Area‐wide monitoring of potato tuberworm (Phthorimaea operculella) by pheromone trapping in Northern Italy: phenology, spatial distribution and relationships between catches and tuber damage

The potato tuberworm (PTW) Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) is key pest of potato in tropical and subtropical regions. From 2002 onward, PTW has emerged as a problem in the Bologna province, the main potato production area in Northern Italy. Field investigations were performed to study the temporal and spatial dynamics of PTW. Adult moths were monitored using pheromone‐baited traps over 3 years (2009–2011). Traps were georeferenced and catches were analyzed by geostatistical maps. Each year, the percentage of damaged tubers at harvest was assessed. Pheromone trapping, integrated with temperature‐dependent developmental times, showed that PTW completed two generations throughout the potato‐growing season; the remaining generations developed in the noncrop season. Maps showed a clumped distribution of PTW at the landscape scale. The hot spots of infestation corresponded to the areas most intensively cropped with potato. Trap catches from hilling to harvesting were linearly and positively correlated with the percentage of damage in 2 out of 3 years and in the pooled data set. The present study demonstrated the widening of PTW areal to Northern Italy. In this area, georeferenced pheromone traps were validated as a useful monitoring technique for describing the phenology and distribution of PTW, thus providing crucial knowledge for the rational management of this pest.