264 Invasive Stink Bugs and Related Species (Pentatomoidea)
of that variation on current niche-filling methods using an ordination method, ENMs, and occurrence
records. They found that niche filling and expansion occurred in both North America and Europe (42.7%
niche unfilling and 0.0% expansion in North America; 80.5% niche unfilling and 28.0% expansion in
Europe), and that H. halys populations have invaded climatically novel regions in central Europe. They
also estimate that there are regions of North America and Europe that are climatically similar to those
of H. halys in its native range in Asia that are yet to be colonized.
These findings agree with those of Kriticos et al. (2017) who used CLIMEX bioclimatic niche model
to estimate the potential distribution of Halyomorpha halys. Their model also predicted the potential for
further spread in North America, especially in the the central and southern United States. In Europe,
the model predicted that H. halys could spread further but not in the Ireland, Estonia, Latvia, Lithuania,
Scandinavia, or the United Kingdom. It also predicts that in the Southern Hemisphere, areas with
Mediterreanean, moist tropical and subtropical and warm-temperate climates could be at substantial
risk for invasion.
4.5 Current Impacts
4.5.1 Halyomorpha halys in Asia
Halyomorpha halys has one to two generations per year in most regions of China, Korea, and Japan
(Watanabe 1980, Bae et al. 2007, Yu and Zhang 2007) although four to six generations per year seem to
be possible in southern China (Hoffman 1931). H. halys adults start overwintering in crevices under bark
or human-made structures such as sheds, barns, and houses from late September to November (Ueno and
Shoji 1978, Funayama 2012). Sometimes, high numbers of adults migrate into houses for overwintering
(Zhang et al. 1993, Funayama 2012). In mountainous areas in Japan, their migration can end as early as
mid-October (Saito et al. 1964, Watanabe et al. 1994).
After overwintering, adults leave overwintering sites during late March to mid-May (Watanabe et al.
1978, Wang and Wang 1988, Qin 1990, Zhang et al. 1993, Funayama 2012) when temperatures outside
exceed 10°C (Qin 1990). The first host plants the adults utilize after overwintering include Chinese
arborvitae (Lee et al. 2009), Chinese milk vetch (Bae et al. 2009), mulberry, elm, willow, and Chinese
scholar tree (Wang and Wang 1988). During late spring or early summer, they enter orchards or crop
areas to feed and reproduce on crops and surrounding vegetation.
Halyomorpha halys has a wide host range in Asia; a total of 106 host plants in 45 families have been
reported in a review by Lee et al. (2013a). Among these host plants, major economic losses from these
bugs occur on crops in the Fabaceae and Rosaceae. Minor, but frequent, damage by H. halys also has
been reported on vegetables, field crops, ornamentals, and medicinal plants. In addition, this bug can
serve as a vector of witches’-broom disease on paulownia, Paulownia tomentosa (Song et al. 2008),
causing extensive economic damage to the timber industry.
4.5.1.1 Ecology of Halyomorpha halys and Its Economic Damage Reported in Asia
4.5.1.1.1 Fruit
Halyomorpha halys was considered a secondary pest in Asia until the 1970s when outbreaks of this bug
began to be noticed (Qin 1990). Starting with a nationwide outbreak occurring in Japan in 1973 (Yanagi
and Hagihara 1980), H. halys became a major pest of fruit trees with repeated outbreaks in China, Japan,
and Korea (Ohira 2003, Zhang et al. 2007). So far, considerable feeding damage has been reported on
apple, peach, pear, persimmon and yuzu (Qin 1990, Fengjie et al. 1997, Funayama 2003, Kang et al.
2003, Lee et al. 2007). Other fruit crops attacked in Asia include plum, mandarin, and grape (Oda et
al. 1980). Adults do not damage new leaves but do cause severe damage to young and ripening fruits.
Damaged fruits generally turn brown, collapse, and abscise during the ripening period (Watanabe 1996).
One of the reasons that Halyomorpha halys is a key orchard pest in Asia is the complex and diverse
environment around and in the orchard. For example, intercropping with legumes and vegetables within
an apple, pear, and peach orchard is not rare, especially in Korea, and is used to maximize the use of