Insights into the reproductive activity ofOmphiscola (Lymnaea) glabra(Gastropoda: Lymnaeidae) in relation to soil geology in Central France

Abstract

-Transplantations of Omphiscola glabra from granite to marl, or vice versa, between farms known for cases of fasciolosis have shown differences in the maximum shell height of adult snails. To determine whether these differences were due to parasitism, soil geology, or a combination of both factors, four snail populations living on marl or granite were investigated over 12 months to specify the characteristics of egglaying in spring, and to follow the shell growth of both snail generations. In both types of habitats, the number of egg-masses per adult snail and their size significantly decreased during the 7 weeks of snail egg-laying. During this period, each adult snail on marl laid a mean of 6.4 masses and 93.3 eggs. On granite, the mean values were 5.7 masses and 69.1 eggs, respectively. Two annual generations, the first in spring and the other in autumn, were noted in these habitats. The maximum shell height of adults was different: a mean of 19.8 and 20.5 mm on marl compared with 17.2 and 18.2 mm on granite. Soil geology thus plays a role in the egg-laying and shell growth of O. glabra.

Detection of habitats colonized by Omphiscola glabra (Gastropoda: Lymnaeidae) on acid soils using indicator plants

“…Conversely, the more aquatic behaviour of O. glabra would require it to live in deeper water collections than G. truncatula and to undergo greater predation with aquatic predators. This will result in lower densities of O. glabra in its habitats, even though the masses laid by this species are more numerous and contain more eggs than those of G. truncatula (Vareille-Morel et al, 1998;Titi et al, 2017).…”