Long-term relationships between the abundance of pest molluscs and weather in agricultural fields in South Australia

ABSTRACT Invasive snails, Cernuella virgata, Theba pisana and Cochlicella acuta, infest grain crops prior to harvest in early summer southern Australia. They breed autumn–early winter peak abundance spring following the recruitment of young snails. Long-term studies (20 years) were established on three farms South Australia (two practicing pasture–cereal rotations one continuous cropping) better understand role prevailing weather driving population dynamics snail species develop predictive models that might assist farmers off-farm handlers anticipate future peaks tailor their management practices accordingly. The are asynchronous dynamics; they numbers different years. C. virgata late (preharvest) was most closely associated with, could be broadly predicted by, previous autumn rainfall, but no significant associations found between rainfall acuta T. pisana. Local air temperatures had little apparent association with all species. Broader scale weather, exemplified by El Niño Southern Oscillation Index, only occasionally, weakly, related virgata.