Abstract
We examined relationship between environmental factors and the density of a fleshwater snail, Semisulcospira libertina, which is main prey of a Genji firefly (Luciola cruciata) lavae at seven stations in Kawata River, Misato, Tokushima Prefecture. Moreover, we examined correlation between fleshwater snail density and observed number of Genji firefly. The results showed that the density of fleshwater snail was high on lentic site and positively correlated with water depth and rock size, while negatively correlated with the current velocity. River characteristics such as lentic, deep, and rocky substrate might be suitable for fleshwater snail habitat. Estimated densities of S. libertina were strongly correlated with the observed numbers of adult Genji firefly. To conserve Genji firefly, conservation of river environments for fleshwater snail habitats are also required.
