Temporal and directional patterns of nymphal Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) movement on the trunk of selected wild and fruit tree hosts

Halyomorpha halys Stål (Hemiptera: Pentatomidae) is an invasive and highly polyphagous pest in Mid-Atlantic tree fruit orchards. Both nymphs and adults feed on and injure fruit. Many of its wild tree hosts (e.g. Ailanthus altissima) are common and abundant in the woodlands that often border orchards and are thought to increase localized H. halys densities and pest pressure season-long. Halyomorpha halys nymphs have a substantial dispersal capacity by walking and their developmental rate and survivorship are enhanced by feeding on multiple hosts. Their seasonal patterns of upward and downward movement on the trunks of several known host trees at the woodland-orchard interface were monitored using passive traps. “Up” and “down” traps were installed on apple and peach trees in border rows next to woods and on wild tree hosts at the woods edge at three apple and two peach sites in 2014 and 2015. Captures were recorded weekly and compared among host trees across the season. In 2014, more nymphs were intercepted while walking up than down and captures of upward and downward walking nymphs varied significantly among the hosts. All of the dispersive nymphal instars were captured and captures reflected seasonal changes in instar distribution, but overall, most captures were of second instars.  Results are discussed in relation to host and seasonal effects on the movements of H. halys nymphs at the orchard-woodland interface.