Vertical Sampling in Tree Canopies for Halyomorpha halys (Hemiptera: Pentatomidae) Life Stages and its Egg Parasitoid, Trissolcus japonicus (Hymenoptera: Scelionidae)

Abstract

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an invasive agricultural and nuisance pest that has established across much of the United States and caused significant crop losses in the Mid-Atlantic region. While it has been monitored extensively using ground-deployed pheromone traps, the vertical distribution of its life stages in the canopy of wild tree hosts has not been examined. In Virginia, small pyramid traps baited with 'low-dose' H. halys pheromone lures were deployed via a pulley system at the lower, mid-, and upper canopy of female tree of heaven (Ailanthus altissima (Mill.) Swingle) in 2016 and 2017 and male A. altissima and hackberry (Celtis occidentalis L.) in 2017. Weekly captures of adults and nymphs were recorded throughout each season. Each year, additional female A. altissima trees were felled during the two main periods of H. halys oviposition. The number and relative locations of all pentatomid egg masses found on foliage were recorded and any parasitoids that emerged from them were identified. Halyomorpha halys adults and nymphs were captured in greatest numbers in upper canopy traps and in lowest numbers in traps near the tree base. More H. halys egg masses were collected from mid-canopy than from the lower or upper canopy. The adventive egg parasitoid, Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), emerged most frequently from egg masses found at mid-canopy and was not recovered from those in the lower canopy. Results are discussed in relation to the foraging ecology of H. halys and its natural enemies, including TT. japonicus.

Establishment in an Introduced Range: Dispersal Capacity and Winter Survival of Trissolcus japonicus, an Adventive Egg Parasitoid

“…Platygastrid parasitism rates also average below 10% in other orchard crops [29,58]. By restricting sentinel egg or yellow card placement at heights below 1.8 m, we may underestimate parasitism rates, which are highest in the mid-canopy, at heights of approximately 4.3 m [59]. Equipment to detect wasps at heights above head level may be necessary for better interpretation of T. japonicus dispersal in orchard crops.…”

Sampling Methods for Adventive Trissolcus japonicus (Hymenoptera: Scelionidae) in a Wild Tree Host of Halyomorpha halys (Hemiptera: Pentatomidae)

“…Backfolding sticky traps deployed in the middle canopy of 10 trees over 3 wk in 2017 yielded 12 T. japonicus (0.4 ± 0.36 SE per trap), 11 of which were on one trap. Quinn et al (2019) reported that naturally laid H. halys egg masses parasitized by T. japonicus were found only in the middle and upper thirds of the canopy of felled female tree of heaven. Although relatively few T. japonicus were detected during the present studies, which was not unexpected given that it is likely in early stages of establishment, the distribution of its detections in the tree canopy via vertical transects of sentinel H. halys egg masses and yellow sticky traps paralleled those from our previous research.…”

“…Five female tree of heaven growing at the woods edge next to fruit orchards in Frederick County, VA, were used for sampling in 2016 and 2017. As described previously (Quinn et al 2019), an eyebolt was inserted near the top and bottom of the trunk of each tree, and a pulley system created by running a rope through these and attaching the ends enabled sampling devices to be attached to the rope and spaced evenly along the trunk at lower, middle, and upper canopy locations.…”

“…Scouting for naturally laid eggs and deployment of sentinels has usually involved sampling from the ground (Abram et al 2017). However, Quinn et al (2019) found that most H. halys egg masses were in the middle and upper tree canopies of tree of heaven, Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae), and that those parasitized by T. japonicus were exclusively from the middle and upper tree canopies, suggesting that sampling from the ground may reduce the likelihood of T. japonicus detection.…”

Trapping for early detection of the brown marmorated stink bug, <i>Halyomorpha halys</i>, in New Zealand

“…To address this, research that monitors endemic stink bug populations in and around production systems (rather than invasive species around transitional facilities) will help to validate the findings presented here. Trap placement within the canopy significantly affects BMSB catch (Quinn et al 2019) and other placement factors (e.g. in orchard versus in hedgerows, or within native versus non-native hosts) may be similarly important.…”