Pheromone traps for Halyomorpha halys monitoring: evaluation of side-effects in fruit orchards

The brown marmorated stinkbug Halyomorpha halys (Stål) (Heteroptera, Pentatomidae) is an invasive polyphagous alien species detected in Italy for the first time in 2012, in the Modena province. By piercing and sucking on fruits and seeds, it causes damages that render products unmarketable. A few years following its discovery, it is reported as a key pest of fruit orchards all over Northern Italy and is presently threatening many agricultural crops in other invaded European countries. Currently, the monitoring of H. halys is performed using traps baited with specific aggregation pheromones combined with a synergist. The stinkbugs respond to the lures by aggregating both inside and outside the traps. The presence of individuals feeding actively in the area around the trap, with a consequent increase in fruit damages, represents a side-effect of this type of traps, which poses a strong limitation for their use in commercial fruit orchards. The aim of this study was to assess the range of side-effects around the traps in fruit orchards. A field experiment was performed in 2016-2017 to estimate the area around the traps potentially affected by the increase in fruit damage. A baited trap was installed in the first row of selected pear orchards at the beginning of May and the percentage of deformed fruits on adjacent plants was evaluated one week before harvest. The results show that fruit damage was particularly high on plants located within 4-5 m from the traps, while an acceptable level of damage was found on plants situated more than 10 m from the traps. These results provide fundamental information for the use of traps baited using aggregation pheromones in the field.