Co-Occurrence of Domestic Dogs and Gastropod Molluscs in Public Dog-Walking Spaces and Implications for Infection with Angiostrongylus vasorum: A Preliminary Study

Angiostrongylusvasorum is a helminth parasite of domestic dogs that is increasing in range and prevalence. Its lifecycle requires terrestrial gastropod mollusc (“gastropod”) intermediate hosts, but research is lacking regarding contact risk in situ. We studied co-occurrence between dogs and gastropods in dog-walking spaces in an A. vasorum hotspot in southern England, United Kingdom, with the aim of quantifying environmental and spatio-temporal overlap. We surveyed 390 quadrats and 180 point-counts along 3 km transects at seven sites, yielding 1672 gastropod and 763 dog observations. Common gastropods comprised Arion, Cornu, Monacha, Deroceras, Tandonia, Cochlicella, and Trochulus species. Habitat was the most important factor structuring both gastropod and dog presence and abundance. Likelihood ratio comparisons from conditional probability trees revealed that dogs were 15× more likely to be present on hardstanding surfaces than other habitats but were also present on natural and amenity grassland. Presence of gastropod species associated with high A. vasorum prevalence was 65.12× more likely in woodland/scrub and 62.17× more likely in amenity grassland than other habitats. For gastropods overall, high abundance was 5.82× more likely in woodland/scrub and natural grassland. The findings suggest co-occurrence is highest in amenity and natural grassland, but infection risk is greatest in amenity grassland and woodland/scrub.

VARIABILITY OF SHELL IN GASTROPODS OF THE GENUS BORYSTHENIA LINDHOLM, 1914: TESTING THE STATISTICAL APPROACH IN SEARCH OF TRAITS FOR THE RECENT AND FOSSIL SPECIES DELIMITATION

The gastropod mollusc genus Borysthenia Lindholm, 1914 comprises many species throughout Europe, Asia, North Africa and North America but species delimitation, based mainly on shell morphology (only possible concerning the fossil records) is often disputable. Statistical methods used to test if the shell measurements are reliable traits in delimitation of recent and fossil species in gastropod molluscs of the genus Borysthenia. Our analyses based on quantitative study of over 100 specimens of the Borysthenia species both modern and fossil. It is concluded that the dimensional characteristics of their shell are suitable for the differentiation of both recent and fossil (at least of Pontian age) species through the statistical processing of quantitative data. Through the morphological study of type material, taxonomic status of B. jalpuchense Gozhik, 2002 and B. vinogradovkaense Gozhik, 2002 described from the middle-pontian deposits of Ukraine revised. It is suggested that these taxa are considered two distinct though close relative extinct species. Stratigraphic range of B. jalpuchense is expanded up to the Lower Pontian. All the modern individuals of Borysthenia involved are attributed to B. menkeana (Jelski, 1863) due to their exact correspondence to the lectotype of this species.

Expression Pattern of Nitric Oxide Synthase during Development of the Marine Gastropod Mollusc, Crepidula fornicata

Nitric Oxide (NO) plays a key role in the induction of larval metamorphosis in several invertebrate phyla. The inhibition of the NO synthase in Crepidula fornicata, a molluscan model for evolutionary, developmental, and ecological research, has been demonstrated to block the initiation of metamorphosis highlighting that endogenous NO is crucial in the control of this developmental and morphological process. Nitric Oxide Synthase contributes to the development of shell gland, digestive gland and kidney, being expressed in cells that presumably correspond to FMRF-amide, serotoninergic and catecolaminergic neurons. Here we identified a single Nos gene in embryonic and larval transcriptomes of C. fornicata and studied its localization during development, through whole-mount in situ hybridization, in order to compare its expression pattern with that of other marine invertebrate animal models.

Choosing exotic over the familiar taste: habitat-specific preferences of a malacophagous leech for freshwater snails as prey gastropod establishment?

The spread of freshwater invasive species through aquarium trade poses a threat to the ecosystem, economy and human health. The availability of the exotic freshwater gastropod mollusc, Planorbarius corneus (Linnaeus, 1758) (Gastropoda: Planorbidae), in pet shops in Kolkata, West Bengal, India, raises concern for its potential establishment as an invasive species. Assuming the role of the native predators as a potential biotic barrier for invasion, observations on the predation pattern of the malacophagous leech, Glossiphonia weberi (Blanchard, 1897) (Clitellata: Glossiphoniidae) against P. corneus was made in single as well as in combination with the native snail Indoplanorbis exustus (Deshayes, 1834) (Gastropoda: Planorbidae). Using varying size classes and densities of P. corneus, the predation potential of G. weberi was estimated after a 24 hour period. In another set of experiments, the predation of G. weberi against the snail P. corneus was observed in the presence of I. exustus under four different habitat conditions. The purpose was to justify - (1) the effect of conspecific and heterospecific conditions of the prey availability and (2) the effect of habitat complexity on the predatory efficacy of G. weberi. The results indicated that G. weberi consumed varied numbers of P. corneus, depending on the size and the densities of the prey and predator. Although the prey heterogeneity and complex habitats caused significant reduction of predation on both of the prey species, G. weberi significantly preferred P. corneus over I. exustus in open (P < 0.0001), macrophyte (P = 0.002) and pebbles and macrophyte containing habitats (P < 0.0001). Apparently, G. weberi preferred the exotic snail P. corneus in presence of alternative prey snail I. exustus, under different habitat conditions. Therefore, G. weberi may act as a significant biotic resistance against the colonization and establishment of P. corneus in the Indian context. However, further studies including the multiple prey and predators are required to ascertain the food web level impact of the exotic snail P. corneus in invaded freshwater ecosystems.