Plži Obory Hvězda, Petřína a Vyšehradu v Praze [Gastropods of the Hvězda Game Reserve, Petřín and Vyšehrad in Prague]

Mollusc fauna of three protected areas in the capital of the Czech Republic, Prague, was revised after 25 years (Hvězda Game Reserve, Petřín) or studied for the first time (Vyšehrad). In total, 56 molluscs species were found and the survival of endangered species Vertigo angustior and Nesovitrea petronella in the Hvězda Game Reserve was verified. Generally, some sensitive species in well-preserved localities are being replaced by weed species, including non-indigenous ones such as the invasive Arion vulgaris, and the southern element Monacha cartusiana. On the other hand, some woodland species such as Arianta arbustorum, Urticicola umbrosus, Eucobresia diaphana, Arion silvaticus and Lehmannia marginata apparently spread in Prague.

Analysis of the adventitious fauna of terrestrial molluscs in the centre of the Russian Plain

The terrestrial mollusc fauna of the central part of the Russian Plain has been analysed with respect to its species composition and the proportion of adventitious species. The classification of adventitious species follows that accepted in Russia. Considerable changes in the fauna took place in the period 2016–2020. Helix lucorum Linnaeus and Cornu aspersum (O. F. Müller) were added to the terrestrial malacofauna of the area. Within the last four years, Arion vulgaris Moquin-Tandon colonised anthropogenic habitats and its spread continues. Krynickillus melanocephalus Kaleniczenko, Arianta arbustorum (Linnaeus), and Helix pomatia Linnaeus are now firmly established in natural ecosystems. Populations of A. vulgaris, K. melanocephalus, and A. arbustorum have become so abundant that now they cause significant damage to agricultural crops. In both natural and anthropogenic habitats K. melanocephalus and A. arbustorum displace Succinea putris (Linnaeus), Deroceras laeve (O. F. Müller), D. sturanyi (Simroth), D. invadens Reise, Hutchinson, Schunack et Schlitt, 2011, D. agreste (Linnaeus), D. reticulatum (O. F. Müller), Fruticicola fruticum (O. F. Müller) and Euomphalia strigella (Draparnaud). Interactions between invasive species are discussed. The proportion of alien species in several European countries and in Central Asia is compared.

Water vole Arvicola amphibius (Linnaeus, 1758) (Arvicolidae) as an agent of biological control of a tree snail Arianta arbustorum (Linnaeus, 1758) (Mollusca, Gastropoda, Helicidae)

Древесная улитка Arianta arbustorum, в последние десятилетия распространившаяся в центре Русской равнины, стала опасным вредителем сельского хозяйства. Заселяя природные биотопы, она вытесняет аборигенные виды как растений, так и моллюсков. Эффективные меры борьбы с A. arbustorum не разработаны. Даётся оценка жизнедеятельности водяной полёвки Arvicola amphibius по отношению к древесной улитке. Плотность A. arbustorum в саду около нор водяной полёвки 2433 экз/м2, а на удалении 5 метров от нор - 5231 экз/м2. Разница статистически достоверна. Показано, что поедание водяной полёвкой древесных улиток локально снижает их плотность. Водяная полёвка выступает как природный агент биологического контроля A. arbustorum, поддерживающий видовое многообразие в природе. Установлено, что осенью 65% всех взрослых A. arbustorum закапываются в землю, и уже недоступны для поедания водяными полёвками. Кормовые запасы водяной полёвки на зиму из моркови и картофеля обнаружены в 45 м от ближайшего огорода. The Wood snail Arianta arbustorum, which in recent decades has spread in the center of the Russian Plain, has become a dangerous pest of agriculture. Settling natural biotopes, it crowds out indigenous species of both plants and mollusks. Effective control measures against A. arbustorum have not been developed. Here we assess the activity of the water vole Arvicola amphibius in relation to the Wood snail. The density of A. arbustorum in the garden near the water vole burrows is 2433 ind./m2, while at a distance of 5 meters from the burrows it becomes 5231 ind./ m2. The difference is statistically significant. Water vole eating wood snails locally reduce their density. Voles thus act as a natural biological control agent of A. arbustorum, preserving species diversity. In the fall around 65% of A. arbustorum adults burrow into the ground and are no longer available for water voles. Winter fodder stocks of a Water vole with carrots and potatoes were found 45 m from the nearest garden.

Première mention de l’hélice des bois (Arianta arbustorum) au Québec et mention anecdotique du petit-gris (Cornu aspersum)

De nombreux individus de l’hélice des bois (Arianta arbustorum) ont été observés à Boucherville en juin 2015 et en 2016 ainsi qu’à l’Île-des-Soeurs en juin 2016. Cela représente les premières mentions de cette espèce au Québec et surtout, celles de populations viables. En 2015, un petit-gris (Cornu aspersum) juvénile a également été trouvé dans une grappe de raisins de Californie qui provenait d’une épicerie de Sherbrooke. Ces deux espèces d’escargots exotiques sont originaires d’Europe. Elles ont été introduites ailleurs au Canada et ne semblent pas envahissantes. Cependant, un suivi serait nécessaire pour vérifier la survie à plus long terme des populations d’hélice des bois à Boucherville et à l’Île-des-Soeurs et valider la présence de cette espèce ailleurs au Québec.