Distribution and population genetic analysis of lymnaeid snails in Aomori prefecture, Japan

Fasciolosis, a parasitic disease caused by Fasciola flukes, leads to economic losses in livestock. These flukes require freshwater snails, such as the genera Orientogalba and Galba as intermediate hosts, made snail distribution monitoring essential for disease surveillance and prevention. A survey conducted in Aomori prefecture from spring 2022 to summer 2023 identified Orientogalba snails and Galba snails in 49 rice paddies. Molecular analysis of 233 cytochrome c oxidase subunit 1 partial sequences classified Orientogalba into O. hokkaidoensis and O. ollula. Orientogalba hokkaidoensis was widely distributed across Aomori prefecture. Most Galba snails were identified as Galba pacifica. Additionally, some Lymnaea schirazensis-like snails were detected. These findings provide fundamental data on freshwater snails in Aomori, aiding fasciolosis control.