Soil moisture and soil type influence the breeding behavior of the pest snail Cernuella virgata (da Costa)

The common white snail (Cernuella virgata) (da Costa) is an exotic pest of grain crops in southern Australia. In order to better control these snails and develop optimal management strategies, it is important to understand how their breeding behavior is influenced by soil moisture and soil type. Pairs of adult snails were placed into vials containing either a calcareous or a non-calcareous soil at five moisture levels along their soil moisture retention curves: no-water; permanent wilting-point; mid-point; field-capacity; and saturation. Survival analysis was used to estimate the tendency of C. virgata to lay an egg cluster. ANOVA showed that there was no two-way interaction between soil moisture and soil type, however, one-way ANOVA showed that the tendency of C. virgata to deposit the first egg cluster was greater in the non-calcareous soil and increased as soil moisture increased. There was a higher total number of egg clusters laid in the non-calcareous soil. The total number of egg clusters laid in the two soil types increased as soil moisture content increased. No eggs were laid in the no-water treatment. C. virgata breed more frequently in moist soils, and egg laying is greater in wet seasons. Therefore the risk of grain contamination in spring is predicted to be greater following a relatively wet autumn and spring.