A 3-year survey was carried out to assess the impact of egg parasitoids on
Halyomorpha halys
in northern Italy. In total, 1826
H. halys
egg masses were collected in the 3 years, and parasitoid adults ...emerged from 12% of eggs in 2016 and 2017, and from 21% in 2018.
Anastatus bifasciatus
was the main species emerging from
H. halys
eggs at all sites and years, confirming its ability to develop on fresh
H. halys
eggs. Only a few adults of native scelionid species emerged:
Trissolcus kozlovi
(first record in Italy),
T. semistriatus
,
T. basalis
and
Telenomus turesis
. In addition, a few adults of the Nearctic hyperparasitoid
Acroclisoides solus
(first record in Europe) were obtained from
H. halys
eggs collected at different sites. In 2018, for the first time an adventive population of
Trissolcus japonicus
was also recorded at one site, where the parasitism rate by the parasitoid species complex was overall higher than in 2016 and 2017. An additional supplemental survey at other sites of northern Italy in 2018 revealed the presence of
T. japonicus
and
Trissolcus mitsukurii
. The distribution and abundance of
T. japonicus
,
T. mitsukurii
and
A. solus
should be further investigated. Their host range and their interaction with native egg parasitoids, especially with
A. bifasciatus
, should be also assessed to better understand their potential role in biological control of
H. halys.
