Intensity of parasitic mite infection decreases with hibernation duration of the host snail

Abstract

SUMMARYTemperature can be a limiting factor on parasite development.Riccardoella limacum, a haematophagous mite, lives in the mantle cavity of helicid land snails. The prevalence of infection byR. limacumin populations of the land snailArianta arbustorumis highly variable (0–78%) in Switzerland. However, parasitic mites do not occur in host populations at altitudes of 1290 m or higher. It has been hypothesized that the host's hibernation period might be too long at high elevations for mites and their eggs to survive. To test this hypothesis, we experimentally infected snails and allowed them to hibernate at 4°C for periods of 4–7 months. Winter survival of host snails was negatively affected byR. limacum. The intensity of mite infection decreased with increasing hibernation duration. Another experiment with shorter recording intervals revealed that mites do not leave the host when it buries in the soil at the beginning of hibernation. The number of mites decreased after 24 days of hibernation, whereas the number of eggs attached to the lung tissue remained constant throughout hibernation. Thus,R. limacumsurvives the winter in the egg stage in the host. Low temperature at high altitudes may limit the occurrence ofR. limacum.