Monitoring of the invasive Halyomorpha halys, a new key pest of fruit orchards in northern Italy

Halyomorpha halys is an invasive polyphagous pest with a high negative impact on fruit orchards and other agricultural crops in the USA. In Italy, it was first detected in 2012 in Emilia Romagna, a northern region that is among the major European tree fruit production areas. A specific monitoring programme using active techniques was carried out in pear orchards and adjacent uncultivated areas between 2014 and 2016 to assess the abundance, seasonality and impact of H. halys and other phytophagous Heteroptera in the field. It emerged that just a few years after first discovery, this invasive species already largely outnumbers all the other Heteroptera and that it is a season-long pest for pear crops. Severe yield losses are reported in different farms, especially on the orchard borders, with more than 50% deformed fruits. Mirids are mostly found in the grassy areas and crops, and the other phytophagous Heteroptera, only occasionally detected in the orchard trees, occur mainly on hedges and other crops. Our survey demonstrates for the first time the great damaging potential of H. halys as a new key pest of orchards in southern Europe. The study also identified the patterns of seasonal abundance of adults and nymphs in the orchards and their uncultivated surroundings, providing baseline data for the development of specific strategies for sustainable management.