272 Invasive Stink Bugs and Related Species (Pentatomoidea)
untreated, allow populations to increase and persist (Anonymous 2015b, Lee et al. 2013a); these popu-
lations serve as a nearly constant reservoir for re-infestation of susceptible crops. Second, mobile life
stages of H. halys have strong dispersal capacities. Adults have been reported to fly over 100 m in less
than one minute in the field (Lee et al. 2013b) and greater than 2 km in less than a day under labora-
tory conditions (Wiman et al 2014, Lee et al. 2014a), whereas nymphs have been recorded to walk over
20 m in less than 6 hours (Lee et al. 2014a). This indicates that vulnerable crops located considerable
distances away from populations of this bug on wild unmanaged hosts can be at risk of damage. Finally,
overwintering populations are not only present in large numbers in human-made structures such as
homes and sheds (Inkley 2012), they also are present in the natural landscape in dead-standing trees
(Lee et al. 2014b). These well-concealed and unchecked populations are dispersed widely throughout the
landscape, likely emerging over several months in the spring (Tracy C. Leskey and J. Christopher Bergh,
unpublished data; see Acknowledgements). Therefore, the need for effective tools to manage this bug is
paramount in the face of the threat posed by this invasive species.
4.6.1 Monitoring Options
Because Halyomorpha halys is attracted to lights, landscape-level monitoring using blacklight traps
is invaluable for detecting its presence and flight activity (Figure 4.1F). Blacklight traps have docu-
mented peaks in flight activity of this bug near tree fruit and soybean crops (Nielsen and Hamilton
2009a; Nielsen et al. 2011, 2013) as well as its spread across New Jersey, with exponential increases in
populations detected annually based on data collected through 2011 (Nielsen et al. 2013). Changes in the
seasonal abundance of adult populations have been mapped effectively using blacklight trap captures to
provide growers with relative pest pressure of local populations (Nielsen et al. 2013). These same data
have been used in conjunction with additional biological information to establish factors associated with
spread of this bug across the landscape (Wallner et al. 2014). These data also have been used in combina-
tion with crowd source reports that examine the relationship between urban and agricultural situations
(Hahn et al. 2016).
A variety of pheromone-based monitoring traps for Halyomorpha halys and other pentatomids have
been developed (Adachi et al. 2007, Khrimian et al. 2008, Leskey et al. 2012d, Bae et al. 2017). On-farm
monitoring can be conducted effectively using “trunk-mimicking” baited black pyramid traps (Leskey
et al. 2012d). Indeed, the two-component male-produced aggregation pheromone, in a 3.5: 1 ratio of
3 S, 6 S, 7 R, 10 S)-10,11-epoxy-1-bisabolen-3-ol and (3R, 6 S, 7 R, 10 S)-10,11-epoxy-1-bisabolen-3-ol (Khrimian
et al. 2014), deployed in combination with the synergistic compound methyl (E,E,Z)-2,4,6-decatrienoate
(the pheromone of the Asian stink bug species Plauti stali), serves as an attractive and sensitive olfac-
tory stimulus for inclusion in traps for season-long monitoring (Weber et al. 2014, Morrison et al. 2017b).
Methyl (E,E,Z)-2,4,6-decatrienoate alone, however, though attractive to nymphs whenever present in the
field, is not attractive to adults until the late-season (Leskey et al. 2012d), thereby limiting the utility of
this attractant as a stand-alone stimulus throughout much of the growing season.
In trials conducted across the United States with varying population densities, black pyramid traps
baited with the aggregation pheromone and synergist (mentioned above) combination were deployed
between agricultural production and nearby wild, host habitats and served as sensitive monitoring tools
for the presence, abundance, and seasonal activity of nymphs and adults of Halyomorpha halys through-
out the year. Overwintered adults first were captured in traps in early April with captures peaking in
mid- to late-May. Nymphs routinely were detected in traps beginning in June though some captures were
reported earlier. The smallest and largest populations of both adults and nymphs were detected in the
early- and late-season, respectively (Leskey et al. 2015a). Trap sensitivity can be increased markedly by
increasing the dose of the aggregation pheromone deployed alone or in combination with methyl (E,E,Z)-
2,4,6-decatrienoate (Leskey et al. 2015b).
The purity of the aggregation pheromone itself is not critical. It is comprised of two stereoisomers of
a natural sesquiterpene with a bisabolane skeleton, existing in 16 stereoisomeric forms. Halyomorpha
halys is not only strongly attracted to pheromonal stereoisomers but also is moderately attracted to
some non-pheromonal stereoisomers. This signifies that these “unnatural” stereoisomers are sufficiently