Following its first detection,
Halyomorpha halys
has become a key pest in many crops in NW Italy. In this area, one of the most important crops is hazelnut, in which the species can cause severe ...damage through feeding on nuts. Therefore, semi-field trials were carried out in NW Italy to compare the harmfulness of
H. halys
with that of the local hazelnut bug species, such as
Gonocerus acuteangulatus
,
Nezara viridula
, and
Palomena prasina
. Additionally, a 2-year field survey was conducted in hazel groves in NW Italy and W Georgia, another important hazelnut cropping area, to assess the presence and abundance of the new invasive species and to evaluate the damage at harvest. Monitoring was carried out by plant beating and by commercial traps throughout the growing season. In semi-field trials,
H. halys
was the most harmful species, causing the highest damage in kernels, and was able to survive and reproduce at higher rates. During field surveys in NW Italy,
H. halys
was sampled in groves late in the season in 2015 and, with higher populations, throughout the season in 2016. In W Georgia, bug population levels consistently increased in the 2-year period, resulting in a significant increase in damage at harvest in 2016. A similar trend is hence expected also in NW Italy in the following years. Moreover, data on individuals collected in different points of the hazelnut groves confirmed the border-driven behavior of this pest, leading to consideration of potential integrated pest management solutions.
The brown marmorated stink bug,
Halyomorpha halys
, native to East Asia, is an invasive alien pest that arrived in Europe in the early 2000s and poses an imminent threat to a wide variety of crops. ...Adventive populations of the Asian egg parasitoid
Trissolcus japonicus
, the most promising agent for classical biological control of
H. halys
, have recently been detected in Italy and Switzerland. Its prospective fundamental host range in Europe was evaluated in behavioural no-choice tests, followed by large-arena choice tests presenting host plants with naturally laid egg masses of target and non-target hosts. Developmental suitability of European non-target host species for
T. japonicus
was demonstrated, via no-choice tests, by offspring emergence (successful parasitism) from eleven out of thirteen non-target species tested (85%). Whereas successful parasitism of most non-target species was significantly lower, acceptance of
Arma custos
,
Palomena prasina
,
Pentatoma rufipes,
and
Rhaphigaster nebulosa
was not significantly different from
H. halys
controls. When eggs of
H. halys
and non-target species were exposed in a semi-natural situation in large-arena choice tests, the degree of non-target parasitism was substantially reduced for three out of four tested species, whereas parasitism of
Pa. prasina
eggs was not. It remains unclear if there are behavioural barriers to parasitism that may exist and preclude excessive parasitism of potentially threatened species in the field, but field data from the invaded areas in Switzerland and Italy could contribute to a risk–benefit evaluation of releasing or re-locating adventive
T. japonicus
populations into other parts of Europe.
The invasion of Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) has caused severe economic damage in crops in North America and Europe, motivating research to identify its natural enemies, both in ...native and invaded areas. In its Asian native range, the main natural enemies are egg parasitoids, among which the most effective are Trissolcus japonicus (Ashmead) and Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae) in China and Japan, respectively. In Europe, biology, host range, and impact of most native scelionid species are not well‐known. The present study aimed to investigate (1) presence and abundance of scelionid species that parasitize native Pentatomidae and Scutelleridae eggs in Northwest Italy, and (2) their ability to develop on H. halys eggs. During 4‐year field surveys, egg masses were collected and reared until bug nymph or adult parasitoid emergence. Then, the obtained scelionid females were tested for their ability to parasitize H. halys eggs in laboratory no‐choice experiments. Egg masses of all collected bug species were parasitized, and Telenomus spp. (Hymenoptera: Scelionidae), Trissolcus belenus (Walker), and Anastatus bifasciatus (Geoffroy) (Hymenoptera: Eupelmidae) were the most common parasitoids. In the laboratory, Trissolcus kozlovi Rjachovskij was the only species to significantly produce offspring from fresh H. halys eggs, whereas all tested Trissolcus species significantly induced host egg abortion (non‐reproductive effects). This study provides knowledge of the parasitoid species associated with native bugs, and represents a starting point to investigate the intricate interactions between native and exotic parasitoids recently found in northern Italy. These egg parasitoids could potentially be effective biocontrol agents of H. halys.
A 4‐year field survey revealed the presence of Scelionidae and Eupelmidae (both Hymenoptera) egg parasitoids in egg masses of native Pentatomidae and Scutelleridae (both Hemiptera) in Northwest Italy. Of the collected species, only Trissolcus kozlovi (Scelionidae) could develop on fresh eggs of the invasive pest Halyomorpha halys (Pentatomidae) in laboratory no‐choice tests. The results of this study have important implications for H. halys biological control.
Unintentional introduction of natural enemies has increased in recent years due to a massive rise in global trade and tourism. One such natural enemy is the Asian egg parasitoid
Trissolcus japonicus
..., a promising agent for classical biological control of
Halyomorpha halys.
In Europe, adventive
T. japonicus
populations have been detected in Switzerland, Italy and Germany. Host specificity testing demonstrated that its fundamental host range is fairly broad; however, it is unclear whether spatial or temporal refuges reduce parasitism of non-target species in the field. To address this, the realized host range of
T. japonicus
was assessed over three years by exposing sentinel egg masses of
H. halys
and 18 non-target species and collecting naturally laid egg masses in Switzerland and Italy. In total, 15 of 18 non-target species were successfully parasitized by
T. japonicus
in the field, confirming its broad fundamental host range. However, most non-target species were less parasitized by
T. japonicus
than
H. halys
, profiting from either partial temporal or spatial refuges from parasitism. Species with an unusual life cycle and the same ecological niche as
H. halys
, such as
Pentatoma rufipes
, which was the most parasitized non-target species in both countries, potentially face an increased risk of parasitism. In contrast, beneficial non-target effects may occur for the invasive pest,
Nezara viridula
, which suffered high non-reproductive mortality induced by
T. japonicus
. In both cases, life table studies will be needed to determine the impact of non-target parasitism and the potential consequences at the population level.
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.
The brown marmorated stink bug
Halyomorpha halys
is a polyphagous insect, which has a devastating impact on agricultural production in many countries. The alteration of symbiont vertical ...transmission, by removing symbionts from stink bug eggs (symbiotic control), has been recently introduced in control programmes against this insect. A major advantage of this strategy is the compatibility with natural enemies, since it allows an insecticide-free approach that is not harmful to other agroecosystem components. However, the effect of anti-symbiont products on parasitism by egg parasitoids is still unexplored. Here, we investigated the impact on parasitism by native (
Anastatus bifasciatus
,
Ooencyrtus telenomicida
and
Trissolcus kozlovi
) and exotic (
Trissolcus japonicus
and
Trissolcus mitsukurii
) parasitoids that attack
H. halys
eggs, after treatment with the micronutrient biocomplex Dentamet
®
, used for symbiotic control. The native wasp species were tested in no-choice bioassays, showing that treatment of the egg masses did not affect emergence percentages, but the non-reproductive effects were often reduced by the biocomplex. The exotic species
T. japonicus
and
T. mitsukurii
were used in no-choice and paired choice bioassays, showing an opposite influence of Dentamet
®
on emergence percentage and preference in the two species. No-choice tests indicated the highest successful parasitoid emergence on biocomplex-treated egg masses for
T. japonicus
, while no preference in the paired comparison with eggs treated with water or untreated. In contrast,
T. mitsukurii
displayed the lowest parasitism after Dentamet
®
treatment in no-choice tests, and preferred egg masses without Dentamet
®
in paired choice tests. We did not record any natural symbiont acquisition by the parasitoids emerged from
H. halys
egg masses, indicating that the wasp fitness is very unlikely to be altered by dysbiotic effects resulting from treatments. Therefore, our results support a further implementation of symbiotic control in different crops in combination with biological control, as sustainable options for
H. halys
integrated pest management.
Halyomorpha halys is a global invasive species, native to Southeast Asia, that is threatening agriculture in invaded regions. Our objectives were to: 1) establish the attractiveness of semiochemical ...stimuli paired with field-deployed traps in Europe (Greece, Hungary, Italy, and Switzerland), compared with Maryland, USA, and 2) identify H. halys haplotypes recovered from traps at each location. We found qualitatively identical patterns of capture between sites located across Europe and in Maryland, USA. In both regions, captures of H. halys adults indicated a synergistic response to traps baited with the two component H. halys aggregation pheromone, and pheromone synergist, methyl (2E, 4E, 6Z)-decatrienoate when compared with either individually. Haplotype diversity in Europe based on trapped specimens was much greater than the USA, with five new haplotypes described here, probably indicating ongoing invasion and re-introduction of H. halys. By contrast, a single, previously identified haplotype was trapped in Maryland, USA, representing a single introduction. All H. halys haplotypes responded to each semiochemical in apparent proportion to their frequency in the overall population based on independently derived information from prior work. Taken together, these data suggest that pheromone-based technology will be of global utility for the monitoring of this important invasive species.
Accurate identification of parasitoids is crucial for biological control of the invasive brown marmorated stink bug,
Halyomrpha halys
(Stål). A recent work by Talamas et al. (2017) revised the ...Palearctic fauna of
Trissolcus
Ashmead, egg-parasitoids of stink bugs, and treated numerous species as junior synonyms of
T. semistriatus
(Nees von Esenbeck). In the present paper, we provide a detailed taxonomic history and treatment of
T. semistriatus
and the species treated as its synonyms by Talamas et al. (2017) based on examination of primary types, molecular analyses and mating experiments.
Trissolcus semistriatus
,
T. belenus
(Walker),
T. colemani
(Crawford), and
T. manteroi
(Kieffer) are here recognized as valid and a key to species is provided. The identification tools provided here will facilitate the use of
Trissolcus
wasps as biological control agents and as the subject of ecological studies.
Accurate identification of parasitoids is crucial for biological control of the invasive brown marmorated stink bug, Halyomrpha halys (Stål). A recent work by Talamas et al. (2017) revised the ...Palearctic fauna of Trissolcus Ashmead, egg-parasitoids of stink bugs, and treated numerous species as junior synonyms of T. semistriatus (Nees von Esenbeck). In the present paper, we provide a detailed taxonomic history and treatment of T. semistriatus and the species treated as its synonyms by Talamas et al. (2017) based on examination of primary types, molecular analyses and mating experiments. Trissolcus semistriatus, T. belenus (Walker), T. colemani (Crawford), and T. manteroi (Kieffer) are here recognized as valid and a key to species is provided. The identification tools provided here will facilitate the use of Trissolcus wasps as biological control agents and as the subject of ecological studies.
The brown marmorated stink bug
is an invasive agricultural pest with a worldwide distribution. Classical biological control has been identified as the most promising method to reduce the populations ...of
. Adventive populations of two candidates for releases,
and
, have recently been detected in Europe. To assess their distribution and abundance, a large-scale survey was performed. From May to September 2019, a wide area covering northern Italy and parts of Switzerland was surveyed, highlighting the expanding distribution of both
and
Within four years after their first detection in Europe, both species have rapidly spread into all types of habitats where
is present, showing a wide distribution and continuous expansion. Both exotic
showed high levels of parasitism rate towards
, while parasitization of non-target species was a rare event. The generalist
was the predominant native parasitoid of
, while the emergence of native scelionids from
eggs was rarely observed. The presence of the hyperparasitoid
was also recorded. This study provided fundamental data that supported the development of the first inoculative release program of
in Europe.
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