates. The microcosms were dominated by the macrophyte Elodea nuttallii. The functional response of the ecosystem is discussed in relation to shifts in community structure. Treatment effects of linuron on community metabolism, as a direct effect of the inhibition of the photosynthesis of macrophytes and algae, resulted in a decrease in dissolved oxygen and pH, and an increase in alkalinity and conductivity (NOEC 0.5 microgram/L). During the posttreatment period, differences between controls and highest dose fell gradually, but were still significant 7 weeks after the start of linuron application. Decomposition of particulate organic material in litter bags was not affected, despite decreases in DO. The negative effect of linuron on several algae (cryptophytes, diatoms) and the positive effect on the green alga Chlamydomonas resulted in a decrease of several Rotatoria and an increase in Copepoda, and, to a lesser extent, Cladocera. The complete disappearance of the macrophyte E. nuttallii in the 150 micrograms/L microcosms and a 50% reduction of its biomass in the 50 micrograms/L microcosms reduced the numbers of the snail Physella acuta, which normally inhabits macrophytes. Artificial substrates indicated a significant increase in the isopod Asellus aquaticus in the 50 and 150 micrograms/L microcosms during the post-treatment period. This, however, was counteracted by a significant decrease in A. aquaticus at the final harvest. Changes in the ecosystem structure (decline in macrophyte biomass) made the artificial substrates more attractive.

We analyze the dynamics of the gastropod community living in the Ebro Delta ricefields in relation to the cultivation cycle. We found six bassommatophoran species, three of which form more than 97% of total: Physella acuta (Draparnaud), Planorbis planorbis (L.), and Lymnaea ovata (L.).

New analytical methods are available for detecting novel xenobiotic compounds in freshwater systems. Pharmaceuticals are suspected of having effects on freshwater biota at very low concentrations, although the nature of these effects remains unclear. Previous data from the Llobregat River revealed a positive statistical relationship between the biomass of benthic macroinvertebrates and the presence of certain non-steroidal anti-inflammatory drugs (NSAIDs) and beta-blockers. Here, experiments were conducted with the midge Chironomus riparius and the freshwater snail Physella (Costatella) acuta in sediments and water, respectively. The sediments and water were treated with the pharmaceuticals propranolol and indomethacin, with the aims of assaying the effects of these compounds on the organisms and testing the statistical relationships observed in field. The variables measured were survival; C. riparius biomass; and the carbon/nitrogen ratio, lipid content and fertility of freshwater snails. Indomethacin in treated sediments induced an increase in C. riparius biomass, whereas propranolol inhibited growth, albeit at marginal statistical significance. By contrast, indomethacin in water had no effect on any of the parameters measured in P. acuta.

Hepatotoxic microcystins (MCs) produced by cyanobacteria are known to accumulate in gastropods following grazing of toxic cyanobacteria and/or absorption of MCs dissolved in water, with adverse effects on life history traits demonstrated in the laboratory. In the field, such effects may vary depending on species, according to their relative sensitivity and ecology. The aims of this study were to i) establish how various intensities of MC-producing cyanobacteria proliferations alter the structure of gastropod community and ii) compare MC tissue concentration in gastropods in the field with those obtained in our previous laboratory experiments on the prosobranch Potamopyrgus antipodarum and the pulmonate Lymnaea stagnalis. We explored these questions through a one-year field study at three stations at Grand-Lieu Lake (France) affected by different intensities of cyanobacteria proliferations. A survey of the community structure and MC content of both cyanobacteria and gastropods was associated with a caging experiment involving P. antipodarum and L. stagnalis. In total, 2592 gastropods belonging to 7 prosobranch and 16 pulmonate species were collected. However, distribution among the stations was unequal with 62% vs 2% of gastropods sampled respectively at the stations with the lowest vs highest concentrations of MC. Irrespective of the station, pulmonates were always more diverse, more abundant and occurred at higher frequencies than prosobranchs. Only the pulmonate Physa acuta occurred at all stations, with abundance and MC tissue concentration (< or = 4.32 microg g DW(-1)) depending on the degrees of MC-producing cyanobacteria proliferations in the stations; therefore, P. acuta is proposed as a potential sentinel species. The caging experiment demonstrated a higher MC accumulation in L. stagnalis (< or = 0.36 microg g DW(-1) for 71% of individuals) than in P. antipodarum (< or = 0.02 microg g DW(-1) for 12%), corroborating previous laboratory observations. Results are discussed in terms of differential gastropod sensitivity and MC transfer through the food web.

Bu çalışmada, Limonlu çayının mollusk faunasının belirlenmesi amaçlanmıştır. Bütün mollusk türleri çay havzasında seçilen 5 istasyondan toplanmıştır. Çalışma sonucunda Gastropoda sınıfına ait 7 (Theodoxus anatolicus, Melanopsis buccinoidea, Physella acuta, Galba truncatula, Radix labiata, Gyraulus piscinarum, Oxyloma elegans) ve Bivalvia sınıfına ait 1 (Unio bruguierianus) tür olmak üzere toplam 8 mollusk türü tespit edilmiştir. Bulunan tüm türler araştırma alanından ilk defa bildirilmektedir., The main aim of the present study is to identify the mollusk fauna of Limonlu (Lamos) Stream. All mollusc species were collected from 5 stations chosen on the stream basin. As a consequence of the study, in total 8 mollusc species were determined, 7 Gastropoda (Theodoxus anatolicus, Melanopsis buccinoidea, Physella acuta, Galba truncatula, Radix labiata, Gyraulus piscinarum, Oxyloma elegans) and 1 Bivalvia (Unio bruguierianus). All these species are new records for the research area.

Prey selection by Somaniathelphusa sinensis (Parathelphusidae) among five gastropod species (two prosobranchs, three pulmonates) was associated with two snail attributes. First, the degree of defence of the tissues by the shell, approximated by shell weight (SW)/tissue dry weight (M). Snails with the heaviest shells (Sinotaia quadrata: Viviparidae) could not be attacked successfully by any crabs, and those with somewhat lighter shells (Melanoides tuberculata: Thiaridae) were protected from small crabs. Secondly, among those light-shelled snails which could be attacked successfully, prey value (M/handling time, Ht) determined rank order of preference. Biomphalaria straminea (Planorbidae), with the highest M/Ht, was the species most readily eaten. When presented with a single snail species, crabs selected among different-sized B. straminea in a way which maximized M/Ht. This preference was most strongly exhibited by small crabs. A lack of size selection for Radix plicatulus (Lymnaeidae) prey was in agreement with an absence of a clear influence of size on Ht for this species. Manipulation of M/Ht by attaching plastic discs to B. straminea shells (thereby increasing Ht) resulted in patterns of prey selection in accordance with the hypothesis that foraging S. sinensis maximized M/H1. Partial consumption of R. plicatulus, and to a lesser degree Physella acuta (Physidae), was common when groups of snails were presented to individual crabs, and occurred more frequently when large snails were offered. Partial consumption and subsequent rejection of large snails may have masked selection for small prey which were rarely abandoned before being completely eaten. The implications of patterns of prey selection were discussed with reference to the influence of crab predation on snail distribution and abundance in Hong Kong fresh waters.

10 pages, 5 figures, 2 tables.-- PMID: 15006509 [PubMed].-- Printed version published Apr 2004., The concentrations of PCBs, DDTs, HCHs, HCB and OCS were determined in sediments and associated biota, both invertebrates (Physella acuta, Hirudo medicinalis, chironomid larvae, Hydrous pistaceus, Helochares lividus) and vertebrates (Rana perezi), in a temporary aquatic system, a rice field in the Ebro Delta (NE Spain). The qualitative and quantitative distribution of organochlorine compounds in sediments and aquatic biota has been explained by two mechanisms: equilibrium partitioning and/or biomagnification through the trophic web. Nevertheless, bioaccumulation processes are by far more complex, since several biotic and abiotic factors contribute to the observed pollutant loads in the organisms. In this respect, the biological characteristics of the organisms considered (e.g. species, age, lipid contents, feeding habits, etc.), as well as ecological factors (e.g. the habitat of the species and vertical distribution), have been shown to account for the organochlorine levels observed.

The North American gastropod Physella acuta (Draparnaud, 1805) has been recorded for the first time in the Neman River basin, Belarus during a biological survey carried out on 23 August 2007. One specimen was found in a shallow water microhabitat (depth 0.2 m) amongst sand and mud. Most likely, this alien gastropod was introduced either by local aquarium keepers, or from Poland via the Augustov canal.

A study was made of the infectivity of Hypoderaeum conoideum miracidia to a range of laboratory-reared specimens of freshwater snail species (Lymnaea peregra, L. corvus, Physella acuta, and Gyraulus chinensis) that coexist with the parasite in the same natural habitat. L. peregra and L. corvus were found to be equally susceptible to the parasite when specimens of each snail species were singly exposed to miracidia. However, when miracidia could choose either lymnaeid species, they showed a high degree of specificity toward L. peregra. The results obtained suggest that H. conoideum miracidia are capable of distinguishing among these lymnaeids in their orientation to the host. This indicates that miracidia might achieve specificity before actually contacting the snail host and suggests that during the host-snail orientation process they respond to signals different from those generated upon snail contact and invasion. The specificity toward L. peregra observed in H. conoideum miracidia seems to indicate adaptation to the snail community in their natural habitat, resulting in enhancement of their transmission.

The control of alien species is the main challenge for the maintenance the integrity of biodiversity. We present a list of exotic mollusc species recorded in the literature from State of Paraiba (PB), Northeast Brazil, as of April 2014. The total number of species of exotic mollusc recorded is seven, two Bivalvia and five Gastropoda. The Class Bivalvia's species was represented by Isognomon bicolor (Adams, 1845) and Corbicula fluminea (Muller, 1774), and Class Gastropoda's species by Achatina fulica (Bowdich, 1822), Melanoides tuberculata (Muller, 1774), Physella acuta (Draparnaud, 1805), Aplexa marmorata (Guilding, 1828) and Lymnaea columella (Say, 1817).