274 Invasive Stink Bugs and Related Species (Pentatomoidea)
4.6.3 Cultural Control
Cultural control tactics for Halyomorpha halys are being investigated but have not been implemented
in the United States to date. However, strategies have been reported from Asia although not widely
adopted. Lee et al. (2013a and references therein) reported that mechanical removal of eggs and nymphs
from crops has been considered. Other strategies proposed include destruction of nearby alternate hosts
and construction of overwintering traps. Bagging fruit also has been proposed in Asia (Funayama 2002)
although results were mixed. In the United States, bagging fruit also has been pursued in small-scale
studies against H. halys (Daniel L. Frank, unpublished data; see Acknowledgements). Trap cropping
also has been considered in Asia and the United States. To date, this tactic has only been evaluated in
limited experimental trials. However, progress has been reported by Nielsen et al. (2016b) in a multi-
state comparison trial that evaluated sunflower, grain sorghum, eggplant, pearl millet, and Admiral pea
as trap crops to protect bell peppers from H. halys and native stink bugs. At all sites, both sunflower and
sorghum hosted significantly higher seasonal populations of this bug. Importantly, there was a difference
in timing of attractiveness with sunflower having higher densities of H. halys than sorghum because the
sunflower variety flowered before the sorghum variety produced seed heads. Due to the long life cycle of
H. halys, and the need to protect crops, sunflower and sorghum biculture currently are being evaluated
as potential trap crops for this bug in organic systems to protect green peppers on organic farms. Olusola
(2016) examined the use of several potential crop plants and found cowpea (Early Scarlet) to be a suitable
trap crop. Mathews et al. (2017) has evaluated a polyculuture system composed of sorghum and sunflow-
ers as a combined trap crop in organic peppers. Their 2-year study showed that the trap crop was more
attractive to H. halys than peppers for a period of 8 weeks. However, the trap crop did not prevent adults
from entering the pepper crop at most sites, and the resulting reduction in damage would not make this
tactic economically viable. In a separate study involving the the same plant species, Blaauw et al. (2017)
used harmonic radar, immunomarking and visual sampling to evaluate movement of H. halys within and
between a polyculture planting of peppers, sorghum, and sunflowers. They demonstrated that immuno-
marking followed by dislodgement of individuals revealed higher densites in the trap crop compared to
visual sampling, and that very little movement of adults between the peppers and the trap crop occurred.
Harmonic tagging of adults also revealed that adults stayed longer in the trap crops and reduced their
movement when compared to individuals released into the peppers.
4.6.4 Biological Control
In the invaded ranges of the United States and Europe, populations of Halyomorpha halys are thought
to have been able to establish and increase, in some cases, to outbreak levels due in part to the enemy-
release hypothesis (i.e., H. halys individuals escaping natural enemies from their native range). However,
biological control is considered likely to be the long-term solution for this bug; the impact of predators,
pathogens, and parasites is self-sustaining and can occur at landscape levels (Leskey et al. 2012a) where
it is likely to be the only management option available for stink bug populations. Indeed, a number of
natural enemies present within the invaded areas have been documented in different habitats and crops.
Chewing and sucking predators reported to feed on the eggs, nymphs, and adults of Halyomorpha halys
in the United States include (but are not limited to) members of the Anthocoridae, Asilidae, Cantharidae,
Carabidae, Chrysopidae, Coccinellidae, Forficulidae, Geocoridae, Gryllidae, Mantidae, Melyridae,
Pentatomidae, Reduviidae and Tettigoniidae (Biddinger et al. 2012, Pote et al. 2015, Lara et al. 2016,
Morrison et al. 2016). Other predators include spiders, nest-provisioning sand wasps (Crabronidae), and
some gastropods (slugs) (Pote et al. 2015, Lara et al. 2016, Morrison et al. 2016, 2017c) and bats (Masslo et
al. 2017). Among predatory arthropod groups, differences in overall predation rates have been observed
in different years, geographic locations, and cropping systems (Rice et al. 2014). Chewing predators
were thought to be more important than piercing-sucking egg predators in a comparative multistate
study in organic crops (Ogburn et al. 2016). Combining laboratory observations of a range of potential
predators with direct field observations and sentinel egg masses (i.e., either live or previously frozen egg
masses obtained from laboratory colonies that are placed in the field to evaluate natural enemy activity)
in orchards and vegetables, Morrison et al. (2016) determined that the most effective predators of eggs