Effect of landscape composition on the invasive pest Halyomorpha halys in fruit orchards

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), native to eastern Asia, has become one of the most serious pests of fruit orchards worldwide. This invasive species is highly polyphagous and capable of moving across the agricultural matrix at long distances. However, comprehensive studies exploring how landscape characteristics influence H. halys colonization of orchards are still lacking. Here, we investigated the impact of landscape composition on the trap captures of H. halys in 113 orchards of different fruit tree crops (i.e., apple, pear, peach, walnut and kiwi) in northern Italy. We found that landscapes rich in semi-natural habitats and vineyards and poor in annual crops supported a higher abundance of H. halys juveniles in traps. This pattern became more evident towards the end of the growing season as the abundance of juveniles increased. Adults were instead not affected by the landscape. The invasive stink bug best responded to landscape processes at large spatial scales (3000 m) confirming its high dispersal ability. Moreover, H. halys did not display a strong preference among fruit orchards, although fewer individuals were caught in walnut orchards. Our findings suggest that the habitat composition of agricultural landscapes is a key factor driving the dynamics of this pest in agroecosystems and that semi-natural habitats might be important in supporting H. halys populations and crop colonization. These effects are however limited to juveniles while adult density was similar even in landscapes with very contrasting structures.