Terrestrial Molluscs Research Articles

The assessment of the genetic structure of bush snail (Fruticicola fruticum) populations based on the nonspecific esterases loci

Using the polymorphic esterases loci, the genetic structure of the gastropod mollusk Fruticicola (Bradybaena) fruticum Мll., most of which lives in the south of the Central Russian Upland, was studied. For comparison, the samples were taken from the Romania, the North Caucasus, the Ural and the Vyatka regions. A total of the 1668 individuals were investigated. Of the 28 studied populations in 11 (39.3%), there was significant shortage of the heterozygotes. The level of the expected heterozygosity fluctuated in the range He = 0.1160.454. Using the non-parametric statistics (Chao1-bc method and 1st order jackknife method), the populations with potentially high and low diversity of the multilocus genotypes were identified. The indicators of the genetic disunity between populations averaged st = 0.276, Fst = 0.292. The principal component analysis and the Mantel correlation criterion Rм = 0.007 showed the absence of a reliable relationship between the geographical and genetic distance between populations, which indicates a violation of the isolation model by distance and confirms the thesis put forward by us that the urbanized forest-steppe landscape disrupts the natural migration processes, leads to the strong isolation and the genetic drift in the snail populations. At the same time, the phenomenon of increasing the degree of division of the populations against the background of reduced the allelic diversity, noted by us in many groups of bush snails, can be regarded as a shift in genetic equilibrium towards an increase in the interpopupulation diversity (according to the Wright model). The revealed absence of the effect of isolation by distance can be a consequence of the action of the stabilizing natural selection. The assumption of the dependence of the esterase alleles frequencies in the bush snail populations on the genetic (biochemical) characteristics of the food objects was proposed. The effective size, calculated using the Slatkin formula turned out to be comparable with the background, adventive and relict species of the terrestrial mollusks living in the study area (Ne = 2.27.6).

Обзор наземных моллюсков как промежуточных хозяев гельминтов и разнообразие последних

The purpose of the research is to analyze and synthesize literature data on terrestrial mollusks, intermediate hosts of helminthes vertebrat. Materials and methods. An analysis of the literature data on the distribution of helminths of vertebrates among species of terrestrial mollusks acting as their intermediate hosts was performed. Results and discussion. A literature review of helminth species found in terrestrial mollusks from different regions of the world and the Republic of Belarus is presented. A reasoned assumption has been put forward about more than 40 species of terrestrial mollusks of the Republic of Belarus as potential intermediate hosts of 30 or more species of helminths.

The impact of the Gabčíkovo hydroelectric power barrier on the Danube floodplain environment-the results of long-term monitoring of land snail fauna.

The Gabčíkovo Water Project, a major construction of damming and canalizing on the upper part of the middle Danube, significantly changed hydrological regime of the Danube inland delta, destroyed or affected most of the 230km2 of wetlands and directly disrupted the original and unique ecosystem along a 37km long river stretch. The aim of this study was to describe the effect of the Gabčíkovo Waterworks on the taxonomical and functional structure of the molluscan assemblages in the Danube riparian floodplain forests. The results demonstrate that the Gabčíkovo Waterworks had a direct and long-lasting effect on the direction of the succession of terrestrial molluscan assemblages, especially in the area of the by-pass section. The changes in the soil moisture caused by the waterworks' operation led to significant changes in the species and functional composition of these assemblages. More specifically, however, the proportion of the generalists which prefer dry biotopes increased, while the number of moisture-demanding species decreased. Our results indicate that the current artificial flooding system cannot fully replace previous natural floods in the Danube inland delta, and it is also insufficient for restoration and preservation of the humidity conditions in the softwood floodplain forests which would be similar to the pre-operation period of the Gabčíkovo Waterworks.

Fitting Competing Models of the Population Abundance Distribution: Land Snails from Nikopol Manganese Ore Basin Technosols

Abstract This paper examines the temporal dynamics of terrestrial mollusks of the Nikopol manganese ore basin technosols. The research was carried out at the Research Centre of the Dnipro Agrarian and Economic University in Pokrov (Ukraine). Sampling was carried out in 2012–2014 on four variants of artificial soil: formed on red-brown clays, on loess-like loams, on gray-green clays, and on humus-rich layer. The distribution of the number of individuals in a mollusk population was described by broken stick, Motomura, log-normal, Zipf, and Zipf-Mandelbrot models. It was shown that the series of models that best describe mollusk abundance distribution is specific for a particular species and technosols type and generally is invariant over time.

The frictional and adhesive properties of the shells of terrestrial hairy snails

AbstractHair‐like structures of the shell in some terrestrial snails have been suggested to represent an adaptive advantage. One of the recently proposed explanations was the hypothesis that the possession of hairs facilitates the snails' adherence to the leaves of the plants during foraging, when humidity levels are high. In order to obtain some reliable data to test this contact mechanics hypothesis, the present paper deals with the frictional and adhesive properties of the smooth and hairy shells of two species of terrestrial mollusks, Trochulus hispidus and T. villosulus. Additionally, actively generated traction force of the snails was measured on different substrates. The conducted experiments revealed that in wet conditions the hairiness indeed increases friction and that adhesion through the water film is high enough to retain the weight of the snail. However, possession of long hairs decreases the adhesion, in comparison with the animals with short hairs. Our data suggest that hair‐like structures require more energy expenditure during locomotion and only provide the advantage of higher adhesion on wet substrates. Obtained maximal traction forces were about 30 times higher than friction forces of the shell surface dragged over the substrate. Neither wetting condition of the substrate nor surface roughness had considerable effect on the traction forces of snails. Therefore, the function of the hair‐like structures seems not to be related with snail locomotion and adhesion.

Heterogeneous composition of anthropogenic litter recorded in nests of Yellow-legged gull (Larus michahellis) from a small Mediterranean island.

This note reports data about a heterogeneous assemblage of anthropogenic litter recorded in 307 nesting and roosting sites of Yellow-legged Gull (Larus michahellis) from a small Mediterranean island. I obtained items of anthropogenic litter on > 30% on the total, with plastic, glass and paper the significantly more abundant litter categories. Litter items were found in the nests mainly as a dry remnant in the regurgitated pellets. Fragments of expanded polystyrene (EPS) with peck marks were also recorded, these last transported to the nests because of their resemblance to the cuttlebones of the Sepia cuttlefish. Ingestion of this litter and the pecking on EPS can negatively impact on seabirds. Moreover, the presence of this litter highlights a transport of polluting material even at considerable distance from anthropized areas. Finally, the presence of scavenger species (an endemic lizard and terrestrial molluscs) feeding on food remains could suggest an assimilation of litter into the trophic webs.

Marine and terrestrial molluscs in the sanctuary. The molluscan remains from the 2003–2004 excavations in the Sanctuary of Poseidon at Kalaureia

This paper presents the hand-collected molluscan remains that were recovered from the excavations in Areas C and D of the Sanctuary of Poseidon at Kalaureia, Poros, in the years 2003–2004. The paper aims at the presentation of the finds and at using the molluscan biological and ethological traits to provide insights into the possible capture methods and use. Land snails are also summarily presented.

Possible egg masses from amphibians, gastropods, and insects in mid-Cretaceous Burmese amber

ABSTRACT The eggs of fish, amphibians, and many invertebrates are soft, delicate structures that are only rarely preserved in the fossil record. Here we report egg masses preserved as inclusions in mid-Cretaceous amber deposits of Myanmar. Of five specimens recovered, three of the egg masses probably pertain to insects, but the other two appear different. One mass is composed of relatively stiff eggs that retain their shape throughout the mass and may be linked by mucoid strands. This morphology resembles that of some terrestrial molluscs. The second mass is composed of softer eggs that have compressed one another so that their shapes are strongly distorted within the mass. These eggs most closely resemble those of amphibians. Given the forest environment reconstructed for the amber locality, the eggs were presumably attached on or close to the resin producing tree.

Geographical and chronological variability of the conchological characters of the mollusc <i>Fruticicola fruticum </i>(O.F.Müller, 1774) (Gastropoda; Pulmonata; Bradybaenidae) in the Eastern Europe

The population structure of the terrestrial mollusk (Gastropoda, Pulmonata, Bradybaenidae) in different landscapes of Eastern Europe on the basis of conchological measurements, including morphometric parameters and color variants was studied. For all morphometric parameters used, statistically significant differences were found between the studied populations. At the same time, the shell size are determined not by zonal characteristics, but by microbiotopic conditions. Changes in the frequency of shell phenotypes in Fr. fruticum populations are probably of a multifactorial nature. The ratio of different color variants can be caused by the influence of radiation, cyclic fluctuations of climatic factors, succession changes in biotopes, and gene drift.

The Ability of Terrestrial Mollusks of Moscow Oblast to Feed on Invasive Species of the Genus Solidago (S. canadensis and S. gigantea)

Invasive species have to overcome the biotic resistance of the environment for successful distribution in the secondary range; this resistance can be effectively made by unspecialized phytophages. We carried out a series of laboratory experiments on studying the ability of generalist phytophages, such as terrestrial mollusks, to feed on invasive goldenrod species (Solidago canadensis L. and S. gigantea Aiton). A significant number of terrestrial mollusks of six species were found on the stems and leaves of goldenrods; however, the results of laboratory experiments have shown that most of them cannot consume this plant as food, and Fruticicola fruticum (O.F. Muller) (Bradybaenidae) and Deroceras sp. (Agriolimacidae) do not choose goldenrod when there are other alternatives, although they can potentially feed on goldenrod. Therefore, snails and slugs in natural populations have a negligible effect on the vital activity of S. canadensis and S. gigantea and cannot suppress the expansion of these species.

A chromosomal-level genome assembly for the giant African snail Achatina fulica.

Background Achatina fulica, the giant African snail, is the largest terrestrial mollusk species. Owing to its voracious appetite, wide environmental adaptability, high growth rate, and reproductive capacity, it has become an invasive species across the world, mainly in Southeast Asia, Japan, the western Pacific islands, and China. This pest can damage agricultural crops and is an intermediate host of many parasites that can threaten human health. However, genomic information of A. fulica remains limited, hindering genetic and genomic studies for invasion control and management of the species.FindingsUsing a k-mer–based method, we estimated the A. fulica genome size to be 2.12 Gb, with a high repeat content up to 71%. Roughly 101.6 Gb genomic long-read data of A. fulica were generated from the Pacific Biosciences sequencing platform and assembled to produce a first A. fulica genome of 1.85 Gb with a contig N50 length of 726 kb. Using contact information from the Hi-C sequencing data, we successfully anchored 99.32% contig sequences into 31 chromosomes, leading to the final contig and scaffold N50 length of 721 kb and 59.6 Mb, respectively. The continuity, completeness, and accuracy were evaluated by genome comparison with other mollusk genomes, BUSCO assessment, and genomic read mapping. A total of 23,726 protein-coding genes were predicted from the assembled genome, among which 96.34% of the genes were functionally annotated. The phylogenetic analysis using whole-genome protein-coding genes revealed that A. fulica separated from a common ancestor with Biomphalaria glabrata ∼182 million years ago.ConclusionTo our knowledge, the A. fulica genome is the first terrestrial mollusk genome published to date. The chromosome sequence of A. fulica will provide the research community with a valuable resource for population genetics and environmental adaptation studies for the species, as well as investigations of the chromosome-level of evolution within mollusks.

Fungal volatile organic compounds show promise as potent molluscicides.

BACKGROUNDSlugs and snails constitute major crop pests. Withdrawal of metaldehyde has prompted a search for more environmentally friendly yet fast acting molluscicides. This study investigated the response of representative molluscs to conidia and volatile organic compounds (VOCs) of the insect pathogenic fungus Metarhizium brunneum Petch.RESULTSConidia of M. brunneum had antifeedant/repellent properties with repellency being dependent upon the fungal strain and conidia concentration. Three commonly produced fungal VOCs, 1‐octene, 3‐octanone and 1‐octen‐3‐ol, were repellent at low doses (1–5 μL) but could kill slugs and snails on contact or fumigation. At the highest dose tested (10 μL), 100% mortality was achieved for Cornu aspersum Muller (garden snail) and Derocerus reticulatum Muller (grey field slug) within 1 h post‐treatment with the first deaths being recorded in <11 min. Aqueous formulations (20% v/v) of the most potent VOCs, 3‐octanone and 1‐octen‐3‐ol, could be sprayed onto plants to kill or drive the pest of the crop with no phytotoxic effects.CONCLUSIONThe sensitivity of terrestrial molluscs to 3‐octanone and 1‐octen‐3‐ol and the ephemeral nature of these compounds makes these excellent candidates for development as mollusc repellents or molluscicides. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

GROUP OF GASTROCOPTA EDLAUERI (WENZ, 1921) – GASTROCOPTA CONTRACTA (SAY, 1872) (MOLLUSCA, PULMONATA) FROM THE CENOZOIC OF EURASIA

The comprehensive study of fossil gastropods of the G. edlaueri (Wenz, 1921) – G. contracta (Say, 1872) group from the Oligocene sediments of Mongolia, the Miocene sediments of Tuva, as well as the Neogene ones of Ukraine and Poland is presented. The Gastrocopta species of this group are considered as rather of North American than Central Asian origin. The study shows that the intraspecies categories only can be distinguished within the Gastrocopta edlaueri which demonstrates wide shell variability. A reliable study of accompanying samples of terrestrial mollusks along the collecting of fossil mammals requires the participation of malacologists to provide a complete picture of mollusk fauna of the investigated localities. The variability of G. edlaueri (Wenz, 1921) in time and space was studied in detail. It was shown that there is no sufficient basis for isolating a new species of G. polonica.

Bionomics of the slug-parasitic nematode Alloionema appendiculatum and its effect on the invasive pest slug Arion vulgaris

Alloionema appendiculatum Schneider, 1859 (Rhabditida: Alloionematidae) is a common parasite of terrestrial molluscs capable of causing high snail mortality in heliculture. It has also been described as a parasite of the invasive slug Arion vulgaris Moquin-Tandon, 1855 (Pulmonata: Arionidae), a serious pest in central Europe. Nontheless, our knowledge about the ecology of this nematode is poor. Our study aims to provide new information about some as yet unknown aspects of the biology of this species, mainly its prevalence, attraction to slug associated cues, development, progeny production, and influence on the mortality and feeding activity of its host. The results of our study provide new information about the saprobic life cycle and natural prevalence of the species, but also show that, in standard conditions, A. appendiculatum has a very weak influence on the mortality and feeding activity of A. vulgaris. We concede that the effect of A. appendiculatum on the slug host can be strongly influenced by bacterial associates, even though the role of bacteria in nematode development is questionable and needs further research. Based on our results, A. appendiculatum does not seem to be a suitable agent for the biocontrol of A. vulgaris.

Порівняльна оцінка особливостей екологічних ніш наземних молюсків у різних типах техноземів Нікопольського марганцеворудного басейну

Порівняльна оцінка особливостей екологічних ніш наземних молюсків у різних типах техноземів Нікопольського марганцеворудного басейну

Стійкість угруповань молюсків техноземів Нікопольського марганцеворудного басейну

The regularities of the stability of terrestrial molluscs community in the Lyapunov sense that there in artificial soil-like structures within the Nikopol manganese ore basin, namely pedozems and sod-lithogenic soils on red-brown clay, gray-green clay and loess. The studies were conducted during the 2012-2014 biennium. on site remediation of Nikopol manganese ore basin in Pokrov. The basis for describing the dynamics of communities are taken cascading Lotka-Volterra equations. It was established that between the number of species there is a positive correlation between the presence of which can be attributed to common features of ecology of terrestrial molluscs in general. The nature of interspecies relationships has its own specificity, depending on the type of biogeocoenosis. The study found the most sustainable communities of terrestrial molluscs are formed on the sod-lithogenic soils on loess loam and least stable - on sod-lithogenic soils to gray-green clays and pedozems. For sod-lithogenic soils found the biggest off-season difference of sustainability indicators. The most sustainable communities in the spring and summer, and the least stable - in the summer-autumn period. Most regular factor in the sustainability of communities is negative autocorrelation kinds of communities, most often it is the dominant form of B. cylindrica. Interspecific interactions have both stabilizing and destabilizing effect, which is the specificity of each type of community dynamics tehnozems. A promising area of research can be considered as an assessment of the functional role of terrestrial molluscs community structure mezopedobionts tehnozems. The knowledge of the dynamics of terrestrial molluscs community will help address issues of management functional properties rekultozems models.

Особливості екологічної ніші молюска Monacha (Monacha) cartusiana (O. F. Muller, 1774) у техноземі на сіро-зеленій глині (Нікопольський марганцеворудний басейн)

У роботі встановлено особливосто екологічної ніші молюска Monacha (Monacha) cartusiana (O. F. Muller, 1774) у техноземі на сіро-зеленій глині (Нікопольський марганцеворудний басейн) та показано стаціонарність у часі одержаного результату. Дослідження проводили протягом 2012–2014 рр. на ділянці рекультивації Нікопольського марганцеворудного басейну в м. Покров. Як екогеографічні предиктори екологічної ніші молюсків виміряно такі показники, як електропровідність ґрунту, агрегатний склад, твердість ґрунту на глибині до 0,5 м, проективне покриття фізіономічних типів рослинності та фітоіндикаційні оцінки екологічних режимів. Для кількісної характеристики екологічної ніші застосовано ENFA-аналіз. У результаті дослідження встановлено, що маргінальність екологічної ніші M. cartusiana визначають такі екогеографічні предиктори, як уміст агрегатів розміром 1–2 та 2–3 мм (позитивна маргінальність) і &gt; 10 мм (негативна маргінальність), твердість ґрунту на глибинні 0–5, 20–25 та 35–40 см і фізіономічний вигляд рослинного покриву. Цей вид надає перевагу ділянкам із більшим проективним покриттям фізіономічного типу ІІІ та уникає ділянок із переважанням фізіономічного типу V і VI. Надають перевагу ділянкам із підвищеною аерацією ґрунту. Спеціалізацію екологічної ніші M. cartusiana визначають такі екогеографічні предиктори, як уміст агрегатів розміром 0,5–1,0 та &gt; 10 мм, твердість на різних глибинах, електрична провідність ґрунту, кріоклімат і континентальність, проективне покриття фізіономічних типів ІІІ та VI. Установлені особливості екологічної ніші є стаціонарними за період досліджень.

Dispersers are more likely to follow mucus trails in the land snail Cornu aspersum.

Dispersal, movement leading to gene flow, is a fundamental but costly life history trait. The use of indirect social information may help mitigate these costs, yet we often know little about the proximate sources of such information, and how dispersers and residents may differ in their information use. Terrestrial molluscs, which have a high cost of movement and obligatorily leave information potentially exploitable by conspecifics during movement (through mucus trails), are a good model to investigate links between dispersal costs and information use. We studied whether dispersers and residents differed in their trail-following propensity in the snail Cornu aspersum. Dispersers followed mucus trails more frequently than expected by chance, contrary to non-dispersers. Trail-following by dispersers may reduce dispersal costs by reducing energy expenditure and helping snails find existing habitat or resource patches. Finally, we point that ignoring the potential for collective dispersal provided by trail-following may hinder our understanding of the demographic and genetic consequences of dispersal.

New type of terrestrial mollusc of Archaica (Gastropoda, Pulmonata, Hygromiidae) from Central Asia

A new species of land mollusk of the genus Archaica (Gastropoda, Pulmonata, Hygromiidae) from Central Asia A. Pazilov, Z. Kudratov, Z. Makhmudzhonov - New species - differs in relatively thin-walled slightly translucent shell, not more than 4.5 well convex, slowly growing turns.

INTERNAL-POPULATION PROPERTIES OF HELIX ALBESCENS SHELLS IN THE NORTHWEST AZOV

A comparative analysis of the clonic features of the Helix albescens terrestrial molluscs collected in the natural and anthropogenic biotopes of the northwest Azov in 2017-2018 is carried out. Samples were taken from 10 habitats of molluscs living within the borders of Melitopol and the region. In total 1325 specimens of shells of H. albescens were collected. The results of studying the interpopulation and intrapopulation variability of Helix albescens in shell height (SH), large diameter (LD), small diameter (SD), mouth height (MH), mouth width (MW). The area of the mouth (S), the conditional volume (V), the relative height of the mouth, the shape of the mouth and a number of indices were calculated. Trees and bushes vegetation was dominated on the most points of collecting material. The connection between morphometric features of mollusc shells and biotopic peculiarities of their habitation is revealed. The average variability of the shell size in the most of the samples is found, the value of Cv is between 10 and 20%. The lowest coefficient values of variation among the 14 samples were recorded for such parameter as height of the mouth. Comparison of shells Helix albescens sizes from territories with different anthropogenic loading showed that in the city the shells are bigger than in the countryside. The maximum sizes of shells had molluscs, which were collected within the area of Melitopol at points located in biotopes with multistory buildings, private sector and gardens, the smallest - at points located outside the city. Correlation analysis showed a high level of correlation dependencies for all shell parameters. The main morphometric molluscs’ shell indices have changed in wider ranges, which indicates a high variability. But in general, the relevant indicators are at the average level indicated for these species within the range.